JPS61226677A - Two-dimensional radioactive ray detector - Google Patents

Abstract

PURPOSE:To form a two-dimensional radioactive ray detector with a high sensitivity and a high resolution by leading an optical signal outputted from each scintillator composed of picture elements to the photoelectric element of an integrated circuit input part through an optical guide path composed of optical fiber, for instance and converting it into an electrical signal. CONSTITUTION:A scintillator matrix plate 2 is constituted in such a way that 1,024 pieces of square solid-state scintillators 1 having 0.3mmX0.3mm square bottoms are closely arrayed in a horizontal direction to obtain a set of scintillators, and 1,024 sets of them are piled up in a longitudinal direction. At the reverse side of an image receiving plane, the end part of each scintillator is processed in a projecting shape to form a convex lens, and a light beam emitted from the scintillator 1 is condensed at the light receiving end of an optical fiber 8 having a glass diameter of 0.14mm and a core diameter of 0.1mm. The light beam emitted from each scintillator, which is inputted to the photodiode 5 of the integrated circuit optical signal input part from each optical fiber 8, is converted into an electrical pulse signal.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a two-dimensional radiation detection device.

<Prior art> ′ As an imaging device that uses radiation such as X-rays and T-rays, it has been developed
The most well-known are X-ray cameras and gamma-ray cameras, which take a photographic image of a subject by placing a special emulsion film with photosensitive characteristics on the image-receiving surface. The intensity distribution of radiation is reflected in the degree of blackening of the exposed emulsion film, but measuring the degree of darkening cannot accurately determine the radiation intensity quantitatively. It is impossible to know the information in detail.

On the other hand, there is a method that scans the image receiving surface with a Geigagar counter and converts the radiation intensity into an electrical signal to precisely measure it, but this method is suitable for detailed analysis of information about the local area of the image receiving surface. , it is extremely inconvenient to comprehensively grasp information from the entire subject. Therefore, such a method is more
It is used for line analysis equipment, etc.

Moreover, with any of the above methods, it is impossible to obtain information in response to changes in the radiation intensity from various parts of the object or in the shape of the object itself if there are fairly rapid temporal changes. Therefore, a method has been considered in which the image receiving surface is divided into a large number of pixels and the radiation incident on each pixel surface is converted into an electrical signal to capture an image. This method has been applied to gamma-ray cameras, but not only is the configuration extremely complex, but there are also many problems that need to be solved in order to achieve high-sensitivity, high-resolution imaging, as described below. .

<Problems to be solved by the invention> For example, in the case of a medical X-ray imaging device, the size of the image receiving surface is
It is desired that the image receiving surface is composed of 1000 x 1000 or more pixels (0 cm x 30 cm), and it is necessary to complete imaging within several milliseconds. Furthermore, in order to obtain information with high sensitivity and little loss, it is necessary to detect the intensity of radiation incident on each pixel in units of photons. Therefore, for example, a single scintillator is placed on the image receiving surface to convert a radiation image into an optical image, and this image is received as an electrical signal by an integrated circuit for optical pulses, which has photoelectric elements arranged in a matrix in its input section. It is possible to do (
In this case, each photoelectric element of the integrated circuit input section becomes a pixel).

However, in existing integrated circuits of this type, the number of photoelectric elements is 3.
2 x 32 = 1024, the light receiving area of the input section is 1 (
bm2, it is impossible to cover the image receiving surface of 30 cm x 30 cm at the bottom of the side, and it is not expected that an integrated circuit with such a large light receiving area will be realized in the future. Of course, even if a large number of integrated circuits are used, the light receiving window frames of the arranged integrated circuits divide the image receiving surface vertically and horizontally, making this impractical. The present invention aims to solve the above problems and provide a two-dimensional radiation detection device with high sensitivity and high resolution.

<Means for solving the problem> In order to solve the above problem, in the present invention, a large number of scintillators arranged in a multi-IJ sock shape are arranged on the radiation image receiving surface, and the radiation image is At this stage, the image receiving surface is divided into a large number of pixels, and the optical signal from each scintillator is guided to each photoelectric element of the signal input section of the integrated circuit for receiving optical signals. Therefore, the radiation detection device according to the present invention includes a plurality of scintillators closely arranged on a radiation detection surface, and a plurality of scintillators that guide the output light of each scintillator to a photoelectric conversion element corresponding to each of the plurality of scintillators. The signal input section is composed of a plurality of optical guide paths and a plurality of optical-to-electric conversion elements arranged with respect to the plurality of optical guide paths, and measures the output signals of the plurality of optical-to-electrical conversion elements. It is characterized by comprising a plurality of integrated circuits formed by integrating a plurality of electronic circuits.

Effect> Therefore, the optical signal output from each scintillator constituting the pixel is guided to the photoelectric element of the integrated circuit input section through a light guide path composed of, for example, an optical fiber, and is converted into an electrical signal there. By the way, the converted electrical signal is
A pulse signal corresponding to the number of photons of the input light (the pulse intensity is proportional to the number of photons that cannot be distinguished at the time of arrival at the input part and is considered to arrive at the same time). The signal is processed by the PHA circuit section and the binary counter and output from the output data bus.

