JPS6172091A - Radiation image conversion method and radiation image conversion panel using therefor - Google Patents

Abstract

PURPOSE:To carry out the radiation image conversion in high sensitivity, using a fluorescent material having high luminance and exhibiting accelerated phosphorescence, by exposing a specific fluorescent material exhibiting accelerated phosphorescence to radiation, exciting the fluorescent material with electromagnetic wave, and detecting the emitted fluorescent light. CONSTITUTION:Radiation transmitted through the object to be photographed or emitted from the object is absorbed in a fluorescent material of formula (MI is Li, Na, K, Rb or Cs; MII is Be, Mg, Ca, Sr, Ba, etc.; MIII is Sc, Y, La, Ce, Pr, etc.; X, X' and X'' are F, Cl, Br or I; A is BeO, MgO, Al2O3, Sio2, Nb2O5, etc.; B is Eu, Tb, Ce, Tm, Dy, etc.; 0<=a<0.5; 0<=b<0.5; 0<c<0.5; 0<d<=0.2) exhibiting accelerated phosphorescence. The fluorescent material is excited with electromagnetic wave consisting of visible light and/or infrared radiation to effect the emission of the radiation energy stored in the fluorescent material. The emitted fluorescent light is detected to effect the radiation image conversion.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a radiation image conversion method and a radiation image conversion panel included in the method. The present invention relates to a radiation image conversion panel used in the method.

(Prior Art) Conventionally, a so-called radiographic method using a silver salt has been used to obtain a radiographic image, but a method of imaging a radiographic image without using a silver salt has become desired.

As an alternative to the above-mentioned radiographic method, the radiation transmitted through the object is absorbed by a phosphor, and then this phosphor is excited with a certain kind of energy, and the radiation energy M product of this phosphor is converted into fluorescence. A method is being considered in which the fluorescent light is emitted and the fluorescence is detected and imaged. A specific method has been proposed in which a thermofluorescent phosphor is used as the phosphor and thermal energy is used as the excitation energy to convert a radiation image (British Patent No. 1,462.769 and Japanese Patent Application Laid-Open No. 1983-1989). No. 29889). This conversion method uses a panel with a thermoluminescent phosphor layer formed on a support.
The thermofluorescent phosphor layer of this panel absorbs the radiation that has passed through the subject, producing a radiation energy M product that corresponds to the intensity of the radiation, and then heating the thermofluorescent phosphor layer to generate accumulated radiation. It extracts energy as a signal and obtains an image based on the intensity of this light. However, since this method heats up when converting accumulated radiation energy into a signal, it is absolutely necessary that the panel be heat resistant and not deformed or altered by heat. There are major restrictions on the materials of the fluorescent phosphor layer and the support. The radiation image conversion method using a thermofluorescent phosphor as the phosphor and thermal energy as the excitation energy has major drawbacks in terms of application. On the other hand, a radiation image conversion method is also known that uses a panel in which a stimulable phosphor layer is formed on a support and uses visible light and/or infrared rays as excitation energy (US Pat. No. 3, 89
5, No. 527). This method does not require heating when converting the accumulated radiation energy into optical signals as in the above method, and therefore the panel does not need to be heat resistant. I can say that.

A conventional thermofluorescent phosphor is LiF:Mg.

Phosphors such as r3 aS 04:M n + CaF 2:D y are known. In addition, as a stimulable phosphor that uses visible light or infrared rays as excitation energy,
KCI:T1 or BaFX:Eu2+ system (X: Cl, Br, I
) phosphors, etc. are known.

By the way, when the i'+if radiation image conversion method is used for XR image conversion for the purpose of medical diagnosis, it is desirable that the method be as sensitive as possible in order to reduce the patient's exposure to radiation. Therefore, it is desirable that the stimulable phosphor used in this method has as high a luminance as possible due to stimulation.

In addition, in the above method, in order to increase the operating efficiency of the system, it is necessary to increase the reading speed of the radiation image, and therefore the stimulable phosphor used in the method has a stimulable luminescence response of 3. Fast speed is desirable.

Furthermore, in the above method, the radiographic image conversion panel is generally used repeatedly after erasing the afterimage caused by the previous use, but in order to improve the operating efficiency of the system, the afterimage erasing time of the radiographic image conversion panel should be short. Desirably, the stimulable phosphor used in the method has a high afterimage erasing speed.

However, the above-mentioned stimulable phosphors are not fully satisfactory in terms of stimulated luminance, response speed of stimulated luminescence, and afterimage erasing speed, and improvements in these are desired.

Furthermore, in the method, it is desirable that the reading device for reading the radiation green image be small, low-cost, and simple;
For this purpose, an A r+ laser or a He N laser is used as an excitation light source.
It is more impractical to use a semiconductor laser than to use a slave such as an e-laser, and therefore, the stimulable phosphor used in this method is
It is desirable to have a photostimulated excitation spectrum suitable for (n+ or higher).

However, the above-mentioned photostimulable phosphor hardly exhibits stimulated luminescence at the oscillation wavelength of a semiconductor laser, and a longer wavelength of the stimulated excitation spectrum is desired.

A phosphor represented by the following general formula ([1)] has been proposed as a stimulable phosphor that satisfies the above-mentioned requirements.

General formula (II) M 'X-aM "X 2' ・bM ff1X z
”: cA However, M' is at least one kind of alkali metal selected from Li, Na, Rb and Cs.

Ml is B e v M g + Ca + S r +
B a t Z n + Cd v Cu and Ni
At least one divalent metal selected from MII
Il, tsc, Y, La, Ce, Pr, Nd, Pm, S
m.

