JPS5841515B2 - Denshi Houshi Yasensha Shinhou Niyor Gazo Keisei Houhou Oyobi Sonosouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electroradiographic image forming method characterized in that images are formed by electroradiography, and improvements to the apparatus.

Conventional radiography, or X-ray photography, involves irradiating a silver halide emulsion film (hereinafter simply referred to as a silver halide film) with X-rays that have passed through the subject, thereby ring-forming the silver in the silver halide milk. The image is visualized by forming a blackening density.

However, although X-ray photography using silver halide film as described above has high X-ray sensitivity, it is generally expensive because it consumes silver, and the development process is complicated and takes a long time, and post-processing such as developer is required. However, there are also disadvantages such as the need for careful attention.

To overcome these drawbacks, various methods have been developed that use electrophotographic processes to obtain X-ray photographs without using silver salt films.

For example, xeroradiography, which utilizes the sensitivity of a photoconductor to X-rays, and ionography or electron radiography, which utilizes the ionization of air or rare gases by X-rays, are already known.

Both of these methods differ from those using conventional silver halide films because image formation is performed based on electrostatic latent images.
Due to the edge effect, which is a common feature of electrophotography,
It has the advantage of being able to obtain images with a large amount of information on soft tissues such as muscles, keys, stomach, and intestines, which have little difference in line absorption, and can also eliminate the drawbacks of the silver halide film described above.

However, the photoconductor used in the xeroradiography method is not necessarily highly sensitive to radiation, and in the ionography method and electron radiography method, the pressure inside the chamber consisting of opposing electrodes is kept low, or Since high-pressure gas must be sealed in the chamber, there are disadvantages in that it is difficult to select a material for the chamber and the structure is complicated.

In order to eliminate these drawbacks, electroradiography using radiation-absorbing liquids has recently been studied.

In other words, this method uses an insulating radiation-absorbing liquid that generates electrons and positive polar ions or positive and negative polar ions by irradiating radiation such as X-rays between a pair of electrodes arranged almost parallel to each other with a gap between them. At the same time, an insulating image receiving sheet is placed in this liquid in contact with one of the electrodes, and while applying a voltage between the two electrodes, radiation transmitted through the subject is exposed to the insulating liquid. It's a method.

The insulating radiation-absorbing liquid is ionized according to the amount of radiation exposure, and the generated electrons and positive polarity ions, or positive and negative polarity ions, move to the corresponding electrode side, forming an electrostatic latent image on the image receiving sheet. is formed.

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

This method is attracting attention as having high sensitivity and high resolution compared to conventional X-ray photography using silver halide film, xeroradiography, ionography, and electron radiography, but it also has the following advantages. It also has drawbacks.

In other words, since an electrostatic latent image is formed on the surface that is in contact with the radiation-absorbing liquid, the volume resistivity of the radiation-absorbing liquid must be sufficiently high so that the latent image is reliably formed and does not disappear in a short period of time. is necessary.

In addition, it is a liquid substance that strongly absorbs radiation, and it is difficult to obtain a substance that satisfies this condition in normal atmosphere.

In other words, in order to absorb strong radiation, for example ■.

It is necessary to select a material containing atoms with high atomic numbers such as Br, F, etc., but liquids containing these atoms are easily decomposed and generally unstable.

For this reason, the liquid is ionized and cannot maintain high resistance.

Another drawback is that the above-mentioned liquids generally have a strong tendency to hydrolyze, so even a small amount of moisture in the atmosphere can cause hydrolysis, resulting in a decrease in resistance.

Therefore, in order to employ the method described above, it is necessary to perform extremely strict moisture control and blocking of light rays, and the apparatus itself becomes complicated and expensive.

This invention was made with the purpose of eliminating the drawbacks of such electroradiography, and it enables the use of a radiation-absorbing liquid with low resistance, which could not be used in the conventional methods, in a sealed chamber, and the above-mentioned Electroradiography is used to form an electrostatic latent image in response to incident radiation on the surface of a highly insulating film that forms part of the chamber or on the surface of an insulating latent image-receiving film placed in contact with it. By providing an image forming method and an apparatus used in the method, radiographs having high sensitivity and high resolution can be obtained easily and economically.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the method and apparatus for forming an image by electroradiography according to the present invention will be described in detail as shown in the drawings.

