Gamma ray imaging positioning system based on coded hole collimator
By using coding hole collimator and pixel-shaped surface array detector in the gamma ray imaging system, combined with triangulation, the problem that traditional equipment cannot accurately judge the three-dimensional position of the radioactive source is solved, and higher positioning accuracy and search are achieved efficiency.
Patent Information
- Application Number
- CN202323088447.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-16
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2033-11-16
AI Technical Summary
Traditional gamma-ray imaging equipment cannot accurately determine the three-dimensional position of the radioactive source, resulting in low search efficiency and secondary radiation damage to personnel in application scenarios such as radioactive source search.
The gamma ray imaging positioning system based on the coding hole collimator is adopted to form the coding hole gamma camera through two coding hole collimators and two pixel pattern array detectors, and the two-dimensional position in the coding hole imaging results are used. The incident angle is combined with triangulation method to calculate the distance between the radio source and the detector to achieve three-dimensional positioning of the radio source.
It improves the positioning accuracy of the imaging system, can accurately judge the three-dimensional position of the radioactive source, enhances search efficiency and reduces the risk of radiation damage to personnel.
Smart Images
Figure CN222145239U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of gamma-ray imaging, and in particular to a gamma-ray imaging positioning system based on a coded hole collimator. Background Art
[0002] Gamma-ray imaging technology has important applications in the fields of nuclear facility decommissioning, radioactive source search, nuclear medicine diagnosis and treatment, etc. Coded hole imaging technology, as a multi-hole imaging technology developed on the basis of single pinhole imaging, can improve the detection efficiency of gamma rays while maintaining high imaging accuracy. It has a large imaging field of view, stable reconstructed image quality, and high signal-to-noise ratio. It has become an important technical means in the field of radiation detection imaging.
[0003] Traditional gamma-ray imaging equipment, due to the lack of distance information between the detector and the detector, can generally only display the two-dimensional position of the radiation source in space and cannot make an accurate judgment on its true position and activity. In application scenarios such as searching for radiation sources, it is easy to reduce the search efficiency and cause secondary radiation damage to personnel.
[0004] Therefore, the present application provides a gamma-ray imaging positioning system based on a coded hole collimator to solve the above problems.
[0005] The above contents are only used to assist in understanding the technical solution of the present application and do not constitute an admission that the above contents are prior art. Summary of the invention
[0006] In order to solve the above technical problems, the present application provides a technical solution: a gamma-ray imaging positioning system based on a coded hole collimator, comprising a radiation source that emits gamma rays, a coded hole collimator, a detector and a shielding layer, wherein the coded hole collimators and the detectors are arranged in groups of two, two coded hole collimators are arranged on one side of the radiation source, and two detectors are arranged on the side of the coded hole collimator away from the radiation source, and the shielding layers are multiple in number, and the multiple shielding layers are combined to wrap the coded hole collimators and the detectors.
[0007] As a preferred solution of the present application, the two coded hole collimators are placed in parallel, the centers of the two detectors are coaxial with the centers of the two coded hole collimators, and the two detectors are parallel to each other.
[0008] As a preferred solution of the present application, a plurality of small holes are provided on the coded hole collimator, and the arrangement mode of the plurality of small holes is any one of a uniform redundant array and a modified uniform redundant array.
[0009] As a preferred solution of the present application, it also includes a pixel electrode. A plurality of pixel electrodes are provided on the detector. The plurality of pixel electrodes are arranged in a square array. The shape and size of the pixel electrodes are the same as the shape and size of the small holes.
[0010] As a preferred solution of the present application, the relationship between the number of small holes and the number of pixels on the detector is: when the number of pixels is n×n, the number of apertures is (2n-1)×(2n-1), where n is a positive integer.
[0011] As a preferred solution of the present application, there is a rounded corner between adjacent small holes, and the radius of the rounded corner is 3 / 8 of the side length of the small hole.
[0012] As a preferred solution of the present application, the material used for the coded hole collimator is one of tungsten, tantalum, lead or copper.
[0013] As a preferred solution of the present application, the material of the pixel electrode is one of gold, indium, silver or aluminum.
[0014] As a preferred solution of the present application, the detector material is cadmium zinc telluride.
