Scattering correction method, image reconstruction method, device, equipment and storage medium

Abstract

The application discloses a scatter correction method, an image reconstruction method, a device, equipment and a storage medium. The scatter correction method comprises the following steps: determining actual counts of extracorporeal scatter events on a plurality of response lines according to time-of-flight information of coincidence events on the plurality of response lines, wherein the plurality of response lines comprise response lines passing through a target object; obtaining total scatter event estimated counts and extracorporeal scatter event estimated counts on the plurality of response lines; and determining total scatter event counts on the plurality of response lines according to the actual counts of extracorporeal scatter events, the total scatter event estimated counts and the extracorporeal scatter event estimated counts. The scheme of the application can solve the problem of insufficient number of response lines (LOR) and coincidence event counts in a conventional scatter correction tail fitting algorithm.

Description

Technical Field

[0001] The present application relates to the field of nuclear detection, and specifically to a scatter correction method, an image reconstruction method, an apparatus, a device, and a storage medium. Background Art

[0002] Radiation tomography is one of the most important technologies currently used to detect the internal structure of objects, and is widely used in various fields, including medical diagnosis. By detecting gamma photons emitted from an object outside the object and reconstructing the image, internal information of the object can be observed non-invasively. Radiation tomography specifically includes positron emission tomography (PET).

[0003] In PET imaging, gamma photons generated by positron annihilation have a certain probability of undergoing Compu scattering or Rayleigh scattering in the human body, thus changing the gamma photon's flight direction. When performing gamma photon coincidence, some scattered gamma photons are inevitably counted. A pair of coincidence events in which at least one gamma photon has been scattered is called a scattering event.

[0004] Because the annihilation position information provided by scattering events is erroneous, it increases image noise and reduces image contrast during imaging. Therefore, the influence of scattering events needs to be eliminated during reconstruction. Currently, commonly used scatter correction techniques include image-based scattering event estimation methods, including single scattering estimation, multiple scattering estimation, and scattering estimation based on Monte Carlo simulation. These methods are similar in that they first perform image reconstruction without scattering correction. The resulting image is then used as a drug activity distribution map, and mathematical methods are used to estimate the proportion of scattering events on each line of response. After obtaining the proportion of scattering events on each line of response, this proportion is restored to the real projection data domain. Specifically, assuming that the lines of response (LORs) that do not pass through the human body contain no true events, the scattering counts of each line of response that does not pass through the human body are measured, i.e., the scattering counts of the LORs outside the human body. Based on this scattering count and the aforementioned proportion, the scattering count estimate for each LOR is obtained. These methods can also be referred to as tail fitting methods.

[0005] However, the current tail fitting method has the following disadvantages: it can only be fitted using the counts on the LORs outside the scanned object, and its accuracy and stability are severely limited by the number of LORs in vitro and the counts on the LORs. In the following situations, the tail fitting effect will become worse: 1. When the diameter of the scanned object is close to the diameter of the imaging field of view (FOV), such as in obese people, the number of LORs in vitro will decrease sharply; 2. For open PET systems such as flat-panel PET, the projection data is truncate, and at some angles there may even be no LORs in vitro for tail fitting; 3. For low-data imaging scenarios such as low-dose scanning and dynamic scanning, the counts on the LORs in vitro will be extremely low. The above situations will further reduce the counts of tail fitting using only LORs in vitro, resulting in reduced imaging accuracy and quality.

[0006] The description of the background technology is only for facilitating understanding of the relevant technology in this field and is not regarded as an admission of the prior art. Summary of the Invention

[0007] Therefore, the present application intends to provide a scatter correction method, an image reconstruction method, an apparatus, an electronic device, and a storage medium, which utilize coincident events located outside the human body on the response line (LOR) to fit the scatter factor, and realize scatter correction fitting of more response lines based on time of flight (TOF) information, thereby solving the problem of insufficient number of available response lines (LOR) and coincident event count in traditional scatter correction tail fitting algorithms.

[0008] In a first aspect, a scatter correction method is provided, which may include:

[0009] determining an actual count of in vitro scattered events located outside the body of the target object on a plurality of lines of response based on time-of-flight information of coincident events on the plurality of lines of response, wherein the plurality of lines of response include a line of response passing through the target object;

[0010] Obtaining an estimated total scattering event count and an estimated in vitro scattering event count on the plurality of response lines; and

[0011] The total scattered event counts on the plurality of response lines are determined based on the actual in vitro scattered event counts, the estimated total scattered event counts, and the estimated in vitro scattered event counts.

[0012] In an embodiment of the present application, determining the actual count of in vitro scattering events located outside the body of the target object on the multiple response lines based on the flight time information of the coincident events on the multiple response lines includes:

[0013] Determining a time difference error range or a spatial position error range of the event according to the flight time information;

[0014] An equivalent pixel value corresponding to the time difference error range or the spatial position error range is determined, and an actual count of the in vitro scattering events is determined in the coincident event based on the equivalent pixel value, wherein the equivalent pixel value is an equivalent pixel integral value.

[0015] In an embodiment of the present application, determining the actual count of in vitro scattering events located outside the body of the target object on the multiple response lines based on the flight time information of the coincident events on the multiple response lines includes:

[0016] Determining a time difference error range or a spatial position error range of the event according to the flight time information;

[0017] determining, according to the time difference error range or the spatial position error range, an estimated in vitro event located outside the target object in the plurality of response lines;

[0018] Determine an equivalent pixel value corresponding to a time difference error range or a spatial position error range of the estimated in vitro event, and determine an actual count of the in vitro scattering events in the estimated in vitro event based on the equivalent pixel value, wherein the equivalent pixel value is an equivalent pixel integral value.

[0019] In the embodiment of the present application, determining the time difference error range or spatial position error range of the event according to the flight time information includes:

[0020] Determining a time difference or a spatial position of the event according to the flight time information;

[0021] Determine a given distribution function error interval based on a set time difference distribution function or spatial position distribution function;

[0022] The time difference error range or the spatial position error range is determined according to the time difference or spatial position and the given distribution function error interval.

[0023] In the embodiment of the present application, determining the equivalent pixel value corresponding to the time difference error range or the spatial position error range, and determining the actual count of the in vitro scattering event in the coincident event based on the equivalent pixel value, includes:

[0024] Preset equivalent pixel threshold;

[0025] Integrating equivalent pixel values ​​within a time difference error range or a spatial position error range of the event based on the detection data or detection image of the target object to obtain the equivalent pixel integral value;

[0026] Determining a coincidence event in which the equivalent pixel integral value is less than or equal to the equivalent pixel threshold as an in vitro coincidence event;

[0027] According to the determined in vitro coincident events, actual counts of in vitro scattering events on the plurality of response lines are obtained.

[0028] In an embodiment of the present application, determining an equivalent pixel value corresponding to a time difference error range or a spatial position error range of the estimated in vitro event, and determining an actual count of the in vitro scattering events in the estimated in vitro event based on the equivalent pixel value, includes:

[0029] Preset equivalent pixel threshold;

[0030] Integrating equivalent pixel values ​​within a time difference error range or a spatial position error range of the estimated in vitro event based on the detection data or detection image of the target object to obtain the equivalent pixel integral value;

[0031] Determining an estimated in vitro event whose equivalent pixel integral value is less than or equal to the equivalent pixel threshold as an in vitro coincident event;

[0032] According to the determined in vitro coincident events, actual counts of in vitro scattering events on the plurality of response lines are obtained.

[0033] In an embodiment of the present application, determining the actual count of in vitro scattering events located outside the body of the target object on the multiple response lines based on the flight time information of the coincident events on the multiple response lines includes:

[0034] Determining a time difference or a spatial position of the event according to the flight time information;

[0035] An equivalent pixel value corresponding to the time difference or spatial position is determined, and an actual count of the in vitro scattering events is determined in the coincident event based on the equivalent pixel value, wherein the equivalent pixel value is an equivalent pixel point value.

[0036] In an embodiment of the present application, determining the equivalent pixel value corresponding to the time difference or spatial position, and determining the actual count of the in vitro scattering events in the coincident event based on the equivalent pixel value, includes:

[0037] Preset equivalent pixel threshold;

[0038] Based on the detection data or detection image of the target object, obtaining the equivalent pixel value corresponding to the time difference or spatial position of the event;

[0039] Determining a coincidence event whose equivalent pixel value is less than or equal to the equivalent pixel threshold as an in vitro coincidence event;

[0040] According to the determined in vitro coincident events, actual counts of in vitro scattering events on the plurality of response lines are obtained.

[0041] In an embodiment of the present application, determining the actual count of in vitro scattering events located outside the body of the target object on the multiple response lines based on the flight time information of the coincident events on the multiple response lines includes:

[0042] Determining a time difference or a spatial position of the event according to the flight time information;

[0043] determining, based on the time difference or spatial position, an estimated in vitro event located outside the body of the target object in the plurality of response lines;

[0044] Determine an equivalent pixel value corresponding to the time difference or spatial position of the estimated in vitro event, and determine the actual count of the in vitro scattering events in the estimated in vitro event based on the equivalent pixel value, wherein the equivalent pixel value is an equivalent pixel point value.

[0045] In an embodiment of the present application, determining the equivalent pixel value corresponding to the time difference or spatial position of the estimated external event, and based on the equivalent pixel value, includes:

[0046] Preset equivalent pixel threshold;

[0047] Based on the detection data or detection image of the target object, obtaining the equivalent pixel value corresponding to the time difference or spatial position of the estimated external event;

[0048] Determine the estimated in vitro event whose equivalent pixel value is less than or equal to the equivalent pixel threshold as an in vitro coincident event;

[0049] According to the determined in vitro coincident events, actual counts of in vitro scattering events on the plurality of response lines are obtained.

