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CN-121987227-A - SPECT image reconstruction method, equipment and medium applying scattered photons

CN121987227ACN 121987227 ACN121987227 ACN 121987227ACN-121987227-A

Abstract

The application relates to the technical field of nuclear medicine imaging, in particular to a SPECT image reconstruction method, equipment and medium applying scattered photons, wherein the method comprises the steps of determining an energy window group according to radionuclides, and acquiring an attenuation correction chart and a DRR image based on a CT image; the method comprises the steps of collecting data based on energy window groups, inputting DRR images and all energy window data into a projection domain scattering correction model so that the projection domain scattering correction model outputs low-noise projection data without scattered photons, then carrying out tomographic reconstruction on the low-noise projection data to generate low-noise tomographic reconstructed images, or carrying out tomographic reconstruction on all energy window data to obtain tomographic reconstructed images corresponding to all energy window data, and then inputting an attenuation correction chart and all tomographic reconstructed images into an image domain scattering correction model so that the image domain scattering correction model outputs low-noise tomographic reconstructed images.

Inventors

  • CHEN HAIXIN
  • CHEN JUNHUA
  • YANG XUESONG
  • DENG XIAO
  • HUANG GANG

Assignees

  • 瑞石心禾(河北)医疗科技有限公司

Dates

Publication Date
20260508
Application Date
20251231

Claims (10)

  1. 1. A SPECT image reconstruction method using scattered photons, wherein the SPECT image reconstruction method using scattered photons includes the steps of: S1, determining an energy window group according to the radionuclide used currently by a SPECT system, and acquiring an attenuation correction chart and a DRR image of a projection acquisition position based on a CT image, wherein the energy window group comprises at least two energy windows, and the energy ranges corresponding to all the energy windows are different; s2, data acquisition is carried out based on the energy window groups so as to obtain energy window data corresponding to each energy window; S3, generating a low-noise tomographic reconstructed image according to all the energy window data and the DRR image or all the energy window data and the attenuation correction map; The step S3 specifically comprises the following steps: D1, inputting the DRR image and all the energy window data into a pre-trained projection domain scattering correction model so that the projection domain scattering correction model outputs low-noise projection data without scattered photons, and then carrying out tomographic reconstruction on the low-noise projection data to generate a low-noise tomographic reconstructed image; Or E1, performing fault reconstruction on each energy window data to obtain fault reconstruction images corresponding to each energy window data, and then inputting the attenuation correction map and all fault reconstruction images into a pre-trained image domain scattering correction model so that the image domain scattering correction model outputs a low-noise fault reconstruction image.
  2. 2. The SPECT image reconstruction method of claim 1 wherein the pre-training process of the projection domain scatter correction model includes: f1, acquiring human body attenuation distribution and organ masks; f2, obtaining simulated SPECT according to preset human organ drug uptake distribution and the organ mask; F3, modeling a SPECT system according to the simulated SPECT and the human body attenuation distribution by utilizing Meng Ka simulation so as to obtain non-scattering projection data and simulation projection data containing scattered photons corresponding to different energy windows; f4, generating a training DRR image according to the human body attenuation distribution; And F5, training the projection domain scattering correction model by using the non-scattering projection data, the training DRR image and all the simulation projection data containing scattered photons.
  3. 3. The SPECT image reconstruction method of claim 1 wherein the pre-training process of the image domain scatter correction model includes: G1, acquiring human body attenuation distribution and organ masks; g2, acquiring simulated SPECT according to the preset human organ drug uptake distribution and the organ mask; G3, modeling a SPECT system by utilizing Meng Ka simulation according to the simulated SPECT and the human body attenuation distribution so as to obtain non-scattering projection data and simulation projection data containing scattered photons corresponding to different energy windows; G4, performing fault reconstruction on the simulated projection data containing scattered photons to obtain a simulated fault image; g5, carrying out fault reconstruction on the scattering-free projection data to obtain a scattering-free fault reconstructed image; And G6, training the image domain scattering correction model by using the human body attenuation distribution, the non-scattering tomographic reconstructed image and all the simulated tomographic images.
  4. 4. A SPECT image reconstruction method using scattered photons according to claim 2 or 3, wherein the human attenuation profile and the organ mask are obtained based on XCAT simulation model simulations or generated based on CT images of a real patient.
  5. 5. The method of SPECT image reconstruction with scattered photons of claim 1 wherein, when the radionuclide is Y90, the process of determining the set of energy windows from the radionuclide currently in use in the SPECT system includes: A1, determining a target energy window width based on Meng Ka simulation, wherein the target energy window width is the energy window width that the ratio of unscattered photons to total photons in Meng Ka simulation is larger than a preset ratio and the interaction characteristic of gamma photons and physics is smaller than a preset action characteristic; a2, integrating a plurality of continuous energy windows with the energy range being the target energy window width into an energy window group, and setting the lower limit value of the energy range of the energy window with the lower limit value of the energy range being less than 50keV to be 50keV.
  6. 6. The method of SPECT image reconstruction with scattered photons of claim 1 wherein the set of energy windows includes two energy windows, a first main energy window and a first lower scattered energy window, respectively, when the radionuclide is 99m Tc, the process of determining the set of energy windows from the radionuclide currently in use in the SPECT system includes: b1, determining a first main energy peak corresponding to 99m Tc according to emission probability of 99m Tc and photon detection efficiency and image quality of the SPECT system; B2, calculating a first main energy window width according to the energy value corresponding to the first main energy peak and a first preset energy resolution; B3, taking the first main energy peak as a center, and constructing a first main energy window according to the width of the first main energy window; and B4, taking the energy lower limit value of the first main energy window as the energy upper limit value of the first lower scattering energy window, constructing a first lower scattering energy window with the energy window width being the same as the first main energy window width, and setting the lower limit value of the energy range corresponding to the first lower scattering energy window as 50keV when the lower limit value of the energy range corresponding to the first lower scattering energy window is smaller than 50keV.
  7. 7. The SPECT image reconstruction method of claim 6 wherein the first principal energy window width is calculated as: ; Wherein, the Representing the width of the first principal energy window, The energy value of the main energy peak corresponding to 99m Tc is represented, Representing a first preset energy resolution.
  8. 8. The method of SPECT image reconstruction using scattered photons of claim 1 wherein, when the radionuclide is 225 Ac、 177 Lu or 131 I, the plurality of energy windows contained in the set of energy windows are divided into at least one second main energy window, at least one up-scatter energy window, and at least one second down-scatter energy window, each of the second main energy windows corresponding to one up-scatter energy window and one of the second down-scatter energy windows, the process of determining the set of energy windows from the radionuclide currently in use in the SPECT system comprising: C1, determining a second main energy peak corresponding to the radionuclide according to the emission probability of the radionuclide, the photon detection efficiency of the SPECT system and the image quality; c2, calculating a second main energy window width according to the energy value corresponding to the second main energy peak and a second preset energy resolution; C3, constructing a second main energy window by taking the second main energy peak as a center according to the width of the second main energy window; C4, taking the energy lower limit value of the second main energy window as the energy upper limit value of the second lower scattering energy window, constructing a second lower scattering energy window with the same energy window width as the second main energy window width, and setting the lower limit value of the energy range corresponding to the second lower scattering energy window as 50keV when the lower limit value of the energy range corresponding to the second lower scattering energy window is smaller than 50keV; And C5, taking the energy upper limit value of the second main energy window as the energy lower limit value of the upper scattering energy window, and constructing the upper scattering energy window with the energy window width being half of the width of the second main energy window.
  9. 9. An electronic device comprising a processor and a memory storing computer readable instructions that, when executed by the processor, perform the steps in the method of any of claims 1-8.
  10. 10. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, performs the steps of the method according to any of claims 1-8.

