JPS6172089A - 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 electromagentic wave, and detecting the emitting 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 (Rb and/or Cs are essential); 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 Tl, Na, Ag or Cu; 0<=a<=1; 0<=b<=0.5; 0<c<=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 Field of Application) The present invention relates to a radiation image conversion method and a radiation image conversion panel used in the method, more particularly a radiation image conversion method using a stimulable phosphor and the method. The present invention relates to a radiation image conversion panel used for.

(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 phosphor emits the accumulated radiation energy as fluorescence. Therefore, methods of detecting this fluorescence and creating images are being considered. 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 thermofluorescent phosphor layer formed on a support, and the thermofluorescent phosphor layer of this panel absorbs the radiation that has passed through the subject, accumulating radiation energy corresponding to the intensity of the radiation. Then, by heating this thermofluorescent phosphor layer, the accumulated radiation energy is extracted as a light signal, and an image is obtained by varying the intensity of this light. However, since this method heats the accumulated radiation energy when converting it into a light 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 using a panel in which a stimulable phosphor layer is formed on a support and using visible light and/or infrared rays as excitation energy is also known (US Pat. No. 3,895,
No. 527). Unlike the above method, this method does not require heating when converting MhL radiation energy into a light signal, so the panel does not need to be heat resistant.
From this point of view, this method can be said to be a more preferable radiation image conversion method.

Conventional thermofluorescent phosphors include L iF :Mg tB
aSo4:MntCaFz:Dy and the like are known. Further, as a stimulable phosphor using visible light or infrared rays as excitation energy, KCI:TI or B aF
:Eu'' type (X:C1tBr,I) phosphors and the like are known.

By the way, when the radiation image conversion method is used for X-ray image conversion for the purpose of medical diagnosis, it is desirable that the method be as sensitive as possible in order to reduce the radiation dose to the patient. It is desirable that the stimulable phosphor has the highest possible luminance 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 must have a short response speed of stimulated luminescence to excitation light. Faster is better.

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 t48 type phosphor is 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 image be small, low-cost, and simple;
For this purpose, it is impractical to use a semiconductor laser as an excitation light source rather than using a slave such as an Ar laser or a He-Ne laser, and therefore the stimulable phosphor used in this method is (750n1 or more)
It is desirable to have a photostimulated excitation spectrum suitable for

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.

(Object of the invention) The present invention allows radiation transmitted through an object to be absorbed into a stimulable phosphor, and then the stimulable phosphor is absorbed by visible light and/or
Alternatively, in a radiation image conversion method in which the stimulable phosphor is excited by electromagnetic waves in the infrared range to emit the accumulated radiation energy as fluorescence and detect this fluorescence, it exhibits stimulated luminescence with higher brightness. The purpose of the present invention is to provide a highly sensitive radiation image conversion method using a stimulable phosphor.

Another object of the present invention is to provide a radiation image conversion method that allows high-speed reading using a TirA stimulable fluorescent phosphor that exhibits a fast response speed of stimulated luminescence to excitation light.

Another object of the present invention is to provide a radiation image conversion method that uses a stimulable phosphor that can be repeatedly used and has a high afterimage erasing speed and that has a short afterimage erasing time.

A further object of the present invention is to provide a radiation image conversion method in which a semiconductor laser can be used as an excitation light source using a stimulable phosphor whose stimulable excitation spectrum extends to the near-infrared region.

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 conducted various studies on stimulable phosphors that exhibit high-intensity stimulated luminescence and whose stimulated excitation spectrum extends to the near-infrared region. A stimulable phosphor containing an alkali halide phosphor represented by the following general formula ([) is made to absorb radiation transmitted through or emitted from an object, and then this phosphor is selected from visible light and infrared rays. The present invention can be achieved by a radiation image conversion method characterized in that a phosphor is excited by an electromagnetic wave to emit the accumulated radiation energy as fluorescence, and this fluorescence is detected, and by a radiation image conversion panel that satisfies the above requirements. The purpose is achieved.