[0050] In the embodiment of the present application, the preset equivalent pixel threshold includes:

[0051] The equivalent pixel threshold is set according to the equivalent pixel integral of a response line passing through the center of the imaging field of view (FOV) of the radiation detection device in an air environment.

[0052] In the embodiment of the present application, obtaining actual counts of in vitro scattering events on the plurality of response lines according to the determined in vitro coincident events includes:

[0053] determining an actual count of in vitro coincident events across the plurality of lines of response;

[0054] determining an actual count of in vitro random events across the plurality of lines of response;

[0055] The actual counts of the in vitro scattered events on the plurality of response lines are determined based on the actual counts of the in vitro coincident events and the in vitro random events on the plurality of response lines.

[0056] In an embodiment of the present application, the equivalent pixel value includes one or more of a pixel value of a detection image or a sinogram, a standard uptake value of detection data, or an attenuation coefficient value.

[0057] In an embodiment of the present application, determining the total scattered event counts on the plurality of response lines according to the actual in vitro scattered event counts, the estimated total scattered event counts, and the estimated in vitro scattered event counts includes:

[0058] determining a scattering event count scaling factor using the actual in vitro scattering event count and the estimated in vitro scattering event count;

[0059] The estimated total scattered event count is processed using the scattered event count scaling factor to determine a total scattered event count over the plurality of lines of response.

[0060] In an embodiment of the present application, the plurality of response lines are all response lines in an imaging field of view (FOV) of the radiation detection device, wherein the plurality of response lines include response lines passing through the target object and response lines located outside the target object.

[0061] In a second aspect, an image reconstruction method is provided, which may include:

[0062] Acquiring detection data, including coincident events located on multiple response lines;

[0063] performing scatter correction on the detection data using the total scattering event counts on the plurality of response lines determined by the scatter correction method described in the embodiments of the present application; and

[0064] Image reconstruction is performed on the scatter-corrected detection data.

[0065] In a third aspect, a scatter correction device is provided, which may include:

[0066] a first determining unit configured to determine an actual count of in vitro scattered events located outside the body of the target object on a plurality of response lines based on time-of-flight information of coincident events on the plurality of response lines, wherein the plurality of response lines include a response line passing through the target object;

[0067] an acquisition unit configured to acquire an estimated total scattering event count and an estimated in vitro scattering event count on the plurality of response lines; and

[0068] The second determining unit is configured to determine the total scattered event counts on the plurality of response lines according to the actual in vitro scattered event counts, the total scattered event estimated counts and the in vitro scattered event estimated counts.

[0069] In a fourth aspect, an image reconstruction apparatus is provided, which may include:

[0070] an acquisition unit configured to acquire detection data including coincident events located on a plurality of response lines;

[0071] a scatter correction unit configured to perform scatter correction on the detection data using the total scattering event counts on the plurality of response lines determined by the scatter correction method according to the embodiment of the present application; and

[0072] The image reconstruction unit is configured to perform image reconstruction on the scatter-corrected detection data.

[0073] In a fifth aspect, an electronic device is provided, which may include: a processor and a memory storing a computer program, wherein the processor is configured to implement the method described in the embodiment of the present application when running the computer program.

[0074] In a sixth aspect, a storage medium is provided, wherein the storage medium stores a computer program, and the computer program is configured to implement the method described in the embodiments of the present application when executed.

[0075] The solution of the embodiment of the present application utilizes coincident events located outside the human body on the response line (LOR) to fit the scattering factor, and realizes scattering correction fitting of more response lines based on time of flight (TOF) information, thereby solving the problem of insufficient number of available response lines (LOR) and coincident event count in traditional scattering correction tail fitting algorithms.

[0076] The optional features and other effects of the embodiments of the present application are partially described below, and partially can be understood by reading this document. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] The embodiments of the present application are described in detail with reference to the accompanying drawings. The elements shown are not limited to the scale shown in the drawings. The same or similar reference numerals in the drawings represent the same or similar elements, wherein:

[0078] Figure 1 A schematic diagram of a scattering event is shown;

[0079] Figure 2 A schematic diagram showing a known tail fitting method;

[0080] Figure 3 A flow chart of a scatter correction method according to an embodiment of the present application is shown;

[0081] Figure 4 The structure of the full response line scatter correction fitting of the scatter correction method according to the embodiment of the present application is shown;

[0082] Figure 5AA flow chart of a scatter correction method according to an embodiment of the present application is shown;

[0083] Figure 5B A flow chart of a scatter correction method according to an embodiment of the present application is shown;

[0084] Figure 5C A flow chart of a scatter correction method according to an embodiment of the present application is shown;

[0085] Figure 5D A flow chart of a scatter correction method according to an embodiment of the present application is shown;

[0086] Figure 6A A flow chart of a scatter correction method according to an embodiment of the present application is shown;

[0087] Figure 6B A flow chart of a scatter correction method according to an embodiment of the present application is shown;

[0088] Figure 7A A flow chart of a scatter correction method according to an embodiment of the present application is shown;

[0089] Figure 7B A flow chart of a scatter correction method according to an embodiment of the present application is shown;

[0090] Figure 8A A flow chart of a scatter correction method according to an embodiment of the present application is shown;

[0091] Figure 8B A flow chart of a scatter correction method according to an embodiment of the present application is shown;

[0092] Figure 9 A flow chart of a scatter correction method according to an embodiment of the present application is shown;

[0093] Figure 10 A flowchart of an image reconstruction method according to an embodiment of the present application is shown;

[0094] Figure 11 A schematic diagram of a module of a scatter correction device according to an embodiment of the present application is shown;

[0095] Figure 12 A schematic diagram of modules of an image reconstruction device according to an embodiment of the present application is shown;

[0096] Figure 13 A schematic diagram of an electronic device according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0097] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with specific embodiments and accompanying drawings. Here, the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0098] As used herein, the term "including" and its variations represent open inclusion, i.e., "including but not limited to." Unless otherwise stated, the term "or" means "and / or." The term "based on" means "based at least in part on." The terms "an example embodiment" and "an embodiment" mean "at least one example embodiment." The term "another embodiment" means "at least one additional embodiment." The terms "first," "second," etc. may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0099] The scatter correction, image reconstruction, and imaging solutions provided herein relate to radiation tomography technology, particularly positron emission tomography (PET), computed tomography (CT), and / or magnetic resonance (MR) technology, and can be applied in a variety of fields, including but not limited to medical imaging.

[0100] In an embodiment of the present application, the target object may refer to a living organism, tissue section or prosthesis injected with a radioactive compound, such as a compound labeled with a radioactive nuclide, but is not limited thereto, and it may emit radioactive rays such as beta rays and gamma rays.

[0101] The following will describe in detail specific embodiments of the present application with reference to the accompanying drawings and in comparison with known technologies.

[0102] As mentioned above and Figure 1 As shown in Figure 1, in radiation tomography, such as PET imaging, there is a certain probability that the gamma photons produced by positron annihilation will undergo Comp scattering or Rayleigh scattering in the human body, thereby changing the flight direction of the gamma photons. When performing gamma photon coincidence, some scattered gamma photons will inevitably be counted. A pair of coincidence events in which at least one gamma photon has been scattered is called a scattering event. Figure 1 As shown in Figure 2, the annihilation position information provided by the scattering event is wrong. In other words, the response line (LOR) of the annihilation position detected by the paired detectors is wrong. Figure 1 The dotted line shows the erroneous LOR. This will increase the noise in the image and reduce the image contrast, so it is necessary to eliminate the influence of scattering events during reconstruction.

[0103] Continue to refer Figure 2 In the current commonly used scatter correction technology, image-based scattering event estimation methods are usually used, including single scattering estimation, multi-scattering estimation, and scattering estimation based on Monte Carlo simulation. Figure 2 As shown, these methods all calculate the target object 290 ( Figure 2 ) of the response line 220( Figure 2 ) to obtain a scatter count estimate for each LOR that passes through or does not pass through the target object 290. Since the lines of response 220 involved in the estimated scatter counts are only the lines of response (LORs) outside the target object, these methods can also be called "tail fitting" methods.

[0104] As an illustration, herein, the in vitro line of response (LOR) 220 ( Figure 2 )、420( Figure 4 ) or the response lines that do not pass through the target object refer to the response lines that do not intersect with the target object envelope. Accordingly, the coincidence events in these external response lines (LOR) are all external coincidence events. However, the external events described in this article, such as external coincidence events or external scattering events, only refer to the estimation or determination that the event occurs outside the target object, but the response lines 421, 422 ( Figure 4 ) may pass through the target object. For example, Figure 4 The line of response (LOR) 421 (the line connecting the detectors 401 and 402) where the in vitro coincident event 431 is shown passes through the target object 490. In the embodiment of the present application, at least some of the lines of response corresponding to the in vitro events pass through the target object.

[0105] Compared with the known method, in the embodiment of the present application, Figure 3 As shown, a scatter correction method is provided. The scatter correction method can be applied to radiation detection / imaging equipment, which as mentioned above can include but is not limited to PET equipment, CT equipment and / or MR equipment.

[0106] like Figure 3 As shown, the scatter correction method may include the following steps:

[0107] The scatter correction method may include an optional pre-processing step, such as step S300.

[0108] S0: Preprocessing the collected detection data to obtain preprocessed detection data.

[0109] The pre-processed detection data includes coincident events with time of flight (TOF) information on multiple response lines.

[0110] In the embodiment of the present application, a pre-processing step may be optionally performed before the step of obtaining scatter counts.

