JP2000155200A - Stimulable phosphor sheet and radiation image recording and reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high sharpness without lowering sensitivity by constituting the sheet of a barrier wall containing a stimulable phosphor finely dividing the sheet in the plane direction and a stimulable phosphor filling region showing reflection characteristic different from the barrier wall. SOLUTION: A stimulable phosphor sheet 10 used for a radiation image recording and reproducing method, for instance, comprises a barrier wall 11 containing a stimulable phosphor and a stimulable phosphor filling region 12 surrounded by the barrier wall 11. The barrier wall 11 and the stimulable phosphor filling region 12 are different in the reflectivity characteristic of excitation light by various prescribed methods of adjustment of a phosphor/binder ratio, addition or the like of a white pigment. In the case where a radiation image having high sharpness is sought it is advantageous that the reflectivity of the barrier wall 11 is heightened. Due to convenience or the like of transportation and handleability, the stimulable phosphor sheet 10 is preferably provided with a supporter on one side and a transparent protection film on the other side. The reflection layer of excitation light and accelerated phosphor emission light or the absorption layer of the excitation light is provided between the supporter and the sheet 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stimulable phosphor sheet used for a radiation image recording / reproducing method utilizing the stimulability of a stimulable phosphor, and a radiation image using the stimulable phosphor sheet. The present invention relates to a recording / reproducing method and a radiation image information reading method.

[0002]

2. Description of the Related Art As an alternative to a radiographic method using a combination of a radiographic film and an intensifying screen, a radiographic image recording / reproducing method using a stimulable phosphor (also referred to as a radiographic image conversion method) is known. ing. This method uses a radiation image conversion panel provided with a stimulable phosphor layer (stimulable phosphor sheet) on a support, and transmits radiation transmitted through a subject or emitted from a subject. Exciting the stimulable phosphor by irradiating the stimulable phosphor sheet with the stimulable phosphor and then irradiating the stimulable phosphor with electromagnetic waves (excitation light) such as visible light or infrared light. By
Radiation energy stored in the stimulable phosphor is emitted as fluorescence (stimulated luminescence), and the fluorescence is read photoelectrically to be converted into an electric signal. From this electric signal, a radiation image of a subject or a subject is obtained. Is reproduced as a visible image. The read-out radiation image conversion panel erases radiation energy remaining in the phosphor layer, and is repeatedly used in a similar radiation image recording / reproducing method.

A radiation image conversion panel used in the above-described radiation image recording / reproducing method generally has a basic structure in which a support sheet, a stimulable phosphor layer (stimulable phosphor sheet), and a protective film are laminated in this order. Having a configuration. The stimulable phosphor layer usually comprises stimulable phosphor particles and a binder for supporting the stimulable phosphor particles in a dispersed state. However, some of the stimulable phosphor layers are formed of aggregates of stimulable phosphors that do not contain a binder and are formed by a vapor deposition method, a sintering method, or the like. Further, a stimulable phosphor layer in which a polymer substance is permeated into the gaps between the aggregates of the stimulable phosphor is also known.
Any of the radiation image conversion panels having the stimulable phosphor layer can be used in the above-described radiation image recording / reproducing method.

[0004] In the radiation image recording / reproducing method, radiation image information is generally read by irradiating the upper surface of a stimulable phosphor sheet with excitation light, and stimulating light emitted from the phosphor is provided on the excitation light irradiation side. This is performed by taking out light with a condensing light guide and performing photoelectric conversion to obtain an image signal (single-side condensing method). However, when it is desired to extract as much stimulating light emitted from the phosphor as possible, or for a latent image composed of radiation energy formed in the stimulable phosphor sheet, the energy intensity changes in the depth direction of the sheet. When it is desired to obtain the change in the energy intensity (intensity distribution) as radiation image information during the operation, the method of concentrating photostimulated light from both upper and lower sides of the photostimulable phosphor sheet (double-sided condensing method) It's being used. The radiation image recording / reproducing method using the double-sided condensing method is described in, for example, JP-A-55-87970.

It is desirable that the radiation image conversion panel used in the above-described radiation image recording / reproducing method has high sensitivity and can reproduce a high-quality radiation image. That is, as a typical application of the radiation image recording / reproducing method, there is formation of a radiation image for medical diagnosis using X-rays. This is because it is desired to be able to obtain a radiographic image having a degree).

The sharpness of a radiation image formed in the radiation image recording / reproducing method mainly depends on diffusion of excitation light in the stimulable phosphor layer of the radiation image conversion panel. In other words, the radiation energy latent image recorded on the stimulable phosphor layer is generated by irradiating the surface of the phosphor layer with the excitation light in a time series while moving the beam-like excitation light. The stimulated emission light is read out by sequentially condensing, but when the irradiated excitation light diffuses inside the phosphor layer (especially in the plane direction), the excitation light goes beyond the irradiation area and is similarly irradiated around the irradiation area. As a result, phosphor particles having radiation energy are also excited, and the radiation energy of the phosphor outside the irradiation area is also extracted as photostimulated light together with the radiation energy of the phosphor in the irradiation area. This is because

[0007] It is already known to provide an excitation light-reflective partition for subdividing the phosphor layer in a plane direction in the phosphor layer in order to avoid diffusion of the excitation light in the stimulable phosphor layer. I have. JP-A-59-202100 discloses that
Radiation image conversion panel provided with a stimulable phosphor layer on the substrate,
It describes that a honeycomb structure composed of a plurality of small cells divided by a partition member is provided, and each of the small cells is filled with a stimulable phosphor. JP-A-62-36599 discloses that a large number of recesses having a ratio of the diameter of an opening to the depth of 1: 3.5 or more are regularly provided on one surface of a support,
In addition, a radiation image conversion panel having a structure in which the concave portion is filled with a stimulable phosphor is described. Tokuhyo Hei 5-512
No. 636 describes a method for manufacturing a pixel phosphor using a mold.

Japanese Patent Laid-Open Publication No. 2-129600 describes a radiation image conversion panel in which a stimulable phosphor is filled in a hole of a support plate having a large number of holes in a thickness direction. JP-A-2-280100 describes a stimulable phosphor sheet in which a phosphor is filled on a substrate on which a honeycomb-shaped microstructure is formed.

[0009]

SUMMARY OF THE INVENTION A stimulable phosphor formed by forming a large number of recesses on the surface of a conventionally known substrate or support and filling the recesses with stimulable phosphor particles. A radiation image conversion panel having a layer is useful for forming a radiation image having excellent image quality, particularly sharpness, since the diffusion of excitation light is prevented by a support material portion serving as a partition in the phosphor layer. However, since a part of the phosphor layer is occupied by the support material wall, a problem arises that the filling amount of the phosphor particles per unit volume of the phosphor layer necessarily decreases. The reduction in the amount of the phosphor per unit volume in the phosphor layer results in a decrease in the amount of X-rays absorbed by the phosphor layer, and as a result, a decrease in the sensitivity of the stimulable phosphor sheet. The sensitivity of the stimulable phosphor layer can be increased by increasing the thickness of the phosphor layer, but increasing the thickness of the phosphor layer will, in turn, decrease the sharpness of the resulting image. Results.

An improvement in the sensitivity of the stimulable phosphor sheet or the radiation image conversion panel is effective, for example, in reducing the amount of X-ray irradiation on the human body during X-ray imaging in medical diagnosis. There is a great demand for the development of a stimulable phosphor sheet or a radiation image conversion panel that provides a radiation image with high sharpness.

[0011]

SUMMARY OF THE INVENTION According to the present invention, after a radiation image is recorded as a latent image, stimulating light is emitted from the latent image by irradiating with excitation light, and then the stimulating light is emitted. A stimulable phosphor sheet used in a radiation image recording / reproducing method comprising reproducing a radiation image by electrically processing, wherein the stimulable phosphor sheet subdivides the sheet along a plane direction. A stimulable phosphor-containing partition for partitioning,
A stimulable phosphor-filled region, which is defined by the stimulable phosphor-containing partition and has a different reflection characteristic to the excitation light from the stimulable phosphor-containing partition. In the phosphor sheet.

