Effective Dose Estimation with IDAC and OLINDA for ¹⁸F-FDG and ⁶⁸Ga-PSMA PET/CT Procedures

Internal dosimetry is a part of radiation safety for patients and radiation workers in nuclear medicine procedures. This study retrospectively determined the effective dose for oncology patients undergoing PET/CT scans by using widely used computer codes, and the results were compared with each other and literature. The study focused on the radiopharmaceuticals ¹⁸F-FDG (n = 220) and ⁶⁸Ga-PSMA (n = 85), administered to 305 patients for cancer imaging at Yeditepe University Kosuyolu Hospital's nuclear medicine department. PET dose was calculated using OLINDA/EXM, IDAC-Dose 1.0 and IDAC-Dose 2.1 programs while ImPACT software was used to determine the effective dose from the CT scan. All effective doses were derived in accordance with ICRP 60 and ICRP 103 tissue weighting factors. PET effective doses from highest to lowest were calculated with OLINDA/EXM, IDAC-Dose 1.0, IDAC-Dose 2.1 (ICRP 60) and IDAC-Dose 2.1 (ICRP 103) as 9.96, 9.07, 7.01, 6.28 mSv respectively for ¹⁸F-FDG. The highest PET effective dose was also calculated with OLINDA/EXM software as 3.65 mSv for ⁶⁸Ga-PSMA. For the total effective dose in PET/CT scans, CT contributed about 92% for ⁶⁸Ga-PSMA protocol and 75% for ¹⁸F-FDG protocol. Key words: effective dose; internal dosimetry; ¹⁸F-FDG; ⁶⁸Ga-PSMA; OLINDA/EXM; IDAC Dose 2.1; IDAC-Dose 1.0;