Time difference determination method, imaging method and positron emission tomography system

Abstract

The application relates to a time difference determination method, an imaging method and a positron emission tomography system. The method is applied to the positron emission tomography system. The positron emission tomography system comprises at least two corresponding detection modules. Each detection module comprises a silicon photomultiplier array, and the silicon photomultiplier array comprises at least two silicon photomultiplier units. The method comprises: for each detection module, acquiring a photon signal received by each silicon photomultiplier unit in the detection module; the photon signal comprises time information; and determining a target time difference between a photon signal pair received by the corresponding detection module according to the time information in all the photon signals. The time difference determination method provided by the application can reduce the target time difference between the photon signal pair, so that the time resolution can be optimized.

Description

Technical Field

[0001] This application relates to the field of imaging technology, and in particular to a time difference determination method, an imaging method, and a positron emission tomography (PET) system. Background Technology

[0002] With the development of imaging technology, time-of-flight positron emission tomography (TOF-PET) has become a widely used PET imaging technology in clinical practice due to its advantages such as high imaging quality and wide applicability.

[0003] Temporal resolution is one of the key performance indicators of Time-of-Flight (TOF) PET. In long-scintillation crystals, the distance photons travel within the crystal is related to the interaction depth, leading to differences in the time it takes for photons to reach the photodetector—a phenomenon known as the Depth of Interaction (DOI) effect in TOF, which reduces temporal resolution. Therefore, there is a pressing need to provide a method to reduce the time difference between photons reaching the photodetector, thereby optimizing temporal resolution. Summary of the Invention

[0004] Therefore, it is necessary to provide a time difference determination method, imaging method, and positron emission tomography system that can reduce the time difference between photons reaching the photoelectric sensor to optimize time resolution, thereby addressing the aforementioned technical problems.

[0005] In a first aspect, this application provides a time difference determination method applied to a positron emission tomography (PET) imaging system. The PET imaging system includes at least two corresponding detection modules, each detection module including a silicon photomultiplier tube array, the silicon photomultiplier tube array including at least two silicon photomultiplier tube units. The method includes:

[0006] For each detection module, the photon signal received by each silicon photomultiplier tube unit in the detection module is acquired; the photon signal includes time information;

[0007] Based on the time information in all photon signals, determine the target time difference between the photon signal pairs received by the corresponding detection modules.

[0008] In one embodiment, determining the target time difference of the photon signal pair received by the corresponding detection module based on the time information in all photon signals includes:

[0009] For each detection module, a first initial time difference is determined based on the time information of the photon signal corresponding to the detection module;

[0010] The target time difference is determined based on the first initial time difference of all photon signals.

[0011] In one embodiment, determining the target time difference of the photon signal pair received by the corresponding detection module based on the time information in all photon signals includes:

[0012] Based on the timing information in all photon signals, determine the second initial time difference of at least two photon signal pairs;

[0013] Select an intermediate time difference from the second initial time differences of at least two photon signal pairs, and optimize the intermediate time difference based on the other second initial time differences from the second initial time differences of at least two photon signal pairs, except for the intermediate time difference, to obtain the target time difference.

[0014] In one embodiment, determining the target time difference between photon signal pairs received by the corresponding detection module based on the time information in all photon signals includes:

[0015] The time information from all photon signals is input into a pre-trained time reconstruction model to obtain the target time difference.

[0016] In one embodiment, the photon signal includes energy information; the time information from all photon signals is input into a pre-trained time reconstruction model to obtain the target time difference, including:

[0017] The time and energy information from all photon signals are input into the time reconstruction model to obtain the target time difference.

[0018] Secondly, one embodiment of this application provides an imaging method, the method comprising:

[0019] Acquire photon signals and determine photon signal pairs based on the photon signals;

[0020] The response line is determined based on the photon signal pairs, and the position information of the annihilation event on the response line is determined based on the target time difference between the photon signal pairs; the target time difference between the photon signal pairs is determined according to the method provided in the first aspect above;

[0021] Image reconstruction is performed based on response lines and location information to obtain positron emission tomography (PET) images.

[0022] Thirdly, one embodiment of this application provides a positron emission tomography (PET) imaging system, including at least two corresponding detection modules and a signal processing module. Each detection module includes a silicon photomultiplier tube array, and the silicon photomultiplier tube array includes at least two silicon photomultiplier tube units. The signal processing module is connected to the detection module.

[0023] The signal processing module is used to acquire the photon signal received by each silicon photomultiplier tube unit in the detection module, and determine the target time difference between the photon signal pairs received by the corresponding detection module based on the time information in all the received photon signals.

[0024] In one embodiment, the detection module further includes at least one crystal, and for each crystal, a dual-end readout design is adopted. A silicon photomultiplier array is provided on the side of each crystal away from the imaging object, and any one of a silicon photomultiplier array, a silicon photomultiplier tube, and a photon detector is provided on the side of the crystal close to the imaging object.

[0025] In one embodiment, the crystal includes a first crystal and a second crystal, with a reflective film disposed between the first crystal and the second crystal.

[0026] Fourthly, one embodiment of this application provides a time difference determination device applied to a positron emission tomography (PET) system. The PET system includes at least two corresponding detection modules, each detection module including a silicon photomultiplier tube array, the silicon photomultiplier tube array including at least two silicon photomultiplier tube units. The device includes:

[0027] The acquisition module is used to acquire the photon signal received by each silicon photomultiplier tube unit in each detection module; the photon signal includes time information.

[0028] The determination module is used to determine the target time difference between photon signal pairs received by the corresponding detection module based on the time information in all photon signals.

