Noise characteristics of a SPECT simulation system

The noise characteristics of synthetic images generated by a Monte Carlo SPECT simulation package (Sim-SPECT) were examined. Sim-SPECT generates single planer projections via analog Monte Carlo methods but uses a directional photon cloning technique to simulate tomographic acquisition. Statistical noise characteristics were investigated in both single planar projection and tomographic acquisitions, the latter to assess the potential noise distortion of the directional cloning algorithm. The root-mean-square (EMS) and the noise power spectrum were two mathematical measures used to characterise the noise. NPS was estimated using spectral averaging techniques. Synthetic Sim-SPECT and experimental data (both single planar and tomographic acquisitions) were obtained using phantoms of identical dimensions and uniform activity.<>