PET system normalization correction coefficient detection mold, method and equipment

Abstract

The present invention is applicable to the field of medical technology, and provides a detection mold, method and device for the normalization correction coefficient of a PET system. The detection mold includes: an outer tube and an inner tube of the same length, the inner diameter of the inner tube is larger than the lateral dimension of the field of view of the PET system; two end plates connected to the two end faces of the outer tube and the inner tube respectively, and a circular cylindrical space is formed between the inner wall of the outer tube, the outer wall of the inner tube and the two end plates for loading radioactive substances; at least two openings and a sealing assembly matching the openings; the openings are located on the outer tube or in the area corresponding to the space on the end plate, and at least two openings are used to inject radioactive substances. By setting the circular cylindrical space, uniform scanning of the PET system is achieved, and the detection mold itself reduces the attenuation and scattering of gamma photons, thereby improving the accuracy of the normalization correction of the PET system.

Description

Technical Field

[0001] The present application relates to the field of medical technology, and in particular to a detection mold, method and device for a normalized correction coefficient of a positron emission tomography (PET) system. Background Art

[0002] PET technology is a relatively advanced imaging technology in the field of nuclear medicine. It can detect the metabolic characteristics of the organs of organisms and has the characteristics of high sensitivity, good accuracy and accurate positioning. In PET imaging, radioactive substances that can emit positrons are injected into the body, and the positrons and electrons in the body are annihilated to produce gamma photons. The detectors surrounding the organism under test in the PET system can detect gamma photons and collect data. After that, image processing algorithms are used to form images based on the collected data.

[0003] The normalization correction of the PET system is an important process in PET image reconstruction. The normalization correction coefficient of the PET system characterizes the response of each detector unit in the PET system. Due to the individual differences of the detector units in the PET system and the differences in the positions of different detector units, the sensitivity of different detector units in the PET system varies. Therefore, it is necessary to obtain the normalization correction coefficient of the PET system in order to make corrections based on the sensitivity differences of the detector units during the imaging process.

[0004] At present, a flat-plate mold is used to detect the normalization correction coefficient of the PET system. Radioactive materials are loaded through the flat-plate mold and multi-angle rotation scanning is performed. The detection method is complicated and the scanning angle is prone to misalignment. The accuracy of the normalization correction of the PET system is very low. Summary of the invention

[0005] The invention provides a detection mold, method and equipment for a normalized correction coefficient of a PET system, which improves the accuracy of the normalized correction of the PET system.

[0006] In a first aspect, the present invention provides a detection mold for a normalized correction coefficient of a PET system, comprising:

[0007] An outer tube and an inner tube of the same length, the inner diameter of the outer tube being larger than the outer diameter of the inner tube, and the inner diameter of the inner tube being larger than the transverse dimension corresponding to the FOV of the PET system; two end plates; the two end plates are respectively connected to the two end faces of the outer tube and the inner tube, and a cylindrical space is formed between the inner wall of the outer tube, the outer wall of the inner tube and the two end plates, and the space is used to load radioactive materials; at least two openings and sealing components respectively matched with the at least two openings; the openings are located on the outer tube or in the area on the end plates corresponding to the space, and the at least two openings are used to inject the radioactive materials.

[0008] Optionally, the lengths of the outer tube and the inner tube are greater than the length of the axial field of view of the PET system.

[0009] Optionally, the wall thicknesses of the outer tube, the inner tube and the end plate are all less than or equal to 5 mm.

[0010] Optionally, the lateral thickness of the space is less than or equal to 5 mm.

[0011] Optionally, the at least two openings are located in areas on the two end plates corresponding to the space.

[0012] Optionally, the end plate is annular or circular.

[0013] Optionally, the opening is a threaded hole, and the sealing assembly includes a threaded fastener and a sealing ring.

[0014] Optionally, one of the two end plates, the outer tube and the inner tube are integrally formed.

[0015] Optionally, the outer tube and the inner tube have the same wall thickness.

[0016] Optionally, the wall thicknesses of the outer tube, the inner tube and the end plate are all the same.

[0017] In a second aspect, the present invention provides a method for detecting a normalized correction coefficient of a PET system, using the detection mold provided by the present invention, the method comprising:

[0018] After the detection mold is loaded with radioactive material and placed in the detection space of the PET system, PET data within a preset time length is obtained; the PET data includes full coincidence data and random coincidence data; the full coincidence data is converted into a first sinusoidal graph, and the random coincidence data is converted into a second sinusoidal graph; and a normalized correction coefficient of the PET system is determined based on the first sinusoidal graph, the second sinusoidal graph and the size data of the detection mold.

