Performance evaluation of PET/CT based on silicon photomultiplier and photomultiplier tube under clinical imaging conditions
Objective To investigate the spatial resolution and image quality of positron emission tomography and X-ray computed tomography(PET/CT)based on the next-generation silicon photomultiplier(SiPM)and the conventional photomultiplier tube(PMT)and to explore the effects of different PET photoelectric transducers(PMT and SiPM)and the Q.Clear algorithm on the spatial resolution,quantitative accuracy,and image quality of PET/CT.Methods GE Discovery Elite PET/CT(PMT PET/CT)and GE Discovery Meaningful Insights(MI)PET/CT(SiPM PET/CT)were employed to scan the elliptical resolution phantom and NEMA NU2-2018 image quality phantom.Using the OSEM+PSF+TOF(VPFX-S)algorithm,image reconstruction was performed based on raw data of both phantoms.For the MI-acquired phantom data,additional reconstructions were conducted using the Q.Clear algorithm,with β values ranging from 150 to 550 and an increment of 100.For the elliptical resolution phantom,the radial,tangential,and axial full-width at half-maximum(FWHM)values of five line sources in three slices were calculated and averaged.For the image quality phantom,the recovery coefficient(RC),contrast recovery coefficient(CRC),contrast-to-noise ratio(CNR),percentage of background variability(PBV),background coefficient of variability(BCV)of the spheres,as well as the residual error(RE)of lung inserts at different image slices,were calculated.Results Compared to Elite,MI(VPFX-S)showed decreases in the radial,tangential,and axial FWHM of 4.25％-13.58％,7.00％-13.22％,and 6.02％-36.14％,respectively;no significant difference in RCmax for the spheres;increases in spheres'CRC and CNR of 10.17％-38.89％and 38.31％-94.95％,respectively,and decreases in spheres'PBV and BCV of 26.20％-33.82％and 31.29％-35.97％,respectively.When compared to MI(VPFX-S),MI(Q.Clear)showed decreases in the radial,tangential,and axial FWHM of 6.49％-45.02％,7.80％-35.60％,and 13.31％-36.80％,respectively;an increase in spheres'CNR of 38.31％-94.95％;decreases in spheres'PBV and BCV of 26.20％-33.82％and 6.64％-10.31％,respectively,and no significant difference in spheres'RC.With an increase in the β value,the CNR,RE,and FWHM in radial,tangential,and axial directions derived from MI(Q.Clear)increased,while RC,CRC,PBV,and BCV decreased.Conclusions Under image reconstruction using VPFX-S,the next-generation SiPM PET/CT exhibits elevated spatial resolution,hot lesion contrast,detectability,and background noise compared to the PMT PET/CT.Compared to OSEM,the Q.Clear algorithm improves spatial resolution,quantitative accuracy,and image quality,with such improvement related to the β value.The β value affects the outcomes of the Q.Clear algorithm,especially the maximum quantitative value of small lesions.This is particularly important for improving clinical diagnostic capabilities.
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