JPS5824790B2 - Electron radiation image forming method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for obtaining radiographic images using highly insulating liquids that absorb radiation such as X-rays.

A conventional method for creating radiation images (hereinafter also referred to as X-ray images) using a highly insulating liquid that absorbs radiation such as X-rays (hereinafter simply referred to as X-rays) is disclosed in Japanese Patent Application Laid-Open No. 50-87793.
No., JP-A-50-125694, JP-A-50-137
No. 176 (US Pat. No. 3,873,833).

In other words, as shown in Fig. 1, a pair of electrodes 1 and 2 are arranged almost parallel to each other with a gap between them, and by absorbing X-rays, electrons with high polarity or ions of positive and negative polarity are generated. An insulating image receiving sheet 4 is placed in this X-ray absorbing liquid 3 in contact with one electrode, and while a voltage is applied between the electrodes 1 and 2, X-rays are absorbed. This is a method in which X-rays are irradiated by a source 5, and the X-rays that have passed through a subject 6 are exposed to an X-ray absorbing liquid 3. According to this method, an insulating X-ray absorbing liquid 3 is The liquid 3 is ionized, and the generated electrons and positive polarity ions or positive and negative polarity ions move toward the corresponding electrodes 1 and 2, respectively, and an electrostatic latent image is formed on the image receiving sheet 4.

The obtained electrostatic latent image is developed into a visible image by a known electrophotographic method.

In this method, the image receiving sheet 4 is operated with being immersed in the X-ray absorbing liquid 3, so the X-ray absorbing liquid 3 must have a sufficiently high resistance in order to form an electrostatic latent image and retain the latent image. In fact, in order to sufficiently retain the latent image once formed, it is necessary for the X-ray absorbing liquid 3 to have a volume resistivity of 1014 Ω or more. cannot be used.

Additionally, in order to increase sensitivity, it is desirable to use a liquid with strong X-ray absorption, but most liquids that exhibit strong X-ray absorption are unstable strong solvents and decompose with light or heat, resulting in a low resistance value. Or, when the image receiving sheet 4 was immersed in the X-ray absorbing liquid, impurities were dissolved in the X-ray absorbing liquid 3 adhering to the image receiving sheet 4, causing abnormal discharge.

In addition, in order to increase the absorption efficiency of X-rays, CB is added to the X-ray absorbing liquid.
When solids such as r 4 +CH13 are dissolved, when the image-receiving sheet 4 is taken out, the liquid adhering to the surface dries and these solids precipitate, resulting in low resistance and disturbing the electrostatic latent image.

Furthermore, since the X-ray absorbing liquid 3 may come into contact with the outside air, it may receive various types of contamination from the outside air and become unstable.

Further, since the image receiving sheet 4 is immersed in the X-ray absorbing liquid 3, impurities are mixed in therein.

Further, since the image receiving sheet 4 is in a wet state, it is necessary to dry it, and at that time, the latent image may disappear or the X-ray absorbing liquid 3 may be mixed into the developer and deteriorate the developer.

Furthermore, the amount of X-ray absorbing liquid 3 decreases when the image receiving sheet 4 is taken in and out, which increases the amount used and poses a safety problem. There is.

Therefore, the present inventor developed an X-ray image forming method using a sealed chamber.

That is, as shown in FIG. 2, the insulation of the chamber A is such that the electrode 7 and the insulating film 8 are arranged in parallel using an insulating spacer 9, and the X-ray absorbing liquid 10 is sealed in the space between them. Insulating film 11, X on the outer surface of film 8
After overlapping the back electrode 12 with high radiation transparency and irradiating X-rays from the front of the subject 13 placed on the back electrode 12 side while applying a voltage between both electrodes 7°12, the insulating film 11
This is an electron radiation image forming method characterized in that an electrostatic latent image is formed by peeling off an electrostatic latent image from a chamber A.

However, in this method, the insulating film 11 is peeled off from the chamber A to form an electrostatic latent image, so if the chamber A is used in a position other than horizontal, after the insulating film 11 is peeled off, the Due to the weight of the liquid 10, the insulating film 8 on the chamber A side deforms, as shown in FIG. It can also be destroyed.

In addition, the latent image formed on the chamber A side must be removed before the next image is formed, but for this purpose it is necessary to apply a voltage of opposite polarity, irradiate the entire surface with X-rays, or leave it for a long time. The problem is that one has to wait for the discharge to occur and the operation is troublesome.

The present invention was developed in view of the above circumstances, and it is possible to form an electrostatic latent image by using a chamber completely filled with an X-ray absorbing liquid, and it can be used in any position. An object of the present invention is to provide an electron radiation image forming method and apparatus that enable easy erasure of electro-latent images.

This will be explained in detail below using FIG. 4 and subsequent figures.

