JPH06100679B2 - Radiation image conversion panel manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a radiation image conversion panel using a stimulable phosphor.

(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. The so-called radiography, in which a film using salt is irradiated and the film is developed, is used. However, in recent years, a method of directly taking out an image from the phosphor layer without using a film coated with silver salt has been devised.

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 detecting this fluorescence and imaging. Specifically, for example, U.S. Pat. No. 3,859,527 and JP-A-55-1214.
No. 4 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 that has passed 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,
An image is obtained by an optical signal depending on the intensity of this light. This final image may be played back as a hard copy or on a CRT.

Also in the radiation image conversion panel having the stimulable phosphor layer used in this radiation image conversion method, the radiation sensitivity is high and the image graininess is good as in the radiographic method using the screen described above, and the sharpness of the image is obtained. High degree is required. However, in the radiation image conversion panel and the fluorescent screen, the high radiation sensitivity of the radiation image conversion panel means that the radiation energy has a high efficiency of absorbing and accumulating so that the radiation energy can be stimulated and emitted later by the excitation light. The high radiation sensitivity of the fluorescent screen means that the efficiency of converting radiation energy into light is high.
There is a difference in the laws of nature used, such as the fact that when radiation energy is absorbed and stored, the amount that is immediately converted into light decreases. A radiation image conversion panel having a stimulable phosphor layer is prepared by applying a dispersion containing a granular stimulable phosphor having a particle size of about 1 to 30 μm and an organic binder onto a support or a protective layer and drying it. Since it is produced, the packing density of the stimulable phosphor is low (filling ratio 50%), and it was necessary to increase the layer thickness of the stimulable phosphor layer in order to sufficiently increase the radiation sensitivity.

On the other hand, the sharpness of the image in the radiation image conversion method tends to be higher as the layer thickness of the stimulable phosphor layer of the radiation image conversion panel is smaller. It was necessary to thin the luminescent phosphor layer.

Further, the graininess of the image in the radiation image conversion method is determined by the spatial fluctuation of the radiation quantum number (quantum mottle), the structural disorder of the stimulable phosphor layer of the radiation image conversion panel (structural mottle), or the like. Therefore, as the layer thickness of the stimulable phosphor layer becomes thinner, the number of radiation quantum absorbed in the stimulable phosphor layer decreases and the quantum mottle increases, or structural disorder becomes apparent and the structure mottle increases. As a result, the image quality is degraded. Therefore, in order to improve the graininess of the image, the stimulable phosphor layer needs to be thick.

That is, as described above, in the conventional radiation image conversion panel, the sensitivity to radiation and the graininess of the image, and the sharpness of the image show the opposite tendency to the layer thickness of the stimulable phosphor layer. The radiation image conversion panels have been made at the trade-off between radiation sensitivity and some degree of graininess and sharpness.

Regarding the difference between the fluorescent screen and the radiation image conversion panel described above, the sharpness of the image in the radiographic method depends on the instantaneous light emission of the phosphor in the fluorescent screen (light emission during irradiation).
It is well known that it is determined by the spread of
On the other hand, the sharpness of the image in the radiation image conversion method using the stimulable phosphor described above is not determined by the spread of the stimulated emission of the stimulable phosphor in the radiation image conversion panel, that is, the radiation Another difference is that it is not determined by the spread of the emission of the phosphor as in the photographic method, but is determined by the spread of the stimulated excitation light in the panel. This difference is that in the radiation image conversion method, since the radiation image information accumulated in the radiation image conversion panel is taken out in time series, the stimulated emission due to the stimulated excitation light irradiated at a certain time (ti) does not occur. It is recorded as the output from a certain pixel (xi, yi) on the panel which is desirably illuminated and stimulated by excitation light at that time, but if the stimulated excitation light is scattered in the panel, etc. When the stimulable phosphor existing outside the illuminated pixel (xi, yi) is also excited and the output from the pixel (xi, yi) above is output from a region wider than that pixel, It will be recorded. Therefore, the stimulated emission due to the stimulated excitation light irradiated at a certain time (ti), the panel-shaped pixel (x
The emission from i, yi) does not affect the sharpness of the obtained image regardless of the extent of the emission.

