Gamma camera and imaging method

Abstract

A gamma camera and imaging method are disclosed. The gamma camera comprises a detection module comprising a multi-layered detection structure, each layer comprising multiple detection units, each configured to receive incident gamma photons and generate projections of the gamma photons. An image reconstruction module, adapted to different imaging requirements, selects portions of the projections for reconstruction, generating a three-dimensional distribution map of gamma photons that meets these requirements. After completing a single scan, the gamma camera can selectively acquire projections with higher spatial resolution, higher sensitivity, and / or different fields of view, thereby simultaneously meeting the requirements for different imaging indicators as much as possible, reducing operation time and steps.

Description

Technical Field

[0001] The present disclosure relates to the field of ray detection technology, and in particular to a gamma camera and an imaging method. Background Art

[0002] With the development of nuclear medicine, radionuclide imaging technology has become increasingly widely used in clinical practice in recent years. Gamma cameras, and the SPECT equipment developed based on their principles, are widely used in the diagnosis and examination of diseases of various organs, including cardiovascular and cerebrovascular diseases, tumors, thyroid glands, liver, and kidneys.

[0003] Traditional gamma cameras and SPECT use conventional parallel-hole collimators to collimate gamma rays, resulting in poor spatial resolution and sensitivity performance indicators. Furthermore, the system is severely restricted by distance, making it difficult to achieve substantial performance improvements. In nuclear medicine clinical diagnosis, different types of parallel-hole collimators are often replaced to achieve different resolution and sensitivity performance indicators for different organs or clinical diseases, and the energy range responses of different collimators are also different. For example, low-energy, high-resolution collimators have higher resolution but lower sensitivity than low-energy general-purpose collimators, making them more suitable for lesion localization diagnosis and diseases requiring high clarity. High-energy general-purpose collimators are suitable for scanning with higher energy labeled radionuclides but have relatively poor resolution. However, almost all collimators cannot simultaneously cover the vast majority of clinical scanning and imaging needs, forcing physicians to frequently change collimators during clinical work. Summary of the Invention

[0004] In view of the above problems, the present invention provides a gamma camera and an imaging method to at least partially solve the above technical problems.

[0005] One aspect of the present disclosure provides a gamma camera, comprising: a detection module comprising a multi-layer detection structure, each layer of the detection structure comprising a plurality of detection units, each of the detection units being configured to receive incident gamma photons and obtain projections of the gamma photons; and an image reconstruction module configured to select portions of the projections for reconstruction according to different imaging requirements, thereby obtaining a three-dimensional distribution map of gamma photons that meets the different imaging requirements.

[0006] Optionally, the relative distance and relative alignment position between the detection structures of each layer of the detection module are adjustable, and the detection structures of each layer and each detection unit can be disassembled and installed.

[0007] Optionally, the image reconstruction module sets a first weight for the projections obtained by different detection units of each layer of the detection structure, and sets a second weight for the set of projections obtained by each layer of the detection structure, and adjusts the first weight and the second weight to achieve the selection of the projections that meet different needs.

[0008] Optionally, the detection units all include scintillation crystals and corresponding photoelectric conversion devices, wherein the scintillation crystals can be multiple scintillation crystal bars distributed in a three-dimensional spatial array, a single scintillation crystal block, or multiple scintillation crystal blocks, and the photoelectric conversion devices can be multiple photomultiplier tubes, or position-sensitive photomultiplier tubes, or multiple avalanche photodiodes, or multiple silicon photomultiplier devices, or multiple multi-pixel photon counters; or the detection units are semiconductor detectors; the composition and size of each detection unit are not exactly the same.

[0009] Optionally, a porous shielding plate is further included, which can be removed or installed at the front end of the detection module to limit the incident direction of the gamma photons.

[0010] Optionally, it also includes: a mechanical adjustment module for adjusting the distance between the gamma photon object under test and the detection module, as well as adjusting the relative distance and relative alignment position between each layer of the detection structure, and disassembling and installing any of the detection structures and the detection unit.