The stimulable phosphor-filled region in the stimulable phosphor sheet of the present invention is prepared so as to exhibit a higher or lower reflectance for excitation light than the stimulable phosphor-containing partition. .

According to the present invention, the stimulable phosphor sheet of the present invention is irradiated with radiation transmitted through a subject or emitted from a subject, and the stimulable phosphor sheet is exposed to the subject or the subject. After recording the radiation image of the specimen as a latent image, one side of the stimulable phosphor sheet is irradiated with excitation light, and the stimulable light emitted from the latent image is emitted from both sides of the stimulable phosphor sheet. There is also a double-sided condensing type radiation image recording / reproducing method comprising photoelectrically reading the image signal, converting the image signal into an image signal, and reproducing the radiation image from the image signal.

According to the present invention, there is also provided a stimulable phosphor sheet in which radiation image information is stored and recorded as a latent image on the stimulable phosphor sheet of the present invention as described above, while transferring the stimulable phosphor sheet in the plane direction, or by exciting light. While moving the irradiation device in the plane direction of the stimulable phosphor sheet, the stimulable phosphor sheet is irradiated with excitation light linearly in a direction orthogonal to the transfer direction, and the stimulable phosphor sheet is irradiated. There is also a radiation image information reading method which sequentially and one-dimensionally photoelectrically detects stimulated emission light emitted from the latent image of the excitation light irradiated portion to obtain the radiation image information as an electric image signal.

In the stimulable phosphor sheet of the present invention, each of the stimulable phosphor-filled region and the stimulable phosphor-containing partition contains at least stimulable phosphor particles and a binder. Is desirable. Further, it is desirable that the stimulable phosphor-filled region is divided while being surrounded by a stimulable phosphor-containing partition.

The stimulable phosphor sheet of the present invention is desirably provided with an excitation light reflecting layer or a stimulable luminescent light reflecting layer on the surface opposite to the side irradiated with the excitation light. In addition, the stimulable phosphor-containing partition may have its top exposed on the surface of the phosphor layer of the stimulable phosphor sheet,
Alternatively, the entire stimulable phosphor-containing partition may be embedded in the phosphor layer, but the height thereof is in the range of 1/3 to 1/1 of the thickness of the stimulable phosphor sheet. Is desirable.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The stimulable phosphor sheet of the present invention comprises:
A stimulable phosphor sheet used in the radiation image recording / reproducing method, wherein the stimulable phosphor sheet comprises a stimulable phosphor-containing partition which subdivides the sheet along a planar direction; For the excitation light partitioned by the stimulable phosphor-containing partition wall, the stimulable phosphor-containing partition wall and a stimulable phosphor-filled region having a different reflection characteristic from the stimulable phosphor-containing partition wall have a feature of being a basic configuration. By the presence of the stimulable phosphor-containing partition walls, without reducing the sensitivity caused by the presence of the normal partition walls, by suppressing the diffusion of excitation light in the planar direction in the stimulable phosphor sheet. Enables formation of a radiation image having high sharpness.

Although the stimulable phosphor sheet of the present invention does not need to be provided with a support or a protective film in terms of its basic performance, it does not require the convenience of transporting and handling the stimulable phosphor sheet. In order to avoid characteristic changes, support on one side,
It is desirable to provide a transparent protective film on the other side. For this reason, in the following description, a relatively thick sheet-like support is provided on one side surface, and a relatively thin and transparent film-like protective film is provided on the other side surface. The stimulable phosphor sheet of the present invention will be described by taking a typical structure (which may be referred to as a radiation image conversion panel) as an example. In the case of taking the structure of the radiation image conversion panel, the stimulable phosphor sheet may be referred to as a stimulable phosphor layer or simply a phosphor layer.

The support of the radiation image storage panel is usually a sheet or film-like support having a thickness of 50 μm to 1 mm made of a flexible resin material. The support may be transparent, or the support may be filled with a reflective material (eg, titanium dioxide particles, barium sulfate particles) for reflecting excitation light or stimulated emission light, Alternatively, a gap may be provided. Alternatively, the support may be filled with a light-absorbing material (eg, carbon black) for absorbing excitation light or stimulated emission light. Examples of such a resin material include various resin materials such as polyethylene terephthalate, polyethylene naphthalate, aramid resin, and polyimide resin. If necessary, the support may be a sheet material other than a resin material sheet such as a metal sheet, a ceramic sheet, and a glass sheet. An auxiliary functional layer such as a light reflecting layer, a light absorbing layer, an adhesive layer, and a conductive layer may be provided on the surface of the support on which the phosphor layer is provided. May be formed. On the other hand, a friction-reducing layer or a scratch-resistant layer may be provided on the surface of the support on which the phosphor layer is not provided in order to improve the transportability or the scratch resistance.

A stimulable phosphor layer (stimulable phosphor sheet) is provided on the surface of the support as described above. The stimulable phosphor layer comprises a stimulable phosphor-containing partition which is subdivided along its plane direction, and a stimulable phosphor for the excitation light partitioned by the stimulable phosphor-containing partition. And a stimulable phosphor-filled region exhibiting different reflection characteristics. Such a stimulable phosphor layer (stimulable phosphor sheet)
Will be described with reference to the accompanying drawings.

FIG. 1 shows a stimulable phosphor sheet 10 of the present invention.
(1), an enlarged perspective view (2), a part of which is enlarged to clarify the surface configuration, and a cross-sectional view (3) taken along line II in the enlarged perspective view (2). Show.
The shaded portions in (2) and (3) of FIG. 1 are the stimulable phosphor-containing partition walls 11, and the portions surrounded by the hatched portions are the stimulable phosphor-filled regions 12. The thickness of the stimulable phosphor sheet (stimulable phosphor layer) is usually in the range of 20 μm to 1 mm. Preferred layer thicknesses are in the range from 50 μm to 500 μm. The width of the stimulable phosphor-containing partition wall is desirably in the range of 5 μm to 50 μm, and the width of the stimulable phosphor-filled region (average width in the planar direction) is in the range of 20 μm to 200 μm. It is desirable.

In the stimulable phosphor sheet shown in FIG. 1, both the top and bottom of the stimulable phosphor-containing partition are exposed on both surfaces of the phosphor layer. One of them may be buried in the phosphor layer. However, the height of the partition is 1/3 to 1 of the thickness of the stimulable phosphor layer.
/ 1 is desirable. FIG. 2A is a cross-sectional view showing a state in which the top of the stimulable phosphor-containing partition is not exposed to the upper surface of the phosphor layer but is embedded in the phosphor layer. FIG. 2B is a cross-sectional view showing a state in which the support 13 is provided on the lower surface of the stimulable phosphor sheet of FIG. 2A and the protective film 14 is provided on the upper surface. is there.

In the stimulable phosphor sheet of the present invention shown in FIG.
The figure shows that the stimulable phosphor-containing partition walls 11 are formed in a lattice shape, and a substantially square area defined by the lattice is filled with the stimulable phosphor. The shape and position of the partition walls can be changed as appropriate. FIG. 3 shows an example of a variation in the shape of such a stimulable phosphor-containing partition wall. In the configuration of FIG. 3A, a strip-shaped stimulable phosphor-containing partition 11 is provided, and the partition 12 is partitioned into a strip to fill a region 12 with the stimulable phosphor. When a radiation image is read from the stimulable phosphor sheet having the configuration shown in FIG.
The irradiation of the excitation light is advantageously performed while scanning in a direction crossing the strip-shaped partition 11 and the region 12.

In the configuration shown in FIG. 3B, a stimulable phosphor-containing partition 11 having a wavy shape is provided, and the stimulable phosphor is filled in a region 12 which is divided into a band by the partition 11. ing. When a radiation image is read from the stimulable phosphor sheet having the configuration of FIG. 3B using excitation light, the irradiation of the excitation light is performed in such a direction as to cross the strip-shaped partition 11 and the region 12. It is advantageous to do it while scanning.

In the configuration of FIG. 3C, the stimulable phosphor-containing partition wall 11 is formed so as to surround the column-shaped stimulable phosphor-filled region 12.

