DLP, blood dose, effective dose and DNA damage were analyzed for patients undergoing a thoracic or abdominal contrast CT scan on two CT scanners with different dose settings. The DNA damage was assessed by scoring 纬-H2AX foci representing DNA double-strand breaks (DSBs) in patient's lymphocytes. Blood dose was calculated using the ImPACT software.
The CT system operating at higher dose settings represented by higher DLP values, resulted in a significantly higher number of radiation-induced 纬-H2AX foci in patient's lymphocytes (DLP: 2.1 times higher; 纬-H2AX foci: 2.3 times higher; p < 0.05). Plotting 纬-H2AX foci versus blood dose showed a systematic increase of DNA damage with dose. In vitro experiments ruled out a possible X-ray enhancement of DNA damage effect by contrast agent.
Present study demonstrates that optimization of DLP setting of scanners results in a reduction of X-ray effects in patients.