[0111] By way of explanation and not limitation, after scanning a target object using a detector of a radiation detection device, such as a PET system, a PET / CT system, or a PET / MR system, coincident events on response lines at various projection angles within an imaging field of view (FOV) of the detector may be acquired as acquired detection data, such as acquired PET data, CT data, or MR data. In some embodiments, all response lines at all projection angles may be combined to generate an uncorrected sinogram.

[0112] In the embodiments of the present application, the collected detection data is preprocessed using random correction, attenuation correction, and normalization correction to obtain preprocessed detection data. For example, random correction can be performed using a time delay window method. The preprocessing method can be performed using known or novel preprocessing methods, and this application does not limit this. In addition, other preprocessing methods are also conceivable and fall within the scope of this application.

[0113] As an illustration, in some embodiments of the present application, certain optional method steps may be selectively performed or not performed depending on the pre-processing conditions. For example, in some embodiments, stochastic correction pre-processing is performed in the pre-processing step. In these embodiments, the step of determining the actual count of in vitro stochastic events on the line of response described below may not be performed, and this falls within the scope of the present application.

[0114] Continue to refer Figure 3 The scatter correction method of the embodiment of the present application may include step S1.

[0115] S1: determining actual counts of in vitro scattering events located outside the body of a target object on a plurality of response lines according to time-of-flight information of coincident events on the plurality of response lines.

[0116] In the embodiment of the present application, the plurality of response lines include a response line passing through the target object.

[0117] By way of explanation and not limitation, the line between two detectors that absorb gamma photons is called the Line of Response (LOR), and the location where the annihilation reaction occurs is on the LOR.

[0118] By way of explanation and not limitation, time of flight (TOF), i.e., the time of flight of a radioactive photon, such as a gamma photon, specifically refers to the time it takes for a gamma photon to undergo an annihilation reaction and be absorbed by a detector. For example, assuming T1 and T2 are the flight times of two gamma photons generated by the annihilation reaction from the time they undergo the annihilation reaction to the time they are detected by the scintillation detector, the precise spatial location of the annihilation reaction on the response line can be obtained by measuring the time of flight. The time of flight (TOF) information is typically characterized by the time difference between the arrival of two gamma photons generated by the annihilation reaction at the two detectors. The time difference multiplied by the speed of light is the distance difference, from which the spatial location on the LOR can be determined.

[0119] By way of explanation and not limitation, a coincidence time window is typically set to determine whether two gamma photon events generated by an annihilation reaction are coincident events, thereby achieving coincidence detection. The coincidence time difference between the two gamma photons detected by the two detectors on the LOR is within the coincidence time window. Optionally, coincidence event determination can also be performed by setting a coincidence energy window. Coincidence event determination can utilize known techniques and will not be elaborated upon here.

[0120] It will be appreciated that in a broader embodiment of the present application, the actual count of in vitro scattering events may include a variety of possibilities, such as including multiple response lines passing through the target object, or including response lines passing through the target object and other response lines outside the target object.

[0121] In a preferred embodiment of the present application, the plurality of response lines are all response lines in the imaging field of view (FOV) of the radiation detection device. Figure 4 Schematically, the plurality of response lines include response lines 421 and 422 that pass through the target object, and a response line 420 located outside the target object. Accordingly, in a preferred embodiment, the actual count of in vitro scattering events in the embodiments of the present application includes both in vitro scattering events included in LORs that do not pass through the target object, such as a human body, and in vitro scattering events included in LORs that pass through the target object, such as a human body.

[0122] In different embodiments of the present application, it will be understood that step S1 and its sub-steps can be used only to determine the actual count of in vitro scattering events of the response lines 421 and 422 passing through the target object. At this time, the actual count of in vitro scattering events of the response line 420 located outside the target object can be directly determined by, for example, the coincidence event count (for example, removing random events); it can also be used to simultaneously determine the actual count of in vitro scattering events of the response lines 421 and 422 passing through the target object and the response line 420 located outside the target object, all of which fall within the scope of the present invention.

[0123] In different embodiments of the present application, determining the actual count of in vitro scattering events may be implemented in different ways.

[0124] In a first embodiment, the time difference or spatial position error range is determined based on the TOF information, and the actual count of in vitro scattered events is determined accordingly by the equivalent pixel integral value. In a second embodiment, the time difference or spatial position (point) is determined based on the TOF information, and the actual count of in vitro scattered events is determined accordingly by the equivalent pixel point value. A third embodiment is similar to the first embodiment, and the actual count of in vitro scattered events is determined by the equivalent pixel integral value, but the difference is that the third embodiment first estimates the in vitro events by the time difference or spatial position (error range), and determines the actual count of in vitro scattered events from the estimated in vitro events. A fourth embodiment is similar to the second embodiment, and the actual count of in vitro scattered events is determined by the equivalent pixel point value, but the difference is that the fourth embodiment first estimates the in vitro events by the time difference or spatial position, and determines the actual count of in vitro scattered events from the estimated in vitro events.

[0125] In various embodiments, there are various different implementations. For example, in the first embodiment, different implementations may determine a time difference or spatial position based on TOF information. For example, in the first embodiment, different implementations may determine an actual count of in vitro scattering events from PET detection data, CT detection data, and / or MR detection data. For example, in the first embodiment, different implementations may use different forms of equivalent pixel values.

[0126] In a first embodiment, if Figure 5A As shown, step S1 may include step S51.

[0127] S51: Determine the time difference error range or spatial position error range that matches the event based on the flight time information.

[0128] In a specific embodiment, Figure 5B As shown, step S51 may include:

[0129] S511: Determine the time difference or spatial position of the event according to the flight time information.

[0130] There is a coincidence time difference between the two γ photons generated by the annihilation reaction (coincidence event) when they arrive at the two detectors on the response line, which can be expressed as δT k represents the detection coincidence time difference between the two γ photons produced by the (kth) annihilation reaction (coincidence event) and detected by the detector, then δT k=T1-T2, the detection time difference represents the time of flight (TOF) information, and the detection time difference multiplied by the speed of light is the detection distance difference δD. Figure 4 As shown, for example, for the coincidence event 431 on the response line 421, since the coincidence event is not at the center of the LOR (the center of the two detectors where the source is located), the detection coincidence time difference δT of the two photons generated by the coincidence event 431 can be determined based on the TOF confidence. k .

[0131] As an alternative embodiment, it is also conceivable to determine the spatial position SP of the (kth) annihilation reaction (coincidence event) k .by Figure 4 For example, based on the TOF information, the detection time difference δT of the event 431 can be determined. k , the detection distance difference δD of the two photons corresponding to the event 431 can be determined. Based on the detection distance difference and the response line 421, the spatial position SP of the corresponding event 431 can be determined. k .

[0132] As an explanation, 5A to 5D The illustrated embodiment and Figure 6A and Figure 6B In the embodiment shown, the coincident events used to determine the in vitro scattering events include all coincident events inside and outside the target object, and the coincident time difference δT is detected. k Including the detection time difference of all coincident events inside and outside the target object (spatial position SP k The true coincidence time difference t includes the true coincidence time difference of all coincidence events inside and outside the target object. Figure 7A and Figure 7B The embodiment shown and Figure 8A and Figure 8B In the embodiment shown, the matching events are pre-screened to identify estimated extracorporeal events, and then based on the time difference or spatial position information of the estimated extracorporeal events, it is determined whether they are extracorporeal scattering events, which will be described below with reference to Figure 7A and Figure 7B as well as Figure 8A and Figure 8B Provide a description.

[0133] S512: Determine a given distribution function error interval according to the set time difference distribution function or spatial position distribution function.

[0134] S513: Determine the time difference error range or the spatial position error range according to the time difference or spatial position and the given distribution function error interval.

[0135] As an explanation, due to the difference in the performance of the detectors themselves, there is a certain error in the time when the two gamma photons arrive at their respective corresponding detectors, resulting in the detection being consistent with the time difference δT k There is also a certain error. For example, if the radiation source is located at the center of the two detectors, theoretically the two gamma photons should reach the two detectors at the same time. At this time, δT k It should be zero, but due to the fluctuation of the physical properties of the detector, there may be an error in the time when the two gamma photons arrive at the two detectors, resulting in the time difference δT k There is usually a certain error, that is, δT at this time k Not zero. That is, the detection meets the time difference δT k It is not the real coincidence time difference. In this case, t represents the real coincidence time difference and the detection coincidence time difference δT k There is an error between the detected coincidence time difference t and the actual coincidence time difference t. k The error with the true time difference t is T d express.

[0136] Specifically, the detection coincidence time difference δT can be obtained based on the detector. k Then, the time difference δT corresponding to the detection is obtained. k The corresponding error interval of the coincident event is used as the integral interval for subsequent extraction and detection of coincident events in vitro.

[0137] In the embodiment of the present application, a given distribution function error interval may be determined according to a set time difference distribution function.

[0138] In a specific embodiment, taking a PET system as an example, the actual coincidence time difference t of the PET system is Gaussian distributed, and its probability density function is:

[0139]

[0140] Among them, δT k is the detection coincidence time difference between the two γ photons of the coincidence event detected by the detector respectively; t is the true coincidence time difference of the coincidence event; f(t) is the probability that the true coincidence time difference of the coincidence event is t (specifically, the true coincidence time difference of all coincidence events inside and outside the body is t).

[0141] As an explanation, from the Gaussian function theorem, we know that the standard deviation σ in this function is Where T r is the full width at half maximum (FWHM) of the Gaussian function, that is, T r The system meets the time resolution, T rFor example, it can be measured by NEMA NU2-2018 standard. According to the inherent properties of the standard Gaussian function, the Gaussian distribution density function actually conforms to the time difference t falling within [δT k -T d ,δT k +T d ] range, T d To detect the coincidence time difference δT k The error with the true time difference t.

