JPH0283489A - Multielement radiation detector - Google Patents

Abstract

PURPOSE:To make signal output constant by making the light reflectivity of the surface of an indivisual scintillator constant by adhering a light reflecting film having the same characteristics to the surfaces of a plurality of scintillators constituting a detector. CONSTITUTION:Scintillators 3 are bonded and fixed to the upper surface of the photodiode array 5 consisting of a plurality of elements fixed to a substrate 6 composed of ceramic or glass-epoxy. A light reflecting film 1 begins to cover the side surface of the detection element at one end and the coating thereof is finished on the side surface of the detection element at the other end. The light reflecting film 1 is also inserted in the gaps between the adjacent detection elements and partition wall plates 2 are subsequently inserted in said gaps to be fixed. As mentioned above, since this detector is assembled by using one continuous film, assembling is extremely easy and characteristic irregularity at every element can be reduced by half.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a multi-element radiation detector, which is suitable for measuring one-dimensional intensity distribution of radiation, and is suitable for inspecting objects using X-rays. The present invention relates to a multi-element radiation detector suitable as a detector for an X-ray CT device or an X-ray CT device.

[Conventional technology]

The main characteristics required for multi-element detectors used in X-ray CT devices and inspection devices that take X-ray transmission images are high detection sensitivity and the sensitivity of each element. In order to obtain a high-quality image, it is necessary that the signal is constant and that there is little leakage of signals to adjacent elements. In a multi-element detector consisting of a scintillator that emits radiation due to radiation such as X or gamma rays and an element that photoelectrically converts the scintillator light, in order to achieve the above requirements, the surface of the scintillator must contain all of the internally generated light. In order to create a light reflecting surface so that it enters the photoelectric conversion element and eliminate signal leakage (crosstalk) to neighboring elements,
A structure is used in which a plate opaque to light and X-rays is inserted as a partition plate between adjacent scintillators. The electrical output changes because the amount of light loss changes depending on the size of the light reflecting film installed on the surface of the scintillator. The reflective film can be created by forming a highly reflective metal film on the entire surface by plating or vapor deposition, by coating the entire surface with white paint, or by coating both sides of the partition plate 7 with light reflecting material as shown in Figure 4. A method is used in which a surface reflects light in an adjacent direction and another reflective film 1 is provided on the X-ray incident surface. In these conventional techniques, the sensitivity variation between detection elements is reduced to 1
It is difficult to reduce the amount to 0% or less. Further disadvantages of the conventional technology are that it is difficult to control or select the reflectance value to a constant value at the component stage or material state, and furthermore, it is impossible to repair or improve in the case of defects, and It is economically disadvantageous because the yield of the above-mentioned products becomes poor. Note that this type of device is disclosed in US Pat. No. 4,720,426.

[Problem to be solved by the invention]

In the prior art, as a method of forming a reflective film on the surface of a plurality of scintillators, a reflective film is attached to each individual scintillator. In this method, it is difficult to keep the reflectance of each scintillator constant, and therefore it is impossible to keep the individual signal output constant.

An object of the present invention is to make the light reflectance of each scintillator surface constant, thereby making the signal output constant.

[Means to solve the problem]

The above object is achieved by bringing a thin film-like film with high light reflectance into close contact with the surface of a scintillator, and by using one film in a continuous state over a plurality of elements. The light-reflecting film used here is one that has little change in reflectance depending on location, so that the surface reflectance of the plurality of scintillators can be kept constant, and variations in the output characteristics of individual scintillators can be reduced.

[Effect]

By attaching a light reflection film with the same characteristics to the X-ray incident surface of the scintillator and the side surface of the scintillator, that is, the surface facing the adjacent scintillator, the light reflection characteristics become the same, and the same light reflection is applied to multiple scintillators. Since the film is used continuously to cover the surface of the scintillator, the light reflection characteristics are the same, which is effective in reducing variations in characteristics of a multi-element radiation detector.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view of a detector array according to an embodiment of the present invention. FIG. 2 is an external view of a detector array according to an embodiment of the present invention. A scintillator 3 having multiple elements is bonded and fixed to the upper surface of a first diode array 5 having multiple elements fixed on a substrate 6 made of ceramic or glass epoxy. There is an X between the elements of scintillator 3.
In order to prevent radiation crosstalk, a partition plate 2 made of metal that is impermeable to X-rays is inserted. scintillator x-ray 4
The entrance surface and the side facing the neighboring elements are coated with a light-reflecting film 1, which is continuous over all the elements of the detector array. Materials for the scintillator 3 that emit light due to radiation include CdWOa and CsI(
Tffi), BGO.

