Geometric efficiency and other performance characteristics of focusing collimators

The geometric efficiency of a focusing collimator is calculated directly at the focal plane and the significance of this parameter of collimator performance is discussed. The signal and noise for different collimator parameters is calculated neglecting septa penetration. The dependence of optimal collimator design upon the geometric size and environment of the radioisotope inhomogeneity being sought is examined in some detail. A criterion for lesion detectability is formulated which is based upon areal comparisons and which seeks to exhibit explicitly the statistical probabilities of false positive and false negative interpretations.