[0142] In a specific embodiment, the true coincidence time difference t can be determined to fall within [δT k -3σ,δT k The probability of being within the interval of [+3σ] is 99.74%. Therefore, according to the Gaussian function and combined with experience, the error interval T of this embodiment can be d Set to (0, ±3σ], so that the true time difference t is consistent, that is, the time difference error range falls within [δT k -3σ,δT k +3σ].

[0143] Accordingly, based on the error interval T d This range interval can be used based on the obtained detection coincidence time difference δT k Extract all true matching events, that is, extract at least the target object outside the body (inside the 5A to 5D and Figures 6A to 6B In the embodiment, all coincident events located on the response line (inside and outside the body of the target object) are extracted to ensure that all detected in vitro coincident events of all response lines can be screened and extracted from the coincident events of multiple, preferably all, response lines. As an explanation and not limitation, the error interval T d If the range is smaller than this range, some coincidence events will not be detected, and all coincidence events cannot be obtained, which will reduce the number of subsequent coincidence events in the detection body based on all coincidence events, affecting the subsequent calculation of the total scattering event count; if the error T d If the range is larger than this range and its maximum value is larger than 3σ, some events that belong to coincident events outside the detection body may be misjudged as coincident events inside the detection body, resulting in a decrease in coincident events outside the detection body and not conducive to the subsequent calculation of the total scattering event count.

[0144] In the specific embodiment of the present invention, the time difference error range [δT k -3σ,δT k +3σ] can be applied to but not limited to PET, CT, MR and other detection data.

[0145] In an alternative embodiment, for a spatial location SP that matches an event k, the spatial position error range can be determined.

[0146] In a specific implementation of this alternative embodiment, the spatial position error range can be achieved by determining a given distribution function error interval based on a set time difference distribution function and then transforming it.

[0147] For example, for the above time error interval T d Assuming the value of σ in (0, ±3σ], the position error interval D can be determined as follows d (0, ±3δd], that is, δd=σC, where C is the speed of light. At this time, the spatial position SP k The error range is [SP k -3δd,SP k +3δd].

[0148] In a specific implementation of this alternative embodiment, a given distribution function error interval can be determined based on the set spatial position distribution function g(sp). The determination of the spatial position distribution function g(sp) and the related distribution function error interval can refer to the relevant description of the time difference embodiment above and will not be repeated here.

[0149] refer to Figure 4 , shows a spatial position error range 432 of a coincident event (not labeled) located on response line 422 (the line connecting detectors 403 and 404). Although not shown in the figure, the time difference error range of a coincident event can also be determined based on the characteristics described above.

[0150] Continue to refer Figure 5A , step S1 may further include step S53.

[0151] S53: Determine an equivalent pixel value corresponding to the time difference error range or the spatial position error range, and determine the actual count of the in vitro scattering events in the coincident events according to the equivalent pixel value.

[0152] exist Figure 5A In the illustrated embodiment, the equivalent pixel value is an equivalent pixel integral value.

[0153] In an embodiment of the present application, the equivalent pixel value includes one or more of a pixel value of a detection image or a sinogram, a standard uptake value of detection data, or an attenuation coefficient value.

[0154] In the embodiments of the present application, the equivalent pixel value can be broadly interpreted and can include both the pixel value itself and a parameter that can represent or is represented by the pixel value. In addition, the pixel value can be a pixel value in the image domain or a pixel value in the projection domain (sinogram).

[0155] For example, in one embodiment, the pixel value may be a pixel value in a reconstructed image reconstructed from the detection data (sinogram), such as a pixel integral value. In another embodiment, the pixel value may be a pixel value / grayscale value in a sinogram, such as a pixel integral value or a grayscale integral value.

[0156] For example, in another embodiment, the equivalent pixel value may be a detected uptake value or attenuation value. As previously mentioned, the detection device may include but is not limited to a PET device, a CT device, and / or an MR device. For example, for a PET device, the equivalent pixel value may be, for example, a standard uptake value SUV determined in a standard uptake matrix of the detection data, such as a standard uptake integral value, which may characterize a PET image or sinogram pixel value. For example, for a CT or MR device, the equivalent pixel value may be, for example, an attenuation coefficient (such as Hu) value determined in an attenuation coefficient (such as Hu) matrix (or attenuation factor sinogram) of the detection data, such as an attenuation coefficient integral value, which may characterize a CT / MR image or sinogram pixel value.

[0157] In a specific embodiment, Figure 5C As shown, step S53 may include:

[0158] S531: Preset an equivalent pixel threshold.

[0159] Optionally, the step S521 may include setting the equivalent pixel threshold according to an equivalent pixel integral of a response line passing through the center of an imaging field of view (FOV) of the radiation detection device in an air environment.

[0160] In the embodiment of the present application, the preset threshold is an air threshold. In a specific example, the method for determining the threshold is, assuming that the field of view is entirely air and there is no object to be detected, taking a response line passing through the center of the FOV and calculating the integral of all pixel values ​​passed by the response line, ensuring that the air threshold is the largest, to ensure that all in vitro matching events can be extracted. Specifically, this embodiment actually integrates the image pixel values ​​corresponding to the air, and uses the integral of the image pixels on the response line as the preset threshold. The threshold can thus be used as a critical point to determine whether the matching event belongs to a matching event inside the detection body or a matching event outside the detection body. The image pixel value inside the detection body is greater than the preset air threshold. As an explanation and not a limitation, the image integral value in the air is theoretically zero, but in reality it has some tiny values.

[0161] S532: Based on the detection data or detection image of the target object, the equivalent pixel values ​​located within the time difference error range or the spatial position error range of the event are integrated to obtain the equivalent pixel integral value.

[0162] In a specific embodiment, the detection coincidence time difference δT corresponding to the detected coincidence event is determined.k The error interval [δT k -3σ,δT k +3σ] is the integration interval, and the equivalent pixel value is integrated to obtain the equivalent pixel integral value. For example, a detection coincidence time difference δT corresponding to a coincidence event k The error interval [δT k -3σ,δT k +3σ], then this interval is used as the integration interval, and the pixel values ​​of the reconstructed image or sinusoidal graph within this interval are integrated to obtain the pixel integral value. The integration method can adopt Newton's method, Riemann method, numerical method, etc. The specific integration method can adopt known techniques and will not be described in detail here.

[0163] In an alternative embodiment, the spatial position SP corresponding to the detected coincidence event is determined k The error interval is the integration interval, and the equivalent pixel value is integrated to obtain the equivalent pixel integral value. For example, a spatial position SP corresponding to the event k The error interval [SP k -3δd,SP k +3δd], then take this interval as the integration interval, integrate the pixel values ​​of the sinogram within this interval (for example, a part of a row of pixels of the sinogram corresponding to the LOR) to obtain the pixel integral value.

[0164] S533: Determine a coincidence event in which the equivalent pixel integral value is less than or equal to the equivalent pixel threshold as an in vitro coincidence event.

[0165] For the purpose of explanation and not limitation, the basis for extracting the coincidence event outside the target object 290, 490 is that the equivalent pixel integral value inside the target object 290, 490 is greater than the equivalent pixel integral value outside the target object 290, 490, that is, it must be greater than the preset air threshold. In some cases, it is impossible to predict the coincidence time difference δT of a certain detection on the response line. k or spatial position SP k The corresponding coincidence event is a coincidence event outside the target object 290 or 490 or a coincidence event inside the target object 290 or 490. Therefore, the embodiment of the present application calculates the coincidence time difference δT between the target objects 290 and 490. k The error interval or spatial position SP kThe (equivalent) pixel values ​​within the error interval are integrated to obtain the (equivalent) pixel values ​​of the event within the integration interval. Since the (equivalent) pixel values ​​inside the target objects 290 and 490 are different from the (equivalent) pixel values ​​outside the target objects 290 and 490, a preset threshold is used as the critical point for the integration of the (equivalent) pixel values ​​that are consistent with the actual event inside the target objects 290 and 490 and the events that are consistent with the events outside the target objects 290 and 490. Therefore, it is determined whether the (equivalent) pixel value of the integration interval obtained is greater than or less than the critical point threshold. If it is less than or equal to the preset threshold, it means that the image integral value is within the image integral value range without the target objects 290 and 490, and the detection coincides with the time difference δT. k The corresponding coincident event is the coincident event in the target object 290, 490. If it is greater than the threshold, it means that the (equivalent) pixel integral value is within the (equivalent) pixel integral value range of the target object 290, 490. The detection coincidence time difference δT k or spatial position SP k The corresponding coincidence event is the coincidence event in the body of the target object 290, 490. Accordingly, it can be seen that if the detection coincides with the time difference δT k or spatial position SP k The corresponding coincident event is the coincident event in the target objects 290 and 490, and the detection coincident time difference δT k or spatial position SP k The part located on the response line within the body of the target object 290, 490; if the detection meets the time difference δT k or spatial position SP k The corresponding coincidence event is the coincidence event of the target object 290, 490 outside the body, so the detection coincidence time difference δT k or spatial position SP k The portion located on the line of response and outside the body of the target object 290, 490.

[0166] Correspondingly, when the (equivalent) pixel integral value is less than or equal to the preset threshold, the detection time difference δT corresponding to the coincidence event is k The error range [δT k -3σ,δT k +3σ] or spatial position SP k The error range [SP k -3δd,SP k +3δd] is less than the (equivalent) pixel value integral of the air, the event is considered to be a coincidence event outside the target object, that is, the coincidence event is considered to be outside the target object of the response line; if it is greater than the preset threshold, the detection time difference δT corresponding to the coincidence event is k The error range [δTk -3σ,δT k +3σ] or spatial position SP k The error range [SP k -3δd,SP k +3δd] is greater than the (equivalent) pixel value integral corresponding to air, the event is considered to be a coincident event in the target object body, that is, the coincident event is considered to be in the target object body part of the response line.