[0015] As a preferred solution of the present application, the density of the material used in the shielding layer is not less than 7 g / cm 3 materials.
[0016] Compared with the prior art, the novel gamma-ray imaging positioning system based on the coded hole collimator provided in this application has the following advantages:
[0017] The gamma-ray imaging positioning system based on the coded hole collimator provided by the present application utilizes the one-to-one correspondence between the two-dimensional position of the radiation source and the gamma-ray incident angle in the coded hole imaging result, and constructs two adjacent coded hole gamma cameras by utilizing two coded hole collimators and two pixel-type area array detectors. The radiation source is imaged simultaneously, and the two-dimensional position of the radiation source in the image is reconstructed to obtain the angle at which the gamma-rays are incident on the two detectors. The distance between the radiation source and the detector is calculated based on the triangulation method, thereby achieving three-dimensional positioning of the radiation source, thereby improving the positioning accuracy of the imaging system. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 It is a structural schematic diagram of a gamma-ray imaging positioning system based on a coded hole collimator provided by the present application;
[0019] Figure 2 It is a schematic diagram of the principle of coded hole imaging;
[0020] Figure 3 It is a schematic diagram of the ranging principle of the gamma-ray imaging positioning system based on the coded hole collimator provided by the present application;
[0021] Figure 4 It is a schematic diagram of the three-dimensional positioning principle of the gamma-ray imaging positioning system based on the coded hole collimator provided by the present application.
[0022] Description of reference numerals:
[0023] 1. Radiation source; 2. Coded hole collimator; 3. Detector; 4. Shielding layer; 5. Imaging field of view.
[0024] 21. Coded hole collimator on the left; 22. Coded hole collimator on the right; 31. Detector on the left; 32. Detector on the right. DETAILED DESCRIPTION
[0025] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.
[0026] In addition, if the descriptions of "first", "second", etc. are involved in this application, they are only used for descriptive purposes (such as for distinguishing the same or similar elements), and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.
[0027] Please refer to Figure 1 In one embodiment, a gamma-ray imaging positioning system based on a coded hole collimator includes a radiation source 1 that emits gamma rays, a coded hole collimator 2, a detector 3, and a shielding layer 4. The number of coded hole collimators 2 and detectors 3 is two per group. Two coded hole collimators 2 are arranged on one side of the radiation source 1, and two detectors 3 are arranged on the side of the coded hole collimator 2 facing away from the radiation source 1. There are multiple shielding layers 4, and the multiple shielding layers 4 are combined to wrap the coded hole collimators 2 and the detectors 3.
[0028] Optionally, the two coded hole collimators 2 are placed in parallel, the centers of the two detectors 3 are coaxial with the centers of the two coded hole collimators 2 , respectively, and the two detectors 3 are parallel to each other.
[0029] Specifically, the coded hole collimator 2 is used to modulate the incident gamma rays, the detector 3 is specifically a pixel-type area array detector 3, the pixel-type area array detector 3 is used to receive and record the information of the gamma rays, and the shielding layer 4 can be composed of an absorptive material or a scattering shielding material, which is used to limit or eliminate lateral scattering and cross interference, reduce background noise and improve the clarity and accuracy of imaging.
[0030] It can be understood that the gamma-ray imaging positioning system based on the coded hole collimator uses the one-to-one correspondence between the two-dimensional position of the radiation source 1 and the gamma-ray incident angle in the coded hole imaging result, and uses two coded hole collimators 2 and two pixel-type area array detectors 3 to form two adjacent coded hole gamma cameras, and simultaneously images the radiation source 1. By reconstructing the two-dimensional position of the radiation source 1 in the image, the angle of the gamma-ray incident on the two detectors 3 is obtained, and according to the triangulation method, the distance between the radiation source 1 and the detector 3 is calculated to achieve three-dimensional positioning of the radiation source 1, thereby improving the positioning accuracy of the imaging system.
[0031] Optionally, a plurality of small holes are provided on the coded aperture collimator 2, and the arrangement of the plurality of small holes is any one of a uniform redundant array and a modified uniform redundant array.
