Evaluation of projection pixel-dependent and pixel-independent scatter correction in SPECT

Dual energy window scatter subtraction methods in single photon emission computed tomography (SPECT) to compensate for the detection of Compton-scattered photons are based on the assumption that the number of scattered photons detected by each projection pixel in the primary energy window is proportional to the number of photons detected in a secondary energy window. The reliability of this assumption was tested using Monte Carlo modeling of photon detection kernels for photon emission by Tc-99m within a water-filled cylinder. By fitting the scatter kernels of a primary energy window to the kernels of a secondary energy window, scatter correction factors were obtained which were dependent on the location of the projection pixel in the detector array. A simultaneous fit of kernels at all detector locations was performed to obtain pixel-independent scatter correction factors. A numerical experiment with noise-free projection data to test the quantitative accuracy of SPECT images reconstructed with pixel-independent and pixel-dependent scatter correction factors is described