A time correction method, apparatus, electronic device, and storage medium for a PET system

Abstract

This application relates to a time correction method, apparatus, electronic device, and storage medium for a PET system. The method includes: acquiring the position information of a line source in a phantom; calculating first distribution data of coincidence events related to the crystal based on the position information of the line source and the time position information of the crystal in the PET system; and correcting the time offset of the crystal based on the first distribution data. This application achieves crystal-level time offset correction, solving the problem of inaccurate crystal time correction in existing PET systems.

Description

Technical Field

[0001] This application relates to the field of medical imaging, and in particular to a time correction method, apparatus, electronic device, and storage medium for a PET system. Background Technology

[0002] Applying Time of Flight (TOF) information to the image reconstruction process in PET (Positron Emission Computed Tomography) systems can help improve the accuracy of image reconstruction and quantitative analysis. In practical applications, the accuracy of the TOF information measurement itself is crucial. To ensure the accuracy of the measured TOF information, the PET system needs to perform necessary time calibration, measuring the TOF offset of each crystal (or module), which is recorded as a calibration table.

[0003] Currently, there are two commonly used time correction methods for PET systems based on standard phantoms: one is the rotating linear radiation source experiment, which uses a rotating linear source to rotate around the center point of the PET system, passing near each crystal, and compares the time difference of the counts reaching the two crystals on each response line with the time deviation caused by the position of the linear source to obtain the time measurement deviation between the two crystals. The other is to use a cylindrical radiation source phantom placed at the center of the system, using a centrally symmetrical cylindrical phantom (including: uniform water phantom, annular water phantom, etc.), with its axis placed on the axis of the PET system, and statistically analyze the distribution of the time difference of all coincidence events related to a certain crystal A reaching the two crystals, and compare the center of the distribution with the default value (0) to obtain the time deviation of a certain crystal A.

[0004] The first method involves a complex rotating wire source experimental fixture, and the positioning accuracy of the fixture affects the accuracy of the results, making it very inconvenient to use in practical work. The second method suffers from two problems: firstly, due to the size of the cylindrical phantom itself, the statistical coincidence events include many scattered events in addition to the actual events, affecting the accuracy of the results; secondly, in actual operation, the phantom may deviate from the central axis of the system, and this positional deviation also affects the accuracy of the calibration results. Both methods suffer from inaccurate crystal time calibration.

[0005] There is currently no effective solution to the problem of inaccurate time correction of crystals in existing PET systems. Summary of the Invention

[0006] This embodiment provides a time correction method, apparatus, electronic device, and storage medium for a PET system to solve the problem of inaccurate time correction of crystals in existing PET systems.

[0007] Firstly, this embodiment provides a time correction method for a PET system, the method comprising:

[0008] Obtain the position information of the line source of the model;

[0009] Based on the location information of the line source and the time location information of the crystal in the PET system, calculate the first distribution data of coincidence events related to the crystal;

[0010] The time offset of the crystal is corrected based on the first distribution data.

[0011] In some embodiments, the time position information of the crystal includes the time offset of the crystal and the position information of the crystal.

[0012] In some embodiments, the first distribution data is discrete data related to the time difference Δt and the distance r; wherein the time difference Δt is the time difference between the coincidence event associated with the crystal and the crystals at both ends of the response line after removing the influence of positional deviation, and r is the distance from the line source to the response line.

[0013] In some embodiments, the method further includes:

[0014] Calculate the scattering event count of the crystal;

[0015] The scattering event counts of the crystal in the first distribution data are removed to obtain the second distribution data of coincidence events related to the crystal.

[0016] In some embodiments, correcting the time offset of the crystal based on the first distribution data includes:

[0017] Spatial dimension calculation is performed on the second distribution data to obtain third distribution data of coincidence events related to the crystal;

[0018] The time offset of the crystal is corrected based on the third distribution data.

[0019] In some embodiments, correcting the time offset of the crystal based on the third distribution data includes:

[0020] The time residual deviation of the crystal is calculated based on the third distribution data, and the time offset of the crystal is corrected based on the time residual deviation of the crystal.

