JPS6165200A - Radiation image conversion panel and manufacture thereof - 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 Field of Application) The present invention relates to a radiation image conversion panel using a photostimulable phosphor, and more specifically to a radiation image conversion panel that provides a highly sharp radiation image. It concerns the panel.

(Prior Art) Radiographic images such as X-ray images are often used for disease diagnosis. In order to obtain this X-ray image, the X-rays that have passed through the object are irradiated onto a phosphor layer, thereby producing visible light, which is then used with silver salt in the same way as when taking ordinary photographs. A so-called radiographic photograph is used, in which a film is exposed to light and developed. However, in recent years, methods have been devised to extract images directly from the phosphor layer without using a film coated with silver salt.

In this method, the radiation transmitted through the object is absorbed by a phosphor, and then this phosphor is excited with light or thermal energy, so that the phosphor absorbs the radiation accumulated by the absorption. There is a method in which the fluorescent light is detected and imaged by emitting the fluorescent light. Specifically, for example, U.S. Pat. ing. This method uses a radiation image conversion panel in which a stimulable phosphor layer is formed on a support. A latent image is formed by accumulating radiation energy corresponding to the radiation transmittance of each part of the object, and then the accumulated radiation energy of each part is radiated by stimulating this photostimulable phosphor layer with stimulation excitation light. This is converted into light, and an image is obtained using an optical signal based on the intensity of this light. This final image may be reproduced as a hard copy or on an OR,T.

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 intensifying screen. In contrast, the image sharpness in the radiation image conversion method using the above-mentioned photostimulable phosphor is not determined by the spread of stimulated luminescence of the photostimulable phosphor in the radiation image conversion panel. , that is, it is not determined by the spread of the phosphor's emission as in radiography, but rather depends on the spread of the stimulated excitation light within the panel.

This is because in this radiation image conversion method, the radiation image information stored in the radiation image conversion panel is retrieved in a time-series manner, so that the Preferably, the light emission is recorded as the output from a certain pixel (xi, yi) on the panel that was illuminated with the photostimulation excitation light at that time. The irradiated pixel (xi) spreads within the panel due to scattering, etc.

If the photostimulable phosphor existing in jjlli outside of yi) is also excited, the output from a wider area than that pixel will be recorded as the output from the pixel (x' + y') above. It is from. Therefore, a certain time (ti
), if the stimulated luminescence due to the stimulated excitation light irradiated at that time (tl) is only the light emission from the pixel (xi, yi) on the panel that was truly irradiated with the stimulated excitation light at that time (tl), No matter how wide the light emission is, it does not affect the sharpness of the image obtained.

The radiation image conversion panel used in the above radiation image conversion method has at least a photostimulable phosphor layer made of a photostimulable phosphor. The stimulable phosphor layer is generally provided on a suitable support, but if the stimulable phosphor layer has self-shape retention, the stimulable phosphor layer itself becomes a radiation image conversion panel. obtain. Furthermore, usually on the surface of the photostimulable phosphor layer opposite to the surface where the photostimulable phosphor layer comes into contact with the support,
A protective backing layer is provided to physically or chemically protect the stimulable phosphor layer. In such a conventional radiation-1 phenomenon change panel, the mean free path of the photostimulable excitation light in the photostimulable phosphor layer becomes longer due to scattering of the photostimulable excitation light, and therefore, the photostimulable excitation light becomes longer. This method has the disadvantage that the excitation light spreads out relatively widely in the phosphor layer, resulting in a significant deterioration in sharpness, and there is a strong desire to improve this.

As a method for improving the sharpness of a radiation image conversion panel, there is a method of mixing white powder into the 16-exhaustible phosphor layer of a radiation image conversion panel similar to JP-A-55-146447;
In the radiation image conversion bath system described in JP-A-55-163500, the average reflectance of the monostimulable phosphor in the 1i4iε exhaustion wavelength region is equal to the average reflectance of the stimulable phosphor in the stimulated emission wavelength region. A method is known in which coloring is performed so that the ratio is smaller than the ratio. However, in these methods, improving sharpness inevitably leads to a significant decrease in sensitivity, and therefore cannot be said to be a preferable method.

