System and method for calibrating the depth of high-energy gamma rays in a detector

Abstract

The present invention relates to a system for calibrating the action depth of high-energy gamma rays in a detector and a method for using the system. Gamma rays emitted by a high-energy gamma ray surface source pass through a collimation system with high-ray blocking capability and are incident from the side wall of a gamma ray detector. The high-energy rays penetrate the detector from the side. The planes where the anode and cathode of the gamma ray detector are located are parallel to a high-energy ray collimation slit determined by the height of a standard pad. The collimation system constrains the high-energy rays to be incident from the side into the detector only through a collimation slit parallel to the anode and cathode planes of the gamma ray detector. The standard gauge block supports the collimation system and adjusts the position of the center plane of the collimation slit. The standard pad supports the upper collimation system and determines the resolution in the depth direction of the detector. A precision lifting platform is used to support the detector and adjust the initial relative position between the high-energy ray detector and the collimation system. The present invention realizes the experimental calibration of the action depth of high-energy gamma rays in the detector.

Description

Technical Field

[0001] The invention belongs to the technical field of gamma ray detection and imaging, and relates to a system for calibrating the action depth of high-energy gamma rays in a detector and a use method thereof. Background Art

[0002] With the development of radiation detection technology, high-energy ray detection has been widely used in medical diagnosis and treatment, safety inspection, nuclear power monitoring and other fields. Large-size radiation detectors have become the main choice for high-end radiation detection applications due to their wide energy response range and high detection efficiency. As the size of detectors expands, ray signal analysis technology is gradually developing in the direction of multi-dimensionality, refinement, and high reliability. Improving the detector's ability to identify and resolve high-energy rays and giving full play to the advantages of large volume have become the key to improving device performance. The development of radiation detectors with three-dimensional position resolution capabilities is currently the research frontier in the field of high-energy ray detection.

[0003] Usually, the two-dimensional projection coordinates of the radiation action site on the anode plane are determined by the detector anode electrode structure, and the action depth of the radiation in the detector, that is, the third-dimensional coordinates of the radiation action site, is calculated by substituting the cathode and anode signals into the theoretical formula. The three-dimensional position resolution level greatly improves the detector's ability to obtain the energy and distribution information of the radiation source, but the method of calculating the third-dimensional coordinates of the radiation action site through theoretical models usually does not consider the influence of the detection crystal properties and the actual readout circuit, and the reliability of the calculated results needs to be improved. It is very necessary to seek a method for determining the third-dimensional coordinates of the radiation action site with high reliability and taking into account the inherent properties of the detection system. Summary of the invention

[0004] Technical issues to be solved

[0005] In order to avoid the shortcomings of the prior art, the present invention proposes a system and method for calibrating the depth of action of high-energy gamma rays in a detector, which takes into account the influence of the inhomogeneity of the detection crystal, the differences between different signal channel ASICs and data processing circuits, and solves the uncertainty and unreliability of the results obtained by theoretical calculation methods in the past.

[0006] Technical Solution

[0007] A system for calibrating the depth of action of high-energy gamma rays in a detector, characterized in that it comprises a high-energy gamma ray surface source 1, two high-energy ray collimation blocks 2, a precision lifting platform 4, a standard gauge block 5 and a standard gasket 6; the two high-energy ray collimation blocks 2 are placed on the precision lifting platform 4, and a standard gasket 6 is provided between the two high-energy ray collimation blocks 2, so that a high-energy ray collimation slit is formed between the two high-energy ray collimation blocks 2; the high-energy gamma ray surface source 1 is placed on one side of the two high-energy ray collimation blocks 2, and the rays are directly facing the standard gasket 6 between the two high-energy ray collimation systems 2; the upper and lower surfaces of the high-energy ray collimation slit are parallel to each other; the standard gaskets are arranged in pairs and placed on the upper surface of the lower collimation system to fully expose the width of the detector in the direction of ray incidence.

