A multi-modal single photon emission tomography method and a system using the same

Abstract

The present application discloses a multimodal single-photon emission tomography method, comprising: a multimodal integrated detection module detects an incident photon; the incident photon generates a single photoelectric effect or a Compton effect, calculates a first response position and a first energy deposition or a second response position that generates a response each time and a second energy deposition that generates a response each time, and logically determines whether the sum of the first energy deposition or the second energy deposition is within a preset low-energy or high-energy energy range of the incident photon; if so, stores the first response position and the first energy deposition that generate a signal in a single-photon emission tomography data set, stores multiple second response positions and multiple second energy depositions in a data set for Compton imaging, reconstructs the two data sets into three-dimensional images, and obtains a single-photon emission tomography three-dimensional image and a Compton imaging three-dimensional image; and fuses the two three-dimensional images in the same coordinate system to obtain a multimodal single-photon emission tomography result.

Description

Technical Field

[0001] The present application relates to a medical imaging method, and in particular, to a multi-modal single photon emission tomography method and system. Background Art

[0002] Nuclear medicine imaging equipment can perform non-invasive imaging of diseased tissues or organs in patients from outside the body. By displaying the biological activity of diseased tissues at the molecular level, it can provide the precise location, morphology, size and metabolic status of diseased tissues. Common nuclear medicine imaging equipment in reality mainly includes single photon emission tomography (SPECT) equipment and positron emission tomography (PET) equipment.

[0003] Among them, PET technology can only detect nuclides that emit positrons. By performing coincidence measurements on a pair of 511keV photons from annihilation reactions, PET will be able to image the distribution of positron-emitting nuclides. Traditional SPECT can detect nuclides that emit instantaneous photons during the decay process, but due to the detection method of the photoelectric effect, it can usually only detect photons with energies less than 300keV. Therefore, the currently commonly used nuclear medicine imaging equipment is very limited in the detectable energy range and cannot image multiple nuclides at the same time. Furthermore, current imaging technology has greatly restricted the development of new radioactive drugs. Due to the limited detectable energy range, the radioactive drugs currently in use and under development have only a small choice.

[0004] Compton camera is a new type of single photon emission imaging device with the advantages of extremely high detection efficiency, large field of view and high resolution, and has the potential for nuclear medicine imaging. Compton camera can detect photons of multiple energies at the same time. Makoto et al. of Gunma University in Japan reported the Compton camera on the patient's body. 99m Tc and 18 F Application of simultaneous imaging of two radionuclides. The ability to simultaneously detect multiple radionuclide preparations with different binding abilities on different organs makes the Compton camera feasible for improving the efficiency of nuclear medicine imaging. However, the Compton camera is only suitable for detecting photons in a higher energy range.

[0005] By integrating different imaging technologies, multimodal fusion imaging can display complex (multi-functional) biochemical processes in the body non-invasively, in vivo, in real time, precisely, and specifically, providing more comprehensive and accurate information. It has broad application prospects in early diagnosis of cancer, personalized detection, monitoring of specific cell populations and functional molecules, targeted drug tracking, prognosis judgment, and efficacy evaluation.

[0006] Multimodal fusion imaging technology plays an important role in the integration of radionuclide diagnosis and treatment. The integration of radionuclide diagnosis and treatment can combine imaging diagnosis with internal irradiation therapy using different radionuclides, which will be able to achieve the purpose of visual diagnosis and precise treatment. The integration of radionuclide diagnosis and treatment has played an important role in tumor diseases such as differentiated thyroid cancer, pheochromocytoma, bone metastasis, neuroendocrine tumors, and prostate cancer. In the context of the development of the integration of radionuclide diagnosis and treatment, imaging methods and detection equipment suitable for multi-nuclide imaging will be necessary.

[0007] However, there is currently no multi-modal integrated single photon emission imaging system and method that can perform multi-nuclide imaging. Summary of the invention