[0019] Optionally, determining the normalized correction coefficient of the PET system according to the first sinusoidal graph, the second sinusoidal graph and the size data of the detection mold includes: subtracting the first sinusoidal graph from the second sinusoidal graph to obtain a difference sinusoidal graph; determining multiple response lines according to the difference sinusoidal graph; determining the attenuation distance of each of the response lines according to the size data of the detection mold and system parameters of the PET system; and determining the normalized correction coefficient of the PET system according to the difference sinusoidal graph and the attenuation distance of each of the response lines.

[0020] Optionally, the acquiring of PET data within a preset time length includes: acquiring PET data within at least one radiation cycle; wherein, the activity of the radioactive material initially injected into the detection mold is a preset activity, and the radiation cycle is related to the preset activity; if the preset time length includes N radiation cycles, at the end of each of the first N-1 radiation cycles, the radioactive material is supplementally injected into the space of the detection mold so that the activity of the radioactive material in the detection mold is maintained at the preset activity, and N is an integer greater than 1.

[0021] In a third aspect, the present invention provides a device for detecting a normalized correction coefficient of a PET system, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method for detecting a normalized correction coefficient of a PET system provided by the present invention when executing the computer program.

[0022] In a fourth aspect, the present invention provides a PET system, comprising: the detection mold provided by the present invention and the detection equipment provided by the present invention.

[0023] In a fifth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the method for detecting the normalized correction coefficient of the PET system provided by the present invention is implemented.

[0024] The present invention provides a detection mold, method and device for a normalized correction coefficient of a PET system. The detection mold comprises an outer tube, an inner tube and an end plate. A ring-shaped cylindrical space for loading a solution is formed between the outer tube, the inner tube and the end plate. Since the ring-shaped cylindrical space has a cylindrical radiation surface and is relatively thin, the detection mold itself greatly reduces the attenuation and scattering of gamma photons, and detectors at different positions in the PET system can achieve uniform scanning, thereby improving the effectiveness of data collected by the detectors, reducing the amount of data collected by the detectors, and thereby improving the accuracy and efficiency of normalized correction of the PET system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A schematic diagram of a PET system provided by the present invention;

[0027] Figure 2 A schematic diagram of the lateral distribution of detectors in the PET system provided by the present invention;

[0028] Figure 3 A structural schematic diagram of a detection mold for the normalized correction coefficient of the PET system provided by the present invention;

[0029] Figure 4 A schematic diagram of the lateral distribution of the detection mold provided by the present invention after being placed in the detection space of the PET system;

[0030] Figure 5 A schematic diagram of the response line provided by the present invention;

[0031] Figure 6 A flow chart of a method for detecting a normalized correction coefficient of a PET system provided by the present invention;

[0032] Figure 7 A structural schematic diagram of a detection device for a normalized correction coefficient of a PET system provided by the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0034] It will be understood that the terms "first", "second", "third", "fourth", etc. (if any) in the embodiments of the present application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0035] The detection mold, method and device for the normalized correction coefficient of the PET system provided by the present invention can be applied to the scene of detecting the normalized correction coefficient of the PET system. Generally, the process of detecting the normalized correction coefficient of the PET system is as follows: a solution is injected into the detection mold and the detection mold is placed in the detection space of the PET system. The solution includes radioactive substances. The radioactive substance emits positrons, and annihilation occurs after the positrons and electrons meet, and the positrons and electrons disappear and a pair of gamma (γ) photons appear. The detector set in the PET system scans and detects the gamma photons and collects data. Afterwards, the collected data is processed to obtain the normalized correction coefficient of the PET system. It can be seen that when the detection mold is different, the scanning method of the detection mold is different, the amount of data collected is different, and then the accuracy, complexity and efficiency of detecting the normalized correction coefficient of the PET system are different.

[0036] In the related art, the detection mold is a flat mold, which can be rotated at multiple angles, and the detectors at different positions in the PET system scan and collect data. However, the amount of data collected is large, and the scanning angle is prone to misalignment, resulting in a complex processing method for normalization correction of the PET system and low accuracy.

[0037] Therefore, the present invention provides a detection mold for a normalized correction coefficient of a PET system, which has a circular cylindrical space for loading a solution, and detectors at different positions in the PET system can achieve uniform scanning, thereby improving the effectiveness of data collected by the detectors, reducing the amount of data collected by the detectors, and thus improving the efficiency of normalized correction of the PET system. Moreover, the space for loading the solution in the detection mold is a circular cylindrical shape, and after a pair of gamma photons are generated by the annihilation of positrons and electrons, the detection mold itself greatly reduces the attenuation and scattering of the gamma photons, thereby improving the accuracy of normalized correction of the PET system.

