JPH0813090B2 - Radiation image reading method and apparatus - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for reading radiation image information stored and recorded in a radiation image conversion panel having a stimulable phosphor, and more specifically, it relates to a method for reading efficiency. The present invention relates to a good radiation image information reading method and apparatus.

[Technical background of the invention]

Radiation images such as X-ray images are often used for disease diagnosis. In order to obtain this X-ray image, X-rays that have passed through the subject are irradiated onto the phosphor layer (fluorescent screen), thereby generating visible light, and this visible light is used in the same way as when taking a normal photograph. A so-called radiograph in which a film using salt is irradiated and developed is used. However, in recent years, a method has been devised for directly taking out an image from the phosphor layer without using a film coated with a silver salt.

As this method, the radiation that has passed through the subject is absorbed by the phosphor, and then the phosphor is excited by, for example, light or thermal energy so that the radiation energy accumulated by the absorption by the phosphor is emitted as fluorescence. , There is a method of imaging by detecting this fluorescence. Specifically, for example, U.S. Pat. No. 3,859,527 and JP-A-55-121.
No. 44 discloses a radiation image conversion method using a stimulable phosphor and using visible light or infrared light as stimulated excitation light. This method uses a radiation image conversion panel in which a stimulable phosphor layer is formed on a support, and the radiation transmitted through the subject is applied to the stimulable phosphor layer of this radiation image conversion panel to apply the radiation to each part of the subject. A latent image is formed by accumulating the radiation energy corresponding to the radiation transmittance, and thereafter, the stimulable phosphor layer is scanned with stimulable excitation light to radiate the accumulated radiation energy of each part to generate a latent image. Convert it to light,
A radiation image is obtained by an optical signal depending on the intensity of the light.

The radiation image is visualized as it is or after being subjected to image processing in real time and output to a silver salt film, CRT or the like. Further, the radiation image is stored in an image storage device such as a semiconductor storage device, a magnetic storage device, and an optical disk storage device, and thereafter, is taken out of the image storage device as needed, output to a silver halide film, a CRT, or the like to be visualized. May be.

The radiation image conversion panel in the radiation image conversion method as described above is generally prepared in several sizes similar to the screen and film used in the usual radiography method, and the size of the object Therefore, the photographer selects and uses it.

However, when there are several types of radiation image conversion panels, there are the following drawbacks.

(1) The manufacturing cost of the radiation image conversion panel increases.

(2) It is troublesome for the photographer to select an appropriate radiation image conversion panel each time a radiographic image is captured and set it on the imaging device.

(3) It is necessary to manage a large number of radiation image conversion panels having different sizes.

(4) Since the radiation image capturing device, the reading device, the erasing device, the stock device, etc. have to be compatible with the radiation image conversion panels of various sizes, the transport mechanism, the reading mechanism, the erasing mechanism, the stock mechanism, etc. are complicated and the device Becomes larger.

In general radiography, the subject is sufficiently smaller than the radiation image conversion panel, and the radiation field (radiation irradiation region) is narrowed down for the purpose of reducing the exposure dose to the subject.

However, in the above-described radiation image conversion method, the radiation image is read on the entire surface of the radiation image conversion panel, and there are the following drawbacks.

(1) The required radiation image information is smaller than the read radiation image information, and the utilization efficiency of the image storage device is reduced, or the processing time such as image processing becomes long.

(2) Since the unnecessary portion is read, the reading time becomes long.

(3) The resolution of the radiation image of a necessary portion is relatively reduced.

(4) When a radiation image is output on a silver salt film or a CRT for visualization, a necessary radiation image and an unnecessary image are mixed to make the image extremely difficult to see, and the diagnostic ability deteriorates.

As a way to improve the above-mentioned drawbacks, JP-A-60-32044
JP-A No. 2003-242242 discloses a radiation imaging apparatus that optically scans only the imaged area (radiation irradiation area) on the radiation image conversion panel that has been radiographed with the stimulating excitation light to read the radiation image. The method using this device is preferable because it is not necessary to manage a large number of radiation image conversion panels of different sizes, and the respective mechanisms such as the radiation image capturing, reading, and erasing device are simplified and the device is downsized. Further, in the method using this apparatus, it is not necessary to read even unnecessary portions on the radiation image conversion panel that have not been radiographed, so that the reading time can be shortened, necessary radiation image information can be reduced, and image processing etc. can be speeded up. Has been preferred.