General formula (1) %Formula %: However, Mr is at least one kind of alkali metal selected from LiwNa, Rb and Cs, and includes at least either Rb or Cs. M” is BewMgyC
at least one divalent metal selected from a, Sr, Ba, Zn, CdtCu and N1; M+= is Sc;
Y, La, Ce, Pr, Nd, Pm, 51Eu, Gd,
Tb.

At least one trivalent metal selected from DytHotEr, Tm, Yb, Lu, ALGa and In,
X.

X' and x'' are at least one kind of halogen selected from F, CI, Br and I, and A is T1.Na.

At least one metal of A g + Cu. Further, a is a numerical value in the range of O≦a≦1, and b is a numerical value in the range of O≦b≦0.
C is a numerical value in the range of 0<c≦0.2.

That is, the stimulable phosphor having the composition according to the present invention exhibits stimulated luminescence with higher brightness than conventionally known stimulable phosphors when excited by electromagnetic waves in the visible to infrared region, and therefore exhibits stimulated luminescence in the near-infrared region. A radiation image conversion method with high sensitivity for practical use can be obtained in the near future.

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

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 image conversion method of the present invention provides a radiation image conversion panel consisting essentially of a support and at least one IQi stimulable phosphor layer containing a stimulable phosphor provided on the support. The method is carried out using a radiation image conversion panel in which at least one of the stimulable phosphor layers contains a stimulable phosphor represented by the general formula (1).

After absorbing radiation such as X-rays, the stimulable phosphor of the general formula (1) absorbs radiation in the visible or infrared region, preferably 5
When irradiated with light (excitation light) in the wavelength range of 00 to 900 nm, it exhibits stimulated luminescence. Therefore, the radiation transmitted through the subject or emitted from the subject is absorbed by the stimulable phosphor contained in the stimulable phosphor layer of the radiation image conversion panel in proportion to the amount of radiation i, and the radiation image is A subject or a radiation image of the subject is formed on the conversion panel as a latent image in which radiation energy is accumulated. When this latent image is excited with excitation light in a wavelength range of 500 nm or more, it shows stimulated luminescence that is proportional to the accumulated radiation energy, and by reading this stimulated luminescence in a charged manner, it is possible to accumulate radiation energy. It becomes possible to turn the latent image into a visible image.

The present invention will be explained in detail below.

The tjS1 diagram shows the response characteristics to excitation light of the stimulable phosphor represented by the general formula (1) used in the radiation image conversion method of the present invention compared to the stimulable phosphor used in the conventional method. Compare and show.

In the fpJJ diagram, (,) is the response characteristic to excitation light of the photostimulable phosphor used in the radiation image conversion method of the present invention, (b) and V (c) is the response characteristic of the photostimulable phosphor used in the conventional method. Phosphor BaFBr:Eu and IBaFCl
: Response characteristics of Eu. Moreover, the broken line shows the state of the excitation light whose intensity changes in a rectangular shape.

As is clear from FIG. 1, the stimulable phosphor used in the radiation image conversion method of the present invention has extremely excellent response characteristics to excitation light, and the radiation image reading speed is faster than that of the conventional method. It is possible to increase the speed.

FIG. 2 shows the afterimage erasing characteristics of the stimulable phosphor represented by the general formula (1) used in the radiation image conversion method of the present invention in comparison with that of the stimulable phosphor used in the conventional method.

In FIG. 2, (cl) is '?' when the stimulable phosphor used in the radiation image conversion method of the present invention is irradiated with a certain amount of radiation and then the stored energy is erased with tungsten lamp light. I is the attenuation characteristic of product energy, (e) and (
) is the stimulable phosphor BaFBr used in the conventional method.
:Eu and BaFCI: This is the attenuation characteristic of I product energy when Eu is measured in the same manner as above.

As is clear from FIG. 2, the stimulable phosphor used in the radiation image conversion method of the present invention produces accumulated energy (afterimage).
The decay rate is high, and the time required to erase afterimages can be shortened compared to conventional methods.

FIG. 3 schematically shows an embodiment example in which the stimulable phosphor represented by the general formula (1) is used in the form of a radiation image conversion panel in the radiation image conversion method of the present invention.

