The impact of x-ray tube configuration on the eye lens and extremity doses received by cardiologists in electrophysiology room

Ionising radiation and lens opacities in interventional physicians: results of a German pilot study

We assessed the feasibility of an epidemiological study on the risk of radiation-related lens opacities among interventional physicians in Germany. In a regional multi-centre pilot study associated with a European project, we tested the recruitment strategy, a European questionnaire on work history for the latter dosimetry calculation and the endpoint assessment. 263 interventional physicians and 129 non-exposed colleagues were invited. Questionnaires assessed eligibility criteria, risk factors for cataract, and work history relating to occupational exposure to ionising radiation, including details on type and amount of procedures performed, radiation sources, and use of protective equipment. Eye examinations included regular inspection by an ophthalmologist, digital slit lamp images graded according to the lens opacities classification system, and Scheimpflug camera measurements. 46 interventional (17.5%) and 30 non-exposed physicians (23.3%) agreed to participate, of which 42 and 19, respectively, met the inclusion criteria. Table shields and ceiling suspended shields were used as protective equipment by 85% and 78% of the interventional cardiologists, respectively. However, 68% of them never used lead glasses. More, although minor, opacifications were diagnosed among the 17 interventional cardiologists participating in the eye examinations than among the 18 non-exposed (59% versus 28%), mainly nuclear cataracts in interventional cardiologists and cortical cataracts in the non-exposed. Opacification scores calculated from Scheimpflug measurements were higher among the interventional cardiologists, especially in the left eye (56% versus 28%). Challenges of the approach studied include the dissuading time investment related to pupil dilatation for the eye examinations, the reliance on a retrospective work history questionnaire to gather exposure-relevant information for dose reconstructions and its length, resulting in a low participation rate. Dosimetry data are bound to get better when the prospective lens dose monitoring as foreseen by 2013 European Directives is implemented and doses are recorded.

ON-FIELD EVALUATION OF OPERATOR LENS PROTECTIVE DEVICES IN INTERVENTIONAL RADIOLOGY

The recent publication of the Euratom Directive 2013/59, adopting the reduction of eye lens dose limits from 150 to 20 mSv y^-1, calls for the development of new tools and methodologies for evaluating the eye lens dose absorbed by the medical staff involved in interventional radiology practices. Moreover, the effectiveness of the protective devices, like leaded glasses, which can be employed for radiation protection purposes, must be tested under typical exposure scenarios. In this work, eye lens dose measurements were carried out on an anthropomorphic phantom simulating a physician bound to perform standard interventional neuroradiology angiographic procedures. The correlation between eye lens doses, in terms of Hp(0.07), and the equivalent dose [again in terms of Hp(0.07)] monthly measured with thermoluminescent dosemeters placed above the lead apron at the chest level was studied, in the presence and in the absence of different types of leaded glasses.

EYE LENS DOSIMETRY FOR FLUOROSCOPICALLY GUIDED CLINICAL PROCEDURES: PRACTICAL APPROACHES TO PROTECTION AND DOSE MONITORING

Doses to the eye lenses of clinicians undertaking fluoroscopically guided procedures can exceed the dose annual limit of 20 mSv, so optimisation of radiation protection is essential. Ceiling-suspended shields and disposable radiation absorbing pads can reduce eye dose by factors of 2-7. Lead glasses that shield against exposures from the side can lower doses by 2.5-4.5 times. Training in effective use of protective devices is an essential element in achieving good protection and acceptable eye doses. Effective methods for dose monitoring are required to identify protection issues. Dosemeters worn adjacent to the eye provide the better option for interventional clinicians, but an unprotected dosemeter worn at the neck will give an indication of eye dose that is adequate for most interventional staff. Potential requirements for protective devices and dose monitoring can be determined from risk assessments using generic values for dose linked to examination workload.

The effectiveness of lead glasses in reducing the doses to eye lenses during cardiac implantation procedures performed using x-ray tubes above the patient table

The dose reduction factors (DRF) for different types of lead glasses and C-arm units with x-ray tubes placed above the patient table were calculated from the results of measurements by loose thermoluminescent dosimeters (TLDs) and EYE-D dosimeters using a Rando phantom. The DRF values were analysed for different positions of routine dosimeters worn outside lead eyewear and confronted with DRFs calculated as the ratio of the dose equivalent to the eye measured with and without the eyewear. Moreover, for eye lens dosimeters designed to be worn behind lead glasses, multiplicative factors for various positions of dosimeter were derived in order to account for the differences between the doses measured on the inner side of the glasses and the dose equivalent to the eye lens. The DRFs calculated for the position of a routine dosimeter worn outside lead glasses on the band near the left eye lens are 5.6 and 5.7 for goggles and metallic glasses, respectively, while the DRFs calculated as the ratio of doses to the eyes measured with and without the eyewear are 10.2 and 9.9, respectively. Therefore, for dosimeters routinely used outside lead eyewear, the DRF calculated for the position of the dosimeter should be used. Otherwise, we can anticipate an almost two-fold underestimation of the doses. When the dosimeter is worn behind lead glasses, up to two-fold differences between the dose equivalent to the eye lens and the dose measured at the inner side of the glasses were observed depending on the dosimeter position.