However, in the above method, since the radiation image is read by optically scanning only the radiation irradiation area on the radiation image conversion panel, it is necessary to control the light deflector, the sub-scanning unit, etc. for each imaging area of an arbitrary size. However, it has the drawback that the reader is significantly complicated. Further, since the method performs optical scanning in accordance with a radiation irradiation area of an arbitrary size,
It is necessary to move a sync signal generator (photodetector) for obtaining a horizontal sync signal when reading a radiation image for each radiation irradiation area, which also complicates the reading device.

[Object of the Invention]

The present invention has been made in view of the above-mentioned drawbacks in a radiation image reading method using a radiation image conversion panel, and an object of the present invention is a radiation image reading method capable of reducing unnecessary radiation image information. To provide.

Another object of the present invention is to provide a radiation image reading method capable of shortening the radiation image reading time.

Another object of the present invention is to provide a radiation image reading method capable of obtaining a plurality of radiation images having different sizes from one radiation image conversion panel.

Another object of the present invention is to provide a radiation image reading method that does not require handling of a large number of radiation image conversion panels of different sizes and that allows the radiation image reading device and the like to be small and simple.

Another object of the present invention is to provide a radiographic image reading method in which the optical scanning region of the stimulated excitation light is constant regardless of the radiation irradiation region, and the reading device is small and simple.

Another object of the present invention is to provide a radiation image reading method in which a horizontal synchronizing signal can be easily obtained regardless of the radiation irradiation area.

A further object of the present invention is to provide a radiation image reading apparatus that can realize the above method.

[Structure of Invention]

In order to achieve the above-mentioned object, the inventors of the present invention have conducted extensive studies on a radiation image reading method using a radiation image conversion panel having a stimulable phosphor layer and a radiation image reading apparatus using this radiation image reading method. Came.

As a result, the radiation image reading method which is the object of the present invention, the radiation image conversion panel provided with a stimulable phosphor layer is irradiated with radiation to accumulate and record radiation image information, and then the radiation image conversion panel is excited. A radiation image reading method for scanning in a main scanning direction and a sub-scanning direction with a beam light to convert the radiation image information into stimulated emission light, and photoelectrically reading the stimulated emission light with a photodetector to obtain a radiation image. In the radiation image conversion panel of a predetermined size prepared regardless of the subject size, in accordance with the subject size, a radiation irradiation region for irradiating the radiation or a reading designation for reading the stored radiation image information After setting one of the regions and setting the other region according to the setting, the radiation image information is irradiated by irradiating only the radiation irradiation region with the radiation. The excitation beam light is scanned over the entire surface of the radiation image conversion panel in the main scanning direction and outside the designated reading area with respect to the scanning density of the designated reading area in the sub scanning direction. Of the signals output from the photodetector by the scanning by scanning so that the scanning density of
This can be achieved by a radiation image reading method characterized in that a radiation image is obtained by selecting only signals corresponding to the designated reading area to obtain radiation image signals.

Further, a radiation image reading apparatus which is an object of the present invention is provided with a radiation image conversion panel having a stimulable phosphor layer for storing and recording radiation image information obtained by irradiating a subject with radiation, and prepared regardless of the subject size. Depending on the subject size, either the radiation irradiation area for irradiating the radiation or the read designation area for reading the stored and recorded radiation image information is set and input to the radiation image conversion panel having a predetermined size. Input means, means for setting the other area according to the area set by the input means, a radiation source controlled to irradiate the radiation only to the radiation irradiation area, and the radiation image conversion panel Excitation beam light scanning means for scanning the excitation beam light in the main scanning direction and the sub-scanning direction, and The excitation beam light scanning is performed so that the entire surface of the radiation image conversion panel is scanned and scanning is performed so that the scanning density outside the designated reading area is smaller than the scanning density of the designated reading area in the sub-scanning direction. Scanning control means for controlling the means, a photodetector for photoelectrically converting stimulated emission light generated by scanning the excitation beam light into an electric signal, and a signal output from the photodetector, Processing means for selecting and extracting only signals corresponding to the designated reading area;
It is achieved by a radiation image reading device characterized by having.

