Medical image registration parameter acquisition method and system, imaging method and medium

Abstract

The invention provides a medical image registration parameter acquisition method and system, an imaging method of a PET-CT (positron emission tomography-computed tomography) system and a medium. The medical image registration parameter acquisition method comprises the following steps: firstly, placing a registration motif in a field of view of CT imaging equipment, and acquiring a CT reconstructed image of the registration motif; wherein the registration die body does not contain a radioactive source; then, the registration die body is placed in the view field of PET imaging equipment, and background coincidence event data are collected; and finally, according to the CT reconstruction image and the background coincidence event data, registration parameters are obtained, and the registration parameters represent the mapping relation that CT data collected by the CT imaging equipment are aligned to PET data collected by the PET imaging equipment. A registration die body does not need to be poured or a solid registration source does not need to be prepared, the operation process can be simplified, manpower and material resources are saved, and registration efficiency is improved; in addition, the radiation damage of a radioactive source to operators can be reduced, and the hardware requirement for PET-CT imaging equipment is remarkably lowered.

Description

Technical Field

[0001] The present invention relates to the technical field of medical image processing, and in particular to a method and system for acquiring medical image registration parameters, an imaging method, electronic equipment and a medium of a PET-CT system. Background Art

[0002] Positron emission computed tomography-computer tomography (PET-CT) can obtain PET images with functional information and CT images with fine anatomical information. The fusion of PET and CT images can accurately locate the lesion and improve the accuracy of disease diagnosis. However, high-quality PET images often rely on correct physical correction, including attenuation correction. In the related art, the attenuation image is generally obtained by converting and registering the CT image. Specifically, the registration process first requires the perfusion of a radioactive source into a registration phantom (such as a water phantom), or the use of a solid registration source, and the registration phantom is scanned and reconstructed using a CT imaging device and a PET imaging device to obtain an attenuation image; then the CT reconstructed image and the PET reconstructed image are registered and calculated to obtain the mapping relationship between the CT image reconstruction coordinate system and the PET image reconstruction coordinate system. The above process requires experienced operators to make a membrane containing a radioactive source, which is time-consuming, labor-intensive, inefficient and costly on the one hand, and on the other hand, the radioactive source is radioactive and can cause harm to the health of the operator. Moreover, the registration method has the defect of high requirements on operators and PET imaging equipment. For example, for PET imaging equipment without external radiation source installation device and movement device, it is impossible to obtain attenuation images through external radiation sources.

[0003] It should be noted that the information disclosed in the background technology section of the invention is only intended to deepen the understanding of the general background technology of the invention, and should not be regarded as an admission or suggestion in any form that the information constitutes prior art already known to those skilled in the art. Summary of the invention

[0004] The purpose of the present invention is to provide a method and system for obtaining medical image registration parameters, an imaging method, an electronic device and a medium for a PET-CT system, in order to address one or more of the problems existing in the prior art of PET-CT imaging equipment in the image registration process, such as low efficiency, high requirements for operators and equipment, and radiation damage to operators. The present invention can simplify the registration process, improve the registration efficiency, and effectively reduce the radiation damage to operators while ensuring the registration accuracy, thereby saving manpower and material costs.

[0005] To achieve the above object, the present invention is implemented through the following technical solutions: a method for obtaining medical image registration parameters, used in a PET-CT system, wherein the PET-CT system includes a CT imaging device and a PET imaging device, and the method for obtaining medical image registration parameters includes:

[0006] Placing a registration phantom within the field of view of the CT imaging device to obtain a CT reconstructed image of the registration phantom; wherein the registration phantom does not contain a radiation source;

[0007] Placing the registration phantom within the field of view of a PET imaging device to collect background coincidence event data;

[0008] According to the CT reconstructed image and the background coincidence event data, a registration parameter is acquired, wherein the registration parameter represents a mapping relationship for aligning the CT data acquired by the CT imaging device to the PET data acquired by the PET imaging device.

[0009] Optionally, background radiation data from a detector crystal of the PET imaging device is collected, and the background coincidence event data is obtained based on the background radiation data.

[0010] Optionally, the background coincidence event data is acquired according to the arrival energy and arrival time of β rays and γ rays in the background radiation data.

[0011] Optionally, the background coincident event data is subjected to denoising processing to obtain denoised background coincident event data; and registration parameters are acquired according to the CT reconstructed image and the denoised background coincident event data.

[0012] Optionally, performing noise reduction processing on the background coincidence event data includes:

[0013] Merging at least two original response lines into a combined response line, and acquiring the background coincidence event data after noise reduction according to the background coincidence event data received by at least one of the combined response lines;

[0014] Alternatively, the original background coincidence event data received by the original response line is smoothed to obtain the background coincidence event data after noise reduction.

