Coincidence event determination method and device, PET imaging method and controller

Abstract

The invention relates to a coincidence event determination method and device, a PET imaging method and a controller. The method comprises the following steps: acquiring a first energy window and a second energy window which are asymmetric; under the condition that the first detection energy meeting the first energy window and the second detection energy meeting the second energy window are detected, determining a first detector which detects the first detection energy and a second detector which detects the second detection energy; and obtaining a target coincidence event according to the coincidence event jointly detected by the first detector and the second detector. By adopting the method, the detection efficiency of determining the true coincidence event can be improved.

Description

Technical Field

[0001] The present application relates to the field of PET imaging technology, and in particular to a coincidence event determination method, device, PET imaging method and controller. Background Art

[0002] With the development of medical imaging technology, the application of positron emission computed tomography (PET) is becoming more and more widespread. During the PET scanning process, when two 511keV gamma (γ) photons are collected by a pair of PET detectors within a certain time window, an event marker is generated, which is called a coincidence event. Coincidence events can be divided into true coincidence events, scattered coincidence events and random coincidence events. For example, if at least one photon is scattered once or multiple times by the medium, such an event is called a scattered coincidence event. However, only true coincidence events can accurately reflect the positioning information of annihilation events.

[0003] In the prior art, the accuracy of determining true coincidence events is usually improved by setting energy windows. Currently, this is mainly achieved by using symmetrical energy windows for PET detectors, that is, when the energies of two PET detectors meet the same energy window, the received coincidence events are regarded as true coincidence events.

[0004] However, the applicant discovered during the implementation process that the prior art had the problem of low efficiency in determining true matching events. Summary of the invention

[0005] Based on this, it is necessary to provide a coincidence event determination method, device, PET imaging method and controller that can improve the efficiency of true coincidence event detection in order to address the above technical problems.

[0006] In a first aspect, the present application provides a method for determining a compliance event, the method comprising:

[0007] Acquire an asymmetric first energy window and a second energy window;

[0008] In case of detecting a first detection energy satisfying a first energy window and a second detection energy satisfying a second energy window, determining a first detector that detected the first detection energy and a second detector that detected the second detection energy;

[0009] A target coincidence event is obtained according to the coincidence event detected jointly by the first detector and the second detector.

[0010] In one embodiment, the first energy window includes a first low energy discrimination threshold; the second energy window includes a second low energy discrimination threshold;

[0011] Acquiring an asymmetric first energy window and a second energy window, comprising:

[0012] Acquire different first low energy discrimination threshold and second low energy discrimination threshold;

[0013] Based on the first low energy discrimination threshold, a first energy window is obtained;

[0014] A second energy window is obtained according to the second low energy discrimination threshold.

[0015] In one embodiment, detecting a first detection energy satisfying a first energy window and a second detection energy satisfying a second energy window comprises:

[0016] Using detection energy greater than a first low energy discrimination threshold as first detection energy;

[0017] The detection energy greater than the second low energy discrimination threshold is used as the second detection energy.

[0018] In one embodiment, obtaining different first low energy discrimination threshold and second low energy discrimination threshold includes:

[0019] Acquire a different first low energy initial threshold and a second low energy initial threshold, and acquire a same first low energy standard threshold and a second low energy standard threshold;

[0020] Acquire an initial coincidence event determined according to a first low energy initial threshold and a second low energy initial threshold;

[0021] Acquire a standard compliance event determined according to a first low energy standard threshold and a second low energy standard threshold;

[0022] According to the accuracy of the initial coincidence event and the standard coincidence event, the first low energy initial threshold and the second low energy initial threshold are adjusted to obtain different first low energy discrimination thresholds and second low energy discrimination thresholds.

[0023] In one embodiment, obtaining a target matching event according to matching events detected by the first detector and the second detector includes:

[0024] Acquire a first detector corresponding to the detected first detection energy as a target first detector;

[0025] Acquire a first detection time at which the first detection energy is detected, and determine a second detector at which the second detection energy is detected at a second detection time as a target second detector; the first detection time and the second detection time are times within a preset time window;

[0026] A target coincidence event is obtained according to the coincidence events detected by the target first detector and the target second detector.

[0027] In one embodiment, obtaining a target matching event according to matching events detected by the first detector and the second detector includes:

[0028] Performing Monte Carlo simulation on a preset simulated test object to obtain a scattering correction coefficient;

[0029] According to the scatter correction coefficient, the coincidence event detected by the first detector and the second detector is corrected to obtain the target coincidence event.

[0030] In one embodiment, obtaining an asymmetric first energy window and a second energy window includes:

[0031] In response to a trigger instruction of the asymmetric energy window mode, acquiring the asymmetric energy window mode;

[0032] When the imaging mode is an asymmetric energy window mode, an asymmetric first energy window and a second energy window are acquired.

[0033] A PET imaging method, the method comprising:

[0034] Obtaining a target matching event of the object to be detected, wherein the target matching event is obtained according to the matching event determination method described above;

[0035] Determine target imaging data of the object to be detected according to the target coincidence event;

[0036] Image reconstruction is performed based on the target imaging data to obtain a target image of the object to be detected.

[0037] In a second aspect, the present application further provides a conforming event determination device, the device comprising:

[0038] An energy window acquisition module, used for acquiring an asymmetric first energy window and a second energy window;

[0039] a detector determination module, for determining a first detector that detects the first detection energy and a second detector that detects the second detection energy when a first detection energy that satisfies the first energy window and a second detection energy that satisfies the second energy window is detected;

[0040] The matching event determination module is used to obtain a target matching event according to the matching events detected by the first detector and the second detector.