Under these circumstances, some methods have been devised to improve the sharpness of radiographic images. For example, JP-A-55-14644
No. 7, a method of mixing a white powder in the stimulable phosphor layer of the radiation image conversion panel, the radiation image conversion panel described in JP-A-55-163500, the stimulable excitation wavelength region of the stimulable phosphor And the like so that the average reflectance in the above is smaller than the average reflectance in the stimulated emission wavelength region of the stimulable phosphor. However, these methods are not preferable methods because the sensitivity inevitably decreases remarkably when the sharpness is improved.

In view of the above-mentioned drawbacks and reciprocity between properties, the present applicant discloses a radiation image conversion panel containing no binder in the stimulable phosphor layer and a method for producing the same in JP-A-59-196365. is suggesting. According to this, since the stimulable phosphor layer of the radiation image conversion panel does not contain a binder, the filling rate of the stimulable phosphor layer is significantly improved and the stimulable excitation light of the stimulable phosphor layer is also increased. Further, the directivity of stimulated emission is improved, the sensitivity of the radiation image conversion panel to radiation and the graininess of the image are improved, and at the same time, the sharpness of the image is improved.

Now, the radiation image conversion panel not containing the binder can be manufactured by various vapor phase deposition methods such as a sputtering method, a CVD method and a vapor deposition method, but the vapor deposition method is the most preferable method in consideration of the production cost and the like. Can be said.

However, when the stimulable phosphor layer is formed by a resistance heating method which is generally performed in the vapor deposition method, a plurality of substances constituting the stimulable phosphor for a certain crucible temperature have different vapor pressures, A substance having a higher vapor pressure is preferentially evaporated. Therefore, the composition of the stimulable phosphor layer formed on the support does not match the composition of the stimulable phosphor charged in the crucible, and the sensitivity to radiation of the radiation image conversion panel is reduced, which is a serious drawback. It became clear that there is.

That is, the method of vapor-depositing the stimulable phosphor brings about various advantages as described above, but when the layer of the stimulable phosphor is formed, the vaporization condition of the phosphor is neglected. Fall into a big trap.

For example, according to the research of the present inventors regarding the RbBr: Tl stimulable phosphor using Tl as an activator, the emission intensity of the phosphor is 5th.
Is Tl content as shown in FIG its composition ratio as 10 ^-2 ~10 ⁰ mol% of In the range instantaneous light emission intensity is constant and as long as common phosphor Tl content is Osamu' constant width You don't have to be very careful about it.

However, the stimulated emission that controls the death of the radiation image conversion panel according to the present invention has a peak at around 3 × 10 ^-2 mol%, and the intensity is greatly reduced before and after that.

Therefore, when vapor-depositing a stimulable phosphor by a vapor deposition method or the like, the vapor pressures of the activator and the stimulable phosphor matrix are different from each other. From the activator, if the activator concentration in the stimulable phosphor layer in the stimulable phosphor layer is different from that of the activator, the activator is deviated from the optimum concentration before or behind the phosphor matrix. The original purpose of imparting activity eventually leads to the manifestation of poisoning by activators. The vapor pressure of RbBr is 1mmHg at 777 ℃
Br exhibits 10 mmHg at 522 ° C and has a large difference in vapor pressure.

We have not paid any attention to this point, and we often look at examples of activatable stimulable phosphor layers that have poor performance despite overall optimum activator concentration.

(Object of the Invention) The present invention relates to the above-mentioned proposed method for producing a radiation image conversion panel using a stimulable phosphor, and further improves the method. The object of the present invention is to stimulate a desired composition. Another object of the present invention is to provide a method for manufacturing a radiation image conversion panel for forming a fluorescent layer.

Still another object is to provide a method for producing a radiation image conversion panel having good graininess and sharpness, which has the advantages of the vapor deposition method, and high radiation image conversion sensitivity.