 The present invention will be described in detail below.

In the present invention, in order to irradiate a predetermined area of the radiation image conversion panel with radiation and to make only the electric signal within the specified area the radiation image information, the radiation image reading device reads the corresponding area. The area may be set in advance. That is, in the method, an individual reading area of a reading device having a plurality of reading areas and a plurality of designated areas for irradiation of radiation corresponding to the respective reading areas are set in advance, and one of the designated areas is irradiated with radiation. The radiation image information is obtained by irradiating the image data and reading it by the reading area corresponding to the designated area.

The reading area in the present invention is an area in which an electric signal obtained by optical scanning of stimulated excitation light is selected as radiation image information. This reading area will be described with reference to FIG.

In the figure, 11 is a radiation image conversion panel, 12, 13 and 14 are designated regions for irradiation of a plurality of radiations, and 15 is a scanning line for representing a state of optical scanning of stimulated excitation light in the main scanning direction. . The state of optical scanning in the sub-scanning direction of the present invention will be described later. In the method of the present invention, in order to simplify the size of the radiation image reading apparatus, regardless of the size of the radiation irradiation area or the designated area, the optical scanning of the stimulated excitation light in the main scanning direction covers almost the entire surface of the radiation image conversion panel 11. It is done to include. The stimulated emission generated by the optical scanning of the stimulated excitation light is photoelectrically converted into a time-series electric signal, which corresponds to one designated area selected at the time of the radiation irradiation of the electric signal. Only the electric signal in the defined area (reading area) is selected and extracted as the radiation image information.

Various methods are conceivable for selectively extracting only the electric signal in the reading area from the time-series electric signal as radiation image information, but particularly, the conversion (sampling) start position and end of the analog / digital converter are ended. Control the position,
A method of digitizing and taking out only the electric signal in the reading area, and a method of digitizing all the signals and then selectively taking out only the digital signal in the reading area are preferable.

Next, the optical scanning in the sub-scanning direction of the present invention will be described with reference to FIGS. 1 (b) and 1 (c). As shown in 15 of the figure, the sub-scanning portion (P and Q in the figure) other than the reading area of the radiation image conversion panel 11 is increased in area by increasing the sub-scanning speed to a high speed, compared to the designated reading area. The outer scanning density is reduced. For example, as shown in FIG. 1C, main scanning may not be performed in the sub-scanning portion other than the reading area.

In the present invention, when irradiating a predetermined area with radiation, the radiation irradiation area does not necessarily have to be included in the specified area, as long as the area of interest of the subject is included in the specified area. In order to reduce the exposure dose to the radiation irradiation area, it is preferable that the radiation irradiation area is included in the designated area. However, in the present invention, the radiation irradiation area is narrowly referred to only as a portion that is truly irradiated with radiation, and is broadly referred to as a true radiation irradiation portion and its peripheral portion.
However, the area of the peripheral area is 50% of the area of the true radiation irradiation area.
The following is preferred.

In the present invention, the stimulable phosphor is, after being irradiated with light or high-energy radiation, optical, thermal, mechanical,
It refers to a phosphor that shows stimulated emission corresponding to the irradiation dose of the first light or high-energy radiation by optical or electrical stimulation (stimulated excitation), but from a practical viewpoint, it is preferably 500 nm or more. It is a phosphor that emits stimulated emission by stimulated excitation light.

In the present invention, the stimulable excitation light is a light that can efficiently release the radiation energy accumulated in the stimulable phosphor as stimulated emission, preferably Ar laser, He-Ne laser, Kr laser, YAG Lasers such as lasers, He-Cd lasers, and semiconductor lasers can be used.

〔Example〕

Next, the present invention will be described in more detail and specifically with reference to Examples.

