JPS61245100A - Radiation picture conversion panel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a radiation image conversion panel using a stimulable phosphor, and more particularly to a radiation image conversion panel that provides a highly sharp radiation image.

[Prior art] Radiographic images such as X-ray images are often used for disease diagnosis.In order to obtain this X#! However, in recent years, so-called radiography has been used in which visible light is generated and developed by irradiating this visible light onto a film using silver salt in the same way as when taking ordinary photographs. A method has been devised to extract images directly from the phosphor layer without using a salt-coated film.This method involves making the phosphor absorb the radiation that has passed through the object, and then converting the phosphor into, for example, There is a method in which the phosphor is excited by light or thermal energy to emit the radiation energy accumulated through the absorption as fluorescence, and this fluorescence is detected and imaged.Specifically, for example, as disclosed in U.S. Pat. , No. 859, 527 and JP-A No. 5
No. 5-12144 discloses a radiation image conversion method using a stimulable phosphor and using visible light or infrared rays as stimulable excitation light. This method uses a radiation image conversion panel in which a stimulable phosphor layer is formed on a support, and radiation that has passed through the object is applied to the stimulable phosphor layer of this radiation image conversion panel to visualize various parts of the object. A latent image is formed by accumulating radiation energy corresponding to the radiation transmittance, and then this stimulable phosphor layer is scanned with stimulable excitation light to radiate the accumulated radiation energy in each part. An image is obtained by converting the light into light and using an optical signal based on the intensity of this light. This final image may be reproduced as a hard copy or on a CRT. Now, the radiation image conversion panel having a stimulable phosphor layer used in this radiation image conversion method has a radiation absorption rate and a light conversion rate (including both In addition to high image granularity (hereinafter referred to as "radiation sensitivity"), it is also required that images have high sharpness. However, in general, radiation image conversion systems that have a stimulable phosphor layer The panel is created by coating and drying a dispersion containing a particulate stimulable phosphor with a particle size of about 1 to 30 μm and an organic binder on a support or a protective layer, so the stimulable phosphor The filling density of the body is low (50% filling rate), and the radiation sensitivity is sufficiently high (
In order to achieve this, it was necessary to increase the thickness of the stimulable phosphor layer as shown in FIG. 5(a). As is clear from the figure, the layer thickness of the stimulable phosphor layer is 200 μm.
-, the sensitivity of the stimulable phosphor is 50 mg/c2, and the radiation sensitivity increases linearly up to a layer thickness of 350 .mu.m, and is saturated at 450 .mu.m or more. Note that the radiation sensitivity becomes saturated because if the stimulable phosphor layer becomes too thick, scattering of the stimulable phosphor layer between the stimulable phosphor particles causes radiation inside the stimulable phosphor layer to become saturated. This is because the stimulated luminescence will not come out. On the other hand, as shown in FIG. 5(b), the image sharpness in the radiation image conversion method tends to be higher as the thickness of the stimulable phosphor layer of the radiation image conversion panel becomes thinner. In order to improve the performance, it was necessary to make the stimulable phosphor layer thinner. In addition, the graininess of images in the radiation image conversion method is determined by local fluctuations in the number of radiation quanta (quantum mottles) or structural disturbances in the stimulable phosphor layer of the radiation image conversion panel (structural mottles). When the thickness of the stimulable phosphor layer becomes thinner, the number of radiation quanta absorbed by the stimulable phosphor layer decreases, resulting in an increase in quantum mottles, or structural disorder becomes apparent, resulting in an increase in structural mottles. This causes a decrease in image quality. Therefore, in order to improve the graininess of images, the stimulable phosphor layer needs to be thick. That is, as mentioned above, in the conventional radiation 11Al image conversion panel, the sensitivity to radiation, the graininess of the image, and the sharpness of the image exhibit completely opposite trends with respect to the layer thickness of the stimulable phosphor layer. , the radiation image conversion panel could be made with some sacrifice in sensitivity to radiation, graininess, and sharpness. By