The stimulable phosphor used in the stimulable phosphor-filled region of the stimulable phosphor sheet and the stimulable phosphor-containing partition walls may be irradiated with excitation light having a wavelength in the range of 400 to 900 nm. Stimulable phosphors that exhibit stimulated emission in the wavelength range of 300 to 500 nm are preferred. Examples of such a stimulable phosphor are described in detail in JP-A-2-193100 and JP-A-4-310900. Particularly preferred stimulable phosphors are alkaline earth metal halide phosphors activated by europium or cerium (eg, BaFBr: Eu or BaFBr).
I: Eu) and a cerium-activated rare earth oxyhalide phosphor. The stimulable phosphor used for the stimulable phosphor-filled region and the stimulable phosphor-containing partition may be the same or different from each other, but usually, the same stimulable phosphor is used. Used. Alternatively, a stimulable phosphor having a composition different from that of the stimulable phosphor on one side and having an excitation wavelength and a stimulable emission wavelength in the same wavelength region may be used.

The stimulable phosphor is formed into particles, and is dispersed and dissolved in a suitable organic solvent together with a binder to form a coating solution. The ratio of binder to phosphor in this coating solution is usually 1: 1.
-1 to 100 (weight ratio). This ratio is particularly preferably in the range of 1: 8 to 1:40 (weight ratio). Various types of resin materials are also known for the binder that disperses and supports the stimulable phosphor particles in the stimulable phosphor-filled region and the stimulable phosphor-containing partition walls. Also in the formation of the stimulable phosphor layer of the body sheet, it can be appropriately selected and used from any resin material mainly including those known binder resins.

The stimulable phosphor sheet of the present invention has a stimulable phosphor-containing partition for subdividing the sheet along a plane, and the stimulable phosphor-containing partition is partitioned by excitation light. And the stimulable phosphor-containing partition wall and a stimulable phosphor-filled region having different reflection characteristics. There are an embodiment in which the filled region is lower than the partition wall containing the stimulable phosphor, and 2) an embodiment in which the reflectance to the excitation light is higher in the filled region than the partition wall containing the stimulable phosphor. Among them, the stimulable phosphor sheet having the constitution 1) is advantageous particularly when a radiation image having high sharpness is required.

In order to make the stimulable phosphor-filled region or the stimulable phosphor-containing partition wall exhibit a high reflectance to the excitation light, for example, the weight ratio of the phosphor / binder is relatively set. Increase the size of phosphor particles (average particle diameter)
Relatively small (fine particles), white pigment (eg,
Methods such as addition of particles that reflect excitation light, such as titanium dioxide, barium sulfate) or phosphor particles that do not exhibit stimulated emission, can be used, and these methods can be used alone or in combination. Alternatively, an excitation light reflecting thin film can be provided between the stimulable phosphor-filled region and the stimulable phosphor-containing partition.

On the other hand, in order to make the stimulable phosphor-filled region or the stimulable phosphor-containing partition wall exhibit a low reflectance with respect to the excitation light, for example, the ratio of the phosphor / binder is relatively low. Methods such as reducing the size of the phosphor particles relatively, increasing the size (average particle size) of the phosphor particles, and adding a dye that absorbs excitation light can be used.
They can be used alone or in combination. Alternatively, an excitation light absorbing thin film can be provided between the stimulable phosphor-filled region and the stimulable phosphor-containing partition.

The stimulable phosphor sheet of the present invention is, for example,
A stimulable phosphor sheet formed in a honeycomb shape by forming a large number of recesses (holes) or through holes is formed in advance, and a binder solution containing the stimulable phosphor particles in a dispersed state in the recesses or through holes is prepared. It can be manufactured by coating and then drying the coated layer. Alternatively, a method may be used in which the raw material of the stimulable phosphor is filled in the concave portions or the through holes of the honeycomb-shaped stimulable phosphor sheet and fired. Further, a method of depositing the stimulable phosphor on the surface of the honeycomb-shaped stimulable phosphor sheet provided with the concave portions or the through holes can also be used. Alternatively, the stimulable phosphor dispersed in a honeycomb-shaped stimulable phosphor or a thermosetting polymer, and the honeycomb-shaped stimulable phosphor is pressed into a plastic stimulable phosphor sheet to form a honeycomb-shaped stimulable phosphor. A luminescent phosphor sheet can also be manufactured. When pushing the honeycomb body, a heating and / or pressing operation may be performed.

The honeycomb-shaped stimulable phosphor sheet can be produced, for example, by a method in which the stimulable phosphor sheet is subjected to an etching treatment using lithography such as dry etching. For the specific dry etching method that can be used, refer to
The method described in JP-A-2-36599 can be referred to. Alternatively, a method of performing an etching process using a laser processing method using an LIGA process, an excimer laser, or the like can also be used.

The stimulable phosphor sheet of the present invention comprises a stimulable phosphor film forming a stimulable phosphor-filled region and a stimulable phosphor film forming a stimulable phosphor-containing partition. Can be manufactured by using the laminated slice method shown in FIGS. 4 to 10 of the accompanying drawings described below.

First, a stimulable phosphor film (hereinafter referred to as phosphor film A) comprising a stimulable phosphor particle and a binder forming a stimulable phosphor-filled region as shown in FIG. ) And a plurality of stimulable phosphor films (hereinafter referred to as phosphor films B) each comprising stimulable phosphor particles forming a stimulable phosphor-containing partition wall and a binder. Next, as shown in FIG. 5, after a large number of phosphor films A and phosphor films B are alternately laminated to obtain a laminate, pressure is applied as shown in FIG. While heating the laminate, the adjacent phosphor films are brought into close contact with each other to obtain a laminate block.

Next, as shown in FIG. 7, the laminate block is sliced along the lamination surface, and the strips of the phosphor film A and the phosphor film as shown in FIG. A large number of striped phosphor films having a configuration in which strips of B are alternately arranged are prepared.

Next, the striped phosphor film of FIG. 8 and the above-mentioned phosphor film B (stimulable phosphor film forming the stimulable phosphor-containing partition wall) are shown in FIG. Then, a large number of sheets are alternately laminated, and then, pressure and heat are applied by a method similar to the method shown in FIG. 6 to produce a laminated block. Finally, as shown in FIG. 10, the laminate block is sliced along the laminate surface where the end face of the phosphor film A and the end face of the phosphor film B appear, thereby stimulating the present invention. Phosphor sheet can be obtained.

On one surface of the stimulable phosphor sheet of the present invention, a reflection layer made of a material reflecting excitation light and / or stimulable light can be provided. However, when the stimulable phosphor sheet of the present invention is used for a radiation image recording / reproducing method of a double-side reading system, it is not preferable to provide such a reflective layer.

By providing the above-mentioned reflective layer, the sensitivity of the stimulable phosphor sheet can be further increased. As the reflective layer, for example, a layer formed by dispersing and supporting a white pigment such as titanium dioxide, alumina, or barium sulfate or a phosphor particle not exhibiting stimulated emission with a binder can be used. The stimulable phosphor sheet of the present invention is preferably provided on a support, but the reflective layer is usually provided between the support and the stimulable phosphor sheet.
On the other hand, an excitation light absorbing layer may be provided between the support and the stimulable phosphor sheet instead of the light reflecting layer. This case is particularly advantageous for forming a radiation image with high sharpness.

It is preferable to provide a protective film on the surface of the stimulable phosphor sheet opposite to the support. This protective film is desirably transparent so as to hardly affect the incidence of excitation light and the extraction of photostimulated light, and the photostimulable phosphor should be protected from external physical shocks and chemical influences. It is desirable that the sheet be chemically stable and have high physical strength so that the sheet can be sufficiently protected.

As the protective film, a separately prepared plastic film is adhered to the surface of the stimulable phosphor sheet using an adhesive, or a protective film material solution is applied to the surface of the stimulable phosphor sheet, and then dried. It can be attached to the surface of the stimulable phosphor sheet by utilizing the method described above. A fine particle filler can be added to the protective film in order to reduce interference unevenness and further improve the image quality of the obtained radiographic image. Preferred resin materials for the production of light-transmitting plastic films include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, and cellulose ester derivatives such as cellulose triacetate, and various resin materials such as polyolefin and polyamide. Can be used.
The thickness of the protective film is usually 30 μm or less, preferably 1 to 15 μm.
μm, and more preferably 5 to 12 μm.

