JPH03209451A - Radiograph information reader - Google Patents

Abstract

PURPOSE:To use a small-sized photodetector by arranging a condensing optical system for condensing light emitted from a light exit end surface on the incident surface of the photodetector between the light exit end surface of an optical guide and the photodetector. CONSTITUTION:As to the optical guide 4, one end surface 4a' formed of a photoconductive material functions as the incident end surface 4a, and the surface which is obtained by gathering the other end surfaces 4d' functions as the light exit end surface 4d, and a convex lens 6 for condensing the light on the photodetector such as a photomultiplier 5, etc., is jointed on the light exit end surface 4d. And the light emitted from a position scanned with scanning light is efficiently made incident on the incident end surface 4a and also the incident light goes forward in the optical guide 4 with total reflection, and then, the light is satisfactorily transmitted to the light exit end surface 4d. On the other hand, the optical guide 4 is bent so that the light exit end surface may be formed in the plane vertical with reference to the incident end surface, so that the distance in the direction vertical with reference to the incident end surface can be shortened. Then, the efficiency of transmitting the light can be maintained and also the size of it can be made compact. Thus, the small-sized photodetector can be used.

Description

Detailed Description of the Invention (Field of the Invention) The present invention relates to a light guide made of a light-guiding material and transmitting light incident from one end surface to the other end surface, and a photodetector that receives the light emitted from the light guide. The present invention relates to a radiation image information reading device comprising:

(Prior art) It is formed of a light-guiding material, one end surface is placed close to the light emitting position, and the other end surface is connected to a photodetector etc.
A radiation image information reading device consisting of a light guide that transmits light incident from one end surface to the other end surface and a photodetector that receives the light emitted from the light guide is used in various optical devices. A radiation image information recording and reproducing system that has already been proposed by
No. 429.

5B-11395, 55-163472, 5
B-104645.

55-11Ei340, etc.).

In other words, when a certain type of phosphor is irradiated with radiation (X-rays, α-rays, β-rays, γ-rays, electron beams, ultraviolet rays, etc.), part of the second radiation energy is accumulated in the phosphor, and this phosphor is It is known that when irradiated with excitation light such as visible light, the phosphor exhibits stimulated luminescence depending on the accumulated energy.
A phosphor exhibiting such properties is called a stimulable phosphor (stimulable phosphor). The radiation image information recording and reproducing system uses this stimulable phosphor to partially record radiation image information of a subject such as a human body on a sheet of stimulable phosphor, and this stimulable phosphor sheet (hereinafter referred to as (simply referred to as a sheet) is scanned with excitation light such as a laser beam to generate stimulated luminescence light, the resulting stimulated luminescence light is read photoelectrically to obtain an image signal, and based on this image signal, the radiation of the subject is determined. The image is output as a visible image to a recording material such as a photographic light-sensitive material, a CRT, or the like. The above-mentioned light guide is used as a means for transmitting the stimulated luminescence light to a photodetector such as a photomultiplier in the radiation image information reading device constituting the system.

Examples of such a radiation image information reading device comprising a light guide and a photodetector are disclosed in Japanese Patent Laid-Open Nos. 55-87970 and 63-236025.

An example of such a conventional radiation image information reading device is shown in FIG.

Excitation light source] Excitation light 101a of constant intensity emitted from the old
is made incident on an optical deflector such as a galvanometer mirror 102, and by this galvanometer mirror 102,
A stimulable phosphor sheet 10 on which radiation image information is stored and recorded is placed below the galvanometer mirror 102
3 is reflected and deflected so as to main scan (scan in the direction of arrow A) in its width direction.

The stimulable phosphor sheet 103 is attracted onto, for example, an endless belt device 109 and conveyed in the direction of arrow B (
Therefore, the main scanning of the excitation light 101a is repeated in a direction substantially perpendicular to the sub-scanning direction, and the excitation light 101a covers the entire surface of the stimulable phosphor sheet 103.
A dimensional scan is performed.

The part of the stimulable phosphor sheet that is irradiated with the excitation light 101a according to the scanning by the excitation light 101a emits stimulated light according to the image information accumulated and recorded there, and this emitted light is emitted in the vicinity of the stimulable phosphor sheet. Light enters the light guide 104 from the incident end surface 104a of the transparent light guide 104, which has an incident end surface 104a formed parallel to the main scanning line. This light guide 1
04, as shown in FIG. 6, the front end 104b located near the stimulable phosphor sheet 103 is formed into a planar shape, and the sheet gradually becomes cylindrical toward the rear end. The rear end portion 104C has a substantially cylindrical shape and is connected to a photomultiplier 105 provided on the exit end surface 104d. The stimulated luminescent light entering from the incident end face 104a is transmitted through the light guide 104 by total reflection and reaches the rear end 104.
C, and is transmitted to the photomultiplier 105 via a filter (not shown) that selectively transmits the stimulated luminescent light. In the photo multiplier 105,
The stimulated luminescent light is converted into an electrical signal, and the obtained electrical signal is sent to the image information reading circuit 106 and processed, and then output as a visible image to a CRT 107 or recorded on a magnetic tape 108, for example. , or directly recorded as 11-tocoby on photographic materials.

