Compton detector space distribution dynamic detection method and system

Abstract

The invention relates to the technical field of medical equipment, and discloses a Compton detector space distribution dynamic detection method and system, and the method comprises the steps: determining a high-radioactivity region of a scanning object; determining a detector distribution space area relative to the scanning object; determining the radioactivity attenuation degree based on the detector distribution space area; determining the arrangement number of Compton detectors in the detector distribution space area based on the radioactivity attenuation degree; the Compton detectors based on the arrangement number are used for detecting the high-radioactivity area; wherein the arrangement number of the Compton detectors is increased along with the increase of the radioactivity attenuation degree. Therefore, detection time can be shortened, image reconstruction artifacts can be reduced, resolution differences of reconstructed images at different angles in a three-dimensional space can be reduced, a more real radionuclide distribution condition can be reflected, a higher-quality radionuclide distribution image can be reconstructed under lower activity, and selectable angle detection information can be provided for reconstructing a three-dimensional image.

Description

Technical Field

[0001] The present invention relates to the technical field of medical equipment, and in particular to a method and system for dynamic detection of spatial distribution of Compton detectors. Background Art

[0002] In the field of modern medicine, nuclear medicine imaging plays an irreplaceable role in disease diagnosis, treatment evaluation and pathological research. It can provide non-invasive information on the distribution of radionuclides inside the human body, which helps to detect tumors early, evaluate organ function and monitor disease progression. However, with the continuous development of nuclear medicine, the requirements for imaging technology are also increasing.

[0003] Compton detector is a gamma-ray detector based on electronic collimation. It has the advantages of high detection efficiency, wide detection energy range, and large imaging field of view. It is currently widely used in astronomical detection and environmental radiation monitoring, and has great development potential in the field of nuclear medicine imaging. However, there are some problems in the current clinical application of Compton detectors. Since the Compton detector reconstructs the image by back-projecting a cone surface into the imaging space based on the detected Compton event, this reconstruction principle leads to artifacts in the reconstructed image, and there are significant differences in the reconstruction resolution on different planes, which seriously affects the reconstruction performance of a single Compton detector in three-dimensional space. Current clinical imaging equipment usually uses tomography to reduce reconstruction artifacts through multi-angle detection, and moves the detection equipment to scan layer by layer to achieve three-dimensional reconstruction. This process results in a long detection cycle and the scanned object needs to bear additional doses. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a Compton detector spatial distribution dynamic detection method and system.

[0005] In a first aspect, the present invention provides a method for dynamic detection of spatial distribution of Compton detectors, comprising: S101, determining a high radioactivity area of ​​a scanned object; wherein a difference in radioactivity between the high radioactivity area and a non-high radioactivity area is higher than an activity threshold; S102, determining a detector distribution spatial region relative to the scan object; S103, determining the degree of radioactive attenuation based on the detector distribution space area; S104, determining the number of the Compton detectors to be arranged in the detector distribution space region based on the radioactive attenuation degree; S105, detecting the high radioactivity area based on the arranged number of Compton detectors; The number of Compton detectors increases as the degree of radioactive attenuation increases.

[0006] Optionally, determining a high radioactivity area of ​​the scanned object includes: Determining the lesion area of ​​the scanned object and determining the radioactive attenuation coefficient; Uniformly surround the lesion area with a target number of pairs of Compton detectors; determining the number of Compton events in a first detection period by the Compton detector of the target number pair; The high radioactivity region is determined based on the number of Compton events and the radioactive attenuation coefficient.

[0007] Optionally, determining the high radioactivity area based on the number of Compton events and the radioactive attenuation coefficient comprises: Determining a high radioactivity location based on the number of Compton events corresponding to each pair of Compton detectors; amplifying the difference between the high radioactivity region and the non-high radioactivity region by an activation function to determine an initial high radioactivity region; The high radioactivity region is determined by combining all the initial high radioactivity regions corresponding to the Compton detectors.

