Internal dosimetry in F-18 FDG PET examinations based on long-time-measured organ activities using total-body PET/CT: does it make any difference from a short-time measurement?

Abstract Purpose A 2-m axial field-of-view, total-body PET/CT scanner (uEXPLORER) has been recently developed to provide coverage and ultra-high sensitivity, which together, enables opportunities for in vivo time-activity curve (TAC) measurement of all investigated organs simultaneously with high temporal resolution. This study aims at quantifying the cumulated activity patient dose 2-[F-18]fluoro-2-deoxy-D-glucose (F-18 FDG ) imaging by using delayed curves (TACs), measured out 8-h post-injection, different so that comparison between approaches short-time method (up 75 min post-injection) or long-time 8 h could be performed. Methods Organ TACs 10 healthy volunteers were collected 4 periods after intravenous injection F-18 FDG. The post-injection 6 source fitted a spline (based on Origin (version 8.1)). To compare estimated from spline-fitted curves, multi-exponential was also calculated. Exponential shorter series data consistent clinical procedure previous dosimetry works. An dynamic bladder wall model considering 2 voiding employed illustrate differences caused durations. absorbed doses further Medical Internal Radiation Dose (MIRD) voxel phantoms. Results lead significant bias liver compared long-time-measured method, 18.38% average. For myocardium, difference not statistically due large variation metabolism among individuals. average residence time brain, heart, kidney, liver, lungs 8.38%, 15.13%, 25.02%, 23.94%, 16.50% methods. Regarding effective dose, maximum short-time-measured 9.93%. When revealed most up 21.18%. calculated 13.79% larger than two-voiding model, least 50.17% lower studies based fixed content volume. Conclusions Long-time multi-organ resolution enabled demonstrated 20 PET scan 1 used retrospective analysis organs. As contributed recommended estimation.