[0008] In view of the shortcomings of the prior art, the present invention provides a multi-modal single-photon emission tomography method, comprising: a multi-modal integrated detection module detects an incident photon; if the incident photon generates a single photoelectric effect on the multi-modal integrated detection module, a first response position and a first energy deposition on the multi-modal integrated detection module are calculated, and a logical judgment is made as to whether the first energy deposition is within a preset low-energy energy range of the incident photon: if they are within the preset low-energy energy range, the first response position and the first energy deposition that generate a signal are stored in a single-photon emission tomography data set, and a three-dimensional image is reconstructed for the single-photon emission tomography data set to obtain a single-photon emission tomography three-dimensional image; if a single photoelectric effect occurs on the multi-modal integrated detection module, a first response position and a first energy deposition on the multi-modal integrated detection module are calculated, and a logical judgment is made as to whether the first energy deposition is within a preset low-energy energy range of the incident photon: if they are within the preset low-energy energy range, the first response position and the first energy deposition that generate a signal are stored in a single-photon emission tomography data set, and a three-dimensional image is reconstructed for the single-photon emission tomography data set to obtain a single-photon emission tomography three-dimensional image; If a photoelectric effect occurs after a single or multiple Compton effects, the second response position of each response on the multimodal integrated detection module and the second energy deposition of each response are calculated, and a logical judgment is made as to whether the sum of the second energy deposition of each response is within the preset high-energy energy range of the incident photons: if within the preset high-energy energy range, the plurality of second response positions and the plurality of second energy depositions are stored in a data set for Compton imaging, and a three-dimensional image reconstruction is performed on the Compton imaging data set to obtain a Compton imaging three-dimensional image; the single-photon emission tomography three-dimensional image and the Compton imaging three-dimensional image are fused in the same coordinate system to obtain a multimodal single-photon emission tomography result including the distribution of low-energy and high-energy incident photons.

[0009] Furthermore, the multimodal integrated detection module includes: a mechanical collimator, the mechanical collimator includes a collimation hole, the incident photons in the preset low-energy range are collimated by the mechanical collimator and then pass through the collimation hole, and the incident photons in the preset high-energy range pass through the collimation hole of the mechanical collimator; a Compton detector, which detects the incident photons passing through the mechanical collimator and reacts to the first response position, first energy deposition, second response position, and second energy deposition where the incident photons react.

[0010] Furthermore, the mechanical collimator is located at the front end of the Compton detector and is closely fitted to the Compton detector. The mechanical collimator includes a collimation hole. The Compton detector is a position sensitive detector.

[0011] Furthermore, the mechanical collimator is a parallel hole type, fan beam type or pinhole type mechanical collimator.

[0012] Furthermore, the above detector is a single-layer Compton detector.

[0013] Furthermore, the Compton detector includes a detection crystal, and the detection crystal is a cadmium zinc telluride, cadmium telluride or gadolinium aluminum gallium garnet detection crystal.

[0014] Furthermore, the mechanical collimator can be moved on the plane of the Compton detector to adjust the projection position of the corresponding pixel of the collimating hole on the Compton detector.

[0015] Furthermore, the method for reconstructing a three-dimensional image of the above-mentioned single photon emission tomography data set includes a direct back projection method, a filtered back projection method or an iterative reconstruction method; the method for reconstructing a three-dimensional image of the above-mentioned Compton imaging data set includes a direct back projection method, a filtered back projection method, an algebraic analytical method, a maximum likelihood expectation maximization iteration, a random source set iteration method and a Bayesian reconstruction method.

[0016] The present application also relates to a multimodal single photon emission tomography system using any of the above methods, including: a radioactive drug, which is concentrated at the lesion site and radiates incident photons; a multimodal integrated detection module, including a mechanical collimator and a Compton detector, wherein the incident photons pass through the mechanical collimator and are detected by the Compton detector, and the Compton detector records and sends a first response position and a first energy deposition of the incident photons that undergo a single photoelectric effect, or records and sends multiple second response positions and second energy depositions of the incident photons that undergo a photoelectric effect after a single or multiple Compton effects; and a storage processor. , receiving and collecting a first response position and a first energy deposition as a single photon emission tomography data set, receiving and collecting a plurality of second response positions and second energy depositions where responses occur as a Compton imaging data set, performing three-dimensional image reconstruction on the single photon emission tomography data set to obtain a single photon emission tomography three-dimensional image, performing three-dimensional image reconstruction on the Compton imaging data set to obtain a Compton imaging three-dimensional image, and fusing the single photon emission tomography three-dimensional image and the Compton imaging three-dimensional image in the same coordinate system to obtain a multimodal single photon emission tomography result including the distribution of low-energy and high-energy radiation sources.

[0017] Furthermore, the multi-modal single photon emission tomography system includes a plurality of multi-modal integrated detection modules, and the multi-modal integrated detection modules are closely arranged in a ring.

[0018] The present invention proposes a multi-modal integrated single photon emission tomography method and system based on a single-layer position-sensitive Compton camera. The entire imaging system constructed based on this method will have both the detection performance of traditional SPECT for low-energy photons and the detection performance of Compton cameras for high-energy photons. The imaging system has efficient detection performance for photons from more than ten keV to MeV, covering almost all energy ranges of radioactive drugs. At the same time, the imaging system has the characteristics of simultaneous multi-nuclide and multi-energy detection, which can greatly improve the imaging efficiency in multi-nuclide diagnosis and treatment during radiotherapy. The extremely wide detectable energy range also allows more and more efficient radionuclide preparations to be used in clinical applications of radiotherapy in the future.

