Time correction method and device, computer storage medium and digital PET system

Abstract

The invention discloses a time correction method and device, a computer storage medium and a digital PET system. The time correction method comprises the following steps: step S100, carrying out in-ring time correction on crystal strips of a plurality of detection rings in sequence to obtain in-ring time correction values of all the crystal strips; s200, all coincidence events between every two adjacent detection rings are obtained in sequence, and the single event arrival time of each coincidence event on the crystal strip is obtained; and S300, carrying out inter-ring time correction on the plurality of detection rings according to the position of the current to-be-calibrated ring, the in-ring time correction value and the peak value of the difference value of the arrival time of the two single events of each coincidence event. According to the invention, the overall time correction quality of the digital PET system can be improved, the image quality can be improved, the radiation dose can be reduced, and the inter-ring time correction of the long-axis PET can be realized at the cost as low as possible.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of data processing, in particular to a time correction method and device for long-axis PET, a computer storage medium, a computer program product and a digital PET system. BACKGROUND

[0002] Positron Emission Tomography (PET) is one of the most advanced molecular imaging technologies at present, which reconstructs images by detecting coincidence events corresponding to annihilation of positive and negative electrons in the object to be measured.

[0003] With the continuous expansion of detection requirements, higher requirements are put forward for the axial length of PET. In order to make the axial detection length of the PET detection system longer, multiple detection rings are usually arranged in the axial direction to achieve this, each detection ring including a plurality of detectors, and each detector including a plurality of crystal bars. The differences in different detector hardware, such as optical propagation bias, circuit propagation bias, reference clock skew, etc., result in a time difference between the time when the gamma photon hits the detector and the time when the actual pulse signal is obtained. In order to obtain as many coincidence events as possible, the time difference caused by hardware differences needs to be corrected to the same level to achieve intra-ring time correction. However, the clock line synchronization accuracy of the clock board of the detector of different detection rings is inconsistent, and on the basis of the original hardware differences, there is an additional time difference between the data of different detection rings, which needs to be corrected.

[0004] Generally speaking, on a single ring PET, a line source can be used as the basis for data acquisition during time correction. However, the length of the line source is shorter than the axial length of the PET, making it difficult to match the axial length of the PET, and the cost of customizing the length of the line source is high. Therefore, under the consideration of cost, it is difficult to perform inter-ring time correction. If inter-ring time correction is not performed, a large number of inter-ring coincidence events of different rings will be lost, which will affect the system sensitivity and imaging effect. SUMMARY

[0005] Therefore, it is necessary to provide a time correction method, device, computer storage medium, computer program product and digital PET system to solve at least one technical problem existing in the traditional scheme.

[0006] According to a first aspect of the present application, a time correction method is provided, comprising: step S100, sequentially performing intra-ring time correction on crystal bars of a plurality of detection rings to obtain intra-ring time correction values of all the crystal bars; step S200, sequentially obtaining all coincidence events between every two adjacent detection rings and obtaining single event arrival times of each coincidence event on the crystal bars; and step S300, performing inter-ring time correction on the plurality of detection rings according to a position of a current ring to be calibrated, the intra-ring time correction values and a peak value of a difference between two single event arrival times of each coincidence event.

[0007] According to an embodiment of the present application, step S200 comprises: sequentially obtaining all coincidence events between every two adjacent detection rings, selecting one of the two adjacent detection rings as a reference ring and the other as a ring to be calibrated, and for each coincidence event, obtaining a first arrival time on a crystal bar of the reference ring and a second arrival time on a crystal bar of the ring to be calibrated. Step S300 comprises: obtaining an inter-ring time correction value of each crystal bar of the ring to be calibrated according to a positional relationship between the current ring to be calibrated and a first reference ring, the intra-ring time correction value of each crystal bar on the current ring to be calibrated, and a peak value of a difference between the first arrival time and the second arrival time of all coincidence events on the current ring to be calibrated.

[0008] According to an embodiment of the present application, if the current ring to be calibrated is adjacent to the first reference ring, step S300 comprises: obtaining a peak value of a difference between the first arrival time and the second arrival time of all coincidence events on the current ring to be calibrated, and adding the peak value to the intra-ring time correction value of all the crystal bars of the ring to be calibrated to obtain the inter-ring time correction value.

[0009] According to an embodiment of the present application, if the current ring to be calibrated is separated from the first reference ring by one or more other detection rings, step S300 comprises: obtaining a peak value of a difference between the first arrival time and the second arrival time of all coincidence events of the one or more other detection rings, and obtaining a peak value of a difference between the first arrival time and the second arrival time of a coincidence event corresponding to a current crystal bar to be deposited; adding all the peak values to the intra-ring time correction value of all the crystal bars of the current ring to be calibrated to obtain the inter-ring time correction value of each crystal bar.

[0010] According to an embodiment of the present application, step S200 comprises: sequentially obtaining all coincidence events between every two adjacent detection rings, selecting one of the two adjacent detection rings as a reference ring and the other as a ring to be calibrated, and for each coincidence event, obtaining a first arrival time on a crystal bar of the reference ring and a second arrival time on a crystal bar of the ring to be calibrated. The step S300 comprises: obtaining the inter-ring time correction value of each crystal strip of the current to-be-corrected ring according to the positional relationship between the current to-be-corrected ring and the first reference ring, the intra-ring time correction value of each crystal strip on the current to-be-corrected ring, and the peak value of the difference between the first arrival time and the second arrival time of all coincidence events on the current to-be-corrected ring minus the photon flight time.

[0011] According to one embodiment of the present application, if the current to-be-corrected ring is adjacent to the first reference ring, the step S300 comprises: obtaining the peak value of the difference between the first arrival time and the second arrival time of all coincidence events on the current to-be-corrected ring minus the photon flight time, and adding the peak value to the intra-ring time correction value of all crystal strips of the to-be-corrected ring to obtain the inter-ring time correction value.

[0012] According to one embodiment of the present application, if the current to-be-corrected ring is separated from the first reference ring by one or more other detection rings, the step S300 comprises: obtaining the peak value of the difference between the first arrival time and the second arrival time of all coincidence events on the one or more other detection rings minus the photon flight time, and obtaining the peak value of the difference between the first arrival time and the second arrival time of the coincidence events corresponding to the current to-be-corrected crystal strip deposition minus the photon flight time; adding all the peak values to the intra-ring time correction value of all crystal strips of the current to-be-corrected ring to obtain the inter-ring time correction value of each crystal strip.

[0013] According to one embodiment of the present application, the inter-ring time correction is performed with the first detection ring as the reference ring and the second detection ring as the to-be-corrected ring, and then the inter-ring time correction is performed with the previous detection ring as the reference ring and the subsequent detection ring as the to-be-corrected ring in sequence.

[0014] According to one embodiment of the present application, the inter-ring time correction is performed with any detection ring as the reference ring and the detection ring adjacent to one side / two sides of the reference ring as the to-be-corrected ring, and when there is an uncorrected detection ring on one side or both sides of the corrected detection ring, the inter-ring time correction is performed with the corrected detection ring as the reference ring and the uncorrected detection ring as the to-be-corrected ring.

[0015] According to one embodiment of the present application, the step S200 comprises: screening the coincidence events to remove the response lines with both ends in the same detection ring and the response lines not passing through the source, and obtaining the single-event arrival time of the remaining coincidence events on the crystal strip.