[0011] Optionally, the method further includes: a display module for displaying the three-dimensional distribution image of the gamma photons in real time.

[0012] Another aspect of the present disclosure provides an imaging method, which is applied to the gamma camera as described in the first aspect, comprising: receiving incident gamma photons and obtaining projections of each detection unit incident on each layer of the detection structure; and selecting some of the projections for reconstruction according to different imaging requirements to obtain a three-dimensional distribution map of the gamma photons that meets the different imaging requirements.

[0013] Optionally, according to different imaging requirements, part of the projections are selected for reconstruction to obtain a three-dimensional distribution map of gamma photons that meets different imaging requirements, including: setting a first weight for the projections obtained by different detection units of each layer of the detection structure, and setting a second weight for the set of projections obtained by each layer of the detection structure; according to different imaging requirements, adjusting the first weight and the second weight to achieve the selection of the projections that meet different requirements; and reconstructing based on the selected projections to obtain the three-dimensional distribution of the gamma photons in terms of sensitivity, resolution, edge resolution and imaging field of view.

[0014] Optionally, the method further includes: adjusting the detection structure of each layer of the gamma camera, the number, composition and relative position of each detection unit, and / or adjusting the aperture ratio of the baffle, and / or, when the detection unit includes a scintillation crystal bar, adjusting the distribution density or material density of the scintillation crystal bar, so as to improve the imaging quality of the gamma camera.

[0015] At least one of the above technical solutions adopted in the embodiments of the present disclosure can achieve the following beneficial effects:

[0016] The present disclosure provides a gamma camera having a multi-layer detection structure. Projections can be acquired through a single scan data acquisition. A first weight is assigned to the projections acquired by different detection units in each layer of the detection structure, and a second weight is assigned to the set of projections acquired by each layer of the detection structure for reconstruction. This selectively acquires projections with higher spatial resolution, or higher sensitivity, and or different fields of view, thereby meeting the requirements of as many different imaging indicators as possible. This reduces operation time and steps, thereby improving imaging efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] For a more complete understanding of the present disclosure and its advantages, reference will now be made to the following description taken in conjunction with the accompanying drawings, in which:

[0018] Figure 1 Schematically shows a structural block diagram of a gamma camera according to an embodiment of the present disclosure;

[0019] Figure 2 The following schematically shows a structural diagram of a detection module according to an embodiment of the present disclosure;

[0020] Figure 3 Schematically shows a schematic diagram of the imaging field of view of a detection module according to an embodiment of the present disclosure;

[0021] Figure 4 The following schematically shows a structural diagram of a detection module according to an embodiment of the present disclosure;

[0022] Figure 5 The following schematically shows a structural diagram of a detection module according to another embodiment of the present disclosure;

[0023] Figure 6 The following schematically shows a structural diagram of a detection module according to another embodiment of the present disclosure;

[0024] Figure 7 The following schematically shows a structural diagram of a detection module according to another embodiment of the present disclosure;

[0025] Figure 8 The figure schematically shows the structure of a detection module according to another embodiment of the present disclosure. DETAILED DESCRIPTION

[0026] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0027] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise," "include," etc. used herein indicate the presence of the features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0028] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0029] Figure 1 The structure block diagram of a gamma camera according to an embodiment of the present disclosure is schematically shown.

[0030] like Figure 1 As shown, an embodiment of the present disclosure provides a gamma camera 100 comprising a detection module 110 and an image reconstruction module 120. The detection module 110 comprises a multi-layer detection structure, each layer comprising a plurality of detection units 111. Each detection unit 111 is configured to receive incident gamma photons and obtain projections of the gamma photons. The image reconstruction module 120 is configured to reconstruct selected portions of the projections according to different imaging requirements, thereby obtaining a three-dimensional distribution map of gamma photons that meets the various imaging requirements.