[0019] The advantages of the multimodal integrated single photon emission tomography method for multi-nuclide imaging are summarized as follows: (1) It supports wide energy range detection, covering almost all energy ranges of radionuclides; (2) It supports simultaneous detection of multiple nuclides and multiple energies; (3) It supports the development of more efficient new radiopharmaceuticals.

[0020] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the multimodal single photon emission tomography method of the present application.

[0022] Figure 2 This is a schematic diagram of the multi-modal integrated detection module of the present application.

[0023] Figure 3 This is a schematic diagram of the multi-modal integrated detection module of the present application that undergoes a single photoelectric effect and a single or multiple Compton effects followed by a photoelectric effect.

[0024] Figure 4 A schematic diagram of a multi-modal single photon emission tomography system of the present application is shown. DETAILED DESCRIPTION

[0025] The following is a more detailed description of the specific embodiments of the present invention in conjunction with the accompanying drawings and examples, so that the scheme of the present invention and its advantages in various aspects can be better understood. However, the specific embodiments and examples described below are only for the purpose of illustration, rather than for limiting the present invention.

[0026] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0027] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0029] Figure 1 Schematic diagram of the multimodal single photon emission tomography method of the present application.

[0030] like Figure 1 As shown, the multimodal single photon emission tomography method in this application mainly includes the following steps:

[0031] Step S1, incident photons are emitted by radioactive drugs gathered at the lesion site, and the multi-modal integrated detection module detects the incident photons.

[0032] Furthermore, the incident photon generates a photoelectric effect on the multimodal integrated detection module, wherein if a single photoelectric effect occurs, the first response position and the first energy deposition on the multimodal integrated detection module are calculated, and a logical judgment is made as to whether the first energy deposition is within the preset low-energy range of the incident photon: if within the preset low-energy range, the first response position and the first energy deposition that generate the signal are stored in the single-photon emission tomography data set, and the next photon action event is continued to be waited for. When enough first response position and first energy deposition data are recorded, the single-photon emission tomography data set is reconstructed into a three-dimensional image to obtain a single-photon emission tomography three-dimensional image; if it does not meet the preset low-energy range, the photoelectric effect data is not recorded.

[0033] If a single or multiple Compton effects occur on the multimodal integrated detection module and then a photoelectric effect occurs, the second response position of each response on the multimodal integrated detection module and the second energy deposition of each response are calculated, and a logical judgment is made as to whether the sum of the second energy deposition of each response is within the preset high-energy energy range of the incident photon: if within the preset high-energy energy range, the multiple second response positions and the multiple second energy depositions are stored in a data set for Compton imaging, and when the next photon action is waited for, and when enough multiple second response positions and second energy deposition data are recorded, a three-dimensional image reconstruction is performed on the Compton imaging data set to obtain a Compton imaging three-dimensional image;

[0034] The single photon emission tomography 3D image and the Compton imaging 3D image are fused in the same coordinate system to obtain a multimodal single photon emission tomography result including the distribution of low-energy and high-energy incident photons.

[0035] The method for fusing single photon emission tomography 3D images and Compton imaging 3D images is as follows: placing the 3D reconstruction results of the two modalities in the same coordinate system and superimposing the Compton imaging 3D image on the single photon emission tomography 3D image, wherein the single photon emission tomography 3D reconstruction results show the distribution of low-energy radiation sources, and the Compton scattering imaging 3D reconstruction results show the distribution of high-energy radiation sources. Since the two modalities are imaged by an integrated imaging device, there is no spatial position deviation, so they can be directly fused. The fusion method is to directly superimpose the 3D reconstruction results of the two modalities, and the result can simultaneously show the distribution of high-energy radiation sources and low-energy radiation sources.

[0036] Figure 2 This is a schematic diagram of the multi-modal integrated detection module of the present application. Figure 3 This is a schematic diagram of the multi-modal integrated detection module of the present application that undergoes a single photoelectric effect and a single or multiple Compton effects followed by a photoelectric effect.

[0037] like Figure 2 and Figure 3 As shown, the multi-modal integrated detection module includes a mechanical collimator and a Compton detector. The mechanical collimator collimates incident photons in a preset low-energy energy range. High-energy incident photons pass directly through the mechanical collimator. The mechanical collimator includes a collimation hole, and the incident photons pass through the collimation hole. The Compton detector detects the incident photons passing through the mechanical collimator, and reacts to the first response position, the first energy deposition, the second response position, and the second energy deposition where the incident photons react.

