In vivo detection, localization, and measurement of radionuclides in man: a detection system for the localization and measurement of small amounts of photon emitters. Progress report, September 1, 1978-May 15, 1979

The design, construction, and testing of a photon detection system which will yield, simultaneously, information proportional to both the magnitude and location of sources of radioactivity were undertaken. The operating principle of the detector system, active collimation, allows spatial resolution by utilizing the crystal elements themselves as the collimating device; hence a greater counting efficiency is attainable than with other currently available systems. The differences in characteristics of various crystals are utilized as the means of separating events occurring in each of five crystals. Mathematical processing of the counts from the individual crystals is then employed in conjunction with their geometric relationship to develop both positional data and to quantify the amount of radioactivity. By utilizing crystal detector elements in an active collimation configuration and incorporating them in an array which permits these crystals to be alternately advanced and retracted in a programmed, ordered manner, a high degree of spatial resolution is believed achievable without unduly compromising system sensitivity. Experiments were planned with a detector of optimized design to provide data on the ultimate performance that can be achieved with an N-element detector array. The experiments include development of the optimal crystal configuration, studies to ascertain the most efficient crystal shape, and the evolving of data processing techniques to translate detector response into precise source position information