JPH046936B2 - - Google Patents

Description

Detailed Description of the Invention The present invention provides a sheet that accumulates and records radiation images and efficiently guides stimulated luminescence light emitted when a stimulable phosphor is irradiated with excitation light such as a laser beam to a photodetector. The present invention relates to a support member for a sheet-like light condenser to which the light condenser is attached.

Certain types of fluorophores are exposed to radiation (X-rays, α-rays, β-rays,
When irradiated with γ-rays, ultraviolet rays, etc., a part of this radiation energy is accumulated in the phosphor, and when this phosphor is irradiated with excitation light such as visible light, the phosphor increases depending on the accumulated energy. is known to exhibit stimulated luminescence, and phosphors exhibiting this property are called stimulable phosphors.

Using this stimulable phosphor, radiation image information of the human body, etc. is recorded once on the stimulable phosphor provided on a sheet, and this phosphor sheet is scanned with excitation light such as a laser beam. to generate photostimulated luminescent light, photoelectrically read out the obtained stimulated luminescent light to obtain an image signal,
The applicant has already proposed a radiation image system that outputs a visible image to a recording material such as a photographic light-sensitive material, CRT, etc. based on this image signal. (JP-A-55-12429, JP-A No. 56-11395, etc.) By the way, the light emitted from a stimulable phosphor is non-directional and is itself weak light, so it is important to make the solid angle of reception as large as possible. , it is necessary to collect a lot of light and increase the light collection efficiency. If this light collection efficiency is low, the S/N will decrease, and in the worst case, it will become impossible to even detect a signal.

Therefore, in JP-A No. 55-87970, the present inventors proposed that a light-guiding sheet material be used between a photodetector that detects light emitted from a stimulable phosphor and a stimulable phosphor sheet. a sheet-like light condenser, one end of which is placed adjacent to the scanning line on the stimulable phosphor sheet;
They also proposed that the other end be formed to match the shape of the light-receiving surface of the photodetector and placed adjacent to the light-receiving surface, thereby increasing the light collection efficiency of the received light and improving the S/N ratio.

Here, the sheet-shaped light collector is made by processing a transparent thermoplastic resin sheet such as acrylic resin, and the light that enters from the incident surface is transmitted to the exit surface while being totally reflected inside. The stimulated luminescent light from the stimulable phosphor sheet is guided into the sheet-like light collector, exits from the exit surface, and is received by a photodetector. The preferred shape, material, etc. of the sheet-like light condensing body are described in Japanese Patent Application Laid-open No. 55-87970 and the same.
It is disclosed in Publication No. 56-11397, etc.

Furthermore, as disclosed in JP-A-56-11396, the manufacturing method is to heat and soften one end of a transparent thermoplastic resin sheet such as an acrylic plate while keeping it flat, and to soften the other end. This is achieved by fixing it in a circularly rolled state and allowing it to cool naturally, then cutting both ends and polishing the cut surfaces. Therefore, the shapes of the sheet-like light condensing bodies are different from one another, and there has been a problem in that, in particular, the opening width of the incident end face and the linearity from the incident end face to the exit end face vary. Since the shape of each sheet-like light condenser differs in this way, if the sheet-like light condenser is fixedly supported by clamping it with a clamp member, etc., the laser light will not be irradiated onto the stimulable phosphor. Therefore, it is extremely difficult to maintain a constant light receiving solid angle in the vicinity of the light emitting point and position the incident end face at an optimal position without cutting off the laser beam.

Therefore, an object of the present invention is to make the light-receiving solid angle of the incident end face of a sheet-like light condensing body always constant with respect to the light emitting point, and further to achieve the positioning of the incident end face without cutting off the incident laser beam. There is a particular thing.

In order to achieve this objective, the inventors of the present invention have conducted intensive research and found that a sheet-like light collector is developed in which the incident end surface of the sheet-like light collector is brought into contact with a support member, instead of fixedly supporting the sheet-like light collector. We came up with the idea of a method for holding the light beam, and furthermore, the support member has a vertical support surface that linearly supports the upper edge of the incident end surface of the sheet-like light collector and a horizontal support surface that linearly supports the lower edge of the incident end surface. By configuring the vertical support surface to be approximately parallel to the incident laser beam for exciting the stimulable phosphor and by making the horizontal support surface approximately parallel to the surface of the stimulable phosphor sheet, I have achieved my goal.