Eu, Gd, TbtDy+Ho+Er+Tm+Yb, L
At least one divalent metal selected from u, AI, Ga, and In. x, x' and X'' are F, CI,
At least one type of halogen selected from BrB and (2). A is Eu+Tb+CetT+*tDyvPrtH
o+NdtYb+E r t G d + L u +
S m + Y t T I + N a, A g
t At least one metal selected from Cu and Mg.

Also, a is a numerical value in the range of 0≦a<0.5, and b is O≦
It is a numerical value of the sheath circumference of b<0,5, and C is a numerical value in the range of 0<c≦0.2.

The alkali halide-based stimulable phosphor represented by the above general formula ([1)] is superior to conventional stimulable phosphors such as BaFBr:Eu in terms of stimulable luminance, stimulable luminescence response speed, and afterimage erasing speed. Better than the body. However, on the other hand, since the alkali halide phosphor represented by the above general formula (■) is hygroscopic, it has the drawback that the luminance of photostimulated light decreases over time, and improvement of this problem is desired. . Moreover, it goes without saying that it is desirable that the luminance of light emission due to photostimization be higher.

(Object of the Invention) The present invention involves making a stimulable phosphor absorb radiation transmitted through an object, and then exciting the stimulable phosphor with LiT visual rays and/or electromagnetic waves in the infrared range to produce the stimulable phosphor. In a radiation image conversion method in which the radiation energy accumulated in a stimulable phosphor is emitted as fluorescence and this fluorescence is detected, a highly sensitive radiation image using a stimulable phosphor that exhibits a higher luminance stimulated luminescence. The purpose is to provide a conversion method.

Another object of the present invention is to provide a radiation image conversion method using an alkali halide stimulable phosphor with excellent moisture resistance, in which a decrease in stimulated luminance over time is not a problem.

A further object of the present invention is to provide a radiation image conversion panel that satisfies the above objects.

(Structure of the Invention) In accordance with the object of the present invention, the present inventors have discovered a stimulable phosphor that exhibits high-intensity stimulated luminescence and has excellent moisture resistance without causing a problem of decrease in the luminance of stimulated luminescence over time. As a result of various studies, the radiation transmitted through or emitted from the subject is absorbed by a stimulable phosphor containing an alkali halide stimulable phosphor represented by the following general formula (I), and then, The method is characterized in that the stimulable phosphor is excited by electromagnetic waves selected from visible light and infrared rays, the radiation energy accumulated in the stimulable phosphor is emitted as fluorescence, and this fluorescence is detected. The objects of the present invention are achieved by a radiation image conversion method and by a radiation image conversion panel that satisfies the above requirements.

General formula <1) M'X-aM"X2'・bM"X3" ・cA:d
B However, M' is at least one kind of alkali metal selected from Li, Na, Rb and Cs.

M'' is BetMgsCatSrtBatZntCdtC
At least one divalent metal selected from u and Ni. Mn' is Sc, Y, La, Ce, Pr, Nd, P
+m, Sm.

Eu+Gd, TbwDytHo+ErtT+mtYbv
At least one trivalent metal selected from LutAl, Ga, and In.

x, x' and x'' are at least one type of /% rodene selected from F, CI, Br and I. A is BeO
, Mg0tCaO, SrO+BaO*ZnO+Al20
t+Y, O:l, La20. , rnzO, , SiO2,
Ti0z, ZrO2゜G eo, S no 2
．． N b20 St T a20 s and The□
A metal oxide (also a type of metal oxide) selected from

B is Eu*Tb+Ce, Tm, DytPr+Ho+Nd
tYbtEr+Qd, Lu, S, m, Y, TI+Na+
It is at least one metal selected from Ag, Cu and Mg. Also, a+bwc and d are respectively 0≦a<0.
5.0≦b<0.5.0 <c<0.5.0<d≦0.
It is a number in the range of 2.

That is, when the alkali halide stimulable phosphor having the composition according to the present invention is excited by electromagnetic waves in the visible to infrared region, it exhibits stimulated luminescence with higher brightness than conventional alkali halide stimulable phosphors, and moreover, This provides a radiation image conversion method in which a decrease in stimulated luminance due to radiation does not pose a problem.

The radiation #1 image conversion method of the present invention is carried out by using a radiation image conversion panel containing the stimulable phosphor of general formula (I).

A radiation image conversion panel basically consists of a support and at least one stimulable phosphor layer provided on one or both sides of the support. Generally, a protective layer for chemically or physically protecting the stimulable phosphor layer is provided on the surface of the stimulable phosphor layer opposite to the support. That is, the radiation #i image conversion method of the present invention provides a radiation image that essentially consists of a support and at least one stimulable phosphor layer containing a stimulable phosphor provided on the support. A radiation image conversion panel in which the vf characteristic is that at least one of the stimulable phosphor layers contains a photostimulable amount-enhancer represented by the general formula (I). It is carried out using

The stimulable phosphor of the general formula (I) absorbs radiation such as X11A, and then is irradiated with light in the visible or infrared region, preferably in the wavelength region of 500 to 900 nm (Fih luminescence). Shows stimulated luminescence. Therefore, the radiation transmitted through the subject or emitted from the subject is absorbed by the stimulable phosphor included in the stimulable phosphor layer of the radiation image conversion panel in proportion to the radiation dose, and the radiation image conversion panel The subject or the radiological image of the subject is displayed on the panel.
It is formed as a latent image that accumulates radiation energy. When this latent image is excited with excitation light in a wavelength range of 500 nm or more, it exhibits stimulated luminescence that is proportional to the accumulated radiation energy, and by photoelectrically reading this stimulated luminescence, it can be determined that the radiation energy has been accumulated. It becomes possible to turn a latent image into a visible image.

