Comparison of gamma (Anger) camera systems in terms of detective quantum efficiency using Monte Carlo simulation

Abstract

The aim of the present study was to perform an extensive evaluation of available gamma camera systems in terms of their detective quantum efficiency (DQE) and determine their dependency on relevant parameters such as collimator type, imaging depth, and energy window using the Monte Carlo technique. The modulation transfer function was determined from a simulated (99m)Tc point source and was combined with the system sensitivity and photon yield to obtain the DQE of the system. The simulations were performed for different imaging depths in a water phantom for 13 gamma camera systems from four manufacturers. Except at very low spatial frequencies, the highest DQE values were found with a lower energy window threshold of around 130 keV for all systems. The height and shape of the DQE curves were affected by the collimator design and the intrinsic properties of the gamma camera systems. High-sensitivity collimators gave the highest DQE at low spatial frequencies, whereas the high-resolution and ultrahigh-resolution collimators showed higher DQE values at higher frequencies. The intrinsic resolution of the system mainly affected the DQE curve at superficial depths. The results indicate that the manufacturers have succeeded differently in their attempts to design a system constituting an optimal compromise between sensitivity and spatial resolution.