Biological effects of radiation exposure during endovascular aortic aneurysm repair

Health risks associated with ionising radiation is a growing concern. Fluoroscopically guided interventions such as endovascular aortic repair (EVAR) is associated with radiation exposure, particularly thoracoabdominal repairs using branched and/or fenestrated stent grafts. Conventional methods of measuring radiation exposure such as personal dosimeters or dose area product (DAP) do not give a true reflection of the biological effect of radiation exposure. In contrast, bio-dosimetry directly measures the effects of radiation exposure in biological specimens such as circulating lymphocytes, which are sensitive to radiation exposure and exhibit upregulation of DNA damage biomarkers such as γ-H2AX when exposed to ionising radiation (Beels, et. al., 2009) This study aimed to measure DNA damage/repair biomarkers in patients and operators after radiation exposure associated with EVAR. The expression of DNA damage/repair markers, γ-H2AX and phosphorylated ataxia telangiectasia mutated (pATM), was quantified in circulating lymphocytes in patients and operators during the peri-operative period of endovascular repair and compared with open aortic repair using flow cytometry. The role of leg shielding in radiation protection was assessed separately measuring these markers in the same operators wearing leg lead shielding and compared with those operating with unprotected legs. Susceptibility to radiation damage was determined by irradiating operators' blood in vitro. γ-H2AX and pATM levels increased significantly in patients and operators immediately after EVAR and recovered after 24 hrs. There was no change in γ-H2AX or pATM expression after open repair. Leg protection abrogated γ-H2AX and pATM response after branched endovascular aortic repair/fenestrated endovascular aortic repair. The expression of γ-H2AX varied significantly when operators' blood was exposed to the same radiation dose in vitro. This is the first study to measure the acute DNA damage response in patients and operators after fluoroscopically guided aortic procedures and highlights the protective effect of leg shielding. Defining the relationship between this response and cancer risk may better inform safe levels of chronic low-dose radiation exposure and help to tailor individualised radiation protection strategies.