In FIG. 3, 11 is a radiation generating device, 12 is a subject,
13 is a radiation image conversion panel having a visible or infrared light stimulable phosphor layer containing the X1lI stimulable phosphor represented by the general formula (1); 14 is a radiation latent image of the radiation image conversion panel An excitation light source for emitting fluorescence, 15 a photoelectric conversion device for detecting the fluorescence emitted from the radiation image conversion panel 13, 16 a device for reproducing the charge conversion signal detected by the photoelectric conversion device 15 as an image, 1
7 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 the fjS3 diagram is an example of obtaining a radiographic image of a subject, if the subject 12 itself emits radiation (subject), the radiation generating device 11 is not particularly necessary. Further, the photoelectric conversion device 15 and subsequent devices may be any device that can reproduce optical information from the panel 13 as an image in some form, and are not limited to the above. As shown in FIG. 3, when the subject 12 is placed between the radiation generating device 11 and the radiation green image conversion panel 13 and irradiated with radiation, the radiation passes through each part of the subject 12 as the radiation transmittance changes. A 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 A panel 13, and a number of electrons and/or holes proportional to the amount of radiation absorbed in the stimulable phosphor layer are thereby generated. This is accumulated at the trap level of the stimulable phosphor.

That is, a latent image is formed in which the energy of the radiographic image is accumulated. This latent image is then excited with light energy to become visible. That is, the light source 14 that emits light in the visible or infrared region generates t4/? - The phosphor layer is irradiated to drive out the electrons and/or genuine bills accumulated at the trap level, and the accumulated energy is released as fluorescence. The intensity of this emitted fluorescence is determined by the accumulated electrons and/or
Alternatively, it is proportional to the number of genuine bills, that is, the strength of the radiation energy absorbed by the stimulable phosphor layer of the radiation image conversion panel 13, and this optical signal is converted into an electrical signal by a photoelectric conversion device 15 such as a photomultiplier tube. image processing device 16
The image is reproduced as an image by the image display device 17, and this image is displayed by the image display device 17. 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 light of the excitation light and the fluorescence emitted from the stimulable phosphor layer, and the photoelectric converter that receives the fluorescence emitted from the stimulable phosphor layer generally has a short wavelength of less than Boons. It is desirable that the fluorescence emitted from the stimulable phosphor layer has a spectral distribution in as short a wavelength region as possible because the sensitivity to the potential energy of the stimulable phosphor layer increases.

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

That is, the flt-exhaustive fluorescence used in the present invention all exhibits light emission having a main peak below 500 nm, is easily separated from the excitation light, and matches well with the spectral sensitivity of the photoreceiver, so that it can be efficiently used. As a result of being able to receive light, the sensitivity of the image receiving system can be increased.

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 second harmonic, ruby laser, semiconductor laser, various dye lasers, and metal vapor lasers such as copper vapor laser. Normally, a continuous wave laser such as a He-Ne laser or an Ar ion laser is preferable, but the panel 1
A pulsed laser can also be used if the pixel scanning time and pulse are synchronized. 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 particularly preferred because they are small, inexpensive, and do not require a modulator.

The filter 18 transmits the stimulated luminescence emitted from the radiation image conversion panel 13 and filters out the excitation light. It is determined by the combination of the wavelength and the wavelength of the excitation light source 14.

For example, in the case of a preferable combination for χ, such as a photostimulated excitation wavelength of 500 to 900 nm and a stimulated emission wavelength of 300 to 5001 nm, the filter may be, for example, Toshiba C-
39, C-40, V-40, V-42, V-44, Konink 7-54.7-59, Spectrofilm! BG-1, BG-3, BG-25, BG-37゜BG
A purple to blue color lass filter such as -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.

The photoelectric conversion device 15 includes a phototube, a photomultiplier tube, 7
Any device capable of converting a change in light amount into a change in an electrical signal may be used, such as an otodiode, an ototransistor, a solar cell, or a photoconductive element.

Next, a radiation image conversion panel used in the radiation #1IlIi 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 111II stimulable phosphor layer containing a stimulable phosphor represented by the general formula (1) provided on the support. configured.

