JP7573253B2 - Additional shielding box to reduce radiation exposure and protection load - Google Patents

Description

The present invention provides an additional shielding box that can reduce the radiation exposure and radiation protection burden primarily of medical personnel in the medical field using X-ray (hereinafter referred to as "X-ray") fluoroscopy equipment.

The use of radiation in the medical field is becoming increasingly widespread, and the total number of radiological examination/diagnostic devices and sequential angiography devices in Japan already exceeded 17,000 units as of 2017.
Nowadays, X-ray fluoroscopy devices are used by specialists in various medical fields (hereafter referred to as "surgeons") who perform many surgeries as clinical procedures. The use of radiation in medical treatments has steadily increased, and procedures involving radiation exposure of patients and medical staff are frequently performed. Recently, technologies such as pulsed fluoroscopy and selective angiography have further advanced, but the increased use of these devices has tended to increase the duration of exposure to X-ray radiation, resulting in an increase in medical exposure for patients and occupational exposure for medical staff. In addition, in some cases, radiation protection measures have lagged behind, which has increased the risk of radiation damage for medical staff and patients.

In recent medical fields, the use of interventional radiology (hereinafter referred to as "IVR") techniques, in which thin tubes or needles called catheters are inserted into the body while viewing X-ray fluoroscopy images or angiograms, to treat illnesses without surgery and with as little trauma as possible, is increasing year by year.
Angiography using an X-ray fluoroscopy device (hereafter referred to as "angiography device") is a method of observing the shape of the blood vessels themselves by injecting a contrast agent into the blood vessels and photographing the flow with X-rays. By injecting a contrast agent that is difficult for X-rays to pass through into the target blood vessels and then taking an X-ray, the shape of the blood vessels in the area where the contrast agent has entered can be clearly imaged.

Here, the structure, usage, and spatial dose rate of an angiography device are explained as a representative example. The typical structure of an angiography device is to install an X-ray tube either above or below the bed (hereinafter referred to as the "table") on which the patient lies, and receive the X-rays that pass through the patient with an X-ray receiver installed in the opposite direction. In an angiography device, the direct X-rays leave the X-ray tube in the X-ray source, pass through the patient, and reach the receiver, which is a straight and unidirectional irradiation path. A part of the X-rays that are irradiated from the X-ray tube and pass through the patient enters the receiver and are transmitted as fluoroscopic image data and displayed on the liquid crystal TV screen, but most of the X-rays are scattered by the patient's body and emitted as scattered rays around the device. One of the major purposes of an angiography device is to perform catheter procedures on internal organs such as the brain and heart, and blood vessels. Therefore, an angiography device is always performing fluoroscopy or observation during surgery. Since medical staff, including surgeons, spend a lot of time near the angiography system, they are exposed to a large amount of X-rays scattered by the patient's body. In some cases, surgeons perform procedures close to the system for up to 10 hours. Since surgeons frequently perform procedures on patients near the system, surgery using the angiography system can last for a long time, radiation protection for medical staff, including surgeons, is an important issue.
As described above, in medical X-ray applications, the body tissue of a patient or examinee (hereinafter referred to as the "patient's body") is the main scatterer of the irradiated X-rays.

For radiation protection of medical staff and patients, Non-Patent Document 1 (ICRP, 2017) proposes the use of "personal protective equipment" such as lead aprons, eye protection, and thyroid protection, as well as "protective curtains" such as ceiling-suspended shields (mobile ceiling-suspended screens, other hanging lead flaps, etc.) and on-board shields. However, these radiation protection equipment are intended to protect against X-rays that are scattered in a plane in a specific direction, that is, X-rays only from the intended direction. X-rays from the incident X-ray source (hereinafter referred to as "primary X-rays") are scattered by the table or the patient's body tissue, and the scattered X-rays (hereinafter referred to as "scattered X-rays") are irradiated from all directions, that is, X-rays from unintended directions are irradiated, and medical staff cannot be sufficiently protected from radiation. The effect of reducing exposure by these radiation protection equipment is limited to a specific direction. In other words, these radiation protection devices are intended to reduce the radiation exposure of medical workers to some extent, but are not a fundamental solution to reducing exposure to scattered X-rays.

Generally, medical X-ray fluoroscopy devices are often used with an X-ray tube voltage of 50 to 150 kilovolts (kV), but the corresponding X-ray energy is in the range of 50 to 150 kiloelectronvolts (KeV). Aluminum (Al) is not in the range where the photoelectric effect is the main interaction (hereinafter referred to as the "photoelectric region") at approximately 50 KeV or higher, but is in the range where Compton scattering is the main interaction (hereinafter referred to as the "scattering region"). In other words, Al does not absorb much X-rays, but scatters them. In addition, elements with smaller atomic numbers than Al, such as carbon (C)-hydrogen (H)-oxygen (O) that make up human tissue, are also in the scattering region and hardly absorb X-rays. Therefore, when primary X-rays are irradiated and interact with materials of these light elements, the majority are not absorbed but are scattered, resulting in scattered X-rays. The background techniques are explained in detail in Patent Document 1.

In an X-ray fluoroscopy device, an X-ray tube is placed either above or below the bed (hereafter referred to as the "table") on which the patient lies, and an X-ray receiver placed on the opposite side receives the X-rays that pass through the patient. Traditionally, materials such as carbon fiber reinforced plastic (hereafter referred to as "CFRP") have been used to make tables in order to avoid absorbing X-rays. In addition, pure aluminum and aluminum alloys (hereafter referred to as "Al-based") have been used as metals. In other words, all conventional tables are made of materials consisting of light elements that absorb little primary X-rays. Therefore, although they absorb little primary X-rays, they generate scattered X-rays due to scattering.

It is also known that the primary X-rays from the X-ray source are scattered by the patient's tissues, which are mainly composed of light elements such as C-H-O, and many more scattered X-rays are generated. The scattered X-rays generated by the patient's body are scattered in all directions, including forward, side, and backward, because the patient's body is thicker than the table, and the number of X-rays that are re-scattered stochastically increases. In an under-tube type X-ray source located below the table, the backward scattered X-rays generated by the patient's body are irradiated onto the table surface located below the patient's body. In the case of the under-tube type, the scattered X-rays toward the rear (toward the floor surface) have the largest number of photons, and this is said to be about half of the scattered X-rays generated.
The material of the conventional table mentioned in the previous section scatters these rays without absorbing them, so they are re-scattered from the table, generating scattered X-rays. Even in the case of scattered X-rays that are scattered backwards from the patient's body, this re-scattering can change direction and cause them to become scattered X-rays to the side or front.

In medical X-ray fluoroscopy devices, primary X-rays generated by an X-ray source pass through a CFRP table and hit the body tissue of a patient or examinee, where most of the X-rays are scattered, some are absorbed, and the remaining several percent are transmitted. According to Patent Document 1, for example, in the case of an under-tube type primary X-ray of about 100 KeV, approximately 80% is scattered by the body tissue and the table, several tens of percent is absorbed, and approximately 5% is transmitted. It is stated that when the primary X-ray is about 40 KeV or more, absorption by the photoelectric effect (photoelectric absorption) is not dominant between the body tissue and the table, and Compton scattering is the dominant interaction.
For ease of understanding, Patent Document 1 gives the following example. That is, when the primary X-ray is "100", the transmission rate to the X-ray receiver is "3". Similarly, the absorption by the body tissue (chest) is "14", and the absorption by the CFRP table is "3". That is, when the primary X-ray is 100, the absorption by the human body and the transmission rate are considered to be 20 in total, and the remaining 80 is considered to be the scattered rate. Furthermore, the 80 of the scattered rate is generally considered to be "44" at a height of 50 cm, "24" at a height of 100 cm, and "12" at a height of 150 cm.
That is, in the case of the under-tube type, the number of scattered X-ray photons is about 12% above the patient, about 24% to the side, and about 44% below. Previous reports have provided some information on the number of scattered X-ray photons in the front, side, and back, but there is not much information on the X-ray energy. The balance of X-rays is explained in detail in Patent Document 1 by the same inventor. However, in Patent Document 1, the X-ray ratios described there should be understood only as a rough image and should not be discussed as strict numerical values.

In the under-tube type, the number of photons of the scattered X-rays scattered upward, i.e., forward, by the patient's body is expected to be roughly 12%, as described above. According to the definition of Compton scattering explained in Table 3 of Patent Document 1, the energy of the forward scattered X-rays scattered only once is 97 KeV at a scattering angle of 30 degrees when the primary X-ray is 100 KeV, for example.
Among the scattered X-rays scattered forward in the irradiation field and its periphery, those scattered at small angles, for example, less than 30 degrees (hereinafter referred to as "small angle scattering") maintain almost the same energy as the primary X-rays. Among them, those scattered a small number of times by the patient's body are irradiated near the head of the surgeon with high energy. However, this is expected to be a certain percentage of the number of photons of the scattered X-rays scattered forward (forward scattered X-rays). Some of the forward scattered X-rays have become low energy due to multiple scattering. Unfortunately, at present, there are no reports of actual measurements of the energy pulse height distribution of scattered X-rays scattered forward at small angles of less than 30 degrees using an actual X-ray fluoroscopy device.

Although there are no reported examples of energy pulse height distribution in the forward direction in medical X-ray fluoroscopy devices, it is clear that, in principle, forward scattered X-rays have a higher effective energy than side or rear scattered X-rays. As mentioned in the previous section, the theoretical formula of Compton scattering shows that small-angle scattered X-rays (hereinafter referred to as "small-angle scattered X-rays") that are scattered only once and have a small scattering angle have high energy.
Thomson scattering, which targets elastic scattering of electromagnetic waves in the low energy region, can result in forward scattering (scattering in the direction of emission) and backward scattering due to interactions with patients, etc.
Although operators protect their eyes from radiation exposure with eye protection such as lead glasses, the radiation dose to the eyes is high, and there are concerns about radiation damage such as cataracts. When irradiating the area around the operator's head, in addition to the small-angle scattered X-rays due to Compton scattering mentioned above, there is a possibility that scattered X-rays due to Thomson scattering in the patient's body may also be added. The occupational exposure of IVR workers is important, but the exact exposure dose to the lens of the eye (hereinafter referred to as "lens dose") has not been clarified until now.

Recently, a survey of the actual lens dose and an evaluation of the protective effect when protective glasses are used have been conducted by non-patent literature 2 (Kouichi Senda et al., 2018) and others. In non-patent literature 2, a survey of the actual lens dose (3 mm dose equivalent) of medical personnel involved in IVR was conducted using a new lens dosimeter (DOSIRIS). The protective effect of lead glasses in IVR was evaluated. As a result, it was stated that the lens dose of cardiac IVR doctors was higher than the effective dose for the whole body, and in some cases it reached 22 millisieverts (mSv) in one year. Therefore, it was stated that IVR doctors are at high risk of exceeding the lens equivalent dose limit when not using protective glasses, and that it is expected that the lens equivalent dose limit will be exceeded even when protective glasses are used.
In addition, in a separate proposal by the authors of Non-Patent Document 2, they state that since the shielding of the bottom and sides of lead protective glasses is insufficient, improving the shielding capacity of lead protective equipment is essential, especially for protecting the crystalline lenses of IVR doctors, and that, for example, the development of lead protective glasses with bottom protection measures is important. However, as mentioned above, under-tube type small-angle scattered X-rays have high energy. Although lead protective glasses aim to improve the shielding capacity of the bottom, they have to be lightweight to reduce the physical burden for protection. Therefore, there is a certain limit to sufficiently reducing the radiation exposure dose of the crystalline lenses of the surgeon.

Furthermore, the number of photons of the scattered X-rays (side scattered X-rays) scattered to the side (horizontally) by the patient's body in the X-ray fluoroscopy device was roughly estimated to be about 24%, as described above. According to the theory of Compton scattering described in Patent Document 1, for example, when the primary X-ray has monochromatic energy of 100 KeV, the side scattered X-rays scattered only once will have a scattering angle of 60 degrees of 91 KeV, 90 degrees of 83 KeV, and 120 degrees of 77 KeV. It can be seen that the energy of the side scattering is lower after one scattering than the forward scattering described above. Since the side scattered X-rays also include those with low energy due to multiple scatterings, it is expected that the energy will be lower on average than the forward scattered X-rays, and the number of photons will be greater in the process.
If the patient's body is thick in the irradiation field and its vicinity (hereinafter referred to as "near the irradiation field"), the probability of multiple scattering increases, and the side-scattered X-rays have a range of scattering angles and energies. There are some examples of measuring the energy pulse height distribution of side-scattered X-rays that are irradiated by an actual X-ray fluoroscopy device and scattered to the side by hitting the patient's/subject's body tissue or table, but not many of them are available.
Among them, Non-Patent Document 3 (Kazuma Matsumoto et al., 1999) shows actual measurement data of the energy pulse height distribution for each energy of X-rays after side scattering and X-rays after transmission using an acrylic phantom. The side scattering radiation at a scattering angle of 90 degrees measured at a tube voltage of 110 kV without a filter has a bell-shaped shape close to a normal distribution, the median value of the peak position is about 65 KeV, and the maximum value is about 87 KeV. The minimum value is a shape in which the photon number value tails toward the lower limit of measurement in the actual measurement value, but the estimated value expressed analytically from the theoretical formula is about 35 KeV.

The scattered X-rays generated from the upper and side near the irradiation field of the patient's body have the above-mentioned tendency, but because the scattered X-rays are re-scattered inside the patient's body, they are actually generated from the entire body of the patient, including the lower part. These scattered X-rays are re-scattered several times, and their energy becomes lower than the above-mentioned scattered X-rays from the front and sides.
On the other hand, scattered X-rays that have been re-scattered propagate in the direction of the patient's body height (hereinafter referred to as the "body axis direction").Actual measurements have confirmed that scattered X-rays are generated upward, sideways, and downward in human tissues within a range of 40 cm in the body axis direction from the irradiation field. Paradoxically, no scattered X-rays are generated at positions beyond 40 cm from the irradiation field, so there is no need to shield these areas with additional shields, etc.

Non-Patent Document 1 states that in the case of the under-tube type, the number of photons measured at the position under the table is two to three times that of the primary X-rays. This phenomenon indicates that the number of photons of X-rays scattered below the table (backscattered X-rays), which corresponds to the rear of the X-ray irradiation direction, is greater than the number of photons of X-rays scattered forward and to the sides.
As mentioned above, the number of photons of the scattered X-rays (backscattered X-rays) scattered backward (downward) by the patient's body in the X-ray fluoroscopy device was roughly estimated to be about 48%. According to the theoretical formula of Compton scattering explained in Patent Document 1, for example, when the primary X-ray has monochromatic energy of 100 KeV, the backscattered X-rays scattered only once have a scattering angle of 135 degrees at about 75 KeV, 150 degrees at 73 KeV, and 180 degrees at 72 KeV. It can be seen that the energy of the backward scattering is lower after one scattering than that of the forward or side scattering. Some of the backscattered X-rays have low energy due to multiple scatterings, and it is expected that the energy will be even lower on average than that of the side scattered X-rays, and the number of photons will be greater.

As mentioned above, there are three directions of scattered X-rays: forward, side, and backward. These scattered X-rays are roughly divided into three types according to the source and their energy. The highest energy is small-angle scattered X-rays generated from the irradiation field and its surroundings upward (forward of the under-tube type), which is included in forward scattered X-rays. The next highest energy is scattered X-rays generated near the irradiation field, which is included in all-directional scattered X-rays forward, side, and backward. The weakest energy is scattered X-rays generated from the whole body of the patient within 40 cm of the irradiation field and re-scattered several times by human tissue (hereinafter referred to as "scattered X-rays from the whole body"), which is included in all-directional scattered X-rays forward, side, and backward.
The average energy of scattered X-rays is highest for forward scattered X-rays, followed by side scattered X-rays, and lowest for back scattered X-rays.

Non-Patent Document 4 (Kouichi Senda, 2008) measures and evaluates IVR operator exposure and explains radiation protection. It states that one of the main causes of operator exposure is scattered X-rays from the patient's body, and that the incidence surface of the primary X-rays on the patient's body has a large X-ray absorption, so a lot of scattered X-rays are generated from there.
"Uneven exposure" refers to the fact that the radiation dose received by the body is not uniform, and corresponds to the case where a protective apron is used. In Non-Patent Document 4, seven IVR operators were measured by wearing one personal dosimeter (fluorescent glass badge) on each of the head and neck (outside of the protective apron: Hout) and the chest and abdomen (inside of the protective apron: Hin). There are many international evaluation formulas for the effective dose of uneven exposure, but when comparing the conversion formula commonly used in Japan, effective dose = 0.11Hout + 0.89Hin, with only Hin, it is stated that the former is approximately 3.8 times larger.
Non-Patent Document 4 states that, based on these results, if a personal dosimeter evaluates using only one Hin, the effective dose may be evaluated at about one-fourth the normal value. In addition, it states that compared with ordinary medical radiation handlers, IVR operators are more likely to be exposed to uneven radiation from scattered X-rays from unintended directions, so it is important to take into consideration the measurement of radiation exposure management.