[0021] In some embodiments, calculating first distribution data of coincidence events related to the crystal based on the location information of the line source and the temporal location information of the crystal in the PET system includes:

[0022] Based on the time position information of the crystal, calculate the time position information of the coincidence events related to the crystal;

[0023] Based on the location information of the line source and the temporal location information of the coincidence events related to the crystal, the first distribution data of the coincidence events related to the crystal is calculated.

[0024] Secondly, this embodiment provides a time correction device for a PET system, the device comprising:

[0025] The acquisition module is used to acquire the position information of the line source of the model;

[0026] The calculation module is used to calculate the first distribution data of coincidence events related to the crystal based on the position information of the line source and the time position information of the crystal in the PET system;

[0027] The correction module is used to correct the time offset of the crystal based on the first distribution data.

[0028] Thirdly, this embodiment provides an electronic device including a memory and a processor, wherein the memory stores a computer program and the processor is configured to run the computer program to perform the time correction method for the PET system described in the first aspect.

[0029] Fourthly, this embodiment provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the time correction method for the PET system described in the first aspect.

[0030] Compared with the prior art, the time correction method, apparatus, electronic device and storage medium of the PET system provided in this embodiment calculates the first distribution data of coincidence events related to each crystal based on the position information of the line source and the time position information of the crystals in the PET system. Based on the first distribution data, the time offset of each crystal is corrected, thereby realizing the correction of the time offset at the crystal level and solving the problem of inaccurate time correction of crystals in the prior art.

[0031] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. Attached Figure Description

[0032] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0033] Figure 1 This is a hardware structure block diagram of a terminal that executes a time correction method for a PET system according to this embodiment;

[0034] Figure 2 This is a flowchart of a time correction method for a PET system according to this embodiment;

[0035] Figure 3 This is a preferred flowchart of a time correction method for a PET system according to this embodiment;

[0036] Figure 4 This is a schematic diagram showing the positional relationship between the line source and the response line of the phantom in this embodiment;

[0037] Figure 5 This is a schematic diagram of the correction result of the time correction method for the PET system provided in this embodiment;

[0038] Figure 6 This is the system flight time histogram for this embodiment;

[0039] Figure 7 This is a structural block diagram of a time correction device for a PET system according to this embodiment. Detailed Implementation

[0040] To better understand the purpose, technical solution, and advantages of this application, the application is described and illustrated below in conjunction with the accompanying drawings and embodiments.

[0041] Unless otherwise defined, the technical or scientific terms used in this application shall have the general meaning as understood by one of ordinary skill in the art to which this application pertains. Words such as “a,” “an,” “an,” “the,” “the,” and “these,” used in this application, do not indicate quantitative limitation and may be singular or plural. The terms “comprising,” “including,” “having,” and any variations thereof used in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that comprises a series of steps or modules (units) is not limited to the listed steps or modules (units) but may include steps or modules (units) not listed, or may include other steps or modules (units) inherent to such processes, methods, products, or devices. The terms “connected,” “linked,” and “coupled,” used in this application, are not limited to physical or mechanical connections but may include electrical connections, whether direct or indirect. The term “multiple” used in this application refers to two or more. The "and / or" operator describes the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: A alone, A and B simultaneously, and B alone. Typically, the character " / " indicates that the objects before and after it are in an "or" relationship. The terms "first," "second," and "third," etc., used in this application are merely for distinguishing similar objects and do not represent a specific ordering of the objects.

[0042] The method embodiments provided in this example can be executed on a terminal, computer, or similar computing device. For example, it can run on a terminal. Figure 1 This is a hardware structure block diagram of a terminal executing a time correction method for a PET system according to this embodiment. For example... Figure 1 As shown, a terminal may include one or more ( Figure 1 Only one is shown in the diagram. A processor 102 and a memory 104 for storing data are also included. The processor 102 may be, but is not limited to, a microprocessor (MCU) or a programmable logic device (FPGA). The terminal may also include a transmission device 106 for communication functions and an input / output device 108. Those skilled in the art will understand that… Figure 1 The structure shown is for illustrative purposes only and does not limit the structure of the terminal described above. For example, the terminal may also include components that are larger than... Figure 1 The more or fewer components shown, or having the same Figure 1 The different configurations shown are illustrated.

