A novel geometry for SPECT imaging associated with the EM-type blind deconvolution method

Image quality of single-photon emission computerized tomography (SPECT) is essentially determined by count sensitivity of the detector and geometry of the collimator. The authors introduce a novel geometry for a dual-head SPECT system, one head equipped with a coded aperture collimator and the other head equipped with a conventional parallel hole collimator, to improve the count sensitivity. Two expectation-maximization blind deconvolution (EMBD) algorithms were derived to improve the image resolution of SPECT projections. The algorithms were evaluated using elliptical cylindrical rod phantom data and hand data. The coded aperture and parallel hole projections were acquired simultaneously using the dual-head imaging system. The acquired coded aperture projections were decoded using the standard uniformly redundant array (URA) technique to yield decoded projections. The projections acquired from the parallel hole collimator head were incorporated into the decoded images in the EMBD restoration process. Using the coded aperture collimator, the count sensitivity was markedly increased as compared to the parallel hole collimator, 17-fold increase for the phantom data and approximately 20-fold for the hand data. Image quality and signal-to-noise ratio of the SPECT projections were significantly improved using the EMBD algorithms. The dual-head SPECT imaging system associated with the EM-type blind deconvolution algorithms may be a preferred system for low-count SPECT imaging.