Furthermore, Non-Patent Document 4 (Kouichi Senda, 2008) measures and evaluates the effective dose when using a ceiling-mounted lead-containing acrylic protective device with a lead equivalent of 0.8 mm, which is a type of protective curtain, and a horizontal bed-type lead apron with a lead equivalent of 0.35 mm, and explains the reduction effect in terms of radiation protection. These are a type of additional shielding for radiation protection of IVR operators that can block horizontally scattered X-rays. The reduction rate of effective dose by wearing these protective curtains, etc. is 95% in ionization chamber survey meter measurements during water phantom measurements, which do not reflect the operator's movements, but it is reduced to 42-45% in measurements using the operator's personal dosimeter (Luxel badge) during actual cardiac catheterization. Non-Patent Document 4 states that, based on these results, protective curtains, etc. are useful for protecting operators from radiation, but the reduction effect on operator exposure during actual cardiac catheterization was smaller than the measurement results of the air dose during the water phantom experiment. Therefore, they state that further improvements in additional protective equipment and ergonomic improvements are necessary. This is the same as the above-mentioned point in this specification that it is important to consider exposure to scattered X-rays from unintended directions when using current radiation protection equipment.

On the other hand, in recent years, in order to reduce the scattered X-rays that scatter upward from the patient's body, a commercially available lead-containing (Pb) sheet or other drape may be placed over the patient on the table as a shielding material. This Pb sheet, which is a type of protective curtain, attenuates and absorbs some of the scattered X-rays that scatter upward from the patient's body. However, as described in Patent Document 1, it is difficult to say that Pb alone has excellent ability to absorb scattered X-rays in the medium energy range of around 50 KeV. In addition, Pb emits characteristic X-rays (L-X) of the L shell of approximately 15 KeV or less due to shielding. Furthermore, the Pb sheet cannot be placed near the irradiation field so as not to block the penetrating X-rays, and can only be placed on a limited part of the patient's body, so its effectiveness is limited. In other words, the drape is not effective against scattered X-rays from human tissue in the irradiation field, which is where they are most likely to occur. Therefore, this method is not a sufficient measure to protect medical personnel from radiation.

Patent Document 2 proposes an X-ray equipment human body protection device to be installed on the table of an X-ray fluoroscopy device. In this device, one side end of a protective cover with a concave curved back and shielding function is rotatably slid to one side of a bed, the protective cover is bridged to one side of the bed, and the pivoting position of the protective cover is movable in the longitudinal direction of the bed. In other words, Patent Document 2 is a protective cover with shielding that can slide in the body axis direction on the table and can be opened and closed by a so-called hinge, and is an additional shield to protect the human body from radiation. The shape of the protective cover is similar to that of the semi-cylindrical dome type of Patent Document 3, which is divided in half in the body axis direction. It is said that the material of the protective cover is a stack of multiple lead-containing rubber sheets.
The human body protection device of Patent Document 2 was invented in 1977, and at that time, IVR and angiography devices were not yet widespread, and it is expected that the invention of Patent Document 2 is mainly intended for an overtube type X-ray camera for X-ray transmission image capture. With this background, the function and structure are fundamentally different from the present invention, which is intended for IVR. First, both ends of the protective cover of Patent Document 2 are open and open. It seems that this device does not take into consideration the scattered X-rays from all directions that are scattered many times by the patient's body or the table. Therefore, the scattered X-rays leak from both ends into the external space such as the inside of the examination room. In addition, since the purpose is not originally to perform a procedure using IVR, no mechanism or function is considered for the operator to insert his/her arm inside the protective cover. Furthermore, no consideration is given to small-angle scattered X-rays, in which primary X-rays are scattered at small angles by the patient's body and irradiate the head or eyes while still at high energy, and no mechanism or function exists to prevent this. Furthermore, Patent Document 2 does not consider changing the surface material depending on the type or energy of the X-rays to be irradiated. Furthermore, there is no concept of using a specific material for the surface to attenuate and absorb scattered X-rays.

Patent Document 3 is an example of an additional shield for scattered X-rays, and proposes a radiation shield device for X-ray computed tomography (CT). This is a semi-cylindrical dome-shaped radiation shield that is installed to surround the body of a patient lying on a table, and has a structure that allows it to slide on the table in the body axis direction. Both ends of the semi-cylindrical dome are open, and it is assumed that one end is in close contact with the gantry of the X-ray CT device. In addition, the semi-cylindrical dome shield does not have a mechanism or function for the operator to insert his/her arm inside. It proposes a device that samples tissue from the patient from the open end at the end opposite the gantry. Therefore, this device is not intended to reduce the radiation dose rate in a space such as a medical room, but is intended to protect only the operator from scattered X-rays that are linearly irradiated from the patient's body to the operator.
The radiation shield device of Patent Document 3 is based on the premise of X-ray CT, and one end uses the hollow part and wall of the gantry, so the function and structure of the present invention, which is targeted at IVR, are fundamentally different. First, the radiation shield device of Patent Document 3 has both ends open, and scattered X-rays leak into the space inside the examination room, etc., as in Patent Document 2. In addition, since X-ray CT does not assume that the surgeon will frequently perform procedures nearby, there is no mechanism or function for the surgeon to insert his or her hand inside through the shield, as in Patent Document 2. In addition, as in the previous section, small-angle scattered X-rays are not taken into consideration, and there is no mechanism or function to prevent them. Furthermore, Patent Document 3 does not definitively describe the material of the semi-cylindrical dome-shaped shield. Since the material is not determined, there is no idea of attenuating and absorbing scattered X-rays with a specific material, and there is no idea of changing the surface material depending on the type or energy of X-rays.

Non-Patent Document 5 introduces a radiation protection cabin developed to reduce the radiation dose of the operator. It is expected that this protection cabin is intended for under-tube type angio devices. This protection cabin is a box-shaped, movable on wheels with three sides made of 2 mm thick lead glass, and a medical professional pushes the device to set it up next to the operating table. The operator puts his/her arm through the arm insertion section further below the three sides of the box and performs the procedure with the inserted hand. Non-Patent Document 5 reports that since the early days of its use, it has been found to have a radiation protection effect equal to or greater than that of protective clothing in cardiac catheter ablation (cryocoagulation) treatment and cardiac device implantation procedures, and states that it is particularly excellent in that the operator's entire body is covered.
This protective cabin is presumed to be an additional shield for the scattered X-rays in the front and sides of the patient's body, but the difference in radiation intensity and photon number of the scattered X-rays in the front and sides is not taken into consideration. The protective cabin in Non-Patent Document 5 uses three sheets of lead glass (front and both sides), so it is thought to have open ends at the top and bottom. Scattered X-rays leak into the space inside the examination room, etc., at the top and bottom, as in Patent Documents 2 and 3. In addition, although lead glass is used, there is no thought of attenuating and absorbing scattered X-rays generated in the front and sides from a wide area of the patient's body. Furthermore, if all the lead glass is used flatly with a thickness of 2 mm, it is thought that small-angle scattered X-rays with high X-ray energy will leak from the upper open end, and shielding and radiation protection for the operator's head and eyes are not taken into consideration. In addition, protection of the operator's arms, which are thought to be inserted inside from the lower open end, etc. is not taken into consideration. Furthermore, shielding and radiation protection for the operator's lower abdomen from the upper open end is not taken into consideration. Furthermore, the shielding area is limited to only the area of one surgeon, so this device cannot reduce the air dose rate in the examination room, etc. Similarly, since it cannot receive support from other medical staff, it can only be used when the surgeon is performing the procedure alone. Therefore, the protective effect of the radiation protection cabin is limited.

As shown in Non-Patent Document 1, the phenomenon in which the number of photons measured at the position under the table is two to three times that of the primary X-rays clearly indicates that many of the primary X-rays are already being scattered and spread into the external space of the examination room without being absorbed, and are causing exposure of patients, operators, and medical staff as scattered X-rays.
The reason why the spatial dose rate is high over a wide area within examination rooms, etc. is that sources of X-rays other than the X-ray tube, i.e. sources of scattered X-rays such as the patient's body and the table (hereinafter referred to as "scatterers"), are not adequately shielded and these scattered X-rays are left unattended without being absorbed and eliminated.
Due to this situation, in the modern medical field, because X-rays irradiated to patients or examinees scatter and fly around, it is stipulated that the entire X-ray treatment room or radiography room must be shielded as an X-ray examination room. In addition, medical staff such as surgeons are forced to perform medical procedures in examination rooms where scattered X-rays fly in all directions, and they currently perform operations and examinations while wearing personal protective equipment such as heavy protective clothing shielded with lead or lead-free alternative elements.
In other words, these radiation protection devices are designed based on the assumption that scattered X-rays will be flying around, but they protect medical personnel from being exposed to X-rays from all kinds of unintended directions by blocking X-rays from intended directions.
This violates the shielding design principle, which states that "shielding should be placed as close as possible to the radiation source," and the radiation protection principle, which states that "radiation exposure should be justified and as low as reasonably achievable," and should be reviewed as soon as possible.

What has been devised and used at present are the above-mentioned personal protective equipment, radiation protection equipment such as protective curtains, protective covers for human body protection equipment, and additional shields such as radiation shielding devices. Most of the radiation protection equipment and additional shields are aimed at reducing the radiation dose of medical staff such as surgeons by directly shielding X-rays from the intended direction of the patient's body and table with a shielding material such as lead. These do not take into consideration the reduction of radiation dose of medical staff such as surgeons and patients due to scattered X-rays that spread throughout the entire space such as a treatment room and are irradiated from various unintended directions. In addition, they do not consider reducing the air dose rate in a treatment room. In other words, they do not aim to reduce the air dose rate by attenuating and absorbing scattered X-rays by changing the surface material according to the type or energy of the irradiated X-rays.
In addition, all protective curtains, additional shields, etc. do not take into consideration the small-angle scattered X-rays from under-tube type X-ray fluoroscopy devices, and do not have any mechanism or function to prevent exposure of the operator's head and eyes to high-energy small-angle scattered X-rays.
Furthermore, protective curtains, additional shields, etc. other than the radiation protection cabin do not take into consideration procedures such as cardiac catheterization using an IVR angiography device, and no mechanism or function is considered that would allow the surgeon to insert his or her arm inside through the shield.
Furthermore, conventional protective curtains, additional shields, etc. do not significantly reduce the spatial dose rate within examination rooms, etc., making it difficult to reduce the radiation exposure dose and the burden of radiation protection for surgeons and other medical staff and patients.

In Patent Document 1, which has the same inventor, a composite absorbing material is devised that effectively attenuates and absorbs scattered X-rays from a scatterer (patient body or table). The composite absorbing material is mainly composed of a low-reflection attenuation layer (first layer) of lead (Pb) and a multilayer absorbing layer (diffuse absorber, electronic absorber). By arranging one to three pairs of diffuse absorbers and electronic absorbers overlapping each other without any gaps, the incident scattered X-rays are attenuated as efficiently as possible and then absorbed in linear energy. X-rays are extinguished by converting their energy into kinetic energy such as photoelectrons. This makes it possible to reduce the radiation dose rate in a space such as a medical room, and to reduce exposure to patients and medical staff to a necessary and minimum level. In other words, the composite absorbing material attenuates and absorbs scattered X-rays from a scatterer by a material that is made up of three or more layers with different roles that are closely packed together in a multilayer structure. The composite absorbing material is one of the main materials that constitute the structure of the present invention. The composite absorbing material of Patent Document 1 is used in various parts of the additional shielding box of the present invention, which proposes a new structure and method. Details of the composite absorbent material in Patent Document 1 will be described later in Example 5.

In Patent Document 4, written by the same inventor, a medical table that transmits X-rays well and eliminates scattering is devised. A medical table should support the weight of a patient, transmit primary X-rays to the irradiation field, generate as little scattered radiation as possible, attenuate and absorb scattered X-rays from scatterers, and be capable of adjusting the position of the irradiation field and the opening dimensions (area).
Patent Document 4 discloses a medical table that is made up of a part or all of three levels, a top plate, an intermediate plate, and a bottom plate, the surfaces of which are made of a low reflection material or a composite absorption material.
That is, the primary X-rays that pass through the hollow free space (notches) of the bottom plate and the middle step pass through the mesh part of the top plate step, which is made of a material that hardly absorbs X-rays, so there is almost no interaction with materials and they are not reflected or scattered. The generation of scattered X-rays caused by the primary X-rays and their scattered rays is reduced mainly by low-reflection materials other than the irradiation field of the bottom plate step and its surroundings. In the top plate step and the middle step other than the mesh part, the scattered X-rays from the patient's body are attenuated and absorbed by composite absorbing materials. The position of the irradiation field is adjusted mainly in the middle plate and bottom plate step, and the opening dimensions (area) are adjusted to the minimum necessary to reduce the scattered X-rays generated near the irradiation field.
As mechanisms for adjusting the position of the radiation field and the aperture size, which are changed for each surgical purpose, there are mesh transmission plates that can be fitted into the top plate steps, opening and closing plates on the bottom plate steps, and aperture plates on the slide table on the middle steps, etc. The surfaces of the components are covered with low-reflection materials or composite absorbing materials, but the entire components may be made of these materials.
The table of Patent Document 4 transmits the primary X-rays to the irradiation field without interacting with the material, and limits the irradiation field to the minimum necessary opening size (area) to suppress further generation of scattered X-rays. By attenuating and absorbing the scattered X-rays generated by the patient's body placed on it, the image quality of the X-ray receiver is cleared, and the radiation dose rate in the space such as the examination room, the exposure dose of medical staff, and the burden of radiation protection can be reduced.

ICRP Recommendations Translation Review Committee (ed.), ICRP Pub. 117, "Radiation protection in fluoroscopically guided procedures performed outside diagnostic imaging departments," Japan Radioisotope Association, March 31, 2017 Tohoku University (Principal Investigator: Koichi Senda), "Research for the Incorporation and Operation of the Equivalent Dose Limit of the Lens into Domestic Regulations" report and overhead project materials, Nuclear Regulation Authority, FY2017 Strategic Promotion Project for Radiation Safety Regulation Research, 2018 Kazuma Matsumoto et al., "364. Effect of X-ray Compensation Filters on Side Scatter Spectra," Abstracts of the 55th Annual Meeting of the Japanese Society of Radiation Technology, (1999) Koichi Senda, "Measurement, Evaluation and Protection of IVR Operator Radiation Exposure," Journal of the Japanese Society of Radiation Technology, Vol. 64, No. 8, pp. 1009-1014 (2008) Japan Circulation Society et al., "Guidelines for Radiation Exposure in Cardiovascular Care (Revised Edition, 2021)", "Radiation Protection Cabin", Section 6.6.3 and Figure 27 (p. 56), (2021) Hubbell, J.H. and Seltzer, S.M., “Tables of X-Ray Mass Attenuation Coefficients and Mass Energy-Absorption Coefficients 1 keV to 20 MeV for Elements Z=1 to 92 and 48 Additional Substances of Dosimetric Interest”, NSTIR 5632, (1995) (hereinafter referred to as the “NIST Database”)

Patent Application No. 2022-161788 (domestic priority application, earlier application was Patent Application No. 2022-001336) Japanese Patent Application Publication No. 52-069595 JP 2010-279622 A Patent Application No. 2022-123002 (domestic priority application, earlier application is Patent Application No. 2022-018334) JP 2012-108103 A JP 2001-124892 A JP 2002-301052 A

The main problem that the additional shielding box (hereinafter referred to as the "box") of the present invention aims to solve is to reduce the radiation exposure dose and radiation protection burden of medical personnel such as surgeons in medical X-ray fluoroscopy devices.

The problem behind this is to block direct scattered X-rays from the scatterers and, in addition, to reduce the overall air dose rate in the examination room, etc. In other words, it is necessary to block scattered X-rays caused by primary X-rays irradiated to the irradiation field from being directly irradiated to medical personnel such as surgeons, and to reduce the overall air dose rate in the examination room, etc., without allowing scattered X-rays to leak into the air even when the surgeon performs a procedure.
Scattered X-rays are broadly classified into three directions: forward, side, and backward. In descending order of energy, there are three sub-categories: small-angle scattered X-rays from the irradiation field (forward only), scattered X-rays from the irradiation field (all directions), and scattered X-rays from the entire patient's body (all directions).

From the perspective of radiation protection for medical personnel according to the direction and classification of scattered X-rays, the first issue is to protect the surgeon's head and eyes from exposure to small-angle scattered X-rays, etc., which have high radiation energy and are projected forward from the irradiation field. The second issue is to protect the surgeon's upper limbs and trunk from exposure to the same or medium-level scattered X-rays projecting laterally from the irradiation field.

