JPS6224174A - Radiation detector - Google Patents

Abstract

PURPOSE:To uniformize electric characteristic per each detecting element, by constructing a composite with tightly contacted scintillator element and separating reflecting board, and joining at least one side end surface excepting radiation incident surface, projecting surface and surface facing to the neighboring element of the scintillator element of this composite with bonding agent. CONSTITUTION:The detector is composed of a plurolity of scintillator elements 2 and a plurality of separating reflecting board 6, the elements 2 and boards 6 being arranged alternately, and the composite body 30 made of the tightly joined elements 2 and boards 6 is fixed on an arroy of photoelectric convertor elements 5 and a detecting signal of each element 2 is taken out from a connector 14. Further, for material of the reflecting board for separating the elements 2, a metallic is used for reducing a crosstalk caused by infiltration of scattering X-rays of the neighboring element 2. And, by ioming at least one surface side excepting incident surface, projecting surface and surface facing to the neighboring element 2 of the element 2 of the composite body 30 with bonding agent, uniformalization in approximation of the reflecting surface of the reflecting board 6 can be achieved and thus uniformization of electric characteristic per each detecting element of the detector becomes available.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an X-ray detector used in an X, Wt tomography apparatus W (hereinafter referred to as an X@CT apparatus) using a computer, and in particular, The present invention relates to a technique that is effective when applied to a multi-element X-ray detector consisting of a scintillator element and a plurality of photoelectric conversion elements, in which the electrical characteristics of each detection element are made constant.

[Background technology]

An overview of one imaging method of the XIIACT apparatus according to the present invention will be explained.

An X-ray source that emits fan-shaped beam X-rays and a multi-element X-ray detector (hereinafter simply referred to as the detector) are set to face each other at a predetermined distance, and a fan-shaped beam is generated between the X-ray source and the detector. Place the subject in the X-ray, rotate the X-ray source and detector around the subject, irradiate the subject with X-rays from multiple directions, obtain a total of 81 X-ray intensity distributions, and calculate the measured signal using an electronic computer. This method obtains a tomographic image of the subject through processing.

Also.

Even if the X-ray source and detector are fixed and the subject is rotated, the same tomographic image can be taken, and it is also used in non-medical imaging devices. In this type of apparatus, there is a problem in that if there are variations in the sensitivity of the detection elements of the detector, identical circular artifacts will occur on the reproduced image. In other words, with respect to changes in the energy and dose of X-rays incident on the detector, the allowable values for variations in the output of each detection element of the detector are comprehensively determined based on various correction processes and image discrimination ability. It will be done. -For example, X@
When the tube voltage is changed from 120KV to 80KV, the allowable variation in output change between each detection element is 0.1%.
The following is required: In the detector comprising a plurality of scintillator elements and a plurality of optical conversion elements according to the present invention, the structural cause of variations in sensitivity among the detection elements of the detector is as shown in FIG. Scintillator cord 2
The light emitted by the X-ray 1 that has entered the scintillator element 2 passes through the scintillator element 2, and the light 4 that is directly incident on the photoelectric conversion element 5 and the adjacent detection element.

There is light 3 that is reflected by the separation reflection plate 6 that separates the detection elements and input to the photoelectric conversion element 5, and both become photoelectric outputs, but the light reflected by the separation reflection plate 6 is attenuated if the reflectance is low. As a result, the photoelectric output becomes smaller.

Also, for the depth D in the incident direction of xm, the detection element width W
In the case of a structure with a small
Variations in the reflectance of the surface of the separation reflecting plate 6 cause variations in output.

Furthermore, variations in the gap between the scintillator element 2 and the separation reflection plate 6 also cause output variations. For this reason, in order to construct a detector with large output and small variations in characteristics from element to element, the reflectance of the reflector for one section should be constant.
And there is a demand for it to be larger.

Here, as shown in FIG. 6, conventionally used detectors include those in which a scintillator element 2 and a separation reflection plate 6 are bonded and stacked with adhesive to form a multi-element type detector. be. That is, the separation reflection plate 6 and adhesive are inserted into the joint 7 where one scintillator element 2 and the adjacent scintillator element 2 are in contact with each other, and the adhesive is inserted to form a block of multiple detection elements, and the scintillator element 2 is connected to the joint surface 8. It is bonded and fixed to the photoelectric conversion element 5.

Further, as shown in FIG. 7, a separation reflection plate 6 is inserted into the gap 9 between one scintillator element 2 and the adjacent scintillator element 2, and the detection element provided by each scintillator element 2 and separation reflection plate 6 is Some are separately bonded and fixed at the bonding surface 8 to the photoelectric conversion element 5.