[0029] Fifthly, one embodiment of this application provides an imaging apparatus, the apparatus comprising:

[0030] The acquisition module is used to acquire photon signals and determine photon signal pairs based on the photon signals;

[0031] The determination module is used to determine the response line based on the photon signal pair and to determine the position information of the annihilation event on the response line based on the target time difference between the photon signal pairs; the target time difference between the photon signal pairs is determined based on the time difference determination device provided in the fourth aspect above.

[0032] The reconstruction module is used to reconstruct the image based on the response lines and location information to obtain positron emission tomography (PET) images.

[0033] Sixthly, this application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the methods provided in the first or second aspect above.

[0034] In a seventh aspect, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method provided in the first or second aspect above.

[0035] Eighthly, this application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the methods provided in the first or second aspect above.

[0036] The aforementioned time difference determination method, imaging method, and positron emission tomography (PET) system are described above. This method is applied to a PET system. The PET system includes at least two corresponding detection modules, each detection module including a silicon photomultiplier tube (SiP) array, and the SiP array including at least two SiP units. The method includes, for each detection module, acquiring the photon signal received by each SiP unit in the detection module; the photon signal includes time information; and determining the target time difference between photon signal pairs received by the corresponding detection module based on the time information in all photon signals. Compared to conventional techniques that determine the time difference using photon signals received by a single SiP in the detection module, in this embodiment, the target time difference between photon signal pairs determined by the time information included in the photon signals received by each SiP unit in the detection module is smaller, enabling precise time positioning of photon deposition within the crystal, thereby optimizing temporal resolution. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the structure of a positron emission tomography (PET) system in one embodiment.

[0039] Figure 2 This is a schematic diagram of the detection module in one embodiment;

[0040] Figure 3 This is a schematic diagram of the detection module in another embodiment;

[0041] Figure 4 This is a flowchart illustrating the steps of a time difference determination method in one embodiment;

[0042] Figure 5 This is a flowchart illustrating the steps of a time difference determination method in another embodiment;

[0043] Figure 6 This is a flowchart illustrating the steps of a time difference determination method in another embodiment;

[0044] Figure 7 This is a flowchart illustrating the steps of a time difference determination method in another embodiment;

[0045] Figure 8 This is a schematic diagram of the target time difference and event count obtained from simulation in one embodiment;

[0046] Figure 9 This is a schematic diagram of the steps of an imaging method in one embodiment;

[0047] Figure 10 This is a schematic diagram of the detection module structure in another embodiment;

[0048] Figure 11 This is a schematic diagram of the detection module structure in another embodiment;

[0049] Figure 12 This is a schematic diagram of the detection module structure in another embodiment;

[0050] Figure 13 This is a schematic diagram of the time difference determination device in one embodiment;

[0051] Figure 14 This is a schematic diagram of the imaging device in one embodiment;

[0052] Figure 15 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0054] It should be noted that the terms "first," "second," etc., used in this application may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from the second element. The terms "comprising" and "having," and any variations thereof, used in this application, are intended to cover non-exclusive inclusion. The term "at least one" used in this application refers to one or more.

[0055] Before introducing the technical solutions of the embodiments disclosed in this application, the background technology or research context on which the embodiments of this application are based will be introduced first. With the development of imaging technology, Time-of-Flight Positron Emission Tomography (TOF-PET) has become a widely used PET imaging technology in clinical practice due to its advantages such as high imaging quality and wide applicability. Temporal resolution is one of the important indicators of TOF-PET. The temporal resolution of commercial TOF-PET is 180 ps, ​​and laboratory time resolution can reach the level of 100 ps. The TOF-PET imaging system includes a detection module, which includes a crystal and a photoelectric sensor. Since the distance that photons travel in the crystal is related to the interaction depth, this will cause differences in the time detected by the photoelectric sensor, that is, the depth of interaction (DOI) effect of TOF, thereby reducing the temporal resolution. In other words, different photon deposition depths will lead to different time series generated in the photoelectric sensor. The deposition point is closer to the photoelectric sensor, and the initial photon time distribution is more concentrated. The further away the deposition point is from the photoelectric sensor, the more diffuse the initial photon time distribution is. Therefore, there is an urgent need to provide a method to reduce the time difference between photons reaching the photoelectric sensor in order to optimize the temporal resolution.

[0056] The time difference determination method provided in this application embodiment is applied to, for example, Figure 1 The positron emission tomography (PET) system shown includes at least two corresponding detection modules 11 and signal processing modules 12, with each detection module 11 connected to the signal processing module 12. The structure of the detection module 11 is as follows: Figure 2 and Figure 3 As shown, the detection module 11 includes a crystal 111 (scintillation crystal array) and a photodetector 112 attached to the crystal. The photodetector 112 may be a micro silicon photomultiplier array (uSiPM), which includes at least two silicon photomultiplier units 1120. Figure 2 and Figure 3 In the middle, the part located inside crystal 111 is the one that enters crystal 111. Photon, represented by dashed line The scintillation light generated by the photons (511 keV) enters the path of each silicon photomultiplier tube unit 1120. During TOF-PET imaging, when... After photons enter the crystal, they generate scintillation light through the photoelectric effect or Compton scattering, and then enter the photodetector 112; the photodetector 112 converts the scintillation light into an electrical signal. The signal processing module 12 receives the electrical signal from each silicon photomultiplier tube unit 1120 in the photodetector 112. For example... Figure 2 shown, if After photons enter the crystal, they are deposited on the side furthest from the photodetector 112. The time it takes for the scintillation light generated by the photons to reach each silicon photomultiplier tube unit 1120 in the silicon photomultiplier tube array is different and relatively long. Figure 3 As shown, if After the photons enter the crystal, they are deposited on the side near the photodetector 112. The time it takes for the scintillation light generated by the photons to reach each silicon photomultiplier tube unit 1120 in the silicon photomultiplier tube array is different and relatively short.