the way, it is well known that the sharpness of images in conventional radiography is determined by the spread of instantaneous light emission (light emission during radiation irradiation) of the phosphor in the fluorescent screen. Image sharpness in radiation image conversion methods using stimulable phosphors is not determined by the spread of stimulated luminescence of the stimulable phosphors in the radiation image conversion panel (i.e., as in radiography). It is determined not by the spread of the emission of the phosphor, but by the spread of the stimulated excitation light within the panel. Since the accumulated radiographic image information is retrieved in a time-series manner, it is desirable that all the stimulated luminescence due to the stimulated excitation light irradiated at a certain time (ti) be collected and the stimulated luminescence caused by the stimulated excitation light irradiated at that time. However, if the stimulable excitation light spreads within the panel due to irradiation and the stimulable fluorescence existing outside the irradiated pixel (xiwF) This is because if the body is also excited, the output from the pixel (xi*yi) will be recorded from a wider area than that pixel.Therefore, for a certain time (t
If the stimulated luminescence caused by the stimulated excitation light irradiated at time (i) is only the light emission from the pixel (xLyi) on the panel that was truly irradiated with the stimulated excitation light at that time (ti), then No matter how wide the emission is, it does not affect the sharpness of the image obtained. Under these circumstances, several methods for improving the sharpness of radiographic images have been devised and still remain. For example, JP-A-55-14
Method of incorporating white powder into the stimulable phosphor layer of a radiation image conversion panel described in No. 6447, JP-A-55-1635
A method of coloring the radiation image conversion panel described in No. 00 so that the average reflectance of the stimulable phosphor in the stimulated excitation wavelength region is smaller than the average reflectance of the stimulable phosphor in the stimulated emission wavelength region. etc. However, in these methods, improving sharpness inevitably leads to a drastic decrease in sensitivity, and therefore cannot be said to be a preferable method. On the other hand, the present applicant has already applied for patent application No. 59-19636.
As a new radiation image conversion panel that improves the conventional drawbacks of the radiation image conversion panel using a stimulable phosphor as described above in No. 5, a radiation image conversion panel in which the stimulable phosphor layer does not contain a binder is provided. We are proposing a panel. 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 is significantly improved, and the transparency of the stimulable phosphor layer is improved. So,
The sensitivity of the image converting panel to the radiation #1 and the graininess of the image are improved, and at the same time, the sharpness of the image is also improved. However, in the radiation image conversion method, the sensitivity,
The demand for image quality with excellent sharpness without impairing graininess is becoming ever more stringent. [Object of the invention 1] The present invention relates to the above-mentioned proposed radiation image conversion panel using a stimulable phosphor, and further improves the same.
An object of the present invention is to provide a radiation image conversion panel that has improved sensitivity to radiation and provides images with high sharpness. Another object of the present invention is to provide a radiation image conversion panel that has improved graininess and provides images with high sharpness. [Structure of the Invention] The above-mentioned object of the present invention is achieved by a radioactive image conversion panel characterized in that it has at least one columnar block layer of stimulable phosphor on top of at least one fine particle layer of the support 1. . Next, the present invention will be specifically explained. FIG. 1 is a sectional view in the thickness direction of a radiation image conversion panel (hereinafter sometimes simply abbreviated as panel when the meaning is clear) of the present invention. In the figure, numeral 10 indicates the form of the panel of the present invention. 12ij is each fine columnar block of stimulable phosphor extending in the vertical direction (thickness direction) from the support surface, (
12ij) is a gap in the form of a 12ij open crack, groove, or depression. The stimulable phosphor layer 1 having a fine columnar block structure according to the present invention is formed by the above 12ij and (12ij). The average diameter of the fine columnar blocks 12ij is 1 to 400 μ-
is preferable, and the gap (12ij>) may be any distance as long as the fine columnar blocks 12ij are optically independent of each other, but on average it is preferably θ to 20μ.