In the detector having the structure shown in FIG. 6, the amount of adhesive is not constant and bubbles remain, so that the reflection state of the separating reflector 6 changes depending on the location and the detection element. In addition, visual inspection of the adhesion state is not possible with this structure;
There is a problem in that when measurement data varies, it is not possible to determine the cause.

In addition, in the detector having the structure shown in FIG.
The distance between the scintillator element 2 and the side surface of the scintillator element 2 is not constant, which causes a problem in that output characteristics vary.

[Purpose of the invention]

An object of the present invention is to provide a technique that can reduce variations in sensitivity among detection elements in a detector including a plurality of scintillator elements and a plurality of photoelectric conversion elements.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of one typical invention disclosed in this application is as follows.

That is, in a detector composed of a plurality of scintillator elements and a plurality of photoelectric conversion elements, a separation reflection plate is placed between each scintillator element, and the scintillator element and separation reflection plate are brought into close contact to form a composite. , characterized in that at least one side of the scintillator element of the composite body other than the radiation incident surface, the light emitting surface, and the surface facing an adjacent element is connected with an adhesive, and the sensitivity of each detection element of the detector is This reduces the variation in .

An embodiment of the present invention will be described below with reference to the drawings.

Note that throughout the description of the embodiments, parts having the same functions are given the same reference numerals, and repeated explanations thereof will be omitted.

[Example ■]

Figures 1 and 2 are examples of the present invention! FIG. 1 is a perspective view showing a schematic configuration of the detector, and FIG. 2 is a side view of FIG. 1.

As shown in FIGS. 1 and 2, the detector of Example I includes a plurality of scintillator elements 2 and a plurality of separation reflection plates 6.
A composite body 30 in which scintillator elements 2 and separation reflection plates 6 are arranged alternately and the scintillator elements 2 and separation reflection plates 6 are brought into close contact is fixed on an array of photoelectric conversion elements 5, and each The structure is such that the signal of the detection element is extracted from the connector 14. Although the number of detection elements is not determined, it is convenient to make it a multiple of $1 from the viewpoint of the configuration of the data collection system connected to the output. - As an example, a detector composed of eight elements will be described below.

When the scintillator element 2 that emits light by radiation or X-rays is intended for use in a detector for an XIIACT device, its types are limited, and CdWO4L ZnWO
41Cs I T Q Among other rare earth phosphors, G
d202S-Pr-Ce-F, etc., and these materials have high conversion efficiency from X-rays to light.

The emission spectrum matches the sensitivity distribution of the silicon photodiode used as the photoelectric conversion element 5.

Moreover, it satisfies required performance such as little afterglow, and one of these is used.

An example of the shape and dimensions of the scintillator element 2 is as follows.

The width is 1.2+m, the length is 25mm, and the thickness in the X-ray incident direction is 3I. The material of the separation reflection plate 6 for separating the scintillator elements 2 is selected from the following materials in order to reduce crosstalk caused by leakage of scattered X-rays from adjacent scintillator elements 2.
Use a metal plate. This metal plate is preferably a high-density metal with a high atomic number as much as possible. This example! In,
A molybdenum plate with a thickness of 0.1 ms was used. The surface of the molybdenum plate is aluminum vapor-deposited and subjected to reflection enhancement treatment to make it a reflective surface that reflects the light emitted by the scintillator element 2 and makes it incident on the photoelectric conversion element 5 in the side direction. Processing is performed to reflect 80% or more.

Next, this example! The method of assembling the detector will be explained using FIGS. 1 to 3.

The scintillator elements 2 and the separation reflection plates 6 are arranged alternately and pressed from the direction of the arrow 20 by a compression device 21 such as a compressor, so that the scintillator elements 2 and the separation reflection plates 6 are brought into close contact with each other to form a composite. This state is maintained, and adhesive 11 is applied to both ends (adhesive parts) 10 of the composite to fix the eight scintillator elements 2 and the separation reflection plate 6 to form a composite 3o. The adhesive 11 preferably has a high viscosity; for example, it is preferable to use an ultraviolet curable connecting agent, and the adhesive 11 adheres without penetrating into the gaps between the detection elements.

Note that adhesive 11 is applied to both ends 10 of the composite body of the scintillator elements 2 and the separation reflection plate 6 to fix the eight scintillator elements 2 and the separation reflection plate 6 to form a composite body. However, the composite 30 may be formed by applying adhesive 11 only to one side of the end lO of the composite to fix the eight scintillator elements 2 and the separation reflector 6.