[0167] The following gives the time difference δT k The error range [δT k -3σ,δT k +3σ] is an expression to judge whether it is an event in the body:

[0168]

[0169] Where, i=1,2,…n, n is the nth response line; I ik is the kth matching event on the i-th LOR; x it is the pixel value of the i-th LOR in the image with a time difference of t from the two ends of the detector; X is the preset threshold.

[0170] The expression of the error range based on spatial position will not be repeated.

[0171] The following uses PET images and CT images as examples to illustrate how to extract all coincident events outside the body to be detected on each line of response LOR based on the image pixel values ​​obtained by the detection device.

[0172] For illustration, the target object of a PET detection device can be a living organism, such as a human or animal, or a prosthesis or tissue slice. PET image pixel values ​​are uncorrected pixel values ​​obtained by reconstructing the image using detection data without scatter correction. PET involves injecting drugs into the target object. In a PET image, pixels represent the activity concentration of different drugs. The PET image pixel integral value is the integral of the drug activity in the target object, expressed as the integral of the Standard Uptake Value (SUV). While the drug activity in air is theoretically zero, it is actually negligible.

[0173] The target object of the detection device CT device can be a living organism, such as a human, an animal, etc., or a prosthesis or a sliced ​​tissue. The pixel value of the CT image is an uncorrected pixel value obtained by reconstructing the image using the detection information without scatter correction. In a CT image, a CT image pixel refers to the attenuation coefficient of the tissue of the target object to X-rays. For example, if the human body is the target object, the pixel of the CT image refers to the attenuation coefficient of the human tissue to X-rays. Compared with the living tissue of the target object, the attenuation coefficient of air to X-rays is relatively small. The integral of the CT image pixel value is the integral of the attenuation coefficient of the target object to X-rays. The greater the material density of the target object, the greater the attenuation coefficient, such as the Hu value. Compared with the target object, the density of air is low but theoretically it is not 0, and the integral value of the air image is a small value.

[0174] S534: According to the determined in vitro coincident events, actual counts of in vitro scattering events on the plurality of response lines are obtained.

[0175] In some embodiments, in step S534 , scattered coincident events in the in vitro coincident events need to be excluded.

[0176] For example Figure 5D As shown, step S524 may include:

[0177] S5341: Determine the actual count of in vitro coincidence events on the plurality of response lines.

[0178] In some embodiments, the actual count of in vitro coincident events for multiple lines of response, such as all lines of response, can be obtained by summing:

[0179]

[0180] Where i = 1, 2, ... n, n is the nth response line, P i is the actual count of in vitro coincidence events for the i-th response line.

[0181] S5342: Determine the actual count of in vitro random events on the plurality of response lines;

[0182] In some embodiments, actual counts of random events in vitro can be obtained by known methods.

[0183] Specifically, in vitro random scattering events can be detected using the delayed time window method. The original signal is detected as a single event. After a 100ns delay (based on statistical principles), if another event can be found within a time window (e.g., ±2ns), and both events have energies within the coincident energy window, then it is considered a random coincident event. This method is not further described here. For example, in a PET system, the single event detected in the normal time window is the original coincident event, while the event detected using the delayed time window is a random event.

[0184] In an alternative embodiment, the optional step S5342 may be omitted, for example, scatter correction preprocessing may be performed in the preprocessing step S0.

[0185] S5343: Determine the actual count of the in vitro scattering events on the multiple response lines according to the actual count of the in vitro coincident events and the in vitro random events on the multiple response lines.

[0186] In some embodiments, the actual counts of in vitro scattered events for multiple response lines, such as all response lines, can be obtained by subtracting in vitro random events from in vitro coincident events:

[0187] S i =P i -R i

[0188] Where i = 1, 2, ... n, n is the nth response line, S i is the actual count of in vitro scattering events of the i-th response line, P i is the actual count of in vitro coincident events for the i-th response line, R i is the actual count of in vitro random events of the i-th response line.

[0189] In a second embodiment, if Figure 6A As shown, step S1 may include:

[0190] S61: Determine the time difference or spatial position of the event according to the flight time information;

[0191] S63: Determine an equivalent pixel value corresponding to the time difference or spatial position, and determine an actual count of the in vitro scattering events in the coincident events according to the equivalent pixel value.

[0192] The equivalent pixel value is an equivalent pixel point value.

[0193] like Figure 6B As shown, step S63 may include:

[0194] S631: Preset equivalent pixel threshold.

[0195] Optionally, the step S621 may include setting the equivalent pixel threshold according to an equivalent pixel integral of a response line passing through the center of an imaging field of view (FOV) of the radiation detection device in an air environment.

[0196] S632: Based on the detection data or detection image of the target object, obtain the equivalent pixel value corresponding to the time difference or spatial position of the event.

[0197] S633: Determine a coincidence event in which the equivalent pixel value is less than or equal to the equivalent pixel threshold as an in vitro coincidence event.

[0198] S634: According to the determined in vitro coincident events, actual counts of in vitro scattering events on the plurality of response lines are obtained.

[0199] exist Figure 6A and Figure 6B In the embodiment shown, it will be assumed that the detection coincides with the time difference δT k There is no error between the actual time difference t, that is, the error interval T d is 0; or, assuming spatial position SP k There is no error, that is, the error interval D d is 0.

[0200] Therefore, in Figure 6A and Figure 6B In the embodiment shown, the determined time difference δT is directly used k or spatial position SP k (point value) to determine its corresponding (equivalent) pixel (point value), Figure 6A and Figure 6B Other features of the illustrated embodiments may be referenced in a non-inconsistent manner. 5A to 5D The features of the embodiment shown are not described here in detail. Figure 6B In the embodiment shown, it is possible to Figure 5C and Figure 5D The equivalent pixel threshold is preset and the actual count of in vitro scattering is obtained by Figure 6B and Figure 5C The difference is that Figure 6B In the embodiment shown, the equivalent pixel value is compared with the preset threshold value, and Figure 5C In the illustrated embodiment, the equivalent pixel integral value is compared with a preset threshold.

[0201] In a third embodiment, as Figure 7A As shown, step S1 may include:

[0202] S71: Determine a time difference error range or a spatial position error range of the event according to the flight time information;

[0203] S72: Determining, according to the time difference error range or the spatial position error range, an estimated external event located outside the target object in the plurality of response lines;

[0204] S73: Determine an equivalent pixel value corresponding to a time difference error range or a spatial position error range of the estimated in vitro event, and determine an actual count of the in vitro scattering events in the estimated in vitro event based on the equivalent pixel value.

[0205] The equivalent pixel value is an equivalent pixel integral value.

[0206] like Figure 7B As shown, step S73 may include:

[0207] S731: Preset equivalent pixel threshold;

[0208] S732: Integrating equivalent pixel values ​​within a time difference error range or a spatial position error range of the estimated external event based on the detection data or detection image of the target object to obtain the equivalent pixel integral value;

[0209] S733: Determine the estimated in vitro event whose equivalent pixel integral value is less than or equal to the equivalent pixel threshold as an in vitro coincident event;

[0210] S734: According to the determined in vitro coincident events, actual counts of in vitro scattering events on the plurality of response lines are obtained.

[0211] exist Figure 7A and Figure 7B In the embodiment shown, 5A to 5D Compared with the embodiment shown, the step of estimating the in vitro event is added. In other words, by detecting the time difference δT k or its error range, or spatial position SP k The system then determines whether the matching event spatially intersects the target object's envelope, or its error range, and thus estimates whether the matching event is an in-vivo event. This approach has the advantage of preemptively eliminating some in-vivo events and, in some embodiments, adding a safety margin to ensure that the estimated in-vitro event is indeed an in-vitro event.

[0212] Figure 7A and Figure 7B Other features of the illustrated embodiments may be referenced in a non-inconsistent manner. 5A to 5D The features of the illustrated embodiment are not described in detail here.

[0213] In a fourth embodiment, as Figure 8A As shown, step S1 may include:

[0214] S81: Determine the time difference or spatial position of the event according to the flight time information;

[0215] S82: Determining an estimated in vitro event located outside the target object in the plurality of response lines according to the time difference or spatial position;

[0216] S83: Determine an equivalent pixel value corresponding to the time difference or spatial position of the estimated in vitro event, and determine the actual count of the in vitro scattering events in the estimated in vitro event based on the equivalent pixel value.

[0217] The equivalent pixel value is an equivalent pixel point value.

[0218] like Figure 8B As shown, step S83 may include:

[0219] S831: Preset equivalent pixel threshold;

[0220] S832: Based on the detection data or detection image of the target object, obtaining the equivalent pixel value corresponding to the time difference or spatial position of the estimated external event;

[0221] S833: Determine the estimated in vitro event whose equivalent pixel value is less than or equal to the equivalent pixel threshold as an in vitro coincident event;

[0222] S834: According to the determined in vitro coincident events, actual counts of in vitro scattering events on the plurality of response lines are obtained.

[0223] exist Figure 8A and Figure 8B In the embodiment shown, Figure 6A and Figure 6B Compared with the embodiment shown, the step of estimating the in vitro event is added. In other words, by detecting the time difference δT k , or spatial position SP k , predicting whether the matching event spatially intersects with the target object's envelope, thereby estimating whether the matching event is (estimated to be) an in-vivo event. This has the advantage of allowing some in-vivo events to be eliminated in advance. In some embodiments, a safety margin can also be added to ensure that the estimated in-vitro event is indeed an in-vitro event.

