JPS5956479A - Radiation image conversion - Google Patents

Abstract

PURPOSE:To form an image with a good conversion efficiency by exciting with near-IR rays and allowing to emit in near UV rays with the high luminance, by using a particular accumulative phosphor in the radiation image conversion utilizing a stimulative phosphor. CONSTITUTION:By irradiating an object 12 with light from a radiation source 11, a latent image is formed on a radiation image conversion panel 13. Then the fluorescence corresponding to said latent image is produced by light emitted from a light source 14 and displayed through a filter 18, a photoelectric convertor 15, and an image regenerator 16 on an image display device 17. In said method, an accumulative phosphor contg. an Eu<2+>-activated compound halide phosphor of the formula (wherein X, X' are each Cl, Br; x, a are each 0-2) (e.g., BaFBr.10<-3>NaBr:10<-3>Eu<2+>) is used and the latent image formed is excited by light of 450-1,100nm in wavelength.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radiation image conversion method, and more particularly to a radiation image conversion method using a photostimulable phosphor.

Conventionally, a so-called radiographic method has been used to obtain radiographic images using a photographic film having an emulsion layer made of a silver salt photosensitive material and an X-ray intensifying screen. One of the radiographic image conversion methods that can obtain radiographic images with superior image sharpness and resolution.
As one example, U.S. Pat.
Specification No. 36,264, JP-A-55-163472,
The method described in Publication No. 55-116340 and the like is attracting attention.

This radiation image conversion method uses a storage phosphor (a phosphor that emits light when excited with electromagnetic waves selected from visible light and infrared rays after being irradiated with radiation. Here, radiation refers to X-rays, α-rays, β-rays, It uses electromagnetic waves or particle beams such as gamma rays, high-energy neutron beams, electron beams, vacuum ultraviolet rays, and ultraviolet rays.) The radiation that passes through the subject is absorbed by a stimulable phosphor, and then The phosphor is excited with electromagnetic waves selected from visible light and infrared rays, and the radiation energy accumulated in the photostimulable phosphor is emitted as fluorescence (stimulated luminescence), and this fluorescence is detected and imaged. It is something to do.

Conventionally, as a type of fluorohalide phosphor, the following formula, Ba
FX: aEu2+ (However, X is at least one of CJ, Br, and ■, and a is a number that satisfies the condition Q<a≦0.2.) Barium halide phosphors are known. This phosphor emits high-intensity near-ultraviolet light (instantaneous light emission) when excited by X-rays, ultraviolet rays, electron beams, etc., and is used in practical applications, especially as a phosphor for X-ray intensifying screens. This phosphor also exhibits high brightness stimulated luminescence. In other words, this phosphor has a temperature of 45% after being irradiated with radiation.
When excited by electromagnetic waves in the wavelength range of 0 to 1l100n, it emits near-ultraviolet light with high brightness. Therefore, this phosphor can be used in the radiation image conversion method described above (U.S. Pat.
．． 239. 968).

By the way, when the above-mentioned 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 patient's exposure dose. It is desirable that the stimulable phosphor has as high a luminance as possible due to stimulation. From this point of view, it is desired to improve the sensitivity of the radiation image conversion method using the BaFX:Eu2+ phosphor, and therefore, it is desired to improve the luminance of light emission through the stimulation of the BaFX:Eu2+ phosphor. ing.

The present invention was made under the above-mentioned circumstances,
By using a phosphor with higher emission brightness due to stimulation than the BaFX:Eu2+ phosphor as the stimulable phosphor, the radiation sensitivity is higher than that of the radiation image conversion method using the BaFX:Eu2+ phosphor. The purpose of this invention is to provide an image conversion method.

In order to achieve the above object, the present inventors have developed BaFX:Eu
Various studies have been conducted on improving the luminance of 2+ phosphors through photostimulation. As a result, BaFX: barium fluoride halide (13a F
X) and sodium halide (NaX', where X' is at least one of C7!, Br, and ■)
A complex halide consisting of is used as a matrix, and this matrix is
The new fluorophore activated with valent europium emits near-ultraviolet light with higher brightness than the conventional BaFX:Eu2+ fluorophore when excited by electromagnetic waves in the wavelength range of 450 to 1l100n after being irradiated with radiation. The present invention was completed based on the discovery that the following is true.

