JPH07270537A - Radiation image detector - Google Patents

Abstract

PURPOSE:To obtain a compact radiation image detector by providing a solid- state image sensing device so that the plane of incidence of light is opposed to the light output end face, and by lessening the length in the direction of incidence of light of an optical fiber plate. CONSTITUTION:CCD 2 is provided on the light output end face of an optical fiber plate 3 having the light output end face and light incidence end face 31 which intersect the direction of waveguide of light respectively and are orthogonal substantially to each other. Since the end face 31 is coated with a material having a scintillation function, the light generated by a radiation falling on the end face 31 is propagated in the direction of waveguide of the light and, therefore, it is emitted from the light output end face and cast on the plane of incidence of light of the CCD 2. Since the plane of incidence of light of the CCD 2 and the end face 31 are orthogonal substantially to each other, the radiation falling vertically substantially on the end face 31 advances straight in parallel practically to the plane of incidence of light of the CCD 2 and, therefore, the radiation does not fall on the plane of incidence of light of the CCD 2. Besides, the radiation is not guided either by the plate 3 coupling the plane of incidence of light of the CCD 2 with the end face 31 optically.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation image detector used for industrial and medical purposes.

[0002]

2. Description of the Related Art Conventionally, the most common radiation image detector is the radiation image detector shown in FIG. 4A (hereinafter referred to as "prior art 1"). That is, it is common to have an optical fiber plate 103, a solid-state imaging device 102 formed on the light output end surface of the optical fiber plate 103, and a scintillator 104 formed on the light input end surface of the optical fiber plate 103. The optical output end face of the optical fiber plate 103 is the solid-state image sensor 1
It is provided on the light incident surface of No. 02, and both are optically coupled.

In the prior art 1, the radiation transmitted through the scintillator 104 is directly incident on the solid-state image sensor 102, causing damage to the solid-state image sensor 102 and noise.

Therefore, in order to eliminate this defect, FIG.
The radiation image detector shown in (b) (hereinafter referred to as "prior art 2") is formed by bending the core of the optical fiber plate 103, and the radiation image detector shown in FIG. 4 (c) (hereinafter referred to as "prior art 3"). That is, the angle of the core of the optical fiber is not perpendicular to the light incident surface of the solid-state image sensor 102 but is inclined to prevent radiation from entering the solid-state image sensor 102. That is, the prior art 2 is to bend the optical fiber plate 103 to allow the radiation to pass through the core and the cladding of the optical fiber plate 103 several times to absorb the radiation in the optical fiber plate 103. 1
By tilting 03, the radiation is allowed to pass through the core and the cladding of the optical fiber plate 103 several times, and the radiation is absorbed in the optical fiber plate 103. In this way, in Conventional Technique 2 and Conventional Technique 3, radiation is prevented from entering the solid-state image sensor 102.

In the optical fiber plate 103 shown in FIG. 4, the direction of the solid line indicates the light guiding direction. Hereinafter, also in the other drawings, the direction of the solid line described in the optical fiber plate is the same as in FIG.

Further, as in the X-ray image detector (hereinafter referred to as "prior art 4") shown in FIG. 5, the optical fiber plate 203 is tilted with respect to the scintillator 104, and the optical fiber plate 203 is guided in the light guide direction. In some cases, X-rays are prevented from entering the solid-state imaging device 102 by making the length longer (Japanese Patent Laid-Open No. 2-276996,
JP-A-4-80507). Further, as in the X-ray image detector shown in FIG. 6 (hereinafter referred to as “conventional technology 5”), the scintillator 104 is provided at one end, and the long length of the optical fiber plate 303 is bent to bend the X-ray image detector 303. There is also one in which a line is prevented from entering the solid-state image sensor 102 (JP-A-4-80507).

[0007]

However, in the radiation image detectors of the prior art 2 and the prior art 3, the solid-state image sensor 102 may receive radiation that cannot be absorbed in the optical fiber plate 103. In order to completely absorb the radiation in the optical fiber plate 103 in order to prevent this, the thickness of the optical fiber plate 103 must be increased. However, as the optical fiber plate 103 becomes thicker, the radiation image detector itself is also increased. The size becomes large, which causes various inconveniences.

Further, although the prior arts 4 and 5 can prevent the X-rays from entering the solid-state image pickup device 102, they have the following drawbacks because the length of the optical fiber plate 203 is long. Was there. That is, the disadvantage is that, firstly, there is a time lag between the incident of X-rays on the scintillator 104 and the arrival of the solid-state image sensor 102.
Secondly, the dead space is increased and the X-ray image detector itself is increased in size.

Therefore, an object of the present invention is to provide a radiation image detector that solves the above problems.