[0008] The high-energy ray collimating slit ensures that the intensity of gamma rays whose energy does not exceed a specific value is attenuated to 95% of the incident intensity after passing through the collimating slit.

[0009] The length of the high energy ray collimation slit is determined by the following formula:

[0010]

[0011] The width of the high energy ray collimation slit is consistent with the height of the standard gauge block and the depth resolution capability.

[0012] The height of the high-energy ray collimating block 2 is greater than the distance between the cathode and anode of the detector to be measured.

[0013] The collimator width of the high-energy ray collimation block 2 in the ray incident direction is:

[0014] Collimator width in the direction of incident ray ≥ Collimator width in the direction of incident ray + 2 × standard gasket width

[0015] The materials of the high-energy ray collimation block 2 and the standard pad 6 are lead, pure copper, brass, red copper, tungsten, or tungsten-nickel-iron.

[0016] The working size tolerance of the standard pad and the standard gauge block is less than 0.5 microns, and the adjustment accuracy of the precision lifting platform is less than 5 microns.

[0017] A method for using the system for calibrating the depth of action of high-energy gamma rays in a detector, characterized in that the thickness of the detector to be measured is greater than 1.0 cm, the material of the detector is cadmium zinc telluride, and the electrode material is gold, indium, silver or aluminum; the use steps are as follows:

[0018] Step 1: Determine the following parameters based on the detector being tested:

[0019] 1. The intensity distribution of the high-energy gamma-ray surface source 1 is similar to that of a uniform surface source, and the gamma-ray emission area is larger than the lateral dimension perpendicular to the gamma-ray detector; the energy of the gamma-ray emitted by the radiation source satisfies:

[0020]

[0021] 2. Determine the length of the collimating slit:

[0022]

[0023] 3. Determine the collimator width in the direction of ray incidence:

[0024] The collimator width in the direction of incident rays ≥ the collimator width in the direction of incident rays + 2 × standard gasket width;

[0025] 3. The height of a single collimator is greater than the distance between the cathode and anode of the selected detector;

[0026] 4. Determine the collimation slit width according to the desired detector depth resolution, and the height of the standard gauge block is consistent with the depth resolution capability;

[0027] Step 2: Place the detector to be tested on the other side of the high-energy ray collimation block 2 relative to the high-energy gamma ray surface source 1, and adjust the number of standard blocks to align the collimation slit with the detection part on the side of the detector;

[0028] The planes where the anode and cathode of the gamma-ray detector are located are parallel to the planes where the upper and lower surfaces of the slit of the collimation system are located;

[0029] The arrangement plane of the radiation source is perpendicular to the plane where the center of the slit of the pure tungsten collimation system is located;

[0030] The distance from the radiation source to the collimation system is much greater than the distance from the collimation system to the detector;

[0031] Step 3: Testing the energy response and time response of the detector at the initial position; the initial position is: the plane where the anode / cathode of the detector is located overlaps with the plane where the lower / upper surface of the collimating slit is located;

[0032] Step 4: Fix the detector position unchanged, gradually increase or decrease the number of standard pads supporting the collimation system, and test to obtain the signal of high-energy rays acting on the detector at different depths;

[0033] Step 5: The ray passes through the collimator system and is incident from the side wall of the detector. The anode pixel electrode signal and the cathode plane electrode signal are tested for each photoelectric effect event. According to the ray depth principle, the cathode signal / anode signal is theoretically proportional to the ray incident depth. The ratio of the two is calculated in the test, and a linear function is used to fit the relationship between the ratio of the cathode signal / anode signal and the calibrated depth to obtain the actual depth calibration parameters.

[0034] The gamma rays emitted by the radiation source can pass through the attenuation of the detector, and the penetration intensity is greater than 40%.

[0035] The resistivity of the cadmium zinc telluride material of the detector is 10 9 Ω·cm or above, working leakage current is less than 10nA, bare test 241 The energy resolution of the Am energy spectrum for gamma rays with an energy of 59.5keV is less than 7%. There are no macroscopic defects or grain boundaries inside the crystal, and tellurium inclusions are evenly distributed.