[0015] Optionally, a first attenuation image in the coordinate system of the CT imaging device is acquired according to the CT reconstructed image, and a second attenuation image in the coordinate system of the PET imaging device is acquired according to the background coincidence event data;

[0016] Iteratively updating the second attenuation image using a maximum likelihood function estimation method according to the background coincidence event data, the first attenuation image, and the estimated registration parameters until a preset end condition is met;

[0017] The estimated registration parameter corresponding to the maximum likelihood function is used as the registration parameter.

[0018] Optionally, during the iterative updating of the second attenuation image, an optimization method is used to obtain the estimated registration parameters.

[0019] In order to achieve the above object, the present invention further provides a medical image imaging system, the medical image imaging system comprising:

[0020] A PET imaging system configured to acquire a CT reconstructed image of a registration phantom placed within its field of view; wherein the registration phantom does not contain a radiation source;

[0021] a CT imaging system configured to acquire background coincidence event data when the registration phantom is positioned within its field of view;

[0022] The registration parameter acquisition device is configured to acquire the registration parameters according to the CT reconstructed image and the background coincidence event data, wherein the registration parameters represent the mapping relationship of aligning the CT data collected by the CT imaging device to the PET data collected by the PET imaging device.

[0023] In order to achieve the above object, the present invention further provides an imaging method of a PET-CT system, wherein the PET-CT system comprises a CT imaging device and a PET imaging device, and the imaging method comprises:

[0024] Acquire PET data of the detected object within the field of view of the PET imaging device;

[0025] Acquire CT data of the detected object within the field of view of the CT imaging device;

[0026] Acquire registration parameters, wherein the registration parameters represent a mapping relationship between aligning the CT data acquired by the CT imaging device to the PET data acquired by the PET imaging device, and the registration parameters are obtained based on the CT calibration data and background coincidence event data respectively acquired by the PET-CT system using a registration phantom;

[0027] aligning the CT data to the PET data according to the registration parameters to obtain an attenuation map;

[0028] The PET data is reconstructed according to the attenuation map to obtain a target PET image.

[0029] In order to achieve the above-mentioned purpose, the present invention also provides an electronic device, which includes a processor and a memory, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the medical image registration parameter acquisition method described in any one of the above items is implemented.

[0030] In order to achieve the above-mentioned object, the present invention further provides a readable storage medium, in which a computer program is stored. When the computer program is executed by a processor, any of the above-mentioned methods for obtaining medical image registration parameters is implemented.

[0031] Compared with the prior art, the medical image registration parameter acquisition method, system, PET-CT system imaging method, electronic device and medium provided by the present invention have the following advantages:

[0032] The medical image registration parameter acquisition method provided by the present invention is used in a PET-CT system having a CT imaging device and a PET imaging device. The medical image registration parameter acquisition method first places a registration phantom in the field of view of the CT imaging device to acquire a CT reconstructed image of the registration phantom; wherein the registration phantom does not contain a radioactive source; then the registration phantom is placed in the field of view of the PET imaging device to collect background coincidence event data; finally, registration parameters are acquired according to the CT reconstructed image and the background coincidence event data, wherein the registration parameters represent a mapping relationship of aligning the CT data acquired by the CT imaging device to the PET data acquired by the PET imaging device. Therefore, the medical image configuration parameter acquisition method provided by the present invention utilizes the spontaneous background radiation of the PET imaging device (exemplarily, the detector of the PET imaging device is an LSO or LYSO scintillation crystal detector) as a transmission source after energy information screening to obtain the attenuation image of the registration phantom, without the need to perfuse the registration phantom or prepare a solid registration source, thereby simplifying the operation process, not only saving manpower and material resources, but also improving the registration efficiency, laying a solid foundation for the rapid registration of PET reconstructed images and CT reconstructed images; and can reduce the radiation damage of the radiation source to the operator; further, since there is no need to perfuse the registration phantom or prepare a solid registration source, the hardware requirements for the PET-CT imaging device are significantly reduced, and the present invention can be applied to PET imaging devices without external radiation source installation devices and motion devices; further, the present invention does not need to increase any hardware cost, has good applicability and is easy to deploy and implement.

[0033] Since the medical image imaging system, imaging method, electronic device and storage medium of the PET-CT system provided by the present invention belong to the same inventive concept as the medical image registration parameter acquisition method provided by the present invention, the medical image imaging system, imaging method, electronic device and storage medium of the PET-CT system provided by the present invention at least have all the advantages of the medical image registration parameter acquisition method provided by the present invention. For details, please refer to the relevant description of the beneficial effects of the above-mentioned medical image registration parameter acquisition method, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1A schematic diagram of the overall process of a method for obtaining medical image registration parameters provided by one embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the decay energy levels of Lu-176;

[0036] Figure 3 Schematic diagram of the process of identifying background coincidence events in a PET imaging device;

[0037] Figure 4 A schematic diagram of the structure of a medical imaging system provided by another embodiment of the present invention;

[0038] Figure 5 A schematic flow chart of an imaging method of a PET-CT system provided in yet another embodiment of the present invention;

[0039] Figure 6 A schematic block diagram of an electronic device provided in yet another embodiment of the present invention.

