JPH03259569A - Radiation sensor array and radiation image-receiving device - Google Patents

Abstract

PURPOSE:To enhance the concentration resolution of a radiation image-receiving device by a method wherein another electrode is provided on the periphery of split electrodes for forming a unit detecting element in a unit and when the units are arranged for constituting an array, all the split electrodes of the units are arranged in a zigzag form in such a way that they are positioned at equal intervals in the longitudinal direction of the array. CONSTITUTION:A semiconductor crystal 1, split electrodes 2 and a guard electrode 3 are provided on a common electrode 4 as units 5 of a sensor array and a plurality of pieces of these units are arranged on a substrate 6 in a zigzag form. The array is moved and operated in the direction 7 of operation of the sensor array. Operation lines 8 of the array are conformed to a pitch P1 between the split electrodes at the end parts of the adjacent units at the connection parts of units. A pitch between the split electrodes in the individual units is P2. In such a way, a one-dimensional multichannel type semiconductor radiation detector is constituted of unit detecting elements equivalent to the number of the electrodes 2. Radiation 20 is made to incident in a processing deteriorated layer 18 having many traps in such a way and a charge 22 which is generated is collected by the electrode 3 and is earthed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a radiation sensor array and a radiation image receiving device used in medical radiation diagnostic equipment, industrial non-destructive testing equipment, etc. Conventional technologySemiconductor radiation detectors are Scintillation detectors have a higher radiation absorption coefficient than gas detectors, so they are highly sensitive even in minute volumes, and photons of radiation incident on semiconductor crystals are directly converted into charges and output as electrical signals, making scintillation detectors Since it is not necessary to configure the detector with a separate photoelectric conversion system and the detector size can be kept small, its application to various applications is attracting attention. Although it is possible to reduce the size of the detection element and achieve a high positional resolution not found in conventional detectors, as is well known, the X-ray sensor array has a configuration in which a plurality of unit detection elements are arranged in a dimensional array. As the position resolution required for the sensor array increases, the size of the unit detection element must be reduced.1. N, 1 element
Therefore, in a semiconductor X-ray sensor array, a plurality of divided electrodes are arranged in the long plane direction on the radiation receiving surface of a strip-shaped semiconductor crystal to electrically form one semiconductor. Although multiple unit detection elements are formed in a crystal, in this case, there is a manufacturing limit to the length of one semiconductor crystal, so multiple sensor arrays made from one semiconductor crystal are used as a unit. The invention aims to solve the problem by arranging unit units in one dimension to construct an X-ray sensor array of arbitrary length.Now, regarding the factors that affect the characteristics of semiconductor radiation detectors, processing on the cut surface of semiconductor crystal Fig. 6 is a cross-sectional view of the device to explain the influence of the process-damaged layer.
8 is the processing deterioration ML that occurred on the cut surfaces at both ends of the element.
19 is radiation! 21. 22 is an electric power supply, 23 is a briance, and 24 is a high-voltage power source.In response to the radiation 19 incident on the semiconductor crystal 1, a charge 2] is generated.The charge 21 travels through the semiconductor crystal 1 and is collected on the electrode 2. However, the semiconductor crystal 1 has a process-affected layer 18 formed by processing such as cutting. There is a high probability that the charge 22 generated by the radiation 2o incident on the altered layer 18 will be captured by a trap before reaching the electrode l.1. % Therefore, the electric signal output by the charge 22 generated in the process-affected layer 18 has a lower wave height than the electric signal due to the charge 21 generated in other areas. C yo with a vessel
Even if radiation of a single energy is incident, there will be large variations in the wave height of the electrical signal output from the semiconductor detector. Also, the presence of the process-affected layer 18 will also lead to an increase in the surface leakage current between the electrodes 2 and 4. FIG. 7 shows the pulse height spectrum of the 241-Amy line measured with a semiconductor radiation detector in which a process-affected layer exists. In the figure, the horizontal axis is the wave height of the pulse, and the vertical axis is the number of pulses. The photoelectric peak 17 corresponding to the 59.5 keV T-line of 241-Am has a large half-width and a broad peak tailing to the lower wave height side. Furthermore, due to the increase in dark current, the leak component 16 also exhibits a significantly lower energy resolution.

