MONTE-CARLO AND EXPERIMENTAL EVALUATION OF ACCURACY AND NOISE PROPERTIES OF 2 SCATTER CORRECTION METHODS FOR SPECT

Scatter correction is a prerequisite for quantitative SPECT, but poten tially increases noise. Monte Carlo simulations (EGS4) and physical ph antom measurements were used to compare accuracy and noise properties of two scatter correction techniques: the triple-energy window (TEW), and the transmission dependent convolution subtraction (TDCS) techniqu es. Two scatter functions were investigated for TDCS: (i) the original ly proposed mono-exponential function (TDCSmono) and (ii) an exponenti al plus Gaussian scatter function (TDCSGauss) demonstrated to be super ior from our Monte Carlo simulations. Signal to noise ratio (SIN) and accuracy were investigated in cylindrical phantoms and a chest phantom . Results from each method were compared to the true primary counts (s imulations), or known activity concentrations (phantom studies). Tc-99 m was used in all cases. The optimized TDCSGauss method overall perfor med best, with an accuracy of better than 4% for all simulations and p hysical phantom studies. Maximum errors for TEW and TDCSmono of -30 an d -22%, respectively, were observed in the heart chamber of the simula ted chest phantom. TEW had the worst SIN ratio of the three techniques . The SIN ratios of the two TDCS methods were similar and only slightl y lower than those of simulated true primary data. Thus, accurate quan titation can be obtained with TDCSGauss, with a relatively small reduc tion in S/N ratio.