[0040] The reference numerals are as follows:

[0041] PET imaging device-100, CT imaging device-200, registration parameter acquisition device-300;

[0042] Processor-410, communication interface-420, memory-430, communication bus-440. DETAILED DESCRIPTION

[0043] The following is a further detailed description of the medical image registration parameter acquisition method, system, imaging method of PET-CT system, electronic device and medium proposed by the present invention in conjunction with the accompanying drawings. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the drawings are in a very simplified form and all use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purposes, features and advantages of the present invention more obvious and easy to understand, please refer to the accompanying drawings. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Any modification of the structure, change of the proportional relationship or adjustment of the size, under the same or similar conditions as the effects that can be produced by the present invention and the purposes that can be achieved, should still fall within the scope of the technical content disclosed by the present invention. The specific design features of the present invention disclosed herein, including, for example, specific dimensions, directions, positions and shapes, will be determined in part by the specific environment to be applied and used. Also, in the embodiments described below, sometimes the same reference numerals are used in common between different figures to represent the same parts or parts with the same functions, and their repeated descriptions are omitted. In this specification, similar reference numerals and letters are used to represent similar items, so once an item is defined in one figure, it does not need to be further discussed in subsequent figures. In addition, if the method described herein includes a series of steps, the order of these steps presented herein is not necessarily the only order in which these steps can be performed, and some of the steps described may be omitted and / or some other steps not described herein may be added to the method.

[0044] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements. The singular forms "a", "an" and "the" include plural objects, the term "or" is generally used in a sense including "and / or", the term "several" is generally used in a sense including "at least one", and the term "at least two" is generally used in a sense including "two or more". In addition, the terms "first", "second" and "third" are used for descriptive purposes only and are not to be understood as indicating or suggesting relative importance or implicitly indicating the number of the indicated technical features.

[0045] It should be noted that the medical image registration parameter acquisition method and the imaging method of the PET-CT system provided by the present invention can be applied to the medical image imaging system and electronic device provided by the present invention, wherein the electronic device can be a terminal, etc., and the terminal can be a mobile device, a tablet computer, a laptop computer, a desktop computer, or other devices with input and / or output functions, and is a hardware device with various operating systems.

[0046] One embodiment of the present invention provides a method for obtaining medical image registration parameters, which is used in a PET-CT system, wherein the PET-CT system includes a CT imaging device and a PET imaging device. Figure 1 , Figure 1 The overall flow diagram of a method for obtaining medical image registration parameters provided by one embodiment of the present invention is as follows. The method for obtaining medical image registration parameters comprises:

[0047] S100: placing a registration phantom within the field of view of the CT imaging device, and acquiring a CT reconstructed image of the registration phantom; wherein the registration phantom does not contain a radiation source;

[0048] S200: placing the registration phantom within the field of view of a PET imaging device to collect background coincidence event data;

[0049] S300: Acquire registration parameters according to the CT reconstructed image and the background coincidence event data, wherein the registration parameters represent a mapping relationship between aligning the CT data acquired by the CT imaging device to the PET data acquired by the PET imaging device.

[0050] It can be seen that the medical image configuration parameter acquisition method provided in this embodiment uses the spontaneous background radiation of the PET imaging device (exemplarily, the detector of the PET imaging device is an LSO or LYSO scintillation crystal detector) as a transmission source after energy information identification to obtain the attenuation image of the registration phantom. There is no need to perfuse the registration phantom or prepare a solid registration source, thereby simplifying the operation process, which not only saves manpower and material resources, improves the registration efficiency, and lays a solid foundation for the rapid registration of PET reconstructed images and CT reconstructed images; but also can reduce the radiation damage of the radiation source to the operator; further, since there is no need to perfuse the registration phantom or prepare a solid registration source, the hardware requirements for the PET-CT imaging device are significantly reduced, and the present invention can be applied to PET imaging devices without external radiation source installation devices and motion devices; further, the present invention does not need to increase any hardware cost, has good applicability and is easy to deploy and implement.

[0051] It should be noted that, as can be understood by those skilled in the art, the present invention does not require a specific shape of the registration phantom. For example, the radiation source phantom can be a uniform axially symmetrical phantom. For example, in some embodiments, the registration phantom can be a uniform cylindrical shape. In other embodiments, the registration phantom can be a ring source. In other embodiments, the registration phantom can also be a spherical shape. These are not listed one by one.

[0052] In addition, it should be particularly noted that those skilled in the art should be able to understand that the method for obtaining medical image registration parameters provided by the present invention does not impose any limitation on its use scenario. For example, it can be performed before each PET image scan, or it can be performed irregularly as needed, and of course, it can also be performed only during regular maintenance of the PET-CT system. The present invention does not impose any limitation on this.