[0224] Figure 8A and Figure 8B Other features of the illustrated embodiments may be referenced in a non-inconsistent manner. Figure 6A and Figure 6B The features of the illustrated embodiment are not described in detail here.

[0225] S2: Obtaining an estimated total scattering event count on the plurality of response lines and an estimated in vitro scattering event count.

[0226] In some embodiments, the total estimated count of scattering events on each LOR can be calculated using existing methods such as single scattering simulation, multi-scattering simulation, and Monte Carlo simulation. and estimated counts of in vitro scattered events outside the target object (such as the human body) For example, these methods can be found in Ye Ting. Doctoral Dissertation - Research on Scattering Event Simulation Correction Algorithms in PET. 2011; Watson CC, Newport D, Casey M EA Single Scatter Simulation Technique for Scatter Correction in 3D PET [J]. Springer Netherlands, 1996; and Watson CC. New, Faster, Image-Based Scatter Correction for 3D PET [C] / / 1999 IEEE Nuclear Science Symposium. Conference Record. 1999 Nuclear Science Symposium and Medical Imaging Conference (Cat. No. 99CH37019). IEEE, 2002. These documents are incorporated herein by reference.

[0227] S3: Determine the total scattered event counts on the plurality of response lines according to the actual in vitro scattered event counts, the total scattered event estimated counts, and the estimated in vitro scattered event counts.

[0228] like Figure 9 As shown, step S3 may include:

[0229] S91: Determine a scattering event count scaling factor using the actual in vitro scattering event count and the estimated in vitro scattering event count.

[0230] As an illustration, since internal scattered events within a target object (e.g., a human body) cannot be directly estimated, embodiments of the present application estimate the total scattered event count on each line of response using the actual count of scattered events outside the target object on each line of response. Specifically, the actual scattered event count on each line of response (LOR) can be estimated using the same scaling factor between the actual scattered event count and the estimated scattered event count. As an illustration, prior experience or a priori information can determine that the same scaling factor between the actual scattered event count and the estimated scattered event count is the same. This scaling factor for each line of response can be denoted as E.

[0231] In some embodiments, the scaling factor E may be determined based on a least squares method.

[0232] For example, the scattering event count scaling factor E can be obtained by using the least square method according to the following formula:

[0233]

[0234] Wherein, i=1, 2,…n, and n is the nth response line.

[0235] For example, taking three response lines as an example, the estimated count of scattered events on the first response line is 900, the actual count of in vitro scattered events is 500, and the estimated count of in vitro scattered events is 495; the estimated count of scattered events on the second response line is 850, the actual count of in vitro scattered events is 600, and the estimated count of in vitro scattered events is 500; the estimated count of scattered events on the third response line is 1000, the actual count of in vitro scattered events is 550, and the estimated count of in vitro scattered events is 510. The scaling factor is:

[0236]

[0237] Wherein, i=1, 2,…n, and n is the nth response line.

[0238] In some embodiments, the scaling factor E may be determined based on the mean.

[0239] For example, the scaling factor for the scattering event counts can be obtained directly based on the ratio of the sum of the actual in vitro scattering event counts to the (mean) sum of the estimated in vitro scattering event counts using the following formula:

[0240]

[0241] Wherein, i=1, 2,…n, and n is the nth response line.

[0242] For example, taking three response lines as an example, the estimated count of scattered events on the first response line is 900, the actual count of in vitro scattered events is 500, and the estimated count of in vitro scattered events is 495; the estimated count of scattered events on the second response line is 850, the actual count of in vitro scattered events is 600, and the estimated count of in vitro scattered events is 500; the estimated count of scattered events on the third response line is 1000, the actual count of in vitro scattered events is 550, and the estimated count of in vitro scattered events is 510. The scaling factor is:

[0243]

[0244] Wherein, i=1, 2,…n, and n is the nth response line.

[0245] S92: Processing the total scattered event estimate count using the scattered event count scaling factor to determine the total scattered event counts on the plurality of response lines.

[0246] Specifically, the estimated scattering event count obtained in step S2 can be multiplied by the scaling factor E determined in step S91 to determine the actual scattering event count (total scattering event count) of each LOR:

[0247]

[0248] Wherein, i=1, 2,…n, and n is the nth response line.

[0249] With a scaling factor of 1.43, then:

[0250] The actual count of scattered events on the first response line is estimated to be:

[0251] 900X1.43=1287;

[0252] The actual count of scattered events on the second response line is estimated to be:

[0253] 850X1.43=1216;

[0254] The actual count of scattered events on the first response line is estimated to be:

[0255] 1000X1.43=1430;

[0256] With a scaling factor of 1.10, then:

[0257] The actual count of scattered events on the first response line is estimated to be:

[0258] 900X1.10=990;

[0259] The actual count of scattered events on the second response line is estimated to be:

[0260] 850X1.10=935;

[0261] The actual count of scattered events on the first response line is estimated to be:

[0262] 1000X1.10=1100.

[0263] like Figure 10 As shown, an image reconstruction method is also provided, which may include:

[0264] S101: Acquire detection data, including coincident events located on multiple response lines;

[0265] S102: performing scatter correction on the detection data using the total scattering event counts on the plurality of response lines determined by the scatter correction method; and

[0266] S103: Perform image reconstruction on the scatter-corrected detection data.

[0267] In the embodiments of the present application, the detection data may include the number of response lines and their distribution positions in the sinusoidal diagram, and may also include the time when the radioactive ray was detected, the energy of the radioactive ray, and the location of the scintillation crystal that detected the radioactive ray. Accordingly, the detection data may be subjected to scatter correction by referring to the scatter correction method described in the embodiments of the present application, which will not be further described here.

[0268] The image reconstruction may be performed using a known or novel image reconstruction method, which will not be described in detail here.

[0269] like Figure 11 As shown, a scatter correction device 1100 is also provided, which may include:

[0270] A first determining unit 1110 is configured to determine an actual count of in vitro scattered events located outside the body of the target object on a plurality of response lines based on time-of-flight information of coincident events on the plurality of response lines, wherein the plurality of response lines include a response line passing through the target object;

[0271] An acquiring unit 1120 is configured to acquire an estimated total scattering event count and an estimated in vitro scattering event count on the plurality of response lines; and

[0272] The second determining unit 1130 is configured to determine the total scattered event count on the plurality of response lines according to the actual in vitro scattered event count, the total scattered event estimated count and the in vitro scattered event estimated count.

[0273] like Figure 12 As shown, an image reconstruction device 1200 is also provided, which may include:

[0274] An acquisition unit 1210 is configured to acquire detection data, including coincident events located on a plurality of response lines;

[0275] a scatter correction unit 1220 configured to perform scatter correction on the detection data using the total scatter event counts on the plurality of response lines determined by the scatter correction method; and

[0276] The image reconstruction unit 1230 is configured to perform image reconstruction on the scatter-corrected detection data.

[0277] Those skilled in the art will understand that the devices and apparatuses described in the embodiments of the present application can be combined with the method features described in the embodiments of the present application, and vice versa.

[0278] In some embodiments, an electronic device is provided, which may include a processor and a memory storing a computer program, wherein the processor is configured to execute the method of any embodiment of the present application when running the computer program.

[0279] Figure 13 A schematic diagram of an exemplary electronic device 1300 that can implement the methods of the embodiments of the present application is shown. In some embodiments, the method may include more or fewer electronic devices than shown. In some embodiments, the method may be implemented using a single or multiple electronic devices. In some embodiments, the method may be implemented using cloud-based or distributed electronic devices.

[0280] like Figure 13 As shown, the electronic device 1300 includes a processor 1301, which can perform various appropriate operations and processes according to the programs and / or data stored in the read-only memory (ROM) 1302 or the programs and / or data loaded from the storage part 1308 into the random access memory (RAM) 1303. The processor 1301 can be a single-core or multi-core processor, or it can include multiple processors. In some embodiments, the processor 1301 can include a general-purpose main processor (such as a CPU) and one or more special coprocessors, such as a graphics processing unit (GPU), a neural network processor (NPU), a digital signal processor (DSP), or other general or application-specific integrated circuits. In the RAM 1303, various programs and data required for the operation of the electronic device 1300 are also stored. The processor 1301, ROM 1302, and RAM 1303 are connected to each other via a bus 1304. An input / output (I / O) interface 1305 is also connected to the bus 1304.

[0281] The processor and the memory are used together to execute the program stored in the memory. When the program is executed by the computer, the steps or functions of the methods described in the above embodiments can be implemented.

[0282] The following components are connected to the I / O interface 1305: an input section 1306 including a keyboard, mouse, and the like; an output section 1307 including a display and speakers; a storage section 1308 including a hard disk and the like; and a communication section 1309 including a network interface card such as a LAN card or a modem. The communication section 1309 performs communication processing via a network such as the Internet. A drive 1310 is also connected to the I / O interface 1305 as needed. Removable media 1311, such as a magnetic disk, optical disk, magneto-optical disk, semiconductor memory, and the like, is installed in the drive 1310 as needed, so that computer programs read from the media can be installed in the storage section 1308 as needed.

[0283] Figure 13 The electronic device is only schematically shown, but the electronic device according to the embodiment of the present application may include Figure 13 The electronic devices shown may have more or fewer components or may have Figure 13 The devices of the illustrated embodiments may have the same, partially the same or different architectures.

[0284] In some embodiments, the electronic device may be combined with various components to obtain methods, devices, and systems having the advantages of the present invention.

[0285] Although not shown, in some embodiments, a computer-readable storage medium is further provided, storing a computer program configured to execute any of the methods of the embodiments of the present application when executed. The computer program includes various program modules / units that constitute the apparatus according to the embodiments of the present application. When the computer program composed of the various program modules / units is executed, it can implement the functions corresponding to the various steps in the methods described in the above embodiments. The computer program can also be executed on the electronic device described in the embodiments of the present application.