[0041] In a third aspect, the present application further provides a controller including a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0042] In a fourth aspect, the present application further provides a computer-readable storage medium, on which a computer program is stored, and the computer program implements the steps of the above method when executed by a processor.

[0043] In a fifth aspect, the present application also provides a computer program product, which includes a computer program, and the computer program implements the steps of the above method when executed by a processor.

[0044] The above-mentioned coincidence event determination method, device, PET imaging method and controller obtain an asymmetric first energy window and a second energy window; and when the first detection energy that meets the first energy window and the second detection energy that meets the second energy window are detected, the first detector that detects the first detection energy and the second detector that detects the second detection energy are determined; the target coincidence event can be obtained according to the coincidence event detected jointly by the first detector and the second detector. Compared with the conventional technology, the present application can expand the energy window to determine the coincidence event by setting an asymmetric first energy window and a second energy window, and can reduce the number of lower energy and avoid the inaccuracy of the coincidence event. Further, the first detector and the second detector can jointly detect the coincidence event that meets the above-mentioned asymmetric energy window as the target coincidence event, and the target coincidence event can be used as a true coincidence event, thereby improving the detection efficiency of determining the true coincidence event. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 A schematic diagram of a flow chart of a method for determining a compliance event in an embodiment;

[0047] Figure 2 A schematic diagram of a flow chart of the steps of obtaining different first low energy discrimination thresholds and second low energy discrimination thresholds in one embodiment;

[0048] Figure 3 A schematic diagram of a process for obtaining target compliance event steps in an embodiment;

[0049] Figure 4 A schematic diagram showing the result of noise equivalent counts changing with the low energy discrimination threshold in another embodiment;

[0050] Figure 5A schematic diagram of the structure of a scatter correction pressure test phantom in one embodiment;

[0051] Figure 6 A schematic diagram of the results of a scatter correction test in one embodiment;

[0052] Figure 7 A schematic diagram of a PET imaging method according to an embodiment;

[0053] Figure 8 is a structural block diagram of a device for determining an event in accordance with an embodiment;

[0054] Fig. 9 FIG. 4 is a diagram showing the internal structure of a controller in one embodiment. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0056] In the PET detection system, the true coincidence event that the PET detector expects to obtain is a coincidence event that is generated by the annihilation of β+ electrons (positively charged beta particles) and does not scatter before entering the PET detector. The energy of the gamma photon of the true coincidence event is 511keV before entering the PET detector, but the detector's detection efficiency for 511keV rays is not 100%, and there is a difference between the full energy peak detection efficiency and the full energy spectrum detection efficiency. The full energy peak detection efficiency refers to the detection efficiency of the PET detector to capture all the energy of 511keV rays, while the full energy spectrum detection efficiency refers to the efficiency of the PET detector to capture a certain amount of energy through interaction with 511keV rays. Since some rays only undergo a small amount of Compton scattering in the PET detector and only deposit part of the energy, there is generally a difference of >20% between the two detection efficiencies. Since the PET detection system detects coincidence events, the difference between the full energy peak detection efficiency and the full energy spectrum detection efficiency for coincidence events can generally reach 40%.

[0057] Although lowering the low energy discrimination threshold of the system energy window can improve the system sensitivity, it will increase scattering and random events, resulting in a decrease in the noise equivalent count rate (NECR). Conversely, increasing the low energy discrimination threshold for a high energy resolution system can increase the system noise equivalent count rate, but it will also reduce the system sensitivity.

[0058] Current PET detectors generally use a symmetric energy window setting, that is, when the energy at both ends of the coincidence is greater than the low energy discrimination threshold, the coincidence event is received: E a >ELLD ∩E b >E LLD , E a 、E b are the energies at both ends, E LLD The low energy discrimination threshold can achieve a balance between system sensitivity and NECR (Noise equivalent count rate) performance, but the symmetric energy window setting still has the problem of low accuracy in determining matching events.

[0059] Based on this, the present application provides a method for determining a conforming event to improve the accuracy of determining a conforming event.

[0060] In an exemplary embodiment, Figure 1 As shown, a method for determining a compliance event is provided. This embodiment uses the method applied to a terminal (such as a computer) as an example. It can be understood that the method can also be applied to a server, and can also be applied to a system including a terminal and a server, and is implemented through the interaction between the terminal and the server. In this embodiment, the method includes the following steps: S102 to S106, wherein:

[0061] S102, acquiring an asymmetric first energy window and a second energy window.

[0062] Wherein, the first energy window and the second energy window can both be pre-set energy windows. The first energy window and the second energy window can be set as two asymmetric energy windows. The energy window may include a low energy discrimination threshold and a high energy discrimination threshold. For example, the energy value limit can be set between the low energy discrimination threshold and the high energy discrimination threshold. The two asymmetric energy windows may be energy windows whose low energy discrimination threshold and / or high energy discrimination threshold are different; for example, the low energy discrimination threshold of the first energy window is different from the low energy discrimination threshold of the second energy window, then the first energy window and the second energy window are two asymmetric energy windows. As an example, the present application sets the low energy discrimination threshold of the first energy window and the low energy discrimination threshold of the second energy window to be different, and the high energy discrimination threshold of the first energy window is the same as the high energy discrimination threshold of the second energy window.

[0063] Exemplarily, the terminal can obtain an asymmetric first energy window and a second energy window pre-set by a user. For example, the terminal can determine a high energy discrimination threshold and a low energy discrimination threshold of the first energy window, and a high energy discrimination threshold and a low energy discrimination threshold of the second energy window, wherein the low energy discrimination threshold of the first energy window and the low energy discrimination threshold of the second energy window are different, as the asymmetric first energy window and the second energy window.