<Example> Embodiments of the present invention will be described below based on the drawings.

Figure 1 is a diagram showing the overall configuration of an embodiment of the present invention, with the bottom surface being 0.
．． For example, a scintillator matrix plate 2 is constructed by vertically stacking 1024 sets of 1024 scintillators closely arranged in the horizontal direction, and one side of the prismatic solid scintillator 1 is 3 mm x O, 3 m square. The image receiving surface has an area of 3072 (=0.3×1024) and a square crane. On the back side of the image receiving surface, the end of each scintillator is processed into a convex surface to form a convex lens (see 7 in Figure 3), and the light emitted from scintillator 1 is controlled by the diameter of the cladding prepared corresponding to each scintillator. The light is focused on the receiving end of an optical fiber 8 with a core diameter of 0.14 mm and a core diameter of 0.1 mm (see FIG. 3). These optical fibers 8 are bundled into the optical fiber handle 3 for each set of 1024 scintillators arranged in the horizontal direction, and the light emitted from each scintillator is guided to an integrated circuit 4 having a photodiode as an input element. The optical signal input window of the integrated circuit 4 includes a second
As shown in the figure, 32 x 32 = 1024 photodiodes 5 are arranged in a rectangular array as input elements, and the light emitted from each scintillator is inputted to each one through each optical fiber. In this way, one integrated circuit will have one of 1024 scintillator sets arranged horizontally, and the total number of integrated circuits will be equal to the vertical stacking of such scintillator sets. The number is 1024 corresponding to the number of stages (1024 stages). In order to minimize the mounting area of these 1024 integrated circuits, the light beams are mounted on a mounting board 6 of 32 boards arranged in a louver shape as shown in the figure, so that the parts other than the optical signal input windows overlap diagonally. Thirty-two integrated circuits are mounted on each board with only the signal input window exposed. With this mounting method, the integrated circuit mounting interval on each mounting board can be reduced to 1
511, the area occupied by the mounting portion of 1024 (=32×32) integrated circuits falls within a range of approximately 50 (hs×500 m).

In the overall configuration as described above, the light emitted from each scintillator that is input to the photodiode 5 of the integrated circuit optical signal input section through each optical fiber 8 is converted into an electric pulse signal there. The integrated circuit has an internal circuit configuration as shown in FIG. 3, and the output signal of the photodiode 5 is as follows.
The signal is processed by the pulse height detection amplification circuit section and binary counter section provided for each photodiode, and the incident radiation intensity corresponds to photon energy for each pixel on the imaging surface constituted by each scintillator l. The image is converted into an electrical signal with precision. In this way, a high-sensitivity, high-resolution imaging signal can be obtained.

In the above embodiment, the optical fiber bundle 3
(Fig. 1) is inserted directly into the optical signal input window of the integrated circuit 4, so that the output light of each optical fiber is directly input to each corresponding photodiode. cannot be matched with the optical signal input window, or if for some reason the end of the bundle and the optical signal input window must be separated (for example,
Of course, if a vacuum exists), the output light of the optical fiber can be input to the photodiode via an optical system such as a condenser lens for each optical bundle.

Further, although the above description has been made by measuring the amount of light using a photon counting method, it can also be realized by a normal analog method of measuring the amount of light.

Effect> As is clear from the above description, according to the present invention, the image receiving surface can be divided into small pixels using a large number of scintillators with very small "light receiving" areas, and the light emitted from each scintillator is transmitted through an optical fiber. is guided to the input part of the optical signal integrated circuit, so using the existing optical signal integrated circuit,
A two-dimensional radiographic image having an arbitrary spread can be captured with high sensitivity and high resolution without creating a dividing line.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention. FIG. 2 is a diagram showing the arrangement of photodiodes in the optical signal input section of the integrated circuit used in the above embodiment. FIG. 3 is a diagram showing means for guiding light emitted from the scintillator to the integrated circuit in the above embodiment, and the internal structure of the integrated circuit. 1...Scintillator 2...Scintillator matrix plate 3...Optical fiber bundle 4...Integrated circuit 5...Photodiode 6...Integrated circuit mounting plate 7...Convex lens of scintillator 1 Shape end portion 8...Optical fiber 9...Pulse height detection circuit 10...Binary counter

Claims (3)

[Claims] (1) A device that detects incident radiation with a two-dimensional spread, which includes a plurality of scintillators closely arranged on a radiation detection surface, and a A plurality of light guide paths for guiding the output light of the scintillator to a light-to-electrical conversion element, and a plurality of light-to-electricity conversion elements each having a signal input section arranged with respect to the plurality of light guide paths. 1. A two-dimensional radiation detection device comprising: a plurality of integrated circuits in which a plurality of electronic circuits for measuring output signals of a plurality of photoelectric conversion elements are integrated. (2) The above-mentioned plurality of scintillators are arranged in one direction in the horizontal direction.
2. A two-dimensional radiation detection device according to claim 1, characterized in that a plurality of scintillator rows each consisting of a plurality of scintillators arranged in rows are vertically stacked. (3) The two-dimensional radiation detection device according to claim 1 or 2, wherein the plurality of integrated circuits are arranged in the form of a shutter.