A comparison of count rate parameters in gamma cameras.

Pulse pile-up is a fundamental problem that limits the ability of a gamma camera to produce high quality images at high count rates. Pulse pile-up results in loss of events and spatial distortions in the image. The question asked in this study is how well do some of the test procedures for measuring count rate performance in gamma cameras compare. In four gamma cameras we compared measurements of spectral fraction, count-rate curve, pulse-pair resolution, deadtime, maximum count rate, full width at half maximum of the line spread function, and misplaced event count rate. The results indicated that no one technique provides a complete description of the count-rate effects in gamma cameras. The misplaced-event measurements provided the most information.