In the photostimulable phosphor represented by the general formula <1), from the viewpoint of stimulated luminance, M' in the general formula (1) is
, L i , Na, K = at least one kind of alkali metal selected from Rb and Cs; at least Rh,
It is preferable that either one of Cs is included.

As Ml, BetMg, Ca5Sr and VBa
Preferably, at least one alkaline earth metal selected from Y, LatSm, GdvLu, t
AI.

At least one trivalent metal selected from Ga and In is preferred. X” is preferably at least one type of halogen selected from F, CI and Br.MIII
The b value representing the content of X3'' is preferably selected from the range of 0≦b≦10-2.

The C value representing the amount of activator is selected from the range of 10-'≦C≦0.1 based on the stimulated luminescence brightness. ! , preferred.

Stimulable phosphor M'X-aM''X2 according to the present invention
'・bMIIX,'': cA is produced, for example, by the production method described below.

Insect photostimulable phosphor raw materials include: 1) LiF, LiC1, Liar, Lil
, NaF, NaCl, NaBr.

Nal, KF, KCI, KBr, NiI, RbF
, RbC1, RbBr.

Rbl, CsF, CsC1, CsBr, two or more types of Csl, ■) BeF2+ BeC12v BeBr2+
Be12. MgF2+ MgCIztMgB
r2+ MgLt CaFz+ CaC1□t C
aBr2v Ca12+5rFzySrCI□, 5
r8r2. Sr [z, RoaF2t BaCIz
-BaBr2+BaBr2 * 2LL Ba1z+
ZnF2t ZnCl2. ZnBr2+Zn[zv
CdFz-CdC1z-CdBr=, CdL, CuFz
-CuClz, CuBrx.

Cul, NiF2. N1Ch, N1Brz, N
It seems that there are two or more types of i12) 5CF3. SCC+3.5cBrr,
5cl=,yp,,YCI,,YBr,.

YI knee LaF, -LaC1=, LaBr1l
La1), CeF,, Cel*+CeB
r)+ Cel, PrFz, PrCl5+ Pr
Br,, Pr13. NdF3゜NdC1x, NdBr
z, Nd1i, PmF:+-PmC1=, PmBr5
゜Pm13+ SmFnt SmC1n, S Br=, SII+3- EuF=, EuCl,.

EuBr== Eu1s+ cdF3. Gdcl,,
GdBr1t GdllgTbFz.

rbc13. TbBr1+ Tbl:+* DyFi
+ DyCl1. DyBr: +tDyl*+11oFs
, HoC1)t HoBrt, 1Io13. ErF)
+ErC1, -ErBr3. Erl,,v TmF
, , TmC1z, TmBr3. Tml,,YbF,.

YbCl3. YbBr1. Yb1i-LuFzt L
uCI), LuBrz.

Lu13- ＾IF1. ^ICI,, ^1Brz
e ^lli, cdF3tcac13゜Gd8rcw
Gd+, InFz-1nCIt, InBrxt
lnl, and IV) TI compound group, Ha compound group, Heg compound group, C
One or more types of activator raw materials from the u compound group are used.

MIX-aMIIX2′・bMIIXff#: stoichiometrically represented by general formula (1): in CA, 0≦a≦1, O≦b≦0.5, preferably O≦b
≦to-”, 0<c≦0.2 preferably 10-6≦C≦
The above-mentioned stimulable phosphor raw materials I) to (iv) are weighed so that the mixed composition is 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 can be a weakly reducing atmosphere such as a nitrogen atmosphere containing a small amount of hydrogen, a carbon dioxide atmosphere containing a small amount of carbon monoxide, or a neutral atmosphere such as a nitrogen atmosphere or an argon atmosphere. is preferred. In addition, 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, placed in the electric furnace, and re-fired under the same firing conditions as above. If this is done, the luminance of the phosphor can be further increased. 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 neutral atmosphere rather than a weakly reducing 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.

The stimulable phosphor of the present invention is obtained by pulverizing the stimulable phosphor obtained after firing, and then processing it through various procedures generally employed in the production of phosphors, such as washing, drying, and sieving. get.

The average particle diameter of the stimulable phosphor used in the radiation image conversion panel 13 of the present invention is usually
Considering the sensitivity and granularity of 3, the average particle size is 0.1 to 1.
It is appropriately selected within the range of 00-.

