Method for acquiring readout depth of pet detector, method for acquiring pet image, device, medium and computer program product

Abstract

The application relates to a PET detector readout depth acquisition method, a PET image acquisition method, a computer device, a storage medium and a computer program product, which can improve the calibration operability of a detector crystal. The method comprises the following steps: scanning a scanning object in a field of view to obtain scanning data corresponding to the scanning object and received by a coincidence detector crystal; at least one of the coincidence detector crystals is divided into multiple layers, and each layer corresponds to a DOI readout depth; for each layer of the coincidence detector, image reconstruction is performed according to the scanning data received by the layer to determine a reconstruction effect; the reconstruction effect is related to the starting depth of the coincidence response line of the layer; based on the reconstruction effects of the scanning object, the starting depth of the coincidence response line is adjusted until the reconstruction effects of the scanning object in the reconstruction images match; and the DOI readout depth of each layer is obtained according to the current starting depth of the coincidence response line of each layer of the coincidence detector crystal.

Description

Technical Field

[0001] This application relates to the field of medical device calibration technology, and in particular to a method for obtaining the readout depth of a PET detector, a method for obtaining PET images, an apparatus, a computer device, a storage medium, and a computer program product. Background Technology

[0002] The DOI (Depth-of-interaction) detection capability of a positron emission tomography (PET) system refers to the detector's ability to locate not only its position on the detector plane (xy plane) but also the deposition location of the output photon along the detector's depth (z-axis). To determine the deposition location, the detector crystal can be divided into multiple layers, and the depth information of the output photon can be obtained based on the continuous detector crystal, avoiding the need to cut the detector crystal. This readout method relies on the accurate calibration of the readout depth of each layer within the continuous detector crystal.

[0003] In related technologies, side-incident collimated radiation sources are mainly used to calibrate detector crystals at different positions to obtain readout depths. This calibration method using side-incident sources has very high requirements for the radiation source and can often only calibrate detector crystals in a non-integrated state. For integrated PET systems, it is difficult to set a collimated uniform incident source on the side of each detector crystal to complete the position calibration, resulting in low operability of detector crystal calibration. Summary of the Invention

[0004] Therefore, it is necessary to provide a method for obtaining the readout depth of a PET detector, a method for obtaining PET images, an apparatus, a computer device, a computer-readable storage medium, and a computer program product that can improve the scale operability of the detector crystal, in order to address the above-mentioned technical problems.

[0005] In a first aspect, this application provides a method for obtaining the readout depth of a PET detector, applied to a positron emission tomography (PET) system, the method comprising:

[0006] The object located within the field of view is scanned to obtain scan data corresponding to the object received by the coincidence detector crystal; at least one of the coincidence detector crystals is divided into multiple layers, each layer corresponding to a DOI readout depth.

[0007] For each layer of the coincidence detector, image reconstruction is performed based on the scan data received by that layer, and the reconstruction effect of the scanned object in the reconstructed image is determined; the reconstruction effect is related to the starting depth of the coincidence response line of that layer.

[0008] Based on the reconstruction results of the scanned object, the starting depth of the response line is adjusted until the reconstruction results of the scanned object in each reconstructed image match.

[0009] The DOI readout depth of each layer is obtained based on the current starting depth of the coincidence response line of each layer of the coincidence detector crystal.

[0010] In one embodiment, scanning the object located within the field of view to obtain scanning data corresponding to the scanned object received by the detector crystal includes:

[0011] When a scanning object located off-center within the field of view rotates around a preset rotation center, the scanning object is scanned to obtain scanning data corresponding to the scanning object received by the detector crystal.

[0012] The image reconstruction based on the scan data received by this layer includes:

[0013] The image is reconstructed based on the scan data received by each coincidence detector crystal in that layer.

[0014] In one embodiment, determining the reconstruction effect of the scanned object in the reconstructed image includes:

[0015] The distance between the scanned object carrying the radioactive tracer and the preset rotation center is determined based on the intensity of each pixel in the reconstructed image and the distance of each pixel from the preset rotation center; the intensity of the pixel is positively correlated with the concentration of the radioactive tracer.

[0016] The location of the scanned object in the reconstructed image is determined based on the distance between the scanned object and the preset rotation center, and the reconstruction effect is determined based on the location of the scanned object.

[0017] In one embodiment, determining the distance between the scanned object carrying the radioactive tracer and the preset rotation center based on the intensity of each pixel in the reconstructed image and the distance of each pixel from the preset rotation center includes:

[0018] A scatter plot is generated based on the intensity of each pixel in the reconstructed image and the distance between each pixel and the preset rotation center, with the pixel intensity as the ordinate and the distance between each pixel and the preset rotation center as the abscissa.

[0019] Curve fitting is performed on the scatter plot, and the mapping relationship between the distance between the pixel and the preset rotation center and the intensity of the pixel is determined based on the curve fitting result.

[0020] The distance between the pixel and the preset rotation center when the intensity is at its strongest is determined based on the mapping relationship, and is used as the distance between the scanned object and the preset rotation center.

[0021] In one embodiment, determining the reconstruction effect of the scanned object in the reconstructed image includes:

[0022] Determine the location of the scanned object in the reconstructed image, and determine the reconstruction effect of the scanned object based on its location;

[0023] And / or,

[0024] Determine the size of the scanned object in the reconstructed image, and determine the reconstruction effect of the scanned object based on the size of the scanned object.

[0025] In one embodiment, adjusting the starting depth of the response line based on the reconstruction results of the scanned object until the reconstruction results of the scanned object match in each reconstructed image includes:

[0026] In the multilayer of the detector crystal, a target layer is identified as a reference, and the reconstructed image corresponding to the target layer is used as a reference reconstructed image.

[0027] For layers other than the target layer in the coincidence detector crystal, if the reconstruction effect of the scanned object in the reconstructed image of that layer does not match the reconstruction effect in the reference reconstructed image, the starting depth of the corresponding coincidence response line is adjusted until the reconstruction effect matches.

[0028] Secondly, this application also provides a method for acquiring PET images, the method comprising:

[0029] The phantom located within the field of view is scanned to obtain scan data corresponding to the phantom received by the coincidence detector crystal; at least one of the coincidence detector crystals is divided into multiple segments, each segment corresponding to different DOI information;

[0030] For each segment of the coincident detector crystal, an image of the phantom is obtained based on the scan data received from that segment;

[0031] Based on the image of the phantom, the DOI information corresponding to each segment is corrected;

[0032] Reconstruction is performed on the data of the scanned object based on the corrected DOI information to obtain a PET image of the scanned object.

