The sources of overestimation in the quantification by SPECT of uptakes in a myocardial phantom: concise communication.

A single photon emission computerized tomographic (SPECT) system's overestimation of the tracer concentration in a myocardial perfusion defect was examined by physical phantom studies. An empirical attenuation correction was used to isolate the problem of overestimation from imperfect attenuation correction. The overestimation of defect concentration in our SPECT system was found to come from three sources: software error, finite spatial resolution of the system, and scattered photons generated inside the phantom. The findings confirmed the current belief that the two major problems remaining in quantification with the SPECT technique are attenuation correction and scatter correction.