(Object of the Invention) The present invention has been made in view of the above-mentioned drawbacks of radiation image conversion panels using photostimulable phosphors.
An object of the present invention is to provide a radiation image conversion panel that provides highly sharp radiation images without reducing sensitivity.

Another object of the present invention in addition to the above-mentioned object is to provide a method for manufacturing a conversion panel for radiation 1I that satisfies the above-mentioned object.

(Structure of the Invention) The object of the present invention is to provide a radiation surface elongation conversion panel having a 1L stimulable phosphor layer formed by dispersing a stimulable phosphor in a binder. The particles of the photostimulable phosphor are the hVJJt
A radiographic image characterized by having a distribution arrangement in terms of particle diameter f4i L in the direction perpendicular to the plane angle of the line 1l This is achieved by a manufacturing method in which a stimulable phosphor layer is formed by applying a stimulable phosphor layer.

In the present invention, the term "stimulable phosphor" refers to a stimulable phosphor that is irradiated with the first light or high-energy radiation, and is then irradiated with the first light or high-energy radiation. A phosphor that re-emits light corresponding to the amount of energy radiation irradiated. Here, light includes visible light, ultraviolet light, and infrared light among electromagnetic radiation, and high-energy radiation includes X, l, Gaff 1M, beta rays, alpha rays, neutron rays, and the like.

The present invention will be explained in detail below.

Examples of the photostimulable phosphor used in the radiation image conversion panel of the present invention include BaSO4:Ax (where A, Dy, 'r
at least one of b and Tm, and X is 0.00
A phosphor represented by 1≦x (1 molti), MgSO2: Ax (
However, A is either Ho or C Dy, and 0.0
01≦X≦1 mole), SrSO4 described in JP-A-48-8 T1489
: AX (where A is) y, Th and Tm, at least one of which is present, and X is 0.001≦x (1 mol), JP-A-51-29889
NaSO4, CaSO4 and BaS described in No.
A phosphor in which at least one of Mn, Dy, and Tb is added to O4, etc., BeO, LiF, MgSO4, and CaF described in JP-A No. 52-30487.
2nd class phosphor, L i 2B407 described in JP-A No. 53-39277: phosphor such as Cu, Ag, L+2 described in JP-A-54-47883
0・(B202) X: Cu (However, X is 2 <
x≦3), and Li2o” (B202)X:Ou
, Ag (where X is 2<x≦3), and S r described in U.S. Pat.
S: Ce + Sm + Sr S; Eu,
Sm, La2028: Eu, Sm and (Z
n, cci)s:Mn.

Examples include a phosphor represented by X (where XH halogen). Furthermore, the ZnS:Ou,Pb phosphor described in JP-A-55-12142, whose general formula is Ba0-
xAl2O3: Barium aluminate phosphor expressed by ELI (0.8≦X≦10) and whose general formula is M'O
・xsio□2A (However, M' is Mg, Sr, Zn,
cd or Ba, and A is Ce, Tb, Eu, Tm
, Pb, TA! , Bi and pigeon.
species, and X satisfies O65≦X≦2.5. ) are alkaline earth metal silicate-based phosphors. Also, the general formula is (Ba Mg Ca )FX:eEu”1-X
-/X Y (However, X is at least one of Br and C1,
x, y and e are each 0 (x + y≦06, xy
≠The general formula described in the 1985-12144 publication is T, nOX: xA (However, Ln represents at least one of La, Y, Gd and Lt+, and X represents CI and/or Br. , A is Ce and/
Cross over Tb, x? Represents a number that satisfies ir+<x<0.1. ), Special Edition 11, 1984-12
The general formula described in No. 145 is (Bax-xM'x)FX: yA (However, Ml is
A is Eu, Tb, Oe, Tm, Dy;
.