[0031] In the embodiment of the present disclosure, based on the multi-layer detection structure of the detection module 110, multiple projection data can be simultaneously acquired in one gamma photon image data acquisition, thereby reducing the number of data acquisition operations, operation time and operation steps, and improving imaging efficiency and flexibility.

[0032] The relative distance and relative alignment position between the detection structures of each layer of the detection module 110 are adjustable, and the detection structures of each layer and each detection unit can be disassembled and installed.

[0033] In the disclosed embodiment, the image reconstruction module sets a first weight for each projection acquired by different detection units 111 of each layer of the detection structure, and sets a second weight for each set of projections acquired by each layer of the detection structure. By adjusting the first weight and the second weight, the selection of the projections that meet different needs can be achieved. For example, when it is necessary to improve the edge resolution of the three-dimensional distribution map of gamma photons, the first weight of the projection acquired by the detection units 111 of at least one layer of the detection structure relatively close to the edge can be increased, and the edge resolution of the reconstructed three-dimensional distribution map of gamma photons will be correspondingly improved. When it is necessary to perform three-dimensional reconstruction with a smaller imaging field of view, since the imaging field of the detection units 111 closer to the back is smaller, the second weight of at least one layer of the detection structure close to the front end of the detection module 110 can be increased, and the second weight of at least one detection structure close to the back end of the detection module 110 can be reduced, so that the imaging field of the three-dimensional distribution map of gamma photons is reduced.

[0034] The selection and adjustment rules of different performance indicators are as follows:

[0035] (1) Sensitivity: The system sensitivity is improved by selecting the projection obtained from the detection structure layer relatively close to the detected object for reconstruction, or increasing the weight coefficient of the corresponding layer, or changing the detection unit 111 to a structure with a denser distribution of scintillation crystal strips 21, or replacing the scintillation crystals 21 of the detection unit 111 with a material with a higher density, or a crystal with a larger size, or replacing it with a shielding plate with a relatively larger opening rate, or removing the shielding plate. On the contrary, the system sensitivity is reduced by selecting the projection obtained from the detection structure layer relatively far from the detected object for reconstruction, or reducing the weight coefficient of the corresponding layer, or changing the detection unit 111 to a structure with a sparser distribution of scintillation crystal strips 21, or replacing the scintillation crystals 21 of the detection unit 111 with a material with a lower density, or a crystal with a smaller size, or replacing it with a shielding plate with a relatively smaller opening rate, or removing the shielding plate.

[0036] (2) Resolution: The resolution is reduced by selecting the projection obtained from the detection structure layer relatively close to the detected object for reconstruction, or reducing the weight coefficient of the corresponding layer, or replacing it with a baffle with a relatively large aperture for directional alignment, or changing the detection unit 111 to a structure with a sparser distribution of the scintillation crystal bars 21; conversely, the resolution is improved by selecting the projection obtained from the detection structure layer relatively far from the detected object for reconstruction, or increasing the weight coefficient of the corresponding layer, or replacing it with a baffle with a relatively smaller aperture for directional alignment, or changing the detection unit 111 to a structure with a denser distribution of the scintillation crystal bars 21.

[0037] (3) Edge resolution: The edge field resolution is improved by selecting the projections obtained by the detection units 111 that are relatively close to the edge in different detection structure layers for reconstruction, or by increasing the corresponding weight coefficients, or by increasing the number of detection units 111 close to the edge, or by reducing the spacing between detection units 111 close to the edge. Conversely, the edge field resolution is reduced by selecting the projections obtained by the detection units 111 that are relatively far from the edge in different detection structure layers for reconstruction, or by reducing the corresponding weight coefficients, or by reducing the number of detection units 111 close to the edge, or by increasing the spacing between detection units 111 close to the edge.

[0038] (4) Imaging field of view: The projection obtained from the detection structure layer relatively close to the object to be detected is selected for reconstruction, or the direction range of the incident photons is limited by the shielding plate, and the imaging field of view is relatively large. Conversely, the projection obtained from the detection structure layer relatively far from the object to be detected is selected for reconstruction, or the direction range of the incident photons is limited by the shielding plate, and the imaging field of view is relatively small.

