JPS62133399A - Radiation picture conversion panel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a radiation image conversion panel using a photostimulable phosphor. This invention relates to a radiation image conversion panel that provides an image.

(Prior Art) Radiographic images such as X-ray drawings are often used for disease diagnosis. In order to obtain this X-ray image, the X-rays that have passed through the subject are irradiated onto the fluorescent screen of the VT light main body layer.
This generates visible light, which is then irradiated onto a film using silver salt to develop it in the same way as when taking ordinary photographs, which is what is called radiography. However, in recent years, methods have been devised to directly extract images from the phosphor layer without using a film coated with silver salt.

This method involves making a phosphor absorb the radiation that has passed through the object, and then exciting the phosphor with, for example, light or thermal energy, so that the phosphor releases the radiation energy accumulated through the absorption. There is a method of emitting it as light, detecting this fluorescent light, and creating an image. Specifically, for example, U.S. Pat.
No. 5-12144 discloses a radiation image conversion method using a photostimulable phosphor and using visible light or infrared rays as an 11-excitation source. This method uses a radiation image conversion panel in which a layer of photostimulable fluorophore is formed on a support, and radiation transmitted through the object is applied to the photostimulable phosphor layer of this radiation image conversion panel. A latent image is formed by transmitting radiation energy corresponding to the radiation transmittance of each part of the subject, and then this stimulable phosphor layer is scanned with g1+excitation light to detect the accumulated radiation energy of each part. It radiates radiation energy, converts it into light, and obtains an image using an optical signal based on the intensity of this light. This final image may be reproduced as a hard copy or on a CRT.

Now, the radiation image conversion panel having a stimulable phosphor layer used in this radiation image conversion method has a radiation absorption rate and a light conversion rate (both of which are It goes without saying that the radiation sensitivity (hereinafter referred to as "radiation sensitivity") is high, and the image graininess is good.
Moreover, high sharpness is required.

However, radiation image conversion panels having a photostimulable phosphor layer are generally prepared by coating and drying a dispersion containing a photostimulable phosphor and an organic binder on a support or protective layer. , the packing density of the photostimulable phosphor is low (filling rate 50%),
In order to sufficiently increase the radiation sensitivity, it was necessary to increase the thickness of the stimulable phosphor layer.

On the other hand, in the radiation image conversion method, the image sharpness tends to be higher as the thickness of the photostimulable phosphor layer of the radiation image conversion panel becomes thinner. It was necessary to thin the exhaustible phosphor layer.

In addition, the granularity of the image in the radiation image conversion method is caused by local fluctuations in the number of radiation quanta (quantum mottorno or structural disturbances in the stimulable phosphor layer of the radiation image conversion panel).
Since it is determined by the structure mottle 2, etc., when the layer thickness of the photostimulable phosphor layer decreases, the number of single radiation particles absorbed by the photostimulable phosphor layer decreases, and the a-child mottle increases IJn. Otherwise, structural disturbances become apparent and t14 mottles increase, resulting in a decrease in image quality. Therefore, in order to improve the graininess of the image, the thickness of the stimulable phosphor layer had to be 17 mm.

That is, as mentioned above, in conventional radiation image conversion panels, sensitivity to radiation, image graininess, and image sharpness tend to be completely opposite to each other with respect to the layer thickness of the stimulable phosphor layer. , the radiation image conversion panels have been made with a certain degree of mutual trade-off between sensitivity to radiation, graininess, and sharpness.

In other words, in conventional radiation image conversion panels, the sharpness of the image rapidly decreases as the thickness of the photostimulable phosphor layer increases due to the large scattering and diffusion of the photostimulable excitation light by the photostimulable phosphor particles, resulting in a decrease in sensitivity. Even if there are some bad points in sharpness, it is difficult to find good points in both sharpness.

By the way, it is well known that the sharpness of the image "↑" in conventional radiography is determined by the spread of instantaneous light emission (light emission during radiation irradiation) of the phosphor in the fluorescent screen. The sharpness of the image in the radiation image conversion method using the above-mentioned photostimulable phosphor is not determined by the spread of the photostimulable fluorescein 1 or 2 in the radiation image conversion panel; It is not determined by the spread of the luminescence of the phosphor as in photography, but depends on the spread of the stimulated excitation light within the panel. Since the radiographic image information stored in the panel is retrieved in a time-series manner, it is preferable that the stimulated luminescence due to the stimulated excitation light irradiated at a certain time (tl) is all illuminated, and the stimulated excitation light is irradiated at a time when all the light is illuminated. However, if the stimulated excitation light spreads within the panel due to scattering etc. and exists outside the irradiated pixel (xi, yi). This is because if the photostimulable phosphor is also excited, the output from the pixel (xl, yl) will be recorded from an area wider than that pixel.Therefore, for a certain period of time (
Stimulated luminescence due to the stimulated excitation light irradiated at time (tl) is transmitted to the pixel (xl) on the panel that was truly irradiated with the stimulated excitation light at that time (tl).