[0036] Beneficial Effects

[0037] The present invention proposes a system for calibrating the action depth of high-energy gamma rays in a detector and a method for using the system, comprising a high-energy gamma ray surface source, a high-energy ray collimation system, a standard gauge block, a standard pad, a large-sized high-energy gamma ray detector, and a precision lifting platform. The gamma rays emitted by the high-energy gamma ray surface source pass through the collimation system with high ray blocking capability and are incident from the side wall of the large-sized gamma ray detector. The high-energy rays have a high probability of penetrating the detector from the side. The planes where the anode and cathode of the large-sized gamma ray detector are located are parallel to the high-energy ray collimation slit determined by the height of the standard pad. The collimation system constrains the high-energy rays to be incident from the side into the detector only from the collimation slit parallel to the anode and cathode planes of the gamma ray detector. The standard gauge block is used to support the collimation system and adjust the position of the center plane of the collimation slit. The standard pad is used to support the upper collimation system and determine the resolution of the detector in the depth direction. The precision lifting platform is used to support the detector and adjust the initial relative position of the high-energy ray detector and the collimation system. The present invention realizes the experimental calibration of the action depth of high-energy gamma rays in the detector.

[0038] The beneficial effects of the present invention are:

[0039] First, the ray depth calibration parameters are obtained from the measured data, taking into account the factors affecting the theoretical calculation model, such as the inhomogeneity of the detection crystal, the differences in different signal channel ASICs and data processing circuits. Compared with the experimental test without depth calibration, which can only obtain the two-dimensional coordinates of the ray action position plane, this experimental method can determine the action depth of gamma rays of different energies in the detector when they are incident vertically, and realize the acquisition of the three-dimensional coordinates of the ray action position space, which provides data support for further accurate energy spectrum correction, device design optimization and high-energy ray Compton imaging based on the ray action depth.

[0040] Second, the experimental system designed by the present invention can be used for various ray depth calibration experiments. The alignment and position control of each plane can be achieved through high-precision standard blocks, standard gaskets, and precision lifting platforms. The experimental process and test methods are more portable, diverse, and reliable, and the experimental and testing costs are controllable.

[0041] Third, the experimental system involved in the present invention can, in principle, obtain its dedicated ray depth calibration parameters by conducting a calibration experiment on a detector before leaving the factory. Therefore, the experimental equipment, as a prototype, can be further upgraded to a dedicated detector parameter testing system by further combining with the in-depth development of the host computer algorithm. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a forward schematic diagram of an experimental device for calibrating the depth of action of high-energy gamma rays in a large-scale gamma-ray detector;

[0043] Figure 2 It is a schematic diagram of the collimation system structure facing the direction of high-energy radiation surface source;

[0044] Figure 3 is a schematic diagram of the detector electrode dimensions;

[0045] Figure 4 It is a schematic diagram of the dimensions of the collimation system;

[0046] Explanation of the symbols of the main components: 1- high energy gamma ray surface source, 2- high energy ray collimation system, 3- large size high energy gamma ray detector, 4- precision lifting platform, 5- standard gauge block, 6- standard gasket. DETAILED DESCRIPTION

[0047] The present invention will now be further described with reference to the embodiments and the accompanying drawings:

[0048] Unless otherwise defined, the technical terms or scientific terms used in this application shall have the usual meanings understood by those skilled in the art. The terms "first", "second", "third", "fourth" and similar words used in the specification and claims of this application do not indicate any order, quantity or importance, but are only used to distinguish different components. Therefore, the features defined as "first", "second", "third", "fourth" may indicate or implicitly include one or more of the features. In the description of the embodiments of this application, unless otherwise specified, the meaning of "multiple" is two or more. The directional terms such as "left", "right", "up", "down", "side" are defined relative to the latitude and longitude illustrated in the accompanying drawings. It should be understood that these directional terms are relative concepts. They are used for description and clarification relative to the latitude and longitude of the experimental device, which may change accordingly according to the change of the latitude and longitude of the experimental device. It does not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the patent of this invention.