When a transmission image of a subject is captured using an X-ray image receiving device using a sensor array such as the one described above, the energy resolution of the unit detection element is low, so only images with inferior concentration resolution can be obtained. In view of the above problems, the present invention provides a radiation sensor array with excellent energy resolution and reproducibility, and also provides a radiation sensor array with excellent concentration resolution and image quality. An object of the present invention is to provide a radiation image receiving device with excellent reproducibility.Means for solving the problems In order to solve the above problems, the radiation sensor array of the present invention is divided into units to form unit detection elements in unit units. Another method of arranging the unit units to form a sensor array is to form another electrode around the electrode (so that all the divided electrodes of each unit are located at equal intervals in the longitudinal direction of the sensor array). The radiation image receiving apparatus of the present invention has a structure in which the units arranged in a staggered manner are arranged in a staggered manner.The radiation image receiving apparatus of the present invention also has a data processing section for correcting the mutual positional deviation of the units arranged in a staggered manner and displaying an image. The electrodes formed around the working divided electrodes allow the electric charges generated by the incident radiation in the process-affected layer that occurs around the semiconductor crystal (f) to be disposed on the other side of the divided electrodes, that is, closer to the process-affected layer. As a result, the influence of the machining-affected layer is removed from the electrical signal output from the split electrode, and surface leakage current is also prevented from being collected by the split electrode. Therefore, the energy resolution of the unit detection elements improves.Also, since the unit units are arranged in a staggered manner, the pitch between the unit detection elements at the end is the arrangement pitch of the unit detection elements within the unit unit. By arranging the units in a staggered manner, the positional information of the signal obtained from each unit is shifted by the force t.This shift is removed by the data processing section, so it is normal. Embodiments Below, embodiments of the present invention will be described with reference to the drawings. FIG. 1(a) is a perspective view showing an embodiment of the X-ray image receiving apparatus of the present invention. FIG. 1(b) is a cross-sectional view of a unit in the X-ray sensor array of the present invention. In FIG. 1(a), 1 is a semiconductor crystal, and 2 is a divided electrode provided on the X-ray receiving surface of the semiconductor crystal 1. 3 is split electrode 2
This guard electrode is electrically separated from the split electrode 2, but the gap between the electrodes 4 and 4 is provided on the opposite surface of the crystal l to the X-ray receiving surface. The common electric board 5 is a unit, and this unit 5
(A plurality of them are arranged in a staggered manner on the substrate 6.

7 indicates the direction of operation (movement) of the sensor array; cutout 8 indicates the operation line of the sensor array; Pl is the pitch between the end split electrodes of adjacent unit units at the connection part of the unit unit; P2 is the division within the unit unit. Even if a one-dimensional multi-channel semiconductor radiation detector having unit detection elements corresponding to the number of divided electrodes 2 is constructed by the pitch between the electrodes, FIG. 1(b) is the same as that of FIG. 1(a). This is a diagram showing a cross-sectional state of the semiconductor crystal 1, and 19 and 20 indicate radiation 21 incident on the element.
．． 22 is the electric current generated according to the incident radiation 19.20
23 is a preamplifier, 24 is a high-voltage electric current t, and 25 is a boundary between electric lines of force.

By providing the guard electrode 3, a boundary 25 of electric lines of force is created between the divided electrode 2 and the guard electrode 3 within the semiconductor crystal 1, as shown in FIG. 1(b), but both ends of the semiconductor crystal 1 are processed. Even if the altered layer 18 is generated due to processing such as cutting, the lines of electric force of the guard electrode 3 include force that crosses the affected layer I8. (1) The radiation 20 is incident on the process-affected layer 18 with many traps.
The generated charge 22 is collected by the guard electrode 3 and grounded, but the split electrode 2 only contains the charge 21 generated by the radiation 19 incident on the central part of the semiconductor where there are few traps. Since the current is also grounded from the guard electrode 3, it will not adversely affect the output signal from the split electrode 2 (1) In Fig. 1(a), if the units 5 are arranged on one axis instead of in a staggered pattern, the end Because of the guard electrode 3 in the section, the pitch of the joint is larger than the pitch P2 of the divided electrodes 2 in the other unit 5, which further reduces the processing accuracy of the unit.
Considering installation accuracy and absorption of error factors such as thermal expansion, it is necessary to add an additional gap to this pitch. When the AX-ray image is taken, image distortion corresponding to this seam will occur, but this is why we implemented this method. In the example, as shown in the figure, the unit units 5 are fixed to the substrate 6 in a staggered manner.
is made equal to the pitch P2 between the divided electrodes in the unit unit 5. With this configuration, the divided electrodes 2 are arranged at the same pitch in the direction perpendicular to the operation line 8 of the sensor array. The pulse height spectrum of the line is shown.

