The use of X-ray CT for attenuation correction of PET data

This paper presents the results of evaluating the use of X-ray CT data for attenuation correction of PET data. This method of attenuation correction is intended for use with a combined volume-imaging PET/CT scanner for oncology, particularly of the thorax and abdomen. We discuss four possible methods of scaling the attenuation map from the CT energies of 70-100 keV to the required PET attenuation map at 511 keV. Results are presented on the testing of two of these methods (scaling and segmentation methods) with data acquired from separate PET and CT scans of a phantom with regions of different densities. We show that these two methods provide accurate results for the reconstructed PET emission scan. We also propose a hybrid scaling/segmentation method that is expected to work well in practice, based on the demonstrated results for the scaling and segmentation methods. >