If only the light is emitted from yi), no matter how widespread the light is, it will not affect the sharpness or contrast of the image obtained.

Under these circumstances, several methods have been attempted to improve the above-mentioned drawbacks of radiation image conversion panels having a stimulable phosphor layer formed by dispersing a stimulable phosphor in a binder. There is.

For example, JP-A-56-126QO discloses a method of providing a white pigment light-reflecting layer on one side of a photostimulable phosphor layer formed by dispersing a photostimulable phosphor in a binder. There is. According to this method, by changing the portion of the photostimulable phosphor layer that enters the inside of the vll-injectable phosphor layer from the incident side surface of the photostimulable excitation light into a white pigment light-reflecting layer, the photostimulable phosphor layer The layer thickness of the phosphor layer can be made thinner, which makes it possible to suppress the spread of photostimulable excitation light within the stimulable phosphor layer, resulting in highly sharp radiation images. It is something.

However, in this method, a part of the photostimulable phosphor layer, which is made by dispersing a photostimulable phosphor, which is a type of white pigment, in a binder,
It is simply replaced with a white pigment light-reflecting layer made by dispersing a white pigment in a binder. Therefore, although this method has the effect of suppressing the spread (scattering) of the photostimulable excitation light within the layer by reducing the thickness of the photostimulable phosphor layer, the white pigment light reflects while scattering within the layer. The photostimulated excitation light that reaches the layer is diffusely reflected on the surface of the white pigment light-reflecting layer, or is scattered inside the white pigment light-reflecting layer and reflected toward the photostimulable phosphor layer, and is reflected within the photostimulable phosphor layer. Since the stimulable phosphor is scattered again and the stimulable phosphor is excited over a wide range, the sharpness of the image is not improved much.

In addition, in JP-A-56-11393, the above-mentioned JP-A-56-11393
A method of providing a metal light-reflecting layer in place of the white pigment light-reflecting layer disclosed in No. 12600 is disclosed. According to this method, the portion of the 11+ exhaustible phosphor layer that enters the interior from the surface on the incident side of the photostimulable excitation light is changed into a light reflecting layer. 1 of the phosphor layer
The layer thickness can be made thinner, thereby making it possible to suppress the spread of the fii11-exciting source within the fii11-exciting fluorescent layer, resulting in a radiographic image with high sharpness.

However, this method can also reduce the thickness of the photostimulable phosphor layer and effectively control the spread (scattering) of the photostimulable excitation source within the layer. Since the reaching stimulated excitation light has almost no directivity, it is reflected according to the incident angle of the stimulated excitation light with respect to the metal reflective layer and returns to the stimulated phosphor layer, Since the light scatters again and excites the stimulable fluorophore over a wide area, the sharpness of the image is not improved much.

As mentioned above, the reciprocity between sensitivity to radiation and image sharpness in conventional radiation image conversion panels has hardly been improved, and improvement thereof has been strongly desired.

(Object of the Invention) The present invention has been made in view of the above-mentioned drawbacks of radiation image information panels using photostimulable phosphors, and the purpose of the present invention is to convert radiation images with the same radiation sensitivity. An object of the present invention is to provide a radiation image conversion panel that provides images with higher sharpness than conventional radiation image conversion panels when the panel is made sharper.

Another object of the present invention is to provide a radiation image conversion panel that has higher sensitivity to radiation than conventional radiation image conversion panels when comparing radiation image conversion panels with the same sharpness.

(Structure of the Invention) As described above, the sharpness of the image of the radiation image conversion panel is controlled by the scattering of the photostimulable excitation light within the photostimulable phosphor layer.

According to the research conducted by the present nF1 researchers, in order to improve the sharpness of images without reducing the sensitivity to radiation, it is necessary to increase the stimulation excitation light and/or the bj1 excitation light emission within the photostimulable phosphor layer. It has been found that a combination of both improving the properties and reducing the thickness of the stimulable phosphor layer by providing a light-reflecting layer is extremely effective.

Based on the above findings, an object of the present invention is to provide a radiation image conversion panel having a III-stimulable phosphor layer, in which the stimulable phosphor layer is bonded to form a phosphor. The present invention is achieved by a radiation image conversion panel comprising: a radiation image conversion panel having a light reflecting layer on the interface side of one of the stimulable phosphor layers;

As an aspect of the present invention, the phosphor having a shape formed by sliding the photostimulable phosphor layer has striae in the layer thickness direction, and stimulates stimulation light and stimulated luminescence. It is preferable that directionality be given to the directionality.

Further, the radiation image conversion panel is colored on the incident side of the stimulated excitation light rather than the light reflection layer, and the average reflection of light in the wavelength region of the stimulated excitation light transmitted through the stimulated phosphor layer is The reflectance may be smaller than the average reflectance for light in the same stimulated emission wavelength region.

Further, it is practically preferable that the layer structure is laminated in the following order: support, light reflection layer, and one photostimulable phosphor layer.