At least one of R, r, Ho, Nd, Yb and Er, X and y are O≦X≦0.6 and 0≦y≦
It represents a number that satisfies the condition of 0.2. ), the general formula described in JP-A-55-84389 is BeFX: xoe, yA (however, X ke CJ,
at least one of Br and I, A is In, Tl
, Gd, Sm and Zr, and X and y are respectively O<x≦2X]O-' and O
<y≦5X10-2. ), a phosphor represented by
What is the general formula described in JP-A-55-160078? vl'FX-xA: yLn (However, M is at least one of Mg, Oa, Sr, Zn and Cd, A is Bed, MgO, C!aO
, SrO, Bad, ZnO.

Al2O3, Y2 (J3. La2O3, In2O3,
5i02. TiO2, ZrO2゜GeO2, 5n02
, at least one of Nb2O5, Ta205 and ThO2, LnEu, Tb, Ce, Tm,
Dy, Pr.

F (at least one of o, Nd, Yb, Er, Srn and Gd, and each of X and y is 5
This is a number that satisfies the conditions of X 10-5≦X≦0.5 and o<y≦0.2. ) is a rare earth element-activated divalent metal fluorohalide fluorohalide, whose general formula is ZnS:A,
CdS: A, (Zn, Cd)8: A, Zn
S: A, X and Cd8: A, X (However, A is Ou.

Ag, Au or Mn, and X is halogen. )
A phosphor represented by the general formula (1) or (It) described in JP-A-B@57-148285, a general formula (
I: ] xM3(PO4)2 Conflict NX2: yA general formula (II: l M3(PO4)2.yA (wherein M and N are Mg, Ca, Sr, Ba, respectively).

At least one of Zn and Cd, X is Fl(J.

At least one of Br and ■, A is Eu and Tb.

Ce, Tm, Dy, Pr, Ha, Nd, Y
At least one of b, Er, Sb, Td, Mn and Sn represents a food source. Also, X and y are 0 (x≦6
, 0≦y≦1. ), and the general formula (Iff) or [1■] General formula (Iff) nReX3 ・mAX'2:
xEu general formula (IV) nReX3 ・mAX'2
: xEu, ysm (in the formula, La, Gd,
At least one of Y, Lu, A is an alkaline earth metal, at least one of Ha, Sr, Ca, X
and X' represents at least one of F, 'O1, and Br. In addition, X and y are ■×IO−”(x(3X
10', t x 1o-'< y < 1 x 10
-' is a number that satisfies the condition, n7m is ] X 1O
-3 (n/1n (satisfies the condition 7X 10-1)
A phosphor, etc., represented by is carried out. However, the phosphor used in the radiation image conversion bag of the present invention is not limited to the above-mentioned phosphor. Any phosphor may be used as long as it exhibits stimulated luminescence.

The average particle diameter of the photostimulable phosphor used is determined to be an average particle size of 01 to 10, taking into consideration the sensitivity and granularity of the radiation image conversion panel.
It is appropriately selected within the range of 0 μm.

More preferably, those having an average particle size of 0.5 to 40 μm are used.

The radiation set image conversion panel of the present invention comprises a photostimulable phosphor layer comprising one or more photostimulable phosphor layers containing at least 41 types of the above-mentioned photostimulable phosphors. It may be group i. The stimulable phosphor contained in each stimulable phosphor layer may be [01-] or may be different.

The above-mentioned photostimulable phosphor layer is prepared by dispersing the photostimulable phosphor in a suitable binder field to prepare a coating solution, and then forming a predetermined particle size distribution arrangement of the phosphor particles in the layer thickness direction. It is created by coating it to make it look like this.