[0049] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application. In the following description, reference is made to the drawings that form a part of the present application and show the specific aspects of the embodiments of the present application or can use the specific aspects of the embodiments of the present application in the manner of explanation, wherein the same or similar symbols throughout represent the same or similar elements or elements with the same or similar functions. It should be understood that the embodiments of the present application can be used in other aspects and may include structural or logical changes not depicted in the drawings, and the embodiments are exemplary and are intended to be used to explain the present invention, and cannot be understood as limitations on the present invention. Therefore, the following detailed description should not be understood in a restrictive sense, and the scope of the present application is defined by the appended claims. In addition, it should also be understood that, unless otherwise explicitly stated, the features of the various exemplary embodiments and / or aspects described herein can be combined with each other.

[0050] The design idea of ​​the present invention is:

[0051] The invention discloses a system for calibrating the action depth of high-energy gamma rays in a large-sized detector. The experimental device comprises a high-energy gamma ray surface source, a high-energy ray collimation system, a standard gauge block, a standard cushion block, a large-sized high-energy gamma ray detector and a precision lifting platform.

[0052] It is necessary to strictly define the incident direction of the ray, constrain the ray distribution, and align the incident direction of the ray with the depth of the detector to be calibrated. The test system is built by using a high-energy gamma-ray surface source, a high-energy ray collimation system, standard gauge blocks, standard pads, a large-size high-energy gamma-ray detector, and a precision lifting platform. The gamma rays emitted by the high-energy gamma-ray surface source pass through the collimation system with high ray blocking ability and are incident from the side wall of the large-size gamma-ray detector. The energy of the high-energy ray should be selected to ensure that there is a high probability of penetrating the detector from the side. The plane where the anode and cathode of the large-size gamma-ray detector are located should be parallel to the high-energy ray collimation slit, thereby constraining the high-energy ray to only be incident from the side of the collimation slit parallel to the anode and cathode planes of the gamma-ray detector into the detector. Use standard gauge blocks to support the collimation system and adjust the position of the center plane of the collimation slit. Use standard pads to support the upper collimation system. At the same time, the thickness of the pads determines the resolution of the detector in the depth direction. Use a precision lifting platform to support the detector and adjust the initial relative position of the high-energy ray detector and the collimation system.

[0053] The gamma rays emitted by the high-energy gamma-ray surface source pass through a collimation system with high ray blocking capability and are incident from the side wall of a large-sized gamma-ray detector. The high-energy rays have a high probability of penetrating the detector from the side. The planes where the anode and cathode of the large-sized gamma-ray detector are located are parallel to the high-energy ray collimation slit determined by the height of the standard pad. The collimation system constrains the high-energy rays to be incident from the side into the detector only through the collimation slit parallel to the anode and cathode planes of the gamma-ray detector. The standard gauge block is used to support the collimation system and adjust the position of the center plane of the collimation slit. The standard pad is used to support the upper collimation system and determine the resolution of the detector in the depth direction. The precision lifting platform is used to support the detector and adjust the initial relative position of the high-energy ray detector and the collimation system. The present invention realizes the experimental calibration of the action depth of high-energy gamma rays in the detector.

[0054] In a possible implementation, the material of the detector is cadmium zinc telluride, which is required to have a resistivity of 10 9 Ω·cm or above, working leakage current is less than 10nA, bare test 241 The Am energy spectrum has an energy resolution of less than 7% for gamma rays with an energy of 59.5keV, there are no macroscopic defects and grain boundaries inside the crystal, and tellurium inclusions are evenly distributed; the electrode material of the detector is gold, indium, silver or aluminum; the electrode structure of the detector can ensure that the electric field inside the detector is basically uniform during operation, and when a unit bias is applied to the detection unit, there is a difference in the positive and negative polarity weight potential curves of the detector.

