QUANTITATIVE RECONSTRUCTION FOR MYOCARDIAL PERFUSION SPECT - AN EFFICIENT APPROACH BY DEPTH-DEPENDENT DECONVOLUTION AND MATRIX ROTATION

An efficient reconstruction method for myocardial perfusion single-pho ton emission computed tomography (SPECT) has been developed which comp ensates simultaneously for attenuation, scatter, and resolution variat ion. The scattered photons in the primary-energy-window measurements a re approximately removed by subtracting the weighted scatter-energy-wi ndow samples. The resolution variation is corrected by deconvolving th e subtracted data with the detector-response kernel in frequency space using the depth-dependent frequency relation. The attenuated photons are compensated by recursively tracing the attenuation factors through the object-specific attenuation map. An experimental chest phantom wi th defects inside myocardium was used to test the method. The attenuat ion map of the phantom was reconstructed from transmission scans using a flat external source and a high-resolution parallel-hole collimator of a single-detector system. The detector-response kernel was approxi mated from measurements of a point source in air at several depths fro m the collimator surface. The emission data were acquired by the same detector setting. A computer simulation using similar protocols as in the experiment was performed. Both the simulation and experiment showe d significant improvement in quantification with the proposed method, as compared to the conventional filtered-backprojection technique. The quantitative gain by the additional deconvolution was demonstrated. T he computation time was less than 20 min on a HP/730 desktop computer for reconstruction of a 128(2) x 64 array from 128 projections of 128 x 64 samples.