(Problem 8 to be Solved by the Invention) In the radiation image information reading devices described in any of the above-mentioned publications, the end face of the light guide is joined to the photodetector (as disclosed in JP-A No. 63-236025, No. 2). Although the figure shows the two parts separated for explanation, it is clear from the explanation in the text that the two parts are joined.)1. For this reason, the size of the photodetector is determined by the size of the light guide, making it impossible to use a photodetector of any size, especially a small size.

Small photodetectors are not only cost-effective;
Since many of them are stable in terms of performance, it is a practical disadvantage that a small photodetector cannot be used.

Furthermore, since the light guide and the photodetector are fixed to each other, if one of them fails, only one cannot be replaced. In particular, when the performance of the photodetector deteriorates over time, it is not possible to replace the photodetector, which is inconvenient.

Therefore, the present invention can use a small photodetector,
Furthermore, this patent is characterized in that it provides a radiation image information reading device in which the photodetector can be replaced.

(Means for Solving the Problems) The radiation image information reading device of the present invention takes in stimulated luminescence light emitted by excitation light scanning from a stimulable phosphor sheet on which radiation image information is accumulated and recorded, from an incident end face, and emits the emitted light. In a radiation image information reading device comprising a light guide that guides the light to an end surface and emits it, and a photodetector that receives light emitted from the light guide, there is a space between the exit end surface of the light guide and the photodetector, The device is characterized by being provided with a condensing optical system that condenses the light emitted from the exit end surface onto the incident surface of the photodetector.

Various types of condensing optical systems can be used, such as a convex lens, an optical fiber bundle, a concave mirror, or a combination of these and a mirror.

(Functions and Effects) According to the radiation image information reading device described above, a condensing optical system such as a convex lens is provided between the exit end surface of the light guide and the light receiving surface of the photodetector. Since the light can be efficiently focused on the incident surface of the photodetector, a small photodetector can be used.

Furthermore, since the light guide and the photodetector are separated, the photodetector can be easily replaced.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a light guide material for forming a light guide used in a radiation image information reading device according to an embodiment of the present invention, FIG. 2 is a perspective view showing the completed light guide, and FIG.
The figure is a side view showing a radiation image information reading device according to an embodiment of the present invention, which is combined with a condensing optical element and a photodetector.

This light guide 4 can be made, for example, by modifying the light-guiding material 4' shown in FIG. This light guiding material 4
' is made of, for example, a transparent acrylic plate with a uniform thickness t, and one end surface 4a' extends in the linear direction, and is a part 4e' including this one end surface 4a' excluding one end portion 4b'; It is cut into strips in a direction perpendicular to one end surface 4a'. There are, for example, five strip-shaped sections, the width of which is larger at the center and narrower at both ends.

Further, the length 1 of each strip-shaped portion gradually increases from one end to the other end. Such a light guide material 4' becomes a light guide 4 shown in FIG. 2 by bending each of the strip-shaped portions in a direction parallel to the one end surface 4a'. That is, each strip-shaped portion is bent toward the right, which is the side of the shortest strip-shaped portion, and is oriented in a direction parallel to the one end surface, and the rear ends of each are overlapped in the thickness direction. They are bundled, and each other end surface 4d' is connected to the one end surface 4a.
' are adjacent to each other in a plane perpendicular to ' to form one plane. The difference in length 1 of the strip-shaped portions is set in advance so that when the strip-shaped portions are bent, the bending angles of each strip-shaped portion are approximately equal and the other end surfaces 4d' are aligned in the same plane. has been done.

In the light guide 4 formed in this way, as shown in FIG. 2, the one end surface 4a' of the light-guiding material becomes the entrance end surface 4a, and the surface where the other end surface 4d' is assembled becomes the exit end surface 4d. . The entrance end surface 4a is disposed along the main scanning position of the scanning light 4a such as excitation light, similar to the conventional light guide. A photomultiplier is installed on the injection end surface 4d as shown in FIG.
A convex lens 6 for condensing light onto a photodetector such as No. 5 is joined. It should be noted that if the width of the aforementioned strip-shaped portions is made larger toward the center, the shape of the exit end surface 4d will become closer to a circle, which is convenient when joining the circular convex lens 6, but there is no particular problem. In this case, the widths of all the strip-shaped portions may be made equal, and the shape of the injection end surface 4d may be rectangular.