[0033] Thirdly, this application also provides a readout depth acquisition device for a PET detector, applied to a positron emission tomography (PET) system, the device comprising:

[0034] The scanning module is used to scan the object located within the field of view and obtain the scanning data corresponding to the object received by the coincidence detector crystal; at least one of the coincidence detector crystals is divided into multiple layers, each layer corresponding to a DOI readout depth;

[0035] The image reconstruction module is used to reconstruct the image for each layer of the coincidence detector based on the scan data received by that layer, and to determine the reconstruction effect of the scanned object in the reconstructed image; the reconstruction effect is related to the starting depth of the coincidence response line of that layer.

[0036] The starting depth adjustment module is used to adjust the starting depth that matches the response line based on the reconstruction effect of the scanned object in each reconstruction image until the reconstruction effect of the scanned object matches in each reconstruction image.

[0037] The calibration module is used to obtain the DOI readout depth of each layer based on the current starting depth of the coincidence response line of each layer of the coincidence detector crystal.

[0038] Fourthly, this application also provides a PET image acquisition device, the device comprising:

[0039] The scanning data acquisition module is used to scan the phantom located within the field of view to obtain the scanning data corresponding to the phantom received by the coincidence detector crystal; at least one of the coincidence detector crystals is divided into multiple segments, each segment corresponding to different DOI information;

[0040] The image acquisition module is used to acquire an image of the phantom for each segment of the coincidence detector crystal based on the scan data received for that segment;

[0041] The correction module is used to correct the DOI information corresponding to each segment based on the image of the phantom;

[0042] The PET image acquisition module is used to reconstruct the data of the scanned object based on the corrected DOI information and acquire the PET image of the scanned object.

[0043] Fifthly, this application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to perform the following steps:

[0044] The object located within the field of view is scanned to obtain scan data corresponding to the object received by the coincidence detector crystal; at least one of the coincidence detector crystals is divided into multiple layers, each layer corresponding to a DOI readout depth.

[0045] For each layer of the coincidence detector, image reconstruction is performed based on the scan data received by that layer, and the reconstruction effect of the scanned object in the reconstructed image is determined; the reconstruction effect is related to the starting depth of the coincidence response line of that layer.

[0046] Based on the reconstruction results of the scanned object, the starting depth of the response line is adjusted until the reconstruction results of the scanned object in each reconstructed image match.

[0047] The DOI readout depth of each layer is obtained based on the current starting depth of the coincidence response line of each layer of the coincidence detector crystal.

[0048] Sixthly, this application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to perform the following steps:

[0049] The phantom located within the field of view is scanned to obtain scan data corresponding to the phantom received by the coincidence detector crystal; at least one of the coincidence detector crystals is divided into multiple segments, each segment corresponding to different DOI information;

[0050] For each segment of the coincident detector crystal, an image of the phantom is obtained based on the scan data received from that segment;

[0051] Based on the image of the phantom, the DOI information corresponding to each segment is corrected;

[0052] Reconstruction is performed on the data of the scanned object based on the corrected DOI information to obtain a PET image of the scanned object.

[0053] Seventhly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the following steps:

[0054] The object located within the field of view is scanned to obtain scan data corresponding to the object received by the coincidence detector crystal; at least one of the coincidence detector crystals is divided into multiple layers, each layer corresponding to a DOI readout depth.

[0055] For each layer of the coincidence detector, image reconstruction is performed based on the scan data received by that layer, and the reconstruction effect of the scanned object in the reconstructed image is determined; the reconstruction effect is related to the starting depth of the coincidence response line of that layer.

[0056] Based on the reconstruction results of the scanned object, the starting depth of the response line is adjusted until the reconstruction results of the scanned object in each reconstructed image match.

[0057] The DOI readout depth of each layer is obtained based on the current starting depth of the coincidence response line of each layer of the coincidence detector crystal.

[0058] Eighthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the following steps:

[0059] The phantom located within the field of view is scanned to obtain scan data corresponding to the phantom received by the coincidence detector crystal; at least one of the coincidence detector crystals is divided into multiple segments, each segment corresponding to different DOI information;

[0060] For each segment of the coincident detector crystal, an image of the phantom is obtained based on the scan data received from that segment;

[0061] Based on the image of the phantom, the DOI information corresponding to each segment is corrected;

[0062] Reconstruction is performed on the data of the scanned object based on the corrected DOI information to obtain a PET image of the scanned object.

[0063] Ninthly, this application also provides a computer program product, including a computer program that, when executed by a processor, performs the following steps:

[0064] The object located within the field of view is scanned to obtain scan data corresponding to the object received by the coincidence detector crystal; at least one of the coincidence detector crystals is divided into multiple layers, each layer corresponding to a DOI readout depth.

[0065] For each layer of the coincidence detector, image reconstruction is performed based on the scan data received by that layer, and the reconstruction effect of the scanned object in the reconstructed image is determined; the reconstruction effect is related to the starting depth of the coincidence response line of that layer.

[0066] Based on the reconstruction results of the scanned object, the starting depth of the response line is adjusted until the reconstruction results of the scanned object in each reconstructed image match.

[0067] The DOI readout depth of each layer is obtained based on the current starting depth of the coincidence response line of each layer of the coincidence detector crystal.

[0068] In a tenth aspect, this application also provides a computer program product, including a computer program that, when executed by a processor, performs the following steps:

[0069] The phantom located within the field of view is scanned to obtain scan data corresponding to the phantom received by the coincidence detector crystal; at least one of the coincidence detector crystals is divided into multiple segments, each segment corresponding to different DOI information;

[0070] For each segment of the coincident detector crystal, an image of the phantom is obtained based on the scan data received from that segment;

[0071] Based on the image of the phantom, the DOI information corresponding to each segment is corrected;

[0072] Reconstruction is performed on the data of the scanned object based on the corrected DOI information to obtain a PET image of the scanned object.