[0008] Optionally, determining a detector distribution spatial region relative to the scanned object includes: Determine a distribution sphere with the imaging space center position of the scanned object as the sphere center; Determining the detector distribution space region based on the distribution sphere; Wherein, the angle between any detector distribution space area and the center of the sphere is equal.

[0009] Optionally, determining the degree of radioactive attenuation based on the detector distribution spatial area includes: The radioactive attenuation degree is determined based on the distance between the high radioactive activity area and the detector distribution space area and the radioactive attenuation coefficient.

[0010] Optionally, the number of arrangements is greater than the number of Compton detectors corresponding to the number of targets.

[0011] Optionally, after the Compton detectors arranged in the number detect the high radioactivity area, the method further includes: Reconstruct a 3D image based on the detection results.

[0012] In a second aspect, the present invention further provides a Compton detector spatial distribution dynamic detection system for implementing the method described in any one of the first aspects; the system comprises: Slide rails are arranged around the inspection bed; At least the arranged number of Compton detectors are fixed on the slide rail and can slide freely along the slide rail.

[0013] Optionally, the slide rail is a spiral slide rail.

[0014] The embodiments of the present invention have the following technical effects: In the detection method provided by the present invention, the high radioactivity area is first determined by a Compton detector, and then the number of Compton detectors in the spatial distribution area of ​​each detector is determined according to the attenuation degree. Since it is not necessary to scan layer by layer through a single Compton detector, the detection time can be effectively shortened and the dose borne by the scanned object can be reduced. By optimizing the spatial distribution of the detector, the image reconstruction artifacts of the Compton detector can be effectively reduced, the difference in the resolution of the reconstructed image at different angles in three-dimensional space can be reduced, and a better and more realistic distribution of radionuclides can be reflected. Multiple Compton detectors can obtain detection information at multiple angles, and higher quality radionuclide distribution images can be reconstructed at lower activities. In addition, the position of the Compton detector can be dynamically adjusted according to the data received in real time by the Compton detector during the detection process, so that selectable angle detection information can be provided for reconstructing a three-dimensional image. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 A schematic flow chart of a method for dynamic detection of spatial distribution of Compton detectors provided by an embodiment of the present invention; Figure 2 A schematic diagram of a high radioactivity area detection scenario provided by an embodiment of the present invention; Figure 3 A schematic diagram of another high radioactivity area detection scenario provided by an embodiment of the present invention; Figure 4 A schematic diagram of the distribution of Compton detectors provided in an embodiment of the present invention; Figure 5 A schematic diagram of the structure of a Compton detector spatial distribution dynamic detection system provided by an embodiment of the present invention.

[0017] Reference numerals A0, high radioactivity area; A1, Compton detector; A2, slide rail; A3, detection bed; A4, scanning object. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0019] Figure 1 A schematic flow chart of a method for dynamic detection of spatial distribution of Compton detectors provided in an embodiment of the present invention. The method can be executed by a controller and includes: S101, determining a high radioactivity area of ​​the scanned object, wherein the difference in radioactivity between the high radioactivity area and the non-high radioactivity area is higher than an activity threshold; Specifically, the scanned object may be a human body, and the embodiments of the present invention are described using the human body as an example. A high radioactivity area refers to an area with high radioactivity, and its notable feature is that the radioactivity in the area is significantly higher than that in other areas (i.e., the difference in radioactivity is higher than the activity threshold).

[0020] In some embodiments, determining a region of high radioactivity in a scanned object includes: Determine the lesion area of ​​the scanned object and determine the radioactive attenuation coefficient.

[0021] The target number of pairs of Compton detectors are evenly placed around the lesion area.

[0022] The number of Compton events in a first detection cycle is determined by a target number of pairs of Compton detectors.

[0023] Areas of high radioactivity are identified based on the number of Compton events and the radioactive attenuation coefficient.

[0024] Specifically, for example, the lesion area of ​​the scanned object is the head. In the process of determining the high radioactivity area of ​​the scanned object, multiple pairs of Compton detectors can be used to surround the lesion area, such as around the head. In practical applications, the attenuation degree of the imaging space can be calculated through the CT image.

