The SimSPECT photon selector and multiple angular sampling of photons

The authors have previously developed a Nuclear Medicine simulation package called SimSPECT. It uses analog Monte Carlo and therefore results in very large CPU consumption. To maximize the use of each simulation, the authors have recently developed XYZ SimSPECT, which stores the origin of every detected photon. For example, an extended source, or hot bath, can be simulated with XYZ SimSPECT. A post-simulation photon selector keeps only the photons that originated in the source geometry of interest. To increase the number of detected photons in a tomographic simulation, the authors use Multiple Angular Sampling (MAS). In this approach, the origin of the source geometry is rotated by an angle P. If the photon is now included in the source geometry, it is added to the new projection file (α1+β1). Therefore, the photon selector allows the authors to “simulate” an infinite variety of source geometries for a single CPU-intensive run and the use of MAS increases the number of detected photons per simulation. The authors demonstrate, in this paper, their use of 1) XYZ SimSPECT with the photon selector and 2) MAS in their study of the detection of focal arterial lesions