In general, in medical X-ray fluoroscopy equipment, scattered X-rays generated by the patient's body are not attenuated or absorbed, but are emitted directly into the space within the examination room, etc. This increases the air dose rate due to scattered X-rays within the examination room, etc., which exposes medical staff such as surgeons to occupational radiation and increases their radiation exposure.
In addition, ideally, X-rays should be shielded or absorbed by mechanical devices located near the X-ray source or the source of scattered radiation, but currently, surgeons and other medical personnel are protected from radiation by personal protective equipment and radiation protection equipment such as protective curtains. These cannot protect against X-rays from unintended directions. Moreover, these are heavy (hot) and uncomfortable, which increases the burden of radiation protection for surgeons and other medical personnel.
Furthermore, conventional protective curtains such as lead-containing sheets, ceiling-hanging lead-containing acrylic, and bed-side lead curtains, as well as conventional protective covers for human body protection devices and additional shields such as radiation shield devices, only block X-rays that travel directly from the patient's body toward the surgeon (intended direction). They cannot block scattered X-rays that are scattered in various directions in the examination room, and therefore cannot adequately protect medical personnel from radiation.
On the other hand, no consideration is given to protecting the operator's head and eyes from high-energy small-angle scattered X-rays from the patient's body, and no mechanism or function exists to prevent this.

The common problems with conventional protective curtains and radiation protection equipment such as additional shields are: 1) they are unable to block small-angle scattered X-rays generated in the radiation field, 2) they are unable to block scattered X-rays generated near the radiation field, 3) they are unable to block scattered X-rays from the whole body, and 4) scattered X-rays leak into spaces such as examination rooms. In addition, a common problem with conventional personal protective equipment is 5) they are unable to attenuate and absorb scattered X-rays.
Among the additional shields, the problem with the conventional protective covers and radiation shielding devices for human body protection equipment is that 6) they do not take into consideration the mechanism or function that allows the surgeon to operate inside.The problem with the conventional protective cabin among the additional shields is that although the mechanism and function that allows the surgeon to insert his/her hand inside are considered, 7) they do not take into consideration the shielding of the surgeon's arms and fingertips.

In this invention, an under-tube type box will be used as an example. The basic requirements for additional shields, etc. in an angiography device performing IVR are: a) the operator must be able to visually confirm the affected area inside the box, b) primary X-rays must be able to penetrate the affected area, and c) an irradiation field must be able to be set on the affected area. The box of the present invention responds to new findings regarding X-ray interactions and improves on the issues with previous additional shields, etc., while at least fully following the basic requirements for additional shields, etc., mentioned above.

In order to solve the problems of the conventional art, the present invention devised an additional shielding box (box) that satisfies the following seven basic requirements.
The first requirement is to block small-angle scattered X-rays with high intensity generated in the irradiation field.
The second requirement is to block moderate scattered X-rays in all directions that are generated near the radiation field.
Requirement 3 is to prevent scattered X-rays from within the box from leaking into the space within the examination room or the like.
Requirement 4 is to attenuate and absorb the scattered X-rays within the box.
Requirement 5 is to provide a mechanism that allows the surgeon to operate inside the box.
Requirement 6 is to shield the arms and fingertips of the operator inside the box.

The box structure of the present invention is composed of a box body, an end box, a top plate, a device for visually checking the inside from close range or remotely and a device for operating the inside, a hanging cloth, a sheet, a connecting device, and a supporting device. First, the structure of an additional shielding box (hereinafter collectively referred to as "box") equipped with a sight glass which is a device for visually checking the inside from close range, a sleeve port which is a device for operating the inside from close range, and a sleeve structure and the names of each component will be described.
The basic requirements for a general additional shield are that the shielding material capable of blocking scattered X-rays is installed to surround the radiation field in three dimensions, and that there is a transparent observation window that allows for visual confirmation. It is even better if there is a sleeve structure into which the medical staff can insert their arm, and if the structure allows movement in the direction of the body axis on the table. The shape of the additional shield can be a semicircular dome type or a box type, but in this invention, a box type is adopted for the reasons described below.
The box body of the present invention is a thin metal box or the like that is placed on the top surface of a table, and the head side of the shorter end face perpendicular to the body axis is the joint surface with the end face box. The longer end face in the body axis direction has an observation window at the top and a sleeve port at the bottom. A lead-containing arm sleeve is installed in the sleeve port. The shorter end face perpendicular to the body axis has a small diameter port for the lead-containing arm sleeve at the top, and a patient port (tunnel-shaped opening) and a drape holder for attaching a drape or the like at the bottom. A top plate that blocks small-angle scattered X-rays is installed on the ceiling.
The end box of the present invention is also a thin metal or, in some cases, resin box, and like the box body, has an observation window and a sleeve port on the longer end, and a sleeve port, patient port, and drape holder on the shorter end. An end top plate that blocks small-angle scattered X-rays is installed on the ceiling.
If the base material of the box body or end box (hereafter referred to as "box, etc.") is metal, a thin metal plate such as Ti or Al is used, and various shielding materials or composite absorbing materials are used to cover the direction of the radiation source (inside in the case of an under-tube type). The thickness of the shielding material varies depending on the location. Boxes, etc. may also be made of materials other than metal.

The box is a rectangular box type with flat parts on the sides to attach the observation window, arm sleeve, and drape holder. The above-mentioned boxes are assembled on-site using a connecting device, the details of which will be described later, and have supporting devices such as suspension beams and support racks.
The top plate is a flat plate made of a single metal of an element with an atomic number of 82 or higher, and is installed separately in the box body and the end box. The shielding material of the top plate varies in material and thickness depending on the part. It is also possible to install metals of multiple elements by dividing them by length and thickness.
The observation window is a flat plate of lead-containing glass or lead-containing resin that can be seen through, and is mainly installed on the long end surface of the box or the like in the body axis direction at a specific inclination angle. If necessary for the purpose of surgery, it may be installed on the short end surface perpendicular to the body axis.
The lead-containing arm sleeve, which is one type of sleeve structure, is a hollow cylinder made of lead-containing rubber or lead-containing film, and is attached to the sleeve port of a box or the like. In many cases, the large diameter port is installed on the longer end surface in the axial direction of the box or the like, and the small diameter port is installed on the shorter end surface perpendicular to the axial direction. It is also possible to attach it directly to the observation window.
The drapes are flexible lead-containing films or lead-containing sheets made of composite absorbent materials (described later), and are placed over the patient's body at the openings below the box body and end faces. Lead-containing rubber or films or rubber containing Pb substitutes may also be used.

Next, an outline of the configuration and functions of the box of the present invention will be described.
The material constituting the box of the present invention shields (linear attenuation) various types of scattered X-rays generated in the patient's body, which scatters approximately 80% of the incident primary X-rays, while also effectively attenuating and absorbing these rays (linear energy absorption) using composite absorbing materials and other materials in various locations.
The box of the present invention is composed of a box body, an end box, a sight window, a top plate, a sleeve, a drape, a sheet, a connecting device, and a supporting device. The inner surfaces of these are covered with materials capable of linearly attenuating X-rays of various energies. The inner surfaces of the box, sight window, and connecting device are covered with composite absorbing materials or additional composite absorbing materials capable of absorbing linear energy.
Strong small-angle scattered X-rays reaching the head and eyes of the surgeon are attenuated by the tabletop. Various side scattered X-rays reaching the upper limbs and trunk are attenuated by the box, observation window, and the drape surrounding the patient's body. The arms and fingers are attenuated by the lead-containing arm sleeve attached to the box body and the lead-containing gloves worn by the medical staff. In addition, scattered X-rays generated in various places are attenuated by flexible or rigid composite absorbing materials and absorbed in linear energy. The absorbed X-rays are converted into kinetic energy of electrons in the composite absorbing material and annihilated. This reduces the radiation dose rate in the space such as the examination room, especially the radiation dose rate at the position where the surgeon stands. In addition, the surgeon and other medical staff are protected without wearing other heavy (hot) protective equipment, by only wearing lead-containing gloves and inserting their hands into the box body through the lead-containing arm sleeve, and can perform catheter surgery without hindrance to the procedure.

Next, taking into consideration the configuration and function of the box, the additional operational requirements are as follows: Requirement 7 is that the position of the box, etc., must be adjustable to match the position of the patient's radiation field. Requirement 8 is that in the case of an under-tube type X-ray camera, the X-ray receiver must be able to be stored inside the box, etc.
The measures for each requirement are explained below.

The measure to solve requirement 1 (shielding of strong small-angle scattered X-rays) is to arrange a linear attenuation material on the surface of the part irradiated with small-angle scattered X-rays close to the irradiation field, and to perform linear attenuation with low reflection. Here, the linear attenuation material is mainly an element with an atomic number of 82 or more. It is a material made of an element with a K-absorption edge higher than the effective energy of the small-angle scattered X-rays contained in the under-tube type forward scattered X-rays, and has a linear attenuation coefficient of 10 (1/cm) or more for the same energy range. For example, the atomic number (Z) and K-absorption edge (Kab) are Z=82 and about 88 KeV for lead (Pb), Z=83 and about 90 KeV for bismuth (Bi), Z=90 and about 109 KeV for thorium (Th), and Z=92 and about 115 KeV for uranium (U). Therefore, the energy range targeted by the linear attenuation material is 80 KeV or more.
The standard top plate is a rectangular metal plate or surface coating that blocks high-energy small-angle scattered X-rays that are scattered forward by the patient's body. There are no particular mechanical requirements other than the strength required for self-support. In order to avoid the generation of characteristic X-rays (K-X) from the K shell during the radiation attenuation process, materials are used that are made of elements with a K-absorption edge higher than the effective energy of the small-angle scattered X-rays that are generated. Elements with atomic numbers of 82 or more, such as Pb, bismuth (Bi), thorium (Th), and uranium (U), are mainly used.
The sight glass is a flat plate of transparent glass or resin that allows the inside of the box to be seen, and is made of lead-containing glass plate or lead-containing resin plate.

The measure to solve requirement 2 (shielding moderately scattered X-rays to the side, etc.) is to arrange a low reflection attenuation material on the surface of the part where scattered X-rays are irradiated to the side, etc. from the irradiation field, to linearly attenuate the X-rays with low reflection. Low reflection attenuation materials are elements with atomic numbers of 56 or more and 82 or less. In the energy range of 60 KeV or more and less than 80 KeV, they are in the photoelectric region where the photoelectric effect is the main interaction, and are materials with a linear attenuation coefficient of 10 (1/cm) or more for the same energy range. Many are made of elements with a K-absorption edge higher than the effective energy of the side scattered X-rays, but this is not the case for all. This is because when the characteristic X-rays (K-X) due to the K-absorption edge have low energy, they can be linearly attenuated by themselves or the surrounding materials.
Boxes and mother plates are manufactured from titanium (Ti) alloys or high-strength aluminum (Al) alloys, and the inner surface of the mother plate is coated with a low-reflection attenuation material made of a simple element or compound with an atomic number of 56 to 82. For example, the atomic numbers (Z) and K absorption edges (Kab) of coating materials are as follows: barium (Ba) has Z=56 and is about 37 KeV, gadolinium (Gd) has Z=64 and is about 50 KeV, and tungsten (W) has Z=74 and is about 70 KeV. Lead (Pb) is as described above.
The sight glass is made of lead-containing glass or lead-containing resin as in the previous section.

The measure to solve requirement 4 (no leakage of scattered X-rays into space) is to cover both ends of the box, etc. in the body axis direction with a drape or the like, and to cover the port parts where the hands are inserted with sleeve structures such as arm sleeves or gloves, thereby eliminating openings that communicate with the external space.
As described above, the openings of both ends of the box, etc. in the body axis direction are closed by hanging a drape or the like using the drape holder attached above the patient port on the lower half of the end face. The drape or the like is a thin film material made of flexible composite absorbent material, so it can be fitted to the shape of the patient's body and hung without gaps. In other words, the trunk drape attached to the opening of the patient port on the box body is hung so that there are no gaps around the abdomen, lower abdomen, thighs, etc. of the patient's body. The head drape attached to the opening of the patient port on the end face box is hung so that there are no gaps around the head, shoulders, upper arms, etc. of the patient's body. This makes it possible to eliminate gaps between the both ends of the box, etc. and the patient's body using the drape or the like.
During normal use, a lead-containing arm sleeve is attached to the sleeve port of a box or other device into which a hand is inserted. A short tube with an opening is attached to the sleeve port. The base of the lead-containing arm sleeve is folded back about 3 cm and fixed to the outside of the short tube with a fastening band. The tip of the lead-containing arm sleeve has an elastic sleeve structure, so the opening collapses when the hand is not inserted. The surgeon puts on lead-containing gloves and puts his arm through the lead-containing arm sleeve to perform the procedure inside the box. This eliminates the opening even when the surgeon does not insert his hand.

A measure to solve requirement 5 (attenuating and absorbing scattered X-rays) is to apply a composite absorbing material or the like to the main part of the box of the present invention.
The composite absorbing material is a material that is configured of a low reflection attenuation layer and a multilayer absorbing layer (a pair of a diffusion absorber and an electron absorber) as shown in the above-mentioned Patent Document 1.
As described above, the box, plates, and framework of the box, etc. are made of Ti alloy or high-strength Al alloy, and the inner surface is covered with a composite absorbent material, etc. The box, etc. itself may be made of a rigid composite absorbent material.
That is, the surface of the base material (Ti-based, Al-based, etc.) of a box or the like in the area irradiated with scattered X-rays is coated with a composite absorbing material. If there is already a radiation attenuation material or low reflection attenuation material coated for shielding, it can be upgraded as an additional composite absorbing material by laminating and covering a multilayer absorbing layer (1 to 3 pairs of diffusion absorber and electron absorber) between the base material. Furthermore, the Ti-based or Al-based base material of the box or the like may be used as the outermost electron absorber as part of the composite absorbing material. Composite absorbing materials and additional composite absorbing materials are collectively referred to as "composite absorbing materials, etc."

The solution to requirement 6 (mechanism for operating inside) is the mechanism for operating inside the box in close proximity, which is the sleeve port and lead-containing arm sleeve described above. The surgeon can wear lead-containing gloves and put his arm through the lead-containing arm sleeve to perform procedures inside the box.
Although it may cause some inconvenience when performing delicate procedures, it is acceptable to use a long lead-containing glove made of lead-containing rubber or the like that combines a lead-containing arm sleeve and a lead-containing glove.
If the radiation dose rate inside the box or the like is low, a gloveless port may be installed in the port instead of a lead-containing arm sleeve. A gloveless port is a circular plate made of lead-containing rubber with radially slits, like a round wiring hole cap. On the other hand, ports that are not likely to be used for inserting hands should be closed with a closing plate made of the same material as the box or the like to prevent scattered X-rays from leaking into the space.

The solution to requirement 6 (shielding of the surgeon's arms and fingertips) is to use lead-containing arm sleeves or lead-containing gloves attached to the sleeve port. Long lead-containing gloves made of lead-containing rubber or the like may be used instead of lead-containing gloves. The lead content and thickness of the lead-containing arm sleeves, lead-containing gloves, and lead-containing gloves are adjusted according to the air dose rate inside the box, etc. These should be made of a soft material that fits comfortably against the skin, making it easier for the surgeon to perform procedures.

The solution to requirement 7 (adjusting the box to the position of the radiation field) is based on the method of positioning the box, etc. Therefore, here, we will first explain the method of installing the box, etc. After preparing the diagonal X-ray source and X-ray receiver near the table in the angiography device and determining the position of the patient's body and its radiation field, the box of the present invention is assembled on-site.
In the case of the under-tube type, after the position of the X-ray receiver is determined above the affected area of the patient's body on the table, the box body and end box are prepared and installed. The box body is placed on the table, and the X-ray receiver is sandwiched between the end box via the connection device. Therefore, the installation position of the box and other parts is determined based on the position of the affected area of the patient's body, and the end box is installed in the intended position on the table by the patient's head, and the box body is installed in the intended position on the table by the patient's feet.
In order to facilitate left-right movement of boxes, etc. at the work site, rail grooves or guide rails may be provided at both ends of the table perpendicular to the body axis, and a sliding mechanism may be provided that is guided by these to easily move in the body axis direction.

The solution to requirement 8 (containing the X-ray receiver in a box) is to contain the X-ray receiver in a box by installing it via a connection device (connection flange or receiver joint).
In the case of an under-tube type angiography device, it is better to place the X-ray receiver as close as possible to the patient's body in order to improve image quality, so the X-ray receiver must be housed in a box, etc. It is better for the number of scattered X-ray photons inside the box, etc. to be small.
In the case of a conventional X-ray camera configuration among X-ray fluoroscopy devices, the opposing X-ray source and X-ray receiver are fixed and do not rotate. Although there are few sales cases in recent years, the basic configuration of the present invention will be described based on a conventional under-tube type X-ray camera.
In the conventional type, the X-ray receiver is housed inside the box body by sandwiching the receiver arm via a connection flange. The connection flange has a structure in which one side in the opening direction can be removed, and the receiver arm is inserted into the receiver port in the ceiling of the box body and then fastened with bolts or the like. Next, the gap around the receiver arm is filled with a sliding plate shield, eliminating the opening through which scattered X-rays leak. Finally, an end box is attached to the end face of the box body.
The inside of the box or the connecting flange is covered with an additional composite absorbing material including a radiation attenuating material. This allows the X-ray receiver to be stored in the box and the scattered X-rays generated inside the box or the like to be shielded, attenuated and absorbed.