[0064] Optionally, you can set E LLD1 >ELLD2 , where E LLD1 is the low energy discrimination threshold of the first energy window, E LLD2 is the low energy discrimination threshold of the second energy window.

[0065] S104, when a first detection energy satisfying the first energy window and a second detection energy satisfying the second energy window are detected, determine a first detector that detects the first detection energy and a second detector that detects the second detection energy.

[0066] The first detection energy may be a detection energy within a first energy window; the second detection energy may be a detection energy within a second energy window. The first detector may be a detector for detecting the first detection energy, and the energy detected by the first detector satisfies the first energy window. The second detector may be a detector for detecting the second detection energy, and the energy detected by the second detector satisfies the second energy window.

[0067] It is understood that the terms "first", "second", etc. used in this application can be used in this article to describe various words, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element. For example, without departing from the scope of this application, at the current moment, the energy detected by the detector meets the second energy window, then the detector can be used as the second detector; at another moment, the energy detected by the detector meets the first energy window, then the detector can be used as the first detector. At the same moment, the first detector and the second resistance detector are both detectors, but they are not the same detector.

[0068] Exemplarily, a first detection energy satisfying a first energy window and a second detection energy satisfying a second energy window may be determined within a preset time window. The time window may be a preset time range, for example, within the preset time range, the first detector detects the first detection energy satisfying the first energy window, and the second detector detects the second detection energy satisfying the second energy window. The time difference between the first detection energy detected by the first detector and the second detection energy detected by the second detector is within the preset time range.

[0069] In a preset time window, if a first detection energy satisfying a first energy window and a second detection energy satisfying a second energy window are detected, a first detector detecting the first detection energy and a second detector detecting the second detection energy can be determined. Further, a target coincidence event can be determined based on coincidence events corresponding to the first detection energy detected by the first detector and the second detection energy detected by the second detector.

[0070] S106, obtaining a target matching event according to the matching event detected jointly by the first detector and the second detector.

[0071] The target coincidence event may be a coincidence event required for imaging by a PET detection system. For example, the target coincidence event may be a determined true coincidence event.

[0072] Exemplarily, the coincidence event corresponding to the first detection energy detected by the first detector and the coincidence event corresponding to the second detection energy detected by the second detector can be used as the coincidence event detected jointly by the first detector and the second detector. The target coincidence event of the PET detection system can be determined based on the coincidence event detected jointly by the first detector and the second detector. For example, in a preset time window, the first detector detects the first detection energy that satisfies the first energy window, and the second detector detects the second detection energy that satisfies the second energy window, then the coincidence event that the first detector detects the first detection energy and the second detector detects the second detection energy can be used as the target coincidence event.

[0073] Optionally, two different low energy thresholds E can be set LLD1 and E LLD2 , and E LLD1 >E LLD2 . Greater than E LLD1 The event represents the energy spectrum region corresponding to the full energy peak detection efficiency, E LLD1 ~E LLD2 The area is to expand the energy area to improve the system sensitivity, where E LLD1 ~E LLD2 Refers to E LLD1 To E LLD2 In the range of LLD2 And one end is greater than E LLD1 When , the first detector and the second detector can be determined according to the following expression, and the target compliance event can be further determined:

[0074] (E a >E LLD1 ∩E b >E LLD2 )∪(E a >E LLD2 ∩E b >E LLD1 )

[0075] Among them, E LLD1 is the low energy discrimination threshold of the first energy window, E LLD2 is the low energy discrimination threshold of the second energy window. b >E LLD2 When E a is the first detection energy, E b is the second detection energy; E a >ELLD2 When E b is the first detection energy, E a is the second detection energy.

[0076] The above expression can be represented, satisfying E a >E LLD1 ∩E b >E LLD2 , or satisfy E a >E LLD2 ∩E b >E LLD1 , it can be determined that the target meets the event.

[0077] In meeting E a >E LLD1 ∩E b >E LLD2 In the case of a The detector is the first detector, which detects energy E b The detector is the second detector, E a and E b The corresponding detection events can be regarded as target matching events, where E a >E LLD1 ∩E b >E LLD2 Refers to satisfying energy E a >E LLD1 And satisfy the energy E b >E LLD2 In E a >E LLD2 ∩E b >E LLD1 In the case of Eb, the detector that detects Eb is the first detector, and the detector that detects E a The detector is the second detector, E a and E b The corresponding detection events can be regarded as target matching events, where E a >E LLD2 ∩E b >E LLD1 Refers to satisfying energy E a >E LLD2 And satisfy the energy E b >E LLD1 .

[0078] In this embodiment, by acquiring an asymmetric first energy window and a second energy window; and in the case of detecting a first detection energy that satisfies the first energy window and a second detection energy that satisfies the second energy window, determining a first detector that detects the first detection energy and a second detector that detects the second detection energy; it is possible to obtain a target coincidence event based on the coincidence event detected jointly by the first detector and the second detector. Compared with conventional technology, this embodiment, by setting an asymmetric first energy window and a second energy window, can expand the energy window to determine a coincidence event, and can reduce the number of lower energy, avoid the inaccuracy of coincidence events, and further can detect a coincidence event that satisfies the above-mentioned asymmetric energy window by the first detector and the second detector as a target coincidence event, and the target coincidence event can be used as a true coincidence event, thereby improving the detection efficiency of determining a true coincidence event.

[0079] In an exemplary embodiment, the first energy window includes a first low energy discrimination threshold; the second energy window includes a second low energy discrimination threshold;

[0080] Acquiring an asymmetric first energy window and a second energy window, comprising:

[0081] Acquire different first low energy discrimination threshold and second low energy discrimination threshold;

[0082] Based on the first low energy discrimination threshold, a first energy window is obtained;

[0083] A second energy window is obtained according to the second low energy discrimination threshold.