FIG. 1 is a cross-sectional view of a chamber 1 used in the method of this invention, in which an electrode 2 with high radiation transmittance and a highly insulating film 3 with high electrical insulation and high strength are provided between each peripheral portion. A chamber 1 with a sealed structure formed between the electrode 2 and the highly insulating film 3 is filled with a radiation absorbing liquid 5. has been done.

Further, on the side surface of the spacer 4, there is provided an injection pipe 6 for filling and discharging the radiation absorbing liquid 5 into the chamber 1.
is provided, and the opening of this injection tube 6 is closed with a stopper 7.

Note that the electrode 2 with high radiation transmittance is made of, for example, a plastic substrate on which Cr is vapor-deposited, and the highly electrically insulating film 3 is made of polyester or the like with a thickness of about 50 μm, and the gap between them is approximately It is set to 1 stud degree.

Further, as the radiation absorbing liquid 5 that fills the chamber 1, for example, a liquid in which CBr4 of the same weight as CC,/4 is dissolved is used.

After removing moisture and impurities from the liquid 5, a very small amount of benzyl alcohol is added to reduce the volume resistivity to approximately 101.
2. Adjust to about O-α before use.

On the other hand, FIG. 2 shows an apparatus for obtaining a radiation image using the chamber 1, in which a subject 9 to be imaged is placed above the chamber 1, which is located below the radiation source 8. , the electrode 2 of the chamber 1 is grounded, and a corona discharger 10 is provided below the highly insulating film 3 for discharging the surface of the highly insulating film 3 in a planar manner. A high voltage power source 11 is connected to the electric appliance 10 via a switch 12 for changing polarity.

Next, a method for forming a latent image will be described. First, the surface of the highly insulating film 3 in the chamber 1 is uniformly charged with a certain polarity, for example, a positive charge, using a corona discharger 10.

Note that this charging step may be performed using another device.

Due to the above-mentioned charging, positive charges are induced on the surface of the highly insulating film 3 as shown in FIG. 3a, and an electric field is formed between it and the grounded electrode 2.

When the above charging is completed, place the subject 9 on the electrode 2 of the chamber 1.
The polarity of the high voltage power supply 11 applied to the corona discharger 10 is changed by the switch 12 so that ions with a polarity opposite to the charged polarity are generated.
The subject 9 is exposed to radiation by projecting radiation.

As a result, ionized ions are generated in the radiation-absorbing liquid 5 irradiated with radiation, and each ion moves according to the electric field.

That is, positively charged ions generated by ionization move toward the electrode 2 as shown in Figure 3, and are neutralized by the positive charges on the portion of the electrode 2 that is irradiated with radiation.

On the other hand, the negatively charged ions transferred to the crystal insulating film 3 side remain on the inner surface of the film 3 without being neutralized by the charges on the surface of the film 3 because the film 3 is highly insulating.

In addition, since the surface of the highly insulating film 3 is charged with opposite polarity at the same time as the radiation is exposed, only the surface of the film 3 in the non-irradiated area, where no positive charge exists on the inner surface, is exposed to radiation as shown in Figure 3C.
As shown in FIG. 2, an electrostatic latent image is formed on the outer surface of the film 3 due to positive charges existing on the surface of the highly insulating film 3 which has been neutralized and irradiated with radiation.

In the example, first, a potential of 400 V is applied to the corona discharger 10 to charge the highly insulating film 3, and then a reverse polarity corona discharge is performed for 0.15 seconds, and at the same time, a voltage of 50 mR (milliroentgen) is applied at a tube voltage of 75 KVp. ) was projected for 0.1 seconds, the result was approximately 100V in the areas that were most strongly exposed to the X-rays, and almost 0V in the areas that were not exposed to the X-rays.
In between, an electrostatic latent image showing a potential intermediate between the two potentials was obtained on the surface of the highly insulating film 3 of the chamber 1 depending on the exposure amount.

The electrostatic latent image obtained can be easily visualized using an electrophotographic developer and development method.

Further, it is easily possible to transfer it to a film image using conventionally known techniques.

The image obtained by the above method had a resolution of about 8 lines/tomo and a sufficient blackening density.

On the other hand, the chamber 1 after the image transfer is cleaned by appropriate means and then reused for the next latent image forming step.

