JPH1039036A - Two-dimensional radiation detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-dimensional radiation detector capable of suppressing lowering of sensitivity and occurrence of a crosstalk and of taking out outputs of all of elements in a short time without raising a scanning frequency. SOLUTION: A single-dimensional radiation detector 10 is so constituted that scintillator sheet 2 is laminated to each of plural photodetectors 1a-1a and each of photodetectors of a single-dimensional photodetector 1 having a transferring function of an output of each of the photodetectors 1a-1a. The multiple of detectors 10 are laminated in the same direction as the above laminating direction and a two-dimensional detection area is formed in the lamination direction and in the arrangement direction of the photodetectors 1a-1a, thereby obtaining two-dimensional radiation image information based on a scanning cycle of the single-dimensional photodetector device 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-dimensional radiation detector which can be used for an X-ray foreign substance inspection apparatus used for nondestructive inspection and the like and an X-ray CT or a general photographing apparatus.

[0002]

2. Description of the Related Art A two-dimensional digital radiation detector has been required with the progress of radiation imaging technology. At present, X-ray fluorescence intensifiers (II; image intensifiers), fluorescent screens, and X-ray vidicons are generally used. However, many conversion steps are required until an image is converted into digital information. Therefore, there is a problem that the resolution is deteriorated due to the scattered light and the S / N is also poor. In order to solve such a problem and respond to the above demand,
Research has been conducted on a two-dimensional radiation detector in which a scintillator is bonded to an amorphous Si two-dimensional image sensor.

[0003]

In an amorphous Si two-dimensional image sensor, it is necessary to read out the output of each sensor element through a scanning network in the x and y directions. As the wiring width increases, the sensitivity decreases due to an increase in the wiring capacitance, which is a problem in terms of crosstalk between adjacent elements and the production yield. Furthermore, when the number of elements increases, noise increases due to the increase in the scanning frequency, and the time required to capture the output of all elements increases. Therefore, in OA equipment, etc., up to one-dimensional image sensors can be used for general use of two-dimensional image sensors. The fact is that it has not arrived.

[0004] From the above, as for a radiation detector using an amorphous Si image sensor, although a one-dimensional radiation detector has been put to practical use, a two-dimensional radiation detector can be realized only in a small size at present. It has not been.

An object of the present invention is to solve the above-mentioned problems of an amorphous two-dimensional image sensor and a conventional two-dimensional radiation detector using the same at once. Even if the number and size of the elements are increased, there are few problems of sensitivity reduction and crosstalk, the production yield is good, and even if the number of elements is increased, the capture time of all the element outputs without increasing the scanning frequency It is an object of the present invention to provide a two-dimensional radiation detector capable of shortening the length of the conventional radiation detector.

[0006]

A configuration for achieving the above object will be described with reference to FIGS. 1 and 2 showing an embodiment. In the two-dimensional radiation detector of the present invention, a one-dimensional radiation detector is provided. A plurality of light receiving elements 1a... 1a and a one-dimensional photodetector 1 having an output function of each element output are provided with scintillator sheets 2 that emit light in accordance with the amount of incident radiation. Are stacked in the same direction as the stacking direction of the light receiving elements 1a... 1a and the scintillator sheet 2, and the stacking direction and the one-dimensional radiation detector 1 A two-dimensional detection area is formed in the arrangement direction of the light receiving elements 1a... 1a.

According to the present invention, a one-dimensional radiation detector in which a scintillator sheet is adhered so as to cover each light receiving element of the one-dimensional photodetector has already been put into practical use and has not caused the above-mentioned problems. Utilizing that, in view of the structure of the one-dimensional radiation detector, by laminating a large number of them in the same direction as the lamination direction of the light receiving element and the scintillator sheet, to constitute a two-dimensional radiation detector as a whole, It is intended to solve the above problems.

That is, in the present invention, each one-dimensional radiation detector 10 is laminated in the same direction as the lamination direction of the respective one-dimensional photodetector 1 and scintillator sheet 2, and the lamination direction and the one-dimensional photodetector 1 are stacked. A two-dimensional detection area is formed by the arrangement direction of the light receiving elements 1a. Therefore, radiation enters the scintillator sheet 2 of each one-dimensional radiation detector 10 from the side surface portion thereof, and the light generated thereby enters the one-dimensional photodetector 1 via each transfer function (scanning circuit). It is output to the outside as one-dimensional radiation information. Then, two-dimensional radiation information is obtained from the set of each one-dimensional radiation information.