[0073] The aforementioned PET detector readout depth acquisition method, PET image acquisition method, apparatus, computer equipment, storage medium, and computer program product can scan a scanned object located within the field of view to obtain scan data corresponding to the scanned object received by the coincidence detector crystal. At least one of the coincidence detector crystals is divided into multiple layers, each corresponding to a DOI readout depth. For each layer of the coincidence detector, image reconstruction can be performed based on the scan data received by that layer, and the reconstruction effect of the scanned object in the reconstructed image can be determined. The reconstruction effect is related to the starting depth of the coincidence response line of that layer. Then, based on the reconstruction effects of each scanned object, the starting depth of the coincidence response line can be adjusted until the reconstruction effects of the scanned object in each reconstructed image match. Based on the current starting depth of the coincidence response line of each layer of the coincidence detector crystal, the DOI readout depth of each layer is obtained. In this embodiment, image reconstruction is performed using scanning data from multiple layers of the coincidence detector crystal. By comparing the reconstruction effect of the scanned object in different reconstructed images, the starting depth of the coincidence response line is adjusted. By aligning the reconstruction effects between different reconstructed images, the DOI readout depth of each layer of the coincidence detector crystal can be indirectly calibrated in the integrated PET system without relying on a high-quality radiation source, effectively improving the operability of the detector crystal calibration. Attached Figure Description

[0074] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0075] Figure 1 This is a flowchart illustrating a method for obtaining the readout depth of a PET detector in one embodiment.

[0076] Figure 2 This is a schematic diagram of an annihilation event in a PET system according to one embodiment;

[0077] Figure 3a This is a schematic diagram of the position of a point source before the scale in one embodiment;

[0078] Figure 3b This is a schematic diagram of the position of a point source after scaling in one embodiment;

[0079] Figure 4 This is a flowchart illustrating one step in determining the reconstruction effect in one embodiment;

[0080] Figure 5a One embodiment is a reconstructed image;

[0081] Figure 5b This is a scatter plot in one embodiment;

[0082] Figure 6 This is a flowchart illustrating a PET image acquisition method in one embodiment;

[0083] Figure 7 This is a structural block diagram of a detector crystal depth reading device in one embodiment;

[0084] Figure 8 This is a structural block diagram of a PET image acquisition device in one embodiment;

[0085] Figure 9 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0086] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0087] In one embodiment, such as Figure 1 As shown, a method for obtaining the readout depth of a PET detector is provided. This embodiment illustrates the application of this method to a positron emission tomography (PET) system. In this embodiment, the method includes the following steps:

[0088] S101, the scanning object located within the field of view is scanned to obtain the scanning data corresponding to the scanning object received by the coincidence detector crystal; at least one of the coincidence detector crystals is divided into multiple layers, each layer corresponding to a DOI readout depth.

[0089] To better understand this embodiment, the relevant information about the positron emission tomography (PET) system is introduced below. Specifically, the positron emission tomography (PET) system uses the coincidence detection of a pair of gamma photons with the same energy but opposite directions generated by positron annihilation to determine the physical location of the annihilation. When using the PET system, a drug containing a radionuclide is injected into the object being scanned. The radionuclide decays within the object, producing positrons. These positrons annihilate with electrons in the object, generating two back-to-back gamma photons. These two gamma photons are incident on the surface of the detector crystal. After energy deposition in a crystal strip, the position of that strip is the crystal position where the gamma photons were detected, as output by the system. For a gamma photon pair, the line connecting the two detector crystals with energy deposition is called the coincidence response line (LOR). In practical applications, any line connecting a pair of coincidence detector crystals can form a coincidence response line. The location of the radiation source can generally be considered to be on the coincidence response line, i.e., on the line connecting the gamma photon pair incident on the coincidence detector crystal. By utilizing the coincidence response line and performing relevant data processing, a reconstructed image can be obtained.

[0090] In this embodiment, the scanning object can be positioned within the field of view (FOV) of the PET system. The scanning object can be a complete phantom or a part of a phantom.

[0091] In some embodiments, the scanning object can be positioned off-center within the field of view, also known as the circumferential offset. For example, a small phantom (such as a point source with radioactivity) can be positioned at the circumferential offset, in which case the scanning object is the phantom. Alternatively, a sufficiently large phantom can be placed at the center of the field of view of the positron emission tomography system so that part of the phantom is located at the circumferential offset, such as placing a uniform phantom with a certain diameter (such as directly larger than a threshold) at the center, in which case part of the phantom is located at the circumferential offset within the field of view.

[0092] Specifically, when the annihilation reaction (also known as the annihilation event) occurs entirely at the center of the field of view, for example, when it occurs in a field of view such as... Figure 2 At the center of the field of view, A, the crystal pairs directly above and below each receive a gamma ray. At this point, the DOI detection capability is weak, making it difficult to determine the depth at which the ray acts on the detector crystal. However, when the annihilation reaction occurs at the circumferentially off-center location, for example, at... Figure 2 At the circumferentially eccentric position B shown, the upper and lower crystals have a certain tilt angle relative to the emitted gamma rays. The gamma rays may act on the entire depth of the crystal. At this time, the DOI detection capability of the coincidence detector crystal is strong, and it can more accurately determine where the annihilation event occurred in the crystal.

[0093] Based on this, in this step, the object to be scanned can be positioned off-center within the field of view, or an object of a certain size can be placed at the center, so that at least a portion of the gamma rays emitted during the annihilation reaction can be collected by the coincidence detector crystal. Thus, the coincidence detector crystal can receive scan data corresponding to the scanned object; this scan data is also called the coincidence data of the detector crystal. The PET system can include multiple coincidence detector crystals. A coincidence detector crystal can be understood as the detector crystal whose corresponding coincidence response line is to be determined during subsequent image reconstruction. A coincidence detector crystal can be divided into multiple layers. In some examples, the coincidence detector crystal can be a multi-layered crystal formed of different materials. Each layer of the coincidence detector crystal can correspond to a DOI readout depth, and each layer can acquire corresponding scan data.

[0094] In some alternative embodiments, the position of the scanned object within the field of view can be fixed or changed throughout the scanning process. For example, the scanned object may appear at one or more fixed circumferential eccentricities within the field of view, or the scanned object may rotate around a certain center at the circumferential eccentricity.

[0095] In some embodiments, the scanning object can be a point source with a radial shape, which is small enough to have high reconstruction position accuracy; of course, other scanning objects that can be reconstructed to obtain clear boundaries or positions can also be selected to facilitate the alignment of subsequent reconstruction results, such as rod-shaped, barrel-shaped or other shaped phantoms.

[0096] S102, for each layer of the coincidence detector, image reconstruction is performed based on the scan data received by that layer, and the reconstruction effect of the scanned object in the reconstructed image is determined; the reconstruction effect is related to the starting depth of the coincidence response line of that crystal layer.