[0043] The memory 104 can be used to store computer programs, such as application software programs and modules, like the computer program corresponding to the time correction method of the PET system in this embodiment. The processor 102 executes various functional applications and data processing by running the computer programs stored in the memory 104, thereby implementing the above-described method. The memory 104 may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory 104 may further include memory remotely located relative to the processor 102, and these remote memories can be connected to the terminal via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0044] The transmission device 106 is used to receive or send data via a network. This network includes a wireless network provided by the terminal's communication provider. In one example, the transmission device 106 includes a Network Interface Controller (NIC), which can connect to other network devices via a base station to communicate with the Internet. In another example, the transmission device 106 can be a Radio Frequency (RF) module used for wireless communication with the Internet.

[0045] This embodiment provides a time correction method for a PET system. Figure 2 This is a flowchart of a time correction method for a PET system according to this embodiment, as shown below. Figure 2 As shown, the process includes the following steps:

[0046] Step S210: Obtain the position information of the line source of the model.

[0047] Specifically, one set of time-resolution experimental data (multiple sets of data from high activity to low activity are collected during the experiment) is used for PET reconstruction to obtain a small-pixel, non-TOF PET reconstructed image. Based on the PET image, the actual position distribution of the line sources in the phantom is read, and a straight line equation is obtained by fitting, that is, the line source spatial position equation, which is the position information of the line sources.

[0048] The line source here refers to the line source within the phantom. While the line source positions within the phantom have theoretically set locations, in actual experiments, factors such as phantom placement deviations and bed deformation can cause these positions to deviate from the set values. By fitting an image to determine the actual line source positions, we can improve the accuracy of subsequent time deviation calculations.

[0049] Step S220: Calculate the first distribution data of coincidence events related to the crystal based on the location information of the line source and the time location information of the crystal in the PET system.

[0050] Specifically, the raw data acquired in the time-resolution experiment is parsed, and the Time-of-Flight (TOF) and spatial location information of coincidence events are read. Based on the position information of the line source of the phantom and the time position information of the crystals in the PET system obtained in step S210, the first distribution data C of all coincidence events associated with each crystal i in the time and spatial dimensions is statistically analyzed. i (Δt, r). The first distribution data is discrete data related to the time difference Δt and the distance r; where the time difference Δt is the time difference from the coincidence event related to the crystal to the crystals at both ends of the response line after removing the influence of positional bias, and r is the distance from the line source to the response line. The time position information of the crystal here includes the time offset of the crystal and the spatial position information of the crystal. Further, based on the time position information of the crystal, the time position information of the coincidence event related to the crystal is calculated, and based on the position information of the line source and the time position information of the coincidence event related to the crystal, the first distribution data C of the coincidence event related to the crystal is calculated. i (Δt, r).

[0051] Radioactive nuclides decay within the test subject, producing positrons. These positrons then encounter electrons within the test subject, resulting in electron-positron annihilation and generating a pair of gamma photons with opposite directions and the same energy. This pair of photons is absorbed by the corresponding detector crystals. The line connecting the two detector crystals that receive the gamma photons is called the response line, and the event in which the detectors receive this pair of gamma photons is called a coincidence event.

[0052] Step S230: Correct the time offset of the crystal based on the first distribution data.

[0053] Specifically, based on the first distribution data C of each crystal i obtained in step S220 i (Δt, r) is used to correct the time offset for each crystal i.

[0054] Through the above steps, based on the position information of the line source and the time position information of the crystals in the PET system, the first distribution data of the coincidence events related to each crystal is calculated. Based on the first distribution data, the time offset of each crystal is corrected, thereby realizing the correction of the time offset at the crystal level and solving the problem of inaccurate time correction of crystals in the PET system in the prior art.

[0055] In some of these embodiments, the scattering event count of the crystal is calculated, and the first distribution data C is... iThe scattering event counts of the crystal in (Δt, r) are removed to obtain the second distribution data C of the coincidence events associated with the crystal. i，true (Δt, r). For the second distribution data C i，true The spatial dimension of (Δt, r) is calculated to obtain the third distribution data C of coincidence events related to the crystal. i，true (Δt), based on the third distribution data C i，true (Δt) is used to correct the time offset of the crystal. The spatial dimension calculation here can be a summation of spatial dimensions, i.e., the third distribution data C. i，true (Δt)=∑ r C i，true (Δt, r).