As another example, a small amount of benzyl alcohol is mixed into CC4 in the chamber 1 in which the gap between the electrode 2 and the highly insulating film 3 is 2, and the volume resistivity is set to about 1012.
When the insulating liquid 5 adjusted to about Q-α was used as an angler and the tube voltage was 75 KV and X-rays were projected at 120 mR, a high-quality image similar to that of the above example was obtained.

In the above process, the second charging step is not limited to direct current, and corona discharge may be performed using alternating current biased with appropriate direct current, and the latent image potential of the portion not exposed to X-rays can be set arbitrarily. It is a choice.

The corona discharge caused by the above-mentioned alternating current makes it easy to visualize the latent image,
And it is suitable for obtaining a stable latent image.

The X-ray absorbing liquid used in this invention is CC4, which is a liquid at normal temperature and pressure.

CH2I2, CH2Br I, CH2C,ffI
, C2H3I, CHBr3, etc. can be used, and CBr4. Xe
, Kr, etc. can also be used.

Furthermore, the method of this invention is 1013. This should not only be applied when using materials with a volume resistivity below Q-α, but also remove any residual charge before repeated use of chamber 1, even when using e.g. They can be applied in exactly the same way using appropriate methods.

The elements constituting the chamber 1 and the latent image-receiving highly insulating film 3 do not need to be particularly special, and because of the role assigned to the latent image-receiving highly insulating film 3, electrical latent images can be used. Since it is necessary to maintain the temperature for a sufficiently long time, it is desirable to use polyester, vinyl chloride, polycarbonate, and other so-called electrically insulating materials.

When a liquid containing atoms of I, Br, F, etc. is used as a radiation absorbing liquid, these atoms exist in some dissociated state, so special chemical treatment is required to avoid submerging each part of the chamber 1. It is desirable to use stable materials.

The material for the highly insulating film 3 is polyester resin,
Preferred materials include fluorinated resin and epoxy resin.

Gold, platinum, chromium, carbon, etc. are easily used as the conductive material for the electrode.

As described in detail above, in the conventional electron radiography method using a liquid, a latent image is formed on the surface that comes into contact with the liquid.
It is quite difficult to obtain a radiation-absorbing liquid with a volume resistivity of 0l3α or more, and it is easily hydrolyzed by even a small amount of moisture in the atmosphere. It is extremely difficult to maintain the volume resistivity of After that, there is no risk of the latent image disappearing, and therefore, it is not necessary to use a material with a high volume resistivity such as 1.013jQ- as in the conventional case, making it easy to select the material.

In addition, since the radiation absorbing liquid is completely sealed, there is no risk of it being hydrolyzed in contact with the outside air, and there is no risk of it becoming contaminated with soluble impurities or non-soluble impurity particles due to repeated use. There is no risk that the characteristics will be affected.

This is very economical because the device itself can be simplified, and the electrostatic latent image obtained can be easily visualized and transferred using known electrophotographic development methods, so a special development device etc. is required. There is no need to manufacture it.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a cross-sectional view of a chamber used in the method of this invention, FIG. 2 is a schematic diagram of the device, and FIGS. be. 1 is a chamber, 2 is an electrode, 3 is a highly insulating film, 5 is a radiation absorbing liquid, 8 is a radiation source, 9 is a subject, and 10 is a corona discharger.

Claims (1)

[Claims] 1. A radiation-absorbing liquid having a high radiation absorption rate is placed between an electrode 2 having high radiation transparency and a highly insulating film 3 which is placed parallel to the electrode 2 with a gap therebetween. The sample 9 is placed on top of the chamber 1, and a corona discharger 10 for charging the highly insulating film 3 is provided below the chamber 1. The object 9 is charged by the electric device 10 and then charged with the opposite polarity to the above-mentioned charging, and at the same time the object 9 is exposed to radiation from the radiation source 8. The electrostatic layer 1 is formed on the highly insulating film 3 by the radiation transmitted through the object 9. An image forming method using electroradiography, characterized by forming an image. 2. The chamber 1 is filled with a radiation-absorbing liquid having a high radiation absorption rate between an electrode 2 having high radiation transparency and a highly insulating film 3 which is placed parallel to and facing the electrode 2 with a gap therebetween. A subject 9 to be formed and photographed on this chamber 1
, a radiation source 8 for irradiating the subject 9 above the chamber 1, and a corona charger 10 for charging the highly insulating film 3 below the chamber 1. Image forming device by law.