[0010]

In order to solve the above-mentioned problems, a radiation detector according to the present invention has two light output end faces and two light input end faces which intersect the waveguide direction of light and are substantially orthogonal to each other. It is characterized by comprising a pair of quadrangular prism-shaped optical fiber plates and a solid-state image sensor provided so that a light incident surface faces a light output end surface.

In order to solve the above-mentioned problems, the radiation detector according to the present invention is a quadrangular prism having two sets of light output end faces and light input end faces that intersect each other with the waveguide direction of light and are substantially orthogonal to each other. A columnar optical fiber plate, a scintillator that is provided on the light input end face side and emits light in response to incident radiation, and a solid-state imaging device that is provided so that the light incident face faces the light output end face. Characterize.

[0012]

According to the above construction, the radiation image detector according to the present invention has a solid state on the light output end face of an optical fiber plate having a light output end face and a light input end face which intersect with the light guiding direction and are substantially orthogonal to each other. Since the image pickup device is provided, visible light other than the radiation incident from the light input end face side propagates in the light guiding direction, exits from the light output end face, and enters the light incident face of the solid-state image pickup device.

Further, since the light input end face which receives radiation and the light input face of the solid-state image pickup element are orthogonal to each other, the length of the optical fiber plate in the light incident direction can be shortened and the light is not converted into visible light. Even when radiation passes through the optical fiber, it does not directly enter the light input surface of the solid-state image sensor.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The same elements are designated by the same reference numerals. In addition, the dimensional ratio of each portion in the drawings does not necessarily match the actual dimensional ratio, and the same applies to the area.

A radiation image detector 1 according to an embodiment of the present invention will be described with reference to FIG. As shown in the figure, the radiation image detector 1 has two sets of a light output end face and a light input end face 31 which intersect the light guide direction at an angle of 45 ° and are substantially orthogonal to each other, and have a substantially cubic shape. The optical fiber plate 3 thus formed and the CCD 2 which is a solid-state image sensor having a light incident surface on the light output end surface are provided. Therefore, CC
The light incident surface of D2 and the surface on which light is incident on the scintillator 4 are substantially orthogonal to each other. A plurality of terminals 21 are provided on both sides of the CCD 2.

A material (for example, cesium iodide) that causes scintillation is applied to the light input end surface of the optical fiber plate 3. Therefore, the coating film (not shown) on the light emitting end surface of the optical fiber plate 3 functions as a scintillator, and when the radioactivity enters the optical fiber plate 3, the coating film emits light accordingly.

That is, the X-ray incident on the light input end face 31 is
It is converted into visible light or the like by the coating film on the light incident end face 31, is guided in each core of the plurality of optical fibers forming the optical fiber plate 3, and is propagated in the waveguide direction of the optical fiber.

In this embodiment, the material having the scintillation function is directly applied to the light input end face 31, but the core of the optical fiber itself may have the scintillation. Further, the scintillator may be provided above the light input end face 31 with a predetermined space interposed, or the scintillator may be provided with a member such as glass that transmits visible light interposed.

Further, as shown in FIG. 2, the light input end face 3
1 may be directly provided with the scintillator 4.
The scintillator 4 is made of a crystal such as cesium iodide (C ₂ I) or sodium iodide (NaI), and converts radiation into visible light (scintillation emission). In addition,
The scintillator 4 may be a single crystal plate, but if it is divided into a plurality of pixel units, crosstalk can be suppressed and a good radiation image can be obtained.

Next, the optical fiber plate used in this embodiment will be described.

The optical fiber plate 3 is formed by a process in which a bundle of a plurality of optical fibers is stretched and cut while applying heat or the like, and then bundled again and integrated and then stretched.
It is formed by repeating a plurality of times and then cutting it into a desired shape. In the optical fiber plate 3, the axial direction of the core is the light guiding direction, the optical input end face 31 of the optical fiber plate 3 has the optical input end face of the core, and the optical output end face has the optical output end face of the core. Therefore, in the optical fiber plate 3 used in this embodiment, the light incident from the light input end face 31 is emitted from the light output end.

Incidentally, the light output end face may be subjected to necessary processing such as unevenness according to the shape of the light incident face of the CCD 2 to be connected, and the light input end face 31 is also formed with the scintillator 4 formed. It goes without saying that the necessary processing may be performed according to the above. In addition, in the radiation image detector 1 according to the present embodiment, a convex portion is formed on the light output end face in accordance with the incident face of the CCD 2.

The shape of the optical fiber plate 4 is not limited to a cube, but may be, for example, a rectangular parallelepiped.

Next, the operation and effect of the radiation image detector according to this embodiment will be described.