(Structure of the Invention) The present invention has a stimulable phosphor layer on a support, or a protective layer on the stimulable phosphor layer, and when the radiation carrying image information is incident, In a method of manufacturing a radiation image conversion panel, which stores and records image information in a stimulable phosphor layer, and then emits stimulated emission that carries accumulated image information when stimulated excitation light is incident, in a vacuum chamber of a vapor deposition device. In addition, the material to be vapor-deposited of the support or the protective layer and the composition components of the stimulable phosphor are divided into a plurality of evaporation source bodies according to the difference in vapor pressure, and each evaporation source body separated by a shielding plate has a predetermined interval. As described above, the inside of the vacuum chamber is set to a predetermined degree of vacuum, each evaporation source body is heated to evaporate, and the evaporation rate of each evaporation source body is controlled to control the thallium on the deposition target body. Activated rubidium halide stimulable phosphor is vapor-deposited to form the stimulable phosphor layer. There method of manufacturing a radiation image conversion panel, wherein the door, to achieve the above object by this configuration.

Next, the present invention will be described in detail.

FIG. 1 (a) shows a vapor deposition apparatus 1 used for carrying out the present invention.
It is an example, and is a schematic view of an apparatus when the evaporation source body is heated by a resistance heating method. In the figure, 1 is a bell jar (vacuum chamber), 2 is a support on which a stimulable phosphor is to be deposited, 3 is a shutter for controlling the deposition thickness, and 4 and 5 are for controlling the deposition rate on the support. The film thickness detectors 6 and 7 are resistance heaters (crucibles, boats, etc.), and evaporation source bodies 6'and 7 '. Reference numeral 12 is a shield plate, which is provided as required so that only vaporized substances to be controlled are incident on the film thickness detectors 4 and 5 when controlling the vapor deposition amount. Reference numeral 13 is a main valve, 14 is an auxiliary valve, and 15 is a leak valve, which is used in conjunction with an exhaust device (not shown) for developing, maintaining and adjusting a predetermined vacuum degree in the bell jar 1. Further, FIG. 1 (a) shows an apparatus diagram in the case of two resistance heaters as an example, but a plurality of resistance heaters and film thickness detectors corresponding to the number of evaporation source bodies for each vapor pressure are provided. Co-evaporation is performed using the same, that is, vapor deposition is performed in which vaporization conditions are given to each vaporization source body and the mutual concentration of components of the vapor deposition is set to a predetermined composition concentration.

In using the vapor deposition apparatus in the present invention, first, a stimulable phosphor or a stimulable phosphor raw material as an evaporation source is charged into the resistance heaters 6 and 7. At this time, degassing treatment is preferably performed.

Next, the support body 2 is installed facing the evaporation source body. The interval is approximately 10 to 40 cm according to the average range of the evaporation source. Next, operate the main valve 13 etc. and bell jar 1
The gas inside is removed to a vacuum degree of about 10 ^-4 to 10 ^-6 Torr. Then, the evaporation source is heated and evaporated by a resistance heater,
The shutter 3 is opened to start vapor deposition. The vapor deposition is advanced while controlling the vapor deposition rate and vapor deposition thickness by the film thickness detectors 4 and 5, and when the predetermined thickness is reached, the shutter 3 is closed and the vapor deposition is stopped. The vapor deposition rate in the present invention varies depending on the type of stimulable phosphor used or the raw material of the stimulable phosphor used and the target characteristics of the deposited film, but it is 10 ² to 10 ⁷ Å / mi.
n., and more preferably 10 ³ to 10 ⁶ Å / min. 10 ²
If it is lower than Å / min., It takes too much time to produce the stimulable phosphor layer, which is not preferable, and if it is higher than 10 ⁷ Å / min., It is difficult to control the speed, which is not preferable. Further, FIG. 1 (b) shows an apparatus diagram in the case of heating the evaporation source body by the electron beam method. In this device, those corresponding to 6 and 7 in FIG. 7A are shown in FIG.
In the above, the crucibles 8 and 9 are separated from the electron beam guns 10 and 11, and the other mechanism is the same, except that the evaporation source bodies 8'and 9'are heated by using an electron beam. Is vapor-deposited as described above.

Further, in the vapor deposition method using FIG. 1 (a) or (b), the vapor deposition target (support or protective layer) may be cooled or heated during vapor deposition, if necessary.

