  The Dynamic Cardiac SPECT (DC-SPECT) system is being developed at the
Massachusetts General Hospital, featuring a static cardio focus asymmetrical
geometry enabling simultaneous high resolution and high sensitivity imaging.
Among 14 design iterations of the DC-SPECT with varying number of detector
heads, system sensitivity and system resolution, the current version being
fabricated features 10 mm FWHM geometrical resolution (without resolution
recovery) and 0.07% sensitivity; this is 1.5x resolution gain and 7x
sensitivity gain compared to a conventional dual head gamma camera. This work
presents improvement in imaging resolution by implementing a spatially variant
point spread function (SV-PSF) with list mode MLEM reconstruction. A resolution
recovery method by PSF deconvolution is validated on list mode MLEM
reconstruction for DC-SPECT. A spatial invariant PSF is included as an
additional test to show the influence of the accuracy of PSF modelling on the
reconstructed image quality. We compare the MLEM reconstruction with and
without PSF deconvolution; an analytic model is used for the calculation of
system response, and the results are compared to Monte Carlo (MC) based
methods. Results show that with PSF modelling applied, the quality of the
reconstructed image is improved, and the DC-SPECT system can achieve a 4.5 mm
central spatial resolution with average 795 counts/(s*Mbq). The results show
substantial improvement over the gold standard GE Discovery 570c performance
(spatial resolution 7 mm with an average 460 counts/s*MBq, central resolution
5.8 mm). The impact of PSF deconvolution is significant, and the improvements
of the reconstructed image quality is more evident compared to MC simulated
system matrix with the same sampling size as in simulation.