[0097] After the coincidence detector crystal receives the corresponding gamma rays and obtains the scan data corresponding to the scanned object, the corresponding layer in the coincidence detector crystal can obtain the corresponding scan data. In this step, for each layer in the coincidence detector crystal, image reconstruction can be performed separately using the scan data of that layer. In other words, image reconstruction can be performed based solely on the scan data of that layer to obtain the reconstructed image corresponding to that layer. During image reconstruction, the reconstructed image can be obtained through reconstruction algorithms, such as OSEM (Ordered Subset Expectation Maximization) and FBP (Filtered Back Projection); or, other methods such as direct back projection can also be used to obtain the reconstructed image.

[0098] Then, the reconstruction effect of the scanned object in the reconstructed image can be determined. Specifically, the reconstruction effect indicates whether the image content presented by the scanned object in the reconstructed image matches the information presented by the scanned object in the real world. In practical applications, the reconstruction effect of the scanned object in the reconstructed image can be characterized by specific parameters, such as the position and / or size of the scanned object in the reconstructed image (also known as the size of the scanned object in the reconstructed image). When the position and size indicated by the scanned object in the reconstructed image match the position and size of the scanned object in the real world (e.g., the same or the difference is less than a threshold), it can be considered that the reconstructed image can truly reflect the situation of the scanned object, and the reconstruction effect is excellent.

[0099] The reconstruction effect of the scanned object in the reconstructed image is related to the starting depth of the coincidence response line of the corresponding layer in the coincidence detector crystal (that is, the specified layer that provides the scan data corresponding to the reconstructed image). When the position of the coincidence response line changes, that is, when the starting depth of the coincidence response line changes, the parameters set by the algorithm in the image reconstruction will also change, thereby changing the reconstruction effect of the scanned object.

[0100] S103, based on the reconstruction effects of each scanned object, adjust the starting depth of the response line until the reconstruction effects of the scanned object in each reconstructed image match.

[0101] In practical applications, for reconstructed images based on scan data from each layer, since they are all reconstructed from the same scanned object, theoretically the reconstructed effect of the scanned object in each reconstructed image should match. Specifically, for example, the same scanned object should exhibit the same reconstructed effect in different reconstructed images, such as the size or position of the scanned object being the same in each reconstructed image. However, due to the influence of the coincidence response line start depth, if the start depth of the coincidence response line does not correspond to the DOI readout depth of the coincidence detector crystal layer, the reconstructed effect of the scanned image in different reconstructed images will be different.

[0102] In this step, the reconstruction effects of the scanned object in each reconstructed image can be compared. Based on the comparison results, the starting depth of the coincidence response lines of at least one layer of the detector crystal is adjusted. In some optional embodiments, when adjusting the starting depth of the coincidence response lines, the starting depth of the coincidence response lines of some layers can be adjusted, or the starting depth of the coincidence response lines of each layer of the coincidence detector crystal can be adjusted. The specific number of coincidence response lines to be adjusted can be determined according to the actual situation. After adjusting the starting depth of the coincidence response lines, steps S101 and S102 can be repeated, that is, the scanned object located off-center within the field of view is scanned again. Image reconstruction is performed separately based on the scan data of each layer in the coincidence detector crystal, and the reconstruction effects of the scanned object in each reconstructed image are compared. The adjustment process is repeated until the reconstruction effects of the scanned object in each reconstructed image match.

[0103] S104. Based on the current starting depth of the coincidence response line of each layer of the coincidence detector crystal, the DOI readout depth of each layer is obtained.

[0104] When the reconstruction results of the scanned object match in each reconstructed image, the current starting depth of the coincidence response line of each layer can be determined to match its DOI readout depth. Based on the current starting depth of the coincidence response line, accurate image reconstruction of the scanned object can be performed. Therefore, the DOI readout depth of each layer of the coincidence detector crystal can be obtained from the current starting depth of the coincidence response line of each layer. Specifically, the current starting depth of the coincidence response line of each layer can be used as the DOI readout depth of each layer of the coincidence detector crystal.

[0105] Figure 3a A schematic diagram of the position of the point source before the scale is shown. Figure 3b A schematic diagram of the point source position after recalibration is shown. In this example, the point source is located at a position 20cm off-center (i.e., the distance between the point source and the center of the field of view is 20cm). As shown in the figure, after recalibration, the position of the point source is more consistent with the position of the CT image.

[0106] The aforementioned PET detector readout depth acquisition method, applied to a positron emission tomography (PET) system, can scan an object located within the field of view, obtaining scan data corresponding to the scanned object received by a coincidence detector crystal. At least one of the coincidence detector crystals is divided into multiple layers, each corresponding to a DOI readout depth. For each layer of the coincidence detector, image reconstruction can be performed based on the scan data received by that layer, and the reconstruction effect of the scanned object in the reconstructed image can be determined. The reconstruction effect is related to the starting depth of the coincidence response line of that layer. Then, based on the reconstruction effects of the scanned object, the starting depth of the coincidence response line can be adjusted until the reconstruction effects of the scanned object in each reconstructed image match. The DOI readout depth of each layer is obtained based on the current starting depth of the coincidence response line of each layer of the coincidence detector crystal. In this embodiment, image reconstruction is performed using scanning data from multiple layers of the coincidence detector crystal. By comparing the reconstruction effect of the scanned object in different reconstructed images, the starting depth of the coincidence response line is adjusted. By aligning the reconstruction effects between different reconstructed images, the DOI readout depth of each layer of the coincidence detector crystal can be indirectly calibrated in the integrated PET system without relying on a high-quality radiation source, effectively improving the operability of the detector crystal calibration.

[0107] In one embodiment, determining the reconstruction effect of the scanned object in the reconstructed image in step S102 may include the following steps:

[0108] Determine the location of the scanned object in the reconstructed image, and determine the reconstruction effect of the scanned object based on its location; and / or, determine the size of the scanned object in the reconstructed image, and determine the reconstruction effect of the scanned object based on its size.

[0109] In practice, by analyzing the reconstructed image, the location of the scanned object in the reconstructed image can be identified. For example, the center of the field of view of the PET system or other preset rotation center can be used as a reference. Based on the position of the scanned object relative to the center of the field of view or other preset rotation center, the location of the scanned object in the reconstructed image can be determined. Then, the reconstruction effect of the reconstructed image can be determined based on the location of the scanned object.