The radiation image conversion method of the present invention has the following formula: BaFX -xNaX' : aEu2+ (where X and X' are both at least one of CI, Br and I, and X and a are each 0<x≦ 2
and 0<a≦0.2) A stimulable phosphor containing a divalent europium-activated composite halide phosphor is made to absorb the radiation transmitted through the subject, and then After that, add 450 to 1l100 of this phosphor.
It is characterized in that the phosphor is excited by electromagnetic waves in the wavelength range of n to emit the radiation energy accumulated in the phosphor as fluorescence, and then the phosphor is detected.

The divalent europium-activated composite halide phosphor used in the radiation image conversion method of the present invention is a conventional BaFX
:EuZ+ Similar to fluorophores, it emits near-ultraviolet light when excited by electromagnetic waves in the wavelength range of 450 to 1l100n after being irradiated with radiation such as X-rays, but the brightness of the emitted light due to this stimulation is lower than that of BaFX:Eu2+ Higher than phosphor.

Therefore, the radiation image conversion method of the present invention is based on BaFX:Eu2+
It is more sensitive than radiation image conversion methods that use fluorophores. In addition, among the above divalent europium-activated composite halide phosphors, the X value of the above formula is 10-5≦X≦5X10
A phosphor having an X value in the range of -1 has a particularly high luminance due to photostimulation, and therefore the radiation image conversion method of the present invention using a phosphor having an X value in this range has particularly high sensitivity. Also, Na
Of X', NaI and NaBr are particularly preferable because they provide particularly high emission brightness due to stimulation, and furthermore, NaI can reduce the degree to which the accumulated radiation energy decreases over time before excitation (hereinafter referred to as fading).

Further, the preferable range of a value in the above formula is 10-5≦a≦10
-1.

The present invention will be explained in detail below.

The divalent europium-activated composite halide phosphor used in the radiation image conversion method of the present invention is manufactured, for example, by the manufacturing method described below.

First, the phosphor raw materials are 1) barium fluoride (B a F2 ), ii) barium chloride (B a Cj! 2), barium bromide (BaB
r2) and barium iodide (BaI2), iii) at least one of sodium chloride (NaCj2), sodium bromide (NaBr) and sodium iodide (NaI), and iv) a halide. Compounds of trivalent europium such as , oxides, nitrates, and sulfates are used. Using these four phosphor raw materials, a phosphor raw material stoichiometrically represented by the formula BaFX-xNaX': aEu'' (where x, x', X and a have the same meanings as above) A mixture is prepared.The phosphor raw material mixture may be prepared by simply mixing the above four phosphor raw materials, or the BaF
It may be prepared by first generating BaFX using the barium halide described in 2 and ii) above, and then mixing this BaFX with the sodium halide described in iti) above and the activator raw material in iv) described above. In the latter phosphor raw material mixture preparation method, B a F2
Various known methods can be employed to generate BaFX from barium halide. For example, BaFX can be easily produced by mixing BaF2 and barium halide and heating the resulting mixture at a temperature of 100°C or higher for several hours (dry method,
1-28591). Also, BaFX is made into a suspension of BaF2.

Add a solution of barium halide, preferably under reduced pressure.
It can also be easily produced by stirring while heating and gradually evaporating water to dryness (wet method, see JP-A-51-61499).

In both the dry method and the wet method, by interposing the activator raw material in the reaction system, uniform mixing of BaFX and the activator raw material can be achieved simultaneously with the production of BaFX. In any method for preparing a phosphor raw material mixture, BaF2, barium halide, sodium halide and activator raw material, or BaFX
, sodium halide, and activator raw materials are thoroughly mixed. Mixing is performed using a conventional mixer such as a mortar, ball mill, or rondo mill.