[0016] According to one embodiment of the present application, the steps S100 and S200 are both performed by data acquisition on the line source detection to calculate the intra-ring time correction value and obtain the single-event arrival time.

[0017] According to one embodiment of the present application, in step S100, the line source is placed in the detection field of each detection ring in turn; and in step S200, the line source is placed between every two adjacent detection rings, and the two ends of the line source are respectively located in the partial detection field of two detection rings.

[0018] According to one embodiment of the present application, the arrangement direction of the line source is parallel to the axial direction of the detection ring.

[0019] According to one embodiment of the present application, the arrangement direction of the line source is coincident with the axial direction of the detection ring.

[0020] According to a second aspect of the present application, a time correction device is provided, comprising: a ring-in correction module configured to sequentially perform ring-in time correction on the crystal bars of a plurality of detection rings to obtain ring-in time correction values of all the crystal bars; a data acquisition module configured to sequentially acquire all coincidence events between every two adjacent detection rings, and acquire single event arrival times of each coincidence event on the crystal bars; and a ring-to-ring correction module configured to perform ring-to-ring time correction on a plurality of detection rings according to the position of a current ring to be calibrated, the ring-in time correction values, and the peak value of the difference between two single event arrival times of each coincidence event.

[0021] According to one embodiment of the present application, the data acquisition module is configured to: sequentially acquire all coincidence events between every two adjacent detection rings, select one of the two adjacent detection rings as a reference ring and the other as a ring to be calibrated, and for each coincidence event, acquire a first arrival time on the crystal bars of the reference ring and a second arrival time on the crystal bars of the ring to be calibrated. The ring-to-ring correction module is configured to: according to the positional relationship between the current ring to be calibrated and the first reference ring, the ring-in time correction value of each crystal bar on the current ring to be calibrated, and the peak value of the difference between the first arrival time and the second arrival time of all coincidence events on the current ring to be calibrated, obtain the ring-to-ring time correction value of each crystal bar of the ring to be calibrated.

[0022] According to one embodiment of the present application, if the current ring to be calibrated is adjacent to the first reference ring, the ring-to-ring correction module is configured to: acquire the peak value of the difference between the first arrival time and the second arrival time of all coincidence events on the current ring to be calibrated, and add the peak value to the ring-in time correction value of all crystal bars of the ring to be calibrated to obtain the ring-to-ring time correction value.

[0023] According to one embodiment of the present application, if the current ring to be calibrated is separated from the first reference ring by one or more other detection rings, the ring-to-ring correction module is configured to: obtaining the peak value of the difference between the first arrival time and the second arrival time of all coincidence events of the one or more other detection rings, and obtaining the peak value of the difference between the first arrival time and the second arrival time corresponding to the coincidence events of the current crystal strip to be corrected; adding all the peak values to the intra-ring time correction values of all crystal strips of the current ring to be corrected to obtain the inter-ring time correction values of the crystal strips.

[0024] According to one embodiment of the present application, the data acquisition module is configured to: sequentially obtain all coincidence events between every two adjacent detection rings, select one of the every two adjacent detection rings as a reference ring and the other as a ring to be corrected, and for each coincidence event, obtain the first arrival time on the crystal strip of the reference ring and the second arrival time on the crystal strip of the ring to be corrected. The inter-ring correction module is configured to: according to the positional relationship between the current ring to be corrected and the first reference ring, the intra-ring time correction value of each crystal strip on the current ring to be corrected, and the peak value of the difference between the first arrival time and the second arrival time of all coincidence events on the current ring to be corrected minus the photon flight time, obtain the inter-ring time correction value of each crystal strip of the ring to be corrected.

[0025] According to one embodiment of the present application, if the current ring to be corrected is adjacent to the first reference ring, the inter-ring correction module is configured to: obtain the peak value of the difference between the first arrival time and the second arrival time of all coincidence events on the current ring to be corrected minus the photon flight time, and add the peak value to the intra-ring time correction values of all crystal strips of the ring to be corrected to obtain the inter-ring time correction values.

[0026] According to one embodiment of the present application, if the current ring to be corrected is separated from the first reference ring by one or more other detection rings, the inter-ring correction module is configured to: obtain the peak value of the difference between the first arrival time and the second arrival time of all coincidence events of the one or more other detection rings minus the photon flight time, and obtain the peak value of the difference between the first arrival time and the second arrival time corresponding to the coincidence events of the current crystal strip to be corrected minus the photon flight time; add all the peak values to the intra-ring time correction values of all crystal strips of the current ring to be corrected to obtain the inter-ring time correction values of the crystal strips.

[0027] According to one embodiment of the present application, the data acquisition module is configured to: screen the coincidence events, eliminate the response lines with both ends in the same detection ring and the response lines not passing through the source in the response lines corresponding to the coincidence events, and obtain the single-event arrival time of the remaining coincidence events on the crystal strips.

[0028] According to a third aspect of the present application, a computer storage medium is provided, which stores a computer program, and the computer program is executed by a processor to implement the steps of the time correction method.

[0029] According to a fourth aspect of the present application, a computer program product is provided, which comprises a computer program or instructions, and the computer program or instructions are executed by a processor to implement the steps of the time correction method.

[0030] According to a fifth aspect of the present application, a digital PET system is provided, which adopts the time correction device to perform time correction.

[0031] The time correction method, device, computer storage medium, computer program product and digital PET system provided by the present application first perform intra-ring time correction, and then perform inter-ring time correction on each detection ring by acquiring single event arrival time of inter-ring coincidence events and combining the single event arrival time and the intra-ring time correction value. Since the length of the existing line source can basically cover a single detection ring, the length of the line source provides a basis for acquisition of inter-ring coincidence events, and by combining the inter-ring coincidence event information, the inter-ring time correction is not limited to the length of the line source, so that the quality of the overall time correction of the digital PET system can be improved, the image quality can be improved, the radiation dose can be reduced, and the inter-ring time correction of the long-axis PET can be realized at the lowest possible cost. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0033] Figure 1 A flowchart of the time correction method in one of the embodiments of the present application; Figure 2 A structure side view of the long-axis PET in one of the embodiments of the present application; Figure 3 An axial sectional view of intra-ring time correction of the long-axis PET in one of the embodiments of the present application; Figure 4 An axial sectional view of inter-ring time correction of the long-axis PET in one of the embodiments of the present application; Figure 5 A schematic view of the line source located at the axial center of the long-axis PET in one of the embodiments of the present application; Figure 6A histogram of the first difference value in one embodiment of the present application; Figure 7 A structure diagram of a time correction device in one embodiment of the present application; Figure 8 A structure diagram of a time correction system in one embodiment of the present application; Figure 9 An internal structure diagram of a computer device in one embodiment of the present application. DETAILED DESCRIPTION

[0034] In order to make the above objectives, features and advantages of the present application more obvious and comprehensible, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, a lot of specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be implemented in many different ways other than those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0035] It should be noted that when an element is referred to as being "fixed" to another element, it can be directly fixed to the other element or there can be an intermediate element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or there can be an intermediate element. The terms "substantially equal" or "substantially equivalent" as used herein mean that the difference between them is within an error range considered equivalent in the art. The terms "vertical", "horizontal", "left", "right" and the like used herein are for illustrative purposes only.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" or "and / or" used herein includes any and all combinations of one or more related listed items.