Further, the light reflecting layer preferably has an average reflectance of 50% or more for light in the respective wavelength regions of stimulated excitation light and/or ul-stimulated emission, and has a smooth interface whose refractive index optically varies. A layer having a ceramic surface, for example a full surface, is used.

Next, the present invention will be explained in detail.

In the present invention, a single layer of photostimulable phosphor is provided with a phosphor having a shape formed by bonding, and further striae, that is, non-uniform refractive index, is formed in the thickness direction of the layer. In general, a photostimulable phosphor is formed by a vapor phase deposition method in order to provide directivity of stimulated luminescence in the layer thickness direction by adding a portion such as a tortoise-like surface, a gap, etc. This is achieved by

Figure 1 fa) shows a stimulable phosphor layer formed by bonding by vapor deposition, one of the vapor deposition methods, and consisting of fine granular crystals aggregated with gaps and cracks as striae in the layer thickness direction. A cross-sectional electron micrograph is shown, and Δ(b) schematically shows the original directivity III in the layer, that is, the light guiding effect of the layer.

In Figure rb), due to the light guiding effect of each Toru<:III Fl-like crystal IILI+a2+a,..., the stimulated excitation light 11 or stimulated luminescence 12 is repeatedly totally reflected at the crystal interface. ) in the layer thickness direction. the result,
The photostimulable excitation light 11 incident on the radiation image conversion panel is not scattered in the photostimulable phosphor layer 13 and spread, and the directivity is improved. Similarly, the directivity of the directional light 12 is also improved.

As the vapor phase deposition R1 method of the stimulable phosphor, a vapor deposition method, a sputtering method, an ion blating method, etc. can be used.

In the first vapor deposition method, the support is first placed in a vapor deposition apparatus, and then the apparatus is evacuated to a temperature of 10-'Torr.
The degree of vacuum should be approximately Next, at least one of the photostimulable phosphors is heated and evaporated by a method such as resistance heating, evaporation, or an electron beam method to deposit the photostimulable phosphor to a desired thickness on the surface of the nrI support. .

As a result, a stimulable phosphor layer containing no binder is formed, but it is also possible to form one layer of stimulable phosphor in several steps in the vapor deposition step.

Further, in the vapor deposition step, codeposition can be performed using one or more resistance heaters or an electron beam.

After the vapor deposition is completed, a protective layer is provided on the side opposite to the 'b11-exhaustive phosphor layer 12, if necessary, to produce the radiation image conversion panel of the present invention.

Incidentally, after forming the stimulable phosphor layer on the protective layer, the support may be provided.

In addition, in the vapor deposition method, the desired photostimulable phosphor is synthesized on the support by co-evaporating all of the photostimulable phosphor raw materials using a resistance heating type or an electron beam. It is also possible to form a stimulable phosphor layer at the same time.

Furthermore, in the vapor deposition method, the object to be vapor deposited (support or protective layer) may be cooled or heated as necessary during vapor deposition. Alternatively, the vapor-deposited at r m hp exhaustible phosphor layer may be heated. Further, in the vapor deposition method, reactive vapor deposition may be performed by introducing gases such as O, H, etc. as necessary.

In the second method, sputtering, the support is placed in a sputtering device, similar to the vapor deposition method, and then the inside of the device is evacuated to a vacuum level of about IQ Torr. Introducing an inactive gas such as Ar or No into the sputtering equipment
The gas pressure is about Torr.

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

In the sputtering process, it is also possible to form the photostimulable phosphor layer in multiple steps as in the vapor deposition method, and it is also possible to form the photostimulable phosphor layers in multiple steps, as well as to form multiple targets each made of a different photostimulable phosphor. It is also possible to form a stimulable phosphor layer by sputtering the target simultaneously or sequentially using a stimulable phosphor layer.

After sputtering is completed, the radiation image conversion panel of the present invention is manufactured by providing a protective layer on the side of the stimulable phosphor layer opposite to the supporting body side, if necessary, in the same manner as in the vapor deposition method. Incidentally, after forming the stimulable phosphor layer on the protective layer, the support may be provided on a plain surface.

In the above-mentioned sputtering method, multiple and modified 1id stimulable phosphor raw materials are used as targets, and these are sputtered simultaneously or sequentially to synthesize the desired stimulable phosphor on a support and at the same time It is also possible to form a fluorescent phosphor layer. In addition, in the sputtering method, reactive sputtering may be performed by introducing a gas such as 0, 2 H, etc. as necessary.

Furthermore, in the sputtering method, the object to be deposited (the support or the protective layer) may be cooled or heated as necessary during sputtering.

Further, the stimulable phosphor layer may be heat-treated after sputtering.

The third method is the OVD method. Moreover, there is an ion blating method as a fourth method.

Layer of stimulable phosphor layer of radiation image conversion panel of the present invention]
ry varies depending on the radiation sensitivity of the target radiation image conversion panel, the type of photostimulable phosphor, etc., but is 30
Preferably selected from the range of μm to 1000 μm,
More preferably, it is selected from the range of 40 μm to BOO71+7+.