In such a configuration, each one-dimensional radiation detector 10 has its own output transfer function (scan circuit),
Since the one-dimensional information of the incident radiation is independently output to the outside, without increasing the scanning frequency so much,
Two-dimensional radiation information can be obtained in a relatively short time. at the same time,
The light receiving elements 1a... 1a of the one-dimensional photodetectors 1
Instead of two-dimensionally arranging the light-receiving surfaces on the same plane as in the case of a three-dimensional detector, the light-receiving surfaces are substantially arranged one-dimensionally, so that the distance to an amplifier circuit and the like can be reduced. In addition, the problems of sensitivity reduction and crosstalk between adjacent elements can be greatly reduced. Further, according to the configuration of the present invention, the manufacturing yield can be improved as compared with the conventional two-dimensional detector, because the manufacturing can be performed by simply stacking a large number of one-dimensional radiation detectors 10.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of an embodiment of the present invention. FIG. 1 (A) is a front view viewed from a radiation incident direction, and FIG. 1 (B) is a right side view thereof. FIGS. 2A and 2B are explanatory views of the one-dimensional radiation detector 10 used in the present embodiment. FIG. 2A is a diagram viewed from the front side of the scintillator sheet 2, and FIG. Is shown.

As shown in FIG. 1, in this embodiment, a large number of one-dimensional radiation detectors 10 are stacked on each other, and the whole constitutes a two-dimensional radiation detector. Each one-dimensional radiation detector 10 is a known one, and as shown in FIG. 2, the scintillator sheet 2 is laminated on the light receiving surface of each light receiving element 1a... 1a of the one-dimensional light detector 1 and adhered to each other. Each of the one-dimensional photodetectors 1 has a large number of light receiving elements 1a,.
And a plurality of driving IC chips 1b... 1b including a scanning circuit for transferring the output of each element are mounted on a substrate 1c, and each light receiving element 1a... 1a and each driving IC chip 1b.
1b is connected by wire bonding to a one-dimensional Almoface Si image sensor. Note that FIG.
Numeral 3 is a connector for supplying a power supply and a drive pulse and for taking out the output of each element.

Here, in the above-described one-dimensional radiation detector 10, the material of the substrate 1c is often made of ceramics, but in this embodiment, the material of the substrate 1c is lead glass. .

Each drive IC chip 1b has a buffer amplifier 101 corresponding to each element 1a... 1a as shown in FIG.
And the shift register 102a and the switch element 102
b including a scanning circuit 102 for data transfer, a switch element 103 for resetting, etc.
It has a function of sequentially taking out the accumulated charges generated by the incidence of light on 1a as external voltage signals from the connector 3 to the outside.

The one-dimensional radiation detector 10 as described above has
In the normal use method, the surface of the scintillator sheet 2 is used as a radiation incident surface. However, in the embodiment of the present invention, many of the one-dimensional radiation detectors 10 are connected to the respective scintillator sheets 2 and the light receiving surfaces. Element 1a ... 1
a are mutually laminated in the same direction as the lamination direction. Therefore, in the two-dimensional radiation detector of this embodiment, the stacking direction of each one-dimensional radiation detector 10,...
.. A two-dimensional detection area is formed with the arrangement direction of 1a.

The thickness of the light receiving elements 1a is 1 to 2
μm, and the thickness of the scintillator sheet 2 is 0.1 to
The thickness of the driving IC chip 1b is about 0.4 mm. Accordingly, each of the substrates 1c made of lead glass has a drive IC chip 1b
A pit P for accommodating a part of these is formed in order to avoid interference by the thickness of 1b.

The thickness of the substrate 1c made of lead glass can be arbitrarily set as long as it is not less than about 0.3 mm, whereby the pitch between the one-dimensional radiation detectors 10,... Pixel pitch in the stacking direction is 0.6
About 1.0 mm. The pixel pitch in the arrangement direction of the light receiving elements 1a.
Any value can be set as long as it is at least 05 mm.