The present invention will be explained in detail below.

FIG. 1 schematically shows an embodiment of the radiation image conversion method of the present invention in which the stimulable phosphor represented by the general formula (I) is used in the form of a radiation image conversion panel.

In the fjS1 diagram, 11 is a radiation generating device, 12 is a subject, and 13 is radiation #1 image conversion having a visible light or infrared light stimulable phosphor layer containing a stimulable phosphor represented by the general formula (I). panel, 14 is radiation image conversion panel 1
3, an excitation light source for emitting the radiation latent image as fluorescence; 15, a charge conversion device that detects the fluorescence emitted from the radiation image conversion panel 13; and 16, a charge conversion signal detected by the photoelectric conversion device 15 as an image. Reproducing device, 17
18 is a device for displaying a reproduced image, and 18 is a filter for cutting reflected light from the light source 14 and transmitting only the light emitted from the radiation image conversion panel 13.

Although FIG. 1 is an example of obtaining a radiographic image of a subject, the subject 12 itself emits radiation (subject).
In this case, the radiation generating device 11 is not particularly required. Further, the photoelectric conversion device 15 and subsequent devices may be any device as long as it can reproduce the optical information from the panel 13 as an image in some form.
It is not limited to the above. As shown in Figure tjs1, when the subject 12 is placed between the radiation generator 11 and the radiation image conversion panel 13 and irradiated with radiation, the radiation passes through each part of the subject 12 as the radiation transmittance changes, and the transmitted image (that is, an image of the intensity of radiation) enters the radiation image conversion panel 13. This incident transmitted image is absorbed by the stimulable phosphor layer of the radiation image conversion panel 13, and a number of electrons/holes are released in proportion to the amount of radiation absorbed into the stimulable phosphor layer. This is accumulated at the trap level of the stimulable phosphor.

That is, a latent image is formed by multiplying the energy of the radiographic image by 1. This latent image is excited with light energy and made visible. That is, the stimulable phosphor layer is irradiated with light 'a14 that emits light in the visible or infrared region, and the electrons accumulated at the trap level are expelled, and the accumulated energy is converted into fluorescence. Let it be released.

The intensity of this emitted fluorescence is proportional to the number of accumulated electrons and/or genuine bills, that is, the intensity of radiation energy absorbed by the stimulable phosphor layer of the radiation image conversion panel 13, and this optical signal is For example, a photoelectric conversion device 15 such as a photomultiplier tube converts the signal into an electrical signal, an image processing device 16 reproduces it as an image, and an image display device 17 displays this image. It is more effective to use an image processing device 16 that is capable of not only reproducing electrical signals as image signals, but also capable of so-called image processing, image calculation, image storage, storage, etc.

Furthermore, when exciting with light energy in the method of the present invention,
It is necessary to separate the reflected excitation light and the fluorescence emitted from the stimulable phosphor layer, and the charging converter that receives the fluorescence emitted from the stimulable phosphor layer generally has a short wavelength of 600 nm or less. It is desirable that the fluorescence emitted from the X1II exhaustible phosphor layer has a spectral distribution in the short wavelength region as much as possible because of its high sensitivity to light energy.

The emission wavelength range of the stimulable phosphor used in the method according to the present invention is 300-500 nm, while the excitation wavelength range is 50 nm.
Since it is 0 to 900n+s, the above conditions are satisfied at the same time.

That is, all of the stimulable phosphors used in the present invention exhibit light emission having a main peak at 500 nm or less, and ω
Since it is easy to separate the spectral sensitivity from the h-receiver and also matches well with the spectral sensitivity of the photoreceiver, it is possible to efficiently receive light and increase the sensitivity of the image-receiving system.

The stimulated excitation light source 14 used in the method of the present invention includes:
A light source is used that includes the stimulable excitation wavelength of the stimulable phosphor used in the radiation image conversion panel 13.

In particular, when a laser beam is used, the optical system becomes simple and the intensity of the excitation light can be increased, so that the stimulated luminescence efficiency can be increased and more favorable results can be obtained. Lasers include He-Ne laser, He-Cd laser, A
"Ion laser, Kr ion laser, N2 laser, YA
Examples include G laser and its 12th harmonic, ruby laser, semiconductor laser, various dye lasers, and metal vapor lasers such as copper vapor laser. Usually, a continuous oscillation laser such as a He Ne laser or an Ar ion laser is desirable, but a pulse oscillation laser can also be used if the pulse is synchronized with the scanning time of one pixel on the panel. Furthermore, when using the separation method using the delay in light emission as shown in Japanese Patent Application Laid-Open No. 59-22046 without using the filter 18, it is better to use a pulsed laser than to modulate using a continuous wave laser. preferable.

Among the various laser light sources mentioned above, semiconductor lasers are most preferred because they are small, inexpensive, and do not require a t-adjustment.

Since the filter 18 transmits the stimulated luminescence emitted from the radiation image conversion panel 13 and cuts off the excitation light, the filter 18 is designed to match the stimulated emission wavelength of the stimulable phosphor contained in the radiation image conversion panel 13. It is determined by the combination of the wavelengths of the and l1jh light sources 14.

For example, in the case of a practically preferable -III combination in which the stimulated excitation wavelength is 500 to 90' Onm and the stimulated emission wavelength is 300 to 500 nm, the filter may be, for example, Toshiba C-39, C-40, V-40, V-42, V-44
, 7-54.7-59 manufactured by Corning, BG-1, BG-3, BG-25, BG-37 manufactured by Spect o Film
A purple to blue color filter such as BG-38 can be used. Furthermore, by using an interference filter, it is possible to select and use a filter with arbitrary characteristics to some extent.