By using the above-mentioned light guide 4, the emitted light (e.g., stimulated emitted light) emitted from the scanning position of the scanning light (e.g., excitation light) can be efficiently transmitted to the incident end face 4a, which can be placed close to the scanning position. Since the light guide 4 is basically made of a sheet-like material with a constant width and thickness, the incident light travels through the interior of the light guide 4 by total reflection and is well reflected at the exit end surface 4d. Reportedly. On the other hand, since the light guide 4 is bent so as to be formed in a plane perpendicular to either the exit end surface or the entrance end surface, the length in the direction perpendicular to the entrance end surface is formed from a single sheet of conventional light guiding material. It can be reduced to about one-half to one-third of a light guide (for example, the one disclosed in Japanese Patent Application Laid-Open No. 55-87970). Therefore, such a light guide maintains the same light transmission efficiency as a conventional light guide made of a sheet-shaped light-guiding material,
Its size can be made compact. Note that most of the light incident on the light-guiding material as described above is transmitted by total reflection, but a small portion of the light is absorbed inside or leaks to the outside every time it is reflected. Therefore, as the optical path length in the light-guiding material increases, the light transmission efficiency decreases little by little. This light guide uses light emitted from a position close to the photo multiplier and
Since there is a difference in the optical path length between the light emitted from a position far away from the incident end surface 4a and the exit end surface 4d, there may be a difference in the light transmission efficiency. Since it is simple and constant over time, it corresponds to the shape of It can be easily corrected. Further, the above-mentioned light guiding material 4' has one end portion 4
b' does not necessarily have to be integral, and may consist entirely of a rectangular portion as shown by the dashed line in FIG. In this case, since a boundary is formed on one end surface serving as the incident end surface, shading occurs in which the light transmission efficiency of light incident on the boundary portion decreases, but this shading can also be corrected electrically. Further, the entrance end face and the exit end face do not have to be strictly perpendicular, and may be formed slightly inclined as long as the length in the direction perpendicular to the entrance end face of the light guide can be reduced.

Furthermore, the light guide of the present invention can be made by cutting, bending, etc. a single sheet of light guide material as described above, or by integrally molding the light guide material into a similar shape. It is also possible to make one.

Note that in order to prevent loss of light quantity on the surface of the convex lens 6 and the light receiving surface of the photodetector 5 as much as possible, it is desirable to coat these surfaces with an antireflection film.

In the embodiment shown in FIG. 3, a filter 7 that selectively transmits only stimulated emission light is attached to the light receiving surface of the photodetector 5 to reduce noise.

Furthermore, the light guide 4 used in the radiation image information reading device of the present invention does not require the use of the light guide material cut into strips as described above, but instead is made of a single sheet-like material as in the conventional format. It may be formed from a light-guiding material. Such an example is shown in FIG.

In FIG. 4, a convex lens 16 is bonded to the exit end surface 14b of a light guide 14 made of a sheet-like light-guiding material, and a photodetector 1 is placed at a position where light is focused by the convex lens 16, which is separate from the convex lens 16.
This shows an example in which the light receiving surface (filter) 17 of No. 5 is positioned.

In each of the above embodiments, the attached lens 6.16 is bonded to the exit end surface of the light guides 4, 14, but this may be an optical fiber or a concave mirror provided at a location away from the exit end surface. Alternatively, a combination of these may be used. In short, any optical means that focuses the light emitted from the exit end faces of the light guides 4 and 14 onto the light receiving surface of the photodetector can be used as the focusing optical system.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a light guide material for forming a light guide used in a radiation image information reading device according to an embodiment of the present invention, FIG. 2 is a perspective view of the light guide, and FIG. 4 is a side view showing a radiation image information reading device according to an embodiment of the present invention, FIG. 4 is a perspective view showing a radiation image information reading device according to another embodiment of the invention, and FIG. 5 is a conventional radiation image information reading device. FIG. 6 is a perspective view showing a light guide used in a conventional radiation image information reading device. 4.14...Light guide 4a, 14a...Incidence end face 4d, 14d...Emission end face 5.15...
・Photodetector 6.16...Condensing optical element

Claims (1)

[Scope of Claims] A light guide that takes in stimulated luminescence light emitted by excitation light scanning from a stimulable phosphor sheet that stores and records radiation image information from an incident end face, guides it to an exit end face, and emits it;
In a radiation image information reading device comprising a photodetector that receives light emitted from the light guide, the light emitted from the emission end surface is detected between the emission end surface of the light guide and the photodetector. A radiation image information reading device comprising a condensing optical system that condenses light onto an incident surface of a device.