The heating temperature depends on the material to be vapor-deposited (support) and the type of stimulable phosphor layer, but is preferably selected from the range of room temperature to 600 ° C, and is selected from the range of 50 ° C to 400 ° C. Is more preferable.

Regarding the post-deposition treatment when the object to be vapor-deposited is heated and vaporized, it may be cooled while maintaining the degree of vacuum, or N ₂ or an inert gas may be introduced as a cooling medium into the apparatus and rapidly cooled. You may.

In addition, the stimulable phosphor layer may be heat-treated after completion of vapor deposition.

In the vapor deposition step, the stimulable phosphor layer can be formed in multiple times.

After completion of the vapor deposition, the radiation image conversion panel according to the present invention is manufactured by providing a protective layer on the stimulable phosphor layer on the side opposite to the support side, if necessary. Incidentally, after forming the stimulable phosphor layer on the protective layer, a procedure of providing a support may be adopted.

In the radiation image conversion panel according to the present invention, the stimulable phosphor means a stimulus (stimulation of photo, thermal, mechanical, chemical or electrical after the first light or high energy radiation is emitted. Excitation) refers to a phosphor that exhibits stimulated emission corresponding to the amount of light or high-energy radiation irradiated at that time, but from a practical standpoint, fluorescence that exhibits stimulated emission by stimulated excitation light of 500 nm or more is preferable. It is the body. The stimulable phosphor used in the radiation image conversion panel according to the present invention,
Thallium activated rubidium halide. This stimulable phosphor is a monovalent alkali metal such as rubidium, F, C.
It contains halogen and thallium selected from l and Br.

The radiation image conversion panel according to the present invention may be a stimulable phosphor layer group composed of one or more stimulable phosphor layers containing at least one kind of the stimulable phosphor described above. The stimulable phosphor contained in each stimulable phosphor layer may be the same or different.

The layer thickness of the stimulable phosphor layer of the radiation image conversion panel according to the present invention varies depending on the radiation sensitivity of the radiation image conversion panel, the type of the stimulable phosphor, and the like, but is 10 μm to 1000 μm.
It is preferably selected from the range of m, 20 μm to 800 μm
More preferably, it is selected from the range.

FIG. 2 shows the relationship between the layer thickness of the stimulable phosphor of the radiation image conversion panel according to the present invention, the amount of the stimulable phosphor attached to the layer thickness, and the radiation sensitivity. Since the stimulable phosphor layer of the radiation image conversion panel according to the present invention does not contain a binder as in the conventional panel, the adhesion amount (filling rate) of the stimulable phosphor is the same as that of the conventional radiation image conversion panel. It is about 2 times, and the radiation absorption rate per unit thickness of the stimulable phosphor layer is improved, so that the radiation sensitivity is higher than that of the conventional radiation image conversion panel and the graininess of the image is improved.

Further, since the stimulable phosphor layer of the radiation image conversion panel according to the present invention does not contain a binder, it has excellent directivity for stimulated excitation light and stimulated emission, and the stimulated excitation light and It has high transmittance for exhaust emission, and can be thicker than the conventional radiation image conversion panel.

Furthermore, since the stimulable phosphor layer of the radiation image conversion panel according to the present invention is excellent in the directivity of stimulated excitation light and stimulated emission as described above, the stimulable phosphor layer of stimulated excitation light. The scattering in the inside is reduced, and the sharpness of the image is significantly improved.

As the support used in the radiation image conversion panel according to the present invention, various polymer materials, glass, metals and the like are used, and cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, triacetate film, polycarbonate film. A plastic film such as, a metal sheet of aluminum, iron, copper, chromium or the like, or a metal sheet having a coating layer of the metal oxide is preferable.

The surface of these supports may be a smooth surface, may be a matte surface for the purpose of improving the adhesiveness with the stimulable phosphor layer, and may be provided with a reflection layer or an absorption layer.