As the charging conversion device 15, a phototube, a photomultiplier tube, 7
Any device capable of converting a change in light amount into a change in an electrical signal, such as an otodiode, a 7 ototrunk transistor, a solar cell, or a photoconductive element, may be used.

Next, a radiation image conversion panel used in the radiation image conversion method of the present invention will be explained.

As described above, the radiation image conversion panel comprises a support and at least one vr1 stimulable phosphor layer containing a stimulable phosphor represented by the general formula (I) provided on the support. configured.

In the photostimulable phosphor represented by the general formula (I), Ml in the general formula (I) is L from the viewpoint of stimulated luminescence brightness.
For i, Na, at least one alkali metal selected from Rb and I/Cs is preferable, and at least one alkali metal selected from Rb and Cs is preferable. M" is preferably at least one alkaline earth metal selected from Ca, Sr, and Ba, and Mw is Y.

At least one trivalent metal selected from La, Sm, Gd, Lu, AI, Ga and In is preferred. As X'', at least one kind of halogen selected from F, CI, and B'' is preferable.
and the b value representing the content rate of M'X,'' are respectively,
It is preferably selected from the range of 0≦a<0.4 and 0≦b≦10−2. When the a value is a>0.5, the stimulated luminescence brightness decreases rapidly, which is extremely undesirable.

In addition, as metal oxide A, Mg0tAI203°5
Preferably, it is at least one of I02 and TiO2. The C value representing the content of A is 0<c≦0.
It is preferable that it is 2.

In the general formula (I), the activator B is EuwC
At least one metal selected from e*SmtT IvAg*Cu and Na is preferred. Further, from the viewpoint of stimulated luminescence brightness, it is preferable that the d value representing the amount of the activator is selected from the range of 1o-8≦d≦0.1.

Stimulable phosphor M'X-aMIIχ2' according to the present invention
bM l1lX y” ·cA :dB is manufactured, for example, by the 9I manufacturing method described below.

First, the stimulable phosphor raw materials are: 1) LiF, LiC1, Li[lr,
Li1. NaF, NaC1, Na mouth.

Nap, KF, KCI, KBr, K1. Rb
F, RbC1, Rh0r.

Rbl, CsF, CsCl, CsBr, Cs[
One or more of the following, U) BeF2+ BeCIzt BeBr2. B
e12+ MgF2t MgCl□+MgBr29Mg
[2w CaF2w CaCl2+ CaBr2w C
a12tSrF2vSrCl. , 5rBr2. Sr.
l□, BaF2. BaC12t lIaBr2wB
aBr2 * zl12ot Ba12. ZnF2-
ZnCl2. ZnBr2IZnlz-CdF2.
CdCl:, CdBr2+ Cd1zt Cut2.
CuCIz, CuBrz.

Cul, NiF2. NiCl□, NiBr2. NlI
ScF3.5cCI, -5cBr=, 5cl
it YFy, YCIs-YBra.

Y13. LaF3t LaCI=y LaBr3.
L, al, CeFit Ce13-CeBr3.
Ce11. PrFl, PrCl1- PrBr5. P
r1z, NdFi.

NdCl, NdBr=, Nd13. P+
*F3. PmCl,, PmBr,.

PII113- 5IIF3. 5IIICI3.
SmBr3. 5III3- EuF,, EuC1z
-EuBrit Eu1. , GdFx-GdCl
1-GdBrn, Gd1s, TbF*-TbC
lit TbBr=, Tb1it DyF*t
DyCl5tDyBr: +tDylztHoF3t
HoC1=t Hour's HOI3. Er
Fiw ErCl,.

ErBr)t Er1=, TmF,, TmCl1*
TmBr,, Tm13. YbFz-YbCI3. Yb
1) r=,Ybl,,LuF,,LuCl3. Lu13
r.

Lul,, ^IF,, AlCl,, ^IB
rH^+13- GdFs, GaCl-.

GdBrt-Gd1z-[nF,, InCl5-
One or more types of 1nBr, , Inl, and N) Bed, Mg0v Cab, 5rOv Ba
1t Zn0w^1zOi-Y2O2-LIL20:l
, In□03. Sin□, Ti0z, ZrO2
, Ge0z, 5nOz-Nb205. One or more of Ta205 and The□.

V) Eu compound group, Tb compound group, Ce compound group, Tm
Compound group, oy compound group, Pr compound group, )0 compound group, Nd compound group, yb compound group, Er compound group, Cd compound group, Lu compound group, Sa + compound group, Y compound group,
One or more types of activator raw materials selected from the TI compound group, the Na compound group, the Heg compound group, the Cu compound group, the M compound group, and the compound group are used.

MfX-aMII×2' ・bMmX, Li ・cA:d stoichiometrically represented by general formula (I)
In B, 0≦a<0.5 preferably ()≦a
≦0.4, O≦b<0.5 preferably 0≦b≦1
0-2.0<c<0.5 Preferably O<c≦0.
2.0<d<0.2 Preferably lj: 10-6≦C
The above stimulable phosphor raw materials I) to (iv) are weighed so as to have a mixed composition of ≦0.1, and thoroughly mixed using a milk needle, ball mill, mixer mill, etc.