Next, the obtained phosphor raw material mixture is filled into a heat-resistant container such as a quartz boat, an alumina crucible, or a quartz crucible, and fired in an electric furnace. A suitable firing temperature is 600 to 1000°C. The firing time varies depending on the filling amount of the phosphor raw material mixture, the firing temperature, etc., but generally 1 to 6 hours is appropriate. A weakly reducing atmosphere such as a nitrogen gas atmosphere containing a small amount of hydrogen gas or a carbon dioxide atmosphere containing a small amount of carbon monoxide is used as the firing atmosphere, thereby reducing trivalent europium to divalent europium during the firing process. . After firing once under the above firing conditions, the fired product is taken out of the electric furnace, left to cool, and pulverized.The fired product powder is then filled into a heat-resistant container again, placed in the electric furnace, and fired under the same firing conditions as above. Re-firing may be performed. In this case, a neutral atmosphere such as a nitrogen gas atmosphere or an argon gas atmosphere may be used instead of the weakly reducing atmosphere as the firing atmosphere. After firing, the resulting fired product is loosened, and the sieved material is processed by various operations commonly employed in the production of homofluorescent materials to obtain the phosphor of the present invention.

The following formula obtained by the manufacturing method explained above, Ba
FX −xNa X / : a E1
12+ (However, X and X' are both at least one of C7!, Br, and ■, and X and a are numbers that satisfy the conditions O<X≦2 and Q<a≦0.2, respectively. The divalent europium-activated composite halide phosphor represented by When excited, it emits near-ultraviolet light.

And the luminance of light emission due to the exhaustion is BaFX:Eu2+
Higher than phosphor. Therefore, the radiation image conversion method of the present invention using this phosphor has higher sensitivity than the radiation image conversion method using the BaFX:Eu2+ phosphor. Figure 1 illustrates the excitation spectrum of the divalent europium-activated composite halide phosphor used in the radiation image conversion method of the present invention. BaFBr measured using -10-"NaBr: 10-"Bu2
+ This is the excitation spectrum of the fluorophore. As is clear from Fig. 1, BaFBr ・10-'NaBr: 10''
The excitation wavelength range of Eu2+ fluorophore is 450 to 1l.
100 nm, and especially 450 to 750 nm is the optimum excitation wavelength range. The excitable wavelength range of the divalent europium-activated composite halide phosphor used in the radiation image conversion method of the present invention varies slightly depending on the composition of the phosphor, but is generally as shown in FIG. The optimum excitation wavelength range is 450 to 1l100n, which is almost the same as the result obtained above, and the optimum excitation wavelength range is 450 to 750nm.

In this range, the phosphor can be excited without substantially increasing its temperature. The excitable wavelength range and the optimum excitation wavelength range approximately correspond to the excitable wavelength range and the optimum excitation wavelength range of the BaFX:Bu2+ fluorophore.

FIG. 2 illustrates the emission spectrum due to stimulation of the divalent europium-activated composite halide phosphor used in the radiation image conversion method of the present invention.
r ・10-'NaBr: 10-'EuZ+ After irradiating the phosphor with X-rays with a tube voltage of 80 KVp, the phosphor was
This is an emission spectrum measured by excitation with e-Ne laser light (633 nm). Although it varies somewhat depending on the composition of the phosphor, the divalent europium-activated composite halide phosphor used in the radiation image conversion method of the present invention emits near-ultraviolet light as shown in Figure 2 through photostimulation. shows. The emission spectrum due to stimulation of the composite halide phosphor is almost the same as the emission spectrum due to stimulation of the BaFX:Eu2+ phosphor.