Further, the surface of the support is an uneven surface as shown in FIG. 3 (a).
31 or a structure in which tile-shaped plates 33 separated from each other as shown in (b) are spread. In the case of FIG. 3 (a), the stimulable phosphor layer is subdivided by the uneven surface as shown in the sectional view of FIG. 3 (c), so that the sharpness of the image is further improved. In the case of FIG. 3B, the stimulable phosphor layer is maintained while maintaining the contour of the tile plate 33 of the support, and as a result, the stimulable phosphor layer is shown in FIG. As shown in the cross-sectional view of FIG. 4), the sharpness of the image is further improved because the columnar block 35 of the stimulable phosphor is isolated by the crack 36.

Further, these supports may be provided with an undercoat layer on the surface on which the stimulable phosphor layer is provided for the purpose of improving the adhesiveness with the stimulable phosphor layer. The layer thickness of these supports varies depending on the material of the support used, etc., but is generally 80 μm to 20 μm.
00 μm, more preferably 80 μm from the viewpoint of handling
It is m to 1000 μm.

In the radiation image conversion panel according to the present invention, a protective layer for physically or chemically protecting the stimulable phosphor layer is generally provided on the surface on which the stimulable phosphor layer is exposed. May be. This protective layer may be formed by directly coating the protective layer coating solution on the stimulable phosphor layer, or by forming a protective layer separately formed in advance on the stimulable phosphor layer. Good. As the material for the protective layer, usual materials for the protective layer such as cellulose acetate, nitrocellulose, polymethylmethacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyester, polyethylene terephthalate, polyethylene, vinylidene chloride and nylon are used. Further, this protective layer may be formed by laminating inorganic substances such as Sic, SiO ₂ , SiN, Al ₂ O ₃ by a vapor deposition method, a sputtering method or the like. Generally, the thickness of these protective layers is preferably about 0.1 μm to 100 μm.

The stimulable phosphor according to the present invention may contain other metals as long as the effects of the present invention are not impaired.

The radiation image conversion panel according to the present invention provides excellent sharpness, graininess and sensitivity when used in the radiation image conversion method schematically shown in FIG. That is, in FIG. 4, 41 is a radiation generator, 42 is a subject, 43 is a radiation image conversion panel of the present invention, 44 is a stimulated excitation light source, and 45 is a stimulated fluorescence emitted from the radiation image conversion panel. Photoelectric conversion device, 46 is a device for reproducing the signal detected by 45 as an image, 47 is a device for displaying the reproduced image, 48
Is a filter that separates stimulated excitation light and stimulated fluorescence and transmits only stimulated fluorescence. It should be noted that after 45, it is not limited to the above as long as the optical information from 43 can be reproduced as an image in some form.

As shown in FIG. 4, the radiation from the radiation generator 41 passes through the subject 42 and the radiation image conversion panel 43 of the present invention.
Incident on. The incident radiation is absorbed by the stimulable phosphor layer of the radiation image conversion panel 43, the energy is accumulated, and an accumulated image of a radiation transmission image is formed. Next, this accumulated image is excited by stimulated excitation light from the stimulated excitation light source 44 and emitted as stimulated emission. Radiation image conversion panel 43
Is, because the stimulable phosphor layer does not contain a binder and the transparency of the stimulable phosphor layer is high, the stimulable excitation light is stimulable during scanning with the stimulable excitation light. Diffusion in the phosphor layer is suppressed.

Since the intensity of stimulated emission emitted is proportional to the amount of accumulated radiation energy, this optical signal is photoelectrically converted by the photoelectric conversion device 45 such as a photomultiplier tube, and reproduced as an image by the image reproduction device 46. By displaying with the image display device 47, a radiation transmission image of the subject can be observed.

(Example) Next, the present invention will be described with reference to an example.

Example 1 Quartz glass having a thickness of 1000 μm was placed in a vapor depositor as a support. Next, put RbBr, which is the raw material of the desired alkali halide stimulable phosphor (RbBr: 0.0006Tl), into the molybdenum boat for resistance heating, and put it in the other tantalum boat.
TlBr was charged and set on the resistance heating electrode, and then the vaporizer was evacuated to a vacuum degree of 2 × 10 ⁻⁶ Torr. Next, RbBr and TlBr were evaporated by a resistance heating method by passing an electric current through each boat of molybdenum and tantalum. In order to obtain the desired stimulable phosphor layer, RbBr and TlBr were measured by each film thickness detector.
The deposition rate of RbBr is controlled to 1800 Å / S and the deposition rate of TlBr is controlled to 2.4 Å / S by detecting the deposition rate of each of them and feeding back to each of the deposition rate controllers. Radiation image conversion panel A was obtained by depositing to a thickness of 300 μm by the manufacturing method of the present invention.