2 is a support, 3 is a protective layer that is preferably provided, 4
is an adhesive layer that improves the adhesion between the stimulable phosphor layer and the support, which may be provided as necessary. 11 is a thickness of 172 or less of the total film thickness, preferably 1710 or less. It is a layer consisting of particles of a certain thickness, and it is sufficient that the particles are spread in at least one layer.The average particle size of these particles is 50 μm or less,
Preferably it is 15 μm or less. This layer 11 can be obtained by a vapor deposition method such as vacuum evaporation or sputtering. Materials forming these particles include various metals, ZnO1
Ti02, ^Q20. metal oxides such as, metal sulfides such as ZnS, crystalline Si1 amorphous silicon,
In addition to compounds such as SiC and 5iNSSiOz, alkali halide crystals and stimulable phosphors described below can be used. Among these, alkali halide crystals are particularly preferred in order to obtain the fine columnar block structure 12ij of the stimulable phosphor on the particles. A layer 11 as shown in FIG. 2 can be obtained, for example, by depositing alkali halide crystals or the like in a vacuum of about 10-' Torr. After obtaining this layer 11, fine columnar blocks 12ij of stimulable phosphor can be grown on the particles by pneumatic deposition. (Layer 11 also has the effect of increasing the adhesion between 12ij and the support.) The fine columnar blocks obtained in this way have the following characteristics:
The resulting columnar blocks have a finer diameter than those obtained by the method described in Nos. 266911 to 266911. To stack a plurality of layers of the above structure on a support, the above layer structure operation can be repeated as many times as necessary. When photostimulable excitation light is incident on the above-mentioned photostimulable phosphor layer having an optically independent fine columnar block structure, the excitation light is repeatedly reflected on the inner surface of the columnar block due to the light guiding effect of the fine columnar block structure and forms a columnar structure. It reaches the bottom of the columnar block without dissipating outside the block. Therefore, the sharpness of images produced by stimulated luminescence can be significantly increased. In addition to the adhesive layer, a reflective layer or an absorbing layer for stimulated excitation light and/or stimulated luminescence may be applied to the surface of the support. The thickness of the stimulable phosphor layer 1 of the panel of the present invention varies depending on the sensitivity of the panel to radiation, the type of stimulable phosphor, etc., but is preferably in the range of 10 to 800 μl,
More preferably, the amount is in the range of 0 to 500 μl. For forming the stimulable phosphor layer having a fine columnar block structure, a support having a homogeneous and smooth surface and a substrate suitable for adhering or depositing the stimulable phosphor to form a columnar block structure are used. Patterned supports can also be used. In the radiation image conversion panel of the present invention, the stimulable phosphor refers to the stimulable phosphor that is stimulated by optical, thermal, mechanical, optical, or electrical stimulation (stimulated excitation) after being irradiated with the first light or high-energy radiation. ) refers to a phosphor that exhibits stimulated luminescence corresponding to the irradiation amount of initial light or high-energy radiation, but from a practical standpoint, it is preferably a phosphor that exhibits stimulated luminescence by stimulated excitation light of 500n+* or more. It is the body. Examples of the stimulable phosphor used in the radiation image conversion panel of the present invention include Ba5Q and :Ax described in JP-A-48-80487 (where A is at least one of Dy5Tb and Tll, (o, ooi≦x<1 mol%), JP-A-48-804
M described in No. 88. A phosphor represented by S O4:A 5rSQ, :Ax (where A is at least one of Dy*Tb and Tm, and X is o, ooi≦1 mol%
be. ) phosphor, JP-A-51-298
Phosphors in which at least one of Mn, Dy and Tb is added to Na2S On-Ca504 and BaS O4 etc. described in No. 89; BeO, LiF MgS O described in JP-A-52-30487; , and C
Phosphors such as aFz, L + x B 40 t described in JP-A-53-39277: Phosphors such as CutAg, L i20 ・(B 202) described in JP-A-54-47883 X: Cu (however, X is 2<
xS3), and L i20 ・(B to 2)X:C
Phosphors such as utA g (where X is 2<xS3), SrS:Ce described in U.S. Pat. No. 3,859,527
, Sm, SrS; Eu, Sm, L a 202S: Eu
, Sm and (Zn, Cd) S :Mn, X (where X is a halogen). In addition, ZnS:Cu described in JP-A-55-12142,
Pb phosphor, general formula is B ao ・XA 1203:E
Barium aluminate phosphor represented by Ll (0.8≦X≦10), and the general formula M"0-xS io
2: A (However, L MxxMgtCa, Sr, Zn, C
d or Ba, and A is Ce, T b, Eu. Examples include alkaline earth metal silicate-based phosphors represented by Tm, Pb=TI, Ba, and (at least one of /Mn, where X is 0.5≦X≦2.5). . Also, the general formula is (Ba Mg Ca) FX: eEu”
1-yxy (where X is at least one of Br and CI,
x, y and e are respectively 0<x+y≦0.6, xy≠0
and 10-6≦e≦5X10-2. ) can be mentioned. Also, the general formula is L no X :xA (Ln is at least one of La, Y, Gd and Lu,
b, and X represents a number satisfying 0<x<0.1. ), the general formula described in JP-A-55-12145 is (B a+ -xM ''x)F X :yA (where MX
is at least one of Mg*Ca, Sr, Zn, and Cd, and X is at least one of CI, Br, and 1/I.
