Implementation of quantitative 3D PET

Following previous reports of the NEC gain for a PET (positron emission tomography) scanner with retractable septa (Siemens-CTI 953B), methods for 3-D normalization and attenuation correction from 2-D datasets were developed. Physical performance and system calibration were reevaluated for 3-D reconstructed data for this scanner. Normalization is performed by measuring the direct plane sinograms (no cross-plane contribution) with septa in place and then effectively calculating the sensitivity for individual detectors. 3-D normalization factors are then the product of any two detectors´ individual responses. To overcome the axial variation in sensitivity inherent in a 3-D system, interplane sensitivities are normalized to the sensitivity of the 2-D planes. This results in a system sensitivity of approximately=12.5 kcps-MBq/sup -1/, although the true value is over eight times greater in the central planes than at the edges. Over 50 patients had 3-D PET studies for a wide range of radiotracers labeled with /sup 15/O, /sup 11/C, and /sup 18/F. CBF visual activation studies demonstrated significant results in a single individual. Dynamic /sup 18/F-DG studies have yielded improved quantitative data from 3-D.<>