A common protocol is also used for the retrospective assessment of the cumulative eye lens dose in each country. Two independent approaches have been developed and will be used:
- Assessment of eye lens dose from published eye lens dose data
- Assessment of eye lens dose from routinely measured whole body doses
Both approaches are complementary and while the first is a retrospective estimation of the dose to the eye itself based on self-reported occupational history, the second has to convert whole body dose to eye lens dose, having the advantage of being highly specific to the cardiologist and is derived prospectively over time.
1. Assessment of eye lens dose from published eye lens doses
An extensive database of eye lens dose values among interventional cardiologists is available from the European ORAMED project [Vanhavere, 2011], but also from many other published studies on eye lens dosimetry.
Based on the information collected with the occupational questionnaire, typical eye lens dose values will be determined for each type of procedure covering each working period, reported by the interventional cardiologist. This will allow estimation of exposure based on work history and it will be corrected for changes in procedures and X-ray equipment over the years.
2. Assessment of eye lens dose from whole body dose
An extensive measurement campaign was performed in a previous European study ELDO (approved within the DoReMi external research call) to estimate the conversion factor from whole body dose (measured above the protective lead apron) to eye lens dose and its associated uncertainty [Farah, 2013].
The impact of the use of protective equipment (lead glasses, lead screens) on the conversion factor from whole body dose to eye lens dose has also been established within ELDO from an extensive Monte Carlo simulation campaign [Koukorava, 2014].
Information for each working period on the position of the whole body dosemeter and the use of protective equipment is collected through the occupational questionnaire.