According to the present invention, even if there are variations in the shape of the sheet-like light condensing body, a constant light receiving solid angle can always be obtained, and problems such as blocking the incident laser light do not occur.

EMBODIMENT OF THE INVENTION Hereinafter, the support member of the sheet-like light condensing body of this invention is demonstrated in detail, referring to drawings.

FIG. 1 is a schematic perspective view showing a preferred embodiment of the present invention, and FIGS. 2A and 2B are partial side views of FIG. 1, respectively.

As illustrated, the support members 1, 1' in this embodiment have a vertical support surface and a horizontal support surface,
It has an L-shape in which the respective support surfaces intersect at right angles, and the pair of support members 1 and 1' are positioned at both ends of the linear incident end surface 3 of the sheet-like light condenser 2. , and the entrance end surface 3 is disposed parallel to the scanning line 5 formed by the incident laser scanning light 4.
Furthermore, in this embodiment, the laser beam is irradiated onto the stimulable phosphor sheet parallel to the vertical support surface of the support members 1, 1', and the surface of the stimulable phosphor sheet is It is set parallel to the horizontal support surface. An end surface opposite to the incident end surface 3 of the sheet-like light collector 2, that is, an exit end surface 6, is provided with a filter that cuts out light other than the stimulated luminescence light emitted by irradiating the stimulable phosphor with excitation light. A photodetector 7 such as a photomultiplier is fixed to the sheet-like light condensing body 2, and the photodetector 7 is held by a holding member 8 so that the incident end surface 3 is brought into contact with the supporting members 1 and 1'. It's getting old. By doing this, the side part of the upper edge of the entrance end face 3 is connected to the support member 1,
It is line-supported on the vertical support surface of support member 1', and the side part of the lower edge is line-supported on the parallel support surface of support members 1 and 1'.

When the sheet-like light condensing body is supported in this way, for example, the sheet-like light condensing bodies 2A and 2B may be distorted as shown in FIG. Even if the angles with respect to the stimulable phosphor sheet 15 near the entrance end surface do not match, the horizontal position of the upper edge of the entrance end surface is determined by the vertical support surface 1A of the support member 1, and the vertical position of the lower edge of the entrance end surface is determined by the support member. The solid angle of light reception from the light emitting point to the entrance end face opening can always be approximately constant. The stimulated luminescent light emitted from the stimulable phosphor emits diffused light, that is, non-directionally, so the amount of light obtained by the sheet-like light collector remains almost constant even if there is angular deviation as described above, which is good. The light is focused.

In addition, even if there is an imbalance in the aperture width of the incident end face of the sheet-like light condenser as shown in Figure 2B, when the width of the incident end face is wide, the entrance end face is located far from the light emitting point, and the width becomes narrow. Since they are located close to each other, the solid angle of light reception is kept almost constant, and even in such a case, the light collection efficiency is always stable regardless of variations in the shape of the sheet-like light collector.

Furthermore, if the laser beam is made to be incident parallel to and slightly behind the vertical support surface with which the upper edge of the sheet-like light condenser of the support members 1, 1' comes into contact,
The laser beam is not eclipsed by the upper edge of the incident end surface of the sheet-like light condenser.

In a radiation image reading device equipped with a sheet-like light condenser supported as described above, a radiation image accumulated and recorded in a stimulable phosphor is read out, for example, in the following manner.