It is preferable to provide a fluororesin coating layer on the surface of the protective film in order to enhance the contamination resistance of the protective film.
The fluororesin coating layer can be formed by applying a fluororesin solution prepared by dissolving (or dispersing) a fluororesin in an organic solvent on the surface of the protective film and drying. The fluororesin may be used alone, but is usually used as a mixture of the fluororesin and a resin having a high film forming property. Further, an oligomer having a polysiloxane skeleton or an oligomer having a perfluoroalkyl group can be used in combination. The application of the fluororesin solution can be performed by using a general application means such as a doctor blade, a roll coater, and a knife coater. The fluororesin coating layer may be filled with a fine particle filler in order to reduce interference unevenness and further improve the quality of the obtained radiographic image. The thickness of the fluororesin coating layer is usually 0.5 to 20 μm, preferably 1 to 5 μm. In forming the fluororesin coating layer, additional components such as a crosslinking agent, a hardening agent, an anti-yellowing agent and the like can be used. In particular, the addition of a crosslinking agent is advantageous for improving the durability of the fluororesin coating layer.

In the radiation image recording / reproducing method using the stimulable phosphor sheet of the present invention, a condensing method used for reproducing a recorded image is a conventional one-sided condensing method (a method of condensing light from an excitation light incident surface). Alternatively, both methods of condensing light from the surface opposite to the excitation light incident surface) may be used, or a double-sided light condensing method may be used. It is particularly advantageous when the stimulable phosphor sheet of the invention is used. Next, a radiation image recording / reproducing method by a double-sided condensing method using the stimulable phosphor sheet of the present invention will be described with reference to FIG.

First, a subject is arranged between a radiation source such as X-rays and a stimulable phosphor sheet using a radiation imaging apparatus (not shown) or the like, and then the subject is irradiated with radiation emitted from the radiation source. Then, the radiation transmitted through the subject is made incident on the stimulable phosphor sheet, and the stimulable phosphor of the sheet absorbs and accumulates the energy of the radiation. As a result, a radiation image of the subject is recorded as a latent image on the stimulable phosphor sheet. When the subject itself emits radiation such as β-rays, it is not necessary to use a radiation source.

Next, a radiation image of a subject (or a subject) is read from the stimulable phosphor sheet using a radiation image reading device. FIG. 11 of the accompanying drawings is a schematic cross-sectional view showing an example of the configuration of a reading apparatus used in the dual-side focusing type radiation image recording / reproducing method of the present invention.

In FIG. 11, the stimulable phosphor sheet 20
Is transported in the apparatus by a pair of nip rollers 22a and 22b. Here, the stimulable phosphor sheet 20 is
It has a structure in which a support is provided on the lower surface of the stimulable phosphor sheet as shown in (2) of FIG. 2 and a protective film is provided on the upper surface. Excitation light 23 such as a laser beam is irradiated from the upper surface of the stimulable phosphor sheet
Stimulated light emitted from inside travels to the upper and lower surfaces,
Of these, the stimulating light 24a that has proceeded to the lower surface side of the sheet 20
Is condensed by a condensing guide 25a provided below, is converted into an electric signal by a photoelectric conversion device (photomultiplier) 26a provided at a base of the condensing guide 25a, and is amplified by an amplifier 27a. It is sent to the processing device 28. On the other hand, the stimulated emission light 24b that has proceeded to the upper surface side of the sheet 20 is directly or reflected by the mirror 29 and is collected by the light collection guide 25b provided above, and is provided at the base of the light collection guide 25b. Is converted into an electric signal by the photoelectric conversion device (photomultiplier) 26b,
The signal is amplified by the amplifier 27b and sent to the signal processing device 28.
The signal processing device 28 performs an arithmetic process such as an addition process or a subtraction process, which is predetermined based on the type of the target radiographic image, on the electric signals sent from the amplifiers 27a and 27b. Is sent out as an image signal.

Next, the sent image signal is reproduced as a visible image by an image reproducing device (not shown). The reproducing device may be a display device such as a CRT, a recording device that performs optical scanning recording on a photosensitive film, or for that purpose, temporarily stores an image signal in an image file such as an optical disk or a magnetic disk. It may be replaced by a device.

On the other hand, the stimulable phosphor sheet 20 is sequentially moved in the direction of the arrow by the nip rollers 22a and 22b, and the area subjected to the reading step is then moved to the erasing light source 30 such as a sodium lamp or a fluorescent lamp. It is subjected to an erasing process to be used. As a result, the radiation energy remaining on the sheet after the reading step is released and removed, and the latent image due to the remaining radiation energy is not adversely affected in the next radiation image recording (photographing) step. .

When a recorded image is reproduced in the radiation image recording / reproducing method using the stimulable phosphor sheet of the present invention, a stimulable phosphor sheet on which radiation image information is accumulated and recorded as a latent image as described below. While transferring the excitation light in the plane direction of the stimulable phosphor sheet or moving the excitation light irradiation device in the plane direction of the stimulable phosphor sheet, the excitation light is linearly applied to the stimulable phosphor sheet in a direction orthogonal to the transfer direction. Irradiating the radiation image information by sequentially and one-dimensionally photoelectrically detecting the stimulating light emitted from the latent image of the excitation light irradiated portion of the stimulable phosphor sheet to obtain the radiation image information as an electric image signal A reading method can also be used.

Next, a method for reading radiation image information utilizing the above-described sequential one-dimensional photoelectric detection will be described with reference to FIG.
This will be described with reference to FIGS.

FIG. 12 is a perspective view showing an image information reading apparatus used in the above-mentioned radiation image information reading method.
Is a front sectional view thereof, and FIG. 14 is a side sectional view thereof.

In FIG. 12, the stimulable phosphor sheet 11
No. 0 has a structure in which a support is provided on a lower surface thereof, while a protective film and a multilayer filter (described later) are provided on an upper surface thereof, and radiation such as X-rays transmitted through a subject is irradiated. For example, a radiation image of a subject is accumulated and recorded as a latent image. This stimulable phosphor sheet 110
Are transfer means 111, 11 comprising two sets of nip rollers
2 transports in the direction of arrow Y. On the other hand, the light 115 in the ultraviolet region emitted from the fluorescent lamp 113 enters the surface 114a of the fluorescent light guide sheet 114 disposed on the lower surface thereof and is absorbed. Further, of the light 115 in the ultraviolet region emitted from the fluorescent lamp 113, the light directed upward is also reflected by the reflection plate 1.
The surface 11 of the fluorescent light guide sheet 114 reflected by
4a.

The fluorescent light guide sheet 114 is formed by dispersing a fluorescent substance in a plastic sheet. As the fluorescent substance, the light 1 in the ultraviolet region emitted from the fluorescent lamp 113 is used.
Those that absorb 15 and emit mainly fluorescence 117 having a wavelength of about 600 nm are used. Specific examples of the phosphor include:
Organic phosphors such as coumarin derivatives, thioxanthene derivatives, perylene derivatives, and polone derivatives can be mentioned. Such a fluorescent light guide sheet is sold, for example, by Bayer Japan under the trade name "LISA-plastic". In the present invention, a reflection member 121 made of aluminum or the like is provided on each end face of the fluorescent light guide sheet 114 except for one end face 114b by vapor deposition or the like.
The phosphor excited by the ultraviolet light 115 incident from the light guide 4a emits fluorescent light 117, and the fluorescent light 117 repeats total reflection inside the fluorescent light guide sheet 114 and concentrates with high intensity from one end surface 114b of the lower part of the sheet. Outgoing light. In addition, as the reflection member 121, a metal thin plate, a white paint, or the like can be used in addition to the metal deposition film. Further, the reflection member 121 may be provided also on the back surface (the surface opposite to the front surface 114a) of the fluorescent light guide sheet 114.