FIG. 4 shows a cross section of a chamber A used in the present invention, in which an electrode 7 and an insulating film 8 are arranged approximately parallel to each other at a constant interval using an insulating spacer 9, and an X-ray absorbing liquid 10 is placed in the gap. A trap section 16 having a variable volume is communicated with a gap inside the chamber, and the trap section 16 is also filled with the X-ray absorbing liquid 10.

Therefore, if there are air bubbles inside the chamber A, it may cause abnormal discharge, so special care must be taken to ensure that no air bubbles remain when filling the X-ray absorbing liquid 10.

The insulating film 8 should be sufficiently thin and have guaranteed mechanical strength, such as a polyester film with a thickness of 25 μm, to prevent a decrease in resolution.
Moreover, this is desirable in order to reduce damage to the chamber A.

The electrode 7 should be made of a material that will not be altered by the X-ray absorbing liquid 8, such as a carbon plate, a metal plate coated with gelatin mixed with carbon, or a metal plate covered with a thin plastic film. .

The spacer 9 is made of a plate material having high insulation properties and a uniform thickness, such as a Delrin plate having a thickness of approximately one inch.

The enclosed X-ray absorbing liquid 10 is a liquid substance that absorbs X-rays when irradiated with X-rays and emits electrons, and has a volume resistivity of about 1012Ω or more when not excited by X-rays. For example, CCl4. which is a liquid at normal temperature and normal pressure. CH2■2゜CH2BrI +
CH2Cl1 I t C2H,I , CHBr4
It is preferable to dissolve CBr, , CHI3 +Xe +Kr, etc., which have a high X-ray absorption rate, in the solvent.

When enclosing the X-ray absorbing liquid 10, sufficient care must be taken not only to prevent the presence of the above-mentioned air bubbles, but also to prevent contamination of impurities such as charged particles and conductive particles.

Forming an X-ray image using chamber A as described above is performed in the following procedure.

That is, as shown in FIG. 5, an insulating film 11 for receiving a latent image is superimposed on the outer surface of the insulating film 8 on the chamber A side, and a back electrode 12 having high X-ray transparency is pressed onto it. .

The insulating film 11 for receiving a latent image is designed to hold an electrostatic latent image, and its high insulating properties and film thickness are determined by its ease of handling and the selection of the X-ray absorbing liquid 10.
A polyester film with a thickness of 0μ is used.

Further, the back electrode 12 is required to be a conduit body that can sufficiently transmit X-rays, and for example, an Al plate or a synthetic resin plate on which Al is deposited is used.

In this way, when the insulating film 11 for latent image reception and the back electrode 12 are stacked on the chamber A, the X-ray absorbing liquid 10 in the chamber A is maintained at a constant thickness, and the Since the insulating film 8 on the chamber side does not swell or dent due to the weight of the line-absorbing liquid 10, it can be used in any direction.

In the above configuration, while applying a high voltage (■1+V2) between the electrode 7 and the back electrode 12, the subject 13 placed on the back electrode 12 side is irradiated with X-rays from the front X-ray source 14, and then When the X-ray irradiation is completed, the applied voltage Vl is lowered by switching the switch 15, and the variable volume trap section 16 is enlarged as shown in FIG.

Since the X-ray absorbing liquid 10 inside the chamber A is generally an incompressible liquid, the volume of the gap in the chamber A decreases by the increase in the volume of the trap section 16, and the insulating film 8 recesses toward the electrode 7 side, increasing the insulation. It has a sufficient gap with the film 11.

At this time, since an electrostatic latent image is formed on the surface of the insulating film 11 by peeling discharge, it can be visualized using a known electrophotographic development process, such as a powder cloud method or a development method using a high-resistance liquid developer. can.

For example, when an X-ray absorbing liquid 10 made by dissolving the same weight of CBr4 in CCl4 is sealed in a chamber A with a gap length of 1, the applied voltage is approximately 15,000 V, and the amount of X-rays projected is equal to the expected latency. It is determined depending on the intensity of the image, but
For example, for a subject 13 corresponding to the human chest, such as a 20-degree A1 floor difference, the X-ray radiation is 0.15 at a distance of 1 m from the X-ray source at a tube voltage of 75 KVP and a tube current of 50 mA at a dose rate.
It is about the extent of irradiation for seconds.

When the X-ray irradiation is finished, the applied voltage is lowered to about 5000 V to cause peeling discharge.

The time from the end of X-ray irradiation to the end of peeling may be long enough to ensure resolution, for example, if the volume resistivity of the X-ray absorbing liquid 10 is very high, such as 1015Ω-sieve, it can be carried out with sufficient margin. If it is as low as about 1012Ω-α, it must be shortened to within a few seconds.

Next, to explain that an electrostatic latent image is formed on the insulating film 11, as shown in FIG. It is absorbed by the heavy atoms in 10, and electrons are ejected from the atoms to generate positive ions, and pairs of electrons, or ion pairs of positive and negative polarities are generated by capturing the ejected electrons.

