CHARACTERIZATION OF SAMPLING SCHEMES FOR WHOLE-BODY PET IMAGING

Whole body PET images suffer from relatively high noise levels due to inherently poor counting statistics in the emission data. Optimization of acquisition parameters is essential, to minimize any additional noise contamination. It has previously been shown that by using a continuous or redundant axial sampling scheme, a reduction in statistical noise and improvement in image quality are possible. In this work, the continuous axial sampling technique is further characterized and compared to the conventional step-and-shoot technique. The main source of additional noise contamination with conventional sampling is the detector sensitivity normalization procedure which is applied to the emission data. With continuous axial sampling and a single normalization matrix for all planes, the statistical noise in the normalized factors is reduced by factor close to the number of planes in the scanner. The continuous sampling technique is shown to be less sensitive to small patient movements (<5 mm) compared to conventional sampling. Previously reported problems of data handling have been resolved by rewriting the acquisition firmware to allow on-line addition of the redundant sampled data in hardware.