[0032] It can be understood that the uniform redundant array can provide uniform gamma ray collimation and relatively high spatial resolution, and the modified uniform redundant array further improves the imaging quality by optimizing the layout, thereby increasing the sensitivity and resolution of the system.
[0033] Optionally, a pixel electrode is further included. A plurality of pixel electrodes are arranged on the detector 3. The plurality of pixel electrodes are arranged in a square array. The shape and size of the pixel electrodes are the same as the shape and size of the small holes.
[0034] It can be understood that keeping the pixel electrodes and the pinholes of the same shape and size can make the imaging system symmetrical. In this way, before the gamma rays pass through the pinholes and enter the detector 3, the gamma rays can pass through each pinhole and its corresponding pixel electrode. This symmetry helps to ensure that the imaging results are not distorted or biased.
[0035] Optionally, the relationship between the number of pinholes and the number of pixels on the detector 3 is: when the number of pixels is n×n, the number of apertures is (2n-1)×(2n-1), where n is a positive integer.
[0036] It can be understood that when the number of pinholes is (2n-1)×(2n-1), it can ensure that there is a one-to-one mapping relationship between each pixel and the pinhole on the coded hole collimator 2, which means that during the imaging process, each pixel can accurately correspond to the corresponding pinhole, thereby achieving accurate positioning and imaging of the position of the radiation source 1.
[0037] Optionally, there is a rounded corner between adjacent small holes, and the radius of the rounded corner is 3 / 8 of the side length of the small hole.
[0038] It is understandable that when light passes through a small hole, due to the irregularity of the boundary, a corner effect will occur, that is, the light is inaccurately focused or scattered. By setting rounded corners between adjacent small holes, the corner effect can be alleviated, so that the light can pass through the holes more evenly, improving the clarity and accuracy of imaging.
[0039] Optionally, the material used for the coded hole collimator 2 is one of tungsten, tantalum, lead or copper.
[0040] It is understandable that the reason why the coded hole collimator 2 is made of materials such as tungsten, tantalum, lead or copper is because these materials have high X-ray absorption capacity. In the gamma ray imaging positioning system, the main function of the coded hole collimator 2 is to improve the resolution and contrast of imaging by collimating and filtering the rays. These metal materials have high density and high absorption cross section, can effectively absorb the incident gamma rays, and reduce background noise.
[0041] Optionally, the material of the pixel electrode is one of gold, indium, silver or aluminum.
[0042] It is understandable that the reason why the pixel electrodes on the pixel array detector 3 use materials such as gold, indium, silver or aluminum is because these materials have good electrical conductivity and stability. The pixel electrodes are mainly used for signal reading and conversion, and need to have low resistance, high conductivity and stable performance. Metal materials such as gold, silver, and aluminum have excellent conductive properties, can effectively transmit signals, and are not easily oxidized or corroded.
[0043] Optionally, the material of the detector 3 is cadmium zinc telluride.
[0044] It can be understood that the material of detector 3 is cadmium zinc telluride, which meets the resistivity of 10 9 Ω•cm, the working current is less than 10nA, and at the same time, there are no macroscopic defects, no grain boundaries, and tellurium inclusions are evenly distributed in the crystal. At the same time, silicon materials and germanium materials can also be used to make the detector 3. These semiconductor materials have high resistivity, stable performance and good crystal quality, and are suitable for the manufacture of pixel-type area array detectors 3.
[0045] Optionally, the density of the material used for the shielding layer 4 is not less than 7 g / cm 3 materials.
[0046] It can be understood that the density of the material used in the shielding layer 4 is required to be no less than 7 g / cm 3 This is because high-density materials can effectively absorb more gamma rays and reduce scattering and leakage propagating in the system. The material used for the shielding layer 4 can be one of lead or tungsten.
[0047] In summary, if Figure 1 As shown, in this embodiment, a gamma-ray imaging positioning system based on a coded aperture collimator is provided. The detector 3 adopts a pixel array detector 3, two pixel array detectors 3 are distinguished by a left detector 31 and a right detector 32, and two coded aperture collimators 2 are distinguished by a left coded aperture collimator 21 and a right coded aperture collimator 22;
[0048] The left coded aperture collimator 21 is used to modulate the gamma rays incident to the left detector 31 , the right coded aperture collimator 22 is used to modulate the gamma rays incident to the right detector 32 , and the plurality of shielding layers 4 are used to block external ray interference.
