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Polar maps have been used to assist clinicians diagnose coronary artery diseases (CAD) in single photon emission
computed tomography (SPECT) myocardial perfusion imaging. Herein, we investigate the optimization of collimator
design for perfusion defect detection in SPECT imaging when reconstruction includes modeling of the collimator. The
optimization employs an LROC clinical model observer (CMO), which emulates the clinical task of polar map detection
of CAD. By utilizing a CMO, which better mimics the clinical perfusion-defect detection task than previous SKE based
observers, our objective is to optimize collimator design for SPECT myocardial perfusion imaging when reconstruction
includes compensation for collimator spatial resolution. Comparison of lesion detection accuracy will then be employed
to determine if a lower spatial resolution hence higher sensitivity collimator design than currently recommended could be
utilized to reduce the radiation dose to the patient, imaging time, or a combination of both. As the first step in this
investigation, we report herein on the optimization of the three-dimensional (3D) post-reconstruction Gaussian filtering
of and the number of iterations used to reconstruct the SPECT slices of projections acquired by a low-energy generalpurpose
(LEGP) collimator. The optimization was in terms of detection accuracy as determined by our CMO and four
human observers. Both the human and all four CMO variants agreed that the optimal post-filtering was with sigma of
the Gaussian in the range of 0.75 to 1.0 pixels. In terms of number of iterations, the human observers showed a
preference for 5 iterations; however, only one of the variants of the CMO agreed with this selection. The others showed a
preference for 15 iterations. We shall thus proceed to optimize the reconstruction parameters for even higher sensitivity
collimators using this CMO, and then do the final comparison between collimators using their individually optimized
parameters with human observers and three times the test images to reduce the statistical variation seen in our present
results.
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