[0057] In an optional embodiment, the 3mm*3mm*20mm crystal can correspond to a 2*2 silicon photomultiplier tube unit, or it can correspond to a 3*3 or 4*4 silicon photomultiplier tube unit.

[0058] The technical solution of this application and how the technical solution of this application solves the technical problem are described in detail below with specific embodiments.

[0059] In one embodiment, such as Figure 4 As shown, a time difference determination method is provided, which can be applied to, for example... Figure 1 The signal processing module of the positron emission tomography (PET) system shown is used as an example for illustration. In this embodiment, the method includes the following steps:

[0060] Step 400: For each detection module, acquire the photon signal received by each silicon photomultiplier tube unit in the detection module; the photon signal includes time information.

[0061] The silicon photomultiplier tube array in the detection module of a positron emission tomography (PET) system comprises multiple silicon photomultiplier tube units. Each silicon photomultiplier tube unit receives scintillation light generated by the crystal adjacent to it and converts the received scintillation light into an electrical signal, thus acquiring the photon signal received by each silicon photomultiplier tube unit. This photon signal includes time information, which can be the time when each silicon photomultiplier tube unit receives the photon signal, or the time difference between the time of any photon signal received by all acquired photon signal times from all silicon photomultiplier tube units and the time of other photon signals. Specifically, any photon signal is the photon signal corresponding to the shortest time among all the photon signal times received by all silicon photomultiplier tube units.

[0062] In an optional embodiment, such as Figure 2 and Figure 3 As shown, time information can include T1, T2, and T3, or the difference between T3 and T1 and the difference between T2 and T1. From Figure 2 and Figure 3As can be seen, the photon deposition location in the crystal is far from the silicon photomultiplier tube array, with a large time difference, while the photon deposition location in the crystal is close to the silicon photomultiplier tube array, with a small time difference.

[0063] Step 410: Determine the target time difference between photon signal pairs received by the corresponding detection modules based on the time information in all photon signals.

[0064] After receiving the photon signals from all the silicon photomultiplier tube units, the signal processing module determines the target time difference between photon signal pairs received by the corresponding detection modules based on the timing information of all photon signals. In essence, after obtaining the timing information of all photon signals, the signal processing module identifies the photon signal pairs among them and determines the target time difference between these pairs based on their timing information. A photon signal pair is an annihilation photon signal received by two corresponding detection modules. This embodiment does not limit the specific method used to determine the target time difference between photon signal pairs received by the corresponding detection modules based on the timing information of all photon signals, as long as the function is achieved.

[0065] This application provides a time difference determination method applied to a positron emission tomography (PET) system. The PET system includes at least two corresponding detection modules, each including a silicon photomultiplier tube (SPT) array, and the SPT array including at least two SPT units. The method includes, for each detection module, acquiring the photon signal received by each SPT unit in the detection module; the photon signal includes time information; and determining the target time difference between photon signal pairs received by the corresponding detection module based on the time information in all photon signals. Compared to conventional techniques that determine the time difference using the photon signal received by a single SPT in the detection module, in this embodiment, the target time difference between photon signal pairs determined by the time information included in the photon signal received by each SPT unit in the detection module is smaller, enabling precise time positioning of photon deposition within the crystal, thereby optimizing temporal resolution.

[0066] In one embodiment, such as Figure 5 As shown, this involves determining the target time difference of a photon signal pair received by a corresponding detection module based on the time information in all photon signals. The steps of this implementation include:

[0067] Step 500: For each detection module, determine the first initial time difference based on the time information of the photon signal corresponding to the detection module.

[0068] For each detection module, after receiving the time information of the photon signals received by all silicon photomultiplier tube units within that detection module, the signal processing module determines a first initial time difference based on the time information of the photon signals corresponding to that detection module. It can be understood that the time information included in the photon signals encompasses the time when each silicon photomultiplier tube unit receives its photon signal. The signal processing module selects an intermediate time from the multiple photon signal times and calculates the difference between the times of the other photon signals and the intermediate time to obtain the first initial time difference. The intermediate time is the minimum time among the multiple photon signal times.

[0069] Step 510: Determine the target time difference based on the first initial time difference of all photon signals.

[0070] After obtaining the first initial time difference of all photon signals, the signal processing module determines the photon signal pairs among all photon signals, and determines the target time difference based on the first initial time difference of the photon signals in the photon signal pairs.

[0071] In one optional embodiment, a method is provided for determining the target time difference between pairs of photon signals received by a corresponding detection module based on time information in all photon signals. The specific details of this method include:

[0072] For the same annihilation event, two detection modules (denoted as module one and module two) are used:

[0073] Step a: Obtain the photon arrival timestamps of all silicon photomultiplier tube units in both modules respectively:

[0074] The first module's timestamp set is: {t1, t2, ..., t} n}

[0075] The second module's timestamp set: {t'1, t'2 ..., t' m} ;

[0076] Step b: Calculate the first initial time difference sequence within each module:

[0077] First module sequence: Δt_i = t_i - min(t1, t2, ..., t) n )

[0078] Second module sequence: Δt'_j = t'_j - min(t'1, t'2, ..., t' m ) ;

[0079] Step c: Construct a joint feature vector based on the first initial time difference sequences of the two modules, and input the fitting function:

[0080] Input: V = [Δt1...Δt] n ,Δt'1...Δt' m ]

[0081] Fitting function: ΔT_target = F(V)

[0082] Where F is achieved in any of the following ways:

[0083] ① Linear weighting:

[0084] ② Machine learning models (such as neural networks).