One, A is Eu, TbtcetTm, DytPrtHo
A phosphor represented by at least one of tNd, Yb and Er, where X and y are numbers satisfying the conditions 0≦X≦0.6 and 0≦y≦0.2, JP-A Showa 55-84
The general formula described in No. 389 is B aF X :x
CetyA (where X is one of CI, Br and I, A is In, T I, Gd, S pupil and Z
at least one of r, and X and 1y are respectively 0<x≦2X10-' and o<y≦5xio-''), described in JP-A-55-160078 The general formula is MlFX, xA:yLn (where Ml is M gt Cal B ay S rt
At least one of Zn and Cd, A is BeO,
MgOvcaO*SrO, BaO, ZnO, At20i
,Y,O,,La20i. I n20*vs 1o2t'r iOz, Zr0z,
GeO2,5nOz-N b20 s-T a20 s
and The2, Ln is Eu, T
btcetTmtDyvPrtHotNdtYb, Er
, Sm and Gd, and X is C
is at least one of I, Br and ■, and X and y are 5X10-'≦X≦0.5 and o<y≦0, respectively
．． This is a number that satisfies the condition of 2. ) Rare earth element-activated divalent metal fluorohalide phosphor, whose general formula is Zn
S:A, (Zn, Cd)S:A, CdS:A, ZnS:
A, X and CdS: A, ), general formula (1) or (II) described in JP-A-57-148285, general formula (1) XM 3 (PO4) 2 ・N
2:yAR formula (II) Ms(PO4)2
” yA (where M and N are each M gv Ca
@S r+ B At least one of alZn and Cd, X is F, CI. At least one of Br, and (/I, A is E uv
Tb. CetTmtDytPr*HotNdtErtSbtT
Represents at least one of LMn and Sn. Also, X
and y is a number that satisfies the condition 0<x≦6.0≦y≦1. ), a phosphor represented by the general formula CI[[] or (I
V) General formula (I[[] n'ReX 3 ・mA
X' z: xE u general formula (N) nReX3
・mAX' t:xEuvysm (in the formula, Re is La=
At least one of Gd, Y, and Lu; A represents an alkaline earth metal; and at least one of Ba, Sr, and Ca; X and X' represent at least one of FtCltBr. Moreover, X and y are 1XIO-'<x<3Xl0
− ', I Xl0- '<y< I Xl0-'
It is a number that satisfies the condition that n7m is I x 10-'
The condition <n/va<7×10-' is satisfied. ), and the general formula % formula %: (where Ml is at least one kind of alkali metal selected from LitNatK, Rh, and Cs, and Ml is Be, Mg, Ca, SrwBawZn, Cd, Cu, and At least one divalent metal selected from Ni.M
l is Sc, Y, La, Ce, Pr, Nd, P@, S+
*, Eu, Gd, Tb. It is at least one trivalent metal selected from Dy*HotEr+TmtYbtLutAItGat and In. , X. X'' and X'' are at least one type of halogen selected from F, CI, Br and I. A is Eu, Tb, Ce. TmtDytPrtHotNdtYb+ErtGdtL
utSmtYtT lyN a, A gvc u and M
At least one metal selected from g. Also, a is a numerical value in the range of O≦a<0.5, and b is a value in the range of O≦b
C is a numerical value in the range <0.5, and C is a numerical value in the range 0<c≦0.2. ) and the like can be mentioned. In particular, alkaline pallite phosphors are preferred because they facilitate the formation of a stimulable phosphor layer by methods such as vacuum evaporation and sputtering. However, the stimulable phosphor used in the radiation image conversion panel of the present invention is not limited to the above-mentioned phosphor,
Any phosphor may be used as long as it exhibits stimulated luminescence when irradiated with radiation and then irradiated with stimulated excitation light. The radiation image conversion panel of the present invention may be a stimulable phosphor layer group consisting of one or more stimulable phosphor layers containing at least one kind of the above-mentioned stimulable phosphors. Furthermore, the stimulable phosphors contained in each stimulable phosphor layer may be the same or different. In the radiation image conversion panel of the present invention, various polymeric materials, glass, metals, etc. are used as the support. In particular, materials that can be handled and processed into visible sheets or webs as information recording materials are suitable, and from this point of view, for example, cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, triacetate film, polycarbonate film, etc. Preferred are plastic films such as films, metal sheets of aluminum, iron, copper, chromium, etc., or metal sheets having a coating layer of the metal oxide. The layer thickness of these supports varies depending on the material of the support used, but is generally 80 μl to 1000 μl, and more preferably 80 μl to 5 μl from the viewpoint of handling.
