Comparison of the differential attenuation method for multi-emission SPECT with conventional methods of attenuation compensation

The Differential Attenuation Method (DAM) was developed to simultaneously estimate activity and attenuation distributions from multi-emission projection data alone. Previously, DAM was shown to improve the quality and quantitative accuracy compared with filtered-backprojection without attenuation compensation. Here, that work is extended by comparing the performance of DAM to an iterative penalized-weighted least-squares reconstruction with: (1) uniform attenuation, and (2) the true attenuation. A single-slice numerical torso phantom was used to simulate data from ²⁰¹Tl cardiac studies. Noise-free projections and data with additive Poisson-distributed noise were simulated with and without a myocardial perfusion defect. Scatter was not simulated. Images reconstructed with DAM from data at realistic count densities were more accurate than those reconstructed with an assumed uniform attenuation distribution, and nearly as accurate as those obtained using the true attenuation distribution