[0085] In an optional embodiment, after the initial time difference of all photon signals, the signal processing module performs fitting processing on the initial time difference corresponding to each detection module to obtain a fitted time difference; and determines the target time difference based on the fitted time difference of the corresponding detection module, that is, calculates the difference between the fitted time differences of the corresponding detection modules to obtain the target time difference.

[0086] In this embodiment, for each detection module, a first initial time difference is determined based on the time information of the photon signal corresponding to the detection module; and a target time difference is determined based on the first initial time difference of all photon signals. This method of determining the target time difference is quick and easy to implement, which can improve the efficiency of determining the time difference and make the time difference determination method more practical.

[0087] In an optional embodiment, such as Figure 6 As shown, this involves determining the target time difference of a photon signal pair received by a corresponding detection module based on the time information in all photon signals. The steps of this implementation include:

[0088] Step 600: Determine the second initial time difference of at least two photon signal pairs based on the time information in all photon signals.

[0089] The positron emission tomography (PET) system includes at least two corresponding detection modules, and the silicon photomultiplier tube array includes at least two silicon photomultiplier tube units. Therefore, the photon signals acquired by the signal processing module include at least two photon signal pairs. Based on the time information of each photon signal pair, a second initial time difference between the photon signal pairs is determined.

[0090] Step 610: Select an intermediate time difference from the second initial time differences of at least two photon signal pairs, and optimize the intermediate time difference based on the other second initial time differences of the at least two photon signal pairs excluding the intermediate time difference, to obtain the target time difference.

[0091] After determining the second initial time difference of at least two photon signal pairs, the signal processing module selects one of the second initial time differences as an intermediate time difference; this can be either the smallest of the at least two second initial time differences or a randomly selected time difference. After determining the intermediate time difference, the signal processing module optimizes the intermediate time difference using the other second initial time differences from the at least two photon signal pairs, excluding the intermediate time difference, to obtain the final target time difference.

[0092] Specifically, for the same annihilation event, there are two detection modules (denoted as the first module and the second module):

[0093] Step a: Obtain the photon arrival timestamps of all silicon photomultiplier tube units in both modules respectively:

[0094] The first module's timestamp set is: {t1, t2, ..., t} n}

[0095] The second module's timestamp set: {t'1, t'2, ..., t' m} ;

[0096] Step b: Calculate the second initial time difference sequence: {t1-t'1, t2-t'2, ..., t n - t' m};

[0097] Step c: Select the intermediate time difference: t1-t'1;

[0098] Step d: Based on t2-t'2, ..., t n - t' m Optimize t1-t'1 to obtain the target time difference.

[0099] The specific optimization methods can be mean correction, weighted mean optimization, iterative convergence optimization, etc. This embodiment does not limit these methods, as long as they can achieve the desired function.

[0100] In this embodiment, a second initial time difference between at least two photon signal pairs is first determined based on the time information in all photon signals. Then, an intermediate time difference is selected from the second initial time differences of the at least two photon signal pairs. Based on the other second initial time differences of the at least two photon signal pairs excluding the intermediate time difference, the intermediate time difference is optimized to obtain the target time difference between the photon signal pairs received by the corresponding detection module. This method of determining the target time difference is quick and easy to implement, which can improve the efficiency of determining the time difference and make the time difference determination method more practical.

[0101] In one embodiment, an implementation method involves determining the target time difference between photon signal pairs received by corresponding detection modules based on time information in all photon signals. This implementation method includes:

[0102] The time information from all photon signals is input into a pre-trained time reconstruction model to obtain the target time difference.

[0103] The signal processing module stores a pre-trained temporal reconstruction model. The temporal reconstruction model can be any of the following: a convolutional neural network model, a network model based on a self-attention mechanism, a generative model, etc.

[0104] After acquiring the time information from all photon signals in the signal processing module, the time information from all photon signals is input into a pre-trained time reconstruction model. By reconstructing the time using the time reconstruction model, the target time difference can be obtained.

[0105] In an optional embodiment, the training method for the time reconstruction model includes: acquiring training samples; and training an initial network model based on the training samples to obtain the time reconstruction model. The training samples include time information samples of photon signals and the corresponding gold standard.

[0106] In this embodiment, the time information in all photon signals is directly input into a pre-trained time reconstruction model to obtain the target time difference. This improves the efficiency of determining the target time difference and makes the time difference determination method more practical.

[0107] In one embodiment, the photon signal includes energy information. After receiving the photon signal from the photodetector, the signal processing module determines the energy information of the photon signal based on its amplitude. In this case, another implementation involves inputting the time information from all photon signals into a pre-trained time reconstruction model to obtain the target time difference. This implementation includes:

[0108] The time and energy information from all photon signals are input into the time reconstruction model to obtain the target time difference.

[0109] When the photon signal includes both time and energy information, the signal processing module inputs both time and energy information from all photon signals into the time reconstruction model. The time reconstruction model is then used to reconstruct the time and obtain the target time difference.

[0110] In an optional embodiment, the training method for the time reconstruction model includes: acquiring training samples; training an initial neural network based on the training samples to obtain the time reconstruction model. The training samples include time information samples and energy information samples of photon signals, as well as the corresponding gold standard.