[0038] Next, a PET system is exemplified.

[0039] For example, Figure 1 A schematic diagram of the PET system provided by the present invention. Figure 1As shown, the PET system may include a test body 11, a test bench 13, and a processing device 14. The test body 11 includes a test space 12. During PET imaging, radioactive substances may be injected into a living body, and the living body lies on the test bench 13 and enters the test space 12. The detector in the PET system detects gamma photons and collects data. After that, the processing device 14 processes the collected data to form an image. When detecting the normalized correction coefficient of the PET system, radioactive substances may be injected into a detection mold, and the detection mold is placed on the test bench 13 and enters the test space 12. The detector in the PET system detects gamma photons and collects data. After that, the processing device 14 processes the collected data to obtain the normalized correction coefficient of the PET system.

[0040] For example, Figure 2 A schematic diagram of the lateral distribution of detectors in the PET system provided by the present invention. Figure 2 As shown, a transverse view of the PET system is shown, and multiple detectors 21 are evenly distributed in the circumferential direction of the test space 12. Assume that point 22 is the location where the positron and the electron annihilate, generating a pair of gamma photons, and the emission directions are respectively represented by line segments 23 and 24. Detector A can detect the gamma photons corresponding to line segment 23, and detector B can detect the gamma photons corresponding to line segment 24.

[0041] It should be noted that the present invention does not limit the names and structures of the test body 11, the test bench 13 and the test space 12, and does not limit the name and type of the processing device 14. For example, the test space 12 is also called a detection space. The processing device 14 is also called a detection device. The processing device 14 can be, for example, a processor or device with computing capabilities such as a computer.

[0042] Next, the concept involved in the present invention is explained.

[0043] 1. Horizontal and axial

[0044] For example, Figure 1 As shown, the depth direction along the test space 12 is called the axial direction, and the direction along the cross section of the test space 12 is called the lateral direction. The lateral direction is also called the radial direction.

[0045] 2. Axial field of view (AFOV)

[0046] A term in nuclear medicine that refers to the range that an imaging device can cover in the axial direction (Z axis).

[0047] 3. Sinogram

[0048] A term in nuclear medicine. A method of storing raw data from positron emission tomography. A set of projection matrices consisting of radial coordinates of the collected events arranged in rows, angular coordinates arranged in columns, and different coincident detection surfaces arranged in pages.

[0049] 4. Compliance detection and compliance events

[0050] Coincidence detection refers to a detection method that uses oppositely placed detectors to simultaneously (within the coincidence time window) detect annihilation radiation photon pairs to determine the direction of the annihilation event within the detection range.

[0051] A coincidence event refers to two simultaneously occurring related events detected using coincidence detection technology, which are counted as a coincidence.

[0052] In the embodiment of the present application, all coincidences refer to the collection of coincidence events detected by the PET system.

[0053] 5. Accidental coincidence

[0054] A term in nuclear medicine. The two photons detected coincide with each other coming from two independent annihilation events that occurred almost simultaneously.

[0055] In the embodiment of the present application, full matching includes random matching.

[0056] 6. Line of response (LOR)

[0057] The coincidence line, also called the response line, refers to the line between two detectors that simultaneously detect annihilation radiation photon pairs within the coincidence time window. For example, Figure 2 As shown, the entire line segment formed by line segment 23 and line segment 24 between detectors A and B is called the coincidence line.

[0058] The technical solution of the present application is described in detail below with reference to specific embodiments.

[0059] Figure 3 A schematic diagram of the structure of a detection mold for the normalized correction coefficient of the PET system provided by the present invention. The detection mold for the normalized correction coefficient of the PET system provided in this embodiment can be used to detect the normalized correction coefficient of the PET system. Figure 3 As shown, the detection model of the normalized correction coefficient of the PET system may include:

[0060] The outer tube 31 and the inner tube 32 have the same length, the inner diameter of the outer tube 31 is larger than the outer diameter of the inner tube 32, and the inner diameter of the inner tube 32 is larger than the lateral dimension corresponding to the field of view (FOV) of the PET system.

[0061] Two end plates 34. The two end plates 34 are connected to the two end surfaces of the outer tube 31 and the inner tube 32 respectively, and a cylindrical space 33 is formed between the inner wall of the outer tube 31, the outer wall of the inner tube 32 and the two end plates 34, and the space 33 is used to load radioactive substances.