Next, the obtained stimulable phosphor raw material mixture is filled into a heat-resistant container such as a quartz crucible or an aluminum crucible, and fired in an electric furnace. A suitable firing temperature is 500 to 1000°C. Although the firing time varies depending on the filling amount of the raw material mixture, the firing temperature, etc., 0.5 to 6 hours is generally appropriate. The firing atmosphere may be a weakly reducing atmosphere such as a nitrogen gas atmosphere containing a small amount of hydrogen gas, a carbon dioxide gas atmosphere containing a small amount of carbon monoxide, or a neutral atmosphere such as a nitrogen gas atmosphere, an argon gas atmosphere, or an ambient atmosphere. Preferably, after firing once under the above firing conditions, the fired product is taken out of the electric furnace and pulverized, and then the fired product powder is again filled into a heat-resistant container and placed in the electric furnace, and then fired under the same firing conditions as above. Re-baking can further increase the luminance of the phosphor. Furthermore, when cooling the fired product from the firing temperature to room temperature, the desired stimulable phosphor can also be obtained by taking the fired product out of the electric furnace and allowing it to cool in the air. It is better to cool in a weakly reducing atmosphere or a neutral atmosphere.
The luminance of the obtained photostimulable phosphor due to stimulation can be further increased. In addition, by moving the fired product from the heating section to the cooling section in the electric furnace and rapidly cooling it in a weakly reducing atmosphere or neutral atmosphere, the luminescence brightness due to stimulation of the obtained stimulable phosphor can be further increased. can be increased. In order to obtain the above-mentioned stimulable phosphor raw material mixture as a uniform mixture, it is preferable to prepare this mixture as an aqueous dispersion. In this case, after drying the dispersion, the above-mentioned calcination is carried out. conduct.

The stimulable phosphor obtained after firing is pulverized, and then processed by various operations generally employed in the production of phosphors, such as washing, drying, sieving, etc., to produce the stimulable phosphor according to the present invention. 6 The average particle diameter of the stimulable phosphor used in the radiation green image conversion panel 13 of the present invention is usually that of the radiation image conversion panel 1
Considering the sensitivity and granularity of 3, the average particle size is 0.1 to 10.
017 m as appropriate.

More preferably, those having an average particle diameter of 1 to 30 Jjl are acceptable.

In the radiation image conversion panel 13 of the present invention, the stimulable phosphor of the present invention is generally dispersed in a suitable binder and coated on a support. Examples of binders include proteins such as gelatin, polysaccharides such as dextran, or gum arabic, polyvinyl butyral,
Polyvinyl acetate, nitrocellulose, ethylcellulose, vinylidene chloride-vinyl chloride copolymer, polymenal methacrylate), [vinyl chloride-vinyl acetate cobo IJ mer, polyurethane, cellulose acetate butyrate, polyvinyl alcohol, etc.] are commonly used for layer formation. A binder is used.

Generally, the binder is used in an amount of 0.0% per part by weight of the stimulable phosphor.
It is used in a range of 0.01 to 1 part by weight. However, in terms of sensitivity and sharpness of the radiation image conversion panel 13 obtained, it is preferable to use less binder, and it is easier to apply.
The range of 0.03 to 0.2 parts by weight is more preferable based on the balance.

Furthermore, in the radiation image conversion panel 13 of the present invention,
Generally, a protective layer for physically or chemically protecting the stimulable phosphor layer is provided on the surface exposed to the outside of the stimulable phosphor layer (the surface not hidden by the bottom of the phosphor layer substrate). . This protective layer may be formed by directly applying a protective layer coating liquid onto the stimulable phosphor layer, or by bonding a separately formed protective layer on the stimulable phosphor layer. It's okay.

As the material for the protective layer, conventional materials for the protective layer such as nitrocellulose, ethylcellulose, cellulose acetate, polyester, polyethylene terephthalate, etc. can be used.

This protective layer is selected to be one that transmits stimulated luminescence light and, when irradiation with excitation light is performed from the protective layer side, transmits excitation light. In addition, the preferred film thickness is about 2~
It is 40-.

Next, an example of a method for manufacturing the radiation image conversion panel 13 will be shown below.

First, pulverized stimulable phosphor powder, a binder, and a solvent are mixed and kneaded into a light beam to prepare a coating liquid in which the stimulable phosphor is uniformly dispersed.

Examples of solvents include lower alcohols such as methanol, ethanol, low alcohol, and n-1 tanol; chlorine-containing hydrocarbons such as methylene chloride and ethylene chloride; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; Examples include lower esters such as methyl acetate, ethyl acetate, and butyl acetate, and ethers such as nooxane, ethylene glycol monomethyl ether, and ethylene glycol monomethyl ether. Note that these solvents may be used in combination.

Furthermore, various useful agents such as a dispersant to supplement the dispersibility of the stimulable phosphor in the coating solution and a plasticizer to ensure the bondability between the binder and the phosphor particles after coating and drying are added. Additives may also be added.

Examples of the dispersant include 7-talic acid, stearic acid, caproic acid, and lipophilic surfactants.

Examples of the plasticizers include phosphoric acid esters such as triphenyl phosphate, tricresyl phosphate, and diphenyl phosphate; heptatalytic esters such as noethyl heptatarate and nomethoxyethyl heptalate; ethyl glycolate; Examples include glycolic acid esters such as tacrylbutyl, and polyethylene glycol-aliphatic dibasic acid polyesters such as triethylene glycol-adipic acid polyester and noethylene glycol-succinic acid polyester.

The coating solution prepared as described above is uniformly applied to a support by a commonly used coating method such as a roll coater method or a blade doctor method to form a stimulable phosphor layer.

Supports used in the present invention include various synthetic resin sheets (for example, sheets of cellulose acetate, polyester, polyethylene terephthalate, polyamide, polyimide, triacetate, polycarbonate, etc.), various metal sheets (for example, sheets of aluminum, aluminum alloy, etc.), and various Examples include paper sheets (for example, sheets of baryta paper, resin coated paper, pigment paper, etc.).