If the layer thickness of the photostimulable phosphor layer is less than 30 μm, the radiation absorption rate will be extremely reduced, the radiation sensitivity will deteriorate, and the graininess of the image will deteriorate, and the photostimulable phosphor layer is undesirable because it tends to become transparent and the lateral spread of the #ill exhaustion excitation light in the 1i11 exhaustion band layer increases significantly, which tends to deteriorate the sharpness of the image.

Further, in manufacturing the radiation image conversion panel of the present invention, the deposition rate of the photostimulable phosphor layer is 0.05 μm/min to 30 μm/min.
Preferably it is 0 μm/min. Deposition rate is 0.05
If it is less than μm/min, the productivity of the radiation image conversion panel of the present invention is low and undesirable. Also, the deposition rate is 300
If it exceeds μm/min, it is difficult to control the deposition rate, which is not preferable.

The light-reflecting layer according to the present invention is provided on the surface of the photostimulable phosphor layer opposite to the surface on which the photostimulable excitation light is incident.

The light-reflecting layer may be provided directly on the surface of the stimulable phosphor layer, or it may be provided through a subbing layer to enhance the adhesion between the light-reflecting layer and the stimulable phosphor layer. may be provided.

The light reflecting layer can be applied to the present invention as long as the door surface has a different optical T degree (different refractive index) and a smooth surface. Ceramic smooth surface.

For the nationwide surface, a light reflective layer may be formed on the surface of the support or photostimulable phosphor layer by vapor deposition, sputtering, ion plating, or plating, or by laminating metal foil. Good too.

A vapor phase deposition method such as the vapor deposition method described above for gold 5 is particularly preferred because it facilitates the formation of a light-reflecting layer, and the layer can be formed regardless of the shape of the layer surface such as the support.

Metals used include aluminum, silver, chromium, nickel, platinum, rhodium, tin, and the like.

When a ceramic or metal sheet is used for the light-reflecting layer described above, the light-reflecting layer may also serve as a support, and a stimulable phosphor may be deposited in a vapor phase on the light-reflecting surface side. Bye.

The thickness of the light reflecting layer according to the present invention is generally 0.01 to 50 μm.
m is preferable, and it is preferable to have an average reflectance of 50% or more, more preferably 70% or more, for stimulated excitation light and/or light in the stimulated emission wavelength region.

The reflectance is determined using an integrating sphere spectrophotometer.

In the radiation image conversion panel of the present invention, for the purpose of further improving the sharpness of the obtained image, the original incident side may be colored with more photostimulation than the light reflection layer of the radiation image conversion panel. .

In the present invention, the coloration that is stronger on the side where the photostimulable excitation light is incident than the light reflection layer of the negative panel of the radiation image liquid 1 is applied to the entire layer of the photostimulable phosphor layer or to the layer. The surface layer, the layer near the light-reflecting layer, the undercoat layer, the protective layer, or two or more of these, or on the surface of the layer or between the layer and the light-reflecting layer. A colored layer is provided, and it is particularly preferable to provide a colored layer between the light reflecting layer and the stimulable phosphor layer. The coloring agent used for the coloring is a coloring agent that absorbs at least a part of the ``6fj excitation source'' for causing the stimulable phosphor to stimulably emit light. a,
In particular, depending on the type of the applied photostimulable phosphor, the average reflectance of the radiation image conversion panel to the source of the stimulated excitation light wavelength region is set to be smaller than the average reflectance of the radiation image conversion panel to light in the stimulated emission wavelength region. It is preferable to have light absorption characteristics.

In terms of U-removal properties of images, the colorant has a high absorption rate for light in the wavelength range of photostimulable excitation light of the photostimulable phosphor (the average reflectance of the radiation image conversion panel for light in this wavelength range is small). ) is better, and from the viewpoint of sensitivity, it is better that the absorption rate of the photostimulable phosphor for light in the stimulated emission wavelength region is small (the average reflectance of the radiation image conversion panel for light in the wavelength range is large). More specifically, the average reflectance of a radiation image conversion panel colored with a colorant to light in the stimulated emission wavelength range is the average reflectance of an equivalent uncolored radiation image conversion panel to light in the same wavelength range. The average reflectance of a radiation image conversion panel colored with a colorant to light in the stimulated excitation light wavelength region is preferably 20% or more of the same wavelength of an equivalent radiation image conversion panel that is not colored. It is preferable that the average reflectance for light in the area is 95% or less.

The coloring agent may be either an organic or inorganic coloring agent, but in terms of hue, blue to green coloring agents are useful.

As an organic colorant, Zapon Fast Blue 3G (
Hoechst), Nistrol Prill Blue N-3RL (
Sumitomo Chemical 1! ! U, D&C Blue j≦1 (manufactured by National Aniline), Spirit Blue (manufactured by Hodogaya Chemical), Oil Blue A603 (manufactured by Orient), Kitten Blue A (
(manufactured by Ciba Geigy), Eisenriki Chiron Blue GLH (manufactured by Hodogaya Chemical), Lake Blue AF)! (manufactured by Kyowa Sangyo),
Primodianin 5GX (manufactured by Inabata Sangyo), Prill Acid Green 6BH (manufactured by Hodogaya Chemical), Cyanine Blue BN
Rs (manufactured by iyo ink), Lionol Blue SL (manufactured by toyo ink), etc. are used.