[0055] In a possible implementation, the design criterion of the collimation slit length of the high-energy ray collimation system is to ensure that the intensity of gamma rays with an energy not exceeding a specific value after passing through the collimation slit is attenuated to 95% of the incident intensity, which is determined by the following formula:

[0056]

[0057] In the high-energy ray collimation system, the upper and lower surfaces of the collimation slit are parallel to each other, and the width of the collimation slit is determined by the desired depth resolution of the detector; in the high-energy ray collimation system, the height of a single collimator is greater than the distance between the cathode and anode of the selected detector; in the high-energy ray collimation system, the width of the collimator in the ray incident direction is determined by the following formula: collimator width in the ray incident direction ≥ collimator width in the ray incident direction + 2×standard gasket width

[0058] The collimator is made of lead, pure copper, brass, red copper, tungsten, or tungsten-nickel-iron.

[0059] In one possible implementation, the intensity distribution of the radiation source is approximately similar to that of a uniform surface source, and the gamma ray emission area is larger than a lateral dimension perpendicular to the gamma ray detector; the radiation source can emit gamma rays with relatively high energy.

[0060] In a possible implementation, the planes where the anode and cathode of the gamma-ray detector are located are parallel to the planes where the upper and lower surfaces of the slit of the collimation system are located; the arrangement plane of the radiation source is perpendicular to the plane where the center of the slit of the pure tungsten collimation system is located; the distance from the radiation source to the collimation system is much greater than the distance from the collimation system to the detector; the gamma rays emitted by the radiation source have a high probability of penetrating the detector from the side, and the photoelectric effect energy deposition signal can be collected at any position within the transverse section of the detector, and the energy of the gamma rays emitted by the radiation source satisfies:

[0061]

[0062] In one possible implementation, the standard pads are arranged in pairs and placed on the upper surface of the lower collimation system that fully exposes the width of the detector in the direction of incident radiation; the standard pads are made of the same material as the collimation system, which is lead or pure copper or brass or red copper or tungsten or tungsten-nickel-iron; the thickness of the standard gauge block is consistent with the thickness of the pad, and the number of layers of the standard gauge blocks is adjusted to adjust the alignment of the collimation slit and a specific position on the side of the detector; the working size tolerance of the standard pad and the standard gauge block is less than 0.5 microns, and the adjustment accuracy of the precision lifting platform is less than 5 microns.

[0063] The electrode structure of the detector can ensure that the electric field in the detector is basically uniform during operation. When a unit bias is applied to the detection unit, there is a difference in the potential curves of the positive and negative poles of the detector. The design principle of the collimation slit length of the high-energy ray collimation system is to ensure that the intensity of gamma rays with an energy not exceeding a specific value is attenuated to 95% of the incident intensity after passing through the collimation slit. The intensity distribution of the radiation source is similar to that of a uniform surface source. The gamma ray emission area is larger than the lateral dimension perpendicular to the gamma ray detector. It can emit higher energy gamma rays and has a high probability of penetrating the detector from the side. The photoelectric effect energy deposition signal can be collected at any position in the transverse section of the detector. The working size error or adjustment accuracy of standard pads, standard gauge blocks, and precision lifting platforms is high enough.

[0064] The present invention will be further described below by means of specific embodiments:

[0065] Example 1: Calibration 137 Cs / 60 Systematic and experimental methods for the depth of Co action in large-scale gamma-ray detectors

[0066] In this embodiment, the detector material is cadmium zinc telluride, and the material resistivity is required to be 10 9 Ω·cm or above, working leakage current is less than 10nA, bare test 241The energy resolution of the Am spectrum for gamma rays with an energy of 59.5keV is less than 7%. There are no macroscopic defects or grain boundaries inside the crystal, and the tellurium inclusions are evenly distributed. The electrode material of the detector is gold, and the enabling material of the collimation system is tungsten. The device density is above 93%, and the device density is 18g / cm 3 above.

