Nuclear Science and Techniques

《核技术》(英文版) ISSN 1001-8042 CN 31-1559/TL     2019 Impact factor 1.556

Nuclear Science and Techniques ›› 2013, Vol. 24 ›› Issue (3): 030202 doi: 10.13538/j.1001-8042/nst.2013.03.011

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PET image reconstruction with rotationally symmetric polygonal pixel grid based highly compressible system matrix

YU Yunhan1  XIA Yan1  CHEN Jing2  HONG Baoyu2  LIU Yaqiang1  WANG Shi1  MA Tianyu1   

  1. 1Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education Department of Engineering Physics, Tsinghua University, Beijing 10084, China
    2National Institute of Metrology, Beijing 100013, China
  • Received:2013-03-19
  • Contact: MA Tianyu E-mail: maty@tsinghua.edu.cn
  • Supported by:

    Supported by Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry and National Natural Science Foundation of China (No.10975086)

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YU Yunhan, XIA Yan, CHEN Jing, HONG Baoyu, LIU Yaqiang, WANG Shi, MA Tianyu. PET image reconstruction with rotationally symmetric polygonal pixel grid based highly compressible system matrix.Nuclear Science and Techniques, 2013, 24(3): 030202     doi: 10.13538/j.1001-8042/nst.2013.03.011

Abstract:

To achieve a maximum compression of system matrix in positron emission tomography (PET) image reconstruction, we proposed a polygonal image pixel division strategy in accordance with rotationally symmetric PET geometry. Geometrical definition and indexing rule for polygonal pixels were established. Image conversion from polygonal pixel structure to conventional rectangular pixel structure was implemented using a conversion matrix. A set of test images were analytically defined in polygonal pixel structure, converted to conventional rectangular pixel based images, and correctly displayed which verified the correctness of the image definition, conversion description and conversion of polygonal pixel structure. A compressed system matrix for PET image recon was generated by tap model and tested by forward-projecting three different distributions of radioactive sources to the sinogram domain and comparing them with theoretical predictions. On a practical small animal PET scanner, a compress ratio of 12.6:1 of the system matrix size was achieved with the polygonal pixel structure, comparing with the conventional rectangular pixel based tap-mode one. OS-EM iterative image reconstruction algorithms with the polygonal and conventional Cartesian pixel grid were developed. A hot rod phantom was detected and reconstructed based on these two grids with reasonable time cost. Image resolution of reconstructed images was both 1.35 mm. We conclude that it is feasible to reconstruct and display images in a polygonal image pixel structure based on a compressed system matrix in PET image reconstruction.

 

 

Key words: Positron emission tomography (PET), Rotationally symmetric polygonal pixel grid, Compressed system matrix, Image reconstruction