Figures 3 and 4 are BaFBr-xN''B, respectively.
r: 10-'Eu2+Eu2+fluorescence Ba FC7
!・xNaBr: 10-'Eu2+Eu2+After irradiating X-rays with a fluorescence pressure of 80KVp, the fluorophores were exposed to He
- It is a graph showing the relationship between the amount X value of NaBr0 (horizontal axis), which is a matrix component of the phosphor, and the luminescence luminance due to photostimulation (vertical axis) when excited with a Ne laser (633 nm). The vertical axis of the figure is expressed as a relative value when the emission brightness due to stimulation of BaFBr: 10-3Eu2 + phosphor is taken as 100, and the vertical axis of Fig. 4 is BaFC#: 10-3Eu.
It is expressed as a relative value when the emission brightness due to exhaustion of the 2+ phosphor is set to 100. As is clear from FIG. 3 and FIG. 4, BaFBr-xNaBr used in the radiation image conversion method of the present invention whose X value is in the range of Q<x≦2:
10-″Eu2+Eu2+fluorescent BaFCjl -xNa
B r: 10-'Eu2+Eu2+fluorescence, each of which has an X value of 0 B a FB r: 10-'Eu2+E
u2+ fluorescent BaFCβ: exhibits stimulated luminescence with higher brightness than to-3Eu2+ fluorescent material. Also, BaFBr-xNaBr
:10-'Euz+fluorophore and BaFC# xNa
Even in the case of Br: 10-'Eu2+Eu2+fluorescence, a phosphor having an X value in the range of 10-5≦X≦5X10-1 has particularly high luminance. In addition, FIGS. 3 and 4 respectively show BaFBr-xNaBr:10-'Eu2+Eu
2+fluorescent BaFCjl -xNaBr: 10-'E
This shows the relationship between the X value of u2+Eu2+fluorescence and the luminescence brightness due to photostimulation.
Z + fluorophore Ba FC/ -xNa I: 10-'
Regarding the EuZ+ phosphor, the relationship between the X value and the emission brightness due to photostimulation was almost the same as in FIGS. 3 and 4, respectively. Also BBaFBr-xNacjl: 1 0
-”Eu2+, BaFCjl-xNacll:10'
``''E uZ + The relationship between the X value of the phosphor and the luminescence luminance due to stimulation is that the curves in Figure 3 or 4 are not convex upwards, but the luminance stimulated luminance is from 10-' to 2. An improved relationship is shown. Furthermore, both Figs. 3 and 4 show Eu2+i
This shows the relationship between the X value and the luminescence brightness due to photostimulation for a phosphor with an la value of 10-3, but it also shows the relationship between the X value and the luminescence brightness due to photostimulation for a phosphor whose a value has changed. It was confirmed that the relationship is similar to that shown in FIGS. 3 and 4.

The radiation image conversion method of the present invention will be specifically explained using schematic diagrams. In FIG. 5, 11 is a radiation generating device, 12 is a subject, 13 is a radiation image conversion panel having a stimulable phosphor layer containing the divalent europium-activated composite halide phosphor, and 14 is the radiation image. A light source as an excitation source for emitting the latent radiation image accumulated in the radiation image conversion panel as fluorescence; 15 is a photoelectric conversion device for detecting the fluorescence emitted from the radiation image conversion panel; 16 is a photoelectric conversion device for detecting the fluorescence emitted from the radiation image conversion panel; 17 is a device for displaying the reproduced image; 18 is a device for canting the reflected light from the light source 14 and transmitting only the light emitted from the radiation image conversion panel 13; This is a filter that allows you to From 15 onwards, it is sufficient that the optical information from 13 can be reproduced as an image in some form, and is not limited to the above.

As shown in FIG. 5, 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 according to changes in radiation transmittance. 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 panel 13, thereby generating a number of electrons or holes proportional to the absorbed radiation dose in the phosphor layer, which accumulates. It accumulates at the trap level of the fluorophore. That is, an accumulated image (a kind of latent image) of radiation dose 5 is formed. This latent image is then excited with light energy to become visible.

That is, the excitation light emitted from the light source 14 scans the stimulable phosphor of the radiation image conversion panel 13 to expel the electrons or holes accumulated at the trap level, causing the accumulated image to be emitted as fluorescing. As mentioned above, the excitable wavelength range of the divalent europium-activated composite halide phosphor used in the stimulable phosphor layer of the radiation image conversion panel 3 is 450 to 1l100n, and the optimum excitation wavelength is The range is 4
Since the wavelength is 50 to 750 nm, the excitation light is 450 nm.
〜1l100n.