[0084] The first low energy discrimination threshold may be a lower threshold of the first energy window, and the second low energy discrimination threshold may be a lower threshold of the second energy window.

[0085] Exemplarily, a first low energy discrimination threshold and a second low energy discrimination threshold may be obtained, and the first low energy discrimination threshold and the second low energy discrimination threshold may be determined as thresholds with different values. The first low energy discrimination threshold and the second low energy discrimination threshold may be determined after multiple iterations of updates, for example, by receiving a coincidence event according to multiple different first low energy discrimination thresholds and second low energy discrimination thresholds, the system sensitivity and noise equivalent count rate of the PET detection system in this state may be determined, and the first low energy discrimination threshold and the second low energy discrimination threshold may be adjusted according to the system sensitivity and noise equivalent count rate of the PET detection system.

[0086] The first energy window can be determined according to the first low energy discrimination threshold, and the second energy window can be determined according to the second low energy discrimination threshold. For example, the first energy window and the second energy window can be determined according to different first low energy discrimination thresholds and second low energy discrimination thresholds, respectively, and the high energy discrimination threshold of the first energy window and the high energy discrimination threshold of the second energy window can be the same, so that asymmetric first energy windows and second energy windows can be determined.

[0087] Optionally, the relationship between the first low energy discrimination threshold and the second low energy discrimination threshold is as follows: LLD1 >E LLD2 , where E LLD1 is the first low energy discrimination threshold, E LLD2 is the second lowest energy discrimination threshold. LLD1 The coincident events represent the energy spectrum region corresponding to the full energy peak detection efficiency, E LLD1 ~E LLD2 To expand the energy region, to receive more matching events, to improve the system sensitivity, and to discard events smaller than E LLD2 The detection energy is guaranteed not to reduce the data quality of the system.

[0088] In this embodiment, by obtaining different first low energy discrimination thresholds and second low energy discrimination thresholds, the first energy window can be obtained based on the first low energy discrimination threshold, and the second energy window can be obtained based on the second low energy discrimination threshold. In this way, the energy window can be expanded to receive more coincident events, and smaller detection energies can be discarded to limit scattered coincident events, thereby ensuring the accuracy of received true coincident events, thereby improving the accuracy of determined target coincident events and improving the detection efficiency of true coincident events.

[0089] In an exemplary embodiment, detecting a first detection energy satisfying a first energy window and a second detection energy satisfying a second energy window includes:

[0090] Using detection energy greater than a first low energy discrimination threshold as first detection energy;

[0091] The detection energy greater than the second low energy discrimination threshold is used as the second detection energy.

[0092] Exemplarily, the detection energy greater than the first low energy discrimination threshold can be used as the first detection energy that satisfies the first energy window, and the detection energy greater than the second low energy discrimination threshold can be used as the second detection energy that satisfies the second energy window. Further, the target coincidence event can be determined according to the first detection energy and the second detection energy.

[0093] Optionally, the first detection energy and the second detection energy are determined according to the following expression (method):

[0094] E LLD1 >E LLD2

[0095] (E a >E LLD1 ∩E b >E LLD2 )∪(E a >E LLD2 ∩E b >E LLD1 )

[0096] Among them, E LLD1 is the first low energy discrimination threshold, E LLD2 is the second lowest energy discrimination threshold. b >E LLD2 When E a is the first detection energy, E b is the second detection energy; E a >E LLD2 When E b is the first detection energy, E a is the second detection energy.

[0097] In this embodiment, by using the detection energy greater than the first low energy discrimination threshold as the first detection energy and the detection energy greater than the second low energy discrimination threshold as the second detection energy, the first detection energy and the second detection energy can be accurately determined, which can further help to determine the matching events corresponding to the first detection energy and the second detection energy as target matching events, thereby improving the accuracy of the target matching events, determining the target matching events as true matching events, and improving the detection efficiency of true matching events.

[0098] In an exemplary embodiment, Figure 2 As shown, obtaining different first low energy discrimination thresholds and second low energy discrimination thresholds includes S202 to S208, wherein:

[0099] S202, obtaining a different first low energy initial threshold and a second low energy initial threshold, and obtaining a same first low energy standard threshold and a second low energy standard threshold.

[0100] The first low energy initial threshold may be an initial first low energy discrimination threshold, or a first low energy discrimination threshold originally set by a user. The second low energy initial threshold may be an initial second low energy discrimination threshold, or a second low energy discrimination threshold originally set by a user. The first low energy standard threshold and the second low energy standard threshold may be low energy discrimination thresholds contained in a symmetrical energy window.

[0101] Exemplarily, two asymmetric initial energy windows may be determined, and the two initial energy windows respectively include different first low energy initial thresholds and second low energy initial thresholds. The same first low energy standard threshold and second low energy standard threshold may be obtained, for example, the low energy discrimination threshold corresponding to the symmetric energy window may be determined as the same first low energy standard threshold and second low energy standard threshold.

[0102] S204: Acquire an initial coincidence event determined according to the first low energy initial threshold and the second low energy initial threshold.

[0103] The initial coincidence event may be a real coincidence event determined according to different first low energy initial thresholds and second low energy initial thresholds.

[0104] The initial coincidence event can be determined according to the first low energy initial threshold and the second low energy initial threshold. For example, a detector that detects a detection energy greater than the first low energy initial threshold and a detector that detects a detection energy greater than the second low energy initial threshold can be determined, and the coincidence event detected by the above two detectors together is taken as the initial coincidence event.

[0105] S206: Acquire a standard compliance event determined according to the first low energy standard threshold and the second low energy standard threshold.