The thus obtained radiation image conversion panel A according to the present invention was irradiated with 10 mR of X-ray having a tube voltage of 80 KVp, and then stimulated by He-Ne laser light (633 nm) to be radiated from the stimulable phosphor layer. The stimulated emission thus generated was photoelectrically converted by a photodetector (photomultiplier tube), and this signal was reproduced as an image by an image reproducing device and recorded on a silver salt film. The sensitivity of the radiation image conversion panel A to X-rays was examined from the magnitude of the signal, and the results are shown in Table 1.

In Table 1, the sensitivity to X-rays is shown as a relative value with the radiation image conversion panel A according to the present invention as 100.

Example 2 A radiation image conversion panel B according to the present invention was obtained in the same manner as in Example 1 except that two electron beam guns were used for heating and evaporation instead of the resistance heating method as the evaporation source for heating and evaporation.

The radiation image conversion panel B according to the present invention thus obtained was evaluated in the same manner as in Example 1, and the results are also shown in Table 1.

Comparative Example 1 1000 μm thick quartz glass was placed in a vapor depositor as a support. Next, put the alkali halide stimulable phosphor (RbBr: 0.0006Tl) in the molybdenum boat for resistance heating, set it on the resistance heating electrode, and then evacuate the vaporizer to 2 × 10 5.
^-6 Torr vacuum level.

Next, a current is passed through the molybdenum boat, the alkali halide stimulable phosphor is evaporated by the resistance heating method, the deposition rate is detected by the film thickness detector, and the deposition rate is set to 1800Å / S by moving back to the deposition rate controller. While controlling so that the layer thickness is 300μ on the support.
The radiation image conversion panel P was obtained by a comparative manufacturing method by depositing to a thickness of m.

The comparative radiation image conversion panel P thus obtained was evaluated in the same manner as in Example 1, and the results are also shown in Table 1.

Comparative Example 2 A radiation image conversion panel Q according to Comparative Example 1 was prepared in the same manner as in Comparative Example 1 except that the raw material of alkali halide stimulable phosphor (a mixture of 1 mol of RbBr and 0.0006 mol of TlBr) was used as the evaporation source in Comparative Example 1. Obtained.

The comparative radiation image conversion panel Q thus obtained was evaluated in the same manner as in Example 1, and the results are also shown in Table 1.

As is clear from Table 1, the radiation image conversion panels A and B manufactured by the manufacturing method of the present invention have the same graininess and sharpness as those of the radiation image conversion panel P manufactured by the comparative manufacturing method.
The line sensitivity was about 3 times higher. This is because the vapor pressure of TlBr, which is an activator during the formation of the stimulable phosphor layer, is significantly different from the vapor pressure of RbBr, so that in the comparative example, the target concentration of the formed stimulable phosphor layer is obtained. In the example, RbBr and TlB were not doped during the deposition.
This is because the stimulable phosphor layer having the target activator concentration was obtained by controlling the vapor deposition rate of each component.

Example 3 Quartz glass having a thickness of 1000 μm was set in a vapor depositor as a support. We prepared molybdenum and tantalum boats for resistance heating. RbBr and CsF, which are the raw materials for the desired alkali halide stimulable phosphor (0.9RbBr / 0.1CsF: 0.001Tl), were molybdenum boats, and TlBr was a tantalum boat. Each of them was separately set in a resistance heating electrode, and then the vaporizer was evacuated to a vacuum degree of 2 × 10 ⁻⁶ Torr.