[0056] In some of these embodiments, based on third distribution data C i，true (Δt), correcting for the time offset of the crystal, including: based on the third distribution data C i，true (Δt) Calculate the residual time deviation of the crystal, and correct the time offset of the crystal based on the residual time deviation. Specifically, for the third distribution data C of each crystal i... i，true Perform Gaussian fitting on (Δt), and denote the time residual deviation ΔO as the deviation between the peak position and 0. i Based on the time residual deviation ΔO i The new TOF offset, T, is obtained for each crystal. i (K) =T i (K-1) +λ·ΔO i This allows for the correction of the time offset of the crystal, where λ is the correction parameter, λ∈[0,1].

[0057] The present embodiment will now be described and illustrated through preferred embodiments.

[0058] Figure 3 This is a preferred flowchart of a time correction method for a PET system according to this embodiment, as follows: Figure 3 and Figure 4 As shown, the process includes the following steps:

[0059] Step S310: Read the actual position distribution of the line source 410 based on the PET reconstructed image, and obtain the spatial position equation of the line source by fitting.

[0060] PET reconstruction was performed using one set of time-resolution experimental data (multiple sets of data from high activity to low activity were collected during the experiment), resulting in a small-pixel, non-TOF PET reconstructed image. The actual positional distribution of the line source 410 of the phantom was read from the PET image, and a linear equation, i.e., the spatial position equation of the line source 410, was obtained through fitting. A schematic diagram of the positional relationship between the line source 410 and the response line 420 of the phantom is shown below. Figure 4 As shown.

[0061] The spatial position equation of line source 410 is:

[0062]

[0063] According to formula (2), the spatial vector of the line in the spatial position equation of line source 410 is:

[0064]

[0065] The spatial position equation of line source 410 obtained by fitting is a spatial straight line equation, as shown in formula (1). The spatial vector of the straight line of the spatial position equation of line source 410 is... It can be accessed through two points on line source 410. and The position is obtained, that is

[0066] Here, "line source 410" refers to the position of the line source 410 within the phantom. While the position of the line source 410 within the phantom has a theoretically set value, in actual experiments, factors such as phantom placement deviations and bed deformation can cause the position of the line source 410 to deviate from the set value. This application uses image fitting to determine the actual position of the line source 410, which improves the accuracy of subsequent time deviation calculations.

[0067] Step S320: Analyze the raw data collected in the time-resolution experiment, read the flight time and spatial location information of the coincidence events, and statistically analyze the distribution C of all coincidence events related to each crystal i in the time and spatial dimensions. i (Δt, r).

[0068] Specifically, the raw data acquired in the time-resolution experiment is analyzed, and the Time of Flight (TOF) and spatial location information of coincidence events are read. For each crystal i, the distribution C of all its associated coincidence events in the time and spatial dimensions is statistically analyzed. i (Δt, r).

[0069] The data collected in the experiment is NECR experimental data, which is the data acquired by the PET equipment during the scanning process. The NECR noise equivalent count rate experiment will repeat the scanning process from high activity to low activity multiple times to obtain multiple sets of PET scan data; in step S310, only one set of data with low activity needs to be used to reconstruct the image; in step S320, in order to have sufficient count statistics, data from all (or most) sets of NECR experimental data can be selected.

[0070] More specifically, for each pair of coincidence events, the spatial distance r between its response line 420 and line source 410, and the foot of the perpendicular are calculated. foot drop This is the point on the response line 420 with the shortest spatial distance to the line source 410. The unit vector of the response line 420 is calculated according to formula (3). in, and The spatial coordinates of crystals A and B at both ends of response line 420.

[0071]

[0072] Based on the unit vector of response line 420 Spatial position coordinates of crystal A The spatial vector of the line in the spatial position equation of the source line is: Line source 410 top point And use formula (4) to calculate the spatial distance r between response line 420 and line source 410:

[0073]

[0074] Based on the unit vector of response line 420 Spatial coordinates of crystal B The spatial vector of the line in the spatial position equation of the source line is: Line source 410 top point And use formula (5) to calculate the position of the perpendicular foot.

[0075]

[0076] The time difference between a pair of coincidence events recorded in the data and the crystals A and B at both ends of response line 420 is tAB. After deducting the influence of positional deviation, the time deviation of the coincidence events is... The positional deviation here is due to the deviation caused by the placement of the mold body, i.e., the deviation of the placement position is deducted.