[0111] In this embodiment, the photon signal also includes energy information. The time information and energy information in the photon signal are both input into the time reconstruction model to obtain the target time difference. In this way, the time reconstruction module obtains more information, which can improve the accuracy of the target time difference output by the time reconstruction model, thereby improving the practicality of the time difference determination method.

[0112] Please see Figure 7 One embodiment of this application provides a time difference determination method, which is applied to the above-described... Figure 1 The signal processing module in the positron emission tomography (PET) system shown includes the following steps:

[0113] Step 700: For each detection module, acquire the photon signal received by each silicon photomultiplier tube unit in the detection module; the photon signal includes time information and energy information;

[0114] Step 710: For each detection module, determine the initial time difference based on the time information of the photon signal corresponding to the detection module; determine the initial energy difference based on the energy information of the photon signal corresponding to the detection module.

[0115] Step 720: Input the initial time difference and initial energy difference of all photon signals into the pre-trained time reconstruction model to obtain the target time difference between photon signal pairs.

[0116] In an optional embodiment, the crystal in the detection module is a 3mm*3mm*20mm lutetium yttrium orthosilicate (LYSO) crystal, consisting of nine 1mm silicon photomultiplier tube units. A schematic diagram obtained from simulation using the aforementioned time difference determination method is shown below. Figure 8 As shown. Figure 8 The horizontal axis represents the target time difference, and the vertical axis represents the event count. The simulation yielded a time resolution of 58.45, meaning that the time difference determination method of this application can improve the time resolution from the traditional 95ps level to approximately 60ps.

[0117] Please see Figure 9 This application provides an imaging method in one embodiment, using the application of this method to the signal processing module of a positron emission tomography (PET) system as an example. In this embodiment, the method includes the following steps:

[0118] Step 900: Acquire photon signals and determine photon signal pairs based on the photon signals.

[0119] The signal processing module acquires the photon signal. For a description of how the signal processing module acquires the photon signal, please refer to the detailed description in the above embodiments; it will not be repeated here.

[0120] A positron emission tomography (PET) system includes at least two corresponding detection modules. After acquiring photon signals, the signal processing module identifies photon signal pairs within the photon signals. Essentially, within a set time window, the signal processing module searches for photon signals simultaneously detected by the two corresponding detection modules and identifies them as photon signal pairs.

[0121] Step 910: Determine the response line based on the photon signal pairs, and determine the position information of the annihilation event on the response line based on the target time difference between the photon signal pairs; the target time difference between the photon signal pairs is determined according to the time difference determination method provided in the above embodiment.

[0122] The Line of Response (LOR) is a straight line connecting the centers of the two detection modules where a coincidence event occurs. This line represents the propagation path of the annihilated photon pair. After obtaining the photon signal pair, the signal processing module obtains the LOR by connecting the two detection modules corresponding to the photon signal pair. After determining the target time difference between the photon signal pairs according to the time difference determination method provided in the above embodiments, the signal processing module calculates the distance difference between the annihilation event and the two detection modules based on the target time difference; the position information of the annihilation event on the LOR can be determined based on this distance difference. The method for determining the target time difference between photon signal pairs can be referred to the specific description in the above embodiments, and will not be repeated here.

[0123] Step 920: Reconstruct the image based on the response lines and location information to obtain a positron emission tomography (PET) image.

[0124] After determining the response line and the position information of the annihilation event on that response line, the signal processing module performs image reconstruction using an image reconstruction method to obtain a positron emission tomography (PET) image. It can be understood that the signal processing module determines the projection data based on the response line, i.e., generates a sine wave based on the response line, and then performs image reconstruction based on the sine wave and position information to obtain the PET image. The image reconstruction method can be a filtered back-projection reconstruction method, an iterative reconstruction method, or a TOF-PET reconstruction method. This embodiment does not limit the specific image reconstruction method used, as long as it achieves the desired function.

[0125] In an optional embodiment, the imaging method further includes: after obtaining the positron emission tomography (PET) image, performing post-processing (filtering, quantification, and three-dimensional visualization, etc.) on the PET image.

[0126] The imaging method provided in this application acquires photon signals and determines photon signal pairs based on the photon signals; determines a response line based on the photon signal pairs; and determines the position information of an annihilation event on the response line based on the target time difference between the photon signal pairs. The target event difference between the photon signal pairs is determined according to the method provided in the above embodiment. Image reconstruction is performed based on the response line and the position information to obtain a positron emission tomography (PET) image. In this embodiment, the target time difference between photon signal pairs is determined according to the above time difference determination method. Therefore, this imaging method has all the beneficial effects of the above time difference determination method, that is, the imaging method has a high temporal resolution, thereby improving the quality of the obtained PET image.

[0127] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps. It is understood that the steps in different embodiments can be freely combined as needed, and all non-contradictory solutions formed by such combinations are within the scope of protection of this application.

[0128] In one embodiment, such as Figures 1-3 As shown, one embodiment of this application provides a positron emission tomography (PET) system, including at least two corresponding detection modules 11 and signal processing modules 12. Each detection module 11 includes a silicon photomultiplier tube array, which includes at least two silicon photomultiplier tube units 1120. The signal processing module 12 is connected to the detection module 11. The description of the detection module 11 and the signal processing module 12 can be found in the detailed description of the above embodiment, and will not be repeated here.

[0129] The signal processing module 12 is used to acquire the photon signal received by each silicon photomultiplier tube unit 1120 in the detection module 11, and determine the target time difference between the photon signal pairs received by the corresponding detection module based on the time information in all the received photon signals.

[0130] For a detailed description of the process by which the signal processing module 12 acquires photon signals and determines the target time difference between photon signal pairs based on all photon signals, please refer to the detailed description of the above embodiments, which will not be repeated here.

