Biological Effects of Low-Dose Chest CT on Chromosomal DNA

Area of Science:

• Radiology and Imaging
• Radiation Biology
• Molecular Genetics

Background:

• The National Lung Screening Trial demonstrated reduced lung cancer mortality with low-dose (LD) CT chest examinations.
• However, the biological impact of radiation exposure from LD CT remains incompletely understood.
• This study investigates the genotoxic effects of LD CT versus standard-dose (SD) CT.

Purpose of the Study:

• To compare the effects of LD CT and SD CT on DNA double-strand breaks (DSBs) and chromosome aberrations (CAs).
• To assess the biological consequences of radiation exposure from different CT dose levels in peripheral blood lymphocytes.

Main Methods:

• Prospective enrollment of 209 participants undergoing chest CT.
• Quantification of γ-H2AX foci (DSBs) and unstable CAs using immunofluorescence and FISH.
• Comparison of pre- and post-CT measurements using the Wilcoxon signed rank test.

Main Results:

• SD CT (median effective dose 5.0 mSv) significantly increased DSBs and CAs (P < .001 and P = .003, respectively).
• LD CT (median effective dose 1.5 mSv) showed no significant difference in DSBs or CAs before and after the examination (P = .45 and P = .69, respectively).
• Participant demographics and body size were similar between LD CT and SD CT groups.

Conclusions:

• Low-dose CT examinations did not induce detectable DNA damage in human peripheral blood lymphocytes.
• Standard-dose CT examinations resulted in measurable increases in DNA double-strand breaks and chromosome aberrations.
• Findings suggest a safer biological profile for LD CT in the context of radiation exposure.