[0106] The standard coincidence event may be a true coincidence event determined according to a symmetrical energy window.

[0107] Exemplarily, the standard coincidence event can be determined according to the same first low energy standard threshold and second low energy standard threshold in the symmetric energy window; for example, two detectors that detect a low energy discrimination threshold greater than the symmetric energy window can be determined, and the coincidence event detected by the two detectors together is taken as the standard coincidence event. As an example, the PET detector adopts the setting of the symmetric energy window, that is, when the energy detected by the PET detector is greater than the threshold, the coincidence event is received, and the standard coincidence event can be determined according to the following expression:

[0108] E a >E LLD ∩E b >E LLD

[0109] Among them, E LLD are the same first low energy standard threshold and second low energy standard threshold, that is, the low energy discrimination threshold of the symmetric energy window. a >E LLD ∩E b >E LLD In the case of E a The detector and the detection of E b detectors, and the E detected by these two detectors a 、E b The corresponding coincidence event is used as a standard coincidence event, and the standard coincidence event may be a coincidence event of a PET detector generally determined in the prior art.

[0110] S208, adjusting the first low energy initial threshold and the second low energy initial threshold according to the accuracy of the initial conforming event and the standard conforming event to obtain different first low energy discrimination threshold and second low energy discrimination threshold.

[0111] The accuracy of the initial coincidence event can be determined according to the system sensitivity and noise equivalent count rate of the PET detection system.

[0112] Exemplarily, the sensitivity and noise equivalent count rate of the PET detection system can be determined in the case of receiving the initial coincidence event as the accuracy of the initial coincidence event. The sensitivity and noise equivalent count rate of the PET detection system can be determined in the case of receiving the standard coincidence event as the accuracy of the standard coincidence event. Further, the first low energy initial threshold and the second low energy initial threshold can be adjusted according to the accuracy of the initial coincidence event and the accuracy of the initial coincidence event to obtain a target coincidence event with better accuracy. That is, the first low energy initial threshold and the second low energy initial threshold can be adjusted according to the sensitivity and noise equivalent count rate of the PET detection system, so that under the adjusted first low energy discrimination threshold and the second low energy discrimination threshold, the sensitivity and noise equivalent count rate of the PET detection system meet the preset requirements; for example, it can be achieved that compared with receiving the existing standard coincidence event, under different first low energy discrimination threshold and second low energy discrimination threshold settings, the sensitivity of PET detection can be improved while maintaining a good noise equivalent count rate.

[0113] In this embodiment, by determining the initial compliance event determined by the first low energy initial threshold and the second low energy initial threshold, and determining the standard compliance event determined according to the first low energy standard threshold and the second low energy standard threshold, the first low energy initial threshold and the second low energy initial threshold can be adjusted according to the accuracy of the initial compliance event and the standard compliance event to obtain different first low energy discrimination thresholds and second low energy discrimination thresholds, so that the asymmetric energy window can be accurately determined, thereby improving the accuracy of the target compliance event and the detection efficiency of the true compliance event.

[0114] In an exemplary embodiment, obtaining a target coincidence event according to coincidence events detected jointly by the first detector and the second detector includes:

[0115] Acquire a first detector corresponding to the detected first detection energy as a target first detector;

[0116] Acquire a first detection time at which the first detection energy is detected, and determine a second detector at which the second detection energy is detected at a second detection time as a target second detector; the first detection time and the second detection time are times within a preset time window;

[0117] A target coincidence event is obtained according to the coincidence events detected by the target first detector and the target second detector.

[0118] The target first detector may be a detector that detects a first detection energy that satisfies a first energy window. The first detection time may be a time when the target first detector detects the first detection energy. The second detection time may be a time within a preset time window with the first detection time, for example, a time difference between the second detection time and the first detection time is within the preset time window. The target second detector may be a detector that detects the second detection energy at the second detection time.

[0119] Exemplarily, it can be determined that a first detection energy satisfying a first energy window is detected, and a first detection time at which the first detection energy is detected can be obtained. It can be determined whether a second detection energy satisfying a second energy window is detected within a preset time window, and the time at which the second detection energy is detected is the second detection time. It can be determined that a target first detector detects the first detection energy at the first detection time, and it can be determined that a target second detector detects the second detection energy at the second detection time. Furthermore, the detection events of the target first detector and the target second detector within the above-mentioned preset time window can be regarded as target compliance events.

[0120] In this embodiment, a target first detector that detects a first detection energy at a first detection time is obtained, and a target second detector that detects a second detection energy at a second detection time within a preset time window with respect to the first detection time is determined; a target matching event can be obtained based on matching events detected by the target first detector and the target second detector, and the target matching event can be regarded as a true matching event, thereby improving the detection efficiency of true matching events.

[0121] In an exemplary embodiment, Figure 3 As shown, according to the coincidence events detected by the first detector and the second detector, a target coincidence event is obtained, including:

[0122] S302, performing Monte Carlo simulation on a preset simulated detection object to obtain a scattering correction coefficient;

[0123] S304, correcting the coincidence event detected by the first detector and the second detector according to the scatter correction coefficient to obtain a target coincidence event.

[0124] The simulated detection object may be a simulated object for detection in scatter correction. The scatter correction coefficient may be a parameter for scatter correction. The scatter correction may be used to correct scatter coincidence events.

[0125] For example, a Monte Carlo simulation can be performed on a preset simulated detection object according to the detection parameters of the preset PET detector to obtain a scatter correction coefficient. According to the detection parameters of the above PET detector, the object to be detected is detected to obtain a coincidence event, and the scatter correction coefficient can be used to correct the coincidence event detected by the first detector and the second detector to obtain a target coincidence event.