More preferably, particles having an average particle diameter of 1 to 30 mm are used.

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 applied to 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 polymer, polymethyl methacrylate, vinyl chloride-vinyl acetate polymer,
Binders commonly used for layer formation are used, such as polyurethane, cellulose acetate butyrate, polyvinyl alcohol, and the like.

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 the sensitivity and sharpness of the radiation image conversion panel 13 obtained, it is preferable to use a smaller amount of the binder, and from the viewpoint of ease of application, the range of 0.03 to 0.2 parts by weight is more preferable. preferable.

Furthermore, in the radiation green 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 a-retaining layer may be formed by directly applying a protective layer coating liquid onto the stimulable phosphor layer, or by adhering a separately formed protective layer on the stimulable phosphor layer. You may.

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

It should be noted that this protective J1 scrap 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. The preferred film thickness is approximately 2
~40Jra.

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

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

The solvent includes methanol, ethanol, n-7''
Lower alcohols such as alcohol, n-butyl, chlorine-containing hydrocarbons such as methylene chloride and ethylene chloride, acetone, methyl ethyl ketone, methyl imbutyl ketone, methyl acetate, ethyl acetate, butyl acetate and ethers such as nooxane, ethylene glycol more ethyl ether, and ethylene glycol more ethyl 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, triprenol phosphate, and diphenyl phosphate; heptatarate esters such as diethyl heptatarate and nomethoxyethyl heptatarate; ethyl glycolate; 7 tallylethyl glycolate; butyl glycolate; Examples include glycolic acid esters such as tacryl butyl, and polyethylene glycol-aliphatic dibasic acid polyesters such as triethylene glycol-7 dipic acid polyester and diethylene glycol-succinic acid polyester.

The coating liquid 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 green radiation image conversion panel, the type of stimulable phosphor, the mixing ratio of the binder and the stimulable phosphor, etc., but in general, , 10- to 1000jjI, preferably 80- to 600-.

Furthermore, in order to improve the sharpness of the image formed on the radiation image conversion panel 13, for example, Japanese Patent Application Laid-Open No. 55-146
447, white powder may be dispersed in the stimulable phosphor layer, or as described in JP-A No. 55
- As described in No. 163500, the sharpness of the image of the stimulable phosphor layer is increased by dispersing a coloring agent that absorbs the 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 green image conversion panel 13, a light reflecting layer is provided between the support and the 1lifi-exhaustive phosphor as disclosed in Japanese Patent Application Laid-Open No. 11393/1983. You can do it like this.

Further, in the radiation image conversion panel of the present invention, in addition to being obtained by the above-mentioned coating method, a phosphor layer can be obtained on a support by a vacuum evaporation method, a sputtering method, or the like. In this case, a binder is not required, the packing density of the tij-exhaustive phosphor can be increased, and radiation #i is preferable in terms of sensitivity and resolution.
An image conversion panel is obtained.

The phosphor M'X- according to the present invention obtained as described above
The emission spectra of 14 aM"X2'.bM"X,":cA are illustrated in FIG. 4. The specific compositions are as follows.

(a) Csl -0,05BaF2 @ 0,
018lF3:0.002Na(b) RbBr ・0
．． 0ICsF ・0.05BaFCI ・0. Old aF
): 0.0OITl (c) CsBr ・0,05BaFGl ・0.01Y
Ft: 0.002TI 80KVp for these stimulable phosphors
After irradiating the phosphor with X-rays, the phosphor has an oscillation wavelength of 780 nm.
This is an emission spectrum measured by excitation with a semiconductor laser.

Further, FIG. 5 shows the phosphor M'X-aM "X:'・bM'X-" according to the present invention:
The excitation spectrum of cA stimulation is illustrated. 80KVp
The above t4-exhaustive phosphor (a), (b) irradiated with X-rays of
and (e) are the photostimulated excitation spectra.

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

Example 1 After weighing the stimulable phosphor raw materials as shown in (1) to (16) below, they were thoroughly mixed using a ball mill to obtain 1
Six types of stimulable phosphor raw material mixtures were prepared.