[0062] At least two openings 35 and sealing components (not shown) respectively matched with the at least two openings 35. The openings 35 are located on the outer tube 31 or in the area corresponding to the space 33 on the end plate 34, and the at least two openings 35 are used to inject radioactive substances.

[0063] The detection mold provided in this embodiment may structurally include an outer tube 31, an inner tube 32 and an end plate 34. For example, Figure 4 A schematic diagram of the lateral distribution of the detection mold provided by the present invention after being placed in the detection space of the PET system. Figure 4 As shown, the outer diameter of the outer tube 31 is smaller than the inner diameter of the test space 12 (or detection space) of the PET system, so that the detection mold can be placed inside the test space 12. The inner diameter of the outer tube 31 is larger than the outer diameter of the inner tube 32, and the inner diameter of the inner tube 32 is larger than the maximum transverse dimension of the detection field of view 41 of the PET system. Between the outer tube 31 and the inner tube 32 is a circular cylindrical space 33. Since the circular cylindrical space 33 has a cylindrical radiation surface, the circular cylindrical space 33 can uniformly radiate gamma photons after the radioactive material is injected. Therefore, the detector in the PET system can achieve uniform scanning, and the collected data is more effective.

[0064] Since the thickness of the annular cylindrical space 33 is relatively thin, the detection mold itself greatly reduces the attenuation and scattering of gamma photons. For example, Figure 5 A schematic diagram of the response line provided by the present invention. Figure 5As shown, it is assumed that point 51 is the position where the positron and the electron annihilate, and a pair of gamma photons are generated, and the emission directions are represented by line segments 52 and 53, respectively. Detector A can detect the gamma photons corresponding to line segment 52, and detector B can detect the gamma photons corresponding to line segment 53. For the gamma photons corresponding to line segment 52, the radiation path needs to pass through part of the radioactive solution and the outer tube 31 in the space 33, as can be seen from the bold part on line segment 52. For the gamma photons corresponding to line segment 53, the radiation path needs to pass through the radioactive solution, the outer tube 31 and the two layers of the inner tube 32 in the space 33, as can be seen from the bold part on line segment 53. For the response line formed by line segments 52 and 53, the attenuation distance of the response line can include the solution distance of the radioactive solution in the space 33 through which the response line passes, the wall thickness of the inner tube 32 and the wall thickness of the outer tube 31. Since the thickness of the space 33 and the wall thickness of the inner tube 32 and the outer tube 31 are relatively small, the detection mold itself greatly reduces the attenuation and scattering of gamma photons, improves the accuracy of the data collected by the detector in the PET system, and further improves the accuracy of the normalization correction of the PET system.

[0065] Moreover, since the space 33 is in the shape of a circular cylinder and contains less radioactive solution, the amount of data collected by the detector in the PET system is reduced, the difficulty and workload of post-processing data are reduced, and the efficiency of normalization correction of the PET system is improved.

[0066] When the detection mold provided in this embodiment is used, the radioactive material is first injected into the space 33 through the at least two openings 35. Usually, a solution containing the radioactive material is injected into the space 33. Among them, at least one opening 35 of the at least two openings 35 can be used to inject the radioactive material, and at least one opening 35 of the at least two openings 35 can maintain the pressure inside and outside the space 33 when injecting the radioactive material, so that the radioactive material is smoothly injected into the space 33. Then, the detection mold is placed in the detection space of the PET system so that the detector of the PET system can collect data.

[0067] It should be noted that this embodiment does not limit the materials of the outer tube 31, the inner tube 32 and the end plate 34. Optionally, the materials used for the outer tube 31, the inner tube 32 and the end plate 34 should minimize the impact on gamma photon radiation. For example, the material can be acrylic.

[0068] It should be noted that this embodiment does not limit the shape of the end plate 34. Optionally, in one implementation, the end plate 34 may be annular, the size of the large circle of the annular ring may be the same as the size of the outer tube 31, and the size of the small circle of the annular ring may be the same as the size of the inner tube 32. Optionally, in another implementation, the end plate 34 may be circular, and the size of the circular circle may be the same as the size of the outer tube 31.

[0069] It should be noted that the present embodiment does not limit the connection method of the outer tube 31 and the inner tube 32 with the end plate 34. For example, an adhesive may be used for bonding. Optionally, in order to improve the strength of the detection mold, one of the two end plates 34, the outer tube 31 and the inner tube 32 may be integrally formed.