FIG. 2 is a schematic diagram of a radiation image reading method according to an embodiment of the present invention, in which a radiation irradiation area is designated in advance during radiation irradiation.

In FIG. 2, 21 is an imaging device, 22 is a radiation source, 23 is a radiation image conversion panel according to the present invention, 24 is a plurality of frames drawn on the imaging device for previously designating a radiation irradiation area,
25 is a radiation image reading device capable of reading the region of the radiation image conversion panel 23 corresponding to the region designated by the plurality of frames, 26 is a controller for operating the system, 27 is a keyboard for manually inputting , 28 are radiation image reproducing devices.

Radiation from the radiation source 22 is limited to a radiation irradiation area by operating a diaphragm (not shown), and is irradiated to one of the areas 24C designated in advance by the frame 24. Information regarding the designated area 24C is input from the keyboard 27 and transmitted to the controller 26, and the reading area of the reading device 25 is determined.

In this case, the aperture of the radiation source 22 may be automatically narrowed by the information input from the keyboard 27 to limit the radiation irradiation area. The radiation image information read by the reading device 25 is visualized by the radiation image reproducing device 28. In the present embodiment, the means for transmitting information regarding the designated radiation irradiation area is not limited to the above. Further, the parts 21 to 28 may be integrated or separated.

Next, the mechanism of reading radiation image information from the radiation image conversion panel according to the present invention will be described.

FIG. 3 is a schematic view of an embodiment of the radiation image reading method of the present invention.

In FIG. 3, 3A is an imaging unit, 301 is a radiation source, 302 is a subject, and 303 is a radiation image conversion panel.
3B is a reading unit, 304 is a stimulated excitation light source, 306 to 310 are optical scanning systems, 312 is a stimulated emission condensing body, and 313 is a photoelectric converter.

Radiation that has passed through the subject 302 in 3A and has been irradiated to one of a plurality of regions designated in advance is absorbed by the radiation image conversion panel 303, and a part of the energy is stored in the stimulable phosphor. . The radiation image conversion panel having one of the designated areas irradiated with radiation in 3A is sent to the reading unit 3B.

In the reading unit 3B, the reading area control unit 315 is configured to perform analog / analog based on the specified area information from the keyboard 316.
By giving a signal to the digital converter 314 to control the sampling start position and the sampling end position, the reading area is designated and the radiation image information is obtained. The signal selected by the analog / digital converter 314 is sent to a radiation image reproducing unit (not shown) to be visualized.

In the above embodiment, the reading area is an analog / digital converter.
Although only 314 is controlled and designated, the analog / digital converter, the sub-scanning mechanism 311, the light deflector 308, etc. may be controlled simultaneously. Further, the photographing unit and the reading unit may be integrated.

〔The invention's effect〕

As described above, according to the present invention, there is little unnecessary image information in the obtained radiation image information, so that the utilization efficiency of the image storage device is improved.

Further, according to the present invention, the radiation image information obtained has a small amount of unnecessary image information, so that processing time such as image processing is shortened.

Further, according to the present invention, the radiation is irradiated only to the radiation irradiation region, and the radiation exposure amount to the subject such as the patient can be suppressed to a necessary minimum, which leads to a reduction in risk due to the radiation exposure.

Further, according to the present invention, it is not necessary to read an unnecessary portion, so that the reading time of the radiation image conversion panel is shortened.

Further, according to the present invention, when a radiation image is visualized, unnecessary images are not mixed, so that the image is easy to see and the diagnostic ability is improved.

Further, according to the present invention, it is not necessary to select the size of the radiation image conversion panel depending on the size of the subject, and the complexity is eliminated.

Further, according to the present invention, since it is not necessary to select the size of the radiation image conversion panel depending on the size of the subject, the size of the radiation image conversion panel becomes one type, and the radiation image capturing device, the reading device, and the erasing device. , The stock device is simplified and downsized.

Further, according to the present invention, the optical scanning area in the main scanning direction of the stimulated excitation light is constant regardless of the size of the reading area of the radiation image, the configuration of the reading device is simplified, and high accuracy is achieved. It is possible to read.