[0077] The spatial dimension is divided into m fine, uniform scales within a range of ±2 cm (inclusive), and the time dimension is divided into n fine, uniform scales. The coincidence counts at a distance of 410 ± 2 cm from the line source are statistically distributed into a two-dimensional distribution C based on the spatial distance r and the time difference Δt. i In (Δt, r), the distribution C i (Δt, r) is a statistical distribution.

[0078] Step S330, the distribution C of each crystal i i By identifying and subtracting scattering counts from (Δt, r), the distribution C of the true coincident events is obtained. i，true (Δt, r).

[0079] Specifically, the scattering counts are identified and subtracted from the statistical distribution map of each crystal i to obtain the distribution of true coincidence events. For each crystal i in the spatial distribution, the counts at spatial positions -2em and +2em are taken as scattering counts; for counts within 2em, the corresponding scattering counts are obtained by linear interpolation of the counts at positions ±2em. Subtracting the scattering counts at each position yields the distribution C of true coincidence events. i，true (Δt, r). Linear interpolation is performed on the values ​​at ±2 em, which can be done in units of 2 mm. For example,

[0080] Step S340: Count and sum the spatial dimensions to obtain the statistical distribution C of each crystal i with respect to the time difference Δt. i，true (Δt).

[0081] Among them, C i，true (Δt)=∑ r C i，true (Δt, r), C i，true (Δt) is a one-dimensional distribution.

[0082] Step S350, based on the distribution C of each crystal i i，true (Δt) is fitted with a Gaussian matrix to obtain the time residual deviation ΔO for each crystal i. i .

[0083] Specifically, the deviation of the time at the peak position from 0 is denoted as the time residual deviation ΔO. i .

[0084] Step S360: The time residual deviation ΔO of each crystal i obtained in step S350 is... i The new TOF offset correction table for each crystal i is obtained by adding the new TOF offset correction table for each crystal i.

[0085] Specifically, the time residual deviation ΔO of each crystal i obtained in step S350 is... i This is added to the TOF offset (i.e., time-of-flight compensation) of the crystal used in step S320 to obtain a new TOF offset correction for each crystal i, i.e., T. i (K) =T i (K-1) +λ·ΔO i T i The TOF offset of crystal i. Let $\overhead$ be the TOF offset of crystal $i$ in the $K$-th correction period. Let λ be the TOF offset of crystal i in the (K-1)th correction period. Store the new TOF offsets of all crystals to form a new TOF offset correction table. Here, λ is the correction parameter, λ∈[0,1].

[0086] In step S370, using the new TOF offset correction table for each crystal i obtained in step S360, the time difference t between the coincidence event and crystals A and B at both ends of the response line 420 in step S320 is corrected. AB Repeat steps S320 to S370 until the time residual deviation ΔO of each crystal i in S350 is reached. i If all values ​​are less than the set threshold d, output the TOF offset correction table for each crystal i.

[0087] Specifically, using the new calibration table for each crystal i obtained in step S360, the time difference t between the coincidence event and crystals A and B at both ends of the response line 420 in step S320 is corrected. AB , The TOF offset of crystal A in the Kth correction period. The TOF offset of crystal B in the Kth correction period. For the time difference between a pair of coincidence events in the (K+1)th correction period and crystals A and B at both ends of response line 420, repeat steps S320 to S370 until the time residual deviation ΔO of each crystal i in S350 is reached. i If all values ​​are less than the set threshold d, then a basically stable TOF offset correction table for each crystal i is obtained.