Also, color index //'24411.2316
Q, '741BQ, '74200.22800°231
50.23155, 24401, 14880.1505
0,15706.15'707,17941.7422
0,13425,13361゜13420.11836
, 74140, 7438Q, and 74350.74460.

Examples of inorganic colorants include ultramarine blue, cobalt blue, cerulean blue, monochrome chromium, TiO□-Zylo-
C! Examples include oO-NiO pigments.

In the radiation image conversion panel of the present invention, the photostimulable phosphor refers to a photostimulable phosphor that is stimulated by optical, thermal, mechanical, chemical, or electrical stimulation (stimulable phosphor) after being irradiated with the first light or high-energy radiation. A phosphor that exhibits stimulated luminescence corresponding to the initial light or the amount of high-energy radiation irradiated by the phosphor. It is a phosphor that shows . Examples of the stimulable phosphor used in the radiation image conversion panel of the present invention include Ba5(+, : Ax (lFj, A is Dy, T
at least one of b and Tm, and X is O, QO
1≦x1mol%. ), Mg5O< : kx (
However, A is either Ho or Dy, and 0.0
01≦X≦1 mol %), SrSO4 described in JP-A-48-80489:
Ax (where A is at least one of Dy, Tb and Tm, and X is 0001≦x (1 mol%). , Na25o4.CaSO4 and BaS
At least one of Mn, Dy and Tk) in O4 etc.
Phosphors doped with seeds, EeO, LiF, MgSO4 and CaF described in JP-A-52-3Q4B7
2nd class phosphor, described in JP-A No. 53-39277, Li2B, ○=:(!u, Ag, etc. phosphor, described in JP-A-54-47883) Li2O・(
B202)x: Ou (where X is 2 (x≦3), and Li2O-(B202)x: Cu, Ag (where X is 2
<x≦3) etc., U.S. Patent No. 3.859. ．． 527
SrS described in the issue: Ce, Sm,
SrS: Eu, Sm-, La20. S:
mu, Sm and (Zn, Cd) S: M
Examples include phosphors represented by n, X (where X is halogen).

In addition, Zn described in Japanese Patent Application Laid-open No. 55-12142
S: Ou, Pb phosphor, general formula is BaO・xA
12o3: Barium aluminate phosphor represented by Eu (however, 08≦X≦10), and the general formula is M 0-x
SiO2:A (where M is Mg, Oa, Sr, Zn
, Cd or Ba, and A is Ce, Tb, Eu,
At least one of Tm, Pb, Tl, Bi, and Mn, and X satisfies 0.5≦x (2,5).

) is an alkaline earth gold silicate-based phosphor. In addition, the general formula % formula % (where X is at least one of Br and C1,
x, y and θ are each O (x+y≦0.6, xy≠0
and 10-6≦e≦5×10-2. ), the general formula of which is described in JP-A-55-12144 is LnOX:,zA (where Ln represents at least one of La, Y, Gd and Lu). , X represents C1 and/or Br, A+jOe and/or Tb, and X represents a number satisfying O(x (0, 1).

) The general formula of the phosphor described in JP-A-55-12145 is (Eal-jcMn, ) FX : yA (f tan M
IT is at least one of Mg, Ca, Sr, Zn and Cd; X is at least one of CI, Er and ■; A is Eu, Tb, Ce, Tm
.

Dy, Pr, Ha, Nd, Yb and TDr
2 and y represent numbers that satisfy the conditions O≦X≦06 and O≦y≦0.2. BaFX:
and X is at least one of C1, Br and I,
A is for work.

At least one of TI, Gd, Sm and Zr
, and X and y are O(x≦2×10 and 0
<y≦5×10. ] The phosphor represented by 1978-1600'78 has the following formula: M"FX-xk: yLn (However, Mg, C!a, Ba, Sr, Z
At least one of n and cd, A is BeO, Mg
O.Cao.

SrO, BaO, ZnO, k1203. Y2O3+
La2O3+ Engn203 +5i02. Tie,
, ZrO2, GeO2, SnO2, Nb2O,,T
a2O.

and The, at least one of the following:
.

, Tb, Ce, Tm, Dy, Pr, Ho,
Nd, Yb, Er.

is at least one of Sm and Gd, and X is CI
, Br and I, and X and y
are numbers satisfying the conditions of 5×10≦X≦05 and O<y≦02, respectively. ) Represented by rare earth element activation 2
Valent metal fluoride/L olohalide phosphor, general formula is ZnS:
AXCdS: A, (Zn, (!d)S:A
, ZnS: A, X and aas: A, X (where A is Ou,
It is Ag, Au, or Mn, and X &j is 0. ], Japanese Patent Application Laid-Open No. 57-148285
Any of the following general formula % formula % described in the No.
.