[0067] In this embodiment, the 137 Cs and 60 Co two kinds of high-energy gamma-ray sources, the source size is about 10mm, and the radiation source position is fixed in the experiment. The three-dimensional size of the detector is 22mm×22mm×15mm (length×width×height), and the detector electrode structure is an 11×11 pixel type. The collimation system consists of two blocks of 30mm×50mm×20mm (length×width×height). The expected spatial resolution of the detector in the depth direction is 1mm, the working size of the standard gauge block is 1mm, the gauge block material is consistent with the collimator material, the working size of the standard pad block is consistent with the standard gauge block, and the number of standard pad blocks is 15. By adjusting the precision lifting platform, the plane where the anode / cathode of the detector is located overlaps with the plane where the lower / upper surface of the collimation slit is located at the initial position, and the energy response and time response of the detector at the initial position are tested. The test is stopped after recording a certain amount of data for a certain period of time. The position of the detector is fixed, and the number of standard pads supporting the collimation system is increased / decreased successively. The signals of high-energy rays acting on the detector at different depths are tested respectively, and the calibration parameters are calculated by the host computer. As Figure 1 As shown, it is a forward schematic diagram of the experimental device when the standard spacer of the collimation system is 9 during the calibration experiment. Figure 2 The collimation system consists of two standard blocks and two collimators. Figure 1 The schematic diagram of the structure facing the incident direction of the ray during the test is shown. Figure 3 The detector electrode dimensions are marked. Figure 4 The dimensions of the collimation system are marked. The working dimension tolerance of the standard spacer and the standard gauge block is <0.5 micron, and the adjustment accuracy of the precision lifting platform is less than 5 microns. Tables 1 and 2 are respectively 137 Cs and 60 Linear function calibration data and its confidence interval obtained from Co experimental calibration.

[0068] Table 1 137 Cs linear calibration parameters and confidence

[0069]

[0070]

[0071]

[0072]

[0073] Note: NAN means that the pixel is deactivated and there is no test data.

[0074] Table 2 60 Co linear calibration parameters and confidence

[0075]

[0076]

[0077]

[0078]

[0079] Note: NAN means that the pixel is deactivated and there is no test data.

[0080] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A system for calibrating the depth of action of high-energy gamma rays in a detector, characterized in that The invention comprises a high-energy gamma-ray surface source (1), two high-energy ray collimation blocks (2), a precision lifting platform (4), a standard gauge block (5) and a standard gasket (6); the two high-energy ray collimation blocks (2) are placed on the precision lifting platform (4), and a standard gasket (6) is arranged between the two high-energy ray collimation blocks (2), so that a high-energy ray collimation slit is formed between the two high-energy ray collimation blocks (2); the high-energy gamma-ray surface source (1) is placed on one side of the two high-energy ray collimation blocks (2), and the ray is directly facing the standard gasket (6) between the two high-energy ray collimation blocks (2); the upper and lower surfaces of the high-energy ray collimation slit are parallel to each other; the standard gaskets are arranged in pairs and are placed on the upper surface of the lower collimation system that fully exposes the width of the detector in the ray incident direction.

2. The system for calibrating the action depth of high-energy gamma rays in a detector according to claim 1, characterized in that: The high-energy ray collimating slit ensures that the intensity of gamma rays whose energy does not exceed a specific value is attenuated to 95% of the incident intensity after passing through the collimating slit.

3. The system for calibrating the action depth of high-energy gamma rays in a detector according to claim 1 or 2, characterized in that: The length of the high energy ray collimation slit is determined by the following formula:

4. The system for calibrating the action depth of high-energy gamma rays in a detector according to claim 1 or 2, characterized in that: The width of the high energy ray collimation slit is consistent with the height of the standard gauge block and the depth resolution capability.

