Effective dose and risk assessment in 18F-FDG PET/CT examinations of lymphoma patients using updated dose coefficients.

[PURPOSE] The objective of this study was to estimate the total effective dose using the updated dose coefficient, and assess the associated cancer risk from radiation exposure in patients undergoing positron emission tomography (PET)/computed tomography (CT) for lymphoma indications.

[METHODS] This study included 103 patients who underwent FDG-PET/CT. The effective radiation doses to the body was calculated by summing the contribution from internal dosimetry, using the updated dose coefficients based on the ICRP approach, and external dosimetry, using the NCICT software. Based on the effective organ doses and utilizing the risk model introduced in the Biological Effects of Ionizing Radiation VII report, the lifetime attributable risk for cancer incidence (LARCI) and mortality (LARCM) were estimated on an organ-specific basis.

[RESULTS] The mean effective dose was 12.4 ± 2.8 mSv (range, 5.1-20.2 mSv), with CT contributing for 74% of the total dose. The LARCI and LARCM values varied by age and sex, with the most pronounced age-related declines observed in the uterus, ovary, and breast for female LARCI (R = 0.83, 0.80, and 0.75, respectively) and in the liver, stomach, and colon for male LARCI (R = 0.71, 0.64, and 0.60, respectively). Similarly, the strongest associations for LARCM were found in the breast, uterus, and ovary for females (R = 0.75, 0.75, and 0.73, respectively) and in the stomach and liver for males (R = 0.66 and 0.63, respectively).

[CONCLUSION] PET/CT scans involve radiation exposure that varies with age and sex, posing higher risks to radiosensitive organs especially at younger ages.