부산대학교 도서관

The high sensitivity, increased volume of crystal material, and improved timing resolution in the current generation of PET scanners has led to increased interest in developing CT–less attenuation correction using the lutetium background radiation. In this work, the background radiation from the radionuclide 176 Lu in the LYSO scintillators was used to estimate the attenuation map for PET attenuation correction (AC) in a recently-developed brain-dedicated PET scanner, the NeuroEXPLORER (NX). The proposed method was evaluated using a NEMA NU2 image quality (IQ) phantom dataset and a human subject scan performed on the NX. The lutetium-based AC from the cold IQ phantom was compared to the CT-based AC. Non-local means (NLM) filtering was also applied to improve the estimate of attenuation maps. The contrast of the six hot spheres and the centered cold volume were analyzed. Lutetium-based AC outperformed the non-AC images of the IQ phantom with 10% bias compared to CT-based AC. This bias is mostly due to the lack of scatter correction in the transmission reconstruction. The NLM smoothing provided higher contrast in the hot spheres and improved quantitation. Lutetium-based attenuation map of a human subject scan demonstrated good image quality in the soft tissue, skull, and air cavities in the nasal, paranasal, and tracheal regions. The results demonstrate the feasibility of using lutetium background radiation for CT-less AC in the NeuroEXPLORER.