(1) RbBr 160.4g (0,
97 mol) CsF 4.56g (0.03 mol)rlBr O,0568g (0.0O02
mole) (2) RbBr 160.4g
(0.97 mol) CsF 4.56 g (
0,0:L-+: TIBr 0.568g
(0,002 mol) (3) RbBr 1
60.4g (0.97mol) CsF
4.56g (0.03mol) Ding Jar 5
．． 68g (0.02 mol) (4) RbBr
165.4g (1 mol) BaF217.54g
(0.1 mol) 8IFs O, 840g
(0.01 mol) TIBr O, 568g
(0,002 mol) (5) RbBr 157
．． 1g (0.95 mol) CsF 7.6
0g (0.05 mol) BaFz 17.5
4g (0.1 mol) Alh 0.840g
(0,01 mol)■1□0 0,424g
(0,001 mol) (6) RbBr 165.
4g (1 mol) BaF2 17.54g
(0.1 mol) Alh 0.840g (0
,01 mol) TIBr 0.568g (0
,002mol)Hair O,0412g(0
,0004 mol) (7) Rb1 212.4g
(1 mol) MgFz 6.23g (
0.1 mol) LaF v 1.96 g (
0.01 mol) 8g I O, 470g (
0,002 mol) (8) CsF 151.9
g (1 mol) TIF 0.447g
(0,002 mol) (9) CsBr 212.
8g (1 mol) NaBr 0.0206
g (0,0002 mol) (10) CsBr
212.8g (1 mol) NaBr 0.
206g (0,002mol) (11) CsBr
212.8g (1 mol) NaBr
2:06g (0.02mol) (12) CsBr
2t2.8g (1 mol) BaC1220,
82g (0.1 mol) YF, 1.46
g (0.01 mol) NaBr 0.20
6g (0,002 mol) (13) CsBr
202.2g (0.95 mol) Rbl
to, 62g (0.05 mol) [)acI2
20.82g (0.1 mol) YF31.46
g (0.01 mol) NaBr 0.20
6g (0,002 mol) (14) CsBr
208.5g (0.98 mol) Rbl
4,25g (0,02 mol) TIBr 0
．． 568g (0,002 mol) (15) Csl
259.8g (1 mol) [3aF217
,54g (0,1 mol)YCL 1,9
53g (0.01 mol)'Ma1 0.3
00g (0,002 mol) (16) Csl
259.8g (1 mol) BaF2 1
7.54g (0.1 mol) YCl, 1
．． 953g (0.01 mol)Cul 0
．． 381 g (0,002 mol) Next, each of the 16 types of l:iIP exhaustible phosphor raw material mixtures was packed into a quartz boat and fired in an electric furnace. Firing was carried out at 650° C. for 2 hours while flowing nitrogen gas containing 2% by volume of hydrogen at a flow rate of 2500 cc/min, and then allowed to cool to room temperature.

After pulverizing the obtained baked product using a ball mill,
The particles were sieved through a 0-mesh sieve to make the particle size uniform, and each stimulable phosphor was obtained.

Next, a radiation image conversion panel of the present invention was manufactured using the 16 types of stimulable phosphors. Both radiation image conversion panels were manufactured as follows.

First, 8 parts by weight of the stimulable phosphor were dispersed in 1 part by weight of polyvinyl butyral (binder) using a solvent containing equal parts of acetane and ethyl acetate, and this was placed horizontally on a polyethylene terephthalate film (supporting A radiation image conversion panel of the present invention having a film thickness of approximately 300 mm was prepared by uniformly applying the mixture onto the body) using a wire bar and drying naturally.

These 16 types of radiation image conversion panels of the present invention are
Tube voltage 80KV at a distance of 1100C from the tube focus
p, after 0.1 seconds of irradiation with xi with a tube current of 100 mA,
This is a semiconductor laser beam (780nm, 10n+W)
The fluorescent light emitted from the stimulable phosphor layer was measured using a photodetector. The results are shown in Table 1.