Next, a method for manufacturing a panel of the present invention comprising a stimulable phosphor layer having the above particle size distribution arrangement in the layer thickness direction will be described. The first method is the sedimentation method. In this method, first, a protective layer is separately formed and divided into 7 flat layers.

Next, a stimulable phosphor dispersed in a suitable binder of selected viscosity and specific gravity is applied onto this protective layer. The stimulable phosphor layer is dried at a constant temperature for a sufficient period of time to allow the stimulable phosphor particles to settle and separate. The photostimulable phosphor particles in the photostimulable phosphor layer are separated according to Stokes' law, with large particles settling at the bottom (on the side of the separately formed protective layer). After drying, the panel of the invention is produced by gluing the support. It is also possible to apply a fluorescent dispersion onto the support and adhere the retention layer thereto.

Another method of manufacturing is to separate the photostimulable phosphor using a water sieve or other phosphor separation method to obtain a smooth particle size.
After separating into about 5 pillars and dispersing each stimulable phosphor in a suitable binder, a dispersion of particles with a predetermined particle size is selected and sized to give a predetermined distribution arrangement on a sand retaining layer. It is manufactured by repeating coating and drying in order starting with the stimulable phosphor, and bonding the support after coating and drying the final dispersion. The procedure for using the Mukaho back thigh and support body may be reversed.

Furthermore, I? in the photostimulable phosphor layer? l The size distribution of the photostimulable phosphor particles in the thickness direction increases linearly, convexly, concavely, or stepwise from the protective layer to the supporting body. A quadratic array can also be given to the distribution array.
It is also possible to use a combination of the various distribution arrangements described above. FIG. 1 shows some embodiments of the distribution arrangement of the photostimulable phosphor particle diameter in the layer thickness direction in the radiation image conversion panel of the present invention, but the present invention is not limited thereto. No 0 It should be noted that, from the viewpoint of sensitivity, it is preferable that the particle size distribution arrangement of the phosphor particles is such that large particles are arranged on the stimulated excitation light incident side.

Examples of binders used in the present invention include proteins such as gelatin, polysaccharides such as dextran, or gum arabic, polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethylcellulose, vinylidene chloride-vinyl chloride copolymer, polymethyl Binders commonly used in layer construction are used, such as methacrylates, vinyl chloride-vinyl acetate copolymers, polyurethanes, cellulose acedate butyrate, polyvinyl alcohol, and the like. Generally, the binder is used in an amount of 0.01 to 1 part by weight per part of the stimulable phosphor. Shiη・
However, from the viewpoint of sensitivity and sharpness of the obtained radiation image conversion panel, it is preferable that the amount of the binder is small, and from the viewpoint of ease of coating, it is more preferably in the range of 0.03 to 0.02 parts by weight.

Stimulable phosphor of the radiation-pure image conversion panel of the present invention! The reproduction of q-stone is based on the characteristics of the target radiation image conversion panel, the type of photostimulable phosphor, the mixing ratio of the binder and the photostimulable phosphor, etc. ((
Therefore, the thickness is preferably selected from the range of 10 μm to 1000 μm, and more preferably selected from the range of 10 μm to 500 μm.

In order to improve the sharpness of the radiation image conversion panel of the present invention, white powder is added to the stimulable phosphor IJJ of the radiation image conversion panel as disclosed in JP-A-55-146447. It is also possible to disperse the
No. 5-163500, the support or protection J@ on the bottom surface of the phosphor layer for the photostimulable phosphor layer of the radiation image conversion panel or the phosphor layer against incident stimulable excitation light is disclosed in Japanese Patent No. 5-163500.
It may also be colored with a coloring agent that absorbs the stimulated excitation light.

As the support used in the radiation image conversion panel of the present invention, various polymeric materials, glass, etc. are used.
In particular, materials that can be processed into flexible sheets or rolls are suitable for handling as information recording materials.From this point of view, examples include cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, triacetate film, Particularly preferred are psystinok films such as polycarbonate films. These supports may be provided with a subbing layer on the surface on which the stimulable phosphor layer is provided, for the purpose of improving adhesion to the stimulable phosphor layer. Further, the film thickness of these supports varies depending on the material of the support used, etc., but is generally 80 μm to 1 (100 μm), and more preferably 80 μm to 500 μm from the viewpoint of handling.

In the radiation-pure image conversion panel of the present invention, the photostimulable phosphor layer is generally physically or chemically attached to the side opposite to the side on which the support for the photostimulable phosphor layer is provided. A protective layer is provided to protect the material. This protective layer may be formed by directly coating the protective layer coating liquid on the stimulable phosphor layer, or by adhering a separately formed protective layer on the stimulable phosphor layer. It's okay. As the material for the protective layer, usual materials for the protective layer such as cellulose acetate, nitrocellulose, polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyester, polyethylene terephthalate, polyethylene, vinylidene chloride, and nylon are used. The thickness of these protective layers is generally preferably about 1 μm to 40 μm.

In the present invention, if the photostimulable phosphor dispersion has film-forming properties and the formed film has sufficient rigidity, the support and the protective layer described above are not necessary. There are cases.

The radiographic image conversion panel of the present invention provides obsolete sharpness and sensitivity when used in the radiographic image conversion method shown schematically in FIG. That is, in Figure 2, 21 is a radiation generator, 22 is a photoreceptor, 23 is a radiation ODj image conversion panel of the present invention, 24 is a photostimulation excitation light source, and 25 is a photostimulation excitation light source emitted from the radiation image conversion panel. A photoelectric conversion device that detects fluorescence, a device that reproduces the signal detected by 26!425 as an image, 27 a device that displays the reproduced image, 28 that separates photostimulation excitation and photostimulation fluorescence, This is a filter that allows only photostimulated fluorescence to pass through. It should be noted that the present invention is not limited to the above, as long as it can reproduce the optical information from 25 and 23 as an image in some form.

As shown in FIG. 2, the radiation from the radiation generating device 21 passes through the entire subject 22 and enters the radiation image conversion panel 23 of the present invention. . This incident radiation is absorbed by the stimulable phosphor layer of the radiation image conversion panel 23, its energy is accumulated, and an accumulated radiation image is formed. Next, this accumulated image is excited with photostimulation excitation light from the photostimulation light source 24 to emit stimulated luminescence. Since the radiation image conversion panel 23 of the present invention has regularity in the particle size distribution arrangement in the layer thickness direction of the photostimulable phosphor layer, the radiation image conversion panel 23 has a photostimulable phosphor layer that is photostimulable during scanning with the photostimulable excitation light. Diffusion of excitation light in the photostimulable phosphor layer is suppressed.

Since the intensity 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 25 such as a photomultiplier tube, and then converted into an image reproduction device 26.
By reproducing the image as an image and displaying it on the image display device 27, a radiographic image of the subject can be observed.

(Effects of the invention) ■ Since the arrangement of the photostimulable phosphor particles in the g-stimulable phosphor layer becomes more regular, the mean free path of the stimulable excitation light incident on the g-stimulable phosphor layer becomes shorter. As a result, the spread of the stimulated excitation light is well controlled, and the sharpness of the radiation image is significantly improved.

(2) Since large particles of photostimulable phosphor that are highly sensitive to radiation are arranged on the surface of the photostimulable phosphor layer, the radiation sensitivity of the radiation image conversion panel is improved.

■ The side where the large particles of the stimulable phosphor layer are arranged and the small stimulable phosphor particles arranged on the opposite side act as a reflective layer, which further improves the sensitivity of the radiation image conversion panel to radiation. .

(Example) Next, the present invention will be explained with examples.

Example 1 BaFBr with an average particle size of 10 μm and a dispersion of 5 μm:
8 parts by weight of the Eu stimulable phosphor and 1 part by weight of polyvinyl butyral resin were mixed and dispersed using 8 parts by weight of a solvent (cyclohexanone) to prepare a coating solution for the stimulable phosphor layer.

Next, on a surface plate placed horizontally, a layer with a thickness of 5 μm was separately formed.
A polyethylene film was placed as a protective layer, and frames for preventing the coating solution from flowing were provided around the four peripheries of the protective layer.

The coating solution is cast onto the preservation layer and allowed to stand overnight at 25°C to sediment and separate the stimulable phosphor particles);
An exhaustible phosphor layer was formed. Thereafter, the exhaustible phosphor FTM (above) was further dried, and a 200 μm thick polyethylene terephthalate film was adhered thereon as a support to form the radiation image conversion panel A of the present invention. ? )
is.

The thickness of the photostimulable phosphor layer of the radiation image conversion panel A of the present invention is 280 μm, and the particle size distribution arrangement of the cross section of the photostimulable phosphor layer is shown in FIG. 1 (h). Large particles were arranged on the protective layer side and small particles were arranged on the support side.

Next, the thus obtained radiation image conversion panel A of the present invention was irradiated with 10 mR of X-rays at a pressure of 80 kVp using a tube charge, and then scanned from the protective layer side with a He-Ne laser beam (633). The stimulated luminescence emitted from the photostimulable phosphor layer is photoelectrically converted using a photodetector (photomultiplier tube).
This was reproduced as an image by an image reproducing device to obtain an image on a display device. The modulation transfer function (MT
F) was investigated and the results are shown in Table 1.

Example 2 B with an average particle size of 10 μm and a dispersion of 5 μm in Example 1
The radiation p11 curved image conversion pattern of the present invention was produced in the same manner as in Example 1, except that a BaFBr: Eu photostimulable phosphor with an average particle diameter of 16 ttm and a dispersion of 7 μm was used instead of the aFBr: Eu photostimulable phosphor. B 4 ((4L fc.

1° of the 9-exhaustible phosphor of the radiation image r-image conversion panel B of the present invention
film thickness and particle size distribution arrangement of the cross section of the photostimulable phosphor layer]
The situation was the same as in Example 1.

Using the thus obtained radiation image conversion panel B of the present invention, M'l'F was prepared in the same manner as in Example 1. The results are shown in Table 1. Furthermore, the relative sensitivity was determined when the sensitivity of the radiation image conversion panel A of the present invention in Example 1 was set as 100. The results are also listed in Table 1.

Example 3 In Example 1, except that a BaFBr:Eu stimulable phosphor with an average particle diameter of 32 μm and a dispersion of IO μm was used instead of the BaFBr:gu Ifi stimulable phosphor with an average particle diameter of 10 μm and a dispersion of 5 μm. A radiation image conversion panel C of the present invention was obtained in the same manner as in Example 1.

The film thickness of the photostimulable phosphor layer and the particle size distribution arrangement in the cross section of the photostimulable phosphor layer of the uninvented radiation image conversion panel C were the same as in Example 1.

The MTF was investigated in the same manner as in Example 1 using the thus obtained radiation image conversion channel C of the present invention.The results are shown in Table 1. Relative sensitivity was determined when the sensitivity of panel A was set as 100.

The results are also listed in Table 1.

Example 4 In Example 1, average particle diameter 10 μm 1 dispersion 5 μn]
BaFBr: BaFBr with an average particle diameter of 12 μm and a dispersion of 2.5 μm instead of 8 parts by weight of Eu stimulable phosphor
: 2 parts by weight of Eu stimulable phosphor, average particle size 8 μm1
BaFo with a dispersion of 2.5 μm, g5 Br1,05:
Eu photostimulable phosphor 2 views, average particle size 4 μm 1 portion 2.0 μm LvBaFB'r #2 parts by weight of stimulable phosphor and average particle size 1 μm 1 BaFB with dispersion of 0.5 μm
r: A radiation image conversion panel D of the present invention was obtained in the same manner as in Example 1 except that the two Eu photostimulable phosphor bonds were used in a well-mixed manner.

The film thickness of the photostimulable phosphor layer of the uninvented radiation-pure image conversion panel D is the same as that of Example 1, and the particle size distribution arrangement of the four cross sections of the photostimulable phosphor is as shown in FIG. 1(a). It was like that.

Using the thus obtained radiation image conversion panel D of the present invention, M TF was investigated in the same manner as in Example 1. The results are shown in Table 1. Also, relative D! when the sensitivity of the radiation image conversion panel A of Example 1 is set to 100! ! I asked for degree. The results are also listed in Table 1.

Example 5 BaFBr with average particle size of 11 μm and dispersion of 1.5 μm:
Eul13 stimulable phosphor fluorescent part and 1 part of polyvinyl butyral resin are mixed and dispersed using 5 parts of a solvent (cyclohexanone) to prepare a coating solution for stimulable phosphor layer (to). adjusted. Similarly, average particle diameter 7 μm 1 dispersion 1,
5μm BaFBr: Eu excimable phosphor, average particle size 41tm, dispersion 1.0μm f3ap1.05T3r
o, 95: Eu ji'ii Exhaustible phosphor BaFBr:Eu with fluorophore diameter 1 μm 1 dispersion 05 μm It was adjusted.

Next, these coatings and rinses were placed in the same manner as in Example 1.
: Put the retention E' on top of the real left 11 as in Example 1 (7), (
One layer of a), (1), and (2) was coated one layer at a time, and drying was repeated to form a four-layer exhaustible phosphor layer17. A support was provided on this in the same manner as in Example 1 to obtain a radiation image conversion panel E of the present invention.

The thickness and structure of each layer of the radiation image conversion panel E of the present invention thus obtained are as follows.

Protection 70 (polyethylene) 5μ
m-1st photostimulable phosphor layer (average particle size 11 μm) 7
0 z bow (17) 701 #3 (f4) 70 #14
(#1) 70# Support (Polyethylene terephthalate) 200# I! In the same manner as in Example 1 using the radiographic image conversion panel E of the present invention,
I checked T.P. The results are shown in Table 1. Furthermore, the relative sensitivity was determined when the sensitivity of the radiation image conversion panel A of Example 1 was set as 100. The results are also listed in Table 1.

Example 6 The I'fhS F+ for applying the coating solution in Example 5 was (a), (7), (tsu), ni) and 1 and 2, except that the thickness of each layer after drying was as follows. The radiation a1.1 image summer change panel F of the present invention was attacked in the same manner as in Male Side 5.

Is it safe? (Horie Teren)
5μmη first med-exhaustible phosphor layer (average particle size 7) 1m
)3o#〃゛2〃 (I 11)
7o l〃3 (s 4
) 90#'4 (11)907
Y IM body (polyethylene terephthalate) 2
The MTF was examined in the same manner as in Example 1 using the radiation image conversion panel F of the present invention obtained with 00I. The results are shown in Table 1. In addition, the radiation image conversion panel A of Example 1
The relative sensitivity was determined when the sensitivity of 100 was set. The results are also listed in Table 1.

Comparative Example 1 BaFBr with average particle diameter of 10 μm and dispersion of 5 μm: E
8 parts by weight of stimulable phosphor and 1 part by weight of polyvinyl butyral resin
9: Gold part was mixed and dispersed using 4 parts by weight of a solvent (cyclohexanone), and the number of coatings for the stimulable phosphor layer was adjusted.

Next, the above coating solution was coated with bar caulk onto a polyethylene film as a protective layer with a thickness of 5 μm kept horizontally, and rapidly dried at 40°C to form a stimulable phosphor 1·η. Thereafter, a polyethylene terephthalate film with a thickness of 200 .mu.m was adhered as a support onto the stimulable phosphor layer to obtain a radiation image changing panel P for comparison.

