Approximate method for acquisition and reconstruction of volumetric PET data

• Main Authors: Cutler, PDuffy, Luk, Paul, Dahlbom, Magnus, Digby, Ward M
• Format: Conference Proceeding
• Language: English

A preliminary evaluation of a technique for rapid acquisition and reconstruction of volumetric PET data with the ECAT EXACT 921 PET system is presented. Data are collected with septa removed to collect all possible coincidence combinations, thereby achieving maximum sensitivity, and reconstructed only approximately using 2D filtered back projection. The primary goals are to reduce the scan time and to generate image results before the patient leaves the PET facility. The sensitivity advantage over conventional 2D acquisition is measured to be a factor of 1.4 to 2.4 in useful counts depending on the axial acceptance angle ( alpha ) used. For reconstruction, volumetric coincidence data are rebinned in the axial direction into parallel transaxial sinograms. Images are reconstructed using a standard 2D filtered back projection. This approximate approach provides a large advantage in reconstruction and processing time, a factor of 15 faster than full 3D back-projection, and avoids the need for specialized reconstruction hardware. Raw data arrays generated are identical to that for 2D data collection. Reconstructed axial resolution is markedly degraded compared with 2D images, reaching 28 mm FWHM near the edge of the FOV. In addition,, partial volume effects are evident in this region. Image results near the center of the FOV are acceptable. These factors will limit the application of this technique to brain imaging and whole-body studies, where rapid, qualitative images are needed.