The generated ions or electrons move toward the corresponding electrodes 7 and 12 by the action of the electric field.

The moved ions or electrons are neutralized by one exchange of electrons on the electrode 7 side, as shown in FIG. 8, and are retained as an electrostatic latent image on the insulating film 8 side.

At this time, since only an extremely small gap of about 2 μm exists between the insulating films 8 and 11, no charge transfer occurs through this gap in the electric field caused by the voltage applied during X-ray irradiation.

However, when the insulating film 8 and the insulating film 11 are separated as shown in Fig. 9, the air gap length increases, which makes it possible to ionize the air, causing electrical discharge from a part that is a certain distance away from the insulation film. An electrostatic latent image is formed on the outer surface of the transparent film 8 and the surface of the insulating film 11.

Insulating film 8 is necessary for this peeling discharge to occur smoothly.
, 11 and their thicknesses, the voltage applied during peeling may be adjusted, but under the conditions described above, the most stable value is about 5.0 OOV.

Furthermore, since the gap in the chamber A used in the present invention is several inches thick, when the insulating film 8 is recessed, it comes into contact with the electrode 7, so that the electric charges remaining inside the insulating film 8 are neutralized. Ru.

Therefore, the charges that have been stabilized by attracting each other inside and outside the insulating film 8 are neutralized on the inside, and the charges on the outside can be easily removed using an AC corona discharge device 17 as shown in FIG. In addition, the electrostatic latent image on the insulating film 8 can be easily erased.

As detailed above, the electron radiation image creation method according to the present invention has the following advantages over the conventional method using an X-ray absorbing liquid.

First of all, the X-ray absorbing liquid 10 is completely sealed and never comes into contact with the outside air, so it does not receive various contamination from the outside air, and the X-ray absorbing liquid 10 is always stable. There is.

Second, since the latent image receiving insulating film 11 is not immersed in the X-ray absorbing liquid 10, the contamination of impurities, which has been a very serious problem in the conventional method, can be solved.

Thirdly, the latent image receiving insulating film 11 does not come into contact with the X-ray absorbing liquid 10, and the insulating film 11 can be separated from the chamber A at any time after X-ray irradiation. Therefore, a low-resistance X-ray absorbing liquid 10 that cannot be used in conventional methods can be used.

Fourth, since electrostatic latent image formation is completely dry,
In the conventional method, the latent image does not disappear while the X-ray absorbing liquid 10 is dried, or the X-ray absorbing liquid does not mix into the developer, causing deterioration of the developer.

Fifth, since the X-ray absorbing liquid 10, which is often a harmful substance, is sealed, the amount used can be minimized, and safety issues can also be solved.

Sixth, although it uses liquid, it can be used in extremely flexible positions.

Seventh, the electrostatic latent image on the chamber A side can be easily erased.

The materials and values used in the above explanation are merely examples of the present invention, and conventionally known X-ray absorbing materials, insulating films, etc. can be used, and the applied voltage and X-ray dose may be adjusted accordingly. , and irradiation time may vary.

Further, in order to assist or control the peeling discharge, a charge of a specific polarity may be applied in advance to the insulating film 8 on the side of the chamber A or the insulating film 11 for receiving latent images by corona discharge or the like. .

[Brief explanation of drawings]

1 to 3 are schematic diagrams showing a conventional electron radiation image forming method, and FIG. 4 is a sectional view of a chamber according to the present invention.
5 to 10 are explanatory diagrams showing the electron radiation image forming method of the present invention. 7...Electrode, 8,11...Insulating film, 9...Spacer, 10...X
Radiation absorbing liquid, 12...X-ray transparent electrode, 13.
...Object, 14...X-ray source, 16...
...Trap part, A...Chamber.

Claims (1)

[Claims] 1. The outer surface of the insulating film 8 of a chamber A in which an electrode 7 and an insulating film 8 are arranged in parallel using an insulating spacer 9, and an X-ray absorbing liquid 10 is sealed in the gap between the electrodes 7 and the insulating film 8. After overlapping an insulating film 11 and a back electrode 12 with high X-ray transparency, and irradiating X-rays from the front of the subject 13 placed on the back electrode 12 side while applying a voltage between both electrodes 7 and 12, An electron radiation image forming method characterized by sucking the X-ray absorbing liquid 10 in the chamber A, peeling off two insulating films 8 and 11, and forming an electrostatic latent image on the insulating films 11. 2 Connect the electrode 7 and the insulating film 8 with an insulating spacer 9
The X-ray absorbing liquid 10 is sealed in the gap and the volume-variable trap section 16 provided in communication with the gap. is removably provided, and the insulating film 1
1 is provided with a back electrode 12, an X-ray source 14 is provided opposite to the back electrode 12, and a power source V is further provided to apply a voltage to the back electrode 12 and the electrode 7. Image forming device.