[0049] like Figure 2 As shown, in the coded hole imaging technology, when the detector 3 is n×n pixels and n is a positive integer, the entire imaging field of view 5 is also divided into corresponding n×n regions, each region is connected to the corresponding pixel, and the connecting lines will converge at point O on the central axis. Therefore, according to the two-dimensional position of the reconstructed image of the radiation source 1 on the detector 3, the angle information between the actual position of the radiation source 1 and the central axis can be obtained.
[0050] like Figure 3 and Figure 4 As shown, when the two detectors 3 image the radiation source 1 at different positions, as long as the radiation source 1 is located in the overlapping area of the two fields of view, the distance information between the radiation source 1 and the detector 3 is calculated by triangulation based on the two angle information and the relative position between the two detectors 3. Combined with the two-dimensional position image of the radiation source 1 obtained by the two detectors 3, the three-dimensional positioning of the radiation source 1 can be achieved.
[0051] like Figure 3 As shown, when the angle between the radiation source 1 and the central axis of the left detector 31 is α, the angle between the radiation source 1 and the central axis of the right detector 32 is β, and the distance between the central axes of the two detectors 3 is L, the distance between the radiation source 1 and the detector 3 is
[0052] ;
[0053] Then, based on the reconstructed image of the radiation source 1 , the two-dimensional position distribution of the radiation source 1 in space is obtained, thereby achieving the three-dimensional spatial positioning of the radiation source 1 .
[0054] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, device, article or method including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, device, article or method. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the presence of other identical elements in the process, device, article or method including the element.
[0055] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the principles of the present application should be included in the protection scope of the present application.
Claims
1. A gamma-ray imaging positioning system based on a coded hole collimator, characterized in that: It includes a radiation source that emits gamma rays, a coded hole collimator, a detector and a shielding layer. The coded hole collimators and the detectors are arranged in groups of two. Two coded hole collimators are arranged on one side of the radiation source, and two detectors are arranged on the side of the coded hole collimator away from the radiation source. There are multiple shielding layers, and the multiple shielding layers are combined to wrap the coded hole collimators and the detectors.
2. The gamma-ray imaging positioning system based on a coded hole collimator according to claim 1, characterized in that: The two coded hole collimators are placed in parallel, the centers of the two detectors are coaxial with the centers of the two coded hole collimators respectively, and the two detectors are parallel to each other.
3. The gamma-ray imaging positioning system based on the coded hole collimator according to claim 1, characterized in that: The coded aperture collimator is provided with a plurality of small holes, and the arrangement mode of the plurality of small holes is any one of a uniform redundant array and a modified uniform redundant array.
4. The gamma-ray imaging positioning system based on the coded hole collimator according to claim 3, characterized in that: It also includes pixel electrodes. The detector is provided with a plurality of pixel electrodes, which are arranged in a square array. The shape and size of the pixel electrodes are the same as the shape and size of the small holes.
5. The gamma-ray imaging positioning system based on the coded hole collimator according to claim 4, characterized in that: The relationship between the number of small holes and the number of pixels on the detector is: when the number of pixels is n×n, the number of apertures is (2n-1)×(2n-1), where n is a positive integer.
6. The gamma-ray imaging positioning system based on a coded hole collimator according to claim 3, characterized in that: There is a rounded corner between adjacent small holes, and the radius of the rounded corner is 3 / 8 of the side length of the small hole.
7. The gamma-ray imaging positioning system based on a coded hole collimator according to claim 1, characterized in that: The material used for the coded hole collimator is one of tungsten, tantalum, lead and copper.
8. The gamma-ray imaging positioning system based on a coded hole collimator according to claim 4, characterized in that: The material of the pixel electrode is one of gold, indium, silver or aluminum.
9. The gamma-ray imaging positioning system based on a coded aperture collimator according to claim 1, characterized in that: The detector material is cadmium zinc telluride.
10. The gamma-ray imaging positioning system based on a coded hole collimator according to claim 1, characterized in that: The density of the material used in the shielding layer is not less than 7 g / cm 3 materials.