[0088] This embodiment directly utilizes PET time-resolution experimental data (NEMANEC phantom data) for system time correction. Time-of-flight (TOF) offset correction is performed simultaneously with time-resolution testing, eliminating the need for separate time-of-flight correction experiments and reducing requirements on tooling and operation. This embodiment can calculate crystal-level correction, obtaining the TOF offset value for each crystal. Based on the non-TOF reconstructed image, the actual spatial position of the line source 410 is accurately calculated. The difference in physical distance between the line source 410 and the crystals at both ends of the response line 420 (LOR) is used as the theoretical value for correcting the time-of-flight difference of the time-of-flight event, avoiding the influence of radiation source position deviation on the correction results during experiments. The spatial distance between the line containing the response line 420 and the line containing the line source 410 is used to distinguish between scattering events and real events. The influence of scattering events is subtracted during analysis, improving the accuracy of the results. Analysis uses data from long-term, multi-scan data ranging from high to low activity, increasing statistical quantity while ensuring the universality of the results at both high and low activity levels. This embodiment can also perform TOF correction based on other TOF offset corrections using time-resolution data. Offset analysis is used as a method to detect the time-of-flight (TOF) state of a system. This embodiment is based on time-resolution experimental data and uses a standard NEC phantom, which has good generalizability.

[0089] A PET system collected time resolution test data according to the NEM-NU2-2018 standard, and the calculated time resolution of the system was 205 ps. This result deviates from the time resolution result of routine tests (196 ps) under the same conditions for this model of system at the same activity, indicating that this system may have an inaccurate time correction problem.

[0090] Using the time correction method for the PET system provided in this embodiment, the NECR data collected in this experiment were analyzed for TOF offset correction based on the time correction table at the time of data acquisition. After correction according to the time correction method for the PET system provided in this embodiment, and repeating the process five times, each crystal obtained a basically stable level of TOF offset, which was recorded in the TOF offset correction table. Figure 5 This is a schematic diagram of the correction result of the time correction method for the PET system provided in this embodiment. Figure 5 This is a crystal TOF offset correction table, where the horizontal axis represents the crystal's axial position number (i.e., Figure 5 The crystal index in axial direction (the vertical axis represents the crystal circumferential position number) is shown in the figure. Figure 5 In the crystal index (trans), the grayscale intensity represents the numerical value of the crystal's TOF offset at that location. For example... Figure 5 As shown, Figure 5The TOF offset of most crystals is relatively consistent, but there are two regions of crystals ( Figure 5 The two regions indicated by the middle arrow have relatively large TOF offsets, indicating that the crystal in these two regions of the system is undercorrected. Figure 6 This is the system flight time histogram for this embodiment. Figure 6 To ensure that the time difference distribution before and after correction truly matches the time difference distribution after the counting correction position, and to reflect the time resolution performance of the system, the curve after correction is narrower and higher, indicating that the time resolution of the system is better after correction. Among them, 610 is the curve before correction, and 620 is the curve after correction. Figure 6 The curve in the figure represents the TOF histogram of the system, which is the system's time-of-flight histogram. Figure 6 The horizontal axis in the graph represents time, with the unit being ps.

[0091] Substituting the newly obtained TOF offset correction table into the data and recalculating using the same time resolution analysis method, the system's time resolution was found to be 195 ps, which is a significant performance improvement compared to 205 ps. Figure 6 A comparison of the TOF information distribution curves before and after correction shows that the time distribution is more concentrated after correction, resulting in improved system resolution. This demonstrates that the time correction method for the PET system provided in this embodiment can accurately correct the TOF offset of each crystal in the system. After compensating for the crystal's TOF offset, the crystal's TOF offset is more accurate, and the resolution data obtained from statistics based on the crystal's TOF offset is more accurate.

[0092] This embodiment also provides a time correction device for a PET system, which is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. The terms "module," "unit," "subunit," etc., used below refer to combinations of software and / or hardware that perform a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0093] Figure 7 This is a structural block diagram of a time correction device for a PET system according to this embodiment, as shown below. Figure 7 As shown, the device includes:

[0094] The acquisition module 710 is used to acquire the position information of the line source of the mold;

[0095] Calculation module 720 is used to calculate the first distribution data of coincidence events related to the crystal based on the position information of the line source and the time position information of the crystal in the PET system;

[0096] The correction module 730 is used to correct the time offset of the crystal based on the first distribution data.

[0097] It should be noted that the above modules can be functional modules or program modules, and can be implemented through software or hardware. For modules implemented through hardware, the above modules can reside in the same processor; or the above modules can be located in different processors in any combination.

[0098] This embodiment also provides an electronic device including a memory and a processor, the memory storing a computer program and the processor being configured to run the computer program to perform the steps in any of the above method embodiments.

