A BOUND ON THE ENERGY RESOLUTION REQUIRED FOR QUANTITATIVE SPECT

Scattered radiation is one of several physical perturbations that limi t the accuracy of quantitative measurements in single-photon emission computed tomography (SPECT). Improvement in detector energy resolution leads to a reduction of scatter counts and a corresponding improvemen t in the quantitative accuracy of the SPECT measurement. In this study , simulated SPECT projections of a simple myocardial perfusion phantom were used to investigate the effect of detector energy resolution on the data. The phantom consists of a spherical shell of radionuclide wi thin a 15 cm radius water-filled cylinder. Each projection contains on the order of 3 x 10(5) counts. The results demonstrate that a full-wi dth, half-maximum energy resolution of 3-4 keV is sufficient to render the error due to scatter insignificant compared to the uncertainty du e to photon statistics in this case. Further simulations verify that b ecause smaller objects produce less scatter, they can be imaged accura tely with degraded energy resolution. These results are useful when de signing prototype systems that utilize solid-state detectors and low-n oise electronics to achieve improved energy resolution. (C) 1996 Ameri can Association of Physicists in Medicine.