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CN-121995423-A - Gamma imaging method and system with low cost and high dynamic range

CN121995423ACN 121995423 ACN121995423 ACN 121995423ACN-121995423-A

Abstract

The application belongs to the technical field of nuclear medicine imaging, and discloses a gamma imaging method and a gamma imaging system with low cost and high dynamic range, wherein the system comprises a detector array, a detector module and a detector module, wherein the detector array is formed by splicing a plurality of detector modules, and the detector module comprises a silicon photomultiplier array, a pixelated scintillator array coupled to the front side of the silicon photomultiplier array and a front end readout circuit electrically connected with the silicon photomultiplier array; the imaging system comprises a pixelated scintillator array, a silicon photomultiplier array, a front-end reading circuit, an upper computer, a segmentation polynomial calibration algorithm, an energy weight iterative reconstruction algorithm and an imaging system, wherein the pixelated scintillator array is used for receiving and responding gamma rays to generate scintillation light, the silicon photomultiplier array is used for converting the scintillation light into electric signals, the front-end reading circuit is used for preprocessing and reading the electric signals, the upper computer is used for acquiring detection position information of gamma events and calibrated real energy values based on the segmentation polynomial calibration algorithm according to the reading signals of all detector modules, and the image reconstruction is carried out by combining the energy weight iterative reconstruction algorithm, so that the imaging system has low cost and high dynamic range gamma imaging capability and can remarkably improve imaging quality.

Inventors

  • XU CHENGCONG
  • CHEN JUNHUA
  • FANG YANG
  • DENG XIAO

Assignees

  • 瑞石心禾(河北)医疗科技有限公司
  • 清芯探测(河北)科技有限公司

Dates

Publication Date
20260508
Application Date
20260302

Claims (10)

  1. 1. A low cost high dynamic range gamma imaging system comprising: the detector array (1) is formed by splicing a plurality of detector modules (2), the detector modules (2) comprise a silicon photomultiplier array (201), a pixelated scintillator array (202) coupled to the front side of the silicon photomultiplier array (201) and a front-end readout circuit (203) electrically connected with the silicon photomultiplier array (201), the pixelated scintillator array (202) is used for receiving and responding gamma rays to generate scintillation light, the silicon photomultiplier array (201) is used for converting the scintillation light into an electric signal, and the front-end readout circuit (203) is used for preprocessing and reading the electric signal; The upper computer (3) is used for acquiring the detection position information of the gamma event and the calibrated real energy value based on a piecewise polynomial calibration algorithm according to the read-out signals of the detector modules (2), and carrying out image reconstruction by combining an energy weight iterative reconstruction algorithm.
  2. 2. The low cost high dynamic range gamma imaging system of claim 1, wherein each silicon photomultiplier array (201) comprises a plurality of lateral pixel columns and a plurality of longitudinal pixel columns as one pixel unit, the pixelated scintillator array (202) comprises a plurality of lateral scintillator crystal strips (2021) and a plurality of longitudinal scintillator crystal strips (2022), a projection of each lateral scintillator crystal strip (2021) along a normal direction of the detector module (2) coincides with a projection of a lateral center line of each lateral pixel column along a normal direction of the detector module (2), and a projection of each longitudinal scintillator crystal strip (2022) along a normal direction of the detector module (2) coincides with a projection of a longitudinal center line of each longitudinal pixel column along a normal direction of the detector module (2).
  3. 3. The low cost high dynamic range gamma imaging system of claim 1, wherein the pixelated scintillator array (202) is directly coupled to the front side of the silicon photomultiplier array (201) by optical glue or light guides.
  4. 4. A low cost high dynamic range gamma imaging system according to claim 2, wherein the front end readout circuitry (203) comprises a channel compression readout network (2031), the channel compression readout network (2031) being configured to output electrical signals of all pixel cells of a same one of the silicon photomultiplier arrays (201) from four common output buses resulting in four analog signals corresponding to a lateral positive direction, a lateral negative direction, a longitudinal positive direction and a longitudinal negative direction, respectively.
  5. 5. The low cost high dynamic range gamma imaging system of claim 4, wherein said channel compression readout network (2031) is a resistive weighting network through which the output of each pixel cell in said silicon photomultiplier array (201) is connected to four of said common output buses.
  6. 6. The low cost high dynamic range gamma imaging system of claim 4, wherein said front end readout circuitry (203) further comprises a preprocessing module (2032), said preprocessing module (2032) configured to preprocess four analog signals to obtain and output said readout signals, said preprocessing including filtering amplification, bias processing, pulse waveform adjustment, and analog to digital conversion processing.
  7. 7. A low cost high dynamic range gamma imaging method, based on the low cost high dynamic range gamma imaging system of any of claims 4-6, comprising the steps of: A1. acquiring a readout signal of each detector module (2); A2. according to four paths of signals in the read-out signals, detecting position information and initial energy information of a gamma event are calculated; A3. Calibrating the initial energy information by adopting a piecewise polynomial calibration algorithm to obtain a calibrated real energy value; A4. And carrying out image reconstruction by using an energy weight iterative reconstruction algorithm according to the detection position information and the real energy value, and generating a gamma ray image.
  8. 8. A low cost high dynamic range gamma imaging method according to claim 7, the method is characterized in that the step A2 comprises the following steps: A201. Calculating detection position information of a gamma event by using a gravity center positioning algorithm according to four paths of signals in the read-out signals; A202. and calculating the sum of the energy corresponding to the four paths of signals in the read-out signals to obtain the initial energy information of the gamma event.
  9. 9. A low cost high dynamic range gamma imaging method according to claim 7, the method is characterized in that the step A3 comprises the following steps: A301. comparing the initial energy information with a preset energy threshold; A302. if the initial energy information is not greater than the preset energy threshold, calibrating the initial energy information according to a pre-calibrated linear mapping function to obtain a calibrated real energy value; A303. And if the initial energy information is larger than the preset energy threshold, calibrating the initial energy information according to a pre-calibrated high-order polynomial mapping function to obtain a calibrated real energy value, wherein the linear mapping function and the high-order polynomial mapping function are in smooth transition at the preset energy threshold.
  10. 10. A low cost high dynamic range gamma imaging method according to claim 7, the method is characterized in that the step A4 comprises the following steps: A401. For each gamma event, calculating the credibility weight of the gamma event according to the deviation between the real energy value of the gamma event and the preset photoelectric peak energy; A402. Based on array geometric parameters of pixel units of a detector module (2) and detection position information of each gamma event, establishing a system response matrix, and initializing an image matrix to be reconstructed, wherein each element of the system response matrix is the response probability of each image pixel to the detection position of each gamma event, and each element of the image matrix to be reconstructed is each image pixel value of an image to be reconstructed; A403. according to the credibility weight and the system response matrix, carrying out iterative reconstruction on the image matrix to be reconstructed based on an OSEM algorithm so as to update image pixel values in the image matrix to be reconstructed; A404. And (3) repeating the step A403 until a preset iteration termination condition is met, and converting the finally obtained image matrix to be reconstructed into a gamma ray image.