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

At least one of CI, By- and ■, A is mu
.

Tb, Oe, Tm, Dy, Pr, Ha, N
d, Yb, Kr.

Represents at least one of Sb, Tl, Mn and Sn. In addition, X and y are numbers that satisfy the condition of o(r≦6.0≦y≦1.The phosphor represented by U is expressed by one of the following general formulas% formula% (where Re is La, Gd , Y, and Lu, A is an alkaline earth metal, Ba, Sr, Ca
At least one of them, X and xl represent at least one of F, Ol, and Br. Also, X and y are l
X 1 0-'< x (3X IO-',
I
/m 〈7×10−′ is satisfied. ), and a phosphor represented by the following general formula %: (where MT is at least one alkali gold selected from Li, Na, K, Rb and 0 days,
Mn is Ee, Mg, Oa, Sr, Ba, Zn
, Od, C! At least one selected from u and N1
It is a type of divalent metal. MnI is Sc, Y, La, Oe,
Pr, Nd, Pm.

Sm, Eu, G(1, Tb, Dy, Ho,
Er, Tm, Yb.

At least one type of metal selected from Lu, Al, Ga, and metal is one piece of royal gold. x, x' and X'' are F, cl.

At least one halogen selected from Er and (2). A is Eu, Tb, Ce, Tm, D
y, Pr.

Ho, Nd, Yb, Kr, Gd, Lu, Sm, Y, Tl
.

It is at least one metal selected from Na + A g , Cu, and Mg.

In addition, a is O≦a ('I9. (in the range of 0, 5), and C is 0<C≦0,2 Examples thereof include alkali halide phosphors represented by the following formula. In particular, alkali halide phosphors are preferred because they facilitate the formation of a fluorophore main layer by methods such as vapor deposition and sputtering.

However, the stimulable phosphors used in radiation image conversion panels are not limited to the above-mentioned phosphors. Any phosphor may be used as long as it exhibits the following.

The radiation image conversion panel of the present invention includes one or more of the above-mentioned photostimulable phosphors containing at least one type r1.
There may also be a group of 1) exhaustible phosphor layers consisting of a single exhaustive phosphor layer. Furthermore, the stimulable phosphors contained in each stimulable phosphor layer may be the same or different.

In the radiation image conversion panel of the present invention, when the light reflection layer or the photostimulable phosphor layer does not have self-supporting ability, a support for supporting the light reflection layer and the VJfl stimulable phosphor source is provided. A body is provided. Various polymer materials, glass, metals, etc. are used as the support, and include plastic films such as cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, triacetate film, and polycarbonate film, aluminum sheet, A metal sheet such as an iron sheet or a copper sheet, or a metal sheet having a coating layer of the gold persulfide is preferred.

The surface of these supports may be smooth or matte for the purpose of improving adhesion to the stimulable phosphor layer. Further, the surface of the support body may have an uneven portion 21 as shown in FIG. 2(a), or may have a structure in which spaced tile-like plates 23 are laid out as shown in FIG. 2(b). In the case of FIG. 2(a), the '1AII exhaustible phosphor layer is
), the sharpness of the image is further improved because it is subdivided by the uneven surface 21. Figure 2<b)
In the case of
As a result, the stimulable phosphor layer forms cracks 2 as shown in the cross-sectional view of FIG. 2(d).
Columnar blocks 25 of photostimulable phosphor separated by 6
As a result, the sharpness of the image is further improved.

Furthermore, these supports may be provided with a subbing layer in addition to the photostimulable phosphor layer or light reflective layer for the purpose of improving adhesion to the photostimulable phosphor layer or light reflective layer. . Also,
The film thickness of these supports varies depending on the material of the support used, but is generally 8'0 μm to 2000 μm.
From the viewpoint of handling, it is more preferably 80 μm to 1000 μm.
It is μm.

In the radiographic moxibustion panel of the present invention, the photostimulable phosphor layer is generally physically attached to the opposite side of the photostimulable phosphor layer from where the light reflecting layer is provided. Alternatively, a protective layer for chemical protection may be provided. This 1♀Mamoru,
The bow may be formed by applying a coating solution for a protective layer directly onto the photostimulable layer, or by applying a separately formed protective layer in advance on the photostimulable layer. It may be bonded.Materials for the protective layer include cellulose acetate, nitrocellulose, polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyester, polyethylene terephthalate, polyethylene, vinylidene chloride, nylon, etc. In addition, this protective layer is formed by a vapor deposition method, a sputtering method, etc.

SIN, AM0. The fR layer may be formed of an inorganic material such as. The thickness of these protective layers is generally 01 μm to 1 μm.
The thickness is preferably about 00 μm.