[0039] Based on the selection and adjustment rules of the above-mentioned different performance indicators, by adjusting the first weight of each detection unit 111 and the second weight of each layer of detection structure, the influence of the projection obtained by each layer of detection structure and the projection of each detection unit 111 of each layer of detection structure on the reconstructed three-dimensional distribution map of gamma photons is amplified or reduced, thereby obtaining a three-dimensional distribution map display of different sensitivity, resolution, and field of view indicators.

[0040] It should be noted that a detection module 110 may include multiple multi-layer detection structures, thereby constructing various radiation detection structures such as annular, polygonal, linear, curved, and arc-shaped. Each multi-layer detection structure is used to detect gamma photons at different angles to further improve imaging efficiency.

[0041] Figure 2 The schematic diagram shows the structure of the detection module 110 according to an embodiment of the present disclosure.

[0042] like Figure 2 As shown, the detection module 110 includes a multi-layer detection structure, each layer of the detection structure includes a plurality of detection units 111, and each detection unit 111 may include a scintillation crystal 21 and a photoelectric conversion device 22. The scintillation crystal 21 is used to receive incident gamma photons and convert them into visible light signals, and the photoelectric conversion device 22 is used to receive visible light signals and convert them into electrical signals, and then convert the electrical signals into digital signals, and further project them. In addition, each detection unit 111 may be a semiconductor detector. In the embodiment of the present disclosure, the distance between each layer of the detection structure can be relatively adjusted, the relative alignment position can be adjusted, and any layer can be detachable, and any detection unit 111 can be detachable and installable, and the composition and size of any detection unit 111 may not be exactly the same.

[0043] In the embodiment disclosed herein, a baffle plate 23 with a high aperture ratio can be installed at the front end of the detection module 110 to limit the incident direction of the gamma photons. The baffle plate 23 is made of heavy metal and can be freely disassembled. Optionally, the baffle plate 23 can be replaced with a different aperture ratio, a different aperture size, and a different material according to performance requirements, and can be replaced with a parallel hole collimator, a coding plate collimator, and a multi-pinhole collimator with different parameters. Preferably, the aperture ratio of the baffle plate, the size of each hole, and the hole spacing between each hole are all adjustable. According to actual needs and the selection and adjustment rules of the different performance indicators mentioned above, the size and spacing of the holes in different areas of the baffle plate are adjusted separately to improve the imaging quality.

[0044] According to Figure 2 In the detection module 110 shown, the gamma photons released by the radioactive imaging nuclides in the human body 24 pass through the detection module 110 along the incident direction. They are blocked by the baffle 23 and the detection structures of each layer of the detection module 110, and there is a certain probability that they cannot pass through (the so-called photon direction collimation). The image reconstruction module can infer the three-dimensional distribution of gamma photons in the human body based on the reconstruction algorithm according to the statistical projection of the gamma photons received by each detection unit 111 and the distribution probability transmission matrix theoretically received by the detection unit 111.

[0045] Optionally, the detection module 110 may also include: a mechanical adjustment module for adjusting the relative distance between the object being measured for the gamma photons and the detection module 110, as well as adjusting the relative distance and relative alignment position between each layer of the detection structures, and any detection structure and detection unit 111 may be disassembled and installed, and the composition and size of any detection unit 111 may not be exactly the same.

[0046] Optionally, the gamma camera 100 may further include: a display module for displaying the three-dimensional distribution image of the gamma photons in real time. According to the display effect, the user can make adjustments in time according to needs.

[0047] Figure 3 The figure schematically shows the imaging field of view of the detection module 110 according to an embodiment of the present disclosure.

[0048] like Figure 3 As shown, each layer of the detection structure includes multiple detection units 111, and each detection unit 111 includes a scintillation crystal 21 and a corresponding photoelectric conversion device 22. The imaging fields of different layers relative to the baffle 23 are different, and the imaging fields of the detection units 111 in the back layer are smaller. Due to the common collimation effect of the baffle 23 and the front layer detector and the magnification effect of the spacing, the imaging spatial resolution of the detector in the back layer is better. The same reason will cause the imaging sensitivity of the detector in the back layer to be lower.