[0037] In view of the technical problems existing in the prior art, the present application proposes a method, device and supporting application which can at least perform intra- and inter-ring time correction on long-axis PET.

[0038] In some embodiments, the time correction method can be performed by a time correction device. For example, the time correction method can be partially or entirely stored in a storage device (such as a self-provided storage module of the detection device or an external storage device) in the form of programs or instructions, which can implement the time correction method when executed. The time correction device provided in the present application for implementing the above-mentioned time correction method can be a device with a large amount of computing resources (for example, a computer, a server, cloud computing, etc.), or a device with limited computing resources (for example, an FPGA (Field Programmable Gate Array) chip board, an ASIC (Application-Specific Integrated Circuit) chip board, etc. hardware circuit).

[0039] Some preferred embodiments of the present application are described below with reference to the accompanying drawings. It should be noted that the following description is for the purpose of illustration and is not intended to limit the scope of protection of the present application.

[0040] Figure 1 For the flowchart of the time correction method in one embodiment of the present application, in one embodiment, the time correction method can include the following steps S100-S300.

[0041] Step S100: sequentially performing in-ring time correction on the crystal bars of the plurality of detection rings to obtain in-ring time correction values of all the crystal bars.

[0042] Exemplarily, Table 1 below shows an in-ring time correction value table of part of the crystal bars of a long-axis PET.

[0043] Table 1 It can be understood that in actual correction, a long-axis PET will have several in-ring time correction values. Taking the crystal bar with the detector IP of 1 and the position number of 0 as the reference, the in-ring time correction value of the crystal bar is 0, and the in-ring correction values of other crystal bars are the values in the table with 0 as the reference. When performing in-ring time correction, the in-ring time correction value is directly used for time correction.

[0044] In the present application, the method and device provided in the present application can be applied to a long-axis PET, which includes a plurality of detection rings arranged coaxially. Exemplarily, taking a long-axis PET including two detection rings as an example, and taking another long-axis PET including four detection rings 100 (see Figure 2). Each detection ring includes 12 or 24 or 48 detectors, each detector includes an 8x8 crystal bar array, or a 12x12 crystal bar array, of course, each detector also includes photoelectric devices and circuits. Of course, those skilled in the art can understand that the number of the above-mentioned detection rings, the number of the detectors, and the number of the crystal bars can be expanded.

[0045] Specifically, in one example of the present application, referring to Figure 3 , by placing the line source 200 in the field of view of each detection ring 100 in turn to collect data, the time of each crystal bar is corrected according to the collected data, and the intra-ring time correction value of each crystal bar is obtained. It should be particularly pointed out that due to the limitation of hardware, the intra-ring time correction values of each crystal bar are generally not exactly the same.

[0046] Preferably, the line source is arranged parallel to the axial direction of the detection ring, and more preferably, the line source is arranged coinciding with the axial direction of the detection ring.

[0047] Preferably, the length of the line source is substantially the same as the axial length of a single detection ring, or slightly larger than the axial length of a single detection ring, for example, substantially the same as the sum of the length of a single detection ring and the length of the gap on both sides thereof.

[0048] Optionally, the intra-ring time correction of each detection ring can be performed by using the existing time correction method, for example, according to the method described in CN202211731787.X, of course, those skilled in the art can understand that other methods capable of realizing intra-ring time correction in the prior art can also be used.

[0049] Step S200: sequentially obtaining all coincidence events between two adjacent detection rings, and obtaining the single event arrival time of each coincidence event on the crystal bar.

[0050] Taking the above-mentioned line source as an example for data collection, when obtaining all coincidence events between two adjacent detection rings, the line source 200 is placed between two adjacent detection rings 100 (see Figure 4 ), and the two ends of the line source 200 are required to enter the detection field of view of the two detection rings 100 respectively, so as to ensure that sufficient data is collected. Preferably, the length of the line source in the field of view of the two detection rings is the same.

[0051] The sequentially obtaining all coincidence events between every two adjacent detection rings can be sequentially obtained according to the arrangement order of the detection rings, or can be sequentially obtained according to user preference, or around the selected first reference ring. Generally, the selected first reference ring has the best performance. Illustratively, when sequentially obtaining according to the arrangement order of the detection rings, sequentially obtaining all coincidence events between every two adjacent detection rings means sequentially obtaining all first coincidence events between the first and second detection rings, all second coincidence events between the second and third detection rings, and all N-1 coincidence events between the N-1 and N detection rings. All first coincidence events form a data packet, all second coincidence events also form a data packet, and other coincidence events are the same. Each data packet is processed separately.

[0052] Preferably, in order to reduce the amount of data and optimize the data processing speed, in an example of the present application, the step S200 comprises: The coincidence events are screened, and coincidence events corresponding to response lines with both ends in the same detection ring and response lines not passing through the source are removed, and the single event arrival time of the remaining coincidence events on the crystal strip is obtained.

[0053] Since the purpose of the step S200 is to collect data for inter-ring event coincidence, only coincidence events occurring between rings are needed. On the response line, this means that the two ends of the response line are on two different detection rings. In addition, events not passing through the source are generally considered invalid events and are also removed.

[0054] Step S300: Inter-ring time correction is performed on a plurality of detection rings according to the inter-ring time correction value and the single event arrival time.

[0055] Specifically, in the present application, there are multiple ways to correct the inter-ring time. Different ways are used for correction according to whether the axial line of the line source coincides with the axis of the long-axis PET. According to different correction standards, for example, all detectors in each detection ring share a correction value after correction, or all crystal strips in each detector share a correction value after correction, or a single crystal strip uses a single correction value, different methods are used for correction. According to the positional relationship between the ring to be corrected and the first reference ring, different ways are used for correction.

[0056] Exemplarily, in one example of the present application, the axis of the line source coincides with the long-axis PET axis, and the same correction data is used for the same detection ring. Step S200 comprises: sequentially obtaining all coincidence events between every two adjacent detection rings, selecting one of the two adjacent detection rings as a reference ring and the other as a to-be-corrected ring, and for each coincidence event, obtaining a first arrival time on a crystal bar of the reference ring and a second arrival time on a crystal bar of the to-be-corrected ring. Step S300 comprises: according to the positional relationship between the current to-be-corrected ring and the first reference ring, the inter-ring time correction value of each crystal bar on the current to-be-corrected ring, and the peak value of the difference between the first arrival time and the second arrival time of all coincidence events on the current to-be-corrected ring, obtaining the inter-ring time correction value of each crystal bar of the to-be-corrected ring.

[0057] Specifically, if the current to-be-corrected ring is adjacent to the first reference ring, step S300 comprises: obtaining the peak value of the difference between the first arrival time and the second arrival time of all coincidence events on the current to-be-corrected ring, and adding the peak value to the intra-ring time correction value of all crystal bars of the to-be-corrected ring to obtain the inter-ring time correction value.

[0058] Specifically, if the current to-be-corrected ring is separated from the first reference ring by one or more other detection rings, step S300 comprises: obtaining the peak value of the difference between the first arrival time and the second arrival time of all coincidence events of the one or more other detection rings, and obtaining the peak value of the difference between the first arrival time and the second arrival time corresponding to the coincidence events deposited on the current to-be-corrected crystal bar; and adding all peak values to the intra-ring time correction value of all crystal bars of the current to-be-corrected ring to obtain the inter-ring time correction value of each crystal bar.