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

That is, in FIG. 3, 31 is a radiation generating device;
2 is a subject, 33 is a radiation #image conversion panel of the present invention, 4
4 is a stimulated excitation light source, 34 is a photoelectric conversion device that detects stimulated luminescence emitted from the radiation transmission image conversion panel, and 36 is a 3
5 is a device that reproduces No. 1 detected as an image, 37 is a device that displays the reproduced image, and 38 is a filter that separates stimulated excitation light and stimulated luminescence and allows only stimulated luminescence to pass through. . It should be noted that the elements after 35 are not limited to the above, as long as they can reproduce the optical information from 33 as an image in some form.

As shown in FIG. 3, radiation from a radiation generating device 31 passes through a subject 32 and enters a radiation image changing panel 33 of the present invention. The radiation q= of this incident radiation is absorbed by the stimulable phosphor layer of the line image conversion panel 33, the energy thereof is accumulated, and an accumulated radiation image is formed. Next, this accumulated image is excited with stimulated excitation light from the excitation light source 34 to emit stimulated luminescence. The radiation rmJ image converting panel 33 of the present invention does not contain a binder in the photostimulable phosphor layer and has a high directivity of the stimulable phosphor layer, so that scanning by the above-mentioned photostimulable excitation light is difficult. At the same time, the diffusion of the excitation light in the phosphorescent layer is suppressed.

Since the strength of the emitted stimulated luminescence is proportional to the accumulated radiation energy 1, this optical signal is photoelectrically converted by a photoelectric conversion device 35 such as a photomultiplier tube, and an image reproduction device 36
By reproducing the image as an image and displaying it on the image display device 37, a radiographic image of the subject can be observed.

(Example〕 Next, the present invention will be explained using an actual IM example.

Example 1 Chemically strengthened glass (thickness 400μm) with 1μ reflective layer
Silver vapor deposition was performed to a thickness of m.

Next, the support with the light reflecting layer formed thereon was placed in a vapor deposition device. Flucarino Ride stimulable phosphor (RbBr: 0.0006 Tl) was then placed in a water-cooled crucible and pressed into the shape of a crucible.

The evaporator was subsequently evacuated to a vacuum of 5×IO-'Torr. Next, while heating and maintaining the support at 150° C., power was supplied to the EiB gun to form the 'AS+I exhaustible phosphor. In order to obtain the desired stimulable phosphor layer, the deposition rate was detected by a film thickness monitor, and the deposition rate was 5 μm.
/minute.

The electron beam scans the surface of the stimulable phosphor in the crucible in a raster pattern.

Vapor deposition was terminated when the thickness of the stimulable phosphor layer reached 200 μm to obtain a radiation image conversion panel of the present invention comprising a support, a light reflecting layer, and a stimulable phosphor layer. .

Furthermore, the layer thickness of the photostimulable phosphor layer is 100 to 40011 m.
A heel radiation image conversion panel A consisting of a support, a light reflecting layer, and a stimulable phosphor layer was produced by changing the range within the range of Lf>.

The radiation image conversion panel A of the present invention was evaluated as +', T2 by the radiation sensitivity test and image sharpness test described below.
fjllj L/, the results are shown as curve A in Table 5.

(1) Radiation sensitivity test After irradiating the radiation image conversion panel with IQ mR of X-rays at a tube pressure of 80 KV'p, a He-Ne laser source (6
33 nm), and the stimulated luminescence emitted from the stimulable phosphor layer is photoelectrically converted by a photodetector' (photomultiplier tube).
The sensitivity to lines was investigated.

The sensitivity to X-rays is expressed in relative brightness, with the width of the dissipated line image conversion panel A of the present invention having an exhaustive phosphor layer thickness of 2 Q Q 71 m as 100.

(2) Image sharpness test The radiation of the present invention thus obtained: a Image conversion panel A was irradiated with 10 mR of xlJ with a tube voltage of 80 KVp, and then stimulated with He-Ne laser light (633 nm). and optically detect the stimulated luminescence emitted from the photostimulable phosphor layer.
? The amount of alcohol was converted into light using an RI (photomultiplier tube), the amount of alcohol was reproduced as an image using an image reproducing device, and the modulation transfer function (MTF) of the image was examined from the obtained image.

Note that the modulation transfer function (MTF) is a value when the spatial frequency is 2 cycles/agony.

(Example 2) Instead of using the support provided with the light-reflecting layer in Example 1, polished chemically strengthened glass (thickness: 400 μm) whose surface was sufficiently polished and whose reflective surface was used was used. Other than that, various radiation image conversion panels B of the present invention having a photostimulable fluorescent layer were produced in the same manner as in Example 1.

The radiation image conversion panel B of the present invention has a radiation sensitivity and an image release property evaluated by 51z in the same manner as in Actual...11,
The results are shown as curve B in Figure 4.

(Example 3) In Example 1, instead of using a support provided with a light-reflecting layer, an aluminum plate with anti-n=J side made of a clear material that had been cleaned of dirt was used. ; Ill diameter: 400 μm)
Various radiation image conversion panels C of the present invention each having a 11-band phosphor layer were fabricated.