[0131] The positron emission tomography (PET) system provided in this application includes at least two corresponding detection modules 11 and a signal processing module 12. Each detection module 11 includes a silicon photomultiplier tube array, which includes at least two silicon photomultiplier tube units 1120. The signal processing module 12 is connected to the detection module 11. The signal processing module 12 is used to acquire the photon signal received by each silicon photomultiplier tube unit 1120 in the detection module 11, and determine the target time difference between the photon signal pairs received by the corresponding detection module based on the time information in all the received photon signals. Compared with the conventional technology that determines the time difference by the photon signal received by a single silicon photomultiplier tube in the detection module, in this embodiment, the target time difference between the photon signal pairs determined by the time information included in the photon signal received by each silicon photomultiplier tube unit 1120 in the detection module 11 is smaller, which can accurately locate the deposition of photons in the crystal and thus optimize the time resolution.

[0132] In one embodiment, the detection module 11 further includes at least one crystal 111. For each crystal 111, a dual-end readout design is adopted. A silicon photomultiplier array is provided on the side of each crystal 111 away from the imaging object, and any one of a silicon photomultiplier array, a silicon photomultiplier tube, and a photon detector is provided on the side of the crystal 111 close to the imaging object.

[0133] It is understandable that, such as Figure 10 As shown, the detection module 11 includes a crystal 111. A silicon photomultiplier tube array is disposed on the side of the crystal 111 facing away from the imaging object, and another silicon photomultiplier tube array is disposed on the side of the crystal 111 closer to the imaging object. The silicon photomultiplier tube arrays on both sides of the crystal 111 can be the same or different. Figure 11 As shown, a silicon photomultiplier tube or photon detector 113 is disposed on the side of the crystal 111 closest to the imaging object.

[0134] The detection module 11 may include multiple crystals, i.e., a crystal array. For each crystal 111, a silicon photomultiplier array is provided on the side of the crystal 111 away from the imaging object, and any one of a silicon photomultiplier array, a silicon photomultiplier tube, and a photon detector is provided on the side of the crystal 111 close to the imaging object.

[0135] In this embodiment, the detection module 11 may include multiple crystals 111, which can improve the spatial resolution and spatial positioning accuracy of the positron emission tomography (PET) system, thereby improving the spatial resolution of the PET image. Furthermore, in this embodiment, a silicon photomultiplier tube array is disposed on the side of each crystal 111 facing away from the imaging object, and any one of a silicon photomultiplier tube array, a silicon photomultiplier tube, and a photon detector is disposed on the side of each crystal 111 closest to the imaging object. This allows for the acquisition of photon signals using a dual-end readout method, resulting in more time information in the acquired photon signals and improving the accuracy of the determined target time difference.

[0136] In one embodiment, such as Figure 12 As shown, crystal 111 includes a first crystal 111a and a second crystal 111b, and a reflective film 1110 is disposed between the first crystal 111a and the second crystal 111b.

[0137] It is understood that the crystal 111 in the detection module 11 is composed of a first crystal 111a and a second crystal 111b. A reflective film 1110 is disposed between the first crystal 111a and the second crystal 111b to achieve optical isolation. A silicon photomultiplier array is disposed on the side of the first crystal 111a away from the second crystal 111b, and a silicon photomultiplier array is disposed on the side of the second crystal 111b away from the first crystal 111a. This allows the target time difference to be obtained using a dual-end readout method.

[0138] In an optional embodiment, the first crystal 111a and the second crystal 111b can both be 3mm*3mm*10mm, and the first crystal 111a and the second crystal 111b can be spliced ​​together to form a 3mm*3mm*20mm crystal 111.

[0139] In this embodiment, the crystal 111 includes a first crystal 111a and a second crystal 111b. A reflective film 1110 is disposed between the first crystal 111a and the second crystal 111b. This divides a crystal into two parts, which can reduce the crystal volume and thus reduce the distance between the position where photons are deposited in the crystal 111 and the silicon photomultiplier tube array. This can reduce the target time difference between determined photon signal pairs and thus improve the time resolution.

[0140] Based on the same inventive concept, this application also provides a time difference determination device for implementing the time difference determination method described above, and an imaging device for the imaging method. The solution provided by this device is similar to the solution described in the above method; therefore, the specific limitations in one or more time difference determination devices and imaging devices provided below can be found in the limitations of the time difference determination method and imaging method described above, and will not be repeated here.

[0141] In one embodiment, such as Figure 13 As shown, a time difference determination device is provided, applied to a positron emission tomography (PET) system. The PET system includes at least two corresponding detection modules, each detection module including a silicon photomultiplier tube array, the silicon photomultiplier tube array including at least two silicon photomultiplier tube units. The device includes: an acquisition module 20 and a determination module 21, wherein:

[0142] Acquisition module 20 is used to acquire the photon signal received by each silicon photomultiplier tube unit in each detection module; the photon signal includes time information;

[0143] The determining module 21 is used to determine the target time difference between the photon signal pairs received by the corresponding detection module based on the time information in all photon signals.

[0144] In one embodiment, the determining module 21 is specifically used to determine a first initial time difference for each detection module based on the time information of the photon signal corresponding to the detection module; and to determine a target time difference based on the first initial time difference of all photon signals.

[0145] In one embodiment, the determining module 21 is specifically configured to determine a second initial time difference of at least two photon signal pairs based on the time information in all photon signals; select an intermediate time difference from the second initial time differences of at least two photon signal pairs; optimize the intermediate time difference based on the other second initial time differences of at least two photon signal pairs besides the intermediate time difference; and obtain a target time difference.

