Radiation risks to lymphoma patients undergoing 18F-FDG studies

Objectives To investigate radiation risks to patients undergoing 18F-FDG studies that take into account patient age, sex, and weight.

Methods We obtained patient demographics and weights of 54 consecutive patients with lymphoma who each underwent a18F-FDG PET study. The administered activity was converted into an effective dose using the patient size dependent dosimetry data provided in ICRP Publication 80. Patient effective doses were converted into estimates of the lifetime attributable risk of cancer incidence and cancer mortality using age and sex dependent risk factors provided in BEIR VII.

Results The average patient age/weight in this study was 43 years/68 kg for males and 33 years/61 kg for females. Patient effective dose are proportional to patient weight^(-0.784) (r² >0.99). The average administered activity was 410 MBq, which resulted in an average effective dose of 8.5 mSv for males and 8.9 mSv for females. The average cancer incidence was 0.71/1,000 cases for males, and 1.27/1,000 cases for females, with cancer mortality being about half the incidence. Cancer rates for the youngest patients were an order of magnitude higher than those for the oldest patients.

Conclusions Average lifetime attributable cancer risks to lymphoma patients from a single FDG-PET study is approximately 1 per 1,000, but are strongly influenced by patient age, gender and weight. Cancer risk in younger patients is magnitude of order greater.