Medical Criteria for the Design of a Dynamic Positron Tomograph for Heart Studies

Design criteria for positron emission tomography are based on the accumulated experiences of PET studies with available instruments, anatomical and physiological characteristics of the thorax and abdomen, and feasible medical science objectives which can be attained with known technology. The system should be capable of simultaneously imaging seven or more planes with 10 mm axial and 7 mm or less transverse resolution. The design of a positron tomograph for the human heart differs from that for the head because the heart and lungs are moving and attenuation from the thorax is great. Studies of myocardial blood flow and metabolism require the simultaneous measurement of tracer concentration in the myocardium and arterial input. Gated data at 5 sec intervals are required for the input function. Complete sampling of 70-100 msec phases of the cardiac cycle precludes gantry motion. The crystal choice, coupling, and electronics should allow data collection rates per image level of 100,000 events per sec with < 50% accidentals. Transmission measurements should be accomplished in 5 minutes with at least 107 events per level for adequate attenuation compensation.