The Effect of Improving Energy Resolution on Gamma Camera Performance: A Quantitative Analysis

The Modulation Transfer Functions (MTF) of two commercial cameras and of a single element germanium camera fitted with different collimator configurations have been studied theoretically and experimentally in order to separate the different elements which contribute to the imaging capabilities of a gamma camera. Effects due to size and shape of collimator holes, and to positron range at 511 keV have been treated as filtering functions, predicting the behavior of a camera quite accurately. The effect of energy resolution has then been studied by noting the changes in MTF and the corresponding changes in the computer generated image of a low contrast circularly symmetric phantom as a function of energy resolution. The possibility of excellent imaging under low contrast situations with high-energy resolution detectors is demonstrated, and the required penalty in camera speed is documented.