BIOKINETIC and DOSIMETRIC ASSESSMENT of FLUORINE 18 in HEALTHY VOLUNTEERS SUBJECTED to 1 8 F-NaF PET/CT BONE SCANS VIA COMPARTMENTAL/MATLAB MODELS and IN-VIVO STUDY

Objective: This study quantified the time-dependent concentration of 18F-NaF in critical organs according to a simplified compartmental biokinetic model with clinical verification. Methods: The eleven volunteers were given 232.9±33.8MBq 18F-NaF administration, then scanned (with 15min-collection, every 20min, for 200 consecutive min) with a Philips Gemini GXL PET/CT. The empirical data were collected and normalized as the input dataset for MATLAB program. A six-compartmental model was created as a set of time-dependent differential equations and analyzed by the MATLAB to optimize the correlation between the in vivo data and calculated results. The six compartments were: body fluid, bone, kidney, liver, remainder and excretion, while kidney and liver compartments were conventionally split into two subunits with different half-lives to fit properly the empirical data. Results: The average biological half-lives of body fluid, bone, kidney-1, kidney-2, liver-1, liver-2 and the remainder (rest of body) were assessed as 577±150, 770±255, 138±64, 25±6, 138±29, 33±9, and 84±23min, respectively. A dimensionless AT index of disagreement between the empirical data and MATLAB optimal solutions was proposed of validating the applied acquisition system and analytical method feasibility. The body fluid and bone AT values did not exceed 20%. The proposed refined equation yielded the internal dose from both gamma- and beta-rays (0.409±0.076 cSv as 0.00176±0.00033 cSv/MBq), which exhibited good correlation with literature (0.00168-0.00270 cSv/MBq). Conclusion: The proposed MATLAB-based fitting of in-vivo data with the theoretical results was instrumental for assessing the radiation dose received by the PET/CT bone scan participants.