[0110] Of course, the size of the scanned object in the reconstructed image can also be determined. Specifically, the scanned object can have a certain size. In some embodiments, by scanning the object and analyzing the reconstructed image, a clear and distinct boundary of the scanned object can be identified in the reconstructed image, and then the size of the scanned object in the reconstructed image can be determined using this boundary. Since the reconstructed object size will deviate from the actual situation when the DOI readout depth of the detector crystal is inaccurate, the reconstruction effect of the reconstructed image can be determined based on the size of the scanned object.

[0111] In this embodiment, at least one of the location and size of the scanned object can be identified in the reconstructed image. By determining the location and / or size of the scanned object, the differences in the reconstruction effect of the scanned object in different reconstructed images can be accurately quantified, providing a reliable data basis for subsequent adjustment of the starting position of the conformal response line and matching the reconstruction effects of different reconstructed images.

[0112] In one embodiment, step S101, which involves scanning a target located within the field of view to obtain scanning data corresponding to the scanned object received by the detector crystal, may include the following steps:

[0113] When a scanning object located off-center within the field of view rotates around a preset rotation center, the scanning object is scanned to obtain scanning data that matches the detector crystal.

[0114] In practical applications, a scanning object can be positioned off-center within the field of view. This object can rotate around a preset rotation center within the field of view at this circumferentially off-center location. The PET system can then scan this rotating object. During scanning, the object is in a rotating state, allowing the coincidence detector crystal to receive the corresponding scan data. For example, as... Figure 2 As shown, when the scanned object rotates around a preset rotation center, it will move from position B to position C, and the coincidence detector crystals above and below it, as well as the corresponding coincidence response lines, will change. Furthermore, it should be noted that for a coincidence detector crystal at a single position, there can be multiple detector crystals coinciding, resulting in multiple coincidence response lines.

[0115] Accordingly, the image reconstruction based on the scan data received by this layer in step S102 may include:

[0116] The image is reconstructed based on the scan data received by each coincidence detector crystal in that layer.

[0117] Since the scanned object rotates around the preset rotation center during the scanning process, the same layer of different coincidence detector crystals can also be understood as being distributed around the preset rotation center. The scan data they acquire are related. Therefore, in this step, for the Nth (N is a positive integer) layer of different coincidence detector crystals, image reconstruction can be performed based on the scan data received by each coincidence detector crystal in that layer to obtain a reconstructed image describing the process of the scanned object rotating around the preset rotation center.

[0118] In this embodiment, the scanned object can be rotated around a preset rotation center, and image reconstruction can be performed based on the scan data of each coincidence detector crystal on the same layer to obtain a reconstructed image. By rotating the scanned object, the scan data related to different positions can be combined for reconstruction. Considering the average effect of the entire system, the reconstruction effect of the scanned object at different positions in the entire system can be comprehensively characterized, thereby improving the accuracy of subsequent DOI readout depth calibration.

[0119] In one embodiment, when the reconstruction effect includes the location of the scanned object determined based on the reconstructed image, such as Figure 4 As shown, determining the reconstruction effect of the scanned object in the reconstructed image in step S102 may include the following steps:

[0120] S401, based on the intensity of each pixel in the reconstructed image and the distance between each pixel and the preset rotation center, determine the distance between the scanned object carrying the radioactive tracer and the preset rotation center; the intensity of the pixel is positively correlated with the concentration of the radioactive tracer.

[0121] Specifically, the scanned object carries a radioactive tracer. The reconstructed image obtained from the scanned object can contain information representing the intensity of the corresponding location for each pixel. The intensity of the pixel is positively correlated with the concentration of the radioactive tracer at the corresponding location. That is, the higher the concentration of the radioactive tracer at a certain location, the higher the intensity of the pixel in the reconstructed image at that location.

[0122] Since only the scanned object carries the radioactive tracer within the field of view, after obtaining the reconstructed image, the pixels associated with the scanned object can be determined by comparing the intensity of each pixel. At the same time, the distance between the pixels associated with the scanned object and the preset rotation center can be determined based on the distance between each pixel and the preset rotation center, thereby determining the distance between the scanned object and the preset rotation center in the reconstructed image.

[0123] S402, determine the position of the scanned object in the reconstructed image based on the distance between the scanned object and the preset rotation center, and determine the reconstruction effect based on the position of the scanned object.

[0124] Once the distance between the scanned object and the preset rotation center is obtained, the position of the scanned object in the reconstructed image can be determined using the preset rotation center as a reference. For example, if the scanned object is located at a circumferential offset at a distance of x millimeters from the preset rotation center in the reconstructed image, and since the scanned object is currently rotating around the preset rotation center, the rotation radius of the scanned object within the field of view can also be determined based on the distance between the scanned object and the preset rotation center. Then, the reconstruction effect of the scanned object can be obtained based on its position.

[0125] In this embodiment, the location of the scanned object in the reconstructed image can be accurately identified based on the intensity of each pixel in the reconstructed image and the distance of each pixel from the preset rotation center, thereby determining a quantifiable and comparable reconstruction effect.

[0126] In one embodiment, step S401, determining the distance between the scanned object carrying the radioactive tracer and the preset rotation center based on the intensity of each pixel in the reconstructed image and the distance of each pixel from the preset rotation center, may include:

[0127] Using pixel intensity as the ordinate and the distance between a pixel and a preset rotation center as the abscissa, a scatter plot is generated based on the intensity of each pixel in the reconstructed image and the distance between each pixel and the preset rotation center. Curve fitting is performed on the scatter plot, and the mapping relationship between the distance between a pixel and the preset rotation center and the pixel intensity is determined based on the curve fitting results. The distance between the pixel and the preset rotation center when the intensity is at its strongest is determined based on the mapping relationship and is used as the distance between the scanning object and the preset rotation center.

[0128] In practical applications, after obtaining the reconstructed image, the intensity of each pixel in the reconstructed image and the distance between each pixel and the preset rotation center can be determined. Then, a scatter plot is generated by combining the intensity of each pixel in the reconstructed image with the distance between each pixel and the preset rotation center as the x-axis. In other words, after obtaining the reconstructed image, each point in the reconstructed image is mapped to this coordinate system with the intensity as the y-axis and the distance between each pixel and the preset rotation center as the x-axis, resulting in a scatter plot containing multiple points. Each point in the scatter plot corresponds to a pixel in the reconstructed image.