[0025] In some embodiments, determining a high radioactivity region based on the number of Compton events and the radioactivity attenuation coefficient comprises: The locations of high radioactivity are determined based on the number of Compton events corresponding to each pair of Compton detectors.

[0026] The difference between the high radioactivity area and the non-high radioactivity area is amplified by the activation function to determine the initial high radioactivity area.

[0027] The high radioactivity region is determined by combining all initial high radioactivity regions corresponding to the Compton detectors.

[0028] After research, it was found that the probability of photons emitted by high radioactivity areas being detected by Compton detectors is inversely proportional to the attenuation degree of the high radioactivity area on the path through the tissue before reaching the Compton detector, and is inversely proportional to the square of the distance between the high radioactivity area and the Compton detector. So for any point P in the tissue, the number of Compton events detected by Compton detector 1 and Compton detector 2 from position P is and The ratios are as follows:

[0029] in, represents the number of Compton events detected by Compton detector 1, represents the number of Compton events detected by Compton detector 1, represents the attenuation degree at the location of Compton detector 1, represents the attenuation degree at the location of Compton detector 2, represents the distance between the high radioactivity area and Compton detector 1, Represents the distance between the high radioactivity area and Compton detector 2. Figure 2 A schematic diagram of a high radioactivity area detection scenario provided by an embodiment of the present invention. Figure 2 As shown in (a), Figure 2 (a) shows the actual location of the high-radioactivity acquisition area (still unknown at this time) A0, and a pair of Compton detectors A1.

[0030] For example, the two Compton detectors measured 9151 and 16106 Compton events respectively, with a ratio of 0.568. Therefore, it can be considered that the high radioactivity area is located in Figure 2 (b) The pixel with a ratio of 0.568. However, the difference between this pixel and other pixels is small, so the activation function

[0031] By amplifying the difference between the pixel with a magnification ratio of 0.568 and other pixels, we can obtain the initial high radioactivity area when the Compton detector count ratio is 0.568, such as Figure 2(c) shows an arc shape. At this time, the exact location of the high radioactivity area cannot be accurately located. Represents the ratio of the number of Compton events.

[0032] Therefore, in the embodiment of the present invention, multiple pairs of Compton detectors are provided. Figure 3 A schematic diagram of another high radioactivity area detection scenario provided by an embodiment of the present invention. Figure 3 As shown in (a), Figure 3 (a) Four pairs of Compton detectors A1 are set (i.e. the target number of pairs can be 4 pairs) to distinguish Figure 3 Different Compton detectors in (a) are distinguished by brackets, A1, 1-8, and the high radioactivity region is indicated as A0. Each pair of Compton detectors can obtain an initial high radioactivity region, such as Figure 3 By combining all the initial high radioactivity regions, the high radioactivity regions can be obtained as Figure 3 (c) As shown. In theory, when the Compton detector count reaches a sufficient level to reduce the statistical error to an acceptable range, the location of the high radioactivity area can be determined by this method. The advantage of this method is that it does not require an imaging reconstruction process and can achieve rapid positioning of the high radioactivity area by relying solely on the Compton detector count information.

[0033] S102: Determine a detector distribution spatial region relative to the scanned object.

[0034] After determining the area of ​​high radioactive activity, the detector distribution space area is further determined.

[0035] In some embodiments, determining a detector distribution spatial region relative to the scanned object includes: The distribution sphere is determined with the imaging space center position of the scanned object as the sphere center.

[0036] The detector distribution space area is determined based on the distribution sphere.

[0037] Among them, the angle between any detector distribution space area and the center of the sphere is equal.