The dry thickness of the stimulable phosphor layer varies depending on the purpose of use of the radiation image conversion panel, the type of stimulable phosphor, the mixing ratio of the binder and the stimulable phosphor, etc., but generally, 10-1000m is suitable, preferably 80m
- to 600-.

Furthermore, in order to increase the sharpness of the image formed on the radiation image conversion panel 13, for example, Japanese Patent Laid-Open No. 55-1464
47, white powder may be dispersed in the stimulable phosphor layer, or JP-A No. 1983-
As described in No. 163500, the sharpness of the image of the fli8 phosphor layer is enhanced by dispersing a colorant that absorbs stimulable excitation light in the stimulable phosphor layer,
It may be appropriately colored in order to absorb the stimulated excitation light.

Furthermore, in order to improve the sharpness and sensitivity of this radiation image conversion panel 13, a light reflecting layer is provided between the support and the stimulable phosphor layer as disclosed in JP-A-56-11393. You can do it like this.

Further, in the radiation image conversion panel of the present invention, a phosphor layer can be formed on the support by vacuum evaporation, sputtering, or the like on the layer obtained by the coating method described above. In this case, a binder is not required, the packing density of the stimulable phosphor can be increased, and a radiation image conversion panel that is preferable in terms of sensitivity and resolution can be obtained.

The phosphor M'X- according to the present invention obtained as described above
aM"X2'・bM"X," ・cA: H4 in dB
An example of the emission spectrum is shown in FIG. The specific composition is as follows.

(a) Csl・0.05BaF2・0. OfΔIF
, -0,058120z", 0.0028a(b)
RbBr・0.05BaFC1・0.0ILaF,
・0.05SiOz”, 0.001TI (c) CsBr ・0.05BaFC1・0,0IY
F, ・0.05SiO□:0.002TI The emission spectrum was measured by irradiating these stimulable phosphors with 80 KVp of Xl/IA and then exciting the phosphors with a semiconductor laser whose oscillation wavelength was 780 nm. be.

Further, FIG. 3 shows the phosphor M'X-aM"X2"-bM"X3" according to the present invention.
c, A: Excitation spectra of dB stimulation are illustrated. 8
The stimulable phosphor (a) irradiated with 0 KVp of X@;
It is a photostimulation excitation spectrum of (b) and (c).

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

Support Example 1 After weighing each photostimulable phosphor raw material as shown in (I) to (I0'') below, they were thoroughly mixed using a ball mill to form a mixture of 10 types of photostimulable phosphor raw materials. I mixed it.

(I) RbBr 165.4g (I mol) BaF2 17.54g (0.1 mol) A
IF3 0.840g (0.01mol)51
02 0.601g (0.01 mol) 11
3r 0.568g (0,002mo)
(2) RbBr 165.4g (I mol) BILF2 17.54g (0.1 mol)
AIFz O, 840g (0.01 mol)
SiO23,0041? (0.05 mol) T18
r O,568g (0,002-T= /
L, )(3) RbBr! 65.4g
(I mol) BaFz 17.54g (0,
1 mol) AIF, 0.840 g (0.01 motk
)SiO□6,009g (0.1mo/L-)T
IBr 06568g (0,002mol)
(4) RbBr 165.4g (I mole) BaF217.54g (0.1 mole) ＾IF, 0.840g (0.01 mole L
, >SiO□ 24.03g (0.4 mol)
TIBr O, 568 g (0,002 mol) (5) CsBr 212.8 g (I
mol) BaCI220,82FK (0.1 mol) YF:
l 1.46g (0.01 mol) ^12
03 1.020g (0.01mol) NaBr
0.206g (0,002mol) (6)
CsBr 212.8g <1 mol) B
aC1220, 82g (0.1 mol) YF, 1.46g
(o, ot mole) ^1203 5.098g
(0.05 mol) NaBr 0.206g
(0,002 mol) (7) CsBr 21
2,8g (I mol) BaC520,82g
(0.1 mol) YF3 1.46g (0
,01 mole)^1□Q, 10.20g (0
, 1 mol) NaBr 0.206g (0,
002 mol) (8) Cs8r 212.8g
(I mol) BaC1220,82g (0,
1 mole) YF3 1,46g
(0,01mo)t; )^1203 40.78g
(0.4 mol) NaBr 0.206g
(0,002 mol) (9) Rh+ 212
．． 4g (I mole) HgF2 62.31g
(0.1 mol) AIFz O, 840g
(0,01 mol) MgO2,016g (0,0
5 mol) EuIz O, 533 g (0,0
01 mol) (I0) Csl 259.8g
(I mole) BaCI2 20,82g (0,
1 mole) LaFs 1.96 g (0,01
mol) TiO□ 3,995g (0.05 mol) Eul, 0.533g (0,001
Mol) Each of the 10 kinds of stimulable phosphor raw material mixtures was packed into a quartz boat and fired in an electric furnace.

Firing is performed using nitrogen gas containing 2% by volume of hydrogen gas at a flow rate of 250.
0cc15? The mixture was heated at 650° C. for 2 hours while flowing with water, and then allowed to cool to room temperature.

After pulverizing the obtained baked product using a ball mill,
The particles were passed through a mesh sieve to make the particle size uniform, and each stimulable phosphor was obtained.

Next, 91 radiation image conversion panels of the present invention were made using the above 10 kinds of stimulable phosphors. Both radiation image conversion panels were manufactured as follows.

Disperse 8 parts by weight of the stimulable phosphor in 1 part by weight of polyvinyl butyral (binder) using a solvent mixed with equal amounts of 77 tons and ethyl acetate. A radiation image conversion panel of the present invention having a film thickness of about 300 nm was prepared by uniformly applying the mixture onto the body) using a wire bar and drying naturally.