The laser light 10 emitted from the laser light source 9 is
The diameter of the beam is precisely adjusted by a beam expander 11, and the beam is deflected by an optical deflector 12 such as a galvano mirror, so that it is scanned onto a stimulable phosphor sheet 15 via a plane reflecting mirror 14. Here, the laser light source 9 is selected so that the wavelength range of the laser light 10 does not overlap with the wavelength range of the stimulated luminescent light from the stimulable phosphor sheet 15. Further, an fθ lens 13 is disposed between the optical deflector 12 and the plane reflecting mirror 14, so that the laser beam always scans the stimulable phosphor sheet 15 at a constant speed. Furthermore, main scanning is performed by deflecting the laser beam by the optical deflector 12, and in this embodiment, the stimulable phosphor sheet 15 is
Sub-scanning is performed by mechanically transporting the sheet 15 in the direction, so that the entire surface of the sheet 15 is scanned two-dimensionally. When irradiated with the laser scanning light 4 in this manner, the stimulable phosphor sheet 15 emits stimulated luminescence light in an amount proportional to the radiation energy stored and recorded. Here, this stimulated luminescence light is emitted diffusely and non-directionally. As mentioned above, in this example, the solid angle of acceptance from the light emitting point to the incident end face is kept almost constant even if there are variations in the shape of the sheet-like light collector, and the amount of stimulated luminescence light incident on the incident end face is remains almost constant. The stimulated luminescence light enters the sheet-like light collector 2 from the incident end face, is guided through the sheet-like light collector 2 while repeating total reflection, is emitted from the exit end face, and is received by the photodetector 7. As described above, a filter that selectively transmits only the wavelength range of the stimulated luminescence light is attached to the light receiving surface of the photodetector 7, so that only the stimulated luminescence light is detected by the photodetector 7. This electrical signal is output as an electrical signal, and after being processed through amplification, A/D conversion, image processing, etc., it is recorded or recorded on a photosensitive material.
The radiation image is displayed as a visible image on a CRT or the like.

FIG. 3 is a side view showing another embodiment of the invention.

In this embodiment, the angle between the vertical support surface 20A and the horizontal support surface 20B of the support member 20 is not a right angle but an obtuse angle. The support member 20 is installed so that the horizontal support surface 20B of the support member 20 is parallel to the surface of the stimulable phosphor sheet 15, and the vertical support is placed so that the laser scanning light is approximately parallel to the vertical support surface 20A. The light is made to be incident slightly behind the surface 20A. The sheet-like light condenser 2 is supported by the upper edge of the incident end surface being in line contact with the vertical support surface 20A and the lower edge being in line contact with the horizontal support surface 20B. Even if there are differences in shape, it is possible to always obtain a substantially constant solid angle of light reception, and it is possible to obtain stable and high light collection efficiency, and the incident laser scanning light is not eclipsed.

FIG. 4 shows yet another embodiment of the present invention, and FIG. 5 is a partial side view of FIG. 4.

In this embodiment, the supporting members 21, 21'
are two mutually parallel vertical support surfaces 21A, 21B
and two horizontal support surfaces 21C and 21 having the same height that support this protrusion.
It has a T-shaped cross-sectional shape with a letter D, and the incident end surfaces of the two sheet-like light condensing bodies 2, 2' are supported on both left and right sides of the supporting members 21, 21'. There is. The method of support is similar to the embodiment described above. That is, the upper edge of the incident end surface of the sheet-like light condenser is linearly supported by the vertical support surface, and the lower edge is linearly supported by the horizontal support surface. Further, the laser scanning light 4 is transmitted to two vertical support surfaces 21A and 21B.
The horizontal support surfaces 21C and 21D are parallel to the surface of the stimulable phosphor sheet. Also in this embodiment,
As described based on each of the above embodiments,
The solid angle of light reception from the light emitting point is kept almost constant, and high light collection efficiency can be stably obtained. Further, the laser scanning light 4 is also applied to each sheet-like light condenser 2,
It is not eclipsed by the upper edge of the incident end face of 2'.

In this way, the two sheet-like light collectors collect the stimulated luminescent light emitted from the stimulable phosphor,
By detecting light with two photodetectors 7 and 7', the light collection efficiency is twice as high as when using a single sheet-like light collector and photodetector. A high S/N ratio can be obtained, and good signal detection can be performed.

Note that as another method for obtaining twice the light collection efficiency, Japanese Patent Laid-Open No. 11398/1983 by the present applicant shows the use of a reflective mirror, but even in this case, the method shown in FIG. It goes without saying that the supporting members 21 and 21' can be used as positioning supporting members for the reflecting mirror 16.

Examples will be given below to further clarify the effects of the present invention.

The dependence of the light collection efficiency on the inclination angle of the sheet-like light collector when using the support member of the present invention was measured.

FIG. 7 is a graph showing the dependence of light collection efficiency on the inclination angle of the sheet-like light collector when the supporting material of the present invention is used.

Here, the inclination angle of the sheet-like light collector is defined as the angle θ (degrees) between the lower surface near the incident end surface of the sheet-like light collector and the horizontal support surface of the support member. Measurement angle is 35°~
It was 75°.

As shown in Figure 7, the inclination angle is 35° to 60°.
It was found that almost constant and high light collection efficiency could be obtained even when the light was changed.