[0049] Optionally, the scintillation crystals 21 may be a plurality of scintillation crystal bars distributed in a three-dimensional spatial array, or may be a single or multiple scintillation crystal blocks.

[0050] Optionally, the photoelectric conversion device 22 may be a plurality of photomultiplier tubes, or position-sensitive photomultiplier tubes, or a plurality of avalanche photodiodes, or a plurality of silicon photomultiplier devices, or a plurality of multi-pixel photon counters.

[0051] Optionally, the detection unit 111 may be a semiconductor detector.

[0052] Figures 4 to 7 The structural diagrams of the detection module 110 according to one embodiment of the present disclosure are schematically shown respectively.

[0053] Figure 4 The schematic diagram of the structure of the detection module 110 of one embodiment of the present disclosure is shown, the scintillation crystal 21 is a plurality of scintillation crystal blocks, and the photoelectric conversion device 22 is a plurality of photomultiplier tubes distributed in a planar array, or position-sensitive photomultiplier tubes, or a plurality of avalanche photodiodes, or a plurality of silicon photomultiplier devices, or a plurality of multi-pixel photon counters.

[0054] Figure 5 The following schematically illustrates the structure of a detection module 110 according to another embodiment of the present disclosure. The scintillation crystal 21 is a large, monolithic block of scintillation crystal. The photoelectric conversion device 22 is a plurality of discretely distributed photomultiplier tubes, or position-sensitive photomultiplier tubes, or a plurality of avalanche photodiodes, or multiple silicon photomultiplier devices, or multiple multi-pixel photon counters.

[0055] Figure 6 The schematic diagram of the structure of the detection module 110 according to another embodiment of the present disclosure is shown, in which the scintillation crystal 21 is a plurality of scintillation crystal bars distributed in a three-dimensional spatial array, the photoelectric conversion device 22 is a plurality of discretely distributed photomultiplier tubes, or position-sensitive photomultiplier tubes, or a plurality of avalanche photodiodes, or a plurality of silicon photomultiplier devices, or a plurality of multi-pixel photon counters, or the detection unit 111 is a discretely distributed semiconductor detector.

[0056] Figure 7 The schematic diagram of the structure of the detection module 110 according to another embodiment of the present disclosure is shown, in which the scintillation crystal 21 is a plurality of scintillation crystal bars distributed in a three-dimensional spatial array, and the photoelectric conversion device 22 is an array of a plurality of photomultiplier tubes distributed in a planar array, or position-sensitive photomultiplier tubes, or a plurality of avalanche photodiodes, or a plurality of silicon photomultiplier devices, or a plurality of multi-pixel photon counters.

[0057] Figure 8The schematic diagram of the structure of the detection module 110 according to another embodiment of the present disclosure is shown. The composition and number of each detection unit 111 are not exactly the same. The scintillation crystal 21 is a plurality of scintillation crystal bars distributed in a three-dimensional spatial array. The density or material density of the crystal bars of the detection unit 111 may be different. The photoelectric conversion device 22 is a plurality of photomultiplier tubes distributed in a planar array, or position-sensitive photomultiplier tubes, or a plurality of avalanche photodiodes, or a plurality of silicon photomultiplier devices, or a plurality of multi-pixel photon counter arrays. Compared with Figure 7 , Figure 8 The detection units 111 of each layer of the detection module shown can be disassembled and installed at will, the relative spacing between different detection units 111 can be adjusted, and the detection units 111 can be replaced with modules with different scintillation crystal strip density or material density, and the opening rate of the baffle can be partially adjusted relatively.

[0058] According to the gamma camera 100 provided in the embodiment of the present disclosure, a single data acquisition can obtain three-dimensional distribution images of radioactive substances with different spatial resolutions, different imaging sensitivities, different imaging fields, and different energies, thereby simultaneously meeting the imaging requirements of different organs, thereby reducing the user's operation time and operation steps.