[0053] Specifically, as those skilled in the art can understand, in the actual operation process, step S100 is specifically as follows: first, the registration phantom is placed in the field of view (FOV) of the CT imaging device, and then the registration phantom is scanned, and the obtained CT scan data is reconstructed to obtain a CT reconstructed image. It should be noted that the present invention does not limit the scanning method for obtaining CT scan data, and any related technology including but not limited to sequential scanning (also known as axial scanning mode) and spiral scanning (also known as volume scanning) known to those skilled in the art can be used. Further, the present invention does not limit the reconstruction method for obtaining the CT reconstructed image, and any related technology including but not limited to the back projection method, iterative reconstruction algorithm, and analytical method (including filtered back projection method and Fourier transform method) can be used as those skilled in the art are well known.

[0054] The PET imaging device includes a plurality of detectors, and the specific number of the detectors is not specifically limited in the embodiment of the present invention. The axial field of view of the PET imaging device is a space in which a radiation source phantom can be placed and photons generated by the radiation source can be collected.

[0055] Preferably, in some exemplary embodiments, collecting background coincidence event data in step S200 specifically includes: collecting background radiation data from a detector crystal of the PET imaging device, and obtaining the background coincidence event data based on the background radiation data.

[0056] Therefore, the medical image registration parameter acquisition method provided in this embodiment, its background coincidence event data comes from the spontaneous background radiation data of the detector crystal of the PET imaging device, that is, the radiation signal received by the PET imaging device is generated by the background radiation, thereby laying a foundation for obtaining the registration parameters even when the registration model does not contain a radiation source.

[0057] For example, common PET imaging devices use LSO or LYSO crystals as scintillating crystals, which contain the isotope Lu-176 and therefore have an intrinsic radioactivity phenomenon that can generate spontaneous background radiation. For details, see Figure 2 , Figure 2 The diagram below is the decay energy level diagram of Lu-176. Figure 2 As shown in the figure, the decay of Lu-176 includes simultaneous β decay and cascade γ decay, the maximum energy of β decay is 589keV, and the energy of γ decay is 307keV, 202keV and 88keV. The background event is the response of the detector to the photons emitted by the detector crystal itself. Therefore, the energy and simultaneity determined by β decay and γ decay rays can be used to identify background radiation events, that is, background coincidence events.

[0058] It should be noted that, as those skilled in the art can understand, the present invention does not limit the type of detector crystals of the PET imaging device. For example, the detector of the PET imaging device can use any crystal including but not limited to sodium iodide (NaI), bismuth germanate (BGO), lutetium silicate (LSO) and lutetium yttrium silicate (LYSO) as a scintillation crystal. Of course, other related technologies known to those skilled in the art other than sodium iodide (NaI), bismuth germanate (BGO), lutetium silicate (LSO) and lutetium yttrium silicate (LYSO) can also be used, which are not listed here one by one.

[0059] Preferably, in some exemplary implementations, the above-mentioned obtaining the background coincidence event data according to the background radiation data specifically includes:

[0060] The background coincidence event data is obtained based on the arrival energy and arrival time of the beta rays and gamma rays in the background radiation data.

[0061] It can be seen that the medical image registration parameter acquisition method provided in this embodiment obtains the background compliance event data based on the arrival energy and arrival time of β rays and γ rays in the local radiation data, thereby laying a foundation for obtaining the registration parameters based on the identified background compliance event data as the transmission source.

[0062] For example, see Figure 3 , Figure 3 The figure is a schematic diagram of the identification process of background coincidence events in a PET imaging device. At a certain moment, a detector (such as detector A) receives a single event A, and another detector (such as detector B) receives a single event B. The energy and arrival time of single event A are EA and TA respectively, and the energy and arrival time of single event B are EB and TB respectively, and TA>TB (event B occurs before event A). The larger of energy EA and energy EB is selected by a comparator as the larger value Emax, and the smaller of energy EA and energy EB is selected as the smaller value Emin. If the larger value Emax (such as energy EA) falls within the energy window (coincidence window) C; the smaller value Emin (such as energy EB) falls within the energy window D, and the arrival time TA-TB falls within the time window E, then the event is recorded as a background coincidence event.

[0063] Exemplarily, the value of the energy window E may be:

[0064] [max(E β ,E γ )-3σ,max(E β ,E γ )+3σ] (1)

[0065] The value of energy window D can be:

[0066] [min(E β ,E γ )-3σ,min(E β ,E γ )+3σ] (2)

[0067] The value of time window E can be:

[0068] [-ΔT max -3σ′,ΔT max +3σ′] (3)

[0069] In the above formulas (1) and (2), E β is the energy deposited by the β-ray in the crystal, E γ is the energy deposited by the γ-ray in the crystal, σ is the standard deviation of the Gaussian energy distribution of the system; in the above formula (3), △T max is the maximum possible value of the absolute value of the time difference between the β-ray and the γ-ray reaching the detector, and σ′ is the standard deviation of the Gaussian time distribution of the system.