[0146] In one embodiment, the determining module 21 is further configured to input the time information in all photon signals into a pre-trained time reconstruction model to obtain the target time difference.

[0147] In one embodiment, the determining module 21 is further configured to input the time information and energy information in all photon signals into the time reconstruction model to obtain the target time difference.

[0148] In one embodiment, such as Figure 14As shown, an imaging device is provided, comprising: an acquisition module 30, a determination module 31, and a reconstruction module 32. Wherein:

[0149] Acquisition module 30 is used to acquire photon signals and determine photon signal pairs based on the photon signals;

[0150] The determining module 31 is used to determine the response line based on the photon signal pair, and to determine the position information of the annihilation event on the response line based on the target time difference between the photon signal pairs; the target time difference between the photon signal pairs is determined according to the time difference determining device provided in the above embodiment;

[0151] The reconstruction module 32 is used to reconstruct the image based on the response line and position information to obtain a positron emission tomography (PET) image.

[0152] The modules in the aforementioned time difference determination device and imaging device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the operations corresponding to each module.

[0153] In one embodiment, a computer device is provided, which may be a signal processing module, and its internal structure diagram may be as follows: Figure 15As shown, the computer device includes a processor, memory, input / output interface, communication interface, display unit, and input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interface. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The input / output interface is used for exchanging information between the processor and external devices. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, Near Field Communication (NFC), or other technologies. When the computer program is executed by the processor, it implements a time difference determination method or an imaging method. The display unit is used to form a visually visible image and can be a display screen, a projection device, or a virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the computer device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads set on the casing of the computer device, or external keyboards, touchpads, or mice, etc.

[0154] Those skilled in the art will understand that Figure 15 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0155] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to perform the following steps:

[0156] For each detection module, the photon signal received by each silicon photomultiplier tube unit in the detection module is acquired; the photon signal includes time information;

[0157] Based on the time information in all photon signals, determine the target time difference between the photon signal pairs received by the corresponding detection modules.

[0158] In one embodiment, when the processor executes the computer program, it further performs the following steps: for each detection module, determining a first initial time difference based on the time information of the photon signal corresponding to the detection module; and determining a target time difference based on the first initial time difference of all photon signals.

[0159] In one embodiment, when the processor executes the computer program, it further performs the following steps: determining a second initial time difference between at least two photon signal pairs based on the time information in all photon signals; selecting an intermediate time difference from the second initial time differences between the at least two photon signal pairs; and optimizing the intermediate time difference based on the other second initial time differences among the second initial time differences of the at least two photon signal pairs, excluding the intermediate time difference, to obtain a target time difference.

[0160] In one embodiment, when the processor executes the computer program, it also performs the following steps: inputting the time information in all photon signals into a pre-trained time reconstruction model to obtain the target time difference.

[0161] In one embodiment, when the processor executes the computer program, it also performs the following steps: inputting the time and energy information of all photon signals into the time reconstruction model to obtain the target time difference.

[0162] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0163] Acquire photon signals and determine photon signal pairs based on the photon signals;

[0164] The response line is determined based on the photon signal pairs, and the position information of the annihilation event on the response line is determined based on the target time difference between the photon signal pairs; the target time difference between the photon signal pairs is determined according to the steps performed in the above embodiments.

[0165] Image reconstruction is performed based on response lines and location information to obtain positron emission tomography (PET) images.

[0166] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, the computer program performing the following steps when executed by a processor:

[0167] For each detection module, the photon signal received by each silicon photomultiplier tube unit in the detection module is acquired; the photon signal includes time information;

[0168] Based on the time information in all photon signals, determine the target time difference between the photon signal pairs received by the corresponding detection modules.

[0169] In one embodiment, when the computer program is executed by the processor, it further performs the following steps: for each detection module, determining a first initial time difference based on the time information of the photon signal corresponding to the detection module; and determining a target time difference based on the first initial time difference of all photon signals.

[0170] In one embodiment, when the computer program is executed by the processor, it further performs the following steps: determining a second initial time difference between at least two photon signal pairs based on the time information in all photon signals; selecting an intermediate time difference from the second initial time differences between the at least two photon signal pairs; and optimizing the intermediate time difference based on the other second initial time differences among the second initial time differences of the at least two photon signal pairs, excluding the intermediate time difference, to obtain a target time difference.

[0171] In one embodiment, when the computer program is executed by the processor, it also performs the following steps: inputting the time information in all photon signals into a pre-trained time reconstruction model to obtain the target time difference.

[0172] In one embodiment, when the computer program is executed by the processor, it also performs the following steps: inputting the time and energy information of all photon signals into the time reconstruction model to obtain the target time difference.

[0173] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0174] Acquire photon signals and determine photon signal pairs based on the photon signals;

[0175] The response line is determined based on the photon signal pairs, and the position information of the annihilation event on the response line is determined based on the target time difference between the photon signal pairs; the target time difference between the photon signal pairs is determined according to the steps performed in the above embodiments.

[0176] Image reconstruction is performed based on response lines and location information to obtain positron emission tomography (PET) images.

[0177] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, performs the following steps:

[0178] For each detection module, the photon signal received by each silicon photomultiplier tube unit in the detection module is acquired; the photon signal includes time information;

[0179] Based on the time information in all photon signals, determine the target time difference between the photon signal pairs received by the corresponding detection modules.

[0180] In one embodiment, when the computer program is executed by the processor, it further performs the following steps: for each detection module, determining a first initial time difference based on the time information of the photon signal corresponding to the detection module; and determining a target time difference based on the first initial time difference of all photon signals.

