69. The European epidemiological study (EURALOC) on radiation-induced lens opacities among interventional cardiologists

Purpose Low dose radiation effect on the eye lens has been an area of interest in numerous epidemiological studies. The European epidemiological study EURALOC was conducted between December 2014 and May 2017 with the objective to investigate a possible dose-response relationship by targeting a sufficiently large study population with reasonably high exposure levels, namely interventional cardiologists (ICs). Methods In total 393 subjects have been recruited in the exposed group, they have completed study questionnaires on work history and risk factors for lens opacities and received an ophthalmological examination. As for the control group, 243 subjects have been recruited, completing the same questionnaire on risk factors for lens opacities and ophthalmological examination. Efforts have been made to develop 2 approaches to assess retrospectively the cumulative eye lens doses of the recruited cardiologists. The first approach is based on the individual work history in combination with published eye lens dose data, while the second approach is based on individual routine whole body dosimetry and its conversion to eye lens dose. Innovative approaches have been used for the statistical analysis by using a mixed linear regression and polytomous logistic regression approach, which permit a correct modelling of the lens opacities by taking into account the correlation of the soring outcomes of both eyes in the radio-induced risk estimation as well as dose estimation uncertainties. Results More than 200 dose measurements have been performed in clinical practice to validate both calculation approaches. 1st approach resulted in the most satisfactory with an average ratio between measured and calculated eye lens dose of 0.96 [95%CI: 0.87-1.09] for the left eye and 0.50 [95%CI: 0.44-0.56] for the right eye. The analyses established a significant impact of radiation dose in the occurrence of PSC opacities with a relative risk for ICs of OR = 2.62 (95%CI 1.35–5.08). Conclusion A linear no threshold model provided the better fit of the lens opacities dose-response relationship with an excess relative risk per Gy equal to 1.31 (95% CI 0.13–3.32).