[0070] Preferably, in some exemplary embodiments, before step S300, the medical image registration parameter acquisition method further includes:

[0071] The background coincidence event data is subjected to noise reduction processing to obtain noise-reduced background coincidence event data.

[0072] Correspondingly, step S300 obtains the registration parameters according to the CT reconstructed image and the background coincidence event data, specifically:

[0073] Acquire registration parameters according to the CT reconstructed image and the background coincidence event data after noise reduction.

[0074] Therefore, the medical image registration parameter acquisition method provided in this embodiment performs denoising on the background coincident event data, and acquires the registration parameters based on the CT reconstructed image and the denoised background coincident event data. The denoising process can not only remove redundant invalid data to improve the efficiency of data processing, but also lay a good foundation for improving the accuracy of the registration parameters between the CT reconstructed image and the PET reconstructed image.

[0075] Preferably, in some exemplary embodiments, the noise reduction processing of the background compliance event data described above includes: merging at least two original response lines (formed by connecting two crystals) into a combined response line (for example, formed by connecting two or more crystal modules), and obtaining the noise-reduced background compliance event data based on the background compliance event data received by at least one of the combined response lines.

[0076] Therefore, the medical image registration parameter acquisition method provided in this embodiment reduces the adverse effect of the low background event calculation rate caused by the weak background signal strength of a single original response line by merging at least two original response lines into a combined response line, and obtaining the noise-reduced background compliance event data based on the background compliance event data received by at least one of the combined response lines, thereby increasing the background event count received on a single response line, effectively reducing statistical noise, and further improving the accuracy of the acquired registration parameters.

[0077] In some other exemplary embodiments, the noise reduction processing of the background coincidence event data described above can also be achieved by smoothing the original background coincidence event data received by the original response line to obtain the local coincidence event data after noise reduction. For more details on how to smooth the original background coincidence event data received by the original response line, please refer to the adaptive understanding of the relevant content about noise reduction by smoothing known to those skilled in the art. Due to space limitations, detailed description will not be given here.

[0078] It should be noted that, as those skilled in the art can understand, the present invention does not limit the specific method for performing noise reduction processing on the background conforming event data. In other embodiments, other related technologies known to those skilled in the art other than the noise reduction processing methods given above may also be used, including but not limited to filtering methods and inputting the background conforming event data into a trained neural network model for noise reduction processing, etc., which are not listed one by one.

[0079] Preferably, in one embodiment, obtaining the registration parameters according to the CT reconstructed image and the background coincidence event data in step S300 specifically includes:

[0080] S310: acquiring a first attenuation image in the coordinate system of the CT imaging device according to the CT reconstructed image, and acquiring a second attenuation image in the coordinate system of the PET imaging device according to the background coincidence event data;

[0081] S320: Iteratively updating the second attenuation image using a maximum likelihood function estimation method according to the background coincidence event data, the first attenuation image, and the estimated registration parameters until a preset end condition is met;

[0082] S330: Using the estimated registration parameter corresponding to the maximum likelihood function as the registration parameter.

[0083] Therefore, the medical image registration parameter acquisition method provided in this embodiment can further improve the accuracy of the registration parameters between the CT reconstructed image and the PET reconstructed image through the maximum likelihood function estimation method.

[0084] Preferably, in some exemplary embodiments, in the process of iteratively updating the second attenuation image, an optimization method is used to obtain the estimated registration parameters. Thus, the estimated values ​​of the estimated registration parameters R and T are updated by the optimization method. In some preferred embodiments, the optimization method may be the steepest descent method, Newton's method or conjugate gradient method, etc. It should be noted that, as those skilled in the art can understand, the present invention does not specifically limit the optimization method. In other embodiments, related optimization techniques known to those skilled in the art other than the steepest descent method, Newton's method and conjugate gradient method may also be used. Due to space limitations, examples are not given one by one. Further, the present invention does not limit the preset end condition. For example, in some embodiments, the preset end condition may be that the number of iterations reaches a preset value. In other embodiments, the preset end condition may be that the value of the maximum likelihood function begins to decrease.

[0085] Exemplarily, specifically, in step S310, a first attenuation image in the coordinate system of the CT imaging device is acquired according to the CT reconstructed image.

[0086] In some exemplary embodiments, the likelihood function of the background coincident event data is shown in the following equation (4):

[0087]

[0088] In the above formula (4), R and T are the registration parameters, where R is a rotation matrix with 3 rows and 3 columns, and T is a translation vector with 3 rows and 1 column. L is the likelihood function, y i is the measured background event count rate on the i-th response line, is the expected background event count rate. The following formula (5) gives:

[0089]

[0090] In the above formula (5), a i is the attenuation effect factor on the i-th response line, s i is the background scattering event count rate on the i-th response line, b i is the empty scan background count rate on the i-th response line. Among them, the attenuation effect factor a on the i-th response line i The following formula (6) gives:

[0091]

[0092] In the above formula (6), l ij is the intercept of the i-th response line in the j-th voxel, μj is the attenuation coefficient.