[0126] In this embodiment, a scattering correction coefficient is obtained by performing Monte Carlo simulation on a preset simulated detection object; and based on the scattering correction coefficient, the coincidence events detected by the first detector and the second detector are corrected, so that more accurate target coincidence events can be obtained, thereby further improving the accuracy of target coincidence events and improving the detection efficiency of true coincidence events.

[0127] In an exemplary embodiment, obtaining an asymmetric first energy window and a second energy window includes:

[0128] In response to a trigger instruction of the asymmetric energy window mode, acquiring the asymmetric energy window mode;

[0129] When the imaging mode is an asymmetric energy window mode, an asymmetric first energy window and a second energy window are acquired.

[0130] The asymmetric energy window mode may be a mode that triggers the reference of an asymmetric energy window. The imaging mode may be an imaging mode of a PET system.

[0131] Exemplarily, the asymmetric energy window mode can be used as a special configuration, which can be manually selected by the user to be turned on or adaptively turned on in a specific scanning scenario. The trigger instruction of the asymmetric energy window mode can be an instruction triggered by the user, or can be an instruction triggered adaptively. In response to the trigger instruction of the asymmetric energy window mode, the asymmetric energy window mode is turned on, and when the asymmetric energy window mode is turned on, an asymmetric first energy window and a second energy window are obtained. For example, when the asymmetric energy window mode is turned on, the terminal can determine the high energy discrimination threshold and the low energy discrimination threshold of the first energy window, and the high energy discrimination threshold and the low energy discrimination threshold of the second energy window, wherein the low energy discrimination threshold of the first energy window and the low energy discrimination threshold of the second energy window are different, as the asymmetric first energy window and the second energy window.

[0132] In this embodiment, an asymmetric energy window mode is obtained by responding to a trigger instruction of an asymmetric energy window mode; when the imaging mode is an asymmetric energy window mode, an asymmetric first energy window and a second energy window can be obtained, so that the energy window can be expanded to determine matching events and improve the accuracy of matching events.

[0133] In an exemplary embodiment, a low-activity phantom experiment is conducted in a PET detector with an axial length of 150 cm to observe the counts of true coincidence events, scattered coincidence events, random coincidence events, and the noise equivalent counts of the PET system as a function of the low energy discrimination threshold of the energy window. The results are shown in FIG. Figure 4 shown. Figure 4 As shown in (a), the horizontal axis is LLD and the vertical axis is the number; curve 410 is the count of true coincidence events determined by the standard symmetric energy window, curve 420 is the count of scattered coincidence events determined by the standard symmetric energy window, curve 430 is the count of random coincidence events determined by the standard symmetric energy window, curve 440 is the count of true coincidence events determined by the asymmetric energy window provided by the present application, curve 450 is the count of scattered coincidence events determined by the asymmetric energy window provided by the present application, and curve 460 is the count of random coincidence events determined by the asymmetric energy window provided by the present application, as follows Figure 4 As shown in (a), the coincidence event determination provided by the present application can significantly reduce the introduction of scattered coincidence events and random coincidence events when the system reduces the LLD (low-level discriminator) and try to avoid reducing the real coincidence events, thereby maintaining a higher NEC (Noise equivalent count). Figure 4As shown in (b), the horizontal axis is LLD and the vertical axis is NEC; curve 470 is the NEC corresponding to the standard symmetric energy window, and curve 480 is the NEC corresponding to the asymmetric energy window provided by the present application. Using the standard symmetric energy window solution, even if the LLD is reduced to 200keV, the true coincidence events of the PET system can increase by 59.2%, but the NEC will decrease by 11.4%. Using the coincidence event determination method provided by the present application, in E LLD1 =430keV, E LLD2 =200keV, the sensitivity of the PET system increased by 52.4% and the NEC increased by 1.1%.

[0134] In an exemplary embodiment, to verify that Monte Carlo scatter correction can handle the asymmetric energy window provided by the present application in accordance with the event determination method, a scatter correction pressure test phantom is designed, such as Figure 5 The central lung area of ​​the phantom was perfused with a high-activity liquid source with a contrast ratio of 50:1 to the background. Figure 5 In (a), the six hot balls in the original scatter correction pressure test phantom are replaced with four passive cold balls of different densities, namely 37 mm air ball 510, 37 mm water ball 520, 28 mm salt water ball 530, and 28 mm water ball 540. Experiments are conducted to analyze whether Monte Carlo scatter correction can handle multiple scattering events caused by the expanded asymmetric energy window. Figure 5 As shown in (b), on the basis of normal scanning, a water bag is wrapped outside the phantom to increase the proportion of scattering events and increase the difficulty of scattering correction.

[0135] The results are as follows Figure 6 As shown, Monte Carlo scattering correction can handle the multiple scattering events caused by the expanded asymmetric energy window in accordance with the event determination method proposed in this application. Figure 6 (a) and (b) correspond to Figure 5 (a) and (b) show two scanning scenes.

[0136] In some specific embodiments, the matching event determination method provided by the present application can expand the energy window while discarding matching events with lower energy. The implementation scheme can implement this logic directly by hardware, or it can discard matching events with lower energy offline after generally expanding the energy window and sampling.

[0137] In an exemplary embodiment, Figure 7 As shown, a PET imaging method is provided, which includes: S702 to S706.

[0138] S702, obtaining a target matching event of the object to be detected, where the target matching event is obtained according to the matching event determination method described above;

[0139] S704, determining target imaging data of the object to be detected according to the target matching event;

[0140] S706, performing image reconstruction based on the target imaging data to obtain a target image of the object to be detected.

