Abstract
Long axial field of view (LAFOV) PET/CT scanners (> 1 m axial FOV) provide an order of magnitude higher system sensitivity compared with conventional scanners. This creates opportunities for significant radiation dose reductions for patients, without loss of diagnostic image quality or increased scan time. This study aimed to investigate changes in radiation dose received by patients undergoing whole-body [(18)F]FDG PET/CT studies at a metropolitan hospital following the transition from the Siemens Biograph mCT (21.8 cm axial FOV) to the Siemens Biograph Vision Quadra LAFOV PET/CT (106 cm axial FOV). For the mCT and Quadra, 484 and 554 patient studies were reviewed, respectively. The radiation dose from the PET component was derived from the recorded FDG dose, calculated based on ICRP recommendations, and scaled to patient weight. The CT dose was derived from the dose-length product. The median effective dose from the PET component for the mCT and Quadra was 6.2 (IQR 5.5-6.9) and 2.9 (IQR 2.8-3.6) mSv, respectively, and 5.7 (IQR 5.1-6.5) and 2.8 (IQR 2.4-3.4) mSv, respectively, when scaled to patient weight. The median effective dose from the CT component for the mCT and Quadra was 7.7 (IQR 6.2-9.4) and 7.6 (IQR 5.9-9.4) mSv, respectively. The total median effective dose combining PET and CT components for the mCT and Quadra was 13.9 (IQR 12.4-15.7) and 10.5 (IQR 9.4-12.3) mSv, respectively, and 13.5 (IQR 12.4-15.0) and 10.3 (IQR 9.3-11.9) mSv, respectively, when scaled to patient weight. While the effective dose from PET was approximately halved due to reduced injected activity, the CT effective dose remained relatively unchanged and is now the dominant source of radiation dose to the patient for LAFOV PET/CT.