Validation of SIMIND Monte Carlo Simulation Software for Modelling a Siemens Symbia T SPECT Scintillation Camera

The use of Monte Carlo (MC) simulations in nuclear medicine is on the rise due to its usefulness in modelling many physical phenomena which are difficult or impossible to measure. To use MC for gamma camera image simulations, it is important to validate the simulated data with the measured data to ensure that what is simulated is a true representation of the physical system being modelled. Therefore, in this study, the SIMIND MC code for modelling a Siemens Symbia T dual head SPECT/CT gamma camera fitted with high energy all-purpose collimators (HEAP) was validated. The validation was done by acquiring and simulating certain NEMA stipulated performance measurements for I-131. These measured and simulated performance data were processed and the results compared. The FWHM and FWTM for the gamma camera for measured and simulated system spatial resolution were 14.4, 29.7 mm versus 13.9, 25.9 mm. System sensitivity performance measurements and simulation produced results of 49 cps/MBq and 48 cps/MBq respectively. The corresponding measured and simulated values for the septal penetration were 3.8 and 4.2%. From this study it is evident that the SIMIND MC Code can be used with confidence to mimic I-131 studies acquired with a Siemens Symbia T SPECT/CT gamma camera fitted with HEAP collimators.