Preferably, electromagnetic waves having a wavelength of 450 to 750 nm are used. In this range (450 to 750 nm), the stimulable phosphor layer can be excited without substantially increasing its temperature, so deterioration of the phosphor and phosphor layer due to temperature changes can be prevented.

The intensity of the fluorescence emitted from the stimulable phosphor layer due to excitation by the excitation light is determined by the number of accumulated electrons or holes, that is, the radiation energy absorbed by the stimulable phosphor layer of the radiation image conversion panel 13. This optical signal is converted into an electrical signal by a photoelectric conversion device 15 such as a photomultiplier tube, reproduced as an image by an image reproducing device 16, and this image is displayed by an image display device 17.

The radiation image conversion panel used in the radiation image conversion method of the present invention has a stimulable phosphor layer containing the divalent europium-activated composite halide phosphor dispersed in a suitable binder. If the stimulable phosphor layer is self-supporting, the stimulable phosphor layer itself can serve as a radiation image storage panel, but generally the stimulable phosphor layer is provided on a suitable support. A radiation image conversion panel is constructed. Furthermore, a protective film is usually provided on one side of the stimulable phosphor layer (the side opposite to the side on which the support is provided) for physically or chemically protecting the phosphor layer. Further, an undercoat layer may be provided between the phosphor layer and the support for the purpose of more closely adhering the stimulable phosphor layer and the support. Note that the radiation image conversion method panel having the above structure may be colored with a coloring agent as disclosed in JP-A-55-163500 (the stimulable phosphor layer is colored). In some cases, it is preferable that the degree of coloring is gradually increased from the excitation light incident side to the opposite side).
X': aEu2÷In addition to the phosphor, a stimulable phosphor that emits light by stimulation with electromagnetic waves in the wavelength range of 450 to 1l100n among known stimulable phosphors may be used in combination, if desired. . Preferred known stimulable phosphors to be used in combination include the rare earth activated lanthanum oxyhalide phosphor described in JP-A-55-12144, and U.S. Pat. No. 4,2
No. 36.078, JP-A-55-12143, JP-A-55-12143
No. 12145, No. 55-84389, No. 56-238
Examples include rare earth-activated alkaline earth metal fluorohalide phosphors described in No. 5, No. 56-2386, and No. 56-74175.

In addition, in the stimulable phosphor layer of the radiation image conversion panel,
A white powder may be dispersed as disclosed in No. 5-146447. Furthermore, the radiation image conversion panel has a metal reflective layer on the side opposite to the excitation light incident side of the stimulable phosphor layer, as disclosed in JP-A No. 56-11393 or 8 JP-A-56-12600. Alternatively, a white pigment reflective layer may be provided. By using colorants or white powder in this way,
Further, by providing a light reflecting layer, a radiation image conversion panel that provides images with high sharpness can be obtained.

In the radiation image conversion method of the present invention, the light source for the light energy that excites the stimulable phosphor layer of the radiation image conversion panel may be other than a light source that emits light with a banded spectral distribution in the wavelength range of 450 to 1l100n. niHe-N
e laser light (633 nm), YAG laser light (10
A light source that emits light of a single wavelength is used, such as a ruby laser beam (64 nm), a ruby laser beam (694 nm), or an argon laser beam (488 nm).

Particularly when using laser light, high excitation energy can be obtained. Among laser beams, especially He-Ne
More preferably, laser light is used.

As explained above, the divalent europium-activated composite halogen 9-ride phosphor used in the radiation image conversion method of the present invention has higher emission brightness due to stimulation than the conventional BaFX:Bu2+ phosphor. Therefore, the radiation image conversion method of the present invention has higher sensitivity than the radiation image conversion method using only BaFX:Eu2+ fluorophore.

Next, the present invention will be explained by examples.