[0070] Optionally, the lengths of the outer tube 31 and the inner tube 32 are greater than the length of the axial field of view of the PET system.

[0071] In this implementation, after the detection mold is placed in the detection space of the PET system, both ends of the detection mold will extend out a portion compared to the axial field of view of the PET system. In this way, it is ensured that the radioactive material in the detection mold can evenly irradiate all detectors in the PET system, thereby achieving uniform scanning of all detectors in the PET system and improving the accuracy of the normalization correction of the PET system.

[0072] Optionally, the wall thickness of the outer tube 31 and the inner tube 32 are both less than or equal to 5 mm.

[0073] In this implementation, the wall thickness of the outer tube and the inner tube can be set as small as possible, thereby reducing the radiation impact on gamma photons and improving the accuracy of normalization correction of the PET system.

[0074] Optionally, the wall thickness of the outer tube 31 and the inner tube 32 may be related to the length of the outer tube 31 and the inner tube 32. When the length of the outer tube 31 and the inner tube 32 is long, in order to ensure the strength of the detection mold, the wall thickness of the outer tube 31 and the inner tube 32 may be larger. When the length of the outer tube 31 and the inner tube 32 is short, the wall thickness of the outer tube 31 and the inner tube 32 may be smaller. Optionally, when the length of the outer tube 31 and the inner tube 32 is greater than or equal to 15 cm, the wall thickness of the outer tube 31 and the inner tube 32 may be set to 5 mm. When the length of the outer tube 31 and the inner tube 32 is less than 15 cm, the wall thickness of the outer tube 31 and the inner tube 32 may be less than 5 mm, for example, 2 mm.

[0075] Optionally, the wall thickness of the end plate 34 may be less than or equal to 5 mm.

[0076] In this implementation, the wall thickness of the end plate can be set as small as possible, thereby reducing the radiation impact on gamma photons and improving the accuracy of normalization correction of the PET system.

[0077] Optionally, the lateral thickness of the space 33 may be less than or equal to 5 mm.

[0078] The transverse thickness of the space refers to the difference between the size of the large circle and the size of the small circle of the annular space, which can also be called the thickness of the space. In this implementation, the transverse thickness of the space can be set as small as possible, thereby reducing the radiation impact on gamma photons and reducing the amount of collected data, thereby improving the accuracy and efficiency of the normalization correction of the PET system.

[0079] Optionally, the wall thickness of the outer tube 31 and the inner tube 32 may be the same.

[0080] Optionally, the wall thicknesses of the outer tube 31 , the inner tube 32 and the end plate 34 may all be the same.

[0081] Optionally, in this embodiment, the number, position and shape of at least two openings 35 in the detection mold are not limited. For example, at least two openings 35 are located on the outer tube 31; or, at least two openings 35 are located on the end plate 34; or, a part of at least two openings 35 is located on the outer tube 31, and the other part is located on the end plate 34. Optionally, for the openings 35 located on the end plate 34, all the openings 35 can be located on one end plate 34, or, all the openings 35 are located on two end plates 34 respectively. Optionally, for the openings 35 located on the end plate 34, they can be located in the area corresponding to the space 33 on the two end plates 34. For example. If the shape of the end plate 34 is annular, the annular ring and the outer tube 31 and the inner tube 32 enclose the space 33 of the annular cylinder, and the opening 35 is located in the annular ring. If the shape of the end plate 34 is circular, the opening 35 can be located in the area between the outer tube and the inner tube on the end plate 34.

[0082] For example, Figure 3 As shown, the number of the at least two openings 35 is two, and the two openings 35 are located on the same end plate 34 and in the area on the end plate 34 corresponding to the space 33 .

[0083] Optionally, the opening 35 may be a threaded hole, and the sealing assembly may include a threaded fastener and a sealing ring. Optionally, the threaded fastener may include any one of the following: a screw, a bolt, or a screw. In this embodiment, the shape and material of the threaded fastener and the sealing ring are not limited. For example, the threaded fastener uses acrylic material.

[0084] Optionally, the specification of the threaded hole may be M5.

[0085] Optionally, the PET system may further include a motion component, and the detection mold may be placed on the motion component. The motion component is used to drive the mold to move linearly in the detection space of the PET system along the axial direction of the detection space.

[0086] In this implementation, the motion component can drive the detection mold to move linearly in the detection space of the PET system to improve the detection intensity.