[0059] As a specific example of the above example, the first detection ring is taken as the first reference ring, the second detection ring is taken as the to-be-corrected ring, the line source is placed between the first detection ring and the second detection ring, and the response lines on the first detection ring and the second detection ring are obtained. For each response line, the first arrival time and the second arrival time are obtained, the first arrival time is subtracted from the second arrival time to obtain a first difference, the first difference corresponding to all response lines is obtained, the first peak value of all first differences is taken, the first peak value can be obtained by histogramming all first differences (the histogram is as shown in FIG. 3B), and the first peak value is the calibration data of the current to-be-corrected ring. The first peak value is as shown in FIG. 3C. Figure 6 Figure 6 ​The highest point of the middle curve, i.e., X = 8.66, can be understood that the value is only an example, the inter-ring time correction value of each crystal bar is obtained by adding the first peak value to the intra-ring time correction value of the corresponding crystal bar on the second detection ring; the second correction takes the second detection ring as the reference ring and the third detection ring as the to-be-calibrated ring, the line source is placed between the second detection ring and the third detection ring, the response lines on the second detection ring and the third detection ring at both ends are obtained, for each response line, the first arrival time and the second arrival time are obtained, the second difference value is obtained by subtracting the second arrival time from the first arrival time, the second difference values corresponding to all response lines are obtained, the second peak value of all second difference values is taken, the first peak value and the second peak value are added to the intra-ring time correction values of all crystal bars of the third detection ring to obtain the inter-ring time correction values of each crystal bar, and the same operation is performed on all crystal bars of all to-be-calibrated rings to perform inter-ring time correction on all crystal bars. Wherein, for different detection rings, the weights of different difference values can be the same or different.

[0060] Exemplarily, in one example of the present application, the axial direction of the line source is not coincident with the long-axis PET axis, and the same correction data is used for the same detection ring. Step S200 comprises: sequentially obtaining all coincidence events between every two adjacent detection rings, selecting one of every two adjacent detection rings as a reference ring and the other as a to-be-calibrated ring, and for each coincidence event, obtaining the first arrival time on the crystal bar of the reference ring and the second arrival time on the crystal bar of the to-be-calibrated ring; step S300 comprises: according to the positional relationship between the current to-be-calibrated ring and the first reference ring, the intra-ring time correction value of each crystal bar on the current to-be-calibrated ring, and the peak value of the difference between the first arrival time and the second arrival time of all coincidence events of the current to-be-calibrated ring and the photon flight time, obtaining the inter-ring time correction value of each crystal bar of the to-be-calibrated ring.

[0061] Specifically, if the current to-be-calibrated ring is adjacent to the first reference ring, step S300 comprises: obtaining the peak value of the difference between the first arrival time and the second arrival time of all coincidence events of the current to-be-calibrated ring and the photon flight time, and adding the peak value to the intra-ring time correction values of all crystal bars of the to-be-calibrated ring to obtain the inter-ring time correction value.

[0062] Specifically, if the current to-be-calibrated ring is separated from the first reference ring by one or more other detection rings, step S300 comprises: obtaining the peak value of the difference between the first arrival time and the second arrival time of all coincidence events of the one or more other detection rings and the photon flight time, and obtaining the peak value of the difference between the first arrival time and the second arrival time of the coincidence events corresponding to the current to-be-calibrated crystal bar and the photon flight time; all peak values are added to the intra-ring time correction values of all crystal bars of the current to-be-calibrated ring to obtain the inter-ring time correction value of each crystal bar.

[0063] As a specific example of the above examples, taking the first detection ring as the first reference ring and the second detection ring as the to-be-corrected ring, the linear source is placed between the first detection ring and the second detection ring, and the response lines on the two ends of the first detection ring and the second detection ring are obtained. For each response line, the first arrival time, the second arrival time and the photon flight time are obtained. The first difference value is obtained by subtracting the second arrival time and the photon flight time from the first arrival time. The first difference value corresponding to all response lines is obtained. The first peak value of all first difference values is obtained. The first peak value can be obtained by making a histogram of all first difference values. The first peak value is the calibration data of the current to-be-corrected ring. The first peak value is added to the inter-ring time correction value of the corresponding crystal bar of the second detection ring. The second peak value is obtained by taking the second peak value of all second difference values. The first peak value and the second peak value are added to the intra-ring time correction value of all crystal bars of the third detection ring to obtain the inter-ring time correction value of each crystal bar. The same operation is performed on all crystal bars of all to-be-corrected rings to perform inter-ring time correction on all crystal bars.

[0064] In addition, different from all the above examples, the application can also take a non-end detection ring as the first reference ring. For example, taking the second detection ring as the reference ring, the inter-ring time correction of other detection rings can be performed in turn to the two sides according to the steps in the above examples.

[0065] The above time correction method provided by the application first performs intra-ring time correction, and then performs inter-ring time correction on each detection ring by obtaining the single-event arrival time of the inter-ring coincidence event and combining the single-event arrival time and the intra-ring time correction value. Since the length of the existing linear source can basically cover a single detection ring, the length of the linear source provides a basis for obtaining the inter-ring coincidence event. By combining the inter-ring coincidence event information, the inter-ring time correction is not limited to the length of the linear source, thereby improving the quality of the overall time correction of the digital PET system, which is beneficial to improving the image quality and reducing the radiation dose, and at the same time, the inter-ring time correction of the long-axis PET is realized at the lowest cost.

[0066] In addition, by collecting the photon flight time, the accuracy of the inter-ring time correction can be further improved, and the requirement for the refinement of the operation in the detection process is reduced.

[0067] Based on the description of the above time correction method embodiments, the present application further provides a time correction device. The device can include devices (including distributed systems), software (applications), modules, components, servers, clients, etc. using the methods described in the embodiments of the present application, and devices combined with necessary implementation hardware. Based on the same innovative concept, the device in one or more embodiments provided by the embodiments of the present application is described in the following embodiments. Since the implementation scheme of the device to solve the problem is similar to the method, the implementation of the specific device in the embodiments of the present application can be referred to the implementation of the foregoing method, and the repeated parts will not be described herein. The term "module" or "module" used below can be a combination of software and / or hardware that can implement a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware, or a combination of software and hardware can also be implemented.

[0068] Figure 7 For the structure diagram of the time correction device in one of the embodiments of the present application, in one of the embodiments, the time correction device 700 can include an intra-ring correction module 710, a data acquisition module 720, and an inter-ring correction module 730. Among them, the intra-ring correction module 710 is configured to sequentially perform intra-ring time correction on the crystal bars of the plurality of detection rings to obtain intra-ring time correction values of all crystal bars; the data acquisition module 720 is configured to sequentially acquire all coincidence events between two adjacent detection rings, and acquire single event arrival time of each coincidence event on the crystal bar; the inter-ring correction module 730 is configured to perform inter-ring time correction on the plurality of detection rings according to the position of the current ring to be calibrated, the intra-ring time correction value, and the peak value of the difference between the two single event arrival times of each coincidence event.

[0069] Among them, the method and device provided by the present application can be applied to long-axis PET, and the long-axis PET includes a plurality of detection rings arranged coaxially. For example, a long-axis PET includes two detection rings, and another long-axis PET includes four detection rings. Each detection ring includes 12 or 24 or 48 detectors, each detector includes an 8x8 crystal bar array or a 12x12 crystal bar array, and of course each detector also includes a photoelectric device and a circuit. Of course, those skilled in the art can understand that the number of detection rings, the number of detectors, and the number of crystal bars can be expanded.