[0286] The storage media in the embodiments of the present application include non-volatile and / or volatile items that can be used to store information by any method or technology. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0287] Those skilled in the art will appreciate that the embodiments of this specification may be implemented in various forms, such as methods, systems, or computer program products. Therefore, those skilled in the art will appreciate that the functional modules / units or controllers and related method steps described in the above embodiments may be implemented using software, hardware, or a combination of software / hardware.

[0288] Unless explicitly stated, the actions or steps of the methods, procedures, and embodiments of the present application do not have to be performed in a specific order and can still achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0289] In this document, multiple embodiments are described, but for the sake of brevity, the description of each embodiment is not exhaustive, and the same or similar features or parts between the embodiments may be omitted. In this document, "one embodiment", "some embodiments", "example", "specific example", or "some examples" are intended to apply to at least one embodiment or example according to the present application, rather than all embodiments. The above terms do not necessarily mean to refer to the same embodiment or example. Those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0290] While the exemplary systems and methods of the present application have been specifically shown and described with reference to the foregoing embodiments, these are merely examples of the best modes for implementing the present systems and methods. Those skilled in the art will appreciate that various changes may be made to the embodiments of the systems and methods described herein when implementing the present systems and / or methods without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. A scatter correction method, characterized in that: include: determining an actual count of in vitro scattered events located outside the body of the target object on a plurality of lines of response based on time-of-flight information of coincident events on the plurality of lines of response, wherein the plurality of lines of response include a line of response passing through the target object; Obtaining an estimated total scattering event count and an estimated in vitro scattering event count on the plurality of response lines; as well as determining a total scattered event count on the plurality of response lines based on the actual in vitro scattered event count, the estimated total scattered event count, and the estimated in vitro scattered event count; The step of determining the actual count of in vitro scattering events located outside the body of the target object on the plurality of response lines based on the flight time information of the coincident events on the plurality of response lines comprises: Determining a time difference error range or a spatial position error range of the event according to the flight time information; An equivalent pixel value corresponding to the time difference error range or the spatial position error range is determined, and an actual count of the in vitro scattering events is determined in the coincident event based on the equivalent pixel value, wherein the equivalent pixel value is an equivalent pixel integral value.

2. The scatter correction method according to claim 1, wherein: The determining, based on the flight time information, a time difference error range or a spatial position error range of the event, includes: Determining a time difference or a spatial position of the event according to the flight time information; Determine a given distribution function error interval based on a set time difference distribution function or spatial position distribution function; The time difference error range or the spatial position error range is determined according to the time difference or spatial position and the given distribution function error interval.

3. The scatter correction method according to claim 1, wherein: Determining the equivalent pixel value corresponding to the time difference error range or the spatial position error range, and determining the actual count of the in vitro scattering events in the coincident event based on the equivalent pixel value, includes: Preset equivalent pixel threshold; Integrating equivalent pixel values ​​within a time difference error range or a spatial position error range of the event based on the detection data of the target object to obtain the equivalent pixel integral value; Determining a coincidence event in which the equivalent pixel integral value is less than or equal to the equivalent pixel threshold as an in vitro coincidence event; According to the determined in vitro coincident events, actual counts of in vitro scattering events on the plurality of response lines are obtained.

4. The scatter correction method according to claim 3, wherein: The preset equivalent pixel threshold includes: The equivalent pixel threshold is set according to the equivalent pixel integral of a response line passing through the center of the imaging field of view of the radiation detection device in an air environment.

5. The scatter correction method according to claim 3, wherein: The step of obtaining actual counts of in vitro scattering events on the plurality of response lines according to the determined in vitro coincident events comprises: determining an actual count of in vitro coincident events across the plurality of lines of response; determining an actual count of in vitro random events across the plurality of lines of response; The actual counts of the in vitro scattered events on the plurality of response lines are determined based on the actual counts of the in vitro coincident events and the in vitro random events on the plurality of response lines.

6. The scatter correction method according to claim 1, wherein: The equivalent pixel value includes one or more of a pixel value of a detection image or a sinogram, and an attenuation coefficient value of detection data.

7. The scatter correction method according to claim 1, wherein: Determining the total scattered event counts on the plurality of response lines according to the actual in vitro scattered event counts, the total scattered event estimated counts, and the in vitro scattered event estimated counts includes: determining a scattering event count scaling factor using the actual in vitro scattering event count and the estimated in vitro scattering event count; The estimated total scattered event count is processed using the scattered event count scaling factor to determine a total scattered event count over the plurality of lines of response.

8. The scatter correction method according to claim 1, wherein: The plurality of response lines are all response lines in the imaging field of view of the radiation detection device, wherein the plurality of response lines include response lines passing through the target object and response lines located outside the target object.

9. A scatter correction method, characterized in that: include: determining an actual count of in vitro scattered events located outside the body of the target object on a plurality of lines of response based on time-of-flight information of coincident events on the plurality of lines of response, wherein the plurality of lines of response include a line of response passing through the target object; Obtaining an estimated total scattering event count and an estimated in vitro scattering event count on the plurality of response lines; as well as determining a total scattered event count on the plurality of response lines based on the actual in vitro scattered event count, the estimated total scattered event count, and the estimated in vitro scattered event count; The step of determining the actual count of in vitro scattering events located outside the body of the target object on the plurality of response lines based on the flight time information of the coincident events on the plurality of response lines comprises: Determining a time difference error range or a spatial position error range of the event according to the flight time information; determining, according to the time difference error range or the spatial position error range, an estimated in vitro event located outside the target object in the plurality of response lines; Determine an equivalent pixel value corresponding to a time difference error range or a spatial position error range of the estimated in vitro event, and determine an actual count of the in vitro scattering events in the estimated in vitro event based on the equivalent pixel value, wherein the equivalent pixel value is an equivalent pixel integral value.

10. The scatter correction method according to claim 9, wherein: The determining, based on the flight time information, a time difference error range or a spatial position error range of the event, includes: Determining a time difference or a spatial position of the event according to the flight time information; Determine a given distribution function error interval based on a set time difference distribution function or spatial position distribution function; The time difference error range or the spatial position error range is determined according to the time difference or spatial position and the given distribution function error interval.

11. The scatter correction method according to claim 9, wherein: Determining the equivalent pixel value corresponding to the time difference error range or the spatial position error range of the estimated in vitro event, and determining the actual count of the in vitro scattering events in the estimated in vitro event based on the equivalent pixel value, includes: Preset equivalent pixel threshold; Integrating equivalent pixel values ​​within a time difference error range or a spatial position error range of the estimated in vitro event based on the detection data of the target object to obtain the equivalent pixel integral value; Determining an estimated in vitro event whose equivalent pixel integral value is less than or equal to the equivalent pixel threshold as an in vitro coincident event; According to the determined in vitro coincident events, actual counts of in vitro scattering events on the plurality of response lines are obtained.

12. The scatter correction method according to claim 11, wherein: The preset equivalent pixel threshold includes: The equivalent pixel threshold is set according to the equivalent pixel integral of a response line passing through the center of the imaging field of view of the radiation detection device in an air environment.

13. The scatter correction method according to claim 11, wherein: The step of obtaining actual counts of in vitro scattering events on the plurality of response lines according to the determined in vitro coincident events comprises: determining an actual count of in vitro coincident events across the plurality of lines of response; determining an actual count of in vitro random events across the plurality of lines of response; The actual counts of the in vitro scattered events on the plurality of response lines are determined based on the actual counts of the in vitro coincident events and the in vitro random events on the plurality of response lines.

14. The scatter correction method according to claim 9, wherein: The equivalent pixel value includes one or more of a pixel value of a detection image or a sinogram, and an attenuation coefficient value of detection data.

15. The scatter correction method according to claim 9, wherein: Determining the total scattered event counts on the plurality of response lines according to the actual in vitro scattered event counts, the total scattered event estimated counts, and the in vitro scattered event estimated counts includes: determining a scattering event count scaling factor using the actual in vitro scattering event count and the estimated in vitro scattering event count; The estimated total scattered event count is processed using the scattered event count scaling factor to determine a total scattered event count over the plurality of lines of response.

16. The scatter correction method according to claim 9, wherein: The plurality of response lines are all response lines in the imaging field of view of the radiation detection device, wherein the plurality of response lines include response lines passing through the target object and response lines located outside the target object.

17. A scatter correction method, characterized in that: include: determining an actual count of in vitro scattered events located outside the body of the target object on a plurality of lines of response based on time-of-flight information of coincident events on the plurality of lines of response, wherein the plurality of lines of response include a line of response passing through the target object; Obtaining an estimated total scattering event count and an estimated in vitro scattering event count on the plurality of response lines; as well as determining a total scattered event count on the plurality of response lines based on the actual in vitro scattered event count, the estimated total scattered event count, and the estimated in vitro scattered event count; The step of determining the actual count of in vitro scattering events located outside the body of the target object on the plurality of response lines based on the flight time information of the coincident events on the plurality of response lines comprises: Determining a time difference or a spatial position of the event according to the flight time information; An equivalent pixel value corresponding to the time difference or spatial position is determined, and an actual count of the in vitro scattering events is determined in the coincident event based on the equivalent pixel value, wherein the equivalent pixel value is an equivalent pixel point value.