5. The system for calibrating the depth of action of high-energy gamma rays in a detector according to claim 1, characterized in that: The height of the high-energy ray collimating block (2) is greater than the distance between the cathode and anode of the detector to be measured.

6. The system for calibrating the action depth of high-energy gamma rays in a detector according to claim 1 or 5, characterized in that: The collimator width of the high-energy ray collimation block (2) in the ray incident direction is: The collimator width in the ray incident direction ≥ the collimator width in the ray incident direction + 2× the standard gasket width.

7. The system for calibrating the action depth of high-energy gamma rays in a detector according to claim 1 or 5, characterized in that: The materials of the high-energy ray collimation block (2) and the standard gasket (6) are lead, pure copper, brass, red copper, tungsten, or tungsten-nickel-iron.

8. The system for calibrating the action depth of high-energy gamma rays in a detector according to claim 1 or 5, characterized in that: The working size tolerance of the standard gasket and the standard gauge block is <0.5 micron, and the adjustment accuracy of the precision lifting platform is less than 5 microns.

9. A method for using the system for calibrating the depth of action of high-energy gamma rays in a detector according to any one of claims 1 to 8, characterized in that The thickness of the detector under test is greater than 1.0 cm, the material of the detector is cadmium zinc telluride, and the electrode material is gold, indium, silver or aluminum; the use steps are as follows: Step 1: Determine the following parameters based on the detector being tested:

1. The intensity distribution of the high-energy gamma-ray surface source (1) is approximately similar to that of a uniform surface source, and the gamma-ray emission area is larger than the lateral dimension perpendicular to the gamma-ray detector; the energy of the gamma-ray emitted by the radiation source satisfies:

2. Determine the length of the collimating slit:

3. Determine the collimator width in the direction of ray incidence: The collimator width in the direction of incident rays ≥ the collimator width in the direction of incident rays + 2 × standard gasket width; 4. The height of a single collimator is greater than the distance between the cathode and anode of the selected detector; 5. Determine the collimation slit width according to the desired detector depth resolution, and the height of the standard gauge block is consistent with the depth resolution capability; Step 2: placing the detector to be tested on the other side of the high-energy ray collimation block (2) relative to the high-energy gamma ray surface source (1), adjusting the number of layers of the standard gauge block to align the collimation slit with the side detection portion of the detector; The planes where the anode and cathode of the gamma-ray detector are located are parallel to the planes where the upper and lower surfaces of the slit of the collimation system are located; The arrangement plane of the radiation source is perpendicular to the plane where the center of the slit of the pure tungsten collimation system is located; The distance from the radiation source to the collimation system is much greater than the distance from the collimation system to the detector; Step 3: Testing the energy response and time response of the detector at the initial position; the initial position is: the plane where the anode / cathode of the detector is located overlaps with the plane where the lower / upper surface of the collimating slit is located; Step 4: Fix the detector position unchanged, gradually increase or decrease the number of standard gaskets supporting the collimation system, and test and obtain the signal of high-energy rays acting on the detector at different depths; Step 5: The ray passes through the collimator system and is incident from the side wall of the detector. The anode pixel electrode signal and the cathode plane electrode signal are tested for each photoelectric effect event. According to the ray depth principle, the cathode signal / anode signal is theoretically proportional to the ray incident depth. The ratio of the two is calculated in the test, and a linear function is used to fit the relationship between the ratio of the cathode signal / anode signal and the calibrated depth to obtain the actual depth calibration parameters. The gamma rays emitted by the radiation source can be attenuated through the detector, and the penetration intensity is >40%.

10. The method according to claim 9, characterized in that: The resistivity of the cadmium zinc telluride material of the detector is 10 9 Ω·cm or above, working leakage current is less than 10nA, bare test 241 The energy resolution of the Am energy spectrum for gamma rays with an energy of 59.5keV is less than 7%. There are no macroscopic defects or grain boundaries inside the crystal, and tellurium inclusions are evenly distributed.

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