Reconstruction of attenuation maps for a PET/MR scanner based on the LSO background activity

The majority of all modern PET cameras use LSO and LYSO crystals which contain a small proportion of the radioactive isotope of Lutetium. The aim of this study is to obtain attenuation maps for dedicated head PET/MR scanners based on the background activity of the LSO scintillator. In particular, attenuation maps for the Tx/Rx coils in the PET Field of View have to be provided. Before reconstructing such an attenuation map, the scanners stability with respect to detector temperature and background count rate was examined. First image reconstructions of the 8-channel Tx/Rx head coil and a 3-rod phantom obtained with LSO background prove that the method is feasible as long as the overall scan time is sufficiently long.