[0141] The target coincidence event may be a coincidence event obtained according to the above coincidence event determination method. The target imaging data may be data used for PET imaging. The target image may be an image of the object to be detected imaged by a PET system.

[0142] Exemplarily, the target coincidence event of the object to be detected can be obtained according to the above-mentioned coincidence event determination method, and the target imaging data of the object to be detected can be determined according to the target coincidence event. The target imaging data can further be used to reconstruct PET images to obtain the target image of the object to be detected imaged by the PET system.

[0143] In this embodiment, the target coincidence event of the object to be detected is obtained according to the above-mentioned coincidence event determination method; the target imaging data of the object to be detected is determined according to the target coincidence event; image reconstruction is performed based on the target imaging data to obtain the target image of the object to be detected. In this way, PET imaging is performed by accurately determining the target coincidence event, thereby improving the accuracy of PET imaging and improving the image quality of PET imaging.

[0144] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0145] Based on the same inventive concept, the embodiment of the present application also provides a conforming event determination device for implementing the conforming event determination method involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more conforming event determination device embodiments provided below can refer to the limitations of the conforming event determination method above, and will not be repeated here.

[0146] In an exemplary embodiment, Figure 8As shown, a coincidence event determination device is provided, comprising: an energy window acquisition module 810, a detector determination module 820 and a coincidence event determination module 830, wherein:

[0147] The energy window acquisition module 810 is used to acquire an asymmetric first energy window and a second energy window.

[0148] The detector determination module 820 is used to determine the first detector that detected the first detection energy and the second detector that detected the second detection energy when the first detection energy that meets the first energy window and the second detection energy that meets the second energy window are detected.

[0149] The matching event determination module 830 is used to obtain a target matching event according to the matching events detected by the first detector and the second detector.

[0150] In an exemplary embodiment, the first energy window includes a first low energy discrimination threshold, and the second energy window includes a second low energy discrimination threshold. The energy window acquisition module includes a low energy discrimination threshold unit, a first energy window unit, and a second energy window unit.

[0151] The low energy discrimination threshold unit is used to obtain different first low energy discrimination threshold and second low energy discrimination threshold. The first energy window unit is used to obtain a first energy window based on the first low energy discrimination threshold. The second energy window unit is used to obtain a second energy window based on the second low energy discrimination threshold.

[0152] In an exemplary embodiment, the detector determination module includes a first detection energy unit and a second detection energy unit.

[0153] The first detection energy unit is used to use the detection energy greater than the first low energy discrimination threshold as the first detection energy. The second detection energy unit is used to use the detection energy greater than the second low energy discrimination threshold as the second detection energy.

[0154] In an exemplary embodiment, the low energy discrimination threshold unit includes an initial threshold acquisition unit, an initial coincidence event acquisition unit, a standard coincidence event acquisition unit and a threshold adjustment unit.

[0155] The initial threshold acquisition unit is used to acquire different first low energy initial thresholds and second low energy initial thresholds, and acquire the same first low energy standard threshold and second low energy standard threshold. The initial compliance event acquisition unit is used to acquire the initial compliance event determined according to the first low energy initial threshold and the second low energy initial threshold. The standard compliance event acquisition unit is used to acquire the standard compliance event determined according to the first low energy standard threshold and the second low energy standard threshold. The threshold adjustment unit is used to adjust the first low energy initial threshold and the second low energy initial threshold according to the accuracy of the initial compliance event and the standard compliance event, so as to obtain different first low energy discrimination thresholds and second low energy discrimination thresholds.

[0156] In an exemplary embodiment, the coincidence event determination module includes a target first detector unit, a target second detector unit, and a target coincidence event unit.

[0157] The target first detector unit is used to obtain a first detector corresponding to the first detection energy as the target first detector. The target second detector unit is used to obtain a first detection time when the first detection energy is detected, and determine a second detector that detects the second detection energy at the second detection time as the target second detector; the first detection time and the second detection time are times within a preset time window. The target coincidence event unit is used to obtain a target coincidence event based on coincidence events detected by the target first detector and the target second detector.

[0158] In an exemplary embodiment, the coincidence event determination module includes a scatter correction coefficient determination unit and a target coincidence event determination unit.

[0159] The scatter correction coefficient determination unit is used to perform Monte Carlo simulation on the preset simulated detection object to obtain the scatter correction coefficient. The target coincidence event determination unit is used to correct the coincidence event detected by the first detector and the second detector according to the scatter correction coefficient to obtain the target coincidence event.

[0160] In an exemplary embodiment, the energy window acquisition module includes an asymmetric energy window pattern determination unit and an energy window determination unit.

[0161] The asymmetric energy window mode determination unit is used to obtain the asymmetric energy window mode in response to the trigger instruction of the asymmetric energy window mode. The energy window determination unit is used to obtain the asymmetric first energy window and the second energy window when the imaging mode is the asymmetric energy window mode.

[0162] Based on the same inventive concept, the embodiment of the present application also provides a PET imaging device for implementing the PET imaging method involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more PET imaging device embodiments provided below can refer to the limitations on the PET imaging method above, and will not be repeated here.

[0163] In an exemplary embodiment, a PET imaging device is provided, comprising: a target coincidence event acquisition module, a target imaging data determination module and a target image determination module, wherein:

[0164] A target matching event acquisition module is used to acquire a target matching event of the object to be detected, and the target matching event is obtained according to the matching event determination method described above;

[0165] A target imaging data determination module is used to determine the target imaging data of the object to be detected according to the target coincidence event;

[0166] The target image determination module is used to perform image reconstruction based on the target imaging data to obtain a target image of the object to be detected.