The radiation image conversion panel C of the present invention is the same as Example 1 and 4.
．． n, radiation Q-f radiation sensitivity and image 1'J! The sharpness of J
'F value, and the result is shown as the 4th garden song IF4c.

Comparative Example 1 In Example 3, except that the stimulable phosphor layer was directly deposited on an aluminum plate (width 400 μm) having an oxide film with an average reflectance of 40% for SII exhaustion excitation source and 1111 exhaustion emission. In the same manner as in Example 3, radiation image conversion panels P of various ratios are constructed of an aluminum plate and a photostimulable phosphor layer. ! I built J.

Radiation Q of the ratio axis; f-ray image conversion panel P is in Examples 1 to 3.
The radiation sensitivity and image sharpness were evaluated in the same manner as above, and the results are shown as curve P in FIG.

Ratio Example 2 Alkali halide yiII exhaust 'lr2 light f$(
Methyl ethyl ketone was added to a mixture of RbBr: o, ooo6Tg) particles and linear polyester resin, and 0
Then, nitrocellulose with a degree of nitrification of 11.5% was added to prepare one dispersion containing phosphor particles in a dispersed state. Next, tricresyl phosphate, n-butanol, and methyl ethyl ketone were added to this dispersion, and the mixture was sufficiently stirred using a propeller mixer to uniformly disperse the phosphor particles, and the binder and fluorescein Mixing ratio with body is 1:2
A coating liquid having a weight of 1 U and a viscosity of 25 to 35 PS (256C) was used.

This coating solution was applied onto the support in the same manner as above, and then dried to a layer thickness of approximately 200 μm.
A stimulable phosphor layer of m was formed.

In this way, the layer thickness of the photostimulable phosphor layer is adjusted to 100 to 40 mm.
Various comparative radiation image conversion panels Q, each consisting of a support and a stimulable phosphor layer, were manufactured by varying the thickness within a range of 0 μm.

The radiation sensitivity and image sharpness of the comparative radiation image conversion panel Q were evaluated in the same manner as in Examples 1 to 3, and the results are shown as curve Q in FIG.

As is clear from FIG. 4, the radiation image conversion panels A, B, and C of the present invention have the same radiation sensitivity compared to the conventional radiation image conversion panels P and Q, and the sharpness of the image is improved. On the other hand, if the image sharpness is the same, the radiation sensitivity is high.

(Effects of the Invention) As described above, the stimulable phosphor layer is formed by bonding the stimulable phosphor layer, has striae in the layer thickness direction and has a frost columnar shape, and uses thin columnar crystals and the layer of the layer. By providing a light-reflecting layer at the interface, it was possible to improve both sensitivity and sharpness, which were contradictory.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of a single layer of unexploded 1j) J photostimulable fluorophore, in which 1ffi (a) shows cross-sectional electrons in a layer consisting of microcrystals formed by the Kirimeki H11 method. The micrograph (b) is a schematic cross-section showing the directionality of light in the layer. FIGS. 2(a) and (b) show 1ii of the support according to the present invention.
Exhaustive fluorescent
c) and (d) show cross sections when a stimulable phosphor layer is formed on the layer surface. FIG. 3 is a schematic diagram of the radiation image conversion method used in the present invention. FIG. 4 (1) is a diagram showing the relative sensitivity and image sharpness of the radiation image conversion panels A, E. C of the present invention and the comparative radiation image conversion panels P, Q. 21 and 22. ... Support body 23 ... Tile plates 24 and 25 ... Stimulable phosphor layer 27 ... Light reflection layer 26 ... Cracks 31 ... Radiation generating device 32 ... Subject 33.・Radiation image conversion panel 34 ・・Insen excitation light source 38 ・・Filter Applicant Roku Konishi Photo Industry Ajishiki Company 2 Figures (a) (b) Figure 3

Claims (6)

[Claims] (1) In a radiation image conversion panel having a photostimulable phosphor layer, the photostimulable phosphor layer is composed of a phosphor phase having a bonded form; 1. A radiation image conversion panel comprising a light reflecting layer on the interface side of one of the phosphor layers. (2) The phosphor phase formed by bonding the stimulable phosphor layers has striae in the layer thickness direction. Radiographic image conversion panel. (3) The light reflecting layer has an average reflectance of 50% or more for light in the wavelength range of stimulated excitation light and/or stimulated emission light, or 2. The radiation image conversion panel according to item 2. (4) The radiation image conversion panel is colored on the side where the photostimulable excitation light is incident rather than the light reflection layer, and the average value for light in the wavelength region of the photostimulable excitation light transmitted through the photostimulable phosphor layer. The radiation image conversion panel according to claim 1, 2, or 3, wherein the reflectance is smaller than the average reflectance for light in the synonymous stimulated emission wavelength region. (5) The radiation according to claims 1 to 4, characterized in that the radiation image panel is laminated in this order: the support, the light reflection layer, and the stimulable phosphor layer. Image conversion panel. (6) The radiation image conversion panel according to any one of claims 1 to 5, wherein the reflective surface of the light reflective layer is a metal surface.