00 μm. In the radiation image conversion panel of the present invention, a protective layer for physically or chemically protecting the stimulable phosphor layer group is generally provided on the surface where the stimulable phosphor layer is exposed. is preferred. This protective layer may be formed by directly applying a protective layer coating liquid onto the stimulable phosphor layer, or by adhering a separately formed protective layer onto the stimulable phosphor layer. good. The material for the protective layer is cellulose acetate. Common protective layer materials such as nitrocellulose, polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyester, polyethylene terephthalate, polyethylene, vinylidene chloride, and nylon are frowned upon. In addition, this protective layer can be formed using vacuum evaporation method, sputtering method, etc.
, S 1C-Sio 2-8 iN-A I20
It may also be formed by laminating different inorganic materials. Next, the vapor phase deposition method of the stimulable phosphor layer will be explained. A vacuum evaporation method is a method for tIIil. In this method, the support is first placed in a vapor deposition apparatus, and then the inside of the apparatus is evacuated to a degree of vacuum of about 10-' Torr. Next, after cleaning the surface of the support by heating it to 300 to 500°C with a heater for heating the support, the temperature of the support was set at 100°C, argon gas was introduced, and the temperature was increased to 4X10-'Torr.
The degree of vacuum should be approximately Next, electricity is applied to the boat or crucible to evaporate the alkali halide, such as rubidium bromide, in the boat or crucible by a resistance heating method. When a layer of rubidium bromide crystal particles is deposited as shown in Figure 2, the deposition is stopped. At this time, an electron beam method may be used instead of resistance heating. After setting the degree of vacuum to about 5 x 10-' Torr and the temperature of the support to 100°C, rubyridium bromide phosphor with thallium as an activator is applied to a film thickness of about 250 μm. Deposit up to As a result, a stimulable phosphor having a fine columnar block structure is deposited on the crystal grains shown in FIG. As a result, a stimulable phosphor layer containing no binder is formed, but in the vapor deposition step, it is also possible to co-evaporate using a plurality of resistance heaters or an electron beam. After the vapor deposition is completed, a protective layer is preferably provided on the side of the stimulable phosphor layer opposite to the support, if necessary, to produce the radiation image conversion panel of the present invention. Note that a step may be taken in which the support is provided after forming the stimulable phosphor layer on the protective layer. In addition, in the vacuum evaporation method, the stimulable phosphor raw material is codeposited using a plurality of resistance heaters or an electron beam, and the desired stimulable phosphor is synthesized on the support while the stimulable phosphor is simultaneously evaporated. It is also possible to form a phosphor layer. Furthermore, in the vacuum evaporation method, the object to be evaporated (support or protective layer) may be cooled or heated as necessary during evaporation, or the stimulable phosphor layer may be heat-treated after evaporation. good. A second method is a sputtering method. In this method, like the vapor deposition method, after the support is placed in a sputtering device, the inside of the device is once evacuated to a vacuum level of about 10-' Torr, and then a non-containing gas such as Ar or Ne is used as a sputtering gas. Introducing active gas into the sputtering equipment to 10-3T orr
The gas pressure should be approximately Next, in order to obtain the layer 11 shown in FIG. 1, sputtering is performed using, for example, a tarded alkali halide crystal Rbl, and the sputtering is stopped when the sputtering is completed as shown in FIG. Then, on this layer 11, for example, a stimulable phosphor having a fine columnar Glock structure is deposited to a desired thickness by battering rubidium bromide with thallium as an activator. In the sputtering process, it is possible to form the stimulable phosphor layer in multiple steps as in the vacuum evaporation method, or it is possible to form the stimulable phosphor layer in multiple steps at the same time by using multiple targets each made of a different stimulable phosphor. Alternatively, it is also possible to form a stimulable phosphor layer by