18. The scatter correction method according to claim 17, wherein: Determining the equivalent pixel value corresponding to the time difference or spatial position, and determining the actual count of the in vitro scattering events in the coincident event based on the equivalent pixel value, includes: Preset equivalent pixel threshold; Based on the detection data of the target object, the equivalent pixel value corresponding to the time difference or spatial position of the event is obtained; Determining a coincidence event whose equivalent pixel value is less than or equal to the equivalent pixel threshold as an in vitro coincidence event; According to the determined in vitro coincident events, actual counts of in vitro scattering events on the plurality of response lines are obtained.

19. The scatter correction method according to claim 18, wherein: The preset equivalent pixel threshold includes: The equivalent pixel threshold is set according to the equivalent pixel integral of a response line passing through the center of the imaging field of view of the radiation detection device in an air environment.

20. The scatter correction method according to claim 18, wherein: The step of obtaining actual counts of in vitro scattering events on the plurality of response lines according to the determined in vitro coincident events comprises: determining an actual count of in vitro coincident events across the plurality of lines of response; determining an actual count of in vitro random events across the plurality of lines of response; The actual counts of the in vitro scattered events on the plurality of response lines are determined based on the actual counts of the in vitro coincident events and the in vitro random events on the plurality of response lines.

21. The scatter correction method according to claim 17, wherein: The equivalent pixel value includes one or more of a pixel value of a detection image or a sinogram, and an attenuation coefficient value of detection data.

22. The scatter correction method according to claim 17, wherein: Determining the total scattered event counts on the plurality of response lines according to the actual in vitro scattered event counts, the total scattered event estimated counts, and the in vitro scattered event estimated counts includes: determining a scattering event count scaling factor using the actual in vitro scattering event count and the estimated in vitro scattering event count; The estimated total scattered event count is processed using the scattered event count scaling factor to determine a total scattered event count over the plurality of lines of response.

23. The scatter correction method according to claim 17, wherein: The plurality of response lines are all response lines in the imaging field of view of the radiation detection device, wherein the plurality of response lines include response lines passing through the target object and response lines located outside the target object.

24. A scatter correction method, characterized in that: include: determining an actual count of in vitro scattered events located outside the body of the target object on a plurality of lines of response based on time-of-flight information of coincident events on the plurality of lines of response, wherein the plurality of lines of response include a line of response passing through the target object; Obtaining an estimated total scattering event count and an estimated in vitro scattering event count on the plurality of response lines; as well as determining a total scattered event count on the plurality of response lines based on the actual in vitro scattered event count, the estimated total scattered event count, and the estimated in vitro scattered event count; The step of determining the actual count of in vitro scattering events located outside the body of the target object on the plurality of response lines based on the flight time information of the coincident events on the plurality of response lines comprises: Determining a time difference or a spatial position of the event according to the flight time information; determining, based on the time difference or spatial position, an estimated in vitro event located outside the body of the target object in the plurality of response lines; Determine an equivalent pixel value corresponding to the time difference or spatial position of the estimated in vitro event, and determine the actual count of the in vitro scattering events in the estimated in vitro event based on the equivalent pixel value, wherein the equivalent pixel value is an equivalent pixel point value.

25. The scatter correction method according to claim 24, wherein: The determining of the equivalent pixel value corresponding to the time difference or spatial position of the estimated external event, and based on the equivalent pixel value, includes: Preset equivalent pixel threshold; Based on the detection data of the target object, obtaining the equivalent pixel value corresponding to the time difference or spatial position of the estimated external event; Determine the estimated in vitro event whose equivalent pixel value is less than or equal to the equivalent pixel threshold as an in vitro coincident event; According to the determined in vitro coincident events, actual counts of in vitro scattering events on the plurality of response lines are obtained.

26. The scatter correction method according to claim 25, wherein: The preset equivalent pixel threshold includes: The equivalent pixel threshold is set according to the equivalent pixel integral of a response line passing through the center of the imaging field of view of the radiation detection device in an air environment.

27. The scatter correction method according to claim 25, wherein: The step of obtaining actual counts of in vitro scattering events on the plurality of response lines according to the determined in vitro coincident events comprises: determining an actual count of in vitro coincident events across the plurality of lines of response; determining an actual count of in vitro random events across the plurality of lines of response; The actual counts of the in vitro scattered events on the plurality of response lines are determined based on the actual counts of the in vitro coincident events and the in vitro random events on the plurality of response lines.

28. The scatter correction method according to claim 24, wherein: The equivalent pixel value includes one or more of a pixel value of a detection image or a sinogram, and an attenuation coefficient value of detection data.

29. The scatter correction method according to claim 24, wherein: Determining the total scattered event counts on the plurality of response lines according to the actual in vitro scattered event counts, the total scattered event estimated counts, and the in vitro scattered event estimated counts includes: determining a scattering event count scaling factor using the actual in vitro scattering event count and the estimated in vitro scattering event count; The estimated total scattered event count is processed using the scattered event count scaling factor to determine a total scattered event count over the plurality of lines of response.

30. The scatter correction method according to claim 24, wherein: The plurality of response lines are all response lines in the imaging field of view of the radiation detection device, wherein the plurality of response lines include response lines passing through the target object and response lines located outside the target object.

31. An image reconstruction method, characterized in that: include: Acquiring detection data, including coincident events located on multiple response lines; performing scatter correction on the detection data using the total scattering event counts on a plurality of response lines determined by the scatter correction method according to any one of claims 1 to 30; and Image reconstruction is performed on the scatter-corrected detection data.

32. A scattering correction device, characterized in that: include: a first determining unit configured to determine an actual count of in vitro scattered events located outside the body of the target object on a plurality of response lines based on time-of-flight information of coincident events on the plurality of response lines, wherein the plurality of response lines include a response line passing through the target object; an acquisition unit configured to acquire an estimated count of total scattered events and an estimated count of in vitro scattered events on the plurality of response lines; as well as a second determining unit configured to determine a total scattered event count on the plurality of response lines based on the actual in vitro scattered event count, the total scattered event estimated count, and the in vitro scattered event estimated count; Wherein, the first determination unit is configured to determine the time difference error range or the spatial position error range of the coincident event based on the flight time information; determine the equivalent pixel value corresponding to the time difference error range or the spatial position error range, and determine the actual count of the in vitro scattering events in the coincident event based on the equivalent pixel value, wherein the equivalent pixel value is an equivalent pixel integral value.

33. A scatter correction device, characterized in that: include: a first determining unit configured to determine an actual count of in vitro scattered events located outside the body of the target object on a plurality of response lines based on time-of-flight information of coincident events on the plurality of response lines, wherein the plurality of response lines include a response line passing through the target object; an acquisition unit configured to acquire an estimated count of total scattered events and an estimated count of in vitro scattered events on the plurality of response lines; as well as a second determining unit configured to determine a total scattered event count on the plurality of response lines based on the actual in vitro scattered event count, the total scattered event estimated count, and the in vitro scattered event estimated count; Wherein, the first determination unit is configured to determine the time difference error range or spatial position error range of the event according to the flight time information; determine the estimated in vitro event located outside the target object in the multiple response lines according to the time difference error range or spatial position error range; determine the equivalent pixel value corresponding to the time difference error range or spatial position error range of the estimated in vitro event, and determine the actual count of the in vitro scattering event in the estimated in vitro event according to the equivalent pixel value, wherein the equivalent pixel value is an equivalent pixel integral value.

34. A scatter correction device, characterized in that: include: a first determining unit configured to determine an actual count of in vitro scattered events located outside the body of the target object on a plurality of response lines based on time-of-flight information of coincident events on the plurality of response lines, wherein the plurality of response lines include a response line passing through the target object; an acquisition unit configured to acquire an estimated count of total scattered events and an estimated count of in vitro scattered events on the plurality of response lines; as well as a second determining unit configured to determine a total scattered event count on the plurality of response lines based on the actual in vitro scattered event count, the total scattered event estimated count, and the in vitro scattered event estimated count; Wherein, the first determination unit is configured to determine the time difference or spatial position of the coincident event based on the flight time information; determine the equivalent pixel value corresponding to the time difference or spatial position, and determine the actual count of the in vitro scattering events in the coincident event based on the equivalent pixel value, wherein the equivalent pixel value is an equivalent pixel point value.

35. A scattering correction device, characterized in that: include: a first determining unit configured to determine an actual count of in vitro scattered events located outside the body of the target object on a plurality of response lines based on time-of-flight information of coincident events on the plurality of response lines, wherein the plurality of response lines include a response line passing through the target object; an acquisition unit configured to acquire an estimated count of total scattered events and an estimated count of in vitro scattered events on the plurality of response lines; as well as a second determining unit configured to determine a total scattered event count on the plurality of response lines based on the actual in vitro scattered event count, the total scattered event estimated count, and the in vitro scattered event estimated count; Wherein, the first determination unit is configured to determine the time difference or spatial position of the consistent event based on the flight time information; determine the estimated in vitro event located outside the target object in the multiple response lines based on the time difference or spatial position; determine the equivalent pixel value corresponding to the time difference or spatial position of the estimated in vitro event, and determine the actual count of the in vitro scattering event in the estimated in vitro event based on the equivalent pixel value, wherein the equivalent pixel value is an equivalent pixel point value.

36. An image reconstruction device, characterized in that include: an acquisition unit configured to acquire detection data including coincident events located on a plurality of response lines; a scatter correction unit configured to perform scatter correction on the detection data using total scattering event counts on a plurality of response lines determined by the scatter correction method according to any one of claims 1 to 30; and The image reconstruction unit is configured to perform image reconstruction on the scatter-corrected detection data.

37. An electronic device, characterized in that: include: A processor and a memory storing a computer program, wherein the processor is configured to implement the method according to any one of claims 1 to 31 when running the computer program.

38. A storage medium, characterized in that The storage medium stores a computer program, which is configured to implement the method according to any one of claims 1 to 31 when executed.

Images