[0038] like Figure 2 As shown, the mechanical collimator and the Compton detector fit closely together, and the mechanical collimator is located at the front end of the Compton detector to facilitate the incident photons to enter the Compton detector after passing through the mechanical collimator. The Compton detector is a position-sensitive detector.

[0039] Furthermore, the mechanical collimator is a parallel hole type, fan beam type or pinhole type mechanical collimator. The material can be lead, tungsten, etc. The Compton detector is a detector with three-dimensional position readout and energy spectrum readout characteristics. This application uses a single-layer Compton detector. This is because Compton cameras are generally divided into multi-layer (including double-layer) Compton cameras and single-layer position-sensitive Compton cameras. Among them, the single-layer position-sensitive Compton camera has a compact structure and has a higher detection efficiency than the multi-layer Compton camera, which is the future development direction of the Compton camera.

[0040] The main detection function of the Compton detector is performed by the detection crystal. The detection crystal in the present application can be selected from one or more of cadmium zinc telluride (CZT), cadmium telluride (CdTe) or gadolinium aluminum gallium garnet (GAGG) detection crystals.

[0041] Furthermore, the mechanical collimator can be moved on the plane of the Compton detector to adjust the projection position of the corresponding pixel of the collimating hole on the Compton detector. When the mechanical collimator does not move, the collimating hole is directly opposite to the center of the detection crystal pixel. When the collimator is translated, the projection position of the collimating hole on the pixel of the corresponding detection crystal changes. The purpose of the collimator translation is to enable single photon emission tomography to achieve super-pixel reconstruction.

[0042] The present application also relates to a method for three-dimensional image reconstruction. The method for three-dimensional image reconstruction of a single photon emission tomography data set includes: direct back projection method, filtered back projection method or iterative reconstruction method; the method for three-dimensional image reconstruction of a Compton imaging data set includes: direct back projection method, filtered back projection method, algebraic analytical method, maximum likelihood expectation maximization (MLEM) iteration, random source set (SOE) iteration and Bayesian reconstruction method. When reconstructing an image, one or more of the above mentioned methods can be selected according to the actual situation.

[0043] Furthermore, the three-dimensional reconstruction method of the single photon emission tomography data set and the three-dimensional image reconstruction method of the Compton imaging data set can be used for hardware-supported three-dimensional accelerated reconstruction using acceleration cards such as a graphics processing unit (GPU) and a field programmable gate array (FPGA).

[0044] Figure 4 A schematic diagram of a multi-modal single photon emission tomography system of the present application is shown.

[0045] like Figure 4 The present application also relates to a multimodal single photon emission tomography system using the above method, the system comprising: a multimodal integrated detection module and a data storage processor, and also comprising a radioactive drug that is injected in advance and accumulated at the lesion site, and the drug can radiate incident photons.

[0046] A multimodal integrated detection module, a single multimodal integrated detection module includes a mechanical collimator and a Compton detector, the incident photons emitted from the radioactive drug are detected by the Compton detector, the Compton detector records and sends the first response position and the first energy deposition of the incident photons that undergo a single photoelectric effect, or records and sends multiple second response positions and second energy depositions of the incident photons that undergo a single or multiple Compton effects and then a photoelectric effect.

[0047] A storage processor receives and collects a first response position and a first energy deposition as a single photon emission tomography data set, receives and collects a plurality of second response positions and second energy depositions where responses occur as a Compton imaging data set, performs three-dimensional image reconstruction on the single photon emission tomography data set to obtain a single photon emission tomography three-dimensional image, performs three-dimensional image reconstruction on the Compton imaging data set to obtain a Compton imaging three-dimensional image, and fuses the single photon emission tomography three-dimensional image and the Compton imaging three-dimensional image in the same coordinate system to obtain a multimodal single photon emission tomography result including the distribution of low-energy and high-energy radiation sources.

[0048] Furthermore, the multi-modal single photon emission tomography system of the present application may include a plurality of multi-modal integrated detection modules, and the multi-modal integrated detection modules are closely arranged in a ring. The center of the ring is the space where the patient is located. Figure 4 Of course, the multi-modal integrated detection modules can also be arranged into other shapes according to actual needs, and the number of multi-modal integrated detection modules can also be adjusted according to needs, as long as the mechanical collimator and the Compton detector are closely fitted, the mechanical collimator collimates the low-energy incident photons and enters the Compton detector, and the high-energy incident photons pass through the mechanical collimator and directly enter the Compton detector.

