OPTIMIZATION OF A PINHOLE COLLIMATOR IN A SPECT SCINTILLATING-FIBER DETECTOR SYSTEM - A MONTE-CARLO ANALYSIS

Monte Carlo simulations were used to optimize the dimensions of a lead pinhole collimator in a SPECT system consisting of a line of equally spaced Tc-99m point sources and a plastic scintillating fiber detector. The optimization was performed by evaluating the spatial resolution and scanner sensitivity for each source distribution location and collimator parameter variation. An optimal spatial resolution of 0.43 cm FWHM was observed for a source distribution positioned 2.0 cm from the collimated scintillating fiber detection system with a pinhole radius of 1.0 mm and a collimator thickness of 3.0 cm for a 10,000 emission photon simulation. The optimal sensitivity of 257 cps/MBq (7704 cps/mCi) occurred for a source distance of 2.0 cm, a radius of 3.0 mm and a thickness of 3.0 cm.