[0167] Each module in the above-mentioned coincidence event determination device and PET imaging device can be implemented in whole or in part by software, hardware and a combination thereof. Each module can be embedded in or independent of the processor in the controller in the form of hardware, or can be stored in the memory in the controller in the form of software, so that the processor can call and execute the corresponding operations of each module.

[0168] In an exemplary embodiment, a controller is provided. The controller may be a terminal, and its internal structure diagram may be as shown in FIG. Fig. 9As shown. The controller includes a processor, a memory, an input / output interface, a communication interface, a display unit and an input device. Among them, the processor, the memory and the input / output interface are connected through a system bus, and the communication interface, the display unit and the input device are connected to the system bus through the input / output interface. Among them, the processor of the controller is used to provide computing and control capabilities. The memory of the controller includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the controller is used to exchange information between the processor and an external device. The communication interface of the controller is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be implemented through WIFI, a mobile cellular network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a method for determining a compliance event and a PET imaging method are implemented. The display unit of the controller is used to form a visually visible picture, which can be a display screen, a projection device or a virtual reality imaging device. The display screen can be a liquid crystal display screen or an electronic ink display screen, and the input device of the controller can be a touch layer covering the display screen, or a button, trackball or touchpad set on the controller housing, or an external keyboard, touchpad or mouse.

[0169] Those skilled in the art will understand that Fig. 9 The structure shown in the figure is merely a block diagram of a partial structure related to the scheme of the present application, and does not constitute a limitation on the controller to which the scheme of the present application is applied. The specific controller may include more or fewer components than shown in the figure, or combine certain components, or have a different arrangement of components.

[0170] In one embodiment, a controller is further provided, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above-mentioned method embodiments when executing the computer program.

[0171] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.

[0172] In one embodiment, a computer program product is provided, including a computer program, which implements the steps in the above method embodiments when executed by a processor.

[0173] 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, stored data, displayed data, 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 relevant data must comply with relevant regulations.

[0174] 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 the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in 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 memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive 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. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited to this.

[0175] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, 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.

[0176] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for determining a compliance event, characterized in that: The method comprises: Acquire an asymmetric first energy window and a second energy window; In case of detecting a first detection energy satisfying the first energy window and a second detection energy satisfying the second energy window, determining a first detector that detected the first detection energy and a second detector that detected the second detection energy; A target coincidence event is obtained according to the coincidence event detected jointly by the first detector and the second detector.

2. The method according to claim 1, characterized in that The first energy window includes a first low energy discrimination threshold; The second energy window includes a second low energy discrimination threshold; The step of obtaining the asymmetric first energy window and the second energy window comprises: Acquire different first low energy discrimination threshold and second low energy discrimination threshold; Based on the first low energy discrimination threshold, obtaining the first energy window; The second energy window is obtained according to the second low energy discrimination threshold.

3. The method according to claim 2, characterized in that Detecting a first detection energy satisfying the first energy window and a second detection energy satisfying the second energy window comprises: Using the detection energy greater than the first low energy discrimination threshold as the first detection energy; The detection energy that is greater than the second low energy discrimination threshold is used as the second detection energy.

4. The method according to claim 2, characterized in that: The obtaining of different first low energy discrimination threshold and second low energy discrimination threshold comprises: Acquire a different first low energy initial threshold and a second low energy initial threshold, and acquire a same first low energy standard threshold and a second low energy standard threshold; Acquire an initial coincidence event determined according to the first low energy initial threshold and the second low energy initial threshold; Acquire a standard compliance event determined according to the first low energy standard threshold and the second low energy standard threshold; According to the accuracy of the initial compliance event and the standard compliance event, the first low energy initial threshold and the second low energy initial threshold are adjusted to obtain different first low energy discrimination threshold and second low energy discrimination threshold.

5. The method according to claim 1, characterized in that The step of obtaining a target matching event according to the matching event detected jointly by the first detector and the second detector includes: Acquire a first detector that detects the first detection energy as a target first detector; Acquire a first detection time when the first detection energy is detected, and determine a second detector that detects the second detection energy at a second detection time as a target second detector; the first detection time and the second detection time are times within a preset time window; The target coincidence event is obtained according to the coincidence events detected by the first target detector and the second target detector.

6. The method according to any one of claims 1 to 5, characterized in that The step of obtaining a target matching event according to the matching event detected jointly by the first detector and the second detector includes: Performing Monte Carlo simulation on a preset simulated test object to obtain a scattering correction coefficient; The coincidence event detected by the first detector and the second detector is corrected according to the scatter correction coefficient to obtain the target coincidence event.

7. The method according to any one of claims 1 to 5, characterized in that The step of obtaining the asymmetric first energy window and the second energy window comprises: In response to a trigger instruction of an asymmetric energy window mode, acquiring the asymmetric energy window mode; When the imaging mode is the asymmetric energy window mode, an asymmetric first energy window and a second energy window are acquired.

8. A PET imaging method, characterized in that: The method comprises: Acquire a target conforming event of the object to be detected, wherein the target conforming event is obtained according to the conforming event determination method according to any one of claims 1 to 7; Determining target imaging data of the object to be detected according to the target coincidence event; Image reconstruction is performed based on the target imaging data to obtain a target image of the object to be detected.

9. A device for determining a coincidence event, characterized in that: The device comprises: An energy window acquisition module, used for acquiring an asymmetric first energy window and a second energy window; a detector determination module, configured to, upon detecting a first detection energy satisfying the first energy window and a second detection energy satisfying the second energy window, determine a first detector that has detected the first detection energy and a second detector that has detected the second detection energy; The conforming event determining module is used to obtain a target conforming event according to the conforming events detected jointly by the first detector and the second detector.

10. A controller, comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 8 are implemented.

Images