[0070] Specifically, in one example of the present application, referring to Figure 3The line source is placed in the field of view of each detection ring in turn to collect data, and the time of each crystal strip is corrected according to the collected data to obtain the in-ring time correction value of each crystal strip. It should be particularly pointed out that the in-ring time correction values of each crystal strip are generally not completely the same due to hardware limitations. When acquiring all coincidence events between two adjacent detection rings, the line source is placed between the two adjacent detection rings, and the two ends of the line source are required to enter the detection field of view of the two detection rings respectively to ensure that sufficient data is collected. Preferably, the length of the line source in the field of view of the two detection rings is the same.

[0071] Preferably, the line source is arranged parallel to the axial direction of the detection ring, and more preferably, the line source is arranged coincident with the axis of the detection ring.

[0072] Preferably, the length of the line source is substantially the same as the axial length of a single detection ring, or slightly larger than the axial length of a single detection ring, for example, substantially the same as the sum of the length of a single detection ring and the length of the gap on both sides thereof.

[0073] Optionally, the in-ring time correction of each detection ring can be performed using existing time correction methods, for example, according to the method described in CN202211731787.X. Of course, those skilled in the art can understand that other methods capable of achieving in-ring time correction in the prior art can also be used.

[0074] The in-ring time correction of each detection ring can be performed using existing time correction methods, for example, according to the method described in CN202211731787.X. Of course, those skilled in the art can understand that other methods capable of achieving in-ring time correction in the prior art can also be used.

[0075] Preferably, in order to reduce the data amount and optimize the data processing speed, in one example of the present application, the data acquisition module 720 is configured to: screen the coincidence events, eliminate the coincidence events corresponding to the response lines with both ends in the same detection ring and the response lines not passing through the source, and acquire the single event arrival time of the remaining coincidence events on the crystal strip. The purpose of this example is to make data acquisition for inter-ring event coincidence, therefore, only the coincidence events occurring between rings are needed, which is reflected on the response line as the two ends of the response line being on two different detection rings, in addition, the events not passing through the source are generally considered to be invalid events, and also need to be eliminated.

[0076] Specifically, in the present application, there are multiple ways for inter-ring time correction, different ways are adopted for correction according to whether the axial direction of the line source coincides with the axis of the long-axis PET, different methods are adopted for correction according to different correction standards, for example, all the detectors in each detection ring share a correction value after correction, or all the crystal strips in each detector share a correction value after correction, or a single crystal strip uses a single correction value, and different ways are adopted for correction according to the positional relationship between the ring to be corrected and the first reference ring.

[0077] Illustratively, in one example of the present application, the axial direction of the line source coincides with the axis of the long-axis PET, and the same detection ring uses the same correction data. The data acquisition module 720 is configured to: sequentially acquire all coincidence events between two adjacent detection rings, select one of the two adjacent detection rings as a reference ring and the other as a ring to be corrected, and for each coincidence event, acquire the first arrival time on the crystal strip of the reference ring and the second arrival time on the crystal strip of the ring to be corrected; the inter-ring correction module 730 is configured to: according to the positional relationship between the current ring to be corrected and the first reference ring, the intra-ring time correction value of each crystal strip on the current ring to be corrected, and the peak value of the difference between the first arrival time and the second arrival time of all coincidence events on the current ring to be corrected, obtain the inter-ring time correction value of each crystal strip of the ring to be corrected.

[0078] Specifically, if the current ring to be corrected is adjacent to the first reference ring, the inter-ring correction module 730 is configured to: acquire the peak value of the difference between the first arrival time and the second arrival time of all coincidence events on the current ring to be corrected, and add the peak value to the intra-ring time correction value of all crystal strips of the ring to be corrected to obtain the inter-ring time correction value.

[0079] Specifically, if the current crystal ring to be corrected is separated from the first reference ring by one or more other crystal rings, the inter-ring correction module 730 is configured to: obtain the peak value of the difference between the first arrival time and the second arrival time of all coincidence events of the one or more other crystal rings, and obtain the peak value of the difference between the first arrival time and the second arrival time of the coincidence events corresponding to the current crystal ring to be corrected; and add all the peak values to the inter-ring time correction value of each crystal bar of the current crystal ring to be corrected.

[0080] As a specific example of the above example, the first crystal ring is taken as the first reference ring, the second crystal ring is taken as the crystal ring to be corrected, the line source is placed between the first crystal ring and the second crystal ring, and the response lines on the two ends of the first crystal ring and the second crystal ring are obtained. For each response line, the first arrival time and the second arrival time are obtained, the first arrival time is subtracted from the second arrival time to obtain the first difference value, the first difference value corresponding to all the response lines is obtained, the first peak value of all the first difference values is obtained, the first peak value can be obtained by making a histogram of all the first difference values, and the first peak value is the calibration data of the current crystal ring to be corrected. The first peak value is added to the inter-ring time correction value of the corresponding crystal bar of the second crystal ring. The second correction takes the second crystal ring as the reference ring, and the third crystal ring as the crystal ring to be corrected. The line source is placed between the second crystal ring and the third crystal ring, and the response lines on the two ends of the second crystal ring and the third crystal ring are obtained. For each response line, the first arrival time and the second arrival time are obtained, the first arrival time is subtracted from the second arrival time to obtain the second difference value, the second difference value corresponding to all the response lines is obtained, the second peak value of all the second difference values is obtained, the first peak value and the second peak value are added to the inter-ring time correction value of each crystal bar of the third crystal ring, and the same operation is performed on all the crystal bars of all the crystal rings to be corrected to perform inter-ring time correction on all the crystal bars. For different crystal rings, the weights of different difference values can be the same or different.

[0081] Exemplarily, in one example of the present application, the axis of the line source is not coincident with the long-axis PET axis, and the same correction data is used for the same detection ring. The data acquisition module 720 is configured to: sequentially acquire all coincidence events between every two adjacent detection rings, select one of the two adjacent detection rings as a reference ring and the other as a to-be-corrected ring, and for each coincidence event, acquire the first arrival time on the crystal bar of the reference ring and the second arrival time on the crystal bar of the to-be-corrected ring; and the inter-ring correction module 730 is configured to: according to the positional relationship between the current to-be-corrected ring and the first reference ring, the intra-ring time correction value of each crystal bar on the current to-be-corrected ring, and the peak value of the difference between the first arrival time and the second arrival time of all coincidence events on the current to-be-corrected ring and the photon flight time, obtain the inter-ring time correction value of each crystal bar on the to-be-corrected ring.

[0082] Specifically, if the current to-be-corrected ring is adjacent to the first reference ring, the inter-ring correction module 730 is configured to: acquire the peak value of the difference between the first arrival time and the second arrival time of all coincidence events on the current to-be-corrected ring and the photon flight time, and add the peak value to the intra-ring time correction value of all crystal bars on the to-be-corrected ring to obtain the inter-ring time correction value.

[0083] Specifically, if the current to-be-corrected ring is adjacent to the first reference ring, the inter-ring correction module 730 is configured to: acquire the peak value of the difference between the first arrival time and the second arrival time of all coincidence events on the current to-be-corrected ring and the photon flight time, and add the peak value to the intra-ring time correction value of all crystal bars on the to-be-corrected ring to obtain the inter-ring time correction value.