The composite body 30 of the eight scintillator elements 2 and the separation reflection plate 6 is placed on each of the eight photoelectric conversion elements 5 arranged on the wiring board 12, and the arrangement pitch of each photoelectric conversion element 5 is adjusted. The positions of the eight scintillator elements 2 are precisely aligned and fixed. Adhesion in this case also applies to the end 1 of the composite.
0, and the composite 30 and the wiring board 12 are coupled via the photoelectric conversion element 5.

Then, each photoelectric conversion element 5 and the wiring of the wiring board 12 are electrically connected by bonding wires 13, and each terminal (pin) of the connector 14 and each photoelectric conversion element 5 are electrically connected.

Experiments have shown that the variation in electrical characteristics of each detection element of a detector configured in this way is 17% higher than that of a conventional structure.
The result was a reduction of 3.

When the detector of this embodiment (2) is applied to an X-ray CT apparatus, as shown in FIG. 4, a plurality of the detectors are arranged and attached to fit the fan-shaped beam xH.

As can be seen from the above description, according to the second embodiment (2), a separation reflecting plate 6 is arranged between each scintillator element 2 to form a composite, and the radiation incident surface of the scintillator element 2 of this composite is By connecting at least one surface other than the emission surface and the surface facing the adjacent element with adhesive, the reflective surface of the one-minute layer reflector can be made to have an approximately average reflectance, so the detector The electrical characteristics of each detection element can be made constant.

According to the XAIICT apparatus using the detector of Example 1, it is possible to obtain a high quality clear tomographic image with few noise components.

[Example ■]

The detector of this embodiment (2) is as shown in FIG.

A plurality of scintillator elements 2 are arranged radially toward the X-ray generation source, and a separation reflection plate 6A having a triangular cross section is arranged between each scintillator element 2, and the scintillator elements 2 and separation reflection plate 6A are arranged. At least one of the scintillator elements 2 of the composite 30A other than the radiation entrance surface, the emission surface, and the surface facing the adjacent element is pressed in close contact with the other.
The sides are connected with adhesive.

When the detector of this embodiment
It is used by arranging and attaching it to suit the shaped beam X-ray.

By configuring the detector in this way, the electrical characteristics of each detection element of the detector can be made constant.

The present invention has been specifically explained above based on examples.
It goes without saying that the present invention is not limited to the embodiments described above, and can be modified in various ways without departing from the spirit thereof.

〔effect〕

As explained above, according to the present invention, a separation reflection plate is arranged between each scintillator element, the scintillator element and the separation reflection plate are brought into close contact with each other to form a composite, and the scintillator elements of this composite are By connecting at least one side end side other than the radiation entrance surface, the emission surface, and the surface facing the adjacent element with an adhesive, the reflection surface of the separation reflector can be made to have an approximately average reflectance. The electrical characteristics of each detection element of the detector can be made constant.

According to the X-ray CT apparatus using the detector of the present invention, it is possible to obtain high-quality clear tomographic images with few noise components.

[Brief explanation of the drawing]

1 and 2 are diagrams for explaining a detector according to Example I of the present invention. FIG. 1 is a perspective view showing a schematic configuration of the detector according to Example I; is a side view of FIG. 1, FIG. 3 is a diagram for explaining the method of assembling the detector of Example I, and FIG. 4 is a case in which the detector of Example I is applied to an X-ray CT apparatus. An explanatory diagram. FIG. 5 is a cross-sectional view for explaining the schematic configuration of the main parts of the detector of Example (2), and FIGS. 6 to 8 are diagrams for explaining the problems of the conventional detector. In the figure, 1...X-ray, 2...Scintillator element, 3°4...Light, 5...Photoelectric conversion element, 6...Reflector for separation, 8...Photoelectric conversion element 10... End of composite body, 11... Adhesive, 30. 30A... Composite body.

Claims (3)

[Claims] (1) In a multi-element radiation detector composed of a plurality of scintillator elements and a plurality of photoelectric conversion elements, a separation reflection plate is arranged between each of the scintillator elements, and the scintillator element and separation reflection plate are brought into close contact to form a composite a radiation incident surface and a light emitting surface of the scintillator element of the composite;
A radiation detector characterized in that at least one surface other than the surface facing an adjacent element is connected with an adhesive. (2) The radiation detector according to claim 1, wherein a metal plate is used as the separation reflecting plate. (3) The radiation detector according to claim 1, wherein the scintillator elements are arranged radially.