The above-mentioned requirements 1 to 6 of the present invention are addressed in the following manner.
The additional shield box (box) is an additional shield that sets an irradiation field that transmits primary X-rays to the affected area, allowing the surgeon to perform the procedure while visually checking the affected area inside the box, and reduces the surgeon's exposure to radiation. It should shield strong small-angle scattered X-rays (requirement 1), shield moderate side scattered X-rays (requirement 2), prevent scattered X-rays from leaking into space (requirement 3), and attenuate and absorb scattered X-rays (requirement 4). It is also preferable that it has a mechanism for operating the inside (requirement 5) and can shield the surgeon's arms and fingertips (requirement 6). Although the invention will be effective with only some of these requirements, it is better to meet all of them.
The present invention is composed of a box (box body, end box), a sight glass, a top plate, a sleeve, a drape, a cover, a connecting device, etc.
The high small angle scattered X-rays generated in the irradiation field of the patient's body in the box and its surroundings are shielded by the radiation attenuation material on the top plate. It is preferable to cover the surface with a composite absorbing material instead of the low reflection attenuation material or attenuation material to attenuate and absorb the scattered X-rays. In addition, the above-mentioned radiation attenuation material and low reflection attenuation material may be covered with a multi-layer absorbing layer to form an additional composite absorbing material to attenuate and absorb the scattered X-rays.
The patient ports at both ends of the box are covered with a drape or the like, and the sleeve ports into which the hands are inserted are covered with arm sleeves or the like to prevent scattered X-rays from leaking into the space.
As described above, by changing the material coated on the surface of the component according to the type and intensity of the irradiated X-rays, which differ for each component of the X-ray fluoroscopy device, the radiation is efficiently attenuated and the radiation energy is absorbed. In addition, by adjusting the position of the radiation field and the aperture size, which are changed for each surgical purpose, the scattered X-rays are shielded without leaking into the space, and are attenuated, absorbed, and eliminated. The surface of the component is coated with a radiation attenuation material, a low reflection attenuation material, an attenuation material, a composite absorption material, or the like, but the entire component of the device may be made of these materials.

The following summarizes the contents of the requirements 7 and 8, which are the additional requirements for the on-site operation of the present invention. For the on-site operation of the present invention, the box must be adjustable to the position of the irradiation field (requirement 7). Also, in order to make the image quality of the X-ray receiver clear, it is necessary to bring it as close as possible to the patient's body during treatment, and therefore the X-ray receiver must be stored in the box (requirement 8).
The additional shield box (box) of the present invention is assembled on-site after the X-ray receiver is positioned. The box is installed within a range of about 40 cm from the radiation field, and the patient's head, lower limbs, upper limbs, etc. protrude in the direction of the body axis from the openings of the patient ports on both ends of the box, etc., and are covered with the above-mentioned drape, etc.
To house the X-ray receiver in the box, the box etc. is assembled on a table with the X-ray receiver sandwiched between them via a connecting device (connection flange/receiver joint).

The additional shield box of the present invention surrounds the radiation field with a combination of shielding materials of different types and thicknesses depending on the dose rate, and does not have any openings that communicate with the external space in any direction, and it blocks various scattered X-rays generated by the patient's body. A medical professional inserts his/her arm through the sleeve structure to perform medical procedures while visually checking the inside of the box through a peephole with shielding capabilities. In addition, composite absorbing materials are placed in various places to absorb the linear energy of X-rays that have been linearly attenuated.
This makes it possible to reduce the radiation dose rate in spaces such as examination rooms, and to reduce the radiation exposure dose of medical staff such as surgeons and patients. Furthermore, the amount of radiation protection equipment required can be reduced. Even better, it is possible to eliminate the need for radiation protection equipment. In other words, it is possible to significantly reduce the occupational exposure of medical staff and the burden of radiation protection. This can make a significant contribution to the use of this technology in the industrial field.

FIG. 1 is a basic configuration diagram of a standard type additional shielding box used in a state in which an X-ray source and an X-ray receiver are fixed. FIG. 2 is an explanatory diagram of a method for mounting an X-ray receiver using a standard type connection flange. Fig. 3 is an explanatory diagram of the correlation between the types of sleeve ports and the equipment and protective gear attached thereto. A shows the sleeve port and its shape, B shows the equipment and protective gear to be installed in the box, C shows the protective gear worn by medical personnel, D shows the method of installation on the sleeve port, and E shows the structure of the fastening band of the same. FIG. 4 is a perspective view of a standard type additional shielding box. FIG. 5 is a diagram showing the overall configuration of an additional shielding box with a built-in flat panel detector (FPD), in which an independent FPD and its movement mechanism are installed inside the box. FIG. 6 is a perspective view of an additional shielding box with a built-in FPD. Figure 7 shows the basic case structure of a composite absorbent material. a shows an outline of the structure, b shows an example of a composite absorbent material with two pairs for a total of five layers, c shows three pairs for a total of seven layers, and d shows one pair for a total of three layers. The term "pair" refers to the number of pairs of diffusion absorbers and electron absorbers in the multilayer absorbent layer.

An embodiment of the present invention will be described with reference to the drawings.
It should be noted that the additional shielding box and its components shown here are merely examples and are not intended to limit the present invention.

In the remainder of this specification, the following terms are used unless otherwise specified.
The primary source of radiation is an X-ray tube, and this primary X-ray beam is called "primary X-rays." When the tube voltage of the X-ray tube is 100 kV, the generated primary X-rays have continuous energy and the maximum energy is approximately 100 KeV. Although it depends on the state of the X-ray generator, the average value of the energy (hereinafter referred to as "effective energy") is often about 60-70% of the maximum energy, so here it is assumed to be constant at 65%. Furthermore, unless otherwise specified, the effective energy is indicated.
In the following description of the present specification, unless otherwise specified, an under-tube type X-ray fluoroscope in which the X-ray tube is located under the table will be described as an example.
Radiation that is scattered when primary X-rays hit a patient/subject, parts of the equipment, etc. is collectively called "scattered X-rays."
Among the scattered X-rays, X-rays that are scattered forward at a small angle while maintaining almost all of the energy of the primary X-rays (hereinafter referred to as "small-angle scattered") are called "small-angle scattered X-rays".
Furthermore, when primary X-rays are scattered by the patient's body or a table, etc., and are scattered forward at 0 to 45 degrees from the incident angle (hereinafter referred to as "forward scattering"), they are called "forward scattered X-rays", X-rays scattered to the side at 45 to 135 degrees from the incident angle (hereinafter referred to as "side scattering") are called "side scattered X-rays", and X-rays scattered backward at 135 to 180 degrees from the incident angle (hereinafter referred to as "backscattered") are called "backscattered X-rays". Small-angle scattered X-rays are a type of forward scattered X-rays and are included in the number of forward scattered X-rays.
Furthermore, radiography rooms, examination rooms, treatment rooms, X-ray examination rooms, etc. are collectively referred to as "examination rooms, etc."

In the remainder of this specification, the following terms are used for the materials:
In metallic materials, high specific strength Al alloys such as Al-Mg alloys (5000 series alloys) and Al-Mg-Si alloys (6000 series alloys) are called Al-based alloys, while high specific strength Ti alloys such as pure Ti and Ti-6Al-4V are called Ti-based alloys.
In addition, in the rest of this specification, unless otherwise specified, a part written as an element means a material containing that element, and unless otherwise specified, a material means a material of a simple metal element.
The materials used in the box of the present invention are linear attenuation materials, low reflection attenuation materials, composite absorbing materials, and additional composite absorbing materials. In this specification, linear attenuation materials and low reflection attenuation materials are collectively referred to as "shielding materials". Furthermore, composite absorbing materials and additional composite absorbing materials are collectively referred to as "composite absorbing materials, etc." An overview of these is shown below, and a comparison is shown in Table 1. A more detailed explanation will be given in Example 1 below. Furthermore, a shielding material that is a constituent material of the box of the present invention, or that is placed on the surface of a constituent material, is called a "member."
In this specification, the shielding ability of a material is shown divided into linear attenuation (reflection, scattering, and absorption) and linear energy absorption (absorption only), as described below.

The linear attenuation material is a material that attenuates small-angle scattered X-rays with high radiation intensity by coating the base material of the material constituting the device with linear attenuation elements such as Pb, Bi, Th, or U. The linear attenuation element is an element with an atomic number of 82 or more. The K absorption edge is at 80 KeV or more, and when small-angle scattered X-rays are irradiated by primary X-rays of 80 KeV or more (hereinafter referred to as "high") from an X-ray tube with a tube voltage of 80 kV or more and 150 kV or less, the element significantly attenuates the X-rays and does not generate characteristic X-rays of the K shell (K-X) at that time.
The low reflection attenuation material is a material in which a base material is coated with a low reflection attenuation element such as Ba, W, or Pb to attenuate side scattered X-rays with low reflection. The low reflection attenuation element is an element with an atomic number of 56 or more and 82 or less, which is intended for X-rays with an effective energy of 60 KeV or more and less than 80 KeV (hereinafter referred to as "medium") (maximum energy is less than 88 KeV), and which is in the region where the photoelectric effect is dominant (photoelectric region) even in this region. In addition, it is an element in which K-X does not occur in the effective energy region of side scattered X-rays.
A composite absorbing material is a material in which the first layer of Pb on which X-rays are incident serves as a low reflection attenuation layer, the second layer and subsequent layers serve as multilayer absorbing layers each consisting of one to three pairs of a diffusion absorber such as Sn or Mo and an electronic absorber such as Nb or Cu, and the material attenuates and absorbs scattered X-rays internally by stacking three or more layers with different roles in close contact with each other in a multilayer structure. The Pb in the first layer has the same role as the Pb in the linear attenuation material and low reflection attenuation material. In the present invention, a multilayer absorbing layer stacked on the linear attenuation material or low reflection attenuation material described above is called an "additional composite absorbing material" and is treated as having the same function as a composite absorbing material.
The composite absorbent material is described in more detail in Example 5, and further details are given in the same patent document 1 by the inventor.

Table 1

The basic configuration of the additional shielding box is shown as a standard type. The box body is unchanged, but the applied configuration in which the end face box is changed is an FPD built-in type. The configurations of the additional shielding box are compared in Table 2.
The standard box is intended for under-tube X-ray televisions with a fixed receiver arm.
The built-in FPD type is an under-tube type, and the FPD X-ray receiver is installed inside the box and can be moved freely during examination thanks to its five-axis movement function.

Table 2

Example 1 is the material used in the additional shielding box of the present invention.
The second embodiment describes the basic functions and the overall configuration of a standard type additional shielding box intended for an X-ray fluoroscope in which the positions of the X-ray source and the X-ray receiver are fixed.
Example 3 describes an option for blocking forward scattered X-rays, including small-angle scattered X-rays, which have a high X-ray intensity.
The fourth embodiment describes the overall configuration of an FPD-integrated additional shield box in which an FPD type X-ray receiver separate from an X-ray fluoroscope is housed inside a box or the like.
Example 5 is a reprint of the composite absorbent material of Example 1 of Patent Document 1.

(Materials used in the additional shielding box of the present invention)
In Example 1, the functions of the material used in the box of the present invention related to linear attenuation and linear energy absorption are described. Here, the elements that appear in the following parts of this specification are listed. By citing the NIST database in Non-Patent Document 5, elements that are easily reflected/scattered and absorbed by interaction with X-rays in various energy regions such as primary X-rays and scattered X-rays are extracted. The results are listed in Table 3.
The horizontal axis of Table 3 shows the element names: magnesium (Mg), Al, silicon (Si), Ti, iron (Fe), copper (Cu), niobium (Nb), molybdenum (Mo), tin (Sn), Ba, W, Pb, Bi, Th, and U. The vertical axis of Table 3 shows the values of specific energy, i.e., the values of "monochromatic" energy. The values in Table 3 show the results of a literature survey of linear attenuation coefficients (μ) and linear energy absorption coefficients (μen). The electronic absorption ratio (μen/μ), which is the ratio obtained by dividing μen by μ, is also shown. In Table 3, values smaller than 1 are shown as exponents. It should be noted that while actual primary X-rays and scattered X-rays are white, ranging from high to low energy, the vertical axis of Table 3 reports them as monochromatic for the convenience of measurement and notation. In addition, in the NIST database of Non-Patent Document 5, the monoenergetic energies of 50 KeV or more for which μ and μen of each element are commonly reported are only 60, 80, 100, and 150 KeV. In other words, μ and μen cannot be commonly compared at intermediate monoenergetic energies not included in the table.

In the phenomenon of X-rays penetrating a material, the linear attenuation coefficient μ (1/cm) is defined by I/I ₀ =Exp(-μt) as the definition formula 1 of the present invention. Here, I is the intensity on the outgoing side, I ₀ is the intensity on the incoming side (e.g., the number of photons or the dose rate), and t is the thickness of the material. A material with a large linear attenuation coefficient μ has a large ability to attenuate, i.e., shield, due to reflection, scattering, absorption, etc. In other words, it is clear that a material with a large linear attenuation coefficient μ has a large X-ray shielding ability (linear attenuation ability), but this alone does not tell whether reflection, scattering, or absorption is dominant.
On the other hand, the linear energy absorption coefficient (μen) indicates only the amount of energy that remains after being absorbed by electrons and not re-emitted as separate photons such as bremsstrahlung X-rays, i.e., the amount of energy absorbed electronically. A material with a large μen value has a high ability to absorb X-ray energy by converting it into the kinetic energy of electrons (hereinafter referred to as "electronic absorption"). In other words, a material with a large μen has a dominant electronic absorption ability.
The electronic absorption fraction (μen/μ) indicates the proportion of linear energy absorption in linear attenuation, that is, the proportion of X-rays that are electronically absorbed without generating additional photons (characteristic X-rays, Auger electrons, or braking X-rays) due to interaction with the X-ray. Elements with a large electronic absorption fraction generally have less reflection and scattering, and generate less secondary X-rays (characteristic X-rays and braking X-rays).

A large linear attenuation coefficient μ means high linear attenuation capacity (i.e. shielding capacity). A large linear energy absorption coefficient μen means high linear energy absorption capacity (i.e. electronic absorption capacity), with little reflection or scattering and high absorption due to interaction with X-rays. Elements with a large electronic absorption ratio (μen/μ) have low reflection and scattering rates, little generation of secondary X-rays (characteristic X-rays, braking X-rays), and a high electronic absorption rate.
In Table 3, Mg, Al, and Si have fairly small μ and μen at 50 KeV or more, but below 50 KeV, μ and μen become somewhat large, resulting in a large electron absorption rate. Ti has relatively small μ and μen values at 50 KeV or more.
On the other hand, for Fe, Cu, Nb, Mo, Sn, Ba, W, and Pb, μ and μen become considerably large below 80 KeV, and the electron absorption rate becomes large. Among them, Nb, Mo, Sn, Ba, W, and Pb have large μ even at 80 KeV or more, and W and Pb in particular have large μ even at 100 KeV or more.
In general, μen becomes a small value in an energy band slightly higher than the K absorption edge (Kab) of each element, and the electronic absorption ratio (μen/μ) is also small in that energy band.

Table 3

Linear attenuation elements are elements with atomic numbers of 82 or more. They have a K absorption edge of 80 KeV or more, and in many cases do not generate K-shell characteristic X-rays (K-X) even when irradiated with highly scattered small-angle X-rays of 80 KeV or more. As shown in Table 3, the linear attenuation coefficient μ at monochromatic energies of 80 KeV or more and 150 KeV or less is 10 (1/cm) or more. Examples of elements in Table 3 include Pb, Bi, Th, and U.

Low-reflecting and attenuating elements are elements with atomic numbers of 56 or more and 82 or less. As shown in Table 3, the linear attenuation coefficient μ at monochromatic energies of 60 KeV or more and 80 KeV or less is 10 (1/cm) or more. Examples in Table 3 include Pb, W, and Ba.