[0084] As a specific example of the above examples, taking the first detection ring as the first reference ring and the second detection ring as the to-be-corrected ring, the line source is placed between the first detection ring and the second detection ring, and the response lines on the two ends of the first detection ring and the second detection ring are obtained. For each response line, the first arrival time, the second arrival time and the photon flight time are obtained. The first difference value is obtained by subtracting the second arrival time and the photon flight time from the first arrival time. The first difference value corresponding to all response lines is obtained. The first peak value of all first difference values is taken. The first peak value can be obtained by making a histogram of all first difference values. The first peak value is the calibration data of the current to-be-corrected ring. The first peak value is added to the inter-ring time correction value of the corresponding crystal bar of the second detection ring. The second difference value is obtained by subtracting the second arrival time and the photon flight time from the first arrival time. The second peak value of all second difference values is taken. The first peak value and the second peak value are added to the intra-ring time correction value of all crystal bars of the third detection ring to obtain the inter-ring time correction value of each crystal bar. The same operation is performed on all crystal bars of all to-be-corrected rings to perform inter-ring time correction on all crystal bars.

[0085] In addition, different from all the above examples, the application can also take a non-end detection ring as the first reference ring. For example, taking the second detection ring as the reference ring, the inter-ring time correction of other detection rings can be performed to the two sides in turn according to the steps in the above examples.

[0086] The above time correction device provided by the application first performs intra-ring time correction, and then performs inter-ring time correction on each detection ring by obtaining the single-event arrival time of the inter-ring coincidence event and combining the single-event arrival time and the intra-ring time correction value. Since the length of the existing line source can basically cover a single detection ring, the length of the line source provides a basis for obtaining the inter-ring coincidence event. By combining the inter-ring coincidence event information, the inter-ring time correction is not limited to the length of the line source, thereby improving the quality of the overall time correction of the digital PET system, which is beneficial to improving the image quality and reducing the radiation dose, and at the same time, the inter-ring time correction of the long-axis PET is realized at the lowest cost.

[0087] It should be understood that, Figure 7The apparatuses and modules thereof shown can be implemented in various ways. For example, in some embodiments, the apparatuses and modules thereof can be implemented in hardware, software, or a combination of software and hardware. The hardware portion can be implemented with special logic, while the software portion can be stored in memory and executed by suitable instruction execution apparatuses, such as a microprocessor or specially designed hardware. Those skilled in the art can understand that the above-mentioned methods and apparatuses can be implemented using computer-executable instructions and / or included in processor control codes, such as provided on a carrier medium, such as a disk, CD or DVD-ROM, programmable memory, such as read-only memory (firmware), or data carrier, such as an optical or electronic signal carrier. The apparatuses and modules thereof of the present application can be implemented not only in hardware circuitry, such as very large scale integrated circuits or gate arrays, such as logic chips, transistors, etc., or programmable hardware devices, such as field programmable gate arrays, programmable logic devices, etc., but also in software, for example, executed by various types of processors, and can also be implemented by a combination of the above-mentioned hardware circuitry and software (e.g., firmware).

[0088] It should be noted that the above description of the modules is for convenience of description only and does not limit the present application to the scope of the embodiments. It can be understood that, for those skilled in the art, after understanding the principles of the apparatus, the modules can be combined arbitrarily or connected to other modules to form subsystems without departing from the principles. For example, the modules can share a storage module, and each module can have its own storage module. Variations such as these are within the scope of the present application.

[0089] Figure 8 A schematic diagram of a time correction system for implementing the time correction method in one of the embodiments of the present application is shown. Referring to Figure 8 , the time correction system S00 can include a processing component S20, which further includes one or more processors, and a memory resource represented by a memory S22, for storing instructions, such as application programs, executable by the processors of the processing component S20. The application programs stored in the memory S22 can include one or more instructions, each module corresponding to a set of instructions. In addition, the processing component S20 is configured to execute the instructions to perform the above-mentioned time correction method.

[0090] The operations and / or methods described in the embodiments of the specification implemented by one processor can also be implemented by multiple processors collectively or independently. For example, if the processor of the processing device performs steps 100~steps 300 in the specification of the present application, it should be understood that steps 100~steps 300 can also be performed by two different processors of the processing device collectively or independently (for example, the first processor performs steps 100~steps 200, the second processor performs step 300, or the first and second processors collectively perform steps 100~steps 300).

[0091] The time correction system S00 can also include a power component S24 configured to perform power management of the time correction system S00, a wired or wireless network interface S26 configured to connect the time correction system S00 to a network, and an input / output (I / O) interface S28. The time correction system S00 can operate based on an operating system stored in the memory S22, such as Windows Server, Mac OS X, Unix, Linux, FreeBSD or the like.

[0092] In an exemplary embodiment, a computer readable storage medium including instructions, such as the memory S22 including instructions, is also provided, which can be executed by the processor of the time correction system S00 to complete the above method. The storage medium can be a computer readable storage medium, for example, the computer readable storage medium can be ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk and optical data storage device, etc.

[0093] In an exemplary embodiment, a computer program product is also provided, which includes instructions that can be executed by the processor of the time correction system S00 to complete the above method.

[0094] In one embodiment, a computer device, which can be a server, is provided, and its internal structure diagram can be as shown in Figure 9 Figure 9 ​The internal structure diagram of the computer device in one of the embodiments of the present application is shown. The computer device comprises a processor, a memory and a network interface connected through a system bus. The processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device comprises a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for running the operating system and the computer program in the non-volatile storage medium. The database of the computer device is configured to store data related to a user and a task used in the time correction method. The network interface of the computer device is configured to communicate with an external terminal through a network connection. The computer program is executed by the processor to implement a time correction method.

[0095] Those skilled in the art can understand that, Figure 9 The structure shown in the figure is only a block diagram of part of the structure related to the scheme of the present application, and does not constitute a limitation on the computer device to which the scheme of the present application is applied. The specific computer device can comprise more or fewer components than those shown in the figure, or some components can be combined, or have a different arrangement of components.

[0096] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer readable storage medium, and when executed, can include the processes of the above-mentioned embodiment methods. Any reference to memory, database or other medium used in each embodiment provided by the present 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 storage, high-density embedded non-volatile memory, resistive memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration but not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc. The database involved in each embodiment provided by the present application can include at least one of a relational database and a non-relational database. The non-relational database can include a distributed database based on a block chain, etc., without being limited thereto. The processor involved in each embodiment provided by the present application can be a general-purpose processor, a central processing unit, a graphics processing unit, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., without being limited thereto.

[0097] Each embodiment in the specification is described in a progressive manner, and the same or similar parts between each embodiment can be referred to each other. Each embodiment focuses on the difference from other embodiments. In particular, for hardware+program type embodiments, since they are basically similar to method embodiments, they are described more simply, and the relevant parts can be referred to the part of the method embodiment.

[0098] It should be noted that the apparatus, electronic device, server and the like described above according to the description of the method embodiments can also include other implementations, and the specific implementation can refer to the description of the related method embodiments. Meanwhile, the mutual combination of the features of each method and the device, apparatus, server embodiments constitutes a new embodiment, which still falls within the scope of the embodiments covered by the present application, and is not described one by one here.