sequentially sputtering the tarded materials. After the sputtering is completed, a protective layer is preferably provided on the opposite side of the stimulable phosphor layer from the support side, if necessary, similarly to the vacuum evaporation method, and the radiation image conversion panel of the present invention is manufactured. Note that a step may be taken in which the support is provided after forming the stimulable phosphor layer on the protective layer. In the sputtering method, a plurality of stimulable phosphor raw materials are targeted and sputtered simultaneously or sequentially to synthesize the desired stimulable phosphor on a support and simultaneously form a stimulable phosphor layer. It is also possible to form In addition, in the sputtering method, 0x
Reactive sputtering may be performed by introducing a gas such as =Hz. Furthermore, in the sputtering method, the object to be deposited (support or protective layer) may be cooled or heated as necessary during sputtering. Further, the stimulable phosphor layer may be heat-treated after sputtering. Another method is the CVD method. This method involves decomposing a target photostimulable phosphor or an organometallic compound containing a photostimulable phosphor raw material with energy such as heat or high-frequency power, thereby producing a photostimulable material on a support that does not contain a binder. Obtain a fluorescent phosphor layer. Alternatively, after obtaining the layer 11 by sputtering or CVD, a stimulable phosphor having a fine columnar block structure may be deposited to a desired thickness by vacuum evaporation. In this case, layer 11
This method has the advantage that a thin and uniform stimulable phosphor can be obtained, and that the stimulable phosphor having a fine columnar block structure can be deposited quickly. FIG. 3(a) shows the thickness of the stimulable phosphor layer of the radiation image conversion panel of the present invention obtained by the vapor deposition method and the relationship between the deposition amount of the stimulable phosphor corresponding to the layer thickness and the radiation sensitivity. This represents an example. Since the stimulable phosphor layer produced by the vapor deposition method according to the present invention does not contain a binder, the adhesion resistance (filling rate) of the stimulable phosphor is lower than that of the conventional stimulable phosphor coated layer. The thickness of the stimulable phosphor layer is approximately twice that of the stimulable phosphor layer, and the radiation absorption rate per unit thickness of the stimulable phosphor layer is improved, resulting in not only high sensitivity to radiation but also improved image graininess. Furthermore, the stimulable phosphor layer produced by the vapor-phase deposition method has excellent transparency, and has high transmittance to stimulated excitation light and stimulated luminescence, making the layer thickness of the stimulable phosphor layer formed by the conventional coating method much lower. It can be made thicker and more sensitive to radiation. An example of the sharpness of the panel of the present invention having a stimulable phosphor layer with a fine columnar block structure obtained as described above is shown in the third example.
It is shown at 31 in Figure (b). The panel of the present invention is disclosed in Japanese Patent Application No. 59-266912-266.
The structure is finer than the fine columnar block structure described in No. 916, and due to the light induction effect, the stimulated excitation light is repeatedly reflected on the inner surface of the columnar block and is less likely to be dissipated outside the columnar block. , patent application 1982-
As is clear from the comparison with 32 in Fig. 3(b), which shows the characteristics of the tile-like structure inherited from No. 266914, the sharpness of the image improves and the layer thickness of the stimulable phosphor increases. It is possible to further improve sharpness. Further, the characteristics of a conventional panel obtained by dispersing and coating photostimulable phosphor particles in a binder are shown in 33 in FIG. 3, and it can be seen that the image sharpness is clearly superior to this. The radiographic image conversion panel of the present invention provides excellent sharpness, granularity and sensitivity when used in the radiographic image conversion method shown schematically 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 radiation image conversion panel of the present invention.
