JPS5824788B2 - Radiographic image creation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Certain types of members emit electrons when they are heated or irradiated with light after being irradiated with radiation such as X-rays (hereinafter simply referred to as X-rays).

This electron is called an exoelectron (exelectron).

The present invention relates to a novel X-ray image creation method that utilizes this phenomenon.

Conventional methods for obtaining X-ray images include exposing a widely used silver halide emulsion film to display changes in the blackening density of reduced silver particles in the silver halide emulsion, and There are xeroradiography, which utilizes linear photosensitivity, and ionography, which utilizes the ionization phenomenon of gas or insulating liquid between opposing electrodes.

However, those using silver halide emulsion films are complicated because they require chemical processing in the development and fixing steps, and have disadvantages such as long processing times and the production of waste liquids containing harmful substances.

Furthermore, silver halide emulsion films generally have a head
Although it is suitable for photographing skeletal parts, ie, hard tissues, such as the chest, hands, and feet, it is not a suitable method for photographing soft tissues such as muscles, stomach, and intestines.

On the other hand, in xeroradiography and ionography,
Since the image is obtained as an electrostatic latent image proportional to the amount of X-rays passed through the subject, it is possible to obtain an image with good discrimination of low-contrast areas such as soft tissue due to the well-known edge effect in electrophotography.

However, xeroradiography generally has poor sensitivity due to the low photon efficiency of the photoconductor, and there are problems in terms of radiation exposure.

In addition, ionography is based on the drift of ion pairs toward the electrodes, which are generated when X-rays are absorbed by gas or insulating liquid that exists between electrodes that are placed opposite each other with a gap.
The resolution may decrease due to the scattering of secondary electrons, or to maintain the airtightness of the device when using gas, or to maintain stable insulation when using an insulating liquid.
The disadvantage was that the equipment was large-scale.

The present invention has been made in view of the above circumstances, and provides a method for obtaining X-ray images with high resolution and high sensitivity, and with simple operation and equipment.

Hereinafter, the present invention will be explained in detail using the drawings.

As shown in FIG. 1, an exoelectron emitting member 3 in which an exoelectron emitting material 2 is laminated on a conductive substrate 1 and a radiation source 4
The subject 5 is placed between the two and irradiated with X-rays.

As the exoelectron emitting material 2, beryllium oxide with a trace amount of lithium or sodium added is effective.

For example, 0.1 to 5 mo1% of a lithium compound or a sodium compound is added to and mixed with a sodium oxide raw material having a purity of 99% or more.

The lithium compound or the lithium compound may be any sulfate, hydrochloride, nitrate, or the like.

Mixing may be carried out wet or dry, but wet mixing is preferable since uniform mixing is possible.

The compound thus obtained is calcined at a temperature of 1200 to 1800° C. for 1 hour or more.

At this time, air or 02 gas is flowed into the furnace to maintain an oxidizing atmosphere.

After firing, let it cool naturally and take it out.

The fired product is in the form of a white powder or a white ceramic depending on the type of compound, and the latter is pulverized into a fine powder.

The exoelectron emitting member 3 used in the present invention is prepared by coating the above-mentioned fine powder mixed with a conductive binder such as carbon paste or Alpaste on a conductive substrate 1 made of aluminum or the like.

The exoelectron emitting member 3 irradiated with X-rays is taken out in the dark, a charge injection liquid 6 is applied to the surface of the exoelectron emitting member 3 as shown in FIG. 2, and an insulating sheet for charge reception is applied. 7 are placed in close contact with each other, a conductive liquid 8 is applied thereon, and a conductive electrode 9 is placed thereon.

A conductive electrode 9 is placed between the conductive substrate 1 and the conductive electrode 9.
A voltage E of 1000 to 2000 V is applied so that the side becomes the positive electrode.

The exoelectron emitting member 3 is heated by the heating device 10 at the same time as the voltage is applied.

As the charge injection liquid 6 described above, silicone liquid or fluorocarbon oil is suitable.

The charge injection liquid 6 lowers the barrier height between the charged surface of the exoelectron-emitting material 2 and the insulating sheet 7, facilitates charge injection at low voltage, and therefore reduces the interplanar distance. This eliminates the influence and increases transfer efficiency.

Regarding the composition and action of the charge injection liquid as described above, please refer to, for example, Photographic Science and Engineering Link (Photo to Graphic
5science and engineering)
, Volume 9, No. 5 (XC+J 5th September-October issue), No. 2
pages 83-293, non-silver photographic
Process (Non-8ilver photogr-a
phic Processes, Academic Press, 1975, R.J. Cox), No. 3
It is detailed in pages 35-352 and Japanese Patent Publication No. 48-786.

Figure 5 shows 100 mR of 137C5 in Beo2Li, which is one of the exoelectron emitting substances that can be used in the present invention.
This shows an example of a glow curve when R-rays are irradiated and heated, and curves a and b+c in the figure each have a 2mo
Be of Li ion when 1% Li2SO4 is added
Content for ions is 1.1%, 3.1%, 0.05
It corresponds to %.

As you can see from this figure, the heating temperature is 300-370'C.
is appropriate.

Therefore, when heating is performed while applying a voltage as described above, exoelectrons are emitted from the X-ray irradiated portion of the exoelectron emitting material 2 and injected into the charge injection liquid 6.

Then, due to the action of the electric field, a negative electrostatic latent image is formed on the surface of the insulating sheet 7.

1 After that, stop applying the voltage and peel off the conductive electrode 9,
Evaporate the conductive liquid on the surface.

At this time, as shown in FIG. 3, positive charges remain on the insulating sheet 7, so when the insulating sheet 7 is next separated from the exoelectron emitting member 3, the insulating The negative charge pattern injected into the boundary of the electron-emitting material 2 is not disturbed.

In particular, when the charge injection liquid 6 is insulating, the lateral diffusion of charges is small.

As shown in FIG. 4, an electrostatic latent image is formed on the insulating sheet taken out in this manner in accordance with the amount of X-rays passed through.

This electrostatic latent image can be visualized by various developing methods well known in electrophotography.

According to the present invention, an X-ray image can be obtained with a structure in which an exoelectron emitting member, an insulating sheet, and a conductive electrode are simply laminated and brought into close contact without requiring expensive materials or equipment. Since the voltage is lower, the required applied voltage can be lowered, and furthermore, since the charge transport distance is short, high resolution can be expected.

[Brief explanation of drawings]

FIG. 1 is a schematic layout diagram for irradiating X-rays to an exoelectron emitting member used in the present invention, FIGS. 2 to 4 are explanatory diagrams of the method for creating an X-ray image of the present invention, and FIG. 2 is a graph showing a glow curve with respect to temperature change. DESCRIPTION OF SYMBOLS 1... Conductive substrate, 2... Exo electron emitting material, 3... Exo electron emitting member, 6...
...Liquid for charge injection, 7...Insulating sheet, 8...Conductive liquid, 9...Conductive electrode, 10...Heating Device.

Claims (1)

[Claims] 1. After irradiating an exoelectron emitting member, which is an exoelectron emitting material laminated on a conductive substrate, through the subject,
Applying a charge injection liquid to the surface of the exoelectron emitting member,
An insulating sheet is closely placed on top of the insulating sheet, a conductive liquid is applied on top of the insulating sheet, a conductive electrode is placed on top of the insulating sheet, and a voltage is applied between the conductive substrate and the conductive electrode while heating is performed. A radiation image creation method characterized by forming an electrostatic latent image on an insulating sheet.