TRIPLE GAMMA COINCIDENCE TOMOGRAPHIC IMAGING WITHOUT IMAGE PROCESSING.

An imaging system using the electronic collimation of thin-thick planar detector stacks for coincidence detection of three or more nuclear gamma rays emitted from an isotope in cascade is proposed. Although the probability of detecting a triple-photon coincidence (TPC) event is quite low, it may be possible, based on the quantitative analysis described here, to screen 7. 5 multiplied by 10**5 coincidence events over a 10-min period (corresponding to a 1 mC//i patient dose uniformly distributed over a cylindrical water phantom (CWP) with size of radius approximately equals 5. 25 cm and length approximately equals 17 cm). These TPC events may be sufficient to reasonably evaluate the radioisotope concentration distributed within the CWP in 1. 5 multiplied by 10**4 patient tissue voxels, each of volume less than 0. 5 cm**3.