[0049] Obviously, the above embodiments are merely examples for clearly explaining the present invention, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A multimodal single photon emission tomography method, characterized in that: include: The multi-modal integrated detection module detects the incident photons; Wherein, if the incident photon generates a single photoelectric effect on the multimodal integrated detection module, a first response position and a first energy deposition on the multimodal integrated detection module are calculated, and a logical judgment is made as to whether the first energy deposition is within a preset low-energy range of the incident photon: if within the preset low-energy range, the first response position and the first energy deposition that generate the signal are stored in a single-photon emission tomography data set, and a three-dimensional image reconstruction is performed on the single-photon emission tomography data set to obtain a single-photon emission tomography three-dimensional image; If a single or multiple Compton effects occur on the multimodal integrated detection module and then a photoelectric effect occurs, then a second response position of each response on the multimodal integrated detection module and a second energy deposition of each response are calculated, and a logical judgment is made as to whether the sum of the second energy deposition of each response is within a preset high-energy energy range of the incident photons: if within the preset high-energy energy range, then a plurality of the second response positions and a plurality of the second energy depositions are stored in a data set for Compton imaging, and a three-dimensional image reconstruction is performed on the Compton imaging data set to obtain a Compton imaging three-dimensional image; The single photon emission tomography three-dimensional image and the Compton imaging three-dimensional image are fused in the same coordinate system to obtain a multimodal single photon emission tomography result including the distribution of low-energy and high-energy incident photons; The multi-modal integrated detection module includes a mechanical collimator and a Compton detector, wherein the mechanical collimator includes a collimation hole, the incident photons in the preset low-energy range are collimated by the mechanical collimator and then pass through the collimation hole, and the incident photons in the preset high-energy range pass through the collimation hole of the mechanical collimator; the Compton detector detects the incident photons passing through the mechanical collimator, and reacts to the first response position, the first energy deposition, the second response position, and the second energy deposition where the incident photons react; The mechanical collimator is located at the front end of the Compton detector and is closely fitted with the Compton detector. The Compton detector is a position-sensitive detector.

2. A multi-modal single photon emission tomography method according to claim 1, characterized in that: The mechanical collimator is a parallel hole type, a fan beam type or a pinhole type mechanical collimator.

3. A multi-modal single photon emission tomography method as claimed in claim 1, characterized in that: The detector is a single-layer Compton detector.

4. A multi-modal single photon emission tomography method as claimed in claim 1, characterized in that: The Compton detector includes a detection crystal, and the detection crystal is a cadmium zinc telluride, cadmium telluride or gadolinium aluminum gallium garnet detection crystal.

5. A multi-modal single photon emission tomography method as claimed in claim 2, characterized in that: The mechanical collimator is movable on the plane of the Compton detector to adjust the projection position of the corresponding pixel of the collimation hole on the Compton detector.

6. A multi-modal single photon emission tomography method as claimed in claim 1, characterized in that: The method of performing three-dimensional image reconstruction on the single photon emission tomography data set includes a direct back-projection method, a filtered back-projection method or an iterative reconstruction method; Methods for reconstructing three-dimensional images of the Compton imaging data set include direct back-projection method, filtered back-projection method, algebraic analytical method, maximum likelihood expectation maximization iteration, random source set iteration method and Bayesian reconstruction method.

7. A multi-modal single photon emission tomography system using any of the methods of claims 1-6, characterized in that: include: Radiopharmaceuticals, which collect at the site of the lesion and radiate incident photons; A multi-modal integrated detection module, comprising a mechanical collimator and a Compton detector, wherein the incident photons are detected by the Compton detector after passing through the mechanical collimator, and the Compton detector records and sends a first response position and a first energy deposition of the incident photons that undergo a single photoelectric effect, or records and sends a plurality of second response positions and second energy depositions of the incident photons that undergo a photoelectric effect after a single or multiple Compton effects; A storage processor receives and collects a first response position and a first energy deposition as a single photon emission tomography data set, receives and collects a plurality of second response positions and second energy depositions where responses occur as a Compton imaging data set, performs three-dimensional image reconstruction on the single photon emission tomography data set to obtain a single photon emission tomography three-dimensional image, performs three-dimensional image reconstruction on the Compton imaging data set to obtain a Compton imaging three-dimensional image, and fuses the single photon emission tomography three-dimensional image and the Compton imaging three-dimensional image in the same coordinate system to obtain a multimodal single photon emission tomography result including the distribution of low-energy and high-energy radiation sources.

8. The multi-modal single photon emission tomography system according to claim 7, characterized in that: The multi-modal single photon emission tomography system comprises a plurality of multi-modal integrated detection modules, and the multi-modal integrated detection modules are closely arranged in a ring.

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