[0099] Optionally, the electronic device may further include a transmission device and an input / output device, wherein the transmission device is connected to the processor and the input / output device is connected to the processor.

[0100] Optionally, in this embodiment, the processor can be configured to perform the following steps via a computer program:

[0101] S1, obtain the position information of the line source of the model.

[0102] S2, based on the location information of the line source and the time location information of the crystal in the PET system, calculate the first distribution data of coincidence events related to the crystal.

[0103] S3, based on the first distribution data, correct the time offset of the crystal.

[0104] It should be noted that the specific examples in this embodiment can refer to the examples described in the above embodiments and optional implementations, and will not be repeated in this embodiment.

[0105] Furthermore, in conjunction with the time correction method for a PET system provided in the above embodiments, this embodiment can also provide a storage medium for implementation. The storage medium stores a computer program; when executed by a processor, the computer program implements the steps of any of the time correction methods for a PET system in the above embodiments.

[0106] It should be understood that the specific embodiments described herein are merely illustrative of the application and not intended to limit it. All other embodiments derived by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0107] Obviously, the accompanying drawings are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar situations based on these drawings without any creative effort. Furthermore, it is understood that although the work done in this development process may be complex and lengthy, for those skilled in the art, certain design, manufacturing, or production modifications made based on the technical content disclosed in this application are merely conventional technical means and should not be considered as insufficient disclosure of this application.

[0108] The term "embodiment" in this application refers to a specific feature, structure, or characteristic described in connection with an embodiment that may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily imply the same embodiment, nor does it imply that it is mutually exclusive with or independent of other embodiments. It will be clearly or implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0109] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of patent protection. 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 scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A method of time correction of a PET system, characterized by, The method includes: Obtain the position information of the line source of the model; According to the position information of the line source and the time position information of the crystal of the PET system, first distribution data of coincidence events related to the crystal are calculated; the first distribution data is discrete data related to time difference and distance r; wherein the time difference is the time difference of coincidence events related to the crystal to the crystals at both ends of the response line after removing the position bias effect, and r is the distance of the line source to the response line; The time offset of the crystal is corrected based on the first distribution data.

2. The time correction method for the PET system according to claim 1, characterized in that, The time position information of the crystal includes the time offset of the crystal and the position information of the crystal.

3. The time correction method for a PET system according to any one of claims 1 to 2, characterized in that, The method further includes: Calculate the scattering event count of the crystal; The scattering event counts of the crystal in the first distribution data are removed to obtain the second distribution data of coincidence events related to the crystal.

4. The time correction method for the PET system according to claim 3, characterized in that, The step of correcting the time offset of the crystal based on the first distribution data includes: Spatial dimension calculation is performed on the second distribution data to obtain third distribution data of coincidence events related to the crystal; The time offset of the crystal is corrected based on the third distribution data.

5. The time correction method for a PET system according to claim 4, characterized in that, The step of correcting the time offset of the crystal based on the third distribution data includes: The time residual deviation of the crystal is calculated based on the third distribution data, and the time offset of the crystal is corrected based on the time residual deviation of the crystal.

6. The time correction method for a PET system according to any one of claims 1 to 2, characterized in that, The step of calculating the first distribution data of coincidence events related to the crystal based on the position information of the line source and the time position information of the crystal in the PET system includes: Based on the time position information of the crystal, calculate the time position information of the coincidence events related to the crystal; Based on the location information of the line source and the temporal location information of the coincidence events related to the crystal, the first distribution data of the coincidence events related to the crystal is calculated.

7. A time correction device for a PET system, characterized in that, The device includes: The acquisition module is used to acquire the position information of the line source of the model; The calculation module is used to calculate first distribution data of coincidence events related to the crystal based on the position information of the line source and the time position information of the crystal in the PET system; the first distribution data is related to the time difference. Discrete data related to distance r; wherein, the time difference To remove the influence of positional deviation, the time difference between the coincidence event associated with the crystal and the crystals at both ends of the response line is given; r is the distance from the line source to the response line. The correction module is used to correct the time offset of the crystal based on the first distribution data.

8. An electronic device comprising a memory and a processor, characterized in that, The memory stores a computer program, and the processor is configured to run the computer program to perform the time correction method for the PET system according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the time correction method for the PET system according to any one of claims 1 to 6.

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