The effect of abdominal contrast-enhanced CT on DNA double-strand breaks in peripheral blood lymphocytes: an in vitro and in vivo study.

Background: As abdominal computed tomography (CT) radiation dose can be higher compared with other organ systems, monitoring the radiation exposure from this exam type is especially important.

Purpose: To evaluate the effect of abdominal contrast-enhanced CT (CE-CT) on levels of DNA double-strand breaks (DSBs) in peripheral blood lymphocytes.

Material And Methods: This study was performed in two parts: (i) an in vitro study: venous blood samples from 12 volunteers were divided into four groups. Samples in group A did not undergo radiation exposure, while groups B, C, and D received one CT scan with 1-3 times the radiation dose equivalent to abdominal CE-CT scan, respectively; and (ii) an in vivo study: blood was taken before CT and 5 min after CT in 30 patients. Lymphocytes were isolated and stained by immunofluorescence of γ-H2AX protein. DSB levels were compared by variance analysis or paired t-test. The relationship between radiation dose and γ-H2AX focus increase was analyzed using Pearson correlation analysis.

Results: In the in vitro study, DSBs levels in groups B, C, and D were 49.4%, 96.6%, and 149.4% higher than those in Group A, respectively (all P < 0.001). Radiation dose in the four subgroups had a linear correlation to DSB levels ( P < 0.001). In the in vivo study, the DSB level was 43.5% higher after CT ( P < 0.001).

Conclusion: Abdominal CE-CT significantly increased DSB levels in both in vitro and in vivo experiments. A positive linear correlation of CT radiation dose with intracellular DSBs levels was observed in the in vitro study.