Single photon scatter compensation by photopeak energy distribution analysis

Scattered photons degrade nuclear medicine image contrast and resolution, and preclude simple attenuation corrections. Current scatter correction methods utilize detected events with energies below pulse height analyzer (PHA) window levels, making attenuation corrections source position dependent. This new scatter rejection technique analyzes only the photon signals occurring within the range of standard PHA windows. In real time, at each image location the PHA window energy distribution is analyzed, a scatter fraction determined, and a scatter corrected number of events are output. The method can be adapted to any imaging system which produces event location and energy signals. Attenuation corrections (u=0.15 cm(-1), 140 keV) are within 6% for 2-10 cm depths.