Effects of optimization of injection dose on image quality and radiation exposure dose in FDG PET tests.

3017 Objectives: The injection dose affects the image quality and radiation exposure dose in 18F-FDG PET tests. In this study, we optimized injection dose by adjusting it by patient’s body weight and examined the effects of this optimization on image quality and exposure dose in FDG PET tests by analyzing a large number of actual patients’ data using newly developed dose management software that complies with international standards. Methods: The data of 1,771 patients were retrospectively analyzed using the dose management software, onti™ (RYUKYU-ISG, Kyoto, Japan). The injection dose was fixed to 240 MBq for 846 patients and that was adjusted to 3.7 MBq/kg-body weight for 925 patients. Image quality was evaluated by noise equivalent countdensity (NECdensity) calculated excluding the counts of brain and bladder. Exposure dose was obtained using the rate of 0.019 mSv/MBq based on the report in ICRP publication 106. NECdensity and radiation exposure dose of the fixed and adjusted groups of patients were compared. Results: The optimization of injection dose changed the injection dose, NECdensity and radiation exposure dose from 239.9 ± 6.83 MBq, 0.39 ± 0.1 and 4.56 mSv to 213.0 ± 39.9 MBq, 0.42 ± 0.2 and 4.04 mSv, respectively. The adjustment of injection dose by body weight statistically significantly improved of image quality evaluated using NECdensity and radiation exposure dose by 8% and 11%, respectively (p Conclusions: By analyzing a large number of patients’ data using onti™, we demonstrated that the optimization of injection dose could contribute to the improvement of image quality and radiation exposure dose in 18F-FDG PET tests.