Comparative Example 1 In Example 1, the stimulable phosphor raw material was BaF:175.
4g (1 mol), B aB rz ・2H20333
, 3g (1 mol) and E u20 , 0.352g
A stimulable phosphor BaFBr: 0.001 Eu was obtained in the same manner as in Example 1 except that the amount was changed to (0,001 mol). Using this stimulable phosphor, a comparative emission green image conversion panel was produced in the same manner as in Example 1, and a semiconductor laser (
Stimulated luminescence brightness was measured using 780 nm, 10 mW). The results are also listed in Table 1.

Comparative Example 2 Instead of using a semiconductor laser in Comparative Example 1, He
Stimulated luminescence luminance was measured in the same manner as Comparative Example 1 except that a Ne laser (633n, 10mW) was used.

Table 1 [- 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 (1) to (16) according to the present invention is as follows: The emission brightness i) above the photostimulation measured under the same conditions of the comparative radiation image conversion panel manufactured using the conventional photostimulable phosphor BaFBr:Eu shown in 1) is also higher, and therefore, the radiation image of the present invention The radiation image conversion method of the present invention using a conversion panel was more sensitive than the conventional radiation image conversion method using a comparative radiation 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 (633 nm) is said to be particularly preferable (Japanese Patent Application Laid-Open No. 15025-1985, etc.), so BaF
Regarding the comparative radiation image conversion panel manufactured using Br:Eu, the semiconductor laser (780 nm) was changed to a He-Ne laser (633 nm) in the XiI & exhaustive luminescence luminance method, and measurements were made under the same conditions except for that. This is shown in Table 1 as Comparative Example 2, but the comparative radiation image conversion panel had lower stimulated 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,
This method can be made smaller and has higher sensitivity than the conventional radiation image conversion method using a He-Ne laser.

Example 2 After irradiating the radiation image conversion panel of the present invention using the stimulable phosphor (5) prepared in Example 1 with X-rays in the same manner as in Example 1, excitation light whose intensity changes in a rectangular shape He as
A Ne laser was irradiated for 10 μsee, and changes in the brightness of stimulated luminescence emitted from the stimulable phosphor layer were measured using a photodetector. The time required for the brightness of stimulated luminescence to change from 10% to 90% was determined as the response speed of the stimulable phosphor to excitation light and is shown in Table 2.

Comparative Example 3 Radiographic image conversion panel (5) of the present invention in Example 2
The response speed was determined in the same manner as in Example 2, except that the comparative radiation image conversion panel prepared in Comparative Example 1 was used instead of using.

Table 2 From Table 2, the response speed of the stimulable phosphor according to the present invention is about 3 times faster than that of the comparative stimulable phosphor, and the radiation image conversion method using the stimulable phosphor according to the present invention Compared to when using stimulable phosphor, the reading speed of radiographic images in
It is possible to make it twice as fast.

Example 3 After irradiating the radiation image conversion panel of the present invention used in Example 2 with xi in the same manner as in Example 1, the stored energy was erased for 10 seconds using a 10,000 lux halogen lamp. Next, this was excited with a He Ne laser (10 mW), and the luminance of stimulated luminescence emitted from the stimulable phosphor layer was measured using a photodetector. The measurement results are shown in Table 3, with the stimulated luminescence brightness before erasure using a halogen lamp being 1.

Comparative Example 4 In Example 3, the stimulated luminescence luminance was measured in the same manner as in Example 3, except that the comparative radiation image conversion panel prepared in Comparative Example 1 was used instead of the radiation image conversion panel of the present invention. . The measurement results are the same as in Example 3. Table 3 shows that the stimulable phosphor of the present invention has less stored energy (afterimage) than the comparative stimulable phosphor. Erasing speed is about 4
It is twice as fast, and it is possible to reduce the afterimage erasing time in the radiation image conversion method using the 1114-based phosphor according to the present invention to 1/4 compared to when using a comparative stimulable phosphor.

(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-ray diagnosis etc. It becomes possible to reduce the amount of radiation exposure.

In addition, since the stimulable phosphor according to the present invention has a fast response speed to excitation light and a fast erasing speed of stored energy (afterglow), the radiation image reading speed in the radiation image conversion method of the present invention can be increased, and the afterimage erasing time can be increased. It is possible to improve the operating efficiency of the system by shortening the time.