A composite absorbing material is a material in which the first layer of Pb on which X-rays are incident acts as a low reflection attenuation layer, the second layer and subsequent layers are multilayer absorbing layers consisting of one to three pairs of diffuse absorbers and electronic absorbers, and three or more layers with different roles are closely stacked in a multilayer structure to internally attenuate and absorb scattered X-rays. The role of the Pb in the first layer in terms of linear attenuation is the same as that of the linear attenuation material and the Pb in the low reflection attenuation material described above.
The second layer of diffuse absorbers is an element with an electron absorption ratio (μen/μ) of less than 70% at monochromatic energies of 50 or 20 KeV, etc. According to Table 3, in the case of 50 KeV, Ba, Sn, etc., and in the case of 20 KeV, Mo, Nb, etc., are applicable.
The electron absorber paired with the above-mentioned diffuse absorber is an element with μen/μ of 70% or more at the monochromatic energy at which the diffuse absorber is selected. In Table 3, Nb, Mo, Cu, Fe, etc. are applicable at 50 KeV, and Cu, Fe, Ti, etc. are applicable at 20 KeV.

Next, let us consider the thickness of the linear attenuation material and low reflection attenuation material, which are the shielding materials. As shown in the definition formula 1 above, the linear attenuation coefficient μ indicates the correlation between the intensity _I0 on the incident side and the intensity I on the exit side based on the thickness t of the material, and indicates the limit value of the spatial dose rate and the exposure dose.
These limit values are determined according to the conditions of each site, such as the output and characteristics of the X-ray source of the X-ray fluoroscopy device used at the site, the spatial dose rate in the examination room where radiation is managed at the site, and the limit and target values of each exposure dose. In addition, while conventional knowledge is about the energy of monochromatic X-rays, the X-rays at the site are white continuous energy. Since the conditions and conditions of each site cannot be generalized, the thickness is provisionally set as a 1/10th valence layer of the monochromatic energy value of the candidate material (hereinafter referred to as "1/10 valence layer"). Therefore, here, the 1/10 valence layer of the candidate material at monochromatic energy was calculated based on the linear attenuation coefficient μ.
Table 4 lists the half-value layer: _X0.5 and 1/10 value layer: _X0.1 calculated from the linear attenuation coefficient μ in Table 3. Calculations were made with _X0.5 = 0.693/μ (cm) and _X0.1 = 2.303/μ (cm). The incident energy of photons on the vertical axis was 10, 20, 30, 40, 50, 60, 80, 100, and 150 KeV in the case of monochromatic light.

Furthermore, the calculation results of the 1/10 valence layer in Table 4 are summarized. As mentioned above, elements of linear attenuation materials such as Pb, Bi, Th, and U are defined as 80 KeV or more, and are expressed as monochromatic energies of 150 KeV or less. Elements of low reflection attenuation materials such as Ba, W, and Pb are defined as monochromatic energies of 60 KeV or more and less than 80 KeV. Table 5 shows the results of extracting the 1/10 valence layer for each element in the corresponding monochromatic energy range from Table 4 for low reflection attenuation materials and linear attenuation materials.

According to Table 5, it can be seen that the 1/10 valence layer of each element of the candidate material varies for each monochromatic energy, and the more suitable energy region is further limited for each element. This is because when the monochromatic energy is an energy close to the K-absorption edge of the element, the 1/10 valence layer becomes large, and the variation becomes larger compared to the others. The combination of element and monochromatic energy shown in parentheses in Table 5 means a condition that is not very recommended for use due to the above-mentioned influence. However, the 1/10 valence layer is a guideline thickness, and it is not required to ensure the exact thickness under the actual on-site conditions where white continuous energy is irradiated. Generally speaking, the thickness guideline is as follows.
The linear attenuation material Pb is best used for scattered X-rays of 100 KeV or less, and has a thickness of 0.8 mm. For X-rays of 100 KeV or more, the only usable materials are Th and U, and their thicknesses are in the range of 0.4 to 0.8 mm.
The low reflection attenuation material Ba is best used for scattered X-rays of about 60 KeV, and its thickness is 0.8 mm. Pb can be used for X-rays of 60 to 80 KeV, but its thickness is in the range of 0.4 to 0.8 mm.
The thickness of these candidate materials should be precisely determined after obtaining information on the situation and conditions of use at each site. Better yet, a lead equivalent test conforming to the JIS T61331-1 standard should be carried out to confirm the shielding performance of the materials under the conditions of use at each site where actual white continuous energy is irradiated, before designing the additional shielding box.

Table 4

Table 5

(Basic functions and configuration of standard additional shielding box)
In the second embodiment, the basic structure of a standard type additional shielding box (hereinafter referred to as the "standard type box") will be described. Fig. 1 is a basic configuration diagram of a standard type additional shielding box in an under-tube type in which the X-ray source is placed under the table. The additional shielding box 1 is placed on the table 2.
First, a standard type box having an observation window, which is a device for visually checking the inside at close range, a sleeve port, which is a device for operating the inside at close range, and a sleeve structure will be described.
The standard type box is intended for X-ray fluoroscopy equipment that uses a fixed position X-ray source such as an X-ray camera and an X-ray receiver. The standard type additional shielding box 1 is composed of a box body 4, an end face box 5, an observation window 6, a top plate 7, a sleeve port 8 and a lead-containing arm sleeve 9, an end face top plate 14, a hanging cloth 22, etc.

(Explanation of basic functions of standard box)
The basic functions of the standard additional shielding box 1 of the present invention will now be described.
The additional shielding box 1 of the present invention is arranged to three-dimensionally surround the radiation field 15 corresponding to the patient's affected area, the components constituting the box have X-ray shielding ability, there are no openings communicating with the external space, and medical personnel can perform surgery by inserting their hands into the box through a sleeve structure such as a lead-containing arm sleeve 9 which also has shielding ability while viewing from the external space through a peep hole 6 which also has shielding ability.
In addition, the sleeve structure is made of a flexible material and is attached to a sleeve port 8 such as a box. By blocking the opening of the sleeve port 8 with the medical worker's arm and the tip and attachment part of the sleeve structure such as a lead-containing arm sleeve 9, the additional shielding box 1 can maintain shielding while performing surgery.
The patient places the head, limbs (legs), and other parts of the body other than the radiation field in the external space by penetrating the box in the direction of the body axis via the patient port 20, and the opening between the box and the human body is blocked with a flexible shielding cloth or the like 22 attached to the patient port 20, thereby reducing medical exposure to the head and limbs of the patient and allowing medical personnel to perform surgery while maintaining shielding. The patient port 20 may be blocked with a separate curtain-type or shutter-type shielding sheet instead of a shared cloth or the like 22.
Power, electrical signals, optical signals and liquids can be passed between the inside and outside of the box while maintaining the shielding and penetrating the box by a shielding connector 24 attached to the receiver port 13. The power cable introduced through the connector 24 is connected to a power outlet inside the box.
In the case of the under-tube type, forward scattered X-rays, including highly scattered small-angle X-rays toward the upper part of the patient's body, are shielded by a tabletop 7 made of a radiation attenuating material. Scattered X-rays to the sides of the patient's body are shielded by a box, etc. (box body 4 and end box 5) made of a low-reflection attenuation material and a viewing window 6 made of a shielded glass plate or resin plate. By combining these materials into a composite absorbing material, etc., the scattered X-rays can be attenuated and absorbed.
The image quality of the under-tube type X-ray receiver 10 is better when it is placed as close as possible to the radiation field of the patient's body, and the medical exposure of the patient can be reduced by reducing the output of the X-ray source. Therefore, it is preferable to store the under-tube type X-ray receiver 10 in a box. The standard type box is divided into a box body 4 and an end face box 5, and is constructed to be assembled on-site. The box body 4 is slid into the connection port of the end face top plate 14 attached to the box body 4, and the X-ray receiver arm 11 is inserted to attach the X-ray receiver 10 to the box body 4. The opening around the X-ray receiver arm 11 is closed with a receiver cover 12 with a shielding ability. Then, the end face box 5 is attached, and the X-ray receiver 10 can be stored and installed in the box.

(Explanation of boxes, etc.)
The box body 4 and the end face box 5 (hereinafter referred to as "box, etc.") of the present invention will be described. The box, etc. of the additional shield box 1 is assembled on-site after the X-ray source of the X-ray fluoroscope and the X-ray receiver 10 are positioned in the radiation field near the affected part of the patient. Therefore, the box is structured to be divided into two or more parts in the length direction. The overall length of the box itself is arbitrary within about 150 centimeters (cm), but the width is a maximum of 95 cm, or better about 70 cm, which is more than the width of the patient's body, in order to operate it from both sides within the range of hand length. The overall height of the box itself is 60 cm to 120 cm depending on the type and model of the X-ray receiver 10 and the moving mechanism 49 to be stored. The standard type box body 4 and the end face box 5 are shown in FIG. 1. These boxes, etc. are divided into two parts, and the end face box 5 is assembled after the box body 4 is attached to the X-ray receiver 10. The end face box 5 is fastened to the box body 4 by a spring-loaded fastener such as a trunk hook.
The box body 4 is provided with a viewing window 6, a top plate 7, and a sleeve port 8. A connector 24 is provided at the receiver port 13, and a cloth holder 23 is provided at the patient port 20. For example, by winding up (hanging up) a part of the cloth 22, the cloth 22 is hung to close the patient port 20.
The base material of the box, etc. is a lightweight, high-strength Ti-based or Al-based plate material for easy handling. These plate materials are formed by press bending or the like, and then processed into sheet metal to make holes for installing the glove port, the observation window, and the patient port. It is preferable to press bend as long a plate material as possible. The processed plate materials are screwed or joined together via L-shaped or square reinforcing metal fittings. The short tube of the glove port is screwed or joined. For example, the joining method is welding in the case of Ti-based materials, and friction stir (diffusion) welding (FSW), spot joining, brazing joining, etc. in the case of Al-based materials. In order to reduce the weight of the flat plate part of the base material of the box, it is preferable to join reinforcing ribs to the inner surface of the plate material (or the outer surface if difficult) and to reduce the plate thickness of the box. When fixing with screws that penetrate a material with a shielding function, it is preferable to use screws, screws, bolts, etc. made of W material.
The inside of the base material is the low reflection attenuation material of Example 1, in which a low reflection attenuation element such as Pb, W or Ba is attached to the surface of a predetermined thickness. The thickness of the low reflection attenuation material should be changed depending on the radiation dose rate of the installation site to optimize the correlation between the weight of the material and the shielding performance. Therefore, it is desirable to investigate the spatial dose rate of X-rays at various locations near the table at the site before designing the box. Also, if possible, it is even better to investigate the energy pulse height distribution of X-rays at various locations near the table at the site and find the average and maximum values. The thickness of the low reflection attenuation material required for shielding scattered X-rays is generally in the range of 0.3 to 0.8 mm as shown in Table 5. The thickness of the base material (Ti-based, Al-based) varies depending on the mechanical strength required from the shape of the member and the reinforcement state, but is generally in the range of 2 to 5 mm.

(Description of the tabletop)
In the case of an under-tube type X-ray fluoroscopy device, the top plate 7 installed on the ceiling of the box of the present invention will be described. The top plate is a radiation attenuating material arranged on the surface of the ceiling on the side of the box or the like where small-angle scattered X-rays are irradiated. In other words, the top plate blocks forward scattered X-rays directed upward from the patient's irradiation field and its surroundings. Since forward scattered X-rays include small-angle scattered X-rays, they have high X-ray energy.
Since the top plate 7 needs to have a higher shielding ability than the sides and bottom, it is necessary to use the linear attenuation material of Example 1. Here, the linear attenuation material is a material that is mainly made of elements with an atomic number of 82 or more, a K-absorption edge higher than the effective energy of small-angle scattered X-rays, and has a linear attenuation coefficient of 10 (1/cm) or more for the same energy range.
The linear attenuation elements that do not generate K-shell characteristic X-rays (K-X) even when irradiated with X-rays of 80 KeV or more are considered to be lead (Pb, density: 11.3 g/cm ³ ), bismuth (Bi, density: 9.7), thorium (Th, density: 11.7), uranium (U, density: 18.9), etc. The atomic numbers (Z) and K absorption edges (Kab) of these elements are Pb, Z=82, approximately 88 KeV, Bi, Z=83, approximately 90 KeV, Th, Z=90, approximately 109 KeV, and U, Z=92, approximately 115 KeV. These are alpha ray emitters, but because alpha rays have a short range even in air, they do not affect the air dose rate. As a second best option, W, with Z=74 and a K absorption edge of approximately 74 KeV, may be used. However, Th exceeding 900 grams (g) and U exceeding 300 g are internationally restricted substances, and their use requires notification to the national regulatory authorities.
Since the linear attenuation material made of these simple elements has a high shielding ability, the thickness of the material required for shielding the scattered X-rays is as thin as 0.4 to 1.0 mm, as shown in Table 5 of Example 1. Since the self-supporting strength may be insufficient with this thickness, the linear attenuation material may be attached to the base material (Ti-based, Al-based) of the box in the direction of incidence of X-rays. The top plate 7 may be a cut flat plate with the linear attenuation material attached thereto, the same as the base material, and the material may be attached to the ceiling of the box in the direction of incidence of X-rays. The linear attenuation material does not have any mechanical or strength requirements and only needs to be present in the position, so it may be attached by a simple joining method such as adhesive or double-sided tape. It may also be attached by a method such as screwing with corner fittings or the like.

(Explanation of the observation window made of a shielded glass plate)
As a device for visually inspecting the inside of the box from close range, the materials that can be used for the peep window 6 installed on the side of the box in the present invention include a shielded glass plate and a shielded resin plate. The peep window 6 can block a part of the scattered X-rays toward the side of the patient's body and toward the upper part of the patient's body. Here, the peep window 6 made of a shielded glass plate will be described. A shielded glass plate can contain a large amount of lead compounds, and is characterized by having a product with a large lead equivalent. On the other hand, compared to resin materials, the mechanical strength, especially the impact resistance, is slightly inferior, and the mass of the compound of the elements that make up the composition is slightly larger. The shielded glass plate is specified in JIS R3701 "Lead glass for X-ray protection" for the nominal thickness, minimum lead equivalent, transmission performance, dimensional tolerance, etc.
One of the glass materials that can be used for the observation window 6 is radiation shielding glass LX Premium manufactured by Nippon Electric Glass Co., Ltd. The radiation shielding safety glass of Patent Document 5 may also be used. In this glass, the component for shielding X-rays is Pb. If the PbO content exceeds 80%, the components other than PbO become relatively small, and there is a risk that the glass may become thermally unstable, so the content is considered to be 55 to 80%.
An example of the overall composition of the radiation-shielding glass is, in mass percentages calculated as oxides, 10-35% _SiO2 , 55-80% PbO, 0-10% _B2O3 , 0-10% _Al2O3 , 0-10% _SrO , and 0-10% _BaO . That is, the content of Pb+Ba is high, which corresponds to the low reflection attenuation material of Example 1. In addition, among the elements necessary to constitute the composite absorbing material of Example 1, Pb, Ba, Sr, Al, and Si are contained, but since it is a single layer, there is no outermost layer that serves as an electron absorbing layer.
The maximum dimensions of the LX Premium are 120 cm x 260 cm, so if a single window surface exceeds this dimension it must be divided into two panels.
The correlation between lead equivalent (mmPb) and product thickness (mm) is directly proportional. For example, the product thickness is 11 mm for 1.1 mmPb, 12-14 mm for 1.5 mmPb, and 14-16 mm for 2.0 mmPb. In the present invention, radiation shielding glass with 1.1 mmPb and 11 mm thickness is sufficient even in high radiation areas, and even thinner glass is acceptable. There is no product rank with a product thickness of 11 mm or less, but radiation shielding glass with a thickness of 5 mm or less can provide sufficient shielding in low radiation areas. This thin radiation shielding glass may be bonded to another glass to form a laminated glass. Furthermore, two radiation shielding glasses with different lead equivalents may be bonded to each other to form a laminated glass.

(Explanation of the observation window made of a resin plate with shielding)
Next, the observation window 6 made of a shielded resin plate installed on the side of the box of the present invention will be described. The shielded resin plate is a transparent acrylic resin plate to which a lead compound is chemically bonded. Generally, transparent lead-containing acrylic resin is obtained by copolymerizing lead-containing (meth)acrylate with methyl methacrylate. The shielded resin plate is characterized by its high mechanical strength per mass, but compared to glass materials, it contains a small proportion of lead compounds and has a relatively small lead equivalent. Transparent lead-containing acrylic resin plates were previously specified in JIS K6736 "Lead-containing methacrylic resin plates for X-ray and gamma-ray protection", but were abolished in 2000. Applications include the front panel of a glove box for nuclear power, and X-ray protection shield plates and protection screens for medical use.
One of the resin materials that can be used for the observation window 6 is Kyowa Glass XA manufactured by Kuraray Trading Co., Ltd., and the lead equivalent can be selected according to the application. The brands and specifications are H-8 with a lead equivalent of 0.3 mmPb or more, H-12 with 0.5 mmPb or more, H-18 with 0.8 mmPb or more, H-22 with 1.0 mmPb or more, and H-35 with 1.5 mmPb or more. As the lead equivalent increases, the total light transmittance decreases from 80% to 75%.
The maximum dimensions of Kyowa Glass XA are 183 cm x 244 cm, so if a single window surface exceeds this dimension, it must be divided into two pieces.