According to the above embodiment of the present invention, FIG.
Radiation R incident from the direction indicated by the arrow in (B) is incident on each of the scintillator sheets 2. The light is detected by the light receiving elements 1a,... 1a in close contact with the respective scintillator sheets 2, and the driving IC chips 1b,.
The data is read out externally as one-dimensional radiation image data independently via 1b. Then, by arranging such one-dimensional image data for each one-dimensional radiation detector 10 spatially in relation to the stacking order of each one-dimensional radiation detector 10 by an external image processing circuit, 2D A two-dimensional radiation image is obtained.

Here, according to the radiation incident direction as described above, the radiation enters the light receiving elements 1a... 1a from the side surfaces, but the amorphous Si constituting the light receiving elements 1a. As described above, as thin as 1-2 μm,
Therefore, there is little damage due to little radiation absorption. Since the driving IC chips 1b are provided behind the scintillator sheet 2, they are not damaged by radiation.

Further, since each substrate 1c is made of lead glass, these substrates 1c... 1c function as a grit, and an effect of suppressing imaging of scattered X-rays by a subject can be obtained. That is, the radiation scattered when transmitted through the subject is reflected on the substrate 1 c.
The incidence of the light on the scintillator sheet 2 is prevented by the presence of c.

It should be particularly noted in the above embodiment that two-dimensional radiation image data can be obtained substantially at the scanning period of each one-dimensional radiation detector 10, and without increasing the scanning frequency. The point is that image information consisting of all two-dimensional pixels can be obtained under a short cycle. Also, it should be noted that although the light receiving elements 1a... 1a are arranged two-dimensionally as a whole, in practice, the driving ICs 1b are arranged independently for each row and adjacent to the row. ..1
Since it is driven by b, the wiring distance between each element and the amplifier section is shorter than that of a normal two-dimensional detector, and the reduction in sensitivity and the occurrence of crosstalk can be greatly suppressed.

In the above embodiment, the light receiving elements 1a,... 1a are made of amorphous Si. However, the present invention is not limited to this, and any semiconductor optical sensor can be used. is there.

[0022]

As described above, according to the present invention, a large number of one-dimensional radiation detectors comprising a plurality of light-receiving elements, a one-dimensional photodetector having a function of transferring the output thereof, and a scintillator sheet are stacked. Are stacked to form a two-dimensional radiation detector having a two-dimensional detection area in the stacking direction and the arrangement direction of the light receiving elements, so that a two-dimensional radiation detector is formed based on the scanning cycle of the one-dimensional radiation detector. Radiographic image information,
Two-dimensional all-pixel information can be obtained without increasing the scanning frequency so much. Therefore, it is possible to suppress the generation of noise due to the scanning signal.

Also, since the present invention is originally constructed by stacking the one-dimensional detectors in the above-described direction,
2 using conventional two-dimensional photodetector and scintillator sheet
Compared to a two-dimensional radiation detector, the wiring distance between each light-receiving element and the drive circuit can be shortened, and the problems of reduced sensitivity and the occurrence of crosstalk can be significantly reduced. It can be improved.

From the above, according to the present invention, a practical two-dimensional radiation detector having a good S / N can be obtained.

[Brief description of the drawings]

FIGS. 1A and 1B are explanatory views of an embodiment of the present invention, in which FIG. 1A is a front view viewed from a radiation incident direction, and FIG.

FIG. 2 is an explanatory view of a one-dimensional radiation detector 10 used in an embodiment of the present invention, in which (A) shows a scintillator sheet 2 thereof;
(B) is a right side view of the front view shown from the surface of FIG.

FIG. 3 is a driving IC chip 1 used in the embodiment of the present invention.
FIG. 2B is an explanatory diagram of an example of a circuit diagram of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 One-dimensional photodetector 1a ... 1a Light receiving element 1b Drive IC chip 1c Substrate 2 Scintillator sheet 10 One-dimensional radiation detector P pit

Claims (1)

[Claims] 1. A one-dimensional photodetector having a plurality of one-dimensionally arranged light receiving elements and a function of transferring the output of each element,
Many one-dimensional radiation detectors in which scintillator sheets that emit light in accordance with the amount of incident radiation are stacked so as to cover the light-receiving elements are stacked in the same direction as the stacking direction. A two-dimensional radiation detector formed with a two-dimensional detection area in the arrangement direction of the light receiving elements.