Further, in the present invention, since the entire scanning is performed in the main scanning direction, it is not necessary to switch and control the scanning of the excitation beam light performed using the polygon mirror or the galvano mirror for each scanning line, and stable scanning can be obtained and the apparatus Can be simplified.

The present invention has the above effects and is industrially very useful.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a reading area of the present invention, and FIGS. 2 and 3 are schematic diagrams for explaining a radiation image reading method based on an embodiment of the present invention. 11 …… Radiation image conversion panel 12,13,14 …… Specified area 15 …… Optical scanning line 21 …… Radiographing device 22 …… Radiation source 24 …… Frame 25 …… Radiation image reader 26 …… Controller 27 …… Keyboard 3A …… Shooting unit 303 …… Radiation image conversion panel 3B …… Reading unit 304 …… Stimulated excitation light source 305 …… Stimulated excitation light beam 308 …… Optical deflector 311 …… Sub scanning mechanism 314 …… Analog / Digital converter 315 …… Reading area control unit 316 …… Keyboard

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-55-67873 (JP, A)

Claims (6)

[Claims] 1. A radiation image conversion panel provided with a stimulable phosphor layer is irradiated with radiation to accumulate and record radiation image information, and then the radiation image conversion panel is excited by a beam of excitation light in a main scanning direction and a sub-scanning direction. In the radiation image reading method of converting the radiation image information into stimulated emission light by scanning in, and photoelectrically reading the stimulated emission light with a photodetector to obtain a radiation image, prepared regardless of the object size. A predetermined size of the radiation image conversion panel; according to the size of the subject, a radiation irradiation region for irradiating the radiation or a read designation region for reading the stored and recorded radiation image information is set, and After setting the other area according to the setting, the radiation image information is accumulated and recorded by irradiating the radiation only on the radiation irradiation area, and the excitation beam light is generated. In the main scanning direction, the entire surface of the radiation image conversion panel is scanned, and in the sub-scanning direction, scanning is performed so that the scanning density outside the reading designated area becomes smaller than the scanning density of the reading designated area. A radiation image reading method, wherein a radiation image is obtained by selecting only a signal corresponding to the designated reading area from the signals output from the photodetector by the scanning to obtain a radiation image signal. 2. The radiation image reading method according to claim 1, wherein the excitation light beam scans in the sub-scanning direction so that the scanning density outside the designated reading region becomes zero. . 3. The radiation irradiation region or the read designation region is set by selecting one of a plurality of preset regions on the radiation image conversion panel. The radiation image reading method according to claim 1 or 2. 4. A radiation image conversion panel having a stimulable phosphor layer for storing and recording radiation image information obtained by irradiating a subject with radiation, and the radiation of a predetermined size prepared regardless of the size of the subject. Input means for setting and inputting, to the image conversion panel, either a radiation irradiation area for irradiating the radiation or a reading designated area for reading the stored and recorded radiation image information according to the subject size; Means for setting the other area according to the area set by the means, a radiation source controlled to irradiate the radiation only on the radiation irradiation area, and a main scanning direction and a sub scanning direction of the radiation image conversion panel Excitation beam light scanning means for scanning the excitation beam light on the entire surface of the radiation image conversion panel in the main scanning direction. A scanning control unit that controls the excitation beam light scanning unit so that the scanning is performed so that the scanning density in the sub-scanning direction is smaller than the scanning density in the reading designated region with respect to the scanning density in the reading designated region. A photodetector that photoelectrically converts the stimulated emission light generated by scanning the excitation beam light into an electric signal; and a signal output from the photodetector, which corresponds to the designated reading area. A radiation image reading apparatus comprising: a processing unit that selects and extracts only a signal. 5. The scanning density of the excitation beam light outside the designated reading region in the sub-scanning direction is set to 0,
The radiation image reading apparatus according to claim 4, wherein the scanning control unit controls the excitation beam light scanning unit. 6. The radiation irradiation area or the reading designation area is set and input by selecting one of a plurality of areas preset on the radiation image conversion panel by the input means. The radiation image reading apparatus according to claim 4 or 5, wherein: