JPS62105099A - Radiation picture 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 (Field of Industrial Application) 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. It is something.

(Background of the invention) Radiation like X-ray images, Vi! Images are often used for disease diagnosis. This X +tJ W+ (!I!
In order to obtain this, the Xa that has passed through the subject is irradiated onto a phosphor layer (phosphor screen), thereby producing visible light, which is then used to produce a film using silver salt in the same way as when taking ordinary photographs. A so-called radiograph is used, which is a photo taken by irradiating the iron. However, in recent years, methods have been devised to directly extract images 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 the phosphor is then excited by, for example, light or thermal energy to obtain the illuminant. There is a method in which the radiation energy accumulated by a light body through absorption is emitted as fluorescence, and this fluorescence is detected and imaged.

Specifically, for example, U.S. Pat. It is shown. This method uses a radiation image conversion panel in which a stimulable phosphor layer is formed on a support. The object is transmitted through the light layer; - radiation is applied to accumulate radiation energy corresponding to the radiation transmittance of each part of the object to form a latent image, and then this stimulable phosphor layer is exposed to stimulable excitation light. By scanning, the radiation energy accumulated in each part is emitted and converted into light, and an image is obtained by an optical signal based on the intensity of this light. This final image may be reproduced as a copy or reproduced on a CRT.

The radiation image conversion tunnel having a stimulable phosphor layer used in this radiation image conversion method has a radiation absorption rate and a light conversion rate (including both), as in the case of radiography using a fluorescent screen described above. In addition, it is required that the image has good graininess and high sharpness, as well as high radiation sensitivity (5).

However, in general, a radiation image conversion panel having a stimulable phosphor layer uses a 1'+'171K layer containing granular stimulable phosphors with a particle size of about 1 to 30 μm and an organic binder as a support or a protector. Since it is created by coating and drying on a layer, the packing density of the stimulable phosphor is low ((filling) 1°11 ratio 50%),
In order to sufficiently increase the radiation sensitivity, it was necessary to increase the thickness of the stimulable phosphor layer (FIG. 6(a)).

On the other hand, the sharpness of the image in the radiation image conversion method 43 tends to be higher as the layer thickness of the stimulable phosphor layer of the radiographic image conversion method 43 is thinner. required thinning of the stimulable phosphor layer (6th
Figure (b)).

Furthermore, the graininess of the image in the radiation image conversion method is determined by local fluctuations in the number of radiation quanta (face mottles) or structural disturbances in the stimulable phosphor layer of the radiation image conversion tunnel (structural mottles). Therefore, when the layer thickness of the stimulable phosphor layer decreases, the number of radiation quanta absorbed by the stimulable phosphor layer decreases, causing an increase in muntin molecules and S
Architectural disturbances become apparent and structural mottles increase, resulting in a decrease in image quality. Therefore, in order to improve the graininess of the image, the stimulable phosphor layer needs to be thick.

That is, as mentioned above, in the conventional radiation image conversion panel, the sensitivity to radiation, the graininess of the image, and the sharpness of the image exhibit completely opposite tendencies with respect to the layer thickness of the stimulable phosphor layer. The radiation image conversion panels have been made with some trade-off between 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. The sharpness of images in radiation image conversion methods using stimulable phosphors is determined by the spread of stimulated luminescence of the stimulable phosphors in the radiation image conversion panel; It is not determined by the spread of the body's emission, but depends on the spread of the photostimulated excitation 5t within the panel. This is because in this Ω1 gland image conversion method,
Since the radiation image information stored in the radiation image conversion panel is retrieved in a time-series manner, it is desirable that all of the stimulated luminescence due to the stimulated excitation light irradiated at a certain time (tl) be captured and stimulated at that time. Recorded as the output from a certain pixel (xi, yi) on the panel that was irradiated with light. However, if the stimulable excitation light spreads within the panel due to scattering etc. and also excites the stimulable phosphor existing outside the irradiated pixel (xi, yi), the above (xt, yt)
This is because the output from a wider area than the pixel is recorded as the output from the pixel at tc. Therefore, at a certain time (tl), the stimulated luminescence due to the a-excitation light that was irradiated at fu'l('t+) is caused by the pixel ( xi, yi), there is no effect on the sharpness of the image obtained, no matter how widespread the light emission is.

Under these circumstances, several methods have been devised to improve the sharpness of radiographic images'J1. I came. For example, JP-A-5
5. Method of mixing white powder into the stimulable phosphor layer of a radiation pure image conversion panel described in No. 14fi/147, JP-A-5
The radiation image conversion panel described in No. 5-163500 is colored 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. method etc. but,
In these methods, improving sharpness inevitably leads to a significant decrease in sensitivity, and therefore cannot be said to be a preferable method.

On the other hand, Japanese Unexamined Patent Publication No. 59-60300 discloses a radiation image reading device using a radiation image conversion panel made of a transparent film made only of stimulable phosphor material.

The radiation image conversion panel used in this device is different from the above-mentioned stimulable phosphor layer in which a stimulable phosphor is dispersed in a binder; The phosphor layer becomes a transparent film, which reduces scattering of stimulated excitation light and improves image sharpness. However, since the stimulable phosphor layer of the panel is transparent, the stimulable excitation light incident on the phosphor layer is transmitted to the interface between the stimulable phosphor layer 71 and the support, or Stimulable phosphor layer 7
Since it is repeatedly reflected and diffused at the interfaces of the panel-constituting layers, such as the interface between No. 1 and the protective layer, causing halation, no significant improvement in image sharpness could be expected.

(Object of the Invention) The present invention has been made in view of the above-mentioned drawbacks and contradictions between the characteristics of a radiation image conversion panel using a JQL exhaustible phosphor. Both rLJ with improved sharpness and improved sharpness! The objective is to provide a radiation image conversion panel that provides the following.

Another object of the present invention is to use a conversion panel of 1 or E1 (
It's about doing.

In addition to the above object, another object of the present invention is to provide a method for manufacturing a radiation image conversion panel that satisfies the above object.

(Structure of the Invention) As a result of extensive research into the formation of a stimulable phosphor layer by a vapor deposition method, the present inventors have found that the stimulable phosphor layer is formed by finely crystallizing the stimulable phosphor. To make it opaque:
Therefore, the present invention was completed by discovering that the radiation image conversion panel exhibits high sharpness compared to conventional radiation image conversion panels having a transparent stimulable phosphor layer.

Hereinafter, ・Ukinb (, 1゜That is, the object of the present invention is to provide a radiation image conversion panel having at least one photostimulable phosphor layer on a support. A radiation image conversion panel characterized in that the layer is a vapor phase deposited layer of a photostimulable phosphor, and the layer is opaque to photostimulation excitation light, and a radiation image conversion panel providing the above characteristics. This is achieved by a manufacturing method.

In the present invention, opaque to the photostimulable excitation light refers to a case where the parallel light transmittance of the photostimulable phosphor layer to light in the wavelength range of the photostimulable excitation light is 60% or less, and preferably the parallel This refers to a case where the light transmittance is 45% or less, and more preferably a case where the parallel light transmittance is 30% or less.

Note that the parallel light transmittance referred to in the present invention is used to express the transmittance of a highly diffusive substance, and is expressed by the following equation.

T ((6) = X 100O (where T is the parallel light transmittance expressed in percent,
Io is the intensity of the parallel irradiation light incident on the sample, and Io is the intensity of the transmitted light of the component parallel to the irradiation light of the light transmitted through the sample. ) Also, the parallel light transmittance is measured by an apparatus schematically shown in FIG.

In the figure, 51 is a halogen lamp, 52 is a condenser lens, 53 is an aperture, 54 is a prism, and 58 is an irradiation lens, and 51 to 58 form an irradiation optical system. Also, the mark is a condenser lens, 63 is a prism, 6
5 is an aperture, 66 is a mirror, 67 is a bath filter, 68 is a photomultiplier tube, and these form a photometric optical system. Also, 55 is a beam splitter, 56 is a lens, 57 is a shutter, and 69 are mirrors, and these form an illumination optical system for the sample 59.

Further, 61 is a beam splitter, and 62 is a finder screen, which together form a finder.

The white light from the halogen lamp 51 is transmitted through the condenser lens 5
2, the irradiation field is restricted by the aperture 53, and the sample 59 is irradiated by the irradiation lens. The light transmitted through the sample 59 is collected by a condenser lens 60 and passed through an aperture 65, thereby becoming parallel transmitted light with only a component parallel to the irradiation light. The parallel transmitted light then passes through a bandpass filter 67 that transmits only light in the target wavelength range, and then enters a photomultiplier tube to determine the intensity of the parallel irradiation light. Parallel irradiation light intensity Io
can be measured by removing sample 59. The parallel light transmittance T is determined from the above Io and I. Note that the aperture ring 53 and U 65 move in conjunction with the aperture set 7 tink tire 64, and the size of the aperture ring is preferably about 500 μm x soo μm.

In the present invention, the vapor deposition method generally refers to physical
Vapor Deposition (PVD)
and Chemical Vapor Depositio
There are film forming techniques called tear n (CVD), such as vapor deposition, sputtering, and ion blating.

In an embodiment of the method for manufacturing a radiation image conversion panel of the present invention, it is preferable to use a vapor deposition method or a sputtering method in forming the stimulable phosphor layer.

Furthermore, when vapor deposition method or sputtering method A is used, penetration of the stimulable phosphor into the binder-containing layer of the panel support, its subbing layer, or protective layer, or the above-mentioned The binding agent of the subbing layer or protective layer may invade the stimulable phosphor layer formed by any of the methods, but the mixing of the stimulable phosphor and the binder due to the above-mentioned reasons may cause The following description will be simplified assuming that the layer is practically negligible, that is, the mixed layer is not generated by any of the methods described above.

The present invention will be explained in detail below.

In the radiation image conversion panel of the present invention, the photostimulable phosphor refers to a stimulable phosphor that is activated by a priori, thermal, mechanical, chemical, or electrical stimulus after being irradiated with the first light or high-energy radiation. It refers to a phosphor that exhibits stimulated luminescence corresponding to the amount of initial light or high-energy radiation irradiation due to (stimulated excitation), but from a practical point of view it is preferable that it exhibits stimulated luminescence due to stimulated excitation light of 500 nm or more. It is a phosphor that shows . Examples of the stimulable phosphor used in the radiation image conversion panel of the present invention include BaSO4:Ax (provided that at least one of A, DY, Tb and Tm) described in JP-A No. 48-80487; Yes, X is 0.001≦
x < 1 mol%. ), Mg5O described in JP-A-48-804-88: Ax
(However, A is either Ho or Dy,
0.001≦X≦1 mol%. ), 5rS described in JP-A-48-80489
O,: Ax (where A is at least one of DY, Tb and Tm, and X is 0.001≦x<
It is 1 mol%. ), Japanese Patent Application Laid-Open No. 1973
1-29889, Na25O,,C
Mn in aSO4 and B a SO, etc.

A phosphor containing at least one of Dy and Tb;
Bed described in JP-A No. 52-30487.

Fluorescent substances such as LiF, Mg5O, and CaF2, Li□B described in JP-A-53-39277, 07
: Fluorescent material such as Cul Ag, JP-A-54-4788
Li2O・('B20□) x described in No. 3
: Cu (where X is 2<x≦3), and Li2O
・(B20., ) x: Fluorescent material such as Cu, Ag (where X is 2 and
SrS described in No. 527: Ce, Sm
, SrS: Eu.

Sm, La20□S: Eu, Sm and (Zn
, Cd) S:Mn, a phosphor represented by X (where X is a halogen) is fired. Also, JP-A-55-12142
ZnS described in the No.: Cu, Pb phosphor, whose general formula is 13aO.xA/203. A barium aluminate phosphor represented by Eu (however, 0.8≦X≦10), and at least one of the general formula % Pb, Tl, Bi, and Mn, and X is 0.5≦x< It is 2.5. ) are alkaline earth metal silicate-based phosphors.

Moreover, the general formula is (Ba, -X-yMgxCay) FX: e
Eu” (where X is at least one of Br and Cl, and x, y, and e each satisfy O< x + y≦0.
The number satisfies the following conditions: 6, xy-#O and IO≦e≦5×10. ), the general formula of which is described in JP-A-55-12144 is LnOX: xA (where Ln represents at least one of La, Y, Gd and Lu, (X represents CI! and/or Br, A represents Ce and/or Tb, and X represents a number satisfying O < x < 0.1), JP-A-55-12
The general formula described in No. 145 is (Ba, -xMllx) FX: yA (however, M
n is at least one of Mg, Ca, Sr, Zn and Cd; X is at least one of Cl, Br and ■; A is gu, Tb, Ce, T
rrt.

Dy, Pr, Ho, Nd, Yb and'
At least one of Far, X and y are O≦X≦
It represents a number that satisfies the conditions of 0.6 and O≦y≦0,2. ), the general formula described in JP-A-55-84389 is BaFX: xCe, y
A (However, X is at least one of C1, Br and I, A is In, TI!, Gd, Sm and Zr
at least one of the following, and each of X and y is O<
x≦2XIO-1 and y≦5XIO-2.

), the general formula described in JP-A No. 55-160078 is ■ M FX・XA : yLn (where Mn is Mg, Ca, Ba, Sr,
At least one of Zn and Cd, A is 11eO
, MgO, Cab.

S r O+ B a O+ Z n O, A /20
3 + Yz”s + La2O3.

In2O3, Sin□, Tie, , ZrO2, G
em□, SnO□.

At least one of Nb2O, Ta205 and The2, Ln is Eu, Tb, Ce, Tm
, Dy, Pr, Ho.

Nd, Yt), Er, Sm, and Gd, X is at least one of Cl, Br, and I, and X and y are each 5
This is a number that satisfies the following conditions: 0≦X≦0.5 and 0<y≦0.2. ) rare earth element-activated divalent metal fluorohalide phosphor, whose general formula is ZnS: A,
CdS: A, (Zn, Cd) S: A, ZnS
: A, X and CdS: A, X (However, A is Cu,
Ag, Au or Mn, and X is halogen. ), Japanese Patent Application Laid-Open No. 57-148285
Any of the following general formula % formula % (where M and N are Mg, Ca, Sr, respectively) described in the No.
.

At least one of Ba, Zn and Cd, and X is F.

At least one of Cl, Br and I, A is Eu.

Tb, Ce, Tm, Dy, Pr, Ho, N
d, Yb, Er.

Represents at least one of Sb, TV, Mn and Sn. Also, X and y are 0 < x≦6.0≦y≦1
This is a number that satisfies the condition. ), one of the following general formula % formula % c In the formula, Re is at least one of La, Gd, Y, Lu, A is an alkaline earth metal, Ba, S
r, at least one of Ca, X and X' are F,
Represents at least one of C1 and Br. Also, X
and y is IXto-4<x<3Xto
-', lXl0-'<y<1x10-1, and n/m is 1x10-"<n/
The condition m < 7 X to-' is satisfied. ), and the following general formula % formula %: (However, Ml is Li, Na, K, Rb and C
At least one alkali metal selected from 5, M
■ is Be, Mg, Ca, Sr, Ba
, Zn, Cd, Cu, and Ni. Mi is Sc, Y,
Lr+, Ce, Pr, Nd, Pm.

Sm + Eu, Gd, Tb, Dy + H
o + E r , Tm + Yb.

It is at least one divalent metal selected from LIJ, ke', Ga, and In. x, x' and X"
is F, C/.

At least one halogen selected from Br and (2). A is Eu, Tb, Ce, Tm, Dy, P
r.

Ho, Nd, Yb, Er, Gd, Lu,
Sm, Y, Te.

At least one metal selected from Na, Ag, Cu, and Mg.

Also, a is a numerical value in the range of 0≦a<0.5, and b is 0
It is a numerical value in the range of ≦b<05, and C is a numerical value in the range of O×C≦02. ) and the like can be mentioned. In particular, alkali halide phosphors are preferred because they facilitate the formation of a stimulable phosphor layer by methods such as vapor deposition and sputtering.

However, 2. The photostimulable phosphor used in the radiation image conversion panel of the present invention is not limited to the above-mentioned phosphor, and when irradiated with radiation and then irradiated with photostimulation excitation light, the photostimulable phosphor emits photostimulable light. Any phosphor may be used as long as it exhibits the following.

The stimulable phosphor is formed into a stimulable phosphor layer that is opaque to the stimulable excitation light by finely crystallizing it and depositing it on a support in a vapor phase, or by an additional means, and according to the present invention. A radiation image conversion panel is created.

When the photostimulable phosphor layer of the radiation image conversion panel of the present invention has the above-mentioned fine crystals, the fine columnar crystals are formed in the photostimulable phosphor as shown in the electron micrograph of FIG. 1(a). It is preferable to have a structure that develops in the layer thickness direction.

In this case, each fine columnar crystal a, , a2. a3. Due to the light guiding effect of . As a result, the photostimulable excitation light 11 incident on the radiation image conversion panel reaches the deep part of the phosphor layer 13 without causing halation and diffusion in the photostimulable phosphor layer 13, and the photostimulable excitation light 11 enters the radiation image conversion panel. Since the phosphor is excited, the radiation sensitivity and graininess of the radiation image conversion panel are improved, and at the same time, the sharpness of the image is also improved. Further, the stimulated luminescence 12 generated deep in the photostimulable phosphor layer 13 of the radiation image conversion panel also reaches the surface of the phosphor layer 130 without being scattered and diffused. Improves sex.

When the photostimulable phosphor layer of the present invention has the above structure, the photostimulable phosphor layer microscopically shows the photostimulable excitation light due to the photoguiding effect of the columnar crystals of the photostimulable phosphor. However, since macroscopically it is an aggregate of fine columnar crystals, it becomes opaque due to diffuse reflection of the stimulated excitation light on the surface of the fine columnar crystal particles.

However, the stimulable phosphor layer of the radiation image conversion panel of the present invention only needs to be opaque, and does not necessarily need to have a fine columnar crystal structure.

The radiation image conversion panel of the present invention may be a photostimulable phosphor layer group consisting of one or more photostimulable phosphor layers containing at least one type of the above-mentioned photostimulable phosphors. good. Furthermore, the stimulable phosphors contained in each stimulable phosphor layer may be the same or different.

Next, a method for manufacturing a radiation image conversion panel of the present invention in which the photostimulable phosphor layer is opaque to photostimulable excitation light will be described.

The first method is a vapor deposition method. In this method, the support is first placed in a vapor deposition apparatus, the inside of the apparatus is evacuated, and the process is carried out for 10 minutes.
- The degree of vacuum should be approximately Torr. Next, at least one of the photostimulable phosphors is heated and evaporated by a resistance heating method, an electron beam method, or the like to deposit the photostimulable phosphor to a desired thickness on the surface of the support.

As a result, a photostimulable phosphor layer that is opaque to the photostimulable excitation light is formed, but it is also possible to form the photostimulable phosphor layer in multiple steps in the vapor deposition step. Further, in the vapor deposition step, it is also possible to perform co-evaporation using a plurality of resistance heaters or electron beams.

After the vapor deposition is completed, the radiation image conversion panel of the present invention is manufactured by providing a protective layer on the opposite side of the stimulable phosphor layer from the support side, if necessary.

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 vapor deposition method, the photostimulable phosphor raw material is codeposited using a plurality of resistance heaters or an electron beam, and the desired photostimulable phosphor is synthesized on the support at the same time. It is also possible to form a stimulable phosphor layer.

Furthermore, in the vapor deposition method, the object to be vapor deposited (support or protective layer) may be cooled or heated as necessary during vapor deposition. Further, the stimulable phosphor layer may be heat-treated after the vapor deposition is completed. In addition, in the vapor deposition method, 0
□+ Reactive vapor deposition may be performed by introducing a gas such as H2.

The second method is the Suba Tsutaring method. In this method, as in the vapor deposition method, the support is placed in a subinterning device, and then the inside of the device is once evacuated and heated to 1O-6 Torr.
The degree of vacuum is set to r Fp degree, and then an inert gas such as Ar or Ne is introduced into the sputtering apparatus as a gas for sputtering, and the gas pressure is set to about IQ-3 Torr.

Next, by sputtering using the photostimulable phosphor as a target (y), a photostimulable phosphor layer is deposited on the surface of the support to a desired thickness.

In the sputtering process, the stimulable phosphor layer can be formed in multiple steps as in the vapor deposition method, and a plurality of targets 7) each made of a different stimulable phosphor can be formed. It is also possible to form a stimulable phosphor layer by simultaneously or sequentially subjecting the target to a stimulable phosphor layer.

After the sputtering is completed, the radiation image conversion panel of the present invention is manufactured by providing a protective layer on the side of the stimulable phosphor layer opposite to the support, if necessary, in the same manner as in the vapor deposition method. Note that after forming the photostimulable phosphor layer on the protective layer,
A step of providing a support may also be taken.

In the sputtering method, a plurality of photostimulable phosphor raw materials are used as targets, and they are sputtered simultaneously or sequentially to synthesize the desired photostimulable phosphor on a support and simultaneously perform photostimulation. It is also possible to form a fluorescent phosphor layer. Further, in the sputtering method, reactive sputtering may be performed by introducing a gas such as 02°H2 as necessary.

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 is completed.

A third method is the CVD method. Moreover, there is an ion blating method as a fourth method.

In the manufacturing method of the present invention, the deposition rate of the photostimulable phosphor layer is preferably 0.2 μm/min to 300 μm/min. If the deposition rate is less than 0.2 μm/min, the stimulable phosphor layer tends to become transparent, and the productivity of the radiation image conversion panel of the present invention is undesirably low.

Further, if the deposition rate exceeds 300 μm/7 minutes, it is difficult to control the deposition rate, which is not preferable.

The thickness of the stimulable phosphor layer of the radiation image conversion panel of the present invention varies depending on the radiation sensitivity of the intended radiation image conversion panel, the type of stimulable phosphor, etc., but is 30 μm.
It is preferably selected from the range of ~1000 am, and 5
More preferably, it is selected from the range of 0 μm to 800 μm. If the layer thickness of the photostimulable phosphor layer is less than 30 μm, the radiation absorption rate will be extremely reduced, the radiation sensitivity will deteriorate, the graininess of the image will deteriorate, and the photostimulable phosphor will This is not preferable because it tends to become transparent, and the spread of the photostimulable excitation light in the lateral direction in the photostimulable phosphor layer increases significantly, which tends to deteriorate the sharpness of the image.

When the stimulable phosphor layer of the radiation image conversion panel of the present invention has fine columnar crystals, the size of the fine columnar crystals is such that the diameter of the columns is 1 μm to 300 μm, preferably 1 μm to 300 μm.
Selected from a range of 15,011 m. If the fine columnar crystals are too thin, the scattering properties of the stimulable phosphor layer will be increased, the excitation light will be diffused, and the sharpness of the image on the radiation image conversion panel will deteriorate, which is not preferable. In addition, if the fine columnar crystals are too thick, the photostimulable phosphor layer tends to become transparent, and the lateral spread of the photostimulable excitation light in the photostimulable phosphor layer increases, resulting in a sharp image. It is also undesirable because the properties deteriorate.

In the present invention, in order to make the photostimulable phosphor layer opaque to photostimulable excitation light, the phosphor layer is made up of fine crystals during vapor phase deposition of the photostimulable phosphor, as described above. Alternatively, the photostimulable phosphor layer may be colored with a dye, pigment, etc. that absorbs light in the photostimulable wavelength region.

Further, an absorption layer that absorbs light in the wavelength range of the photostimulable excitation light may be provided on the surface of the photostimulable phosphor layer opposite to the side on which the photostimulable excitation light is incident.

Furthermore, the above methods may be used in combination.

FIG. 2(a) shows the photostimulable phosphor layer thickness, the adhesion resistance amount of the photostimulable phosphor corresponding to the layer thickness, and the sensitivity to radiation for one example of the radiation image conversion panel of the present invention. relationship, second
Figure (b) shows the relationship between the thickness of the stimulable phosphor layer of the radiation image conversion panel example of the present invention and the sharpness of the image obtained by the radiation image conversion panel.

A vapor-deposited stimulable phosphor layer in which a phosphor is deposited as in the radiation image conversion panel of the present invention is a conventional dispersed radiation phosphor layer in which a phosphor is suspended and dispersed in a binder. Comparing it with an image conversion panel, it is clear that since it does not contain a binder, the adhesion resistance (filling rate) of the photostimulable phosphor is approximately twice that of a conventional radiation image conversion panel. The radiation absorption rate per unit thickness of the body layer is improved, and not only is the radiation sensitivity higher than that of conventional radiation image conversion panels, but the graininess of images is also improved.

Further, as in the photostimulable phosphor layer of the radiation image conversion panel of the present invention, fine crystals of the photostimulable phosphor are developed in the layer thickness direction of the photostimulable phosphor layer. If the directivity of the stimulated excitation light and the stimulated destination is excellent due to the light induction effect, it is possible to increase the thickness of the upper layer of the conventional dispersion type radiation image conversion panel.

Furthermore, since the vapor-deposited stimulable phosphor layer of the radiation image conversion panel of the present invention is opaque as described above, the stimulable phosphor layer does not allow the stimulable excitation light to pass through the stimulable phosphor layer in the lateral direction. Spreading is reduced and image sharpness is significantly improved.

The support used in the radiation image conversion panel of the present invention includes various polymeric materials, glass, gold fiber, cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, triacetate film, and polycarbonate. 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 surface of these supports may be smooth, or may be matte for the purpose of improving adhesion to the stimulable phosphor layer, or may be provided with a reflective layer or an absorbing layer. Further, the surface of the support body may have an uneven surface 31 as shown in FIG. 3(a), or may have a structure in which isolated tile-like plates 33 are laid out as shown in FIG. 3(b). In the case of FIG. 3(a), the stimulable phosphor layer is subdivided by uneven surfaces 31 as shown in the cross-sectional view of FIG. 3(C), so that the sharpness of the image is further improved. In the case of FIG. 3(b), the photostimulable phosphor layer is deposited while maintaining the outline of the tile-like plate 33 of the support, so that the photostimulable phosphor layer is deposited as shown in FIG. As shown in the cross-sectional view of (d), the image is composed of columnar blocks 35 of photostimulable phosphor separated by cracks 36, so that the sharpness of the image is further improved.

Furthermore, 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. In addition, the layer thickness of these supports varies depending on the material of the support used, but generally 80 μm ~
2000 tim, and more preferably 80 trm to 1000 μm from the viewpoint of handling.

In the radiation image conversion panel of the present invention, a protective layer for physically or chemically protecting the photostimulable phosphor layer is generally provided on the surface where the photostimulable phosphor layer is exposed. It's okay to be hit. This protective aFTI may be formed by applying I-liquid directly to the photostimulable phosphor layer as a protective layer coating, or by adhering a separately formed protective layer on the photostimulable 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 methacrylate, polyvinyl formal carbonate, polyester, polyethylene terephthalate, polyethylene, vinylidene chloride, and nylon are used. Moreover, this protective layer can be formed by depositing SiC, SiO□. SiN,
It may also be formed by laminating inorganic materials such as A/203.

The thickness of these protective layers is generally 0.1/1 m to 100 m.
About am is preferable.

The radiographic image conversion panel of the present invention provides excellent sharpness, graininess and sensitivity when used in the radiographic image conversion method shown schematically in FIG.

That is, in FIG. 4, 41 is a radiation generating device,
12 is a subject, 43 is a radiation image conversion panel of the present invention,
44 is a stimulated excitation light source; 45 is a photoelectric conversion device that detects stimulated luminescence emitted from the radiation image conversion panel; 46 is a device that reproduces the signal detected by 45 as an image; 47
48 is a device for displaying a reproduced image, and 48 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, its energy is accumulated, and an accumulated radiation image is formed.

Next, this accumulated image is excited by the stimulation destination from the stimulation excitation □ light source 44 and is emitted as stimulated luminescence. In the radiation image conversion panel 43, since the photostimulable phosphor layer is opaque to the photostimulable phosphor layer, the directivity of the photostimulable phosphor layer is high in the photostimulable phosphor layer, and the photostimulable phosphor layer is opaque to the photostimulable phosphor layer. Diffusion of the photostimulable phosphor layer during scanning with light is suppressed.

Since the strength of the emitted stimulated luminescence is proportional to the accumulated radiation energy arsenic, this optical signal is photoelectrically converted by a photoelectric conversion device 45 such as a photomultiplier tube, and the image reproduction device i\
46 and displayed as an image by the image display device 47, a radiographic image of the subject can be observed.

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

Example 1 A chemically strengthened glass having a thickness of 500 μm was placed in a vapor deposition apparatus as a support, and the support was heated to 150°C.

Next, water for electron beam evaporation? 9r IJA crucible/& intermediate alkali halide stimulable phosphor (RbB
r: 0.0006Te) and set it in the designated position.
then evacuate the evaporator to 2 x 10-6 To
rr vacuum degree and ru.

Next, a current is applied to an electron beam gun, and the Alkatuno 1 Ride stimulable phosphor is heated and evaporated by the electron beam method until the stimulable phosphor layer becomes 300 tim thick on the chemically strengthened glass. This was deposited to obtain a radiation image conversion panel A of the present invention. Note that the deposition rate was 5 μm/min.

After irradiating 10 mR of X-rays with a tube voltage of 80 KVp to the radiation image conversion panel A of the present invention thus obtained,
Stimulated excitation is performed with He-Ne laser light (633 nm), and the stimulated luminescence emitted from the photostimulable phosphor layer is photoelectrically converted with a photodetector (photomultiplier tube), and this signal is sent to an image reproducing device. The image was reproduced as an image by a computer and recorded on a silver halide film. The sensitivity of the radiation image conversion panel A to X-rays was investigated from the signal magnitude, and the modulation transfer function (MTF) and granularity of the image were investigated from the obtained images, as 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 of the present invention being taken as 100. Further, the modulation transfer function (MTF) is a value when the spatial frequency is 2 cycles/K11, and the graininess (good, average, bad) is indicated by (◯, △.×), respectively.

In addition, the parallel light transmittance of the photostimulable phosphor layer of the radiation image conversion panel A of the present invention was measured using the apparatus shown in FIG. Also listed in The wavelength of the light used was 630
It was nm.

Example 2 A chemically strengthened glass having a thickness of 500 μm was placed in a high frequency sputtering apparatus as a support, and the support was heated to 200°C. Next, alkali halide stimulable phosphor (0,95RbBr lIO
,05CsF: 0.001 Tl) was placed in a sputtering apparatus, followed by IXtO-Tor.
It was evacuated to a degree of vacuum of r. Sputtering was performed while introducing Ar gas as a sputtering gas, and a stimulable phosphor layer was deposited on chemically strengthened glass until the layer thickness reached 300 μm, thereby obtaining a radiation image conversion panel B of the present invention. Note that the sputtering speed was 4 μm/min.

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

Example 3 In Example 1, instead of using chemically strengthened glass as a support, a 500μ glass substrate whose surface was oxidized by an anodizing method was used.
A pore-sealing aluminum sheet with a thickness of 20 m is
The method of the present invention was carried out in the same manner as in Example 1, except that the aluminum oxide layer was subjected to heat treatment at 0° C. or higher to generate a large number of cracks, and a support having a structure of tiled plates separated by the cracks was used. A radiation image conversion panel C was obtained.

The radiation image conversion panel C of the present invention thus obtained was evaluated in the same manner as in Example 1, and the results were evaluated as
Also listed in the table.

Comparative Example 1 Alkali halide stimulable phosphor (RbBr: 0.000
Mix 6 parts by weight of 100% polyvinyl butyral resin and 1 part by weight of polyvinyl butyral resin using 5 parts by weight of a solvent (cyclohexanone).
The mixture was dispersed to prepare a coating solution for a photostimulable phosphor layer. Next, this coating solution was uniformly applied onto a chemically strengthened glass substrate with a thickness of 300 μm placed horizontally, and air-dried for 300 μm.
A stimulable phosphor layer with a thickness of μm was formed.

Comparative radiation image conversion panel P obtained in this way
was evaluated in the same manner as in Example 1, and the results are also listed in Table 1.

Table 1 As is clear from Table 1, the radiation image conversion panels A to C of the present invention have approximately It was twice as high, and the graininess of the image was excellent. This is because the radiation image conversion panel of the present invention is manufactured by a vapor deposition method, so the filling rate of the stimulable phosphor in the stimulable phosphor layer is higher than that of a comparative panel manufactured by coating. This is because the absorption rate of Xm is good.

Moreover, although the radiation image conversion panels A to C of the present invention have higher X-ray sensitivity than the comparative radiation image conversion panel P having the corresponding photostimulable phosphor layer thickness, they also have poor sharpness. It was excellent.

This is also because the photostimulable phosphor layer of the radiation image conversion panel of the present invention has a fine columnar crystal structure and the directivity of the photostimulated excitation light is high. This is because scattering in the stimulable phosphor layer is reduced.

In particular, in the radiation image conversion panel C of the present invention, the support is modified so that cracks in the support create cracks in the photostimulable phosphor layer, thereby dividing the photostimulable phosphor layer into smaller pieces. By doing so, it became possible to further suppress and reduce the scattering of the photostimulable excitation light in the photostimulable phosphor layer, and as a result, the sharpness of the image was further improved.

Example 4 A radiation image conversion panel D of the present invention was obtained in the same manner as in Example 2 except that the thickness of the photostimulable phosphor layer was 60 μm.

The four-ray radiation image conversion panel D of the present invention thus obtained was weighed in the same manner as in Example 1, and the results are shown in Table 2.

Example 5 In Example 4, the heating temperature of the support was 350°C,
A radiation image conversion panel E of the present invention was obtained in the same manner as in Example 4 except that the sputtering speed was 0.81+m/min.

The radiation image conversion panel E of the present invention thus obtained was evaluated in the same manner as in Example 1, and the results are also listed in Table 2.

Example 6 In Example 4, the heating temperature of the support was 350'C,
A radiation image conversion panel F of the present invention was obtained in the same manner as in Example 4 except that the sputtering speed was 20 μm/min.

The radiation image conversion panel F of the present invention thus obtained was evaluated in the same manner as in Example 1, and the results are also listed in Table 2.

Comparative Example 2 In Example 1, the layer thickness of the photostimulable phosphor layer was 20 μm.
and sputtering speed of 0.05/Jm/
A comparative radiation image conversion panel Q having a transparent photostimulable phosphor layer was obtained in the same manner as in Example 5, except that the phosphor layer was divided into two parts.

Comparative radiation image conversion panel Q obtained in this way
was evaluated in the same manner as in Example 1, and the results are also listed in Table 2.

Table 2 As is clear from Table 2, compared to the radiation image conversion panel D of the present invention, the comparative panel Q had poorer image sharpness despite the thinner photostimulable phosphor layer. . This is because the comparative panel Q has a transparent photostimulable phosphor layer, so that the photostimulable excitation light spreads widely in the lateral direction.

In the panel Q for comparison, the transparency of the stimulable phosphor layer is lost when the sputtering speed is increased, so high-speed sputtering cannot be performed and productivity is extremely poor.

Note that the radiation image conversion panel D and TIE of the present invention.

As for F, sharpness tended to decrease as parallel light transmittance improved.

Example 6 In Example 1, an alkaline earth fluoride halokenide phosphor (BaF'Br: 0.002
A radiation image conversion panel G of the present invention was obtained in the same manner as in Example 1 except that ELI) was used.

The thus obtained radiation image conversion panel G of the present invention was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

(Effects of the Invention) As described above, according to the present invention, the radiation image conversion panel of the present invention is a stimulable phosphor layer in which a stimulable phosphor is deposited in a vapor phase, and Since it is opaque to the photostimulable excitation light, the horizontal spread of the photostimulated excitation light in the photostimulable phosphor layer is suppressed, and the sharpness of the image is deteriorated due to the spread of the photostimulated excitation light. can be prevented.

In addition, when the photostimulable phosphor layer of the present invention has a fine columnar crystal structure as a result of vapor deposition The directionality of light emission is improved,
Since stimulated luminescence from inside the photostimulable phosphor layer can be detected, sensitivity is improved, and at the same time scattering of photostimulated excitation light is reduced, so that the detailed description of images is improved.

Further, according to the present invention, since a binder is not included in the photostimulable phosphor layer, the filling rate of the photostimulable phosphor is improved, and the sensitivity to radiation is improved, and at the same time, the quantum mottle caused by radiation is Since the structural mottle of the photostimulable phosphor layer is reduced, the graininess of the image is improved.

The present invention has extremely great effects and is industrially useful.

[Brief explanation of drawings]

FIG. 1(a) is an electron micrograph of a cross-section of the stimulable phosphor layer of the present invention, and FIG. 1(b) is an explanatory diagram of the light guiding effect in the phosphor layer. Figure 2 shows the layer thickness (after deposition) and relative sensitivity of the photostimulable phosphor in one example of the radiation image conversion panel of the present invention ((a) in the same figure).
and MTF ((b) in the same figure). Incidentally, FIGS. 6(a) and 6(b) show the characteristics of the conventional dispersed stimulable phosphor layer corresponding to FIGS. 2(a) and 2(b). FIG. 3 is a cross-sectional view schematically showing the surface of the support according to the present invention on which the stimulable phosphor is deposited (FIG. 3 (a) and (b)) and the state after the deposition. . FIG. 4 is a schematic diagram of a radiation image conversion method using the radiation image conversion panel of the present invention. FIG. 5 is a schematic diagram of an apparatus used for measuring parallel light transmittance according to the present invention. FIG. 7 is a sectional view showing halation in a radiation image conversion panel having a transparent stimulable phosphor layer, and is located in the engraving ζ of the drawing. 11... Stimulated excitation light, 12... Stimulated luminescence, 13... Stimulated phosphor layer, 31 and 32
...... Support, 33... Tile plates 34 and 35... Stimulable phosphor layer, 36
......Crack, 41...Radiation generating device, 42...
...Subject, 43... Panel 44... Stimulative excitation light source, 48...
····filter. Applicant Roku Konishi Photo Industry Co., Ltd. No changes) Figure 2 (b) Figure 4 Figure 5 51 Horn lamp 53, 65 Ryo1\-Key 59 1 person Keito Figure 6 (a) ) (b) ° ′”°0赫子、) Fig. 7 71 Speed B 已 9Y 浞聚性体凫手臉, ″、Mou1E Printing: (Method) % Formula % 2. Name of the invention Radiographic image Conversion panel and its manufacturing method 3, relationship with the person making the correction Patent issued: 9n IF Office Konishiroku Photo Industry Co., Ltd. 11, 1-26-2 Nishiorishuku, Shinjuku-ku, Tokyo (Telephone: 0.125 -83-152
1) Patent Division/T, date of amendment order, 1985 1713 [-] (] Shipping date: January 2, 1985
On the 8th, 5th, in the "Brief explanation of the drawings" column and "Drawing" 6, Contents of the amendment (1) 1. Brief explanation of the drawings in the amendment material description, ,
) is an electron micrograph of ---,'' is replaced by ``Figure 1 (
a) is an electron micrograph of a cross-section of the crystal structure of the stimulable phosphor layer of the present invention.'' (2) Correct the tracing of Figures 1 (a) and (b) in the "Drawings" on the attached sheet.

Claims (2)

[Claims] (1) In a radiation image conversion panel having at least one stimulable phosphor layer on a support, the stimulable phosphor layer is a layer in which a stimulable phosphor is deposited in a vapor phase, and A radiation image conversion panel characterized in that the layer is opaque to stimulated excitation light. (2) In manufacturing a radiation image conversion panel having at least one stimulable phosphor layer on a support, the stimulable phosphor layer is formed by vapor phase deposition of the stimulable phosphor layer. A method for producing a radiation image conversion panel, characterized in that the stimulable phosphor layer is made opaque to stimulable excitation light.