The fluorescent light 117 emitted from one end surface 114b of the fluorescent light guide sheet 114 is incident on the stimulable phosphor sheet 110 in a direction substantially perpendicular to the stimulable phosphor sheet 110 (that is, at an incident angle of about 0 °). 110 will be irradiated linearly.
At this time, the direction of the line irradiation is the stimulable phosphor sheet 110.
Is substantially orthogonal to the transfer direction Y. Since the fluorescent light 117 is in the excitation wavelength region of the stimulable phosphor in the stimulable phosphor sheet 110, the stimulable phosphor sheet 1
The area 10 emits stimulated emission light 118 corresponding to the accumulated radiation energy level (ie, carrying radiation image information recorded as a latent image).

At this time, the fluorescence (excitation light) 117 incident on the stimulable phosphor sheet 110 at an incident angle of about 0 ° has a transmittance of 90%.
%, The light satisfactorily passes through the multilayer filter, reaches the stimulable phosphor sheet 110 including the stimulable phosphor-containing partition walls and the stimulable phosphor-filled region, and excites the stimulable phosphor. Excitation light 117 that has been irregularly reflected on the surface of the stimulable phosphor sheet 110 and returned to the multilayer filter side also enters the multilayer filter at various incident angles, but is reflected at a high reflectance, and is again stimulable phosphor. When the sheet 110 is reached, the stimulable phosphor is excited. That is, the excitation light 117 is confined between the multilayer filter and the stimulable phosphor sheet 110, and is effectively used for exciting the stimulable phosphor.
On the other hand, of the stimulable luminescent light 118 emitted from the stimulable phosphor sheet 110, the upwardly directed light is incident on the multilayer filter, but nearly 100% is reflected regardless of the incident angle, and Line sensor 120 arranged below
Will be made incident.

The stimulated emission light 118 enters the line sensor 120 via a selective filter 119 that absorbs the fluorescent light 117 as the excitation light and transmits only the stimulated emission light.
As shown in detail in FIGS. 14 and 15, the line sensor 120 has a light receiving element array 120B divided into pixels fixed to a support 120A extending in the width direction of the stimulable phosphor sheet 110. The light receiving element array 120B is
A large number of solid-state photoelectric conversion elements 120b are arranged and arranged in the width direction of 0, each corresponding to one pixel, and the stimulated emission light 118 is simultaneously received by these solid-state photoelectric conversion elements 120b. The fluorescent light 117 that has passed through the stimulable phosphor sheet 110 is absorbed by the filter 119 and is not received by the solid-state photoelectric conversion element 120b. Each element 120b that has received the light generates a photocarrier and temporarily stores a signal obtained by the photocarrier. The stored signals are sequentially read out by the scanning circuit 130, and the reading of the image information of one linear irradiation portion (corresponding to a scanning line) is completed.

Next, the stimulable phosphor sheet 110 is moved by the nip rollers 111 and 112 to the fluorescent light guide sheet 11.
4 and the line sensor 120 are moved in the direction of the arrow Y by one scan, and the above reading operation is repeated. By repeating this operation for the entire surface of the stimulable phosphor sheet 110, the radiation image information recorded on the stimulable phosphor sheet 110 is read.

Next, the scanning circuit 130 connected to the line sensor 120 will be described. FIG. 15 is an equivalent circuit of a line sensor and a scanning circuit using a photoconductor. A signal generated by photocarriers generated when the photostimulated light 118 is applied to the solid-state photoelectric conversion element 120b using the photoconductor in the line sensor 120 is output from a capacitor Ci (i = 1, 2,... N) in the photoconductor 120b. ). The accumulated photocarrier signal is transmitted to the switch unit 1 controlled by the shift register 131 in the scanning circuit 130.
32 are sequentially read and opened by sequentially opening and closing, whereby a time-series image signal can be obtained. The image signal is
Thereafter, the signal is amplified by the amplifier 133 and output from the output terminal 134. Using this image signal, for example, a CRT
A hard copy of the radiation image can be obtained by displaying the radiation image on a computer or by using a scanning recording device. The MOS section including the shift register 131 and the switch section 132 may be replaced with a CCD.

In the above, the stimulable phosphor sheet 110
The excitation light source composed of the fluorescent lamp 113 and the fluorescent light guide sheet 114 for line excitation of the light may be replaced with, for example, a red cold cathode fluorescent lamp and a reduction optical system such as a slit, or an ultraviolet light emitting fluorescent light. A combination of a lamp, a fluorescent light guide sheet, and a Selfoc lens array may be used. Further, instead of the fluorescent lamp 113, a sodium lamp, a mercury lamp, an electroluminescent panel, or the like can be used.

As a means for detecting a line, instead of the above-mentioned filter 119 and the line sensor 120, an optical fiber (a linear stimulable luminescent light is converted into a planar light) adhered to a stimulable phosphor sheet 110 is used. Using a combination of a filter, a lens, and an area sensor, or a combination of an optical fiber, a filter, a selfoc lens array, and a line sensor, or a combination of a selfoc lens array, a filter (selfoc lens array), and a line sensor Is also good. In the line detection, it is also possible to detect stimulated emission light from a phosphor-filled region group in which a single pixel is linearly arranged in a line, but if necessary, two lines or three or more lines The stimulated emission light can be collectively collected from the phosphor-filled region group.

The transfer means 111 and 112 used for transferring the stimulable phosphor sheet 110 are not limited to the nip rollers, and the transfer means 111 and 112 can be used without disturbing the arrangement of the excitation light source and the light detection means. May be any as long as can be moved by one scan.

Further, the line sensor 120 can be arranged on the same side of the stimulable phosphor sheet 110 as the fluorescent light guide sheet 114. In this case, it is desirable to use a stimulable phosphor sheet without a multilayer filter.

The stimulable phosphor sheet used in the above-described method for reading a radiation image information utilizing photoelectric detection in a one-dimensional manner is applied to the excitation light on the surface of the protective film in order to increase the utilization efficiency of the excitation light. It is desirable to provide a multilayer filter whose reflectivity increases as its incident angle increases and whose reflectivity for stimulated emission light is high irrespective of its incident angle. The multilayer filter is formed by sequentially laminating several to several tens of layers of two or more substances having different optical refractive indexes with a thickness of about 等 of the wavelength of light by vacuum deposition or the like. At this time, various characteristics including the above-described characteristics can be provided by appropriately setting the light refractive index and the layer thickness of each layer. Here, examples of the substance having a low refractive index include SiO ₂ and MgF ₂ . Examples of the substance having a high refractive index include TiO ₂ , ZrO ₂ , and Zn.
S can be mentioned. Alternatively, a multilayer filter may be provided directly on the stimulable phosphor sheet also as a protective film.

Specifically, the multilayer filter is, for example,
Wavelengths 630 to 65 corresponding to the excitation wavelength when the incident angle is 0 °
The band-pass filter has a transmittance of about 90% for light in the range of 0 nm and a transmittance of about 0% for light of other wavelengths, and has an increased incident angle for light in the range of 630 to 650 nm. The transmittance gradually decreases, and the transmittance becomes almost 0% at an incident angle of 50 °. Since the multilayer filter hardly absorbs light, a transmittance of 0% means a reflectance of almost 100%. Therefore, as will be described later, the excitation light incident at an incident angle close to 0 ° passes through the multilayer filter with a transmittance of about 90% and reaches the stimulable phosphor sheet to excite the stimulable phosphor. I do. Excitation light that has been irregularly reflected on the surface of the stimulable phosphor sheet and returned to the multilayer filter side is reflected at a high reflectance and reaches the sheet again. On the other hand, of the photostimulated light emitted from the photostimulable phosphor sheet, nearly 100% of the light that has been directed upward is reflected by the multilayer filter and travels downward of the sheet. With the provision of the multilayer filter, the amount of stimulated emission light can be increased by effectively using the excitation light, and the stimulated emission light can be detected efficiently. It should be noted that such a multilayer filter is described in detail in JP-A-62-203465.

Next, examples of the present invention and comparative examples will be described. The reflectance described in the examples and comparative examples is
It is a value measured by the following method.

[Measurement of reflectance] Stimulable phosphor film,
A stimulable phosphor sheet or a thin film obtained by slicing an alumina film with a thickness of 30 μm along a plane is placed on a black support (having a transmittance of 0.1% or less at a wavelength of 632.8 nm), and A He-Ne laser beam (wavelength 632.8 nm, corresponding to the secondary excitation wavelength of BaFBr: Eu stimulable phosphor) having a beam diameter narrowed to 5 μm is irradiated vertically on the surface of On the other hand, a 150φ integrating sphere (150-0
901) is used to detect reflected light. The reflectance is shown as a 100% (%) of the measured reflected light with respect to the reflected light when similarly measured using a white standard reflector.