Next, an electric current was passed through each boat to evaporate RbBr, CsF, and TlBr by the resistance heating method. RbBr, CsF, and TlB were measured by each film thickness detector in order to obtain the target stimulable phosphor layer.
The deposition rate of RbBr is controlled to 1600Å / S and the deposition rate of CsF is set to 240Å / S TlBr to 4Å / S by detecting the deposition rate of r and moving back to each deposition rate controller. On the other hand, a radiation image conversion panel C according to the present invention was obtained by depositing on the support until the layer thickness became 300 μm.

The radiation image conversion panel C according to the present invention thus obtained was evaluated in the same manner as in Example 1 and the results are shown in Table 2. In Table 2, the sensitivity to X-rays is shown as a relative value with the radiation image conversion panel C according to the present invention as 100.

Comparative Example 3 0.9 RbBr as a stimulable phosphor deposited in Comparative Example 1
A comparative radiation image conversion panel R was obtained in the same manner as in Comparative Example 1 except that 0.1 CsF: 0.001 Tl was used.

The comparative radiation image conversion panel R thus obtained was evaluated in the same manner as in Example 1, and the results are also shown in Table 2.

As is clear from Table 2, the radiation image conversion panel C according to the present invention has an object by controlling the deposition rate of each component of RbBr, CsF and Tl of the stimulable phosphor layer formed by co-deposition. As a result of obtaining a stimulable phosphor layer having a composition and an activator concentration, as compared with the comparative panel R, granularity,
Although the sharpness was the same, the X-ray sensitivity was 2.5 times higher.

(Effects of the Invention) As described above, according to the present invention, when a desired stimulable phosphor layer is obtained by the vapor deposition method, a component having a vapor pressure different from that of the other components is included. However, since a stimulable phosphor layer having a desired composition and activator concentration can be obtained, it is possible to improve the sensitivity to radiation without lowering the graininess and sharpness.

The present invention is extremely effective and industrially useful.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an example of a vapor deposition apparatus used in the present invention. FIG. 2 shows the sensitivity characteristics of the radiation image conversion panel obtained by the present invention. 3 (a) and 3 (b) are examples of the support used in the present invention, and FIGS. 3 (c) and 3 (d) are the production method of the present invention in which a stimulable phosphor layer is provided on the support. 2 is an example of a cross-sectional view of a radiation image conversion panel according to FIG. FIG. 4 is a diagram illustrating a radiation image conversion method. FIG. 5 is a graph showing the Tl concentration dependence of the instantaneous emission and stimulated emission intensity in the stimulable phosphor (RbBr: Tl). 1 …… Bell jar 2 …… Supporter 3 …… Shutter 4,5 …… Film thickness detector 6,7 …… Resistance heater 6 ′, 7 ′, 8 ′, 9 ′ …… Evaporation source 8,9… … Crucible 10,11 …… Electron beam gun 12 …… Shield plate 13 …… Main valve 14 …… Auxiliary valve 15 …… Leak valve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Fumio Shimada No. 1 Sakura-cho, Hino-shi, Tokyo Konishi Roku Photo Industrial Co., Ltd. J. Tamura (56) Reference JP 62-75400 (JP, A) Special KOSHO 52-20818 (JP, B1)

Claims (1)

[Claims] 1. A stimulable phosphor having a stimulable phosphor layer on a support, or a protective layer on the stimulable phosphor layer, which is irradiated with radiation carrying image information. In a method of manufacturing a radiation image conversion panel that stores and records image information in a layer, and then emits stimulated luminescence carrying stored image information when stimulated excitation light is incident, the support is provided in a vacuum chamber of a vapor deposition apparatus. Alternatively, the material to be vapor-deposited in the protective layer and the composition components of the stimulable phosphor are divided into a plurality of evaporation source bodies according to the difference in vapor pressure, and the evaporation source bodies separated by a shielding plate are opposed to each other at a predetermined interval. After that, the inside of the vacuum chamber is set to a predetermined degree of vacuum, each evaporation source body is heated to evaporate, and the evaporation rate of each evaporation source body is controlled to activate the thallium-activated halogenation on the deposition target body. Characterized in that a rubidium stimulable phosphor is vapor-deposited to form the stimulable phosphor layer. Radiation image conversion panel manufacturing method.