[0181] In one embodiment, when the computer program is executed by the processor, it further performs the following steps: determining a second initial time difference between at least two photon signal pairs based on the time information in all photon signals; selecting an intermediate time difference from the second initial time differences between the at least two photon signal pairs; and optimizing the intermediate time difference based on the other second initial time differences among the second initial time differences of the at least two photon signal pairs, excluding the intermediate time difference, to obtain a target time difference.

[0182] In one embodiment, when the computer program is executed by the processor, it also performs the following steps: inputting the time information in all photon signals into a pre-trained time reconstruction model to obtain the target time difference.

[0183] In one embodiment, when the computer program is executed by the processor, it also performs the following steps: inputting the time and energy information of all photon signals into the time reconstruction model to obtain the target time difference.

[0184] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0185] Acquire photon signals and determine photon signal pairs based on the photon signals;

[0186] The response line is determined based on the photon signal pairs, and the position information of the annihilation event on the response line is determined based on the target time difference between the photon signal pairs; the target time difference between the photon signal pairs is determined according to the steps performed in the above embodiments.

[0187] Image reconstruction is performed based on response lines and location information to obtain positron emission tomography (PET) images.

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

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

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

Claims

1. A method for determining time difference, characterized in that, An application is made in a positron emission tomography (PET) system, the PET system comprising at least two corresponding detection modules, each detection module comprising a silicon photomultiplier tube array, the silicon photomultiplier tube array comprising at least two silicon photomultiplier tube units, the method comprising: For each of the detection modules, the photon signal received by each silicon photomultiplier tube unit in the detection module is acquired; the photon signal includes time information; Based on the time information in all the photon signals, the target time difference between the photon signal pairs received by the corresponding detection module is determined.

2. The method according to claim 1, characterized in that, Determining the target time difference of the corresponding photon signal pair received by the detection module based on the time information in all the photon signals includes: For each of the detection modules, a first initial time difference is determined based on the time information of the photon signal corresponding to the detection module; The target time difference is determined based on the first initial time difference of all the photon signals.

3. The method according to claim 1, characterized in that, Determining the target time difference of the corresponding photon signal pair received by the detection module based on the time information in all the photon signals includes: Based on the timing information in all the photon signals, determine a second initial time difference for at least two photon signal pairs; An intermediate time difference is selected from the second initial time differences of the at least two photon signal pairs, and the intermediate time difference is optimized based on other second initial time differences among the at least two photon signal pairs excluding the intermediate time difference, to obtain the target time difference.

4. The method according to claim 1, characterized in that, Determining the target time difference between corresponding pairs of photon signals received by the detection module based on the time information in all the photon signals includes: The time information from all the photon signals is input into a pre-trained time reconstruction model to obtain the target time difference.

5. The method according to claim 4, characterized in that, The photon signal includes energy information; the step of inputting the time information from all the photon signals into a pre-trained time reconstruction model to obtain the target time difference includes: The time and energy information of all the photon signals are input into the time reconstruction model to obtain the target time difference.

6. An imaging method, characterized in that, The method includes: Acquire photon signals and determine photon signal pairs based on the photon signals; A response line is determined based on the photon signal pairs, and the position information of the annihilation event on the response line is determined based on the target time difference between the photon signal pairs; the target time difference between the photon signal pairs is determined by the method according to any one of claims 1-5. Image reconstruction is performed based on the response line and the location information to obtain a positron emission tomography (PET) image.

7. A positron emission tomography (PET) system, characterized in that, It includes at least two corresponding detection modules and a signal processing module. Each detection module includes a silicon photomultiplier tube array, and the silicon photomultiplier tube array includes at least two silicon photomultiplier tube units. The signal processing module is connected to the detection module. The signal processing module is used to acquire the photon signal received by each silicon photomultiplier tube unit in the detection module, and determine the target time difference between the corresponding photon signal pairs received by the detection module based on the time information in all the received photon signals.

8. The positron emission tomography (PET) system according to claim 7, characterized in that, The detection module further includes at least one crystal. For each crystal, a dual-end readout design is adopted. The silicon photomultiplier array is arranged on the side of each crystal away from the imaging object. Any one of silicon photomultiplier array, silicon photomultiplier tube and photon detector is arranged on the side of the crystal close to the imaging object.

9. The positron emission tomography (PET) system according to claim 8, characterized in that, The crystal includes a first crystal and a second crystal, and a reflective film is disposed between the first crystal and the second crystal.

10. A time difference determination device, characterized in that, An apparatus for use in positron emission tomography (PET) imaging systems, wherein the PET imaging system includes at least two corresponding detection modules, each detection module includes a silicon photomultiplier tube array, the silicon photomultiplier tube array includes at least two silicon photomultiplier tube units, and the apparatus includes: The acquisition module is used to acquire, for each of the detection modules, the photon signal received by each silicon photomultiplier tube unit in the detection module; the photon signal includes time information; The determining module is used to determine the target time difference between the corresponding photon signal pairs received by the detection module based on the time information in all the photon signals.

11. An imaging device, characterized in that, The device includes: An acquisition module is used to acquire photon signals and determine photon signal pairs based on the photon signals; A determining module is configured to determine a response line based on the photon signal pairs, and to determine the position information of the annihilation event on the response line based on the target time difference between the photon signal pairs; the target time difference between the photon signal pairs is determined by the apparatus according to claim 10; The reconstruction module is used to reconstruct the image based on the response line and the position information to obtain a positron emission tomography (PET) image.

Images