[0093] μ=Rμ CT +T (7)

[0094] In the above formula (7), μ is the second attenuation image in the PET imaging device coordinate system, μ CT It is the first attenuation image in the coordinate system of the CT imaging device.

[0095] By maximizing the likelihood function L, we can obtain the estimated values ​​of the rotation matrix R and the translation vector T, as shown in equation (8):

[0096]

[0097] More specifically, as described above, an optimization algorithm may be used to obtain estimated values ​​of the rotation matrix R and the translation vector T.

[0098] Finally, the estimated registration parameter corresponding to the maximum likelihood function is used as the registration parameter between the CT reconstructed image and the PET reconstructed image.

[0099] Another embodiment of the present invention provides a medical image imaging system, which includes: a PET imaging system 100, a CT imaging system 200 and a registration parameter acquisition device 300. Specifically, the PET imaging system 100 is configured to acquire a CT reconstructed image of a registration phantom placed in its field of view; wherein the registration phantom does not contain a radiation source. The CT imaging system 200 is configured to collect background coincidence event data when the registration phantom is placed in its field of view. The registration parameter acquisition device 300 is configured to acquire registration parameters based on the CT reconstructed image and the background coincidence event data.

[0100] Therefore, the medical image imaging system provided in the present embodiment utilizes the spontaneous background radiation of the PET imaging device (exemplarily, the detector of the PET imaging device is an LSO or LYSO scintillation crystal detector) as a transmission source after energy information identification to obtain the attenuation image of the registration phantom, without the need to perfuse the registration phantom or prepare a solid registration source, thereby simplifying the operation process, saving manpower and material resources, improving the registration efficiency, and laying a solid foundation for the rapid registration of PET reconstructed images and CT reconstructed images; and reducing the radiation damage of the radiation source to the operator; further, since there is no need to perfuse the registration phantom or prepare a solid registration source, the PET imaging device in the medical image imaging system provided in the present embodiment may not have an external radiation source installation device and a movement device, thereby significantly reducing the hardware cost.

[0101] In addition, in some preferred embodiments, the medical imaging system may further include a storage device (not shown in the figure), which may store data or information generated by other devices. In some embodiments, the storage device may store data and / or information collected by the CT imaging device 200 and the PET imaging device 100, such as CT scan reconstructed images, background coincidence event data, etc. In some embodiments, the storage device may store data and / or information processed by the registration parameter acquisition device 300, such as registration parameters between CT reconstructed images and PET reconstructed images. The storage device may include one or more storage components, each of which may be an independent device or part of other devices. The storage device may be local or implemented through the cloud.

[0102] In some other preferred embodiments, the medical imaging system may further include a terminal (not shown in the figure), and the operator may issue operation instructions to the imaging device 100, the CT imaging device 200, and the registration parameter acquisition device 300 through the terminal, so that the terminal performs designated operations on the PET imaging device 100, the CT imaging device 200, and the registration parameter acquisition device 300, for example, irradiating and imaging a designated body part of the scanned object (such as a patient). In some embodiments, the terminal may enable the registration parameter acquisition device 300 to perform the medical image registration parameter acquisition method as shown in some embodiments of this specification through instructions. In some embodiments, the terminal may be one of or any combination of other devices having input and / or output functions, such as a mobile device, a tablet computer, a laptop computer, a desktop computer, etc.

[0103] In some other preferred embodiments, the medical imaging system may further include a network (not shown in the figure), which may connect the components of the medical imaging system and / or connect the system with external resources. The network enables communication between the components and with other parts outside the system to facilitate the exchange of data and / or information. In some embodiments, one or more components in the medical imaging system (e.g., PET imaging device 100, CT imaging device 200, registration parameter acquisition device 300, storage device, terminal) may send data and / or information to other components via the network. In some embodiments, the network may be any one or more of a wired network or a wireless network.

[0104] Another embodiment of the present invention further provides an imaging method of a PET-CT system, wherein the PET-CT system includes a CT imaging device and a PET imaging device. Figure 5 , Figure 5 For, from Figure 5 It can be seen that the imaging method of the PET-CT system provided in this embodiment includes:

[0105] SA1: Acquire PET data of the detected object within the field of view of the PET imaging device;

[0106] SA2: Acquire CT data of the test object within the field of view of the CT imaging device;

[0107] SA3: Acquire registration parameters, wherein the registration parameters represent a mapping relationship between aligning the CT data acquired by the CT imaging device to the PET data acquired by the PET imaging device, and the registration parameters are obtained based on the CT calibration data and background coincidence event data respectively acquired by the PET-CT system using a registration phantom;

[0108] SA4: aligning the CT data to the PET data according to the registration parameters to obtain an attenuation map;

[0109] SA5: Reconstruct the PET data according to the attenuation map to obtain a target PET image.