4'6 is a photoelectric conversion device for detecting stimulated luminescence emitted from the radiation image conversion panel; 4'6 is a device for reproducing the signal detected by 45 as an image; 47 is a device for displaying the reproduced image; and 48 is a luminescent device. It is a filter that separates stimulated excitation light and stimulated luminescence and allows only stimulated luminescence to pass through. It should be noted that the elements after 45 may be of any type as long as they can reproduce the optical information from 43 as an image in some form, and are not limited to the above. As shown in FIG. 4, radiation from a radiation generating device 41 enters a radiation image conversion panel 43 of the present invention through a subject 42. This incident radiation is absorbed by the stimulable phosphor layer of the radiation image conversion panel 43, and its energy is accumulated to form an accumulated radiation transmission image. Next, this accumulated image is excited with lII exhaustion excitation light from the exhaustion excitation light source 44 to 11! ! It is emitted as exhaustion. In the radiation image conversion panel 43 of the present invention, since the stimulable phosphor layer has a fine columnar block structure, the stimulable excitation light is transmitted to the stimulable phosphor during the scanning by the above-mentioned luminance and 8HJ. Diffusion within the layer is suppressed. Since the strength of the emitted stimulated luminescence is proportional to the amount of accumulated radiation energy, this optical signal is photoelectrically converted by a photoelectric conversion device 45 such as a photomultiplier tube, and an image reproduction device 46
By reproducing the image as an image and displaying it on the image display device 47, a radiographic image of the subject can be observed. [Examples] Next, the present invention will be explained by examples. Example 1 A 095 mm thick aluminum plate was placed in a vapor deposition apparatus as a support. Next, RbB is placed in an aluminum crucible using resistance heating.
The r-crystal was placed therein and set on a resistance heating electrode, and then the evaporator was evacuated to a vacuum of I x 10-'Torr. Then, the temperature was increased to 300 to 500°C using a heater for heating the support.
After cleaning the surface of the support by heating it to 100
℃ and introduce argon gas to 4×10-'To
The degree of vacuum was set to about rr. Next, the aluminum crucible is energized and heated using the resistance heating method.
bBr was evaporated to obtain a particle layer of about 10 μm. after that,
After setting the degree of vacuum to about 5X 10-'Torr and the temperature of the support to 100°C, the stimulable phosphor RbBr: 0.004TΩ was evaporated by a resistance heating method to obtain a film with a thickness of about 250μ. A radiation image conversion panel of the present invention was obtained. The thus obtained radiation image conversion panel of the present invention was subjected to a tube voltage of 80 KV and an XAI of 10 mR.
After irradiation, photostimulation is excited with semiconductor laser light (780°Cm), and the stimulated luminescence emitted from the photostimulated phosphor layer is photoelectrically converted with a photodetector (photomultiplier tube), and this signal is used for image reproduction. The image was reproduced by a device and recorded on a silver halide film. The sensitivity of the radiation image conversion panel^ to X-rays was investigated based on the signal magnitude, and the modulation transfer function (14TF) and granularity of the image were investigated using the obtained images, which are shown in Table 1. In Table 1, the sensitivity to X#X is shown as a relative value, with the radiation image conversion panel 8 of the present invention set as 100. Further, the modulation transfer function (MTF) is a value when the spatial frequency is 2 cycles/mvn. Example 2 A 0.5 mm thick aluminum plate was placed in a sputtering apparatus as a support. Next, a CsI crystal was placed in a sputtering device as a sputtering target, and then a 1×1
The vacuum was evacuated to 0-Torr. Introducing ^r as a spafter γ-s, sputtering is performed to form a Cs of approximately 10 μm.
A particle layer of I was obtained. After that, the support provided with the Cs1 particle layer was installed in the evaporator, and the degree of vacuum was increased to IX 10-'Tor.