(Explanation of the coverings, etc.)
The following describes the drape, etc. 22 that is placed on the patient's body in the box of the present invention. The drape, etc. 22 can shield part of the scattered X-rays from the irradiation field of the patient's body 25, its surroundings, and the whole body toward the top and sides of the table. In other words, in the case of the under-tube type, it shields part of the forward scattered X-rays and the side scattered X-rays. It is effective to shield the scattered X-rays from the patient's body 25 in the immediate vicinity of the patient's body, which is the scattering source. Therefore, it is preferable that the drape, etc. 22 be placed in contact with the patient's body 25 and over as wide an area as possible. In addition, including the portion lifted by the drape holder 23 described later, the drape, etc. 22 needs to be placed with an excess in the body axis direction. However, since it is necessary to place the drape, etc. 22 away from the position near the irradiation field, the area on which the drape, etc. 22 is placed is inevitably limited. Similarly, since it cannot be placed near the irradiation field, it cannot shield the scattered X-rays from the irradiation field, which have a high radiation intensity.
The material of the blanket 22 must be flexible and pliable, and when placed on the patient's body 25, it must be lightweight to prevent blood congestion. Commercially available products include the blanket Softlight SCO-25 (lead equivalent: 0.25 mmPb) manufactured by Maeda Co., Ltd. Even better is the flexible composite absorbent material of Patent Document 1, which is a metal thin film laminate plate made by cladding and rolling thin Pb-Nb-Cu.

Furthermore, from the viewpoint of making the additional shielding box a compact facility, it is preferable that the patient penetrates the box through the patient port, so that the head, limbs, and other parts of the body other than the irradiation field, its surroundings, and the parts generating scattered X-rays are placed in the external environment. This also has the effect of reducing medical exposure of these parts of the patient. The drape, etc. 22 is placed on the patient's body 25 before assembling the box, etc. After assembling the box, etc., a part of the flexible curtain-type drape, etc. 22 with shielding ability is rolled up with a rotating roll by the drape holder 23 attached to the patient port 20, thereby closing the gap between the box and the human body, and thus preventing the scattered X-rays from leaking into the external space.
In Fig. 1, the drape etc. 22 is draped over the patient's body starting from two points. One is draped from the limb side end of the box body 4 in the body axis direction toward the trunk and one is draped toward the limbs. The other is draped from the head side end in the body axis direction toward the head and one is draped toward the chest. This ensures that the drape etc. 22 is not draped near the irradiation field. The length of the drape etc. 22 is adjusted with the drape holder 23 attached to the top of the patient port 20.
The drape holder 23 may be hung with a wide-mouthed clip instead of a rotating roll. Instead of the wide-mouthed clip, a pair of permanent magnets may be attached inside and outside the box. A rod-shaped curtain hanger may also be used. The drape 22 may be fixed by the drape holder 23 and hung from the patient's body 25.
Furthermore, the patient port 20 may be covered with an individual curtain-type or shutter-type shielding sheet rather than the shared drape or the like 22. In other words, by covering the patient port 20 with the drape or the like 22 or another curtain-type or shutter-type shielding sheet, the additional shield box can maintain shielding while performing surgery.

Although the material for the drape etc. 22 is required to be flexible and pliable, the radiation conditions for the drape etc. 22 at the portion attached to the patient port 20 are slightly different from those for the whole body described above. That is, since side scattered X-rays from the irradiation field and its surroundings are incident on the patient port 20 on the head side in particular, it may be necessary to use a low reflection attenuation material.
As the drape etc. 22 to be attached to the patient port 20, it is possible to use a commercially available product such as Maeda's Softlight SCO-50 drape (lead equivalent: 0.5 mmPb). In addition, a radiation shielding rubber sheet RSL-070 manufactured by Togawa Rubber Co., Ltd. with a thickness of 5 mm (lead equivalent: 0.66 mmPb) to 10 mm (same: 1.24 mmPb) may be used by hollowing out the penetration part of the human body.
It is also good to use a low reflection attenuation material made of a metal sheet formed by rolling a single piece of Pb, which is the low reflection attenuation element, with a thickness of 0.4 to 0.8 mm. Even better is the flexible composite absorbing material of Patent Document 1, which is a metal thin film formed by cladding and rolling Pb-Sn-Nb.

(Description of connector)
The connectors 24 installed at various locations on the ceiling and side of the box of the present invention will be described. During surgery, many instruments are connected to the patient's body, and medicinal fluids are supplied and discharged. When the additional shielding box 1 is not present, electrical and signal connections and fluid supply and drainage can be easily performed without special consideration, but when the additional shielding box 1 is installed, the method must be considered. In emergencies and short-term use, items can be carried in and out, electrical signal connections, and fluid supply and drainage can be performed through the side end opening 28 or the patient port 20. Infusions, etc. can also be installed on a hook on the ceiling of the box body. Permanent electrical and signal connections and fluid supply and drainage are performed by the connectors 24 with shielding ability attached to the receiver ports 13 on the ceiling and side ends of the box body. This allows communication through the box, and electrical and signal connections and fluid supply and drainage between the inside and outside of the box, etc. can be performed while maintaining shielding without providing an opening.
In Fig. 1, the connectors 24 are provided on the ceiling, with three rows of thin electrical/signal connectors and two rows of slightly thicker connectors for liquids. A power outlet is provided inside the box, etc. Since the observation window 6 has a large surface area, the interior is sufficiently bright with ceiling lighting in the examination room, etc., but spotlight-type local lighting fixtures, etc., are installed in various places inside the box, etc. as necessary. It is possible to increase the number of connectors 24 in the box, etc., and it is also possible to increase or decrease the number of electrical/signal and liquid connectors therein.
Commercially available airtight electrical and signal connectors that can be used for the connector 24 include hermetic connectors manufactured by Daitron Co., Ltd.
The liquid connector is placed in the hollow guide cylinder. A thin short tube is used to lead the liquid from the hollow guide cylinder into the box through a small through hole in the wall of the box. Commercially available liquid connectors include the closed connector made by Top (Sefio Flow Connector SC, medical device registration number: 21400BZZ00227000). This product is a needleless valve type three-way stopcock connector used for administering medicines, taking blood, and protecting connections. When feeding liquid, it is connected with an extension tube with a closed three-way stopcock, and a closed environment is maintained when the liquid bag is removed. The main body is made of polycarbonate, and the valve is made of silicone rubber. The inlet side and outlet side can be selected depending on the direction in which the closed connector is inserted, and it is a consumable item that is replaced after each surgery.
When aspirating and discharging the patient's body fluids and other wastewater, cleaning and disinfection are required after surgery, but an extension tube may be directly inserted into a small through hole in the wall of the box.

(How to adjust the position using a box, etc.)
The position adjustment method by assembling the box of the present invention will be described. The assembly method of the standard type box will be described with reference to Fig. 2. The position of the additional shielding box 1 must be adjusted based on the position of the radiation field of the X-ray fluoroscope, which is determined by the purpose of the surgery (the affected area of the patient). The box is divided into two or more parts in the body axis (length) direction, so that it can be assembled on-site. In the case of the standard type box, it is divided into a box main body 4 and an end box 5.
Furthermore, the resolution of the under-tube type X-ray receiver 10 is better and the patient's exposure to radiation can be reduced if the receiver is located as close as possible to the irradiation field of the patient's body 25. In order to bring the X-ray receiver 10 close to the patient's body 25, it is preferable to store the under-tube type X-ray receiver 10 in a box. Therefore, after the positions of the patient's body and the X-ray receiver 10 are determined according to the purpose of the surgery, assembly of the box and adjustment of its dimensions are started.

FIG. 2 shows the state at the point where the position of the X-ray receiver 10 has been determined and the receiver arm 11 is about to be inserted into the box body 4.
By sliding the box body 4 towards the X-ray receiver 10, the X-ray receiver arm 11 is inserted into the receiver port 13 of the end surface top plate 14. After insertion, the connection flange cover 29 is attached by pushing it into the end surface top plate 14 with an embedded bolt.
In the standard type additional shielding box 1, the X-ray receiver 10 is stored and installed inside the box in the above-mentioned manner, and surgery can be performed while maintaining shielding.

Flat panel detector (FPD) type X-ray receivers 10 have undergone remarkable technological advances through development, and in recent years have become smaller and lighter. It is believed that there are no technical problems in making the receiver arm 11 of the angiography device thinner or longer.
Furthermore, it may be possible to eliminate the image receiving arm 11 itself and store the FPD in a box, separate from the X-ray fluoroscopy device, as in the fourth embodiment. Therefore, if there is further need for the present invention in the future, the manufacture and sale of small, lightweight, independent FPDs may accelerate. Details of the development status of FPDs will be described later in the fourth embodiment.

(Sleeve port explanation)
The sleeve port 8, which is a device for operating the inside of the box by approaching it, and the sleeve structure are shown in Fig. 3. The lead-containing arm sleeve 9, lead-containing glove 54, and gloveless port 60 shown in Fig. 3 are collectively called the "sleeve structure."
One of the sleeve structures is a lead-containing arm sleeve 9, which is attached to a plurality of sleeve ports 8 of a box. In FIG. 1, the sleeve ports 8 are provided with four large diameter ports 50 on each side of the long end face of the box body, for a total of eight ports on both sides. Also, two small diameter ports 51 are provided on the short end face of the box body, and two small diameter ports 51 are provided on the end face box, for a total of four ports. The sleeve port is a hollow short tube with a diameter of 14 to 22 cm and a length of about 3 to 7 cm attached to a box or the like. The outer surface may be provided with an uneven shape that makes it easier to fasten the lead-containing arm sleeve 9 with a fastening band 52. The sleeve port is made of the same material as the base material of the box or the like. An example of the shape of the sleeve port 8 is shown in FIG. 3A. a-1 is the shape of the large diameter port 50, and a-2 is the shape of the small diameter port 51.

The opening shape of the large diameter port 50 is an ellipse that is long in the horizontal direction, and there is a margin for moving the hand sideways while keeping it inserted, making the procedure easier. The opening shape of the small diameter port 51 is a circle with a diameter of about 14 to 16 cm due to dimensional constraints on the installation position. If a field of view at hand is required, the sleeve port for the small diameter port 51 may be attached to a transparent lead-containing acrylic plate and installed in a box or the like.
In this way, since a large number of sleeve ports 8 can be installed in a box or the like, during surgery, not only the surgeon but also the assistant can insert their hands into the box at the same time. The number of medical personnel who need to insert their hands varies depending on the surgery, but the number of sleeve ports 8 can be more or less.

(Lead arm sleeve description)
The lead-containing arm sleeve 9 of the box of the present invention will be described. One of the sleeve structures is the lead-containing arm sleeve 9 without a glove portion, but a lead-containing glove 54 with a glove portion may also be used. In the case of the lead-containing arm sleeve 9, the medical staff puts on a separate lead-containing glove 56 and inserts the arm. This is because the lead-containing glove 56 is easier to perform delicate procedures with than the lead-containing glove 54 and is less expensive. The concept of these combinations will be described with reference to FIG. 3.

3 is an explanatory diagram of the relationship between the types of sleeve ports 8 and the equipment and protective gear attached thereto. A shows the sleeve port and its shape as explained in the previous section. B shows the equipment and protective gear installed in the box, and C shows the protective gear worn by medical personnel.
Explaining this side-by-side with the large diameter port 50 a-1 in Figure 3, if the lead-containing arm sleeve 53 b-1 is installed in the box, the medical staff will only wear the lead-containing glove 56 c-1. If the lead-containing glove 54 b-2 is installed in the box, the medical staff will not wear any protective equipment. However, since these gloves for the box do not provide good operability for the fingertips, it is unlikely that the surgeon would use them for the procedure, but they are useful for assistants. The above content is also the same for the small diameter port 51 a-2.
Fig. 3d shows a method of installation to the sleeve port 8, and Fig. 3e shows the structure of the fastening band. The lead arm sleeve 9 and the lead globe 54 are attached to the sleeve port 8 by the fastening band 52 as shown in Fig. 3d. The fastening band 52 can fasten the lead arm sleeve 9 and the lead globe 54 by screwing the screw 59 in the housing 58 as shown in Fig. 3e.

If the radiation dose rate inside the box or at the sleeve port 8 is low, a gloveless port may be installed in the port instead of a lead-containing arm sleeve. The gloveless port is a disk with radially slits, like a round wiring hole cap. The medical staff inserts their arm through the slits. Explaining this side-by-side with the small diameter port 51 of a-2 in Figure 3, if the gloveless port 60 of b-3 is installed in the box, the medical staff needs to wear lead-containing gloves 56 and lead-containing arm cover 55 to protect themselves from radiation exposure. On the other hand, ports that are not likely to have hands inserted should be closed with a closing plate made of the same material as the box to prevent scattered X-rays from leaking into the space.

The tip of the lead-containing arm sleeve 9 is closed by attaching a cuff rubber or the like made of a stretchable material that is elastically deformable to the wrist part of the tip, like a commercially available arm cover (arm opening), and shrinking it to close the opening. This state where the opening is closed can be easily opened by inserting the arm. Also, the finger part at the tip may be divided into two or three, and the tip may be molded into a glove-like shape to create a sealed structure.
There are no commercially available lead-containing arm sleeves 9, but they can be easily made by cutting off the fingertip portion of a lead-containing glove 54. It is reasonable to mass-produce the lead-containing glove 54 by removing a part (the finger portion) of the mold in which the lead-containing rubber or the like is cast.
Commercially available lead-containing gloves 56 include PR1G manufactured by Protech Lead Eyewear Inc., radiation protection gloves G-3 manufactured by AS ONE Corporation, and Elasto X manufactured by Sanko Chemical Industry Co., Ltd. Alternatively, the gloves disclosed in Patent Document 6 may be used. Patent Document 6 relates to seamless gloves for radiation shielding in the medical field and the like.
The commercially available lead-containing gloves 54 include the glove box gloves, Elastite gloves XL-W, manufactured by Kokugo Co., Ltd. The commercially available round gloveless ports 60 include the round gloveless ports manufactured by Sanplatec Co., Ltd. There are no commercially available oval gloveless ports.

(Overall configuration of standard additional shielding box)
Fig. 1 shows the basic configuration of a standard additional shield box for the under-tube type, Fig. 2 shows the assembly method on-site, and Fig. 3 shows an explanatory diagram of the types of sleeve ports 8 and the correlation between the equipment and protective gear to be attached thereto. In Fig. 1 and Fig. 2, the table 2, X-ray source 33, and patient body 25, which are outside the scope of the box of the present invention, are shown by imaginary lines.
Incidentally, X-ray televisions with the under-tube type X-ray fluoroscopy device structure cited as the knowledge underlying Figures 1 and 2, i.e., a structure in which the X-ray receiver 10 is fixed above the table 2, are not widely sold these days. Around 1970, Toshiba Electric's under-tube type X-ray television DT-AA model and Hitachi's X-ray under-table remote control type cassetteless camera mounted X-ray television EDTP-CA/FA model were sold as general X-ray imaging devices (X-ray televisions).
However, recent X-ray televisions generally have an over-tube structure in which the X-ray source 33 is fixed above the table 2 as a general X-ray imaging device and the X-ray receiver 10 is fixed below the table 2. Since there are issues to be considered regarding the over-tube type additional shielding box, it will be devised separately and is not included in the present invention.
On the other hand, even recently, many X-ray fluoroscopy devices using an under-tube structure such as a C-arm type are sold and widely used for angiography devices for IVR. An embodiment of the present invention using a C-arm type or an evolved version of the C-arm type, which has a somewhat complicated structure because the X-ray receiver 10 is not fixed, will be described later.
It should be noted that the present embodiment is intended to provide an easy-to-understand explanation of the structure of a standard additional shielding box in an under-tube type that uses a sight glass for viewing the inside up close, a glove port for operating the inside up close, and a sleeve structure.

(Explanation of a bird's-eye view of a standard additional shielding box)
The standard type additional shield box of the present invention will be explained using the bird's-eye view of Figure 4. In the bird's-eye view of Figure 4, the shape of the table is not the stationary type shown in phantom lines in Figures 1 and 2, but is an island type shown in solid lines for easy understanding and viewing, the same as in the drawings of the embodiments described below. Also, the drape etc. 22 is shown in a state before being lifted by the drape holder 23 to close the patient port 20.
In the additional shielding box 1 of the present invention, shielding members are arranged to three-dimensionally surround the radiation field 15 corresponding to the affected area of the patient. Each member constituting the box has X-ray shielding ability, there is no opening communicating with the outside space, and a medical professional can insert his/her hand into the box through a sleeve structure such as a lead-containing arm sleeve 9 having shielding ability while visually checking the inside from the outside space through the observation window 6 which is a glass plate having shielding ability to perform surgery.
The sleeve structure, such as the lead-containing arm sleeve 9, is made of a flexible material and is attached to the sleeve port 8 of a box or the like when in use.
The patient passes through the box in the direction of the body axis via the patient port 20, placing parts of the body other than the irradiation field and its surroundings, such as the head and limbs, in the external space, and the opening between the box and the body is blocked by a flexible curtain-type drapery or the like 22 with shielding capabilities attached to the patient port 20.
Power, electrical signals, optical signals and liquids are communicated between the inside and outside of the box through a connector 24 having a shielding capability, without any openings.