[0087] It can be seen that the detection mold for the normalized correction coefficient of the PET system provided in this embodiment has a circular cylindrical space for loading radioactive materials, and the detectors at different positions in the PET system can achieve uniform scanning, which improves the effectiveness of the detector data collection, reduces the amount of data collected by the detector, and thus improves the efficiency of the normalized correction of the PET system. Moreover, since the space for loading radioactive materials is a circular cylindrical space, after the positron and electron annihilate to produce a pair of gamma photons, the detection mold itself greatly reduces the attenuation and scattering of the gamma photons, thereby improving the accuracy of the normalized correction of the PET system.

[0088] Figure 6 A flow chart of the detection method of the normalized correction coefficient of the PET system provided by the present invention. The detection method of the normalized correction coefficient of the PET system provided by this embodiment can be performed by a detection device of the normalized correction coefficient of the PET system. Figure 3 The embodiment shown provides a detection mold for the normalized correction coefficient of the PET system, and the detection mold is loaded with radioactive material and placed in the detection space of the PET system. Figure 6 As shown, the detection method of the normalized correction coefficient of the PET system may include:

[0089] S601, after the detection mold is loaded with radioactive material and placed in the detection space of the PET system, PET data within a preset time period is obtained, wherein the PET data includes full coincidence data and random coincidence data.

[0090] Specifically, the detection mold is loaded with radioactive material, usually a solution containing the radioactive material. This embodiment does not limit the type of radioactive material, the activity and the composition of the solution. For example, the radioactive material can be fluorodeoxyglucose (FDG), the activity can be 0.5mCi, and the solution can be a solution formed by mixing FDG and water. During detection, FDG with an activity of about 0.5mCi can be mixed with clean water, injected into the annular columnar space through the opening (such as a threaded hole) on the detection mold, tighten the screw with the sealing ring, and then put it into the radial and axial center of the PET system to evenly irradiate the detector in the PET system. Correspondingly, the detector in the PET system collects relevant data.

[0091] Among them, the full matching data includes random matching data.

[0092] Among them, this embodiment does not limit the specific value of the preset duration. The preset duration may be related to the radiation time of the radioactive substance. Optionally, the preset duration may include one or more half-lives of the radioactive substance. The half-life refers to the radiation duration when the radioactivity is 1 / 2 of the initial activity. For example, for an FDG solution with an initial activity of about 0.5 mCi, the half-life is about 110 minutes.

[0093] S602: convert the full coincidence data into a first sinusoidal graph, and convert the random coincidence data into a second sinusoidal graph.

[0094] S603, determining a normalized correction coefficient of the PET system according to the first sinusoidal graph, the second sinusoidal graph and the size data of the detection mold.

[0095] The dimension data of the detection mold may include but are not limited to: the wall thickness of the outer tube, the wall thickness of the inner tube, the thickness of the end plate and the transverse thickness of the annular cylindrical space in the detection mold.

[0096] It can be seen that the detection method of the normalized correction coefficient of the PET system provided in this embodiment uses the detection mold of the normalized correction coefficient of the PET system to obtain the normalized correction coefficient of the PET system. Since the detection mold of the normalized correction coefficient of the PET system has a circular cylindrical space for loading radioactive materials, the detectors at different positions in the PET system can achieve uniform scanning, which improves the effectiveness of the detector data collection, reduces the amount of data collected by the detector, and also reduces the amount of data processed by the detection equipment, thereby improving the efficiency of the normalized correction of the PET system. Moreover, since the space for loading radioactive materials is a circular cylindrical space, after the positron and electron annihilate to produce a pair of gamma photons, the detection mold itself greatly reduces the attenuation and scattering of the gamma photons, thereby improving the accuracy of the normalized correction of the PET system.

[0097] Optionally, in S601, obtaining PET data within a preset time period may include:

[0098] PET data is acquired for at least one radiation cycle.

[0099] The activity of the radioactive material initially injected into the detection mold is the preset activity, and the radiation cycle is related to the preset activity. If the preset duration includes N radiation cycles, at the end of each radiation cycle in the first N-1 radiation cycles, the radioactive material is additionally injected into the space of the detection mold to keep the activity of the radioactive material in the detection mold at the preset activity, where N is an integer greater than 1.

[0100] In this implementation, the preset duration includes at least one radiation cycle, and this embodiment does not limit the value of the radiation cycle. For example, the radiation cycle may be the half-life of the radioactive substance. For another example, the radiation cycle may be the radiation duration when the radioactivity is 1 / 4 of the initial activity.

[0101] This embodiment does not limit the value of the preset activity.