[0129] Furthermore, curve fitting can be performed on the scatter plot. Based on the curve fitting results, the distance between each pixel and the preset rotation center, the pixel intensity, and the mapping relationship between the two can be determined. For example, for a scatter plot... Figure 5aThe reconstructed image shown is obtained by scanning an object that rotates around a preset rotation center at a circumferential eccentricity. It is a circle with a radius of approximately 136 mm. The intensity (unit: au, or Absorbance Unit) of each pixel in the reconstructed image and the distance s (unit: millimeters) between each pixel and the center of the circle (corresponding to the preset rotation center) are plotted as follows: Figure 5b The scatter plot shown is then used to fit the points on the scatter plot to a curve, and the mapping relationship between the distance and intensity of the pixel and the preset rotation center is obtained based on the fitting result.

[0130] In some examples, scatter plots and curve fitting are performed separately for each reconstructed image, and the position of the scanned object in each reconstructed image is determined based on the curve fitting results. In other examples, pixel information from multiple reconstructed images can be plotted in the same scatter plot, and curve fitting can be performed on the individual points in this scatter plot for comprehensive analysis. For example, each pixel in each reconstructed image can be mapped to a coordinate system with intensity as the ordinate and the distance between the pixel and a preset rotation center as the abscissa. Then, the average intensity of multiple scatter points at the same distance s can be determined, and curve fitting can be performed based on the average value at each distance s. For example, the fitting result can be as follows: Figure 5b The fitted curve is shown in the figure. The fitting center of the fitted curve is located at 136.22 mm, and the full width at half maximum (FWHM) is 1.2.

[0131] After obtaining the curve fitting results, the mapping relationship between the distance and intensity of the pixel and the preset rotation center can be obtained. Since the pixel intensity is highest at the location of the scanned object, the distance between the pixel and the preset rotation center when the intensity is strongest can be determined based on this mapping relationship, and this distance can be used as the distance between the scanned object and the preset rotation center in the reconstructed image. Therefore, in this embodiment, the relative positional relationship between the scanned object and the preset rotation center can be accurately determined by combining the pixel intensity and its distance from the preset rotation center.

[0132] In one embodiment, step S103, adjusting the starting depth of the response line based on the reconstruction effects of the scanned object until the reconstruction effects of the scanned object match in each reconstructed image, may include the following steps:

[0133] In the multilayer of the coincidence detector crystal, a target layer is identified as a reference, and the reconstructed image corresponding to the target layer is used as a reference reconstructed image. For other layers in the coincidence detector crystal besides the target layer, if the reconstruction effect of the scanned object in the reconstructed image of that layer does not match the reconstruction effect in the reference reconstructed image, the starting depth of the corresponding coincidence response line is adjusted until the reconstruction effect matches.

[0134] In practical applications, when aligning the reconstruction effects of the scanned object in the corresponding reconstructed images of each layer, a target layer can be first determined as a baseline among the multiple layers of the detector crystal. The reconstructed image corresponding to the target layer is then used as the reference reconstructed image in the current reconstruction effect alignment process. The reference reconstructed image can be understood as a reference used when adjusting the reconstruction effect; the reconstruction effects of other reconstructed images can be adjusted towards the reconstruction effect of the reference reconstructed image. In some embodiments, the first layer in the detector crystal can be determined as the target crystal layer, so that the reconstructed images of subsequent layers are aligned with the reconstructed image of the first layer. Of course, other layers can also be selected as the target layer.

[0135] Then, for the other layers in the coincidence detector crystal—that is, each layer in the coincidence detector crystal other than the target layer—the reconstruction effect of the scanned object in the reconstructed image of that layer can be compared with the reconstruction effect of the reference reconstructed image. If the two reconstruction effects match, it can be determined that there is no need to adjust the starting depth of the coincidence response line of that layer for the time being; if the two reconstruction effects do not match, and the position or size of the scanned object in the reconstructed image of that layer is too large or too small, the starting depth of the coincidence response line of that layer can be adjusted until the reconstruction effect matches.

[0136] In this embodiment, by selecting the reconstructed image of the target layer as the reference reconstructed image, and adjusting the starting depth of the response line when the reconstruction effect of other layers does not match it, the reconstruction effect of different reconstructed images can be quickly aligned, and the DOI readout depth of each layer can be calibrated indirectly and quickly.

[0137] In some embodiments, after aligning the reconstruction results of each layer of the reconstructed image, it can be determined whether the reconstructed result after alignment meets the requirements. For example, whether the position or size of the scanned object in the reconstructed image obtained after alignment matches the actual position or size of the scanned object. If the difference is large, the DOI readout depth scale position of all layers can be shifted as a whole to quickly improve the accuracy of the DOI readout depth of each layer.

[0138] In other embodiments, the reconstruction effect of the reconstructed image can be aligned with the actual situation of the scanned object. For example, by adjusting the starting depth of the coincidence response line, the location and / or size of the scanned object in the reconstructed image can be aligned with the actual location and / or size of the scanned object in the real world. For instance, if the reconstruction effect is determined by the size of the scanned object in the reconstructed image, before adjusting the starting depth of the coincidence response line using the method of this application, the size of the scanned object in the reconstructed image may deviate from the actual situation due to the possibility of inaccurate DOI readout depth scale in the coincidence detector crystal. Furthermore, the size read from the reconstructed images of different layers may also differ. By adjusting the current starting depth of the coincidence response line and changing the readout depth information, the size of the scanned object in the reconstructed images of different layers can be aligned with the actual situation.

[0139] In one embodiment, such as Figure 6 As shown, a PET image acquisition method is provided. This embodiment illustrates the application of this method to a positron emission tomography (PET) system. In this embodiment, the method includes the following steps:

[0140] S601, the phantom located within the field of view is scanned to obtain the scan data corresponding to the phantom received by the coincidence detector crystal; at least one of the coincidence detector crystals is divided into multiple segments, each segment corresponding to different DOI information.

[0141] In practice, a phantom can be placed within the PET field of view. In some optional embodiments, the phantom can be a radioactive point source, which can be placed at a circumferential off-center position within the field of view; or, the phantom can be another object with a certain size (e.g., the phantom size is larger than a preset size threshold). For specific phantom placement methods, please refer to the description of the scanning object placement in the previous embodiments, which will not be repeated here.

[0142] In a PET system, multiple coincidence detector crystals can be set up. For some or all of the multiple coincidence detector crystals, each coincidence detector crystal can be divided into multiple segments. Multiple segments on the same coincidence detector crystal can correspond to different DOI information. In some examples, the DOI information of each segment can be information that characterizes the readout depth of that segment. For example, it can include at least one of the following: the specific DOI readout depth of that segment, the deviation of the DOI readout depth of that segment relative to the DOI readout depth of other segments, and the deviation level.