[0066]

EXAMPLES Comparative Example 1 A stimulable phosphor (BaFBr: Eu) having a median diameter of 5 μm and a thermoplastic high molecular weight polyester resin were dispersed in an organic solvent at a weight ratio of 20: 1 to obtain a fluorescent light. After obtaining the body dispersion, this phosphor dispersion is
After coating on the surface of the temporary support having a peelable surface and drying to form a dry film, the dry film was peeled off to obtain a stimulable phosphor sheet (1) having a thickness of about 250 μm.

Comparative Example 2 A stimulable phosphor (BaFBr: Eu) having a median diameter of 5 μm and a thermoplastic high molecular weight polyester resin were dispersed in an organic solvent at a weight ratio of 20: 1 to obtain a phosphor. After obtaining the dispersion, the phosphor dispersion is applied to the surface of a temporary support having a releasable surface, dried to form a dry film, and the dried film is peeled to have a thickness of about 215 μm. Stimulable phosphor sheet (2)
I got

Comparative Example 3 A stimulable phosphor (BaFBr: Eu) having a median diameter of 5 μm and a thermoplastic high molecular weight polyester resin were dispersed in an organic solvent at a weight ratio of 20: 1 to obtain a phosphor. After obtaining the dispersion, the phosphor dispersion is applied to the surface of the temporary support having a peelable surface, dried to form a dry film, and then the dried film is peeled to have a thickness of about 150 μm. Stimulable phosphor sheet (3)
I got

Comparative Example 4 1) A particulate stimulable phosphor (BaF) having a median diameter of 5 μm
Br: Eu) and a thermoplastic high molecular weight polyester resin are dispersed in an organic solvent at a weight ratio of 20: 1 to obtain a phosphor dispersion, and then the phosphor dispersion is temporarily supported with a peelable surface. After being applied to the surface of the body and dried to form a dry film, the dried film is peeled off to have a thickness of about 100 μm.
m of the stimulable phosphor film (1) was obtained. 2) A particulate alumina having a median diameter of 1 μm and an acrylic polymer resin are dispersed in an organic solvent at a weight ratio of 20: 1 to obtain an alumina dispersion.
It was applied to the surface of a temporary support having a peelable surface and dried to form a dry film. The dried film was peeled off to obtain an alumina film having a thickness of about 30 μm. 3) Each of the stimulable phosphor film (1) and the alumina film is cut into a 40 mm × 40 mm square to obtain 350 stimulable phosphor films (1) and an alumina film, respectively. After alternately laminating to a total of 700 layers to obtain a laminate, the laminate is about 1 k
g / cm ² under heating at 100 ° C. for 1 hour,
The laminate block (1) was manufactured by performing a pressure heating treatment. 4) The laminate block (1) is repeatedly sliced with a film thickness of 100 μm along the lamination cross section using a wide-width microtome, so that 200 stimulable phosphor films (2) having a one-dimensional stripe structure are formed. ) Got. 5) 200 sheets of the stimulable phosphor film (2) and 200 sheets of the above-mentioned alumina film are superposed in the same manner as above,
After alternately laminating them to a total of 400 layers to obtain a laminate, the laminate is pressed under a pressure of about 1 kg / cm ² .
The laminate was subjected to a pressure and heat treatment for 1 hour under heating at 100 ° C. to produce a laminate block (2). 6) The laminate block (2) is sliced at a film thickness of 215 μm along a lamination cross section on the side where the end face of the stripe appears using a wide microtome, so that a stimulable fluorescent light having a lattice structure in a planar direction is obtained. A body sheet (4) was obtained.

Example 1 1) A particulate stimulable phosphor (BaF) having a median diameter of 5 μm
Br: Eu), particulate alumina having a median diameter of 1 μm, and a thermoplastic high molecular weight polyester resin in a weight ratio of 40:
After dispersing in an organic solvent at 20: 3 to obtain a phosphor dispersion liquid, the phosphor dispersion liquid was applied to the surface of a temporary support having a peelable surface, and dried to form a dried film. After that, the dried film was peeled off to obtain an alumina-containing stimulable phosphor film (3) having a thickness of about 30 μm. 2) The same method as in Comparative Example 4 except that the alumina film was replaced with the above-mentioned stimulable phosphor film containing alumina (3).
m of the stimulable phosphor sheet (5) was obtained.

Example 2 1) Particulate photostimulable phosphor (BaF having a median diameter of 5 μm)
Br: Eu), particulate alumina having a median diameter of 1 μm, and a thermoplastic high molecular weight polyester resin in a weight ratio of 20:
After dispersing in an organic solvent at 40: 3 to obtain a phosphor dispersion liquid, the phosphor dispersion liquid is applied to the surface of a temporary support having a peelable surface, and dried to form a dried film. Thereafter, the dried film was peeled off to obtain an alumina-containing stimulable phosphor film (4) having a thickness of about 30 μm. 2) The same method as in Comparative Example 4 except that the alumina film was replaced with the alumina-containing stimulable phosphor film (4), and the thickness having a lattice structure in the plane direction was about 215 μm.
m of the stimulable phosphor sheet (6) was obtained.

Example 3 1) A particulate stimulable phosphor (BaF) having a median diameter of 1 μm
Br: Eu) and a thermoplastic high molecular weight polyester resin are dispersed in an organic solvent at a weight ratio of 20: 1 to obtain a phosphor dispersion, and then the phosphor dispersion is mixed with a temporary material having a peelable surface. After coating on the surface of the support and drying to form a dry film, the dried film is peeled off to have a thickness of about 30 μm.
m of the stimulable phosphor film (5) was obtained. 2) A stimulable phosphor sheet (7) having a lattice structure in the plane direction and a thickness of about 215 μm by the same method as in Comparative Example 4 except that the alumina film was replaced with the stimulable phosphor film (5). I got

Example 4 1) A particulate photostimulable phosphor (BaF) having a median diameter of 3 μm
Br: Eu) and a thermoplastic high molecular weight polyester resin are dispersed in an organic solvent at a weight ratio of 20: 1 to obtain a phosphor dispersion, and then the phosphor dispersion is mixed with a temporary material having a peelable surface. After coating on the surface of the support and drying to form a dry film, the dried film is peeled off to have a thickness of about 30 μm.
m of the stimulable phosphor film (6) was obtained. 2) A stimulable phosphor sheet (8) having a lattice structure in a plane direction and a thickness of about 215 μm by the same method as in Comparative Example 4 except that the stimulable phosphor film (6) was used instead of the alumina film. I got

Example 5 1) A particulate photostimulable phosphor (BaF having a median diameter of 5 μm)
Br: Eu) and a thermoplastic high molecular weight polyester resin are dispersed in an organic solvent at a weight ratio of 25: 1 to obtain a phosphor dispersion, and then the phosphor dispersion is mixed with a temporary material having a peelable surface. After coating on the surface of the support and drying to form a dry film, the dried film is peeled off to have a thickness of about 30 μm.
m of the stimulable phosphor film (7) was obtained. 2) A stimulable phosphor sheet (9) having a lattice structure in the plane direction and a thickness of about 215 μm by the same method as in Comparative Example 4 except that the alumina film was replaced with the stimulable phosphor film (7). I got

Example 6 1) A particulate photostimulable phosphor (BaF having a median diameter of 5 μm)
Br: Eu) and a thermoplastic high molecular weight polyester resin are dispersed in an organic solvent at a weight ratio of 30: 1 to obtain a phosphor dispersion, and then the phosphor dispersion is mixed with a temporary material having a peelable surface. After coating on the surface of the support and drying to form a dry film, the dried film is peeled off to have a thickness of about 30 μm.
m of the stimulable phosphor film (8) was obtained. 2) A stimulable phosphor sheet (10) having a lattice structure in a plane direction and a thickness of about 215 μm by the same method as in Comparative Example 4 except that the stimulable phosphor film (8) was used instead of the alumina film. I got

Example 7 1) Particulate stimulable phosphor (BaF) having a median diameter of 5 μm
Br: Eu), ultramarine blue particles, and a thermoplastic high molecular weight polyester resin are dispersed in an organic solvent at a weight ratio of 40: 0.2: 3 to obtain a phosphor dispersion liquid. After coating on the surface of the temporary support having a peelable surface and drying to form a dry film, the dried film is peeled off to obtain an ultramarine blue containing stimulable phosphor film (9) having a thickness of about 30 μm. Obtained. 2) A stimulable phosphor sheet (11) having a lattice structure in the plane direction and a thickness of about 215 μm by the same method as in Comparative Example 4 except that the alumina film was replaced with the stimulable phosphor film (9). I got

The structures and reflectances of the alumina film and the stimulable phosphor film used in the production of the stimulable phosphor sheets of the above Comparative Examples and Examples and the stimulable phosphor sheet were as follows. The results are shown in Table 2 and Table 2.