[0038] For example, a sphere with a radius of r and a center position of the imaging space of the scanned object as the center of the sphere can be set. For the 4π imaging space, every 30° can be used as a detector distribution space area. For example, each detector distribution space area is a quadrilateral with equal sides on the sphere, and the angle between the midpoints of the two opposite sides of each detector distribution space area and the center of the sphere can be 30°. The same is true for detector distribution space areas of other shapes. That is, it can be understood that the embodiment of the present invention arranges Compton detectors for each detector distribution space area as a unit. For the center position of the imaging space, the distance between the Compton detector and the center of the sphere is equal. For the high radioactivity area, the distance between different Compton detectors and the high radioactivity area may be the same or different. Figure 4 A schematic diagram of the distribution of Compton detectors provided in an embodiment of the present invention, Figure 4 The scan object A4 shown in the figure may be a human brain, and is therefore shown as an ellipse. The scan object A4 may be located at the center of the imaging space. In the embodiment of the present invention, the Compton detector A1 may be arranged with the center point of the imaging center as the center of the sphere.

[0039] S103. Determine the degree of radioactive attenuation based on the detector distribution space area.

[0040] In some embodiments, determining the extent of radioactivity attenuation based on the detector distribution spatial region includes: The degree of radioactive attenuation is determined based on the distance between the high radioactive activity area and the detector distribution space area and the radioactive attenuation coefficient.

[0041] After determining the detector spatial distribution area, the distance between the detector spatial distribution area and the high radioactivity area can be determined. Generally speaking, the greater the distance, the higher the degree of radioactivity attenuation, that is, the lower the radioactivity, the more difficult it is to detect.

[0042] S104, determining the number of Compton detectors to be arranged in the detector distribution space region based on the radioactive attenuation degree, wherein the number of Compton detectors to be arranged increases as the radioactive attenuation degree increases.

[0043] In some embodiments, the number of arrangements is greater than the number of targets to the number of corresponding Compton detectors.

[0044] On the basis of S103, the embodiment of the present invention determines the number of Compton detectors to be arranged according to the distance between the detector distribution space area and the high radioactivity area. The larger the distance, the greater the degree of radioactive attenuation and the lower the radioactivity, so the higher the number of arrangements. In the above implementation, the embodiment of the present invention determines the high radioactivity area through 8 Compton detectors. In this step, the embodiment of the present invention can detect the high radioactivity area through 36 Compton detectors, such as Figure 4 A schematic diagram of the distribution of Compton detectors provided by an embodiment of the present invention. In the figure, A0 represents a high radioactivity area, and A1 represents a Compton detector.

[0045] Based on the above solution, the embodiment of the present invention has achieved the number of strong and weak Compton detectors based on the radioactivity at the location of the Compton detector.

[0046] S105. Detect the high radioactivity area based on the number of deployed Compton detectors.

[0047] After the Compton detectors are arranged, detection at multiple angles can be achieved through the Compton detectors.

[0048] In summary, the embodiment of the present invention first determines the high radioactivity area through the Compton detector, and then determines the number of Compton detectors in each detector spatial distribution area according to the attenuation degree. Since there is no need to scan layer by layer through a single Compton detector, the detection time can be effectively shortened and the dose borne by the scanned object can be reduced. By optimizing the design of the detector spatial distribution, the Compton detector image reconstruction artifacts can be effectively reduced, the difference in the resolution of the re-edited images at different angles in three-dimensional space can be reduced, and a better and more realistic distribution of radionuclides can be reflected. Multiple Compton detectors can obtain detection information at multiple angles, and higher quality radionuclide distribution images can be reconstructed at lower activities. In addition, the position of the Compton detector can be dynamically adjusted according to the data received in real time by the Compton detector during the detection process, and selectable angle detection information can be provided for reconstructing three-dimensional images.

[0049] In some embodiments, after detecting the high radioactivity area based on the arranged number of Compton detectors, the method further includes: Reconstruct a 3D image based on the detection results.

[0050] Specifically, after the high radioactivity area of ​​the scanned object is detected by the Compton detector, a three-dimensional image can be reconstructed based on the detection result. The reconstructed three-dimensional image can effectively reduce artifacts, and has the characteristics of high resolution and good consistency, which have been described in detail above and will not be repeated here.

[0051] An embodiment of the present invention further provides a Compton detector spatial distribution dynamic detection system, which is used to implement any one of the methods in the above method embodiments. Figure 5 A schematic diagram of the structure of a Compton detector spatial distribution dynamic detection system provided by an embodiment of the present invention, the system includes: The slide rail A2 is arranged around the testing bed A3.