After setting the temperature of the support to 100°C, the photostimulable phosphor RbB:0,004TQ is evaporated by a resistance heating method to form a radiation image conversion film of the present invention with a film thickness of 250μ. Panel B was evaluated in the same manner as in Example 1, and the results are also listed in Table 1. Comparative Example 1 Stimulable phosphor, RbBr: 0,004TQ 8 parts by weight, polyvinyl butyral resin 1 layer IL part and solvent (cyclohexanone) 5 parts by weight were mixed and dispersed, and applied for a stimulable phosphor layer. The liquid was adjusted. Next, this coating solution was uniformly applied onto a black polyethylene terephthalate film as a support with a thickness of 300 μl placed horizontally, and air-dried to form a stimulable phosphor layer with a thickness of 250 μl. Comparative radiation image conversion panel P obtained in this way
1. was evaluated in the same manner as in Example 1, and the results were evaluated as IIfJ1
As is clear from the table, the radiation image conversion panel A of the present invention
, B had an X-ray sensitivity about twice as high as that of the comparative radiation image conversion panel P, and also had excellent image graininess. This is because the radiation image conversion panel of the present invention does not contain a binder in the stimulable phosphor layer, and the filling rate of stimulable phosphor is higher than that of comparative panels, and the X-ray absorption rate is good. It is. Furthermore, the radiation image conversion panels A and B of the present invention are superior in sharpness to the comparative radiation image conversion panel P, although they have higher X-ray sensitivities. This is because the stimulable phosphor layer of the radiation image conversion panel of the present invention has a fine columnar block structure, so that the scattering of the semiconductor laser, which is the stimulable excitation light, in the stimulable phosphor layer is reduced. This is to do so.

【Effect of the invention】

As described above, since the stimulable phosphor layer of the present invention has a fine columnar block structure, the scattering of the stimulable excitation light in the stimulable phosphor layer is significantly reduced. In addition, according to the present invention, the decrease in image sharpness due to an increase in the thickness of the stimulable phosphor layer is small, so it is possible to improve the sharpness of the image. By doing so, it is possible to improve radiation sensitivity without reducing image sharpness. In addition, according to the present invention, the decrease in image sharpness due to an increase in the thickness of the stimulable phosphor layer is small. It is possible to improve the graininess of. Further, according to the present invention, it is possible to stably manufacture the radiation image conversion panel of the present invention at low cost. The present invention has extremely great effects and is industrially useful.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are cross-sectional views showing a part of a radiation image conversion panel as an example of the present invention. FIG. 2 is a plan view showing a part of a radiation image conversion panel as an example of the invention. be. FIG. 3(a) is a diagram showing the thickness and adhesion amount of the stimulable phosphor layer and the sensitivity to radiation in a radiation image conversion panel according to an example of the present invention, and FIG. 3(b) is a diagram showing the spatial frequency and the modulation transfer function (M It is a figure showing the relationship with TF). Fourth
The figure is a schematic diagram of a radiation image conversion device in which the panel of the present invention is used. FIG. 5(a) is a diagram showing the stimulable phosphor layer and the attached amount and sensitivity to radiation in the conventional radiation image conversion panel, and FIG. 5(b) shows the stimulable phosphor layer in the conventional radiation image conversion panel. FIG. 3 is a diagram showing the body layer thickness, adhesion amount, and modulation transfer function (MTF) at a spatial frequency of 2 cycles/I. 1... Stimulable phosphor layer 11... Particle layer 12... Fine columnar block 2... Support 3... Protective layer 4... Adhesive layer 31... Radiation image of the present invention Characteristics of conversion panel 32・
...Characteristics of radiation conversion panel with fine columnar block structure 33 ...Characteristics of conventional radiation image conversion panel 41...
- Radiation generator 42... Subject 43... Radiation image conversion panel 44... Stimulation excitation light source 45... Photoelectric conversion device 46... Image reproduction device 47... Image display device 48-...・Filter applicant: Konishi Roku Photo Industry Co., Ltd. Figure 1 Figure 3 (b) Spatial circumference 5 dermatology (1 sheet □) Figure 4 Figure 5 (b) Procedural amendment document October 14, 1985 Patent Director General of the Agency, Director General of the Ubuya Michi Department, Review 1, Indication of the incident, Patent Application No. 88326 of 1985, 2, Name of the invention, Radiation image conversion panel, Contact information, Konishiroku Photo Industry Co., Ltd. (Telephone: 0425-83-152)
1) Patent Section 4, date of amendment order 5, "Detailed Description of the Invention" and "Brief Description of Drawings" column 6 of the specification to be amended, contents of the amendment

Claims (1)

[Claims] A radiation image conversion panel comprising at least one fine particle layer on a support, and at least one columnar block layer of a stimulable phosphor on top of the fine particle layer.