[0099] In the description of the present specification, the description of the terms "one embodiment", "an embodiment", and / or "some embodiments", "some embodiments", "other embodiments", "ideal embodiment" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example, and certain features, structures or characteristics in one or more embodiments of the present specification can be properly combined.

[0100] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered that it is within the scope of the present specification.

[0101] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of the patent of the present application should be subject to the appended claims.

[0102] The basic concepts have been described herein, and it is obvious that the above detailed disclosure is only as an example, and does not constitute a limitation on the present specification. Although it is not explicitly stated herein, those skilled in the art can make various modifications, improvements and corrections to the present specification. Such modifications, improvements and corrections are suggested in the present specification, so such modifications, improvements and corrections still fall within the spirit and scope of the exemplary embodiments of the present specification.

[0103] Moreover, those skilled in the art will appreciate that the various aspects of the disclosure can be illustrated and described in connection with a number of various kinds of systems or circumstances, including any new and useful processes, machines, products, or compositions of matter, or any new and useful improvements thereof, as defined by the plain language of the claims. Accordingly, the various aspects of the disclosure can be performed entirely by hardware, entirely by software (including firmware, resident software, microcode, etc.), or by combinations of hardware and software. The above described hardware or software can be referred to as a "data block", "module", "engine", "component", "element", or "system". Furthermore, the various aspects of the disclosure can be embodied as computer products including computer readable program coding.

[0104] Computer storage media can include a propagated data signal with computer program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal can take any of a variety of forms, including but not limited to electro-magnetic, optical, or any suitable combination thereof. Computer storage media can be any media that can be accessed by a computer. As used herein, "computer storage media" includes one or more of volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program code, or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, solid state drives (SSDs) that are based on RAM, flash memory or other solid state memory

[0105] Computer program code for carrying out operations of the aspects of the disclosure can be written in any one or more of a variety of programming languages, including an object oriented programming language such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C#, VB.NET, Python, or a conventional procedural programming language such as C language, Visual Basic, Fortran 3003, Perl, COBOL 3002, PHP, ABAP, a dynamic programming language such as Python, Ruby and Groovy, or other programming languages. The program code can execute entirely on the user's computer, or it can be executed as a stand-alone software package, or it can execute partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider), or in a cloud computing environment or as a service such as Software as a Service (SaaS).

[0106] Furthermore, the order of the processing elements and sequences described in this specification are not intended to be construed as a limitation, unless specifically stated, but are included to provide a complete description of one or more embodiments of the present specification. Regardless of the particular sequence of processing elements and sequences, however, the description herein of a process should be understood to include any and all combinations of one or more elements of a process independently selected from each sequence. For example, although the system components described above can be implemented by hardware devices, they can also be implemented by software solutions, such as installing the described system on an existing server or mobile device.

[0107] Similarly, it is to be noticed that the term "comprising", used in the description, is not intended to exclude other elements or steps. It is to be understood that the description and the examples are intended to be illustrative, but not limiting, of the scope of the present specification. Thus, the scope of the present specification should be given by the appended claims, along with their full scope of equivalents, and not by an restricting interpretation of the description or the examples.

[0108] Some embodiments use numerical designations to describe components, quantities of attributes. It should be understood that such numerical designations used in the description of embodiments are, in some examples, modified by the adjectives "about," "approximately," or "generally." Unless otherwise stated, "about," "approximately," or "generally" indicates that the described numerical value allows for a ±20% variation. Accordingly, in some embodiments, numerical parameters in the description and claims are approximations, and as such, the approximations can vary depending on the desired properties sought to be obtained by the individual embodiments. In some embodiments, numerical parameters are determined by the use of common rounding techniques. Although the numerical ranges and parameters setting forth the broad scope of the embodiments recited in this specification are approximations, unless otherwise indicated, these numerical values are approximations.

[0109] Each patent, patent application, publication, document, article, book, specification, and other material cited in this specification is hereby incorporated by reference in its entirety for all purposes to the same extent as if each individual publication, document, article, book, specification or other material were specifically and individually indicated to be incorporated by reference in its entirety for its cited and recited teachings. For contrary or inconsistent definitions or teachings of the incorporated material with the content of this specification, the content of this specification shall control. In the event of a discrepancy between the content of this specification and the incorporated material, the content of this specification shall control.

[0110] Finally, it should be understood that the embodiments described herein are only given by way of example and that other modifications can occur to persons skilled in the art. Therefore, the scope of the present description is not intended to be limited to the embodiments described herein but is only limited by the claims that follow.

Claims

1. A time correction method, characterized by, The time correction method comprises: Step S100: sequentially performing intra-ring time correction on the crystal bars of the plurality of detection rings to obtain intra-ring time correction values of all the crystal bars; Step S200: sequentially obtaining all coincidence events between every two adjacent detection rings, and obtaining single event arrival times of each coincidence event on the crystal bars; Step S300: performing inter-ring time correction on the plurality of detection rings according to the position of the current ring to be calibrated, the intra-ring time correction values, and the peak value of the difference between the two single event arrival times of each coincidence event.

2. The time correction method according to claim 1, characterized in that, Step S200 comprises: sequentially obtaining all coincidence events between every two adjacent detection rings, selecting one of the two adjacent detection rings as a reference ring and the other as a ring to be calibrated, and for each coincidence event, obtaining a first arrival time on the crystal bars of the reference ring and a second arrival time on the crystal bars of the ring to be calibrated; Step S300 comprises: obtaining the inter-ring time correction value of each crystal bar of the ring to be calibrated according to the positional relationship between the current ring to be calibrated and the first reference ring, the intra-ring time correction value of each crystal bar on the current ring to be calibrated, and the peak value of the difference between the first arrival time and the second arrival time of all coincidence events on the current ring to be calibrated.

3. The time correction method according to claim 2, characterized in that, If the current ring to be calibrated is adjacent to the first reference ring, step S300 comprises: obtaining the peak value of the difference between the first arrival time and the second arrival time of all coincidence events on the current ring to be calibrated, and adding the peak value to the intra-ring time correction value of all crystal bars of the ring to be calibrated to obtain the inter-ring time correction value.

4. The time correction method according to claim 2, characterized in that, If the current ring to be calibrated is separated from the first reference ring by one or more other detection rings, step S300 comprises: obtaining the peak value of the difference between the first arrival time and the second arrival time of all coincidence events of the one or more other detection rings, and obtaining the peak value of the difference between the first arrival time and the second arrival time corresponding to the coincidence event of the current crystal bar to be deposited; adding all the peak values to the intra-ring time correction value of all crystal bars of the current ring to be calibrated to obtain the inter-ring time correction value of each crystal bar.

5. The time correction method of claim 1, wherein, Step S200 comprises: sequentially obtaining all coincidence events between every two adjacent detection rings, selecting one of the two adjacent detection rings as a reference ring and the other as a ring to be calibrated, and for each coincidence event, obtaining a first arrival time on the crystal bars of the reference ring and a second arrival time on the crystal bars of the ring to be calibrated, and obtaining a photon flight time corresponding to the coincidence event; Step S300 comprises: obtaining the inter-ring time correction value of each crystal bar of the ring to be calibrated according to the positional relationship between the current ring to be calibrated and the first reference ring, the intra-ring time correction value of each crystal bar on the current ring to be calibrated, and the peak value of the difference between the first arrival time minus the second arrival time and the photon flight time of all coincidence events on the current ring to be calibrated.