The film thickness of the stimulable phosphor layer of the comparative radiation image conversion panel P was 280 .mu.n, and the particle size distribution in the cross section of the stimulable phosphor layer was random and no regularity was observed.

The MTF' of the comparative radiation image conversion panel P thus obtained was examined in the same manner as in Example 1. The results are shown in Table 1. In addition, the relative sensitivity p1 with respect to the radiation image conversion panel A of Example 1 was determined and is also listed in Table 1.

Comparative Example 2 In Comparative Example 1, B with an average particle diameter of 10 μm and a dispersion of 5 μm
aFBr Instead of Eu 'f4 exhaustive band fluorophore, average particle size 16 μm, dispersion 7 μm COBaFBr
: A comparative radiation image conversion panel Q was obtained in the same manner as in Comparative Series I except that Eu fJK exhaustible fluorophore was used.

The thickness of the exhaustible phosphor layer of the comparative radiation image conversion panel Q was 280 μm, and the particle size distribution in the cross section of the exhaustible phosphor layer was random and no regularity was observed.

Next, the comparative radial edge lli! obtained in this way! ! 7
The MTF' of the image conversion panel Q was examined in the same manner as in Example 1. The results are shown in Table 1. In addition, the relative sensitivity with respect to the radiation image conversion panel A of Example 1 was determined and is also listed in Table 1.

From Table 1 above, the radiation image A-I'' of the present invention gave an image with extremely high sharpness compared to the conventional comparative radiation image conversion panels P and Q. Furthermore, the radiographic image A-Fil of the present invention: a conventional comparative radiographic image conversion panel P,
Although it was more sharp than Q, it also had a high sensitivity and absorption, and was superior in this respect as well.

Note that the uninvented radiation image conversion panel C had the same or higher sharpness and sensitivity than other radiation image conversion panels of the invention, but the average particle size of the stimulable phosphor used The diameter was too large, resulting in poor granularity.

Example 7 In Example 1, the positional relationship between the support and the protective layer was reversed (
Thus, a radiation image conversion panel Of of the present invention was obtained in which small particles were arranged on the protective layer side.

Using the radiation image conversion panel G of the present invention thus obtained, the MTF was examined in the same manner as in Example 1. The results are shown in Table 2. Also, the radiation f! of Example 1! The relative sensitivity with image transformation panel A was determined.

The results are also listed in Table 2.

Table 2 From Table 2 above, it can be seen that the radiographic image conversion channel G of the present invention was as good as the radiographic image conversion channel A of the present invention in terms of sharpness, but the small particles were photostimulated. Since it is concentrated on the light incident side, the g degree against radiation is low.

[Brief explanation of the drawing]

FIGS. 1A to 1H are diagrams showing examples of the distribution arrangement of the phosphor particles in the phosphor layer of the radiation image conversion panel according to the invention in the size and pH direction. The figure is a schematic diagram illustrating a radiation image conversion method using the radiation image conversion panel of the present invention. 2] Radiation generator 22, subject 23, radiation image conversion panel 24, μ-excitation light source 28, filter substitute Person Patent Attorney Field 1) Sakura Parents. Figure 1 Figure 2

Claims (2)

[Claims] (1) In a radiation image conversion panel having a photostimulable phosphor layer formed by dispersing a photostimulable phosphor in a binder, particles of the photostimulable phosphor are dispersed on the surface of the radiation image conversion panel. A radiation image conversion panel characterized in that it has a distribution arrangement regarding particle diameters in a direction perpendicular to . (2) In a method for manufacturing a radiation image conversion panel having a photostimulable phosphor layer formed by dispersing a photostimulable phosphor in a binder, the radiation image conversion A method for producing a radiation image conversion panel, characterized in that a stimulable phosphor layer is formed by giving a distribution arrangement in terms of particle diameter in a direction perpendicular to the panel surface.