Regional Heart K42 Clearance Determined by Computer Analysis of Serial Digital Scans

Medical scanning procedures which provide a visual image of the distribution of a radioisotope in internal organs are customarily done using nuclides which emit gamma rays of relatively low energy. In the study of deeply placed organs, such as the heart, most of the radiation is absorbed or scattered by tissue located between the site of interest and the detector. Through the use of K42 (1.5 mev gamma) and heavily shielded detectors, satisfactory visualization of the regional tracer uptake in the heart muscle has been obtained. In order to separate radioactivity originating in muscle from that in the circulating blood, a regression analysis of the changes in counting rate with time at each of 960 locations was made by computer processing of serial scans.