In addition, the dependence of the light collection efficiency on the distance between the laser scanning light and the vertical support surface of the support member was measured.

FIG. 8 is a graph showing the dependence of the light collection efficiency on the distance between the laser scanning light and the vertical support surface of the support member when the support member of the present invention is used. (The measurement range was 0.5 to 1.5 mm.) As shown in FIG. 8, it was found that the focusing efficiency was higher when the laser scanning light was brought as close to the vertical support surface as possible. Therefore, in the case of a T-shaped support member capable of supporting two sheet-like light collectors, it is desirable to minimize the distance between the two vertical support surfaces.

As explained above in detail, by using the support member of the present invention, even if there are variations in the shape of the sheet-like light collector, it is possible to always obtain a constant high light collection efficiency, and also to There are no problems such as lighting problems.

The support member of the present invention is particularly effective when detecting weak light in small areas in order to read radiographic images used for diagnosis such as stimulable phosphor sheets with high resolution as described above. . The support member of the present invention is also effective in detecting emitted light or reflected light by optically scanning a sheet below the stimulable phosphor.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing a preferred embodiment of the present invention, FIGS. 2A and 2B are partial side views of FIG. 1, and FIG. 3 is a side view showing another embodiment of the present invention. , FIG. 4 is a perspective view showing still another embodiment of the present invention, FIG. 5 is a partial side view of FIG. 4,
FIG. 6 is a partial side view of the embodiment shown in FIG. 4 in which a single sheet-like light condenser and reflecting mirror are supported, and FIG. 7 is a light condensing body in the case of using the supporting member of the present invention. FIG. 8 is a graph showing the dependence of the efficiency on the inclination angle of the sheet-like light condensing body, and FIG. This is a graph showing. 1, 1', 20, 21, 21'...Supporting member, 1
A, 20A, 21A, 21B... Vertical support surface, 1
B, 20B, 21C, 21D...Horizontal support surface,
2, 2'...Sheet-like light condenser, 3...Incidence end surface,
4...Laser scanning light, 5...Scanning line, 6...Emission end face, 7, 7'...Photodetector, 8, 8'...Holding member, 9...Laser light source, 10...Laser light, 11
... Beam expander, 12 ... Optical deflector, 1
3... fθ lens, 14... plane reflecting mirror, 15...
stimulable phosphor sheet, 16... reflective mirror;

Claims (1)

[Scope of Claims] 1. Luminescence that is emitted along the scanning line of laser light when a laser scanning light is irradiated onto a stimulable phosphor sheet that has a linear incident end face and that stores and records radiation images. A support member for a sheet-like light condenser that supports a light-guiding sheet-like light condenser that guides emitted light from the incident end face to the exit end face with the incident end face along the scanning line. The sheet-like light condenser has a vertical support surface that linearly supports the upper edge of the incident end surface, and a horizontal support surface that linearly supports the lower edge of the incident end surface, and the vertical supporting surface is substantially parallel to the incident laser beam. A support member for a sheet-like light concentrator, wherein the support member is parallel, and the horizontal support surface is substantially parallel to the surface of the stimulable phosphor sheet. 2. Claim 1, wherein the angle between the horizontal support surface and the vertical support surface is a right angle.
A support member for a sheet-like light condensing body as described in 2. 3. When a stimulable phosphor sheet having a linear incident end face is irradiated with laser scanning light onto a stimulable phosphor sheet on which a radiation image has been accumulated and recorded, the stimulated luminescent light emitted along the scanning line of the laser light is emitted from the incident end face. A support member for a sheet-like light condenser that supports a pair of light-guiding sheet-like light condensers that guide the light from the light source to the exit end face while facing each other such that the incident end face is along the scanning line, the supporting member a first vertical support surface that linearly supports the upper edge of the incident end surface of one of the sheet-like light condensers; a first horizontal support surface that linearly supports the lower edge of the incident end surface; A second vertical support surface that linearly supports the upper edge of the incident end surface of the other sheet-like light condenser of the pair of sheet-like light condensers, and a second horizontal support surface that linearly supports the lower edge of the incident end surface. the first and second vertical support surfaces are substantially parallel to the incident laser beam, and the first and second horizontal support surfaces are substantially parallel to the plane of the stimulable phosphor sheet. A support member for a sheet-like light condenser, characterized in that it has a generally T-shaped cross-sectional shape as a whole.