In the case of the under-tube type, forward scattered X-rays, including small-angle scattered X-rays, can be shielded upward from the irradiation field of the patient's body and its surroundings by using a tabletop 7 made of a material with better shielding performance. Side scattered X-rays from the irradiation field, its surroundings, and other parts can be shielded by a shielding blanket, box, etc., and viewing window 6. Furthermore, by using these materials as a composite absorbing material or an additional composite absorbing material, the scattered X-rays can be attenuated and absorbed.
The under-tube type X-ray receiver 10 can be stored in the box without any openings by assembling the receiver arm 11 between the box body 4 and the end box 5 on-site. The ceiling of the end box 5 is shielded with multiple members to prevent X-rays from leaking. The X-ray source 33 is a portable type whose position and angle can be adjusted and is installed separately below the floor of the box. This improves the image resolution of the X-ray receiver 10, which in turn reduces the X-ray output of the X-ray source.
By performing surgery in a box with no openings and sufficient shielding, as described above, the spatial dose rate in the examination room can be reduced, reducing unwarranted occupational exposure of medical staff and avoiding unnecessary medical exposure to the patient's head, trunk, limbs, etc. In particular, occupational exposure to the head (eyes) of the surgeon can be significantly reduced.

(Option for high energy small angle X-ray scattering)
The third embodiment blocks forward scattered X-rays above the table, including small-angle scattered X-rays having high radiation intensity due to small-angle scattering in the patient's body.

This section explains the basic concept of shielding forward scattered X-rays, including small-angle scattered X-rays with high X-ray intensity. The target is X-rays that are forward scattered in the irradiation field of the patient's body and its surroundings, and forward scattered X-rays with a scattering angle of 35 degrees or less. This slightly impairs the operator's field of vision, but improves the shielding ability for forward scattered X-rays heading toward the operator's head and eyes.
This is achieved by enlarging the area of the top plate 7 shown in the second embodiment. The material of the top plate 7 is the same as that shown in the second embodiment.

As explained in the previous section, the area of the tabletop 7 is expanded to a range irradiated with scattered X-rays having a scattering angle of 35 degrees in the irradiation field.
That is, the tabletop 7 needs to be widened in the vertical direction of the body axis. In order to widen the tabletop 7, the box or the like is installed with the viewing window 6 tilted closer to the vertical, thereby widening the vertical direction of the body axis of the box or the like. This makes the field of view somewhat difficult to see. This ensures a place to install the wide tabletop 7.
In addition, the length of the top plate 7 needs to be extended in the direction perpendicular to the body axis. In particular, the required dimensions require that the end top plate 14 of the end box 5 be lengthened. In order to lengthen the end top plate 14, the end box 5 becomes longer in the direction of the body axis.

As explained above, it can be seen that the areas of the top plate 7 and the end top plate 14 are enlarged and the end box 5 is larger than that of the standard type shown in FIG.
As in the second embodiment, X-ray fluoroscopes having the structure of an under-tube X-ray television are not widely available on the market these days.

(Overall configuration of additional shield box with built-in FPD)
In Example 4, the overall configuration of an additional shielding box with a built-in flat panel detector (FPD) type X-ray receiver 10 that is separate and independent from the X-ray fluoroscope and is stored and installed inside a box or the like and can be moved freely will be described.
FIG. 5 is a diagram showing the overall configuration of an additional shield box with a built-in FPD in an under-tube type in which the X-ray source is disposed under the table.

The problem was that it was difficult to increase the swing range of the X-ray receiver 10 as in the past, and that the surgeon's field of vision in the end box 5 was narrow. Therefore, the solution was to store the X-ray receiver 10 in a box, separate and independent from the X-ray fluoroscopy device. On the other hand, as mentioned above and in the next section, there have been significant technological advances in recent years in the FPDs that are the target of the X-ray receiver 10, and smaller, lighter models are now on the market.

(Development status of FPD)
FPD is a flat panel type X-ray image sensor. Research on FPD started in earnest in the 1990s, and technological development progressed rapidly thereafter. Around 1998, digital general radiography devices using FPD as an X-ray receiver were put on the market. The advantages of FPD compared to CR (Computed Radiography) are that it does not use IP (Imaging Plate) so cassette replacement is not required, the time from shooting to image display is short, and it is close to real-time imaging and can be used for both still images and videos. In addition, compared to DR (Digital Radiography), it can obtain large-area, high-resolution images, and the flexibility of installation location is expanded due to its significantly thinner design. Therefore, it seems that portable radiography devices used in emergency medical care are largely shifting from CR to FPD. However, issues include the high cost of FPD and the high possibility of damage due to dropping.

The X-ray image sensor, which was launched around 1998, has a conversion film 6 that converts the strength of X-rays into an electric signal and a thin film transistor (TFT) that reads the electric signal as its key devices. This is an indirect type FPD (hereinafter referred to as "TFT type FPD") in which a scintillator is laminated on a MOS type image sensor in which amorphous silicon is laminated mainly on a glass substrate and TFTs and photodiodes are integrated. However, this FPD image sensor is difficult to speed up image data processing, as with the CCD sensor described in Example 4, and this tendency becomes even more pronounced in large-area FPDs. Therefore, independent TFT type FPDs are large in mass and can only store data for one shot, so they cannot be used for continuous video shooting. Therefore, independent FPDs that extract image data to a PC or tablet are used for X-ray fluoroscopy observation using a single still image for animals and dentistry, which have small images, as of 2022.

X-ray image sensors that were marketed around 2010 are low-voltage, low-power complementary metal-oxide semiconductor (CMOS) image sensors. Details of the CMOS principle will be shown in Example 4 below. The mechanism of converting electric charges into electrical signals using a photodiode and an amplifier is the same as that of a CCD, but it is a direct conversion method in which X-ray information is directly converted into electrical signals using a semiconductor film. A CMOS image sensor is a substrate-type semiconductor sensor similar to a large-scale integrated circuit (LSI), and is a direct type FPD (hereinafter referred to as a "CMOS type FPD") in which a structure in which one amplifier is paired with one photodiode, and mechanisms such as an amplifier for amplifying signals and a circuit for transferring signals can be built into a single semiconductor. Therefore, an independent CMOS type FPD has a simple and lightweight system as a whole, and can transmit continuously captured video image data directly to a PC, etc.
In the case of the FPD-embedded box of the present invention, if the mass of the built-in independent FPD is large, the overall structure supporting it will be large, so a CMOS type FPD is preferable to a TFT type FPD.

(FPD model and specifications)
Many FPDs use cesium iodide (CsI) scintillator phosphors, and are available with dimensions ranging from 10 inches (25.4 cm) to 17 inches (43.2 cm) on a side. Signal connections can be wired or wireless, and some can be switched between the two by detaching the cable. For wireless connections, the communication standard is a wireless LAN operation method (Wi-Fi) that complies with IEEE802.11n. Regardless of whether wired or wireless, image data can be extracted to a PC or tablet by connecting to a LAN line, and the image can be displayed on a monitor screen or large LCD display screen.
Commercially available TFT-type FPDs that can be used independently with an external X-ray source include (1) FPD1717 TFP-1700A manufactured by Canon Medical Systems, Inc., (2) Digital Radiography DR-ID 1200 manufactured by Fujifilm Corporation, and (3) Digital FPDs "EVS2025C" and "EVS4343" manufactured by DRTEC Corporation. Of these, the detailed specifications of (3) EVS2025C are as follows: scintillator is Csl, signal connection is both wired and wireless, pixel size is 76 μm, external dimensions are width 23 cm × length 28 cm × thickness 1.5 cm, and weight is 1.6 kg. The EVS4343 (3) is a wired connection, but has a large irradiation surface, a pixel size of 140 μm, a resolution of 3072 × 3072 pixels, external dimensions of 43 cm wide × 43 cm long, and a weight of 3.5 kg.
On the other hand, commercially available CMOS type FPDs that can be used independently by an external X-ray source include the CFP2022 and CFP3131, CMOS FPDs for X-ray fluoroscopic imaging devices manufactured by MX Imaging. Both use a Csl scintillator as the X-ray conversion element, a pixel size of 99 μm, and wired signal connection. The X-ray image resolution of the CFP2022 is 2064 x 2036 pixels, the dimensions are 24 cm wide x 29 cm long x 5.5 cm thick, and the weight is 4.54 kg with Pb shielding and about 3 kg without Pb. The X-ray image resolution of the CFP3131 is 3096 x 3096 pixels, the dimensions are 32 cm wide x 37 cm long x 5.5 cm thick, and the weight is 7.72 kg with Pb shielding and about 5 kg without Pb. Other CMOS type FPDs include those manufactured by Teledyne Rad-icon Imaging, which use a Gd ₂ O ₂ S scintillator and weigh in the range of 4 to 8 kg. The detailed specifications are: Rad-icon 2329 has a pixel size of 49 μm and a pixel size of 4608 x 5890, and Rad-icon 3030 has a pixel size of 99 μm and a pixel size of 3096 x 3100.
These commercially available FPDs are sufficiently lightweight and compact, and can be easily connected to an X-ray fluoroscopy device by wired or wireless connection. In the following sections of this invention, the weight of the CFP2022, a CMOS type FPD (weight without Pb is about 3 kg), is used as an example of the FPD to be built into the box.

(Basic concept of FPD built-in type).
In the fourth embodiment, an FPD-embedded box is devised that can house an FPD type X-ray receiver 10 installed separately and independently from an X-ray fluoroscope.
It is considered that X-ray fluoroscopy devices other than FPDs will inherit the functions of conventional X-ray fluoroscopy devices (angio devices).

(Overall configuration of the box with built-in FPD)
The box body 4, sleeve port 8, lead-containing arm sleeve 9, sheet 21, hanging cloth 22, and connector 24 of the FPD-embedded box are the same as those in Example 2, and therefore will not be described in Example 4. The height adjustment rotary knob 38 for adjusting the height of the end face box stand 37 and the end face box 5 are the same as those in Example 2, and therefore will not be described in Example 4. Therefore, the end face box 5, observation window 6, end face top plate 14, and so on of the FPD-embedded box will be described below.

Here is an overview of the box with a built-in FPD. The end face box 5 is not placed on a table, but is supported from the floor by an end face box stand 37 that can be adjusted in height. A slide guide 36 is also attached to the bottom of the end face box 5 so that the end face box 5 can be assembled with the box body 4 on-site. The details of these are explained below.

Next, we will explain the method of shielding the ceiling surface of the box with a built-in FPD. The ceiling of the end box 5 is designed without any penetrating members, so scattered X-rays do not leak out from the extra space created by the movement of the X-ray receiver 10. In other words, the ceiling is sufficiently shielded by the end top plate 14. The concept of shielding by the top plate is as described in Example 2.

Furthermore, a method for assembling the box with a built-in FPD on-site will be described. Since the X-ray receiver 10 is contained inside, there is no receiver arm 11. Since there is no need for an assembly method centered on the receiver arm 11 as in the second to fourth embodiments, there are no particular restrictions on the assembly method for the box with a built-in FPD.
After aligning the position of the X-ray receiver 10 in the end box 5 with the position of the radiation field of the patient's body, the box body 4 is assembled. In Fig. 5, the end box 5 is supported from the floor by an end box stand 37. For example, if the box body 4 and the end box 5 are an integrated structure, it is possible to position one box at a time without assembling two boxes. However, this integrated additional shielding box is a separate device that requires consideration, and is not included in the present invention.
Also, since the number of movable parts inside the box has increased, in FIG. 5 the end plate on the patient's head side of the end box 5 is made into a maintenance end plate 45 which can be attached and detached by means of screws.

Finally, an angiography device to which an FPD-type X-ray receiver 10 of a box with a built-in FPD is connected will be described. Currently, there are no commercially available angiography devices with a separate FPD, but in many cases the FPD itself is connected via a LAN line, so it is possible to switch the FPD by replacing the LAN cable. When using a conventional C-arm type device as is, an X-ray source and an analysis/control device are used without using an FPD-type X-ray receiver.
When using the X-ray fluoroscopy device only for the transmission and fluoroscopy functions, there is no need to use a commercially available angiography device, and the box with the built-in FPD can be used for treatment and examination by using an external X-ray source 33 and a personal computer (PC). The image analysis software for the PC is the one that comes with the FPD.
Commercially available external X-ray sources include the CALNEO XAIR portable X-ray imaging device manufactured by Fujifilm, the HTR9020H medical imaging model manufactured by Mikasa X-Ray, and the NX-100 portable X-ray imaging device manufactured by T&S. These portable X-ray sources are used on casters or the like that can maintain the position and tilt angle. Floor-mounted external X-ray sources with a function to determine the position and angle are to be devised separately as there are issues to be considered, and are not included in the present invention.

Fig. 5 shows the overall configuration of an additional shield box 1 with a built-in FPD. The front and side views of Fig. 5 are shown in cross section as viewed from the arrows A-A and B-B. The central part of the plan view shows the internal structure with cut lines. In Fig. 5, the table 2, patient body 25, and X-ray source 33, which are outside the scope of the box of the present invention, are shown with imaginary lines. The movement range of the X-ray receiver 10 and X-ray source 33 of the FPD system are shown with imaginary lines in the front and side views.
As explained above, there are almost no changes to the box body 4 as in the previous embodiment. The end face box 5 has a simpler structure than the standard type shown in Fig. 2 of embodiment 2. Since there is no structure penetrating the ceiling of the end face box 5, the ceiling can be easily shielded by the end face top plate 14.
Furthermore, since there is no receiver arm 11 near the box, there is no obstacle on the side of the box, making it easier to access the box and making it easier to perform medical procedures during surgery.
It should be noted that the present embodiment is intended to simply explain the structure of an additional shield box with a built-in FPD in an under-tube type that uses a peephole for viewing the inside at close range, a glove port for operating the inside at close range, and a sleeve structure.

(Bird's-eye view of the additional shield box with built-in FPD)
The additional shield box (box) with a built-in FPD of the present invention will be described with reference to the bird's-eye view of Fig. 6. The box with a built-in FPD will be described by repeating the above contents.
In the additional shielding box 1 of the present invention, shielding members are arranged to three-dimensionally surround the radiation field 15 corresponding to the affected area of the patient. Each member constituting the box has X-ray shielding ability, there is no opening communicating with the outside space, and a medical professional can insert his/her hand into the box through a sleeve structure such as a lead-containing arm sleeve 9 having shielding ability while visually checking the inside from the outside space through the observation window 6 which is a glass plate having shielding ability to perform surgery.
The sleeve structure, such as the lead-containing arm sleeve 9, is made of a flexible material and is attached to the sleeve port 8 of a box or the like when in use.
The patient passes through the box in the direction of the body axis via the patient port 20, placing parts of the body other than the irradiation field and its surroundings, such as the head and limbs, in the external space, and the opening between the box and the body is blocked by a flexible curtain-type drapery or the like 22 with shielding capabilities attached to the patient port 20.
Power, electrical signals, optical signals and liquids are communicated between the inside and outside of the box through a connector 24 having a shielding capability, without any openings.
In the case of the under-tube type, forward scattered X-rays, including small-angle scattered X-rays, can be shielded upward from the irradiation field of the patient's body and its surroundings by a tabletop 7 made of a material with better shielding performance. Side scattered X-rays from the irradiation field and other parts can be shielded by a shielding blanket, box, etc., and viewing window 6. Furthermore, by using these materials as a composite absorbing material or an additional composite absorbing material, the scattered X-rays can be attenuated and absorbed.
In the box with built-in FPD, the front panel detector (FPD) type X-ray receiver 10 and the moving mechanism are all stored in the box. The FPD is an independent, single X-ray flat panel detector. The X-ray source 33 is a portable type with adjustable position and angle, which is installed separately below the floor of the box. Since there is no object penetrating the ceiling of the end box 5, forward scattered X-rays can be reliably shielded by the end top plate 14. This improves the image resolution of the X-ray receiver 10, which in turn reduces the X-ray output of the X-ray source. In addition, since there is no receiver arm, there is no equipment around the box that would interfere with the operation, so medical personnel can easily perform the operation in a spacious space.
By performing surgery in a box with no openings and sufficient shielding, as described above, the spatial dose rate in the examination room can be reduced, reducing unwarranted occupational exposure of medical staff and avoiding unnecessary medical exposure to the patient's head, trunk, limbs, etc. In particular, occupational exposure to the head (eyes) of the surgeon can be significantly reduced.

