Phase II year
1995
(last award dollars: 1996)
Attenuation correction in positron emission tomography (PET) is usually achieved using a transmission scan, which is typically performed with one or several rotating rod sources containing a positron emitter such as Ge- 68. Since good statistics is required in the transmission scan, the imaging time is typically 10 to 20 minutes and the activity in the rod sources is as high as the scanner countrate capability permits. We will perform the transmission scan with a single gamma-ray emitter, namely Cs-137, which has an energy of 662 keV, i.e. somewhat higher so that energy discrimination can be used to separate its energy from that of a positron emitter. Since only the transmitted gamma-rays are used and the source is shielded towards the nearer detectors, higher countrates and therefore shorter transmission scan can be obtained. During Phase I, we have demonstrated that high quality transmission scans can be achieved in as little as 2 minutes.National Center for Research Resources (NCRR)