Example 1゜BaF2175.5g (1 mol), BaBr2297
, Ig (1 mol), NaBr0.206g (2×1
01 mol) and EuBr3 o, 783 g (2XI
0-3 mol) was weighed out and thoroughly mixed using a ball mill. The obtained phosphor raw material mixture was filled into a quartz boat, placed in a tube furnace, and fired. Firing was performed at 900° C. for 2 hours while flowing nitrogen gas containing 1% by volume of hydrogen gas at a flow rate of 280 cc/min.

After firing, the quartz boat was taken out of the tube furnace and allowed to cool to room temperature. After the obtained fired product was pulverized using a ball mill, the fired product powder was again filled into a quartz boat and placed in a tube furnace for secondary firing. The secondary firing was performed at 700° C. for 1 hour while flowing nitrogen gas at a flow rate of 280 cc/min. After the secondary firing, the quartz boat 0 was taken out from the tube furnace and allowed to cool to room temperature, and the resulting fired product was loosened and passed through a sieve. In this way, BaFB
An r-10'-'NaBr:10-'Eu2+ phosphor was obtained.

Also, instead of NaBr, 10,117 g of NaC (2X
10-” mol) and 10.30 g Na (2X10-
BaFBrlO-'NaCj! :10-"Euz÷fluorophore and BaFBr・10-"NaI: 10
-3 E u2 ÷ phosphor was produced. Furthermore, BaFBr・1 was prepared in the same manner as above except that NaBr was not used.
A 0″3Eu2+ phosphor was produced.

Next, a radiation image storage panel was manufactured using the four types of phosphors described above. Both radiation image storage panels were manufactured as follows.

First, 8 parts by weight of the phosphor and 1 part by weight of nitrified cotton (binder) were mixed using a solvent (mixture of acetone, ethyl acetate, and butyl acetate) to prepare a coating solution having a viscosity of about 50 centistokes. Next, this coating solution was uniformly coated on a horizontally placed polyethylene terephthalate film 1 (support), and left to dry naturally day and night to form a phosphor layer with a layer thickness of about 300 μm,
It was used as a radiation image conversion panel.

Next, the luminescence brightness due to stimulation of the four types of radiation image conversion panels obtained was measured. To measure the luminance due to this stimulation, the radiation image conversion panel is irradiated with X-rays with a tube voltage of 80 KVp, and then excited with He-No laser light (633 nm), and the fluorescent light emitted from the phosphor layer is measured. This was carried out by receiving light with a photoreceiver (photomultiplier tube with spectral sensitivity S-5).

BaFBr・10-'NaBr: 10-"Eu2+fluorophore, BaFBr・10-"NaCj2: 10-
Both of the radiation image conversion panels using jEu2+ phosphor and BaFBr/10-'NaI phosphor have luminance due to stimulation that is about twice that of the radiation image conversion panel using 13aFBr:10-'EuZ+ phosphor. Met. The detailed numerical values are shown in Table 1 below. Therefore, the radiation image conversion method of the present invention using these radiation image conversion panels is based on BaFB.
r: approximately 22 times more sensitive than a radiation image conversion method using a radiation image conversion panel using only 10-'Eu2+ phosphors.

Example 2 Ba F2 175. 3 g (1
mole), BaC#220B, 2g (1!mol), Na
Cj! 0.117 g (2xlO-3 mol) and Eu
7BaFCj210-' N
aCJ: A 10"" E u 2+ fluorophore was produced. NaCj again! NaBr0.206g (2X
10-' mol) and Na I O, 30 g (2X
BaFCl -10-'Na B r : 1 in the same manner as above except that 10-'%
0-'Eu2+Eu2+fluorescent BaFCIl・10-"N
aI: A 10-'Bu2+ fluorophore was produced. Zarani NaC7! A BaFCIl:lO-''Eu2+ phosphor was produced in the same manner as above except that BaFCIl:lO-''Eu2+ was not used.

Next, a radiation image conversion panel was manufactured in the same manner as in Example 1 using the obtained 4Na phosphor. Then obtained 4
The emission brightness due to stimulation of each type of radiation image conversion panel was measured in the same manner as in Example 1.