In the radiation image detector 1 according to the present embodiment, an optical fiber plate 3 having a light output end face and a light input end face 31 which intersect the light guiding direction and are substantially orthogonal to each other.
Since the CCD 2 is provided on the light output end face and the light input end face 31 is coated with a substance having a scintillation function, the light generated when the radiation enters the light input end face 31 propagates in the light guiding direction. CC emitted from the light output end face
It is incident on the light incident surface of D2. That is, the light generated on the light input end face 31 propagates in the light guiding direction and propagates in the light input end face 3
The light is incident on the light incident surface of the CCD 2 substantially orthogonal to 1.

Further, since the light incident surface of the CCD 2 and the light input end surface 31 are substantially orthogonal to each other, the radiation incident substantially perpendicular to the light input end surface 31 is substantially parallel to the light incident surface of the CCD 2. Since it goes straight on, the radiation does not enter the light incident surface of the CCD 2. Further, the radiation is not guided by the optical fiber plate which optically couples the light incident surface of the CCD 2 and the light input end surface 31.

Therefore, the radiation is emitted from the optical fiber plate 4
Even if the light is transmitted without being absorbed by, the light does not directly enter the light incident surface of the CCD 2. Therefore, in this radiation image detector,
Since the radiation does not directly enter the CCD 2, it is possible to prevent the CCD 2 from being damaged by the radiation, and also possible to reduce the noise due to the radiation.

The radiation to be detected is mainly X-rays, but the radiation is not limited to this, and any radiation can be generated when it enters the scintillator and is not guided by the optical fiber plate. This radiation image detector can be used for such radiation.

Next, the radiation image detector 1 according to the above embodiment
A radiation image detecting module using is explained.

As shown in FIG. 3, this radiation image detecting module is formed by using four radiation detectors 1 shown in the above embodiment and arranging light incident end faces two-dimensionally on the same plane. Therefore, the light emitting end faces are located on the four side faces of the module, one CCD on each side face.
2 is attached. Therefore, a space for mounting the CCD 2 is provided, and the dead space (area where radiation cannot be detected) on the light incident surface is reduced.

In this embodiment, four radiation image detectors 1 are used, but the number of radiation image detectors 1 is not limited to this, and the number may be increased if necessary. , May be reduced. By doing so, it becomes possible to perform measurement in a very wide range.

As described above, according to the radiation detector 1 of the present embodiment, the light of the optical fiber plate 3 having the light output end face and the light input end face 31 which intersect the light guiding direction and are substantially orthogonal to each other. Since the solid-state image sensor is provided on the output end face, it can be formed as a compact device as a whole.

Therefore, it is possible to obtain a radiation image detector which has a small dead space, is compact, and has no deviation from the time when the radiation enters the scintillator to the time when it reaches the CCD.

Further, since the light input end face which receives radiation or light and the light input face of the CCD are orthogonal to each other, the light input face of the solid-state image pickup device is not converted into visible light and radiation is transmitted through the optical fiber. There is no direct incidence on. For this reason,
It is possible to prevent damage to the CCD due to radiation and also reduce noise due to radiation.
The N ratio is improved.

[0035]

As described in detail above, according to the radiation image detector of the present invention, the length of the optical fiber plate in the light incident direction can be shortened, so that a compact radiation image detector can be obtained. You can Further, even if the radiation is transmitted through the optical fiber without being converted into visible light, it is possible to completely prevent the radiation from entering the light input surface of the solid-state image sensor, so that the solid-state image sensor is damaged.
And noise can be reduced.

[Brief description of drawings]

FIG. 1 is a perspective view showing a radiation image detector according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a radiation image detector according to another embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a radiation image detecting module according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a radiation image detector according to a conventional technique.

FIG. 5 is an explanatory diagram showing a radiation image detector according to a conventional technique.

FIG. 6 is an explanatory diagram showing a radiation image detector according to a conventional technique.

[Explanation of symbols]

1 ... Radiation image detector, 2 ... CCD, 3 ... Optical fiber plate, 4 ... Scintillator

Claims (2)

[Claims] 1. A quadrangular prism-shaped optical fiber plate having two sets of a light output end face and two light input end faces, each of which intersects a light guiding direction and is substantially orthogonal to each other, and a light incident face facing the light output end face. And a solid-state imaging device provided in the radiation image detector. 2. A quadrangular prism-shaped optical fiber plate having two sets of light output end faces and two light input end faces, each of which intersects with a light guiding direction and is substantially orthogonal to each other, and incident radiation provided on the light input end face side. A radiation image detector, comprising: a scintillator that emits light in accordance with the above; and a solid-state image sensor provided so that a light incident surface faces the light output end surface.