[0059] Another aspect of the present disclosure also provides Figure 1 The imaging method of the gamma camera shown includes S1 to S2.

[0060] S1, receiving incident gamma photons and obtaining projections of the incident gamma photons on the detection units 111 of each layer of the detection structure.

[0061] S2, according to different imaging requirements, select some projections for reconstruction to obtain a three-dimensional distribution map of gamma photons that meets different imaging requirements.

[0062] Specifically, S2 includes S201 to S203.

[0063] S201 , setting first weights for projections acquired by different detection units 111 of each layer of the detection structure, and setting second weights for a set of projections acquired by each layer of the detection structure.

[0064] S202: Adjust the first weight and the second weight according to different imaging requirements to select the projection that meets different requirements.

[0065] Specifically, the weight distribution method is as follows:

[0066] P=[α1×P1; α2×P2;...α i ×P i ...; α N ×P N ];

[0067] P i ={β1×P i_1 , β2×P i_2 ,...,β j ×P i_j , ...β M ×P i_M};

[0068] Among them, P i_j represents the projection of the jth detection unit 111 under the i-th layer detector, i=1, 2, ...i..., N, j=1, 2, ...j..., M, P i represents the set of projections of the M detection units 111 contained in the i-th layer, β j represents the first weight of the projection of the jth detection unit 111 of the i-th layer detector in the image reconstruction process, α i Represents the second weight of the i-layer detector projection in the image reconstruction process.

[0069] By adjusting the size of the first weight and the second weight, the influence of the projection obtained by each layer of the detection structure and the projection of each detection unit 111 of each layer of the detection structure on the reconstructed three-dimensional distribution map of gamma photons is magnified or reduced, thereby obtaining a three-dimensional distribution map display with different sensitivity, resolution, and field of view indicators.

[0070] S203 , reconstructing based on the selected projection to obtain a three-dimensional distribution of the gamma photons with different sensitivities, resolutions, edge resolutions, and imaging fields.

[0071] The reconstruction method can adopt the statistical iterative reconstruction algorithm formula:

[0072]

[0073] Among them, p m is the pixel value of the photon on the mth detection unit 111, c mn To obtain the value of the mth row and nth column in the corresponding system transmission matrix, p m =P i_j_m , c mn =C i_j_m_n , the mth detection position refers to the mth minimum detection unit 111 of the jth detection unit 111 under the i-th layer detector, P i_j_m is the pixel value of the mth minimum detection unit 111 of the jth detection unit 111 under the i-th layer detector, C i_j_m_n Represents the contribution of the nth point on the image to the pixel of the mth minimum detection unit 111 of the jth detection unit 111 under the i-th layer detector, Represents the pixel value of the n-th pixel on the image at the k-th iteration, and represents the contribution of the n-th point on the image to the m-th detection position; Represents the pixel value of the j-th pixel on the image at the k+1-th iteration.

[0074] The method utilizes the projections acquired by the detection module 110 of the multi-layer detection structure provided by the present disclosure, and by adjusting the first weight and the second weight of each projection, a three-dimensional distribution image of radioactive material with different spatial resolutions, different imaging sensitivities, and different imaging fields of view can be obtained.

[0075] According to Figure 8 The detection module 110 shown in FIG. 1 has adjustable relative distances and relative alignment positions between detection structures of each layer. The detection structures of each layer and the detection units 111 are removable and installable. The aperture ratio, aperture position, and aperture size of the shielding plate are adjustable. The detection units 111 may also have different compositions and structures. Based on the selection and adjustment rules of different performance indicators of the detection module 110, when imaging using the gamma camera 100, the imaging method may further include operation S3:

[0076] S3: Adjust the number, composition, and relative positions of the detection structures of each layer and each detection unit 111 of the gamma camera 100, and / or adjust the aperture ratio of the shielding plate, and / or, when the detection unit 111 includes a scintillation crystal 21, adjust the distribution density or material density of the scintillation crystal 21, so as to improve the imaging quality of the gamma camera 100.