[0052] At least a number of Compton detectors A1 are fixed on the slide rail A2 and can slide freely along the slide rail A2.

[0053] Continue reading Figure 5 In some embodiments, the slide rail A2 is a spiral slide rail.

[0054] In addition, the system further comprises a controller (not shown) electrically connected to the slide rail and / or the detector, and the controller can control the Compton detector A1 to slide along the slide rail A2 to move its position. Figure 5 The A4 in the figure indicates the scanned object.

[0055] Specifically, the Compton detector A1 can be distributed along the axial and circumferential directions of the high radioactivity region A0, increasing the detection angle of the Compton detector A1, which is beneficial to improving the accuracy of the reconstructed three-dimensional image. In this way, the Compton detector A1 can be surrounded by the high radioactivity region A0 to scan the high radioactivity region from multiple angles.

[0056] It should be noted that the terms used in the present invention are only for describing specific embodiments, rather than limiting the scope of the present application. As shown in the present specification, unless the context clearly indicates an exception, the words "one", "a", "a kind of" and / or "the" do not specifically refer to the singular, but may also include the plural. The terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method or device 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, method or device. In the absence of more restrictions, the elements defined by the sentence "include one..." do not exclude the presence of other identical elements in the process, method or device including the elements.

[0057] It should also be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. Unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", etc. should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

Claims

1. A Compton detector spatial distribution dynamic detection method, characterized in that: include: S101, determining a high radioactivity area of ​​a scanned object; wherein a difference in radioactivity between the high radioactivity area and a non-high radioactivity area is higher than an activity threshold; S102, determining a detector distribution spatial region relative to the scan object; S103, determining the degree of radioactive attenuation based on the detector distribution space area; S104, determining the number of the Compton detectors to be arranged in the detector distribution space region based on the radioactive attenuation degree; S105, detecting the high radioactivity area based on the arranged number of Compton detectors; The number of Compton detectors increases as the degree of radioactive attenuation increases.

2. The method according to claim 1, characterized in that Identify areas of high radioactivity in the scanned object, including: Determining the lesion area of ​​the scanned object and determining the radioactive attenuation coefficient; Uniformly surround the lesion area with a target number of pairs of Compton detectors; determining the number of Compton events in a first detection period by the Compton detector of the target number pair; The high radioactivity region is determined based on the number of Compton events and the radioactive attenuation coefficient.

3. The method according to claim 2, characterized in that Determining the high radioactivity area based on the number of Compton events and the radioactive attenuation coefficient includes: Determining a high radioactivity location based on the number of Compton events corresponding to each pair of Compton detectors; amplifying the difference between the high radioactivity region and the non-high radioactivity region by an activation function to determine an initial high radioactivity region; The high radioactivity region is determined by combining all the initial high radioactivity regions corresponding to the Compton detectors.

4. The method according to claim 2, characterized in that: Determining a detector distribution spatial region relative to the scanned object comprises: Determine a distribution sphere with the imaging space center position of the scanned object as the sphere center; Determining the detector distribution space region based on the distribution sphere; Wherein, the angle between any detector distribution space area and the center of the sphere is equal.

5. The method according to claim 2, characterized in that: Determining the degree of radioactive attenuation based on the detector distribution spatial region includes: The radioactive attenuation degree is determined based on the distance between the high radioactive activity area and the detector distribution space area and the radioactive attenuation coefficient.

6. The method according to claim 2, characterized in that The number of arrangements is greater than the number of Compton detectors corresponding to the number of targets.

7. The method according to claim 1, characterized in that After the Compton detectors arranged in the number detect the high radioactivity area, the method further includes: Reconstruct a 3D image based on the detection results.

8. A Compton detector spatial distribution dynamic detection system, characterized in that: Used to implement the method according to any one of claims 1 to 7; the system comprises: Slide rails are arranged around the inspection bed; At least the arranged number of Compton detectors are fixed on the slide rail and can slide freely along the slide rail.

9. The system according to claim 8, characterized in that The slide rail is a spiral slide rail.

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