[0102] Below, taking the radiation cycle as the half-life, the radioactive substance as FDG with a preset activity of 0.5 mCi, and a half-life of 110 minutes as an example, the preset time length and the implementation method of obtaining PET data within the preset time length are explained.

[0103] Assuming that the preset time includes a half-life, for example, 2 hours, after the detection mold is loaded with FDG with an activity of 0.5 mCi and placed in the detection space of the PET system, 2 hours of PET data can be obtained.

[0104] Assume that the preset duration includes 3 half-lives, for example, 6 hours. After the detection mold is loaded with FDG with an activity of 0.5mCi and placed in the detection space of the PET system, 2 hours of PET data can be obtained first. At this time, the activity of FDG in the detection mold is reduced. FDG is supplemented by injecting it into the annular cylindrical space through the openings (for example, threaded holes) on the detection mold, so that the activity of FDG in the detection mold is approximately maintained at the preset activity, i.e., 0.5mCi. Tighten the screws with the sealing ring, and then place the detection mold in the radial and axial center of the PET system, continue to evenly irradiate the detector in the PET system, and continue to obtain 2 hours of PET data. After 2 hours, FDG is supplemented again, and a total of 6 hours of PET data can be obtained.

[0105] Optionally, in S603, determining a normalized correction coefficient of the PET system according to the first sinusoidal graph, the second sinusoidal graph and the size data of the detection mold may include:

[0106] The first sinogram is subtracted from the second sinogram to obtain a difference sinogram.

[0107] Multiple response lines are determined from the difference sinusoidal graph.

[0108] The attenuation distance of each response line is determined according to the size data of the detection mold and the system parameters of the PET system.

[0109] The normalized correction coefficient of the PET system is determined based on the difference sinusoidal graph and the attenuation distance of each response line.

[0110] Specifically, the first sinusoidal graph can be marked as S prompt , the second sinogram can be marked as S random, the difference sinusoidal graph can be marked as S RC The difference sinusoidal graph can be obtained by formula (1). By subtracting the first sinusoidal graph from the second sinusoidal graph to obtain the difference sinusoidal graph, the influence of random coincidence data on the normalization correction coefficient of the detection PET system is eliminated, and the accuracy of the normalization correction of the PET system is further improved.

[0111]

[0112] Afterwards, the attenuation distance of each response line can be determined based on the size data of the detection mold and the system parameters of the PET system. Optionally, the system parameters of the PET system may include but are not limited to the diameter of the detector ring, the lateral diameter of the FOV, etc. The attenuation distance may include the solution distance (marked as L) that the response line passes through. act ) and the distance between the inner tube and the outer tube through which the response line passes (marked as L PMMA ). Among them, the solution distance L act and distance L PMMA S actC It is related to the location where the positron and electron annihilate and the direction of the gamma photon radiation.

[0113] Optionally, in one implementation, determining a normalized correction coefficient of the PET system according to the difference sinusoidal graph and the attenuation distance of each response line may include:

[0114] Using formula (2), according to the difference sinusoidal graph S RC The distance L of the solution through which the response line passes act The response line is corrected by linear activity to obtain the corrected sinusoidal diagram (marked as S actC ).

[0115] Using formula (3), according to the corrected sinusoidal graph, the distance L of the solution that the response line passes through act , distance L PMMA The attenuation correction is performed with the attenuation coefficient μ to obtain the normalized correction coefficient of the PET system (marked as S norm ).

[0116]

[0117]

[0118] Wherein, in formula (3), e is a natural constant.

[0119] It should be noted that the present embodiment does not limit the value of the attenuation coefficient, which may be related to the materials of the radioactive solution and the detection mold. For example, the attenuation coefficients of the aqueous solution and the acrylic material to 511keV gamma rays are substantially the same, and the attenuation coefficient may be set according to the attenuation coefficient of water μ=0.096 / cm.

[0120] It can be seen that the detection method of the normalized correction coefficient of the PET system provided in this embodiment uses the detection mold of the normalized correction coefficient of the PET system to obtain the normalized correction coefficient of the PET system. Since the detection mold reduces the attenuation and scattering of gamma photons, the accuracy and efficiency of the normalized correction of the PET system are improved. Therefore, by processing the data collected based on the detection mold, the normalized correction coefficient of the PET system is obtained, which improves the accuracy and efficiency of the normalized correction of the PET system.