[0143] After setting up a phantom within the field of view, the phantom located within the field of view can be scanned to obtain the scan data corresponding to the phantom received by the coincidence detector crystal. Each segment on the coincidence detector crystal can acquire the corresponding scan data.

[0144] S602, for each segment of the detector crystal, acquires an image of the phantom based on the scan data received from that segment.

[0145] S603, based on the image of the phantom, corrects the DOI information corresponding to each segment.

[0146] In practical applications, each segment of the coincidence detector crystal can acquire a corresponding scan object. For each segment of the coincidence detector crystal, an image of the phantom can be acquired based on the scan data received by that segment, and the DOI information corresponding to each segment can be calibrated based on the images acquired by each segment. Specifically, for example, a corresponding reconstructed image can be generated for each segment based on the scan data received by each segment. This reconstructed image is also called the phantom image. Then, the DOI information corresponding to each segment can be calibrated by aligning the images of each phantom segment. The specific calibration process can be combined with the PET detector readout depth acquisition method mentioned in one or more of the previous embodiments to obtain the DOI readout depth of each segment of the coincidence detector crystal, and then the DOI information corresponding to each segment can be corrected based on the obtained DOI readout depth. The specific processing steps can be referred to above, and will not be repeated here.

[0147] S604, Reconstruct the data of the scanned object based on the corrected DOI information to obtain a PET image of the scanned object.

[0148] After obtaining the corrected DOI information and completing the calibration of the PET system, the PET system can be used to scan the object based on the corrected DOI information to obtain the data corresponding to the scanned object. Then, the image can be reconstructed by combining the corrected DOI information to obtain the PET image of the scanned object.

[0149] In the aforementioned PET image acquisition method, a phantom located within the field of view is scanned to obtain scan data corresponding to the phantom received by a coincidence detector crystal. At least one coincidence detector crystal is divided into multiple segments, each corresponding to a different DOI (Domain of Interest) information. Then, for each segment of the coincidence detector crystal, an image of the phantom can be acquired based on the scan data received by that segment. Based on the phantom image, the DOI information corresponding to each segment is corrected. Furthermore, the data of the scanned object can be reconstructed based on the corrected DOI information to acquire a PET image of the scanned object. In this embodiment, by acquiring an image of the phantom based on the scan data received by each segment of the coincidence detector crystal, correcting the DOI information corresponding to each segment, and then acquiring a PET image of the scanned object based on the corrected DOI information, accurate DOI information can be quickly acquired in an integrated PET system without relying on a high-quality radiation source. By reconstructing the scanned object data based on this DOI information, the PET image quality of the entire PET system can be effectively improved.

[0150] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0151] Based on the same inventive concept, this application also provides a detector crystal depth reading device for implementing the detector crystal depth reading method described above. The solution provided by this device is similar to the solution described in the above method; therefore, the specific limitations in one or more detector crystal depth reading device embodiments provided below can be found in the limitations of the detector crystal depth reading method described above, and will not be repeated here.

[0152] In one exemplary embodiment, such as Figure 7 As shown, a readout depth acquisition device for a PET detector is provided, applied to a positron emission tomography (PET) system. The device includes:

[0153] The scanning module 701 is used to scan the object located within the field of view and obtain the scanning data corresponding to the object received by the coincidence detector crystal; at least one of the coincidence detector crystals is divided into multiple layers, each layer corresponding to a DOI readout depth.

[0154] Image reconstruction module 702 is used to perform image reconstruction for each layer of the coincidence detector based on the scan data received by that layer, and to determine the reconstruction effect of the scanned object in the reconstructed image; the reconstruction effect is related to the starting depth of the coincidence response line of that layer.

[0155] The starting depth adjustment module 703 is used to adjust the starting depth of the response line based on the reconstruction effect of the scanned object until the reconstruction effect of the scanned object in each reconstruction image matches.

[0156] The calibration module 704 is used to obtain the DOI readout depth of each layer based on the current starting depth of the coincidence response line of each layer of the coincidence detector crystal.

[0157] In one embodiment, the scanning module 701 is used for:

[0158] When a scanning object located off-center within the field of view rotates around a preset rotation center, the scanning object is scanned to obtain scanning data corresponding to the scanning object received by the detector crystal.

[0159] The image reconstruction module 702 is used for:

[0160] The image is reconstructed based on the scan data received by each coincidence detector crystal in that layer.

[0161] In one embodiment, the image reconstruction module 702 is used for:

[0162] The distance between the scanned object carrying the radioactive tracer and the preset rotation center is determined based on the intensity of each pixel in the reconstructed image and the distance of each pixel from the preset rotation center; the intensity of the pixel is positively correlated with the concentration of the radioactive tracer.

[0163] The location of the scanned object in the reconstructed image is determined based on the distance between the scanned object and the preset rotation center, and the reconstruction effect is determined based on the location of the scanned object.

[0164] In one embodiment, the image reconstruction module 702 is used for:

[0165] A scatter plot is generated based on the intensity of each pixel in the reconstructed image and the distance between each pixel and the preset rotation center, with the pixel intensity as the ordinate and the distance between each pixel and the preset rotation center as the abscissa.

[0166] Curve fitting is performed on the scatter plot, and the mapping relationship between the distance between the pixel and the preset rotation center and the intensity of the pixel is determined based on the curve fitting result.

[0167] The distance between the pixel and the preset rotation center when the intensity is at its strongest is determined based on the mapping relationship, and is used as the distance between the scanned object and the preset rotation center.

[0168] In one embodiment, the image reconstruction module 702 is used for:

[0169] Determine the location of the scanned object in the reconstructed image, and determine the reconstruction effect of the scanned object based on its location;

[0170] And / or,

[0171] Determine the size of the scanned object in the reconstructed image, and determine the reconstruction effect of the scanned object based on the size of the scanned object.

[0172] In one embodiment, the starting depth adjustment module 703 is used for:

[0173] In the multilayer of the detector crystal, a target layer is identified as a reference, and the reconstructed image corresponding to the target layer is used as a reference reconstructed image.

[0174] For layers other than the target layer in the coincidence detector crystal, if the reconstruction effect of the scanned object in the reconstructed image of that layer does not match the reconstruction effect in the reference reconstructed image, the starting depth of the corresponding coincidence response line is adjusted until the reconstruction effect matches.