In the figure, the horizontal axis shows the wave height of the pulse output from the detector, and the vertical axis shows the number of pulses. 59.5keV photoelectric peak 17
Although the half-value width of Although a line sensor array is provided, FIG. 2 is a variation of FIG.
Although the effect is the same as in FIG. 1 and the explanation is omitted, the X-ray image reception of the invention according to claim 2 will be explained using FIG. One embodiment of the apparatus will be described. FIG. 4 is a perspective view showing the X-ray image receiving device of the embodiment. In FIG. 4, 26 is an X-ray sensor array, 27 is an X-ray generating tube, and 28 is a subject 29 The X-ray fan 430 is a data processing section 311; a display section such as 1cRT. A subject 28 is placed between the X-ray sensor array 26 and the X-ray generator 27 described in the previous embodiment.

The X-ray sensor array 26 and the X-ray generator 27 move synchronously in the same direction 7. The X-ray fan beam 29 generated from the four X-ray generators 27 passes through the subject 28 and is irradiated onto each unit 5. The signal from the X-ray sensor array 26 is processed by the data processing unit 30 and output as an image to the display unit 31. When outputting the image, the unit unit 5Q arranged in a staggered manner has a gap (positional shift) in the sensor array movement direction. Although it is necessary to correct this correction, Fig. 5(a) shows a state where the positional deviation is not corrected, that is, an explanatory diagram of the input state to the data processing section. In the same figure, the vertical axis 7 is the sensor Array movement method Horizontal axis 13 is the unit detection element position, 14 is the pitch (positional deviation amount) of the units arranged in a staggered array in the array movement direction (YO), 15 is the image sampling pitch (Yl), and the shaded area is X
Since the pixels in the sensor array that output linear density signals are arranged in a staggered manner,
Even if a pitch (Yo) occurs in the array movement direction, if it is displayed as is, the array movement direction 1 will be displayed as shown in the figure (a).
3, an image is created that is shifted by Yo. Therefore, the sampling pitch (Yl) of the image is set to 1/n times the inter-unit pitch (n is an integer), and the image is output with a shift of n as shown in Figure (b). By doing this, the positional deviation in the array movement direction can be corrected. FIG. 5(b) shows the image matrix after correction.

As described above, an X-ray image receiving device is provided which can take transmission X-ray images with excellent density resolution and good reproducibility without positional deviation. A radiation sensor array in which unit detection elements exhibiting energy resolution are arranged at a constant pitch is provided, and the radiation image receiving apparatus of the present invention can capture high-quality images without distortion.

[Brief explanation of drawings]

FIG. 1(a) is a perspective view showing a radiation sensor array according to an embodiment of the present invention, FIG. 1(b) is a cross-sectional view of a unit constituting the radiation sensor array according to the same embodiment, and FIG. A perspective view showing another embodiment of the invention, FIG. 3 is a characteristic diagram of the radiation sensor array in the embodiment of FIG. 1, FIG. 4 is a perspective view of a radiation image receiving device of an embodiment of the invention, and FIG. (a),
(b) is an explanatory diagram of the data processing method of the X-ray image receiving device in the embodiment of FIG. 4, FIG. 6 is a sectional view of a conventional semiconductor radiation detector, and FIG. 7 is a diagram of a conventional semiconductor radiation detector. It is a characteristic diagram. DESCRIPTION OF SYMBOLS 1...Semiconductor crystal, 2...Divided electrode, 3...Guard electrode, 4...Common electrode, 5...Unit unit, 1
8... Process-affected layer, 19.20... Radiation, 21.
22... Charge, 26... X-ray sensor array, 27.
... X-ray generator, 28... Subject, 29... X-ray fan beam, 30... Data processing section, 31... Display section.

Claims (2)

[Claims] (1) A radiation sensor array in which a plurality of unit units made of semiconductor crystals sensitive to radiation are arranged, the unit units being a plurality of units arranged at a constant pitch in the longitudinal direction on the radiation receiving surface of the semiconductor crystal. It has a plurality of divided electrodes and an electrode surrounding the divided electrodes, and a common electrode for the divided electrodes on a surface opposite to the receiving surface. A radiation sensor array characterized in that the divided electrodes of all the units are arranged at equal intervals in the longitudinal direction. (2) A radiation image receiving device comprising at least a radiation generator, a radiation sensor array, a processing section for data obtained from the radiation sensor array, and a display section for displaying an image obtained through the data processing section, , the radiation sensor array is the radiation sensor array according to claim 1,
The radiation image receiving apparatus is characterized in that the data processing section corrects positional deviations caused by arranging the units of the radiation sensor array in a staggered manner.