Furthermore, since the stimulable excitation spectrum of the stimulable phosphor according to the present invention extends to the oscillation wavelength region of a semiconductor laser, it can be excited by a semiconductor laser, resulting in miniaturization and low cost of radiation image reading devices. It is possible to simplify and simplify the process.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the response characteristics of a photostimulable phosphor. Further, FIG. 2 is a diagram showing the afterimage erasing characteristics of the stimulable phosphor. FIG. 3 is an explanatory diagram showing an outline of an embodiment of the method of the present invention. FIG. 4 shows the stimulated emission spectrum of an example of the stimulable phosphor according to the present invention, and FIG. 5 shows the stimulated excitation spectrum of the example of the phosphor. 11...Radiation generating device 12...Subject 13.
...Radiation image conversion panel 14...Excitation light source 15...Photoelectric conversion device 18...Filter agent Patent attorney No. 1) Tokichiya-in-law

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 (However, M^ I is Li, Na, K, Rb
and Cs, and includes at least either Rb or Cs. M^II is Be, Mg, Ca, Sr, Ba, Zn, Cd,
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, E r
, Tm, Yb, Lu, Al, Ga and In, X, X' and X'' are at least one halogen selected from FCl, Br and I, and A is At least one metal of Tl, Na, Ag, and Cu.Also, a is a numerical value in the range of 0≦a≦1, b is a numerical value in the range of 0≦b≦0.5, and c is 0. <A numerical value in the range of c≦0.2.) 2) b in the general formula (I) is 0≦b≦10＾-
The radiation image conversion method according to claim 1, characterized in that ^2. 3) M^III in the general formula (I) is Y, La,
3. The radiation image conversion method according to claim 1, wherein the material is at least one trivalent metal selected from SmGd, Lu, Al, Ga, and In. 4) The radiation image conversion method according to claims 1 to 3, wherein x'' in the general formula (I) is at least one type of halogen selected from F, Cl, and Br. ) M^II in the general formula (I) is Be, Mg,
5. The radiation image conversion method according to claim 1, wherein the material is at least one alkaline earth metal selected from Ca, Sr, and Ba. 6) c in the general formula (I) is 10^-^6≦c≦
The radiation image conversion method according to any one of claims 1 to 5, characterized in that the ratio is 0.1. 7) The radiation image conversion method according to any one of claims 1 to 6, wherein the electromagnetic wave is a laser beam. 8) The radiation image conversion method according to any one of claims 1 to 7, wherein the laser beam is a semiconductor laser. 9) 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"
:cA (However, M^I is at least one kind of alkali metal selected from Li, Na, K, Rb and Cs, and includes at least one of Rb and Cs. M^II is Be, Mg, Ca, Sr , Ba, Zn, Cd
, Cu and Ni, and M^III is Sc, Y, La, Ce, Pr,
Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, E
r, Tm, Yb, Lu, Al, Ga and In, and X, X' and X'' are at least one halogen selected from F, Cl, Br and I; A is at least one metal of Tl, Na, Ag, and Cu. Also, a is a numerical value in the range of 0≦a≦1, b is a numerical value in the range of 0≦b≦0.5, and c is a numerical value in the range of 0<c≦0.2.) 10) b in the general formula (I) is 0≦b≦10^-
The radiation image conversion panel according to claim 9, characterized in that the radiation image conversion panel is ^2. 11) M^III in the general formula (I) is Y, L
The radiation image conversion panel according to claim 9 or 10, characterized in that it is at least one trivalent metal selected from a, Sm, Gd, Lu, Al, Ga, and In. 12) The radiation image conversion panel according to claims 9 to 11, wherein x'' in the general formula (I) is at least one type of halogen selected from F, Cl, and Br. ) M^II in the general formula (I) is Be, Mg
13. The radiation image conversion panel according to claim 9, wherein the radiation image conversion panel is at least one kind of alkaline earth metal selected from , Ca, Sr, and Ba. 14) c in the general formula (1) is 10^-^5≦c
The radiation image conversion panel according to any one of claims 9 to 13, characterized in that ≦0.1.