These 10 types of radiation image conversion panels of the present invention were installed at a tube voltage of 8°KV at a distance of 1OOCI+ from the X-ray tube focal point.
p, after irradiating X-rays with a tube current of 100 m^ for 0.1 seconds,
This was excited with semiconductor laser light (780 nm, 10 mW), and the fluorescence due to stimulation emitted from the stimulable phosphor layer was measured with a photodetector. The results are shown in Table 1.

Comparative Example 1 In Example 1, the stimulable phosphor raw material was BaF:175.
4g (I mol), BaB r2・2H20333,
3 g (I mol) and C/' E 1120 , 0.3
Stimulable phosphor BaFBr: 0.001 E
I got u. A comparative radiation image conversion panel was prepared in the same manner as in Example 1 using this stimulable phosphor, and the stimulated luminescence brightness was measured using a semiconductor laser (7BOn+s, 10+mW). The results are also listed in Table 1.

Furthermore, in Comparative Example 1, instead of using a semiconductor laser, H
Stimulated luminescence luminance was measured in the same manner as Comparative Example 1 except that an e-Ne laser (633n+*, 10 mW) was used.

The results are also listed in Table 1.

Reference Example 1 Among the photostimulable phosphor raw materials of Samples (I), (5), (9), and (I0) of Example 1, SiO□ and A were added to the above groups, respectively.
Samples (I) and (5) were prepared in the same manner as in Example 1 except that the metal oxide components of I□031Mg0 and TiO2 were removed.
, the following reference sample (I) corresponding to (9) and (I0),
(2), (3) and (4) were created, and the semiconductor laser (7
Stimulated luminescence brightness was measured using a 80 ns, 10 mIA). The results are also listed in Table 1.

Reference sample (I) RbBr・0.1BaF2・0.01^
IF, :0.002TI reference sample (2) CsBr ・
0. lBaCl2・0.01YFz:0.002Na reference sample (3) Rbl・0. IMgFz” 0.0
1^IF*: 0.0OIEu reference sample (4) Csl
・0. lBaCl2・O,0ILaFz:0,001ε
From Table 1, the luminescence brightness due to stimulation of the radiation image conversion panel of the present invention manufactured using the photostimulable phosphors of the samples (I) to (I0) according to the present invention is determined in Comparative Example 1 and Reference Example. 1
This is higher than the luminance due to stimulation measured under the same conditions of each radiation image conversion panel manufactured using a stimulable phosphor other than the present invention, as shown in . The radiographic image conversion method of the invention was more sensitive than the conventional radiographic image conversion method using a comparative radiographic image conversion panel.

By the way, the conventional photostimulable phosphor B taken up in Comparative Example 1
aFBr:Eu has a photostimulation excitation spectrum with a peak wavelength of 6
00 nm, and as an excitation light source, He Ne
Laser light (633nn+) is said to be particularly preferable (Japanese Patent Application Laid-Open No. 15025-1985, etc.). Therefore, BaFBr
: Regarding the comparative radiation image conversion panel manufactured using Eu, the semiconductor laser (780 nm) was replaced with a HeNe laser (633 nm) in the method for measuring stimulated luminance brightness, and the measurements were otherwise made under the same conditions. As shown in Table 1 above, the comparative radiation image conversion panel had lower stimulated luminescence luminance than any of the radiation image conversion panels of the present invention. Therefore, since the radiation image conversion method of the present invention using the radiation image conversion panel of the present invention can use a semiconductor laser as an excitation light source, it can be made smaller than the conventional radiation image conversion method using a He-Ne laser. At the same time, it was highly sensitive.

Example 2 A radiation image conversion panel using the stimulable phosphor of the sample (3) of the present invention prepared in Example 1 and a radiation image conversion panel using the stimulable phosphor of the reference sample (I) were For humidity testing, it was placed in a humidity chamber set at 50° C. and 90% relative humidity. This forced deterioration rate is at least 80 times higher than that at 20° C. and 50% relative humidity found in a typical air-conditioned X-ray room.

Each radiation image conversion panel is taken out periodically,
After irradiating with X-rays in the same manner as in Example 1, it was excited with a semiconductor laser, and the luminescence brightness due to stimulation at that time was measured6.
The stimulable luminance of each radiation image conversion panel before the forced humidity test was set as 100, and the luminance was expressed as relative luminance to that, and the decline in the stimulable luminance over time was compared, and the results were compared in As shown in the figure.

:jS4 Figure shows that the radiation image conversion panel using the photostimulable phosphor of the present invention has better moisture resistance than the reference radiation image conversion panel using the photostimulable phosphor, and the luminance of the stimulated luminescence decreases over time. It became possible to significantly improve the decline.

(Effects of the Invention) As explained above, since the stimulable phosphor according to the present invention has high sensitivity to radiation, when the radiation image conversion method of the present invention is used for X#i diagnosis etc. It becomes possible to reduce the amount of radiation exposure.