6. The time correction method according to claim 5, characterized in that, If the current ring to be calibrated is adjacent to the first reference ring, step S300 comprises: The peak value of the difference between the first arrival time and the second arrival time and the photon flight time of all coincidence events of the current to-be-corrected ring is obtained, and the peak value is added to the inter-ring time correction value of all crystal bars of the to-be-corrected ring.

7. The time correction method of claim 5, wherein, If the current to-be-corrected ring is separated from the first reference ring by one or more other detection rings, step S300 comprises: The peak value of the difference between the first arrival time and the second arrival time and the photon flight time of all coincidence events of the one or more other detection rings is obtained, and the peak value of the difference between the first arrival time and the second arrival time and the photon flight time of the coincidence events corresponding to the current to-be-corrected crystal bar is obtained. All peak values are added to the intra-ring time correction value of all crystal bars of the current to-be-corrected ring to obtain the inter-ring time correction value of each crystal bar.

8. The time correction method according to any one of claims 2 to 7, characterized in that, The inter-ring time correction is performed with the first detection ring as the reference ring and the second detection ring as the to-be-corrected ring, and then the inter-ring time correction is performed with the previous detection ring as the reference ring and the subsequent detection ring as the to-be-corrected ring in turn.

9. The time correction method according to any one of claims 2 to 7, characterized in that, The inter-ring time correction is performed with any detection ring as the reference ring and the detection ring adjacent to it on one side / two sides as the to-be-corrected ring, and when there is an uncorrected detection ring on one side or both sides of the corrected detection ring, the inter-ring time correction is performed with the corrected detection ring as the reference ring and the uncorrected detection ring as the to-be-corrected ring.

10. The time correction method of claim 1, wherein, Step S200 comprises: The coincidence events are screened, and the response lines corresponding to the coincidence events whose two ends are in the same detection ring and the response lines not passing through the source are removed, and the single-event arrival time of the remaining coincidence events on the crystal bar is obtained.

11. The time correction method of claim 1, wherein, Both step S100 and step S200 are performed by data acquisition of line source detection to calculate the intra-ring time correction value and obtain the single-event arrival time.

12. The time correction method according to claim 11, characterized in that, In step S100, the line source is placed in the detection field of view of each detection ring in turn. In step S200, the line source is placed between every two adjacent detection rings, and the two ends of the line source are located in the partial detection field of view of the two detection rings, respectively.

13. The time correction method of claim 11, wherein, The arrangement direction of the line source is parallel to the axial direction of the detection ring.

14. The time correction method of claim 11, wherein, The arrangement direction of the line source coincides with the axial direction of the detection ring.

15. A time correction device, characterized by The time correction device comprises: an intra-ring correction module configured to perform intra-ring time correction on the crystal bars of the plurality of detection rings in turn to obtain the intra-ring time correction value of all crystal bars; a data acquisition module configured to acquire all coincidence events between every two adjacent detection rings in turn, and to obtain the single-event arrival time of each coincidence event on the crystal bar; an inter-ring correction module configured to perform inter-ring time correction on the plurality of detection rings according to the position of the current to-be-corrected ring, the intra-ring time correction value, and the peak value of the difference between the two single-event arrival times of each coincidence event.

16. The time correction apparatus of claim 15, wherein The data acquisition module is configured to: acquire all coincidence events between every two adjacent detection rings in turn, select one of the two adjacent detection rings as a reference ring and the other as a to-be-corrected ring, and for each coincidence event, obtain the first arrival time on the crystal bar of the reference ring and the second arrival time on the crystal bar of the to-be-corrected ring. The inter-ring correction module is configured to: according to the positional relationship between the current to-be-corrected ring and the first reference ring, the intra-ring time correction value of each crystal strip on the current to-be-corrected ring, and the peak value of the difference between the first arrival time and the second arrival time of all coincidence events on the current to-be-corrected ring, obtain the inter-ring time correction value of each crystal strip of the to-be-corrected ring.

17. The time correction apparatus of claim 16, wherein, If the current to-be-corrected ring is adjacent to the first reference ring, the inter-ring correction module is configured to: obtain the peak value of the difference between the first arrival time and the second arrival time of all coincidence events on the current to-be-corrected ring, and add the peak value to the intra-ring time correction value of all crystal strips of the to-be-corrected ring to obtain the inter-ring time correction value.

18. The time correction apparatus of claim 16, wherein, If the current to-be-corrected ring is separated from the first reference ring by one or more other detection rings, the inter-ring correction module is configured to: obtain the peak value of the difference between the first arrival time and the second arrival time of all coincidence events of the one or more other detection rings, and obtain the peak value of the difference between the first arrival time and the second arrival time corresponding to the coincidence event deposited by the current to-be-corrected crystal strip; add all the peak values to the intra-ring time correction value of all crystal strips of the current to-be-corrected ring to obtain the inter-ring time correction value of each crystal strip.

19. The time correction apparatus of claim 15, wherein, The data acquisition module is configured to: sequentially acquire all coincidence events between two adjacent detection rings, select one of the two adjacent detection rings as a reference ring and the other as a to-be-corrected ring, for each coincidence event, acquire the first arrival time on the crystal strip of the reference ring and the second arrival time on the crystal strip of the to-be-corrected ring, and acquire the photon flight time corresponding to the coincidence event. The inter-ring correction module is configured to: according to the positional relationship between the current to-be-corrected ring and the first reference ring, the intra-ring time correction value of each crystal strip on the current to-be-corrected ring, and the peak value of the difference between the first arrival time and the second arrival time of all coincidence events on the current to-be-corrected ring, obtain the inter-ring time correction value of each crystal strip of the to-be-corrected ring.

20. The time correction apparatus of claim 19, wherein, If the current to-be-corrected ring is adjacent to the first reference ring, the inter-ring correction module is configured to: obtain the peak value of the difference between the first arrival time and the second arrival time of all coincidence events on the current to-be-corrected ring, and add the peak value to the intra-ring time correction value of all crystal strips of the to-be-corrected ring to obtain the inter-ring time correction value.

21. The time correction apparatus of claim 19, wherein, If the current to-be-corrected ring is separated from the first reference ring by one or more other detection rings, the inter-ring correction module is configured to: obtain the peak value of the difference between the first arrival time and the second arrival time of all coincidence events of the one or more other detection rings, and obtain the peak value of the difference between the first arrival time and the second arrival time corresponding to the coincidence event deposited by the current to-be-corrected crystal strip; add all the peak values to the intra-ring time correction value of all crystal strips of the current to-be-corrected ring to obtain the inter-ring time correction value of each crystal strip.

22. The time correction apparatus of claim 15, wherein, The data acquisition module is configured to: screen the coincidence events, eliminate the response lines with both ends in the same detection ring and the response lines not passing through the source in the response lines corresponding to the coincidence events, and acquire the single event arrival time of the remaining coincidence events on the crystal strip.

23. A computer storage medium having stored thereon a computer program, characterized in that The computer program, when executed by a processor, implements the steps of the time correction method of any one of claims 1 to 14.

24. A computer program product, characterised in that, The computer program or instructions, when executed by a processor, implement the steps of the time correction method of any one of claims 1 to 14.

25. A digital PET system characterized by, The time correction is performed by using the time correction device of any one of claims 15 to 22. The time correction is performed by using the time correction device of any one of claims 15 to 22.

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