(Example 1 of the composite absorbent material of Patent Document 1)
In Patent Document 1, which is written by the same inventor, a composite absorbing material that effectively attenuates and absorbs scattered X-rays is proposed. The composite absorbing material is placed on the surface irradiated with scattered X-rays from the patient's body, and the composite absorbing material is intended to reduce re-scattering of scattered X-rays by absorbing the linear energy of the incident scattered X-rays after maximally efficiently attenuating the linear energy. Due to attenuation and absorption by the composite absorbing material, the X-rays are extinguished by converting their energy into kinetic energy such as photoelectrons. The composite absorbing material is mainly composed of a low-reflection attenuation layer (first layer) such as lead (Pb) and a multilayer absorbing layer (one to three pairs of diffusion absorbers and electronic absorbers). In other words, the composite absorbing material attenuates and absorbs scattered X-rays from scatterers such as human tissues and tables by a material in which three or more layers with different roles are closely adhered to each other in a multilayer structure.

The principle of composite absorbing materials will be explained. Composite absorbing materials are primarily intended for scattered X-rays that have been scattered multiple times by a substance, and have energies of less than 88 KeV, but are primarily intended for a slightly lower energy range.
When X-rays interact with matter in the photoelectric region, much of the incident X-rays are absorbed in linear energy due to the photoelectric effect. When the energy of the incident X-rays exceeds the absorption edge, the photoelectric effect causes the emission of photoelectrons, characteristic X-rays, and Auger electrons. In addition, bremsstrahlung radiation from these electrons generates bremsstrahlung X-rays. In the slightly higher energy region near the absorption edge, peculiar absorption occurs, in which there is significant photoelectric absorption.
The first low-reflection attenuation layer, Pb, has good linear attenuation of most of the incident X-rays and good linear energy absorption. The K absorption edge of Pb is 88 KeV, and the L absorption edge is about 13 to 16 KeV. In other words, even in the case of medical X-ray equipment, characteristic X-rays (L-X-rays) due to the L absorption edge of about 10.5 to 14.8 KeV are emitted from the surface of Pb.
In the energy region between the K absorption edge and L absorption edge of Pb (17 to 87 KeV), specific absorption occurs in elements with atomic numbers of 37 or more and less than 81, and significant photoelectric absorption occurs in the energy region slightly higher than the K absorption edge of the element and between the K absorption edge.
The multilayer absorber layer utilizes specific absorption to efficiently annihilate X-rays by using pairs of diffuse absorbers and electron absorbers. Elements with an electron absorption rate of less than 70% at a certain monochromatic energy in this energy range (e.g., 60/50/40/30/20 KeV) are extracted as diffuse absorbers. The linear attenuation coefficient μ, linear energy absorption coefficient μen, and electron absorption rate (μen/μ) at monochromatic energy are shown in Table 3.
The diffuse absorber undergoes significant ray attenuation and significant ray energy absorption due to the specific absorption at the K-absorption edge, but because it is an element with an electronic absorption rate of less than 70%, it also re-emits certain secondary X-rays (characteristic X-rays, braking X-rays). In other words, in addition to absorption, it also plays a role in diffusing and pushing back attenuated photons to the surrounding layers (i.e., moving them in a zigzag pattern for a longer distance in the thin material layer) by re-emitting secondary X-rays in various directions.
The electron absorber is an element with an atomic number of 11 or more and 82 or less that absorbs secondary X-rays, etc., and has good linear energy absorption of X-rays at the specific energy at which the diffuse absorber is extracted, i.e., an element that has good electron absorption with an electron absorption rate of 70% or more.
That is, by having a diffusion absorber and an electronic absorber coexist as a pair, the X-rays are diffused and pushed back within the thin material layer, where they are absorbed electronically as they travel back and forth multiple times.
In the multilayer absorption layer, one to three pairs of diffusion absorbers and electron absorbers are stacked tightly together, allowing the X-rays to be efficiently annihilated as they travel back and forth repeatedly within the thin, multi-layered material, and converted into kinetic energy such as photoelectrons.

The materials used in the composite absorbent material are described.
The low reflection attenuation layer (first layer) is set to Pb of 0.1 to 0.3 mm.
For a pair of multilayer absorption layers, elements (materials) that form a pair of a diffusion absorber and an electron absorber are set based on the value of the linear energy absorption coefficient μen and the electron absorption ratio (μen/μ) at any monochromatic energy set other than the K absorption edge.
When the energy of the monochromatic energy for which the diffusion absorber is set is 50 KeV, the element or compound for which the electron absorption ratio μen/μ at 50 KeV in Table 3 is less than 70% and which is used as the diffusion absorber is Sn or Ba. The element or compound for which the electron absorber is paired with the element or compound for which the electron absorption ratio is 70% or more is Fe, Cu, Nb, or Mo. W or Pb can be placed as the electron absorber, or if there is one placed in an adjacent layer, it can be integrated by combining it with the other role.
When the energy of the monochromatic energy for which the diffusion absorber is set is 30 KeV, the element or compound for which the electron absorption ratio μen/μ at 30 KeV in Table 3 is less than 70% and which is the diffusion absorber is Nb, Mo, or Sn. The element or compound for which the electron absorber is paired with the element or compound for which the electron absorption ratio is 70% or more is Ti, Fe, or Cu. Ba, W, or Pb can be placed as the electron absorber, or if there is one placed in an adjacent layer, it can be integrated by combining it with the other role.

Next, the operation of setting the combination of the diffusion absorber and the electron absorber in the entire multilayer absorber layer (the design method of the multilayer absorber layer) will be described. The electron absorption region is the X-ray energy region where the electron absorption ratio (μen/μ) of each element is 70% or more. Separately, the photon emission region is the region where this ratio is less than 70%. These are set for the monochromatic X-ray energy shown in the NIST database in Table 3.
For the first layer that is irradiated with scattered X-rays of less than 88 KeV from a scattering medium (body tissue, a table, a filter, etc.), Pb is used, which has low scattering in this energy region.
For example, for the first diffusion absorber in the second layer, 40 to 60 KeV (median: 50 KeV) is intentionally targeted, and an element that is in a separate photon emission range in this region, such as Sn, is used.
For the third layer of electron absorber opposite to the second layer, an element in the electron absorption region in the 50 KeV region, such as Mo or Nb, is used. Although the thickness increases, Cu or Fe may also be used.
For example, for the second diffusion absorber in the fourth layer, 20 to 40 KeV (median: 30 KeV) is intentionally targeted, and an element such as Nb or Mo that is in a separate photon emission range in this region is used.
The fifth layer, which is opposite to the fourth layer, is made of an element having an electron absorption range of 30 KeV, such as Cu or Fe. Depending on the conditions, Al, Si, or Ti may be used. Since the K-absorption edge of Ti is 4.96 KeV, the K-absorption edge of the element constituting the diffusion absorber of the multilayer absorber layer is necessarily 5 KeV or higher.
With the above configuration, scattered X-rays with energy less than 88 KeV can be annihilated and converted into kinetic energy of electrons.

The composite absorbing material is one of the main materials constituting the structure of the present invention. By using the composite absorbing material, the radiation dose rate in the space such as a medical room can be reduced. This makes it possible to improve the image quality of the X-ray receiver and to appropriately minimize the exposure of patients and medical staff. The structure of the basic case of the composite absorbing material is explained in FIG. 7.
Fig. 7 shows the basic case configuration consisting of only a Pb low reflection attenuation layer (first layer) and a multilayer absorbing layer (1 to 3 pairs) when the outermost layer of the multilayer absorbing layer is made of Al, Si, Mg, etc., which have low fluorescence yield and low energy of generated characteristic X-rays. In Fig. 7, a. is an explanatory diagram of the configuration, b. shows a composite absorbing material in which the multilayer absorbing layer has two pairs of diffusion absorbers and electron absorbers for a total of five layers, c. shows a composite absorbing material in which the multilayer absorbing layer has three pairs of diffusion absorbers and electron absorbers for a total of seven layers, and d. shows a composite absorbing material in which the multilayer absorbing layer has one pair of diffusion absorbers 91 and electron absorbers for a total of three layers.
Examples of material combinations here are Pb-Sn-Nb-Cu-Al for a total of 5 layers, Pb-Ba-Sn-Nb-Cu-Fe-Al for a total of 7 layers, and Pb-Nb-Si for a total of 3 layers. By combining Fe and Cu, which are combinations of elements with similar characteristics, the total of 7 layers may be Pb-Ba-Sn-Nb-Cu-Al and a total of 6 layers.
In the portion where the composite absorbing material is used, the low reflection material described in the first embodiment may be used as a second best measure, although the effect of reducing scattered X-rays is reduced.

(Basic structure of composite absorbent material)
FIG. 7 shows a basic case diagram of a composite absorbing material. a shows an outline of the configuration, b shows an example of a composite absorbing material 72 with two pairs for a total of five layers 74, c shows three pairs for a total of seven layers 75, and d shows one pair for a total of three layers 76. The low reflection attenuation layer 80 is Pb in the case of the composite absorbing material 72. In the case of the additional composite absorbing material 73, the linear attenuation material 70 or the low reflection attenuation material 71 is used instead of the low reflection attenuation layer 80. Note that the number of pairs of diffusion absorbers 78 and electron absorbers in the multilayer absorbing layer 77 is indicated. In these figures, the diffusion absorbers 78 and electron absorbers 79 that make up pairs are connected by dashed lines, and the numbers of the pairs in each of a to c are indicated as (1) to (3). Although example element symbols are shown in parentheses in the figures, these are illustrative and do not limit the present invention.

1. Additional shield box 2. Table 3. Table support 4. Box body 5. End box 6. Viewport 7. Top plate 8. Sleeve port
9. Sleeve 10. X-ray receiver 11. Receiver arm 12. Connection flange 13. Receiver port 14. End surface top plate 15. Radiation field 20. Patient port 21. Coverlet, etc. 22. Drape, etc. 23. Drape holder 24. Connection connector 25. Patient body 26. Guide rail 27. Presser plate 28. Side end opening 29. Connection flange cover 33. X-ray source 36. Slide guide 37. End surface box stand 38. Height adjustment rotation knob 39. Rack and pinion 40. X-ray receiver (FPD)
41. Portable X-ray source 42. X-ray source stand 45. Maintenance end plate 46. Rail 50. Large diameter port 51. Small diameter port 52. Fastening band 53. Lead arm sleeve 54. Lead glove 55. Lead arm cover 56. Lead glove 57. Band 58. Housing 59. Screw 60. Gloveless port 61. Slide mechanism 64. Cart 65. Vertical axis rotation mechanism 66. Tie band 70. Linear attenuation material 71. Low reflective attenuation material 72. Composite absorbing material 73. Additional composite absorbing material 74. Composite absorbing material (basic case, total of 5 layers)
75. Composite absorbent material (basic case, total of 7 layers)
76. Composite absorbent material (basic case, all three layers)
77. Multi-layer absorber layer 78. Diffuse absorber 79. Electronic absorber 80. Low reflection attenuation layer

Claims (15)

In the additional shield for radiation protection, which is installed on the top of the table of a medical X-ray radiography device, the main structure of the rectangular box has a structure that can be divided into two or more parts in the body axis direction ,
One or more shielding materials capable of shielding X-rays irradiated to each part are used as constituent materials of the box or as members arranged on its surface,
The member is disposed so as to surround the radiation field of the patient in a three-dimensional manner;
An additional shielding box, characterized in that a device for visually inspecting the inside of the box at close range and a device for operating the inside of the box with respect to the patient's body or devices and items required for medical treatment are attached to the box.
The additional shield box, which is a rectangular additional shield that is the main structure in claim 1, is characterized in that the components are installed to surround the patient's radiation field in three dimensions, and there are no openings that cannot reduce the transmission of X-rays in any direction from the patient's radiation field, except for the X-ray entrance. The additional shielding box according to claim 1, characterized in that the device for viewing the inside at close range is a peephole made of one or more shielded glass plates or shielded resin plates having transparency that allows viewing from the ceiling or wall of the box. The additional shielding box according to claim 1, characterized in that the device for operating the inside in close proximity is one or more flexible sleeve structures attached to sleeve ports on the wall of the box. In the above-mentioned claim 1, the rectangular box is
selecting two or more combinations of the type and thickness of the shielding material according to the value of the radiation energy irradiated to each portion;
By using the box as a structural material or a member disposed on its inner surface,
An additional shield box characterized by effectively attenuating scattered X-rays from the patient's body. In the additional shielding box according to claim 1, in the under-tube type X-ray fluoroscope,
For forward scattered X-rays in the high energy range, including small-angle scattered X-rays with radiation energy of 88 kiloelectron volts or more generated from the patient's irradiation field and its surroundings, which are irradiated at a scattering angle of 35 degrees or less relative to the incident angle,
Among the shielding materials, a radiation attenuation material consisting of a simple substance or a compound of an element having an atomic number of 83 or more and 92 or less is arranged on the top plate of the ceiling part of the box, which is a member in the range irradiated with forward scattered X-rays, so that the radiation attenuation material can be obtained without generating characteristic X-rays of the K shell.
Additional shielding box characterized by linear attenuation of forward scattered X-rays In the additional shielding box of claim 2, the rectangular box is
The patient's body is passed through the patient port at the end of the rectangular box, which is the main structure, in the direction of the body axis, so that the patient's body parts, except for the area near the irradiation field, are placed in the external space.
By covering the opening with a flexible shielding sheet that has shielding capabilities,
An additional shielding box that reduces the spatial dose rate within the installation room and protects areas other than the area near the patient's radiation field from medical exposure. In the additional shielding box of claim 2, in the under-tube type X-ray transmission device,
The receiver arm of the X-ray receiver is mounted in the receiver port of the box;
By assembling the split boxes together,
An additional shielding box for housing an X-ray receiver within said box. In the additional shielding box of claim 6,
By installing a composite absorbing material in which three or more layers are closely stacked in a multilayer structure, the first layer being a low reflection attenuation layer made of an element or linear attenuation material having an atomic number of 82 or more, and the second layer being a multilayer absorbing layer made of a pair of a diffusion absorber and an electron absorber,
An additional shield box characterized by effectively absorbing the linear energy of scattered X-rays after linearly attenuating the scattered X-rays The multi-layer absorbent layer added to the composite absorbent material in the additional shielding box of claim 9 is
The additional shield box is characterized in that a structural material made of titanium alloy and/or aluminum alloy, which is the base material of the box, is placed in close contact with the surface on the X-ray entrance side, and the structural material is used as an electron absorber in the outermost layer of the composite absorber material, thereby attenuating scattered X-rays and absorbing their linear energy more effectively. In the additional shielding box of claim 4, the rectangular box is
The medical worker inserts his/her arm into the box through a sleeve port to place the medical worker's body part other than the arm in the external space;
The flexible sleeve structure having a shielding capability is attached to the sleeve port to close the opening between the box and the medical staff,
An additional shielding box that reduces the spatial dose rate in the room in which it is installed and protects the hands and arms of medical personnel from occupational exposure. In the additional shielding box according to claim 1 or 2,
An additional shielding box characterized in that signals and items such as power sources, electric signals, and liquids used in surgery in the box are communicated through the box by a shielding connector attached to a connection port of the box, and the signals and items can be transferred between the inside and outside of the box while maintaining shielding without providing an opening. In the additional shielding box according to claim 3, in the under-tube type X-ray fluoroscopy device,
an X-ray receiver is disposed inside the box;
The box has no openings leading to the outside space in any direction,
A linear attenuation material is placed on the top plate of the box so that the effective energy of small-angle scattered X-rays is equal to or lower than the K absorption edge.
An additional shield box characterized by effectively attenuating upward scattered X-rays toward the surgeon's crystalline lens. In the additional shielding box of claim 6,
When the radiation energy of the forward scattered X-rays is 88 KeV or more,
In order to block forward scattered X-rays with positive and negative scattering angles of less than 35 degrees from the vertical,
The linear attenuation material of the top plate having an atomic number of 83 or more is expanded in width in accordance with the scattering angle,
The shielding ability of the observation window can be increased by increasing the path length by tilting the observation window closer to the vertical or by increasing the incident angle of the forward scattered X-rays.
An additional shield box characterized by more effective attenuation of upward scattered X-rays toward the surgeon's crystalline lens. In the additional shielding box according to claim 1 or 2, in the under-tube type X-ray fluoroscopy apparatus,
an X-ray receiver is disposed inside the box;
The X-ray source is placed under the table on which the patient lies so as to be paired with the X-ray receiver;
The primary X-rays from the X-ray tube are directed in a straight line toward the patient's body,
Additional shielding box characterized by reduced radiation dose and radiation protection load and allowing X-ray fluoroscopy