An Attenuation Correction Method for Respiratory-Gated PET/CT Image

Previously we have proposed a motion correction method for avoiding both motion blur and image noise in respiratory-gated lung SPECT images [Ue, et al., 2005][ Ue, et al., 2006]. In a PET/CT system, attenuation correction can be achieved by making an attenuation map from a CT image. In PET/CT system using respiratory-gated PET, however, when a CT image acquired under a breath-hold condition is used for attenuation correction of PET in different respiratory phase, voxel values of the reconstructed PET image may be incorrect, especially in a region that has large respiratory motion. In this paper, we propose an attenuation correction method for this case. The effectiveness of the proposed method was tested using the 4D-NCAT phantoms [Kinahan, et al., 1998] and a marked stability in the voxel values around the diaphragm was observed. The proposed method was also applied to clinical data.