Description

Gamma imaging method and system with low cost and high dynamic range Technical Field The application relates to the technical field of nuclear medicine imaging, in particular to a gamma imaging method and system with low cost and high dynamic range. Background In the field of nuclear medicine imaging, gamma imaging techniques are widely used for disease diagnosis and therapy monitoring. The medical gamma imaging detector on the market at present mainly adopts two technical routes, namely a traditional scintillation crystal and photomultiplier tube (PMT) combined scheme and a novel compound semiconductor detector scheme. The traditional scheme has wider energy linear response characteristic, but the energy response range is limited by the dynamic range of the subsequent electronic hardware system, so that the gamma ray imaging capability of the system in a middle-high energy section, particularly in a high energy section, is limited. When the energy of the gamma rays exceeds the upper limit of the energy response of the detector, the system cannot accurately acquire the energy information of the high-energy gamma rays, and the imaging quality is seriously affected. The novel compound semiconductor detector (such as a CZT detector, a CdTe detector and the like) has better energy resolution, but due to the characteristic limitation of the material, the energy response range is narrower than that of the traditional scheme, the manufacturing cost is high, and the novel compound semiconductor detector is unfavorable for large-scale clinical application. In addition, in the prior art, the splicing mode of the detector module, the signal reading mechanism and the image reconstruction algorithm have an optimization space, and these factors limit the performance and the cost control of the gamma imaging system in a wide energy range together. In view of the above, there is a need in the art for improvements. Disclosure of Invention The application aims to provide a gamma imaging method and a gamma imaging system with low cost and high dynamic range, which have the gamma imaging capability with low cost and high dynamic range, can accurately acquire the energy information of high-energy gamma rays and remarkably improve the imaging quality. In a first aspect, the present application provides a low cost high dynamic range gamma imaging system comprising: The detector array is formed by splicing a plurality of detector modules, and the detector modules comprise a silicon photomultiplier array, a pixelated scintillator array coupled to the front side of the silicon photomultiplier array and a front-end readout circuit electrically connected with the silicon photomultiplier array, wherein the pixelated scintillator array is used for receiving and responding gamma rays to generate scintillation light, the silicon photomultiplier array is used for converting the scintillation light into an electric signal, and the front-end readout circuit is used for preprocessing and reading the electric signal; And the upper computer is used for acquiring the detection position information of the gamma event and the calibrated real energy value based on a piecewise polynomial calibration algorithm according to the read-out signals of the detector modules, and carrying out image reconstruction by combining an energy weight iterative reconstruction algorithm. In a second aspect, the present application provides a low-cost high-dynamic-range gamma imaging method, based on the low-cost high-dynamic-range gamma imaging system described above, comprising the steps of: A1. acquiring a read-out signal of each detector module; A2. according to four paths of signals in the read-out signals, detecting position information and initial energy information of a gamma event are calculated; A3. Calibrating the initial energy information by adopting a piecewise polynomial calibration algorithm to obtain a calibrated real energy value; A4. And carrying out image reconstruction by using an energy weight iterative reconstruction algorithm according to the detection position information and the real energy value, and generating a gamma ray image. The gamma imaging method and system with low cost and high dynamic range have the advantages that the silicon photomultiplier is used as a photoelectric conversion device, inherent cost advantages of the method and system are combined with the modularized splicing design of the detector array, the manufacturing cost of whole hardware is remarkably reduced, the upper computer can accurately compensate nonlinear response of the detector in a high-energy section by applying a piecewise polynomial calibration algorithm on a data processing layer, so that the energy response range is expanded to a wider range, accurate acquisition of high-energy gamma ray energy information is realized, in addition, noise brought by scattering events can be effectively distinguished and restrained in the image reconstruction process by co