[0110] It can be seen that the imaging method of the PET-CT system provided in this embodiment uses the spontaneous background radiation of the PET imaging device as a transmission source after energy information identification to obtain the attenuation image of the registration phantom, without the need to perfuse the registration phantom or prepare a solid registration source, thereby simplifying the operation process, not only saving manpower and material resources and significantly improving the registration efficiency; but also reducing the radiation damage to the operator caused by the radiation source; further, since there is no need to perfuse the registration phantom or prepare a solid registration source, the imaging method of the PET-CT system provided in this embodiment can be applied to PET imaging devices without external radiation source installation devices and movement devices; the hardware requirements for the PET-CT imaging device are relatively low; further, this embodiment does not need to increase any hardware cost, has good applicability and is easy to deploy and implement.

[0111] Specifically, since the imaging method of the PET-CT system provided in this embodiment has the same inventive concept as the medical image registration parameter acquisition method provided in each embodiment of the above embodiment, due to space limitations, the more detailed contents of steps SA1 to SA3 of the imaging method of the PET-CT system provided in this embodiment can be found in the relevant description of the medical image registration parameter acquisition method provided in each embodiment of the above embodiment for adaptive understanding, and will not be elaborated here. In addition, for more detailed contents on how to align CT data and PET data according to the registration parameters to obtain the attenuation map and how to reconstruct the PET data according to the attenuation map to obtain the target PET image, please refer to the relevant technologies known to those skilled in the art, and will not be elaborated here.

[0112] Another embodiment of the present invention provides an electronic device, please refer to Figure 6, which schematically shows a block diagram of an electronic device provided by an embodiment of the present invention. Figure 6 As shown, the electronic device includes a processor 410 and a memory 430, and the memory 430 stores a computer program. When the computer program is executed by the processor 410, the medical image registration parameter acquisition method described above is implemented.

[0113] like Figure 6 As shown, the electronic device also includes a communication interface 420 and a communication bus 440, wherein the processor 410, the communication interface 420, and the memory 430 communicate with each other through the communication bus 440. The communication bus 440 can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The communication bus 440 can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, only one thick line is used in the figure, but it does not mean that there is only one bus or one type of bus. The communication interface 420 is used for communication between the above-mentioned electronic device and other devices.

[0114] The processor 410 referred to in the present invention may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc. The processor 410 is the control center of the electronic device, and uses various interfaces and lines to connect various parts of the entire electronic device.

[0115] The memory 430 may be used to store the computer program, and the processor 410 implements various functions of the electronic device by running or executing the computer program stored in the memory 430 and calling the data stored in the memory 430 .

[0116] The memory 430 may include non-volatile and / or volatile memory. 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. 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).

[0117] Yet another embodiment of the present invention provides a readable storage medium, wherein the readable storage medium stores a computer program, and when the computer program is executed by a processor, the medical image registration parameter acquisition method described above can be implemented.

[0118] The readable storage medium of the embodiment of the present invention can adopt any combination of one or more computer-readable media. The readable medium can be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium can be, for example, but not limited to, a system, device or device of electricity, magnetism, light, electromagnetic, infrared or semiconductor, or any combination of the above. More specific examples (non-exhaustive list) of computer-readable storage media include: an electrical connection with one or more wires, a portable computer hard disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this article, a computer-readable storage medium can be any tangible medium containing or storing a program, which can be used by an instruction execution system, a device or a device or used in combination with it.

[0119] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, which carry computer-readable program code. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. Computer-readable signal media may also be any computer-readable medium other than a computer-readable storage medium, which may send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0120] Computer program code for performing the operation of the present invention may be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0121] In summary, compared with the prior art, the medical image registration parameter acquisition method, system, PET-CT system imaging method, electronic device and medium provided by the present invention have the following advantages:

[0122] The medical image configuration parameter acquisition method provided by the present invention utilizes the spontaneous background radiation of a PET imaging device (exemplarily, the detector of the PET imaging device is an LSO or LYSO scintillation crystal detector) as a transmission source after energy information screening to obtain an attenuation image of a registration phantom. There is no need to perfuse the registration phantom or prepare a solid registration source, thereby simplifying the operation process, saving manpower and material resources, improving the registration efficiency, and laying a solid foundation for the rapid registration of PET reconstructed images and CT reconstructed images; and it can reduce the radiation damage of the radiation source to the operator; further, since there is no need to perfuse the registration phantom or prepare a solid registration source, the hardware requirements for the PET-CT imaging device are significantly reduced, and the present invention can be applied to PET imaging devices without external radiation source installation devices and motion devices; further, the present invention does not need to increase any hardware cost, has good applicability and is easy to deploy and implement.

[0123] Since the medical image imaging system, imaging method, electronic device and storage medium of the PET-CT system provided by the present invention belong to the same inventive concept as the medical image registration parameter acquisition method provided by the present invention, the medical image imaging system, imaging method, electronic device and storage medium of the PET-CT system provided by the present invention at least have all the advantages of the medical image registration parameter acquisition method provided by the present invention. For details, please refer to the relevant description of the beneficial effects of the above-mentioned medical image registration parameter acquisition method, which will not be repeated here.