[0078]

[Table 1] Table 1-Stimulable phosphor sheet and Structure Reflectivity 比較 Comparative Example 1 Stimulable phosphor sheet (1 85.0% Comparative example 2 Stimulable phosphor sheet (2) 85.0% Comparative example 3 Stimulable phosphor sheet (3) 85.0% Comparative example 4 Stimulable phosphor sheet (4) Brightness Depleted phosphor film (1) 85.0% Partition walls: Alumina film 88.2% ────────────────────────────── ──────

[0079]

[Table 2] Table 2 ──────────────────────────────────── Stimulable phosphor sheet and Configuration Reflectivity 例 Example 1 Stimulable phosphor sheet (5 ) Stimulable phosphor film (1) 85.0% Partition walls: Stimulable phosphor film (3) 86.1% Example 2 Stimulable phosphor sheet (6) Stimulable phosphor film (1) 85.0% Partition walls: stimulable phosphor film (4) 87.2% Example 3 Stimulable phosphor sheet (7) Stimulable phosphor film (1) 85.0% Partition walls: stimulable phosphor Body film (5) 88.3% Example 4 Stimulable phosphor sheet (8) Stimulable phosphor film (1) 85.0% Partition wall: Stimulable phosphor film (6) 87.4% Implemented Example 5 Photostimulable firefly Light sheet (9) Stimulable phosphor film (1) 85.0% Partition wall: Stimulable phosphor film (7) 86.0% Example 6 Stimulable phosphor sheet (10) Stimulable phosphor Body film (1) 85.0% Partition wall: Stimulable phosphor film (8) 87.0% Example 7 Stimulable phosphor sheet (11) Stimulable phosphor film (1) 85.0% Partition wall : 81.0% photostimulable phosphor film (9)

[Measurement of Sharpness and Sensitivity of Stimulable Phosphor Sheet] (1) Measurement of Sharpness An X-ray having a tube voltage of 80 kVp was applied to a stimulable phosphor sheet of a sample via an MTF (modulation transfer function) chart. After irradiating 10 mR, a He-Ne laser beam (wavelength: 632.8 n
m), the photostimulated light emitted from the excited photostimulable phosphor sheet was received by a photodetector (a photomultiplier having a spectral sensitivity of S-5). This received light is converted into an electric signal,
Based on this, a radiation image was obtained on the display device by the image generation device. The modulation transfer function (M
TF) is measured, and this is converted to a spatial frequency of 2 cycles / mm.
(Lp / mm). Table 3 shows the obtained spatial frequencies.

(2) Measurement of Sensitivity (PSL Sensitivity) The stimulable phosphor sheet of the sample was irradiated with X-rays at a tube voltage of 80 kVp, and then irradiated with a He-Ne laser beam (wavelength: 63).
2.8 nm), and the amount of stimulated emission light (stimulated emission amount) generated from the excited stimulable phosphor sheet is measured.
The stimulated emission was obtained as a relative value. Table 3 shows the relative values of the obtained stimulating light emission amounts. FIG. 16 is a graph showing the relationship between the sharpness and the sensitivity of each stimulable phosphor sheet.

[0082]

[Table 3] Table III Example / Comparative Example Phosphor Sheet Sharpness Sensitivity (MTF) (PSL) 比較 Comparison Example 1 Photostimulable phosphor sheet (1) 50 73 Comparative Example 2 Photostimulable phosphor sheet (2) 52 68 Comparative Example 3 Photostimulable phosphor sheet (3) 56 59 Comparative Example 4 Photostimulable phosphor sheet (4) 6349──────────────────────────────────── Example 1 Stimulable phosphor sheet (5) 57 61 Example 2 Stimulable phosphor sheet (6) 61 54 Example 3 Stimulable phosphor sheet (7) 63 65 Example 4 Stimulable phosphor sheet (8) 58 66 Example 5 Stimulable phosphor sheet (9) 54 69 Example 6 Stimulable phosphor sheet (10) 55 70 Example 7 Stimulable phosphor sheet (11) 55 65 ───────────────────

Embodiments 1 to 9 summarized as a graph in FIG.
Comparing the stimulable phosphor sheet according to the present invention of No. 7 with the stimulable phosphor sheets of Comparative Examples 1 to 4, the spot indicating the relationship between the sharpness and the sensitivity of the former is generally shifted to the upper right side. Therefore, it can be seen that the stimulable phosphor sheet according to the present invention is superior to a known stimulable phosphor sheet as a comprehensive evaluation in consideration of the balance between sharpness and sensitivity.

[0084]

The stimulable phosphor sheet of the present invention emits stimulating light from the latent image by irradiating excitation light after recording a radiation image as a latent image, When used in a radiation image recording / reproducing method that reproduces a radiation image by electrically processing emitted light, an excellent radiation image is given in a comprehensive evaluation in consideration of the balance between sensitivity and sharpness. Therefore, the stimulable phosphor sheet of the present invention is particularly advantageous when used in a method for recording and reproducing a radiation image for medical diagnosis.

[Brief description of the drawings]

FIG. 1 (1) is a perspective view showing a configuration of a stimulable phosphor sheet of the present invention. (2) is a partially enlarged view of the stimulable phosphor sheet of (1), and (3) is (2)
FIG. 2 is a partial cross-sectional view taken along line II of FIG.

FIG. 2A is a cross-sectional view showing another example of the configuration of the stimulable phosphor sheet of the present invention, and FIG. 2B is a sectional view of the stimulable phosphor sheet having the configuration of FIG. A support is provided on the side surface,
It is sectional drawing which shows the state in which the protective film was provided in the upper surface.

FIGS. 3 (1), (2) and (3) respectively show a combination of a stimulable phosphor-containing partition and a stimulable phosphor-filled region constituting a stimulable phosphor sheet of the present invention. It is a perspective view which shows a different aspect typically.

FIG. 4 is a view for explaining a method for producing the stimulable phosphor sheet of the present invention by a lamination slice method, wherein a phosphor film serving as a stimulable phosphor-filled region material and a stimulable phosphor-containing partition wall material, respectively; It is a figure showing a manufacturing process of A and B.

FIG. 5 is a view showing a manufacturing process of a stimulable phosphor sheet laminate from the phosphor films A and B of FIG.

FIG. 6 is a view showing a process of manufacturing a stimulable phosphor laminate block from the stimulable phosphor sheet laminate of FIG. 5;

FIG. 7 is a view showing a step of manufacturing a striped phosphor film from the stimulable phosphor laminate block of FIG. 6 (a slice step of the laminate block).

FIG. 8 is a view showing a stripe phosphor film obtained by slicing the laminate block of FIG. 7;

FIG. 9 is a diagram showing a manufacturing process of a laminate of the stripe phosphor film of FIG. 8 and a phosphor film B as a partition member.

10 is a view showing a slicing step of obtaining a stimulable phosphor sheet having a lattice structure in a planar direction according to the present invention from the stimulable phosphor laminate of FIG. 9;

FIG. 11 is a schematic cross-sectional view showing an example of the configuration of a reading device using a stimulable phosphor sheet of the present invention in a double-sided focusing system.