[0175] The various modules in the aforementioned PET detector's readout depth acquisition device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in hardware within or independently of the processor in a computer device, or stored in software within the computer device's memory, allowing the processor to call and execute the corresponding operations of each module.

[0176] In one exemplary embodiment, such as Figure 8 As shown, a PET image acquisition device is provided, the device comprising:

[0177] The scanning data acquisition module 801 is used to scan the phantom located within the field of view to obtain the scanning data corresponding to the phantom received by the coincidence detector crystal; at least one of the coincidence detector crystals is divided into multiple segments, each segment corresponding to different DOI information;

[0178] Image acquisition module 802 is used to acquire an image of the phantom for each segment of the coincidence detector crystal based on the scan data received for that segment;

[0179] Correction module 803 is used to correct the DOI information corresponding to each segment based on the image of the phantom;

[0180] The PET image acquisition module 804 is used to reconstruct the data of the scanned object based on the corrected DOI information and acquire the PET image of the scanned object.

[0181] Each module in the aforementioned PET image acquisition device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the operations corresponding to each module.

[0182] In one exemplary embodiment, a computer device is provided, which may be a terminal (such as a terminal within a PET system), and its internal structure diagram may be as follows. Figure 9 As shown, the computer device includes a processor, memory, input / output interface, communication interface, display unit, and input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interface. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The input / output interface is used for exchanging information between the processor and external devices. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, NFC (Near Field Communication), or other technologies. When executed by the processor, the computer program implements a method for obtaining the readout depth of a PET detector or a method for acquiring PET images. The display unit is used to form a visually visible image and can be a display screen, a projection device, or a virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the computer device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads set on the casing of the computer device, or external keyboards, touchpads, or mice, etc.

[0183] Those skilled in the art will understand that Figure 9 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0184] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0185] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps in the above method embodiments.

[0186] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above method embodiments.

[0187] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0188] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0189] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0190] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for obtaining the readout depth of a PET detector, characterized in that, The method, applied to a positron emission tomography (PET) system, includes: The scanning object located within the field of view is scanned to obtain scanning data corresponding to the scanning object received by the coincidence detector crystal; at least one of the coincidence detector crystals is divided into multiple layers, each layer corresponding to a DOI readout depth; the scanning object is set at the circumferential offset within the field of view, and / or, at least a portion of the scanning object is located at the circumferential offset within the field of view; For each layer of the coincidence detector crystal, image reconstruction is performed based on the scan data received by that layer, and the reconstruction effect of the scanned object in the reconstructed image is determined; the reconstruction effect is related to the starting depth of the coincidence response line of that layer. Based on the reconstruction results of the scanned object, the starting depth of the response line is adjusted until the reconstruction results of the scanned object in each reconstructed image match. The DOI readout depth of each layer is obtained based on the current starting depth of the coincidence response line of each layer of the coincidence detector crystal.

2. The method according to claim 1, characterized in that, The step of scanning the object located within the field of view to obtain scanning data corresponding to the scanned object that matches the detector crystal includes: When a scanning object located off-center within the field of view rotates around a preset rotation center, the scanning object is scanned to obtain scanning data corresponding to the scanning object received by the detector crystal. The image reconstruction based on the scan data received by this layer includes: The image is reconstructed based on the scan data received by each coincidence detector crystal in that layer.

3. The method according to claim 2, characterized in that, Determining the reconstruction effect of the scanned object in the reconstructed image includes: The distance between the scanned object carrying the radioactive tracer and the preset rotation center is determined based on the intensity of each pixel in the reconstructed image and the distance of each pixel from the preset rotation center; the intensity of the pixel is positively correlated with the concentration of the radioactive tracer. The location of the scanned object in the reconstructed image is determined based on the distance between the scanned object and the preset rotation center, and the reconstruction effect is determined based on the location of the scanned object.

4. The method according to claim 3, characterized in that, Determining the distance between the scanned object carrying the radioactive tracer and the preset rotation center based on the intensity of each pixel in the reconstructed image and the distance of each pixel to the preset rotation center includes: A scatter plot is generated based on the intensity of each pixel in the reconstructed image and the distance between each pixel and the preset rotation center, with the pixel intensity as the ordinate and the distance between each pixel and the preset rotation center as the abscissa. Curve fitting is performed on the scatter plot, and the mapping relationship between the distance between the pixel and the preset rotation center and the intensity of the pixel is determined based on the curve fitting result. The distance between the pixel and the preset rotation center when the intensity is at its strongest is determined based on the mapping relationship, and is used as the distance between the scanned object and the preset rotation center.

5. The method according to claim 1, characterized in that, Determining the reconstruction effect of the scanned object in the reconstructed image includes: Determine the location of the scanned object in the reconstructed image, and determine the reconstruction effect of the scanned object based on its location; And / or, Determine the size of the scanned object in the reconstructed image, and determine the reconstruction effect of the scanned object based on the size of the scanned object.

6. The method according to any one of claims 1 to 5, characterized in that, The step of adjusting the starting depth of the response line based on the reconstruction results of the scanned object until the reconstruction results of the scanned object in each reconstructed image match includes: In the multilayer of the detector crystal, a target layer is identified as a reference, and the reconstructed image corresponding to the target layer is used as a reference reconstructed image. For layers other than the target layer in the coincidence detector crystal, if the reconstruction effect of the scanned object in the reconstructed image of that layer does not match the reconstruction effect in the reference reconstructed image, the starting depth of the corresponding coincidence response line is adjusted until the reconstruction effect matches.

7. A method for acquiring PET images, characterized in that, The method includes: The phantom located within the field of view is scanned to obtain scan data corresponding to the phantom received by the coincidence detector crystal; at least one of the coincidence detector crystals is divided into multiple segments, each segment corresponding to different DOI information; For each segment of the coincident detector crystal, an image of the phantom is obtained based on the scan data received from that segment; Based on the image of the phantom and the readout depth acquisition method of the PET detector as described in any one of claims 1 to 6, the DOI information corresponding to each segment is obtained; Based on the DOI information, the data of the scanned object is reconstructed to obtain a PET image of the scanned object.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the PET detector readout depth acquisition method according to any one of claims 1 to 6 or the PET image acquisition method according to claim 7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the PET detector readout depth acquisition method according to any one of claims 1 to 6 or the PET image acquisition method according to claim 7.

10. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the steps of the readout depth acquisition method of the PET detector according to any one of claims 1 to 6 or the PET image acquisition method according to claim 7.

Images