Description

SPECT image reconstruction method, equipment and medium applying scattered photons Technical Field The application relates to the technical field of nuclear medicine imaging, in particular to a SPECT image reconstruction method, equipment and medium applying scattered photons. Background Single Photon Emission Computed Tomography (SPECT) techniques, whose imaging quality is directly related to the accuracy and reliability of clinical diagnosis, serve as a core means of nuclear medicine diagnosis. In the conventional SPECT imaging process, due to the existence of compton scattering effect, a large number of photons interact with human tissues to generate energy attenuation and direction change, and the scattered photons can be mixed into a main energy window signal, so that a series of quality problems such as contrast reduction, boundary blurring, quantitative error increase and the like occur in a reconstructed image. The current mainstream scattering correction method adopts a dual-energy window subtraction technology, and the method is characterized in that two energy acquisition windows of a main energy window and a scattering energy window are set, scattered photons are assumed to show uniform characteristics on spatial distribution or to form a simple linear relation with scattering energy window counting, and then estimated scattering components are subtracted from main energy window data according to a fixed proportionality coefficient. However, the conventional method has three significant defects that firstly, the scattering distribution in actual clinical imaging has obvious non-uniform characteristics, particularly at complex tissue structures and organ boundaries, the simple linear proportion assumption can lead to insufficient scattering correction precision, secondly, the data acquired by the scattering energy window actually contains part of useful information, the direct subtraction operation can cause unnecessary loss of effective signals, and most importantly, the subtraction process can obviously amplify image noise, seriously reduce the signal-to-noise ratio of images and influence the accuracy of subsequent quantitative analysis and diagnosis. In addition, the adaptability of the prior art to different radionuclides is poor, the special energy spectrum characteristics of different radionuclides such as Y90, 99mTc, 225Ac, 177Lu and 131I cannot be optimized, the quality of reconstructed images is uneven, and the problems severely restrict the application value of the SPECT technology in accurate medical treatment and quantitative analysis. In view of the above problems, no effective technical solution is currently available. Disclosure of Invention The application aims to provide a SPECT image reconstruction method, equipment and medium applying scattered photons, which can effectively improve the application value of a SPECT technology in accurate medical treatment and quantitative analysis. In a first aspect, the present application provides a SPECT image reconstruction method using scattered photons, comprising the steps of: S1, determining an energy window group according to the radionuclide used currently by a SPECT system, and acquiring an attenuation correction chart and a DRR image of a projection acquisition position based on a CT image, wherein the energy window group comprises at least two energy windows, and the energy ranges corresponding to all the energy windows are different; s2, data acquisition is carried out based on the energy window groups so as to obtain energy window data corresponding to each energy window; S3, generating a low-noise tomographic reconstructed image according to all energy window data and the DRR image or all energy window data and the attenuation correction map; The step S3 specifically comprises the following steps: D1, inputting the DRR image and all energy window data into a pre-trained projection domain scattering correction model so that the projection domain scattering correction model outputs low-noise projection data without scattered photons, and then carrying out tomographic reconstruction on the low-noise projection data to generate a low-noise tomographic reconstructed image; or E1, performing fault reconstruction on each energy window data to obtain fault reconstructed images corresponding to each energy window data, and then inputting the attenuation correction chart and all fault reconstructed images into a pre-trained image domain scattering correction model so that the image domain scattering correction model outputs a low-noise fault reconstructed image. According to the SPECT image reconstruction method using scattered photons, the scattered photons can be estimated and removed more accurately through the customized multi-energy window group and the scattering correction model, and noise amplification caused by traditional subtraction operation is avoided, so that the contrast ratio, resolution ratio and quantitative accuracy of