FIG. 12 is a perspective view showing an image reading apparatus used for a radiation image information reading method using a line sensor.

FIG. 13 is a schematic front view showing a main part of the apparatus of FIG.

FIG. 14 is a schematic side view showing a main part of the apparatus of FIG.

FIG. 15 is a circuit diagram showing a scanning circuit used in the device of FIG.

FIG. 16 is a graph showing a relationship between sharpness and sensitivity in the stimulable phosphor sheet of the example and the stimulable phosphor sheet of the comparative example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 stimulable phosphor sheet 11 stimulable phosphor-containing partition 12 stimulable phosphor-filled region 13 support 14 protective film 20 stimulable phosphor sheet 22 a, 22 b nip roller 23 excitation light 24 a, 24 b stimulable emission light 25a, 25b Condensing guide 26a, 26b Photoelectric converter 27a, 27b Amplifier 28 Signal processor 29 Mirror 30 Erase light source 110 Stimulable phosphor sheet 111, 112 Transport means 113 Fluorescent lamp 114 Fluorescent light guide sheet 115 Light 116 Reflector 117 Fluorescence (excitation light) 118 Stimulated emission light 119 Filter 120 Line sensor 130 Scanning circuit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Katsuhiro Koda 798- Address Miyagidai, Kaisei-cho, Ashigara-gun, Kanagawa Prefecture (72) Inventor Yasuo Iwabuchi 798 Miyagidai, Kaisei-cho, Ashigagami-gun, Kanagawa Fuji Photo Film Inside (72) Inventor Hiroshi Matsumoto 798, Miyagi, Kaisei-cho, Ashigara-gun, Kanagawa Fuji Photo Film Co., Ltd. (72) Inventor Seiji Tazaki 798, Miyadai, Kaisei-cho, Ashigara-gun, Kanagawa Fuji Photo Film Co., Ltd. Terms (reference) 2G083 AA03 CC02 CC06 CC10 DD06 DD11 DD20 EE02 EE03 2H013 AC03

Claims (22)

[Claims] 1. After recording a radiation image as a latent image, the latent image is irradiated with excitation light to emit photostimulated light, and then the photostimulated light is electrically processed to emit radiation. A stimulable phosphor sheet used for a radiation image recording / reproducing method comprising reproducing an image, wherein the stimulable phosphor sheet contains a stimulable phosphor that subdivides the sheet along a plane direction. The partition wall is partitioned by the stimulable phosphor-containing partition wall, and comprises a stimulable phosphor-filled region showing different reflection characteristics from the stimulable phosphor-containing partition wall with respect to the excitation light. Stimulable phosphor sheet. 2. The stimulable phosphor sheet according to claim 1, wherein the stimulable phosphor-filled region has a higher reflectance to excitation light than the stimulable phosphor-containing partition. 3. The stimulable phosphor sheet according to claim 1, wherein the stimulable phosphor-filled region has a lower reflectance to excitation light than the stimulable phosphor-containing partition. 4. The method according to claim 1, wherein a support is provided on one side and a transparent protective film is provided on the other side.
4. The stimulable phosphor sheet according to any one of Items 1 to 3. 5. The stimulable phosphor-filled region and the stimulable phosphor-containing partition both contain at least stimulable phosphor particles and a binder. 3. The stimulable phosphor sheet according to any one of the above items. 6. The stimulable phosphor-filled region is divided by being surrounded by a stimulable phosphor-containing partition wall. Stimulable phosphor sheet. 7. The stimulating light according to claim 1, wherein an excitation light reflecting layer is provided on a surface on a side opposite to a side irradiated with the excitation light. Phosphor sheet. 8. The photostimulable light-emitting device according to claim 1, wherein a photostimulable emission light reflecting layer is provided on a surface on a side opposite to a side irradiated with the excitation light. Stimulable phosphor sheet. 9. The stimulable phosphor-containing partition according to claim 1, wherein the height of the partition wall is in the range of 1/3 to 1/1 of the thickness of the stimulable phosphor sheet. 3. The stimulable phosphor sheet according to any one of the above items. 10. The stimulable phosphor sheet according to claim 1, wherein the stimulable phosphor-containing partition further contains white fine particles. 11. The stimulable phosphor-filled region further contains an excitation light absorbing dye.
The stimulable phosphor sheet according to any one of the above. 12. The stimulable phosphor-containing partition wall further contains an excitation light absorbing dye.
The stimulable phosphor sheet according to any one of the above. 13. The stimulable phosphor-containing partition wall and the stimulable phosphor-filled region are both in the form of fine particles, and are contained in the stimulable phosphor-containing partition wall. The average particle diameter of the stimulable phosphor fine particles is smaller than the average particle diameter of the stimulable phosphor fine particles contained in the stimulable phosphor-filled region. 3. The stimulable phosphor sheet according to any one of the above items. 14. The stimulable phosphor-containing partition wall and the stimulable phosphor-filled region are both in the form of fine particles, and are contained in the stimulable phosphor-containing partition wall. The average particle diameter of the stimulable phosphor fine particles is larger than the average particle diameter of the stimulable phosphor fine particles contained in the stimulable phosphor filled region. 3. The stimulable phosphor sheet according to any one of the above items. 15. The stimulable phosphor-containing partition wall and the stimulable phosphor-filled region both contain at least stimulable phosphor fine particles and a binder, and are contained in the stimulable phosphor-containing partition wall. Wherein the weight ratio of the stimulable phosphor fine particles to the binder is larger than the weight ratio of the stimulable phosphor fine particles contained in the stimulable phosphor-filled region to the binder. A stimulable phosphor sheet according to any one of claims 1 to 13. 16. The stimulable phosphor-containing partition and the stimulable phosphor-filled region are both formed of stimulable phosphor fine particles and a binder, and are included in the stimulable phosphor-containing partition. Wherein the weight ratio of the stimulable phosphor fine particles to the binder is smaller than the weight ratio of the stimulable phosphor fine particles contained in the stimulable phosphor-filled region to the binder. The stimulable phosphor sheet according to any one of claims 1 to 12, and claim 14. 17. The stimulable phosphor sheet according to claim 1, wherein the phosphor sheet is used for light collection on both surfaces. 18. The stimulable phosphor sheet according to claim 1, wherein the stimulable phosphor sheet is irradiated with radiation transmitted through a subject or emitted from a subject. After a radiation image of a subject or a subject is recorded as a latent image on the phosphor sheet, one surface of the stimulable phosphor sheet is irradiated with excitation light, and the stimulable emission light emitted from the latent image is illuminated with the luminescent light. A double-sided condensing type radiation image recording / reproducing method comprising photoelectrically reading from both surfaces of a depleted phosphor sheet, converting it into an image signal, and reproducing a radiation image from the image signal. 19. A stimulable phosphor sheet in which radiation image information is stored and recorded as a latent image on the stimulable phosphor sheet according to claim 1 in a plane direction thereof. The stimulable phosphor sheet is irradiated with the excitation light linearly along the direction perpendicular to the transfer direction while transferring or moving the excitation light irradiation device in the plane direction of the stimulable phosphor sheet. Then, photostimulated emission light emitted from the latent image of the excitation light irradiated portion of the photostimulable phosphor sheet is sequentially and one-dimensionally photoelectrically detected, and the radiation image information is obtained as an electrical image signal. Radiation image information reading method. 20. On the surface of the stimulable phosphor sheet on the side irradiated with the excitation light, the reflectance for the excitation light increases as the incident angle increases, while the reflectance for the stimulable emission light increases. 20. The radiation image information reading method according to claim 19, wherein a stimulable phosphor sheet provided with a multilayer filter independent of an incident angle is used. 21. A fluorescent light-guiding sheet, which is a plastic sheet containing a phosphor and receives light on its surface and emits fluorescent light from one end face thereof, and emits light emitted from a light source. 20. The radiation image information reading method according to claim 19, wherein the irradiation of the excitation light is performed by irradiating the surface with fluorescence emitted linearly from one end face of the stimulable phosphor sheet. . 22. The radiation image information according to claim 19, wherein stimulated emission light is one-dimensionally photoelectrically detected using a line sensor in which a large number of solid-state photoelectric conversion elements are linearly arranged. Reading method.