Biological effects of ¹⁸F-FDG administration and CT dose during PET/CT: chromosomal aberrations in a two-center prospective observational study.

Objective

To assess the radiation effects of internal 18F-fluorodeoxyglucose (FDG) administration and external CT exposures during PET/CT, using reduced-dose and standard-dose CT protocols, on chromosomes in peripheral blood lymphocytes (PBLs).

Materials and methods

This prospective two-center observational study included patients undergoing clinically indicated FDG-PET/CT using different CT dose protocols. Peripheral blood was sampled at three time points: before FDG administration, after FDG administration, and after CT acquisition. Unstable chromosomal aberrations (CAs) in PBLs were quantified at each time point. Non-parametric tests were used for group comparisons, and associations between radiation dose parameters and changes in CAs were evaluated using generalized linear mixed-effects models.

Results

A total of 101 consecutive patients were enrolled in the reduced-dose protocol center (Center RD; mean age 70 ± 9 years [standard deviation], 55 men) and 56 patients in the standard-dose protocol center (Center SD; 64 ± 11 years, 31 men). The CA-evaluable population comprised 101 patients in Center RD and 55 patients in Center SD. FDG administration did not significantly increase CAs at either center. Following CT acquisition, no significant increase in CAs was observed with the reduced-dose protocol, whereas CAs increased significantly with the standard-dose protocol (Center SD: p = 0.016).

Conclusion

FDG administration had no detectable impact on CAs, whereas CT effective dose was associated with CA frequency after multivariable adjustment, with no evidence of a synergistic interaction with FDG. These findings support CT dose optimization and the use of reduced-dose CT protocols in PET/CT when clinically appropriate.

Key points

Question How do internal 18F-fluorodeoxyglucose (FDG) and external CT exposures during PET/CT affect chromosomes, and how do these effects differ between reduced- and standard-dose CT protocols? Findings Chromosomal aberrations increased after standard-dose PET/CT, and CT effective dose, but not FDG effective dose, was independently associated with chromosomal aberration frequency after multivariable adjustment. Clinical relevance CT effective dose was independently associated with chromosomal aberration frequency, while age and prior chemotherapy also influenced CA frequency. This provides biological justification for CT dose optimization and broader use of reduced-dose PET/CT when clinically appropriate.