[0077] By selecting and adjusting the various performance indicators of the detection module 110 and adjusting the structure of the gamma camera 100 itself, various aspects of the performance of the image obtained through projection reconstruction can be adjusted accordingly, further improving imaging quality. Those skilled in the art will appreciate that the features described in the various embodiments and / or claims of this disclosure may be combined and / or coupled in various ways, even if such combinations and / or couplings are not explicitly described in this disclosure. In particular, the features described in the various embodiments and / or claims of this disclosure may be combined and / or coupled in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or couplings are intended to fall within the scope of this disclosure.

[0078] Although the present disclosure has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made to the present disclosure without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents. Therefore, the scope of the present disclosure should not be limited to the above-described embodiments, but should be determined not only by the appended claims but also by the equivalents of the appended claims.

Claims

1. A gamma camera, characterized in that: include: A detection module, comprising a multi-layer detection structure, each layer of the detection structure comprising a plurality of detection units, each of the detection units being configured to receive incident gamma photons and obtain a projection of the gamma photons; An image reconstruction module is used to select some projections for reconstruction according to different imaging requirements to obtain a three-dimensional distribution map of gamma photons that meets different imaging requirements; wherein the image reconstruction module sets a first weight for the projections obtained by different detection units of each layer of the detection structure, and sets a second weight for the set of projections obtained by each layer of the detection structure, and by adjusting the first weight and the second weight, the selection of the projections that meet different requirements can be achieved.

2. The gamma camera according to claim 1, wherein The relative distance and relative alignment position between the detection structures of each layer of the detection module are adjustable, and the detection structures of each layer and each detection unit can be disassembled and installed.

3. The gamma camera according to claim 1, wherein Each of the detection units includes a scintillation crystal and a corresponding photoelectric conversion device, wherein the scintillation crystal is a plurality of scintillation crystal bars distributed in a three-dimensional spatial array, a single scintillation crystal block, or a plurality of scintillation crystal blocks; and the photoelectric conversion device is a plurality of photomultiplier tubes, or position-sensitive photomultiplier tubes, or a plurality of avalanche photodiodes, or a plurality of silicon photomultiplier devices, or a plurality of multi-pixel photon counters; Or the detection unit is a semiconductor detector; The composition and size of each detection unit are not exactly the same.

4. The gamma camera according to claim 1, wherein It also includes a porous shielding plate that can be removed or installed at the front end of the detection module to limit the incident direction of the gamma photons.

5. The gamma camera according to claim 2, wherein: Also includes: The mechanical adjustment module is used to adjust the distance between the gamma photon object and the detection module, adjust the relative distance and relative alignment position between each layer of the detection structure, and disassemble or install any of the detection structure and the detection unit.

6. The gamma camera according to claim 1, wherein Also includes: The display module is used to display the three-dimensional distribution image of the gamma photons in real time.

7. An imaging method, applied to the gamma camera according to any one of claims 1 to 6, characterized in that: include: Receive incident gamma photons and obtain the projections of each detection unit incident on each layer of the detection structure; Setting first weights for projections acquired by different detection units of each layer of the detection structure, and setting second weights for sets of projections acquired by each layer of the detection structure; According to different imaging requirements, adjusting the first weight and the second weight to achieve selection of the projection that meets different requirements; Reconstruction is performed based on the selected projections to obtain a three-dimensional distribution map of the gamma photons with different sensitivities, resolutions, edge resolutions and imaging fields.

8. The imaging method according to claim 7, wherein: The method further comprises: The imaging quality of the gamma camera can be improved by adjusting the detection structure of each layer, the number, composition, and relative position of each detection unit, and / or adjusting the aperture ratio of the baffle, and / or, when the detection unit includes a scintillator crystal bar, adjusting the distribution density or material density of the scintillator crystal bar.

Images