There are rare earth oxide scintillators, rare earth sulfide scintillators, etc., and the energy of the radiation is determined by the type of radiation and the type of equipment. A ceramic scintillator using CdzOzS.Pr-Ce-F is used as a detector for a medical XaCT device. The dimensions are width 1.0nm, length 30nm, thickness 1mm, and the spacing between each detection element is 0.1 nrn. The light reflecting film 1 is a Mylar film with a thickness of 10 to 30 μm, with an aluminum vapor-deposited film formed on one side, and has a light reflectance of 80% or more, with a variation in reflectance of 1% or less depending on location. The material and thickness of the partition plate 2 that separates the detection elements are determined depending on the energy of the radiation, but medical X-ray C
In the T device, molybdenum or tungsten plates with a thickness of 0.05 to 0.1 ann are used.

Although the surface condition needs to be flat, it does not need to have high light reflectance.

The light reflective film 1 begins to cover the side surface of the edge detection element,
The adjacent detection elements are successively coated one after another, and the coating ends at the side surface of the detection element at the other end. It is also inserted into the gap between adjacent detection elements, and after inserting the light reflecting film 1, the partition plate 2 is inserted and fixed. Although not shown, the partition plate 2 and the light reflective film 1 are fixed at the longitudinal ends of the partition plate 2, and the substrate 6
This is done by adhering it with adhesive. Gap between detection elements is 0
．． In the case of 1mm, 0.05mm partition plate and 0.01mm
A detector with uniform characteristics was obtained by assembling it using a 2 m thick light reflective film. Detectors used in X-ray CT devices and X-ray baggage inspection devices have 500 or more detection elements. In this case, the detector array is manufactured in one piece, so as shown in FIG. 3, a plurality of detector arrays each having a plurality of elements are arranged in a plurality of tubes to form a detector having the required number of detection elements.

According to the present invention, as a material covering the scintillator,
Since all the detection elements are covered with a film that has high light reflectance and little variation depending on location, there are no differences in the characteristics of each detection element, and a detector with uniform characteristics can be obtained. It is easy to measure the characteristics of a light reflective film, and its performance can be inspected and managed, which is highly effective in preventing the occurrence of defects.

〔Effect of the invention〕

According to the present invention, since the surfaces of the plurality of scintillators constituting the detector are coated with a thin film having a predetermined light reflectance, variations in output characteristics can be reduced. For multi-element detectors, assembly is extremely easy, as it uses two consecutive films. - Compared to the conventional method of attaching a light reflection treatment to the scintillator surface for each element, the variation in characteristics between elements has been halved.

Since it is easy to measure and inspect the reflectance of a film-like light-reflecting film, sufficient control can be carried out before assembly, which is effective in improving yield.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a detector array according to an embodiment of the present invention, FIG. 2 is an external view of a detector array according to an embodiment of the present invention, and FIG.
The figure is a sectional view of a state in which a plurality of detector arrays according to an embodiment of the present invention are arranged, and FIG. 4 is a sectional view of a conventional detector array. DESCRIPTION OF SYMBOLS 1... Light reflective film, 2... Partition plate, 3... Scintillator, 4... Incident X-ray, 5... Photodiode array, 6... Substrate, 7... Conventional example Partition plate with surface light reflective layer.帛 l ri? No. 2 B No. 32

Claims (1)

[Claims] 1. In a multi-element radiation detector composed of a plurality of scintillators and a plurality of photodiode arrays, a light reflecting film is provided on one side of the radiation incident surface of the scintillator and the side surface facing the adjacent scintillator. The scintillator is covered with a continuous light-reflecting film formed with a scintillator, and a plurality of partition plates made of a material impermeable to X-rays are inserted between each scintillator. Element radiation detector. 2. The multi-element radiation detector according to claim 1, wherein the light reflecting film is made of polyester with aluminum vapor-deposited on one side.