Furthermore, the stimulable phosphor according to the present invention has excellent moisture resistance, and it has become possible to greatly improve the decrease in luminance due to stimulation over time.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an outline of a major embodiment of the method of the present invention. :jS2 diagram is the photostimulation excitation spectrum of the example of the stimulable phosphor according to the present invention, and f53 diagram is the photostimulation excitation spectrum of the example of the phosphor. FIG. 4 is a diagram showing the results of a forced humidity test. 11...Radiation generating device 12...Subject 13.
...Radiation image conversion panel 14...Excitation light rj, 15...Photoelectric conversion device 18.
··filter

Claims (1)

[Claims] 1) Radiation transmitted through or emitted from the subject is absorbed by at least one of the photostimulable phosphors represented by the following general formula (I), and then the photostimulable phosphor is A radiation image conversion method characterized by exciting a phosphor with electromagnetic waves selected from visible light and infrared rays to cause the stimulable phosphor to emit radiation energy accumulated in the form of fluorescence, and detecting this fluorescence. General formula (I) M^ I X・a_M^IIX_2'・b_M^IIIX_3
”・c_A:d_B (However, M^ I is Li, Na,
At least one alkali metal selected from K, Rb and Cs. M^II is Be, Mg, Ca, Sr, Ba, Zn, Cd,
It is at least one divalent metal selected from Cu and Ni. M^III is Sc, Y, La, Ce, Pr, Nd
, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er,
It is at least one trivalent metal selected from Tm, Yb, Lu, Al, Ga, and In. X, X' and X'' are at least one kind of halogen selected from F, Cl, Br and I. A is BeO, MgO, CaO, SrO, BaO, ZnO
, Al_2O_3, Y_2O_3, La_2O_3, I
n_2O_3, SiO_2, TiO_2, ZrO_2,
GeO_2, SnO_2, Nb_2O_5, Ta_2O
It is at least one kind of oxide selected from _5 and ThO_2. B is Eu, Tb, Ce, Tm, Dy,
Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y
, Tl, Na, Ag, Cu and Mg. Also, a, b, c, and d are respectively 0≦a<0.5, 0≦b<0.5, 0<c<0.5,
It is a numerical value in the range of 0<d≦0.2. ) 2) b and c in the general formula (I) are each 0≦
The radiation image conversion method according to claim 1, characterized in that b≦10^-^2,0<c≦0.2. 3) M^III in the general formula (I) is Y, La,
Sm, Gd, Lu. 3. The radiation image conversion method according to claim 1 or 2, wherein the material is at least one trivalent metal selected from Al, Ga, and In. 4) X” in the general formula (I) is F, Cl and B
4. The radiation image conversion method according to claim 1, wherein the halogen is at least one kind of halogen selected from r. 5) M^III in the general formula (I) is Be, Mg,
The radiation image conversion method according to any one of claims 1 to 4, characterized in that the material is at least one alkaline earth metal selected from Ca, Sr, and Ba. 6) A in the general formula (I) is MgO, Al_2O
_3, SiO_2, and TiO_2. The radiation image conversion method according to any one of claims 1 to 5. 7) d in the general formula (I) is 10^-^6≦d
The radiation image conversion method according to any one of claims 1 to 6, characterized in that ≦0.1. 8) B in the general formula (I) is Eu, Ce, Sm,
The radiation image conversion method according to any one of claims 1 to 7, characterized in that the material is at least one metal selected from Tl, Ag, Cu, and Na. 9) The radiation image conversion method according to any one of claims 1 to 8, wherein the electromagnetic wave is a laser beam. 10) The radiation image conversion method according to any one of claims 1 to 9, wherein the laser light is a semiconductor laser. 11) In a radiation image conversion panel comprising a support and at least one stimulable phosphor layer provided on the support, at least one of the phosphor layers has the following general formula (
A radiation image conversion panel characterized by containing a phosphor represented by I). General formula (I) M^IX・aM^IIX_2'・bM^IIIX_3"・c
A: dB (However, M^I is at least one kind of alkali metal selected from Li, Na, K, Rb and Cs. M^II is Be, Mg, Ca, Sr, Ba, Zn, Cd,
It is at least one divalent metal selected from Cu and Ni. M^III is Sc, Y, La, Ce, Pr, Nd
, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er,
It is at least one trivalent metal selected from Tm, Yb, Lu, Al, Ga, and In. X, X' and X'' are at least one kind of halogen selected from F, Cl, Br and I. A is BeO, MgO, CaO, SrO, BaO, ZnO
, Al_2O_3, Y_2O_3, La_2O_3, I
n_2O_3, SiO_2, TiO_2, ZrO_2,
GeO_2, SnO_2, Nb_2O_5, Ta_2O
It is at least one metal oxide selected from _5 and ThO_2. B is Eu, Tb, Ce, Tm, Dy,
Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y
, Tl, Na, Ag, Cu and Mg. Also, a, b, c, and d are respectively 0≦a<0.5, 0≦b<0.5, 0<c<0.5,
It is a numerical value in the range of 0<d≦0.2. ) 12) b and c in the general formula (I) are each 0≦
The radiation image conversion panel according to claim 11, characterized in that b≦10^-^2,0<c≦0.2. 13) M^III in the general formula (I) is Y, La
, Sm, Gd, Lu, Al, Ga, and In. 14) The radiation according to any one of claims 11 to 13, wherein X'' in the general formula (I) is at least one kind of halogen selected from F, Cl, and Br. Image conversion panel. 15) M^II in the general formula (I) is Be, Mg,
Claim 1, characterized in that it is at least one kind of alkaline earth metal selected from Ca, Sr, and Ba.
The radiation image conversion panel according to any one of Items 1 to 14. 16) A in the general formula (I) is MgO, Al_2
The radiation image conversion panel according to any one of claims 11 to 15, characterized in that the panel is at least one of O_3, SiO_2, and TiO_2. 17) d in the general formula (I) is 10^-^6≦d
Claim 11, characterized in that ≦0.1.
The radiation image conversion panel according to any one of Items 1 to 16. 18) B in the general formula (I) is Eu, Ce, Sm
, Tl, Ag, Cu, and Na.
The radiation image conversion panel according to any one of Items 1 to 17.