3 BaFC# ・10-”NaCj!: 10-’Eu
2+Eu2+fluorescent FCIl ・10-'NaBr:
10-'Eu2+Eu2+fluorescent Ba FCJ -10-
'Nar: 10-' Euz
FCIl: Slightly more than twice that of a radiation image conversion panel using a 10-''Eu2+ phosphor.

The detailed numerical values are shown in Table 1 below. Therefore, the radiation image conversion method of the present invention using these radiation image conversion panels is more than twice as sensitive as the radiation image conversion method using a radiation image conversion panel using BaFCIl: 10-'Eu2+Eu2+fluorescence.

Example 3 61.7 g (0.6 mol) of NaBr, 24
7.0 g (2,4 mol) and 493.9 g (4,
BaF was prepared in the same manner as in Example 1 except that BaF
Br ・0.3NaBr: 10-'EuZ+fluorophore, BaFBrl, 2NaBr: 10-'Eu2+Eu2
+ Fluorescent BaFBr -2,4NaBr: 10-'E
(12+ phosphors were produced.

Next, radiation image conversion panels were manufactured in the same manner as in Examples 1 and 4 using the three types of phosphors obtained. Thereafter, the luminescence brightness due to stimulation of the three types of radiation image conversion panels obtained was measured in the same manner as in Example 1.

As shown in Table 1 below, BaFBr・0°3Na
Br: 10-'Eu2+Eu2+fluorescent BaFBr・
The radiation image conversion panel using 1.2 NaBr: 10-'Eu2+Eu2+ fluorescein has a luminance due to stimulation that is about 1.2% compared to the radiation image conversion panel using BaFBr:lO-''Eu2+ phosphor of Example 1. 7 times and approx.
．． BaF had twice as much, but more Na B ril.
Br・2.4NaBr: l O−'Eu2+Eu2
The emission brightness due to photostimulation of the +fluorescent radiation image conversion panel was about 0.7 times that of the radiation image conversion panel using the BaFBr:10-"Eu2+ phosphor of Example 1. Therefore, the BaFBr.0. 3NaBr: 1O-3Eu2+ fluorophore and Ba FB r ・1. 2Na Br :
The radiation image conversion method of the present invention using a radiation image conversion panel using a 10-3Eu2+ phosphor is BaFBr!
10-” compared to a radiation image conversion method using a radiation image conversion panel using only a Eu needle tip light body, each approximately 1.7
BaFBr2.4NaBr:1O
-3F, u2+2+ A radiation image conversion method using a radiation image conversion panel using fluorescence is BaFBr:1O-3EuE
The sensitivity is about 30% lower than that of a radiation image conversion method using a radiation image conversion panel using only a u light body.

6 Table 1 27

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 respectively show BaFBr・10""NaBr:1O used in the radiation image conversion method of the present invention.
-3Bu2+ fluorophore excitation spectrum and stimulable bed emission spectrum. Figures 3 and 4 show BaFBr-xNaBr:1O-
3Eu2+ and BaFCIl-xNaBr: 10
-3 It is a graph showing the relationship between the NaBr amount X value in the Eu needle tip light body and the luminescence luminance due to photostimulation. FIG. 5 is a schematic explanatory diagram of the radiation image conversion method of the present invention. 11...-Radiation generating device, 12...-Subject, 13.
-Radiation image conversion panel, 14--Light source, 15--Photoelectric conversion device, 16--Image reproduction device, 17--Image display device, 18--Filter. Patent applicant: Fuji Photo Film Co., Ltd. 8 Four strategies or loss is deafening

Claims (1)

[Claims] At least one of the following formula % formula % summer, where X and a are numbers satisfying the conditions 0<x≦2 and Q<a≦0.2, respectively) The radiation transmitted through the object is absorbed by a storage phosphor containing a divalent europium-activated composite halide phosphor, and then this phosphor is
1. A radiation image conversion method characterized in that a phosphor is excited by electromagnetic waves in a wavelength range of n to emit accumulated radiation energy as fluorescence, and this fluorescence is detected.