[0124] It should be noted that the devices and methods disclosed in the embodiments of this article can also be implemented in other ways. The device implementation described above is only schematic. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the devices, methods and computer program products according to multiple embodiments of this article. In this regard, each box in the flowchart or block diagram can represent a part of a module, program or code, and the module, program segment or part of the code contains one or more executable instructions for implementing the specified logical function, and the module, program segment or part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart can be implemented by a dedicated hardware-based system for performing a specified function or action, or can be implemented by a combination of dedicated hardware and computer instructions.

[0125] In addition, the functional modules in the various embodiments of this document may be integrated together to form an independent part, or each module may exist independently, or two or more modules may be integrated to form an independent part.

[0126] The above description is only a description of the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any changes and modifications made by a person skilled in the art in the field of the present invention based on the above disclosure are within the scope of protection of the present invention. Obviously, a person skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations fall within the scope of the present invention and its equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for obtaining medical image registration parameters, used in a PET-CT system, wherein the PET-CT system comprises a CT imaging device and a PET imaging device, characterized in that: The medical image registration parameter acquisition method comprises: Placing a registration phantom within the field of view of the CT imaging device to obtain a CT reconstructed image of the registration phantom; wherein the registration phantom does not contain a radiation source; Placing the registration phantom within the field of view of a PET imaging device to collect background coincidence event data; According to the CT reconstructed image and the background coincidence event data, a registration parameter is acquired, wherein the registration parameter represents a mapping relationship for aligning the CT data acquired by the CT imaging device to the PET data acquired by the PET imaging device.

2. The method for obtaining medical image registration parameters according to claim 1, characterized in that: Background radiation data from a detector crystal of the PET imaging device is collected, and the background coincidence event data is obtained according to the background radiation data.

3. The method for obtaining medical image registration parameters according to claim 2, characterized in that: The background coincidence event data is acquired according to the arrival energy and arrival time of the beta rays and gamma rays in the background radiation data.

4. The method for obtaining medical image registration parameters according to claim 1, characterized in that: The background coincidence event data is subjected to denoising to obtain the denoised background coincidence event data; and a registration parameter is obtained according to the CT reconstructed image and the denoised background coincidence event data.

5. The method for obtaining medical image registration parameters according to claim 4, characterized in that: The background coincidence event data is subjected to noise reduction processing, including: Merging at least two original response lines into a combined response line, and acquiring the background coincidence event data after noise reduction according to the background coincidence event data received by at least one of the combined response lines; Alternatively, the original background coincidence event data received by the original response line is smoothed to obtain the background coincidence event data after noise reduction.

6. The method for obtaining medical image registration parameters according to claim 1, characterized in that: Acquire a first attenuation image in the coordinate system of the CT imaging device according to the CT reconstructed image, and acquire a second attenuation image in the coordinate system of the PET imaging device according to the background coincidence event data; Iteratively updating the second attenuation image using a maximum likelihood function estimation method according to the background coincidence event data, the first attenuation image, and the estimated registration parameters until a preset end condition is met; The estimated registration parameter corresponding to the maximum likelihood function is used as the registration parameter.

7. The method for obtaining medical image registration parameters according to claim 6, characterized in that: In the process of iteratively updating the second attenuation image, an optimization method is adopted to obtain the estimated registration parameters.

8. A medical imaging system, characterized in that: include: A PET imaging system configured to acquire a CT reconstructed image of a registration phantom placed within its field of view; wherein the registration phantom does not contain a radiation source; a CT imaging system configured to acquire background coincidence event data when the registration phantom is positioned within its field of view; The registration parameter acquisition device is configured to acquire the registration parameters according to the CT reconstructed image and the background coincidence event data, wherein the registration parameters represent the mapping relationship of aligning the CT data collected by the CT imaging device to the PET data collected by the PET imaging device.

9. An imaging method of a PET-CT system, wherein the PET-CT system comprises a CT imaging device and a PET imaging device, characterized in that: include: Acquire PET data of the detected object within the field of view of the PET imaging device; Acquire CT data of the detected object within the field of view of the CT imaging device; Acquire registration parameters, wherein the registration parameters represent a mapping relationship between aligning the CT data acquired by the CT imaging device to the PET data acquired by the PET imaging device, and the registration parameters are obtained based on the CT calibration data and background coincidence event data respectively acquired by the PET-CT system using a registration phantom; aligning the CT data to the PET data according to the registration parameters to obtain an attenuation map; The PET data is reconstructed according to the attenuation map to obtain a target PET image.

10. A readable storage medium, characterized in that: The readable storage medium stores a computer program, and when the computer program is executed by a processor, the medical image registration parameter acquisition method according to any one of claims 1 to 7 or the imaging method according to claim 9 is implemented.

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