[0121] Figure 7 A schematic diagram of the structure of a detection device for the normalized correction coefficient of a PET system provided by the present invention. Figure 7 As shown, the detection device for the normalized correction coefficient of the PET system provided in this embodiment may include a processor 702, a memory 704 and a communication interface 703 connected to a system bus 701. The processor 702 is used to provide computing and control capabilities. The memory 704 includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface 703 of the detection device is used to communicate with other devices. When the computer program is executed by the processor 702, the detection method for the normalized correction coefficient of the PET system provided by the present invention is implemented.

[0122] Those skilled in the art will understand that Figure 7 The structure shown in the figure is only a block diagram of a part of the structure related to the scheme of the present application, and does not constitute a limitation on the detection device of the normalized correction coefficient of the PET system provided in the present application. The specific detection device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0123] It should be clear that the process of the processor executing the computer program in the embodiment of the present application is consistent with the execution process of each step in the above method, and the details can be found in the description above.

[0124] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the method for detecting the normalized correction coefficient of the PET system provided in the above method embodiment of the present application can be implemented.

[0125] It should be clear that the process of the processor executing the computer program in the embodiment of the present application is consistent with the execution process of each step in the above method, and the details can be found in the description above.

[0126] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0127] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0128] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A method for detecting a normalized correction coefficient of a positron emission tomography (PET) system, It is characterized in that Applied to the detection mold, the detection mold comprises: An outer tube and an inner tube of the same length, wherein the inner diameter of the outer tube is larger than the outer diameter of the inner tube, and the inner diameter of the inner tube is larger than the lateral dimension corresponding to the field of view FOV of the PET system; Two end plates; the two end plates are connected to two end surfaces of the outer tube and the inner tube respectively, and an annular cylindrical space is formed between the inner wall of the outer tube, the outer wall of the inner tube and the two end plates, and the space is used to load radioactive materials; at least two openings and sealing components respectively matched with the at least two openings; the openings are located on the outer tube or in an area on the end plate corresponding to the space, and the at least two openings are used to inject the radioactive material; The detection method comprises: after the detection mold is loaded with radioactive material and placed in the detection space of the PET system, obtaining PET data within a preset time period; the PET data comprises full coincidence data and random coincidence data; Converting the full coincidence data into a first sinusoidal graph, and converting the random coincidence data into a second sinusoidal graph; Determining a normalized correction coefficient of the PET system according to the first sinusoidal graph, the second sinusoidal graph and the size data of the detection mold; The step of determining a normalized correction coefficient of the PET system according to the first sinusoidal graph, the second sinusoidal graph and the size data of the detection mold comprises: Subtracting the first sinusoidal graph from the second sinusoidal graph to obtain a difference sinusoidal graph; determining a plurality of response lines according to the difference sinusoidal graph; Determining the attenuation distance of each of the response lines according to the size data of the detection mold and the system parameters of the PET system; A normalized correction coefficient of the PET system is determined according to the difference sinusoidal graph and the attenuation distance of each of the response lines.

2. The detection method according to claim 1, It is characterized in that The lengths of the outer tube and the inner tube are greater than the length of the axial field of view of the PET system.

3. The detection method according to claim 1, It is characterized in that The wall thicknesses of the outer tube, the inner tube and the end plate are all less than or equal to 5 mm.

4. The detection method according to claim 1, It is characterized in that The transverse thickness of the space is less than or equal to 5 mm.

5. The detection method according to any one of claims 1 to 4, It is characterized in that The at least two openings are located in areas of the two end plates corresponding to the spaces.

6. The detection method according to any one of claims 1 to 4, It is characterized in that The end plate is annular or circular.

7. The detection method according to any one of claims 1 to 4, wherein the opening is a threaded hole, and the sealing assembly comprises a threaded fastener and a sealing ring.

8. The method according to claim 1, It is characterized in that The step of obtaining PET data within a preset time period includes: Acquiring PET data within at least one radiation cycle; Among them, the activity of the radioactive material initially injected into the detection mold is a preset activity, and the radiation cycle is related to the preset activity; if the preset duration includes N radiation cycles, at the end of each of the first N-1 radiation cycles, the radioactive material is supplementarily injected into the space of the detection mold to keep the activity of the radioactive material in the detection mold at the preset activity, and N is an integer greater than 1.

9. A device for detecting the normalization correction coefficient of a positron emission tomography imaging PET system, It is characterized in that include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method according to any one of claims 1 to 8 when executing the computer program.

10. A positron emission tomography (PET) system, It is characterized in that include: A detection mold using the detection method described in any one of claims 1 to 8 and a detection device described in claim 9.

11. A computer-readable storage medium having a computer program stored thereon, It is characterized in that When the computer program is executed by a processor, the method according to any one of claims 1 to 8 is implemented.

Images