Response to Bieko re: Risk of Radiation-Induced Cataracts: Investigation of Radiation Exposure to the Eye Lens During Endourological Procedures

Dear Editor:

We completely agree with the editorial comment. Although the estimated radiation dose during endourologic interventions is far below the biologic activity, we should reduce radiation exposure whenever possible. Critical cumulative lens doses should not be underestimated especially since the latest knowledge in radiation sensitivity of the eye lens. ¹

For that reason, we performed further analyses—besides the presented—to check some tools for reduction of the radiation exposure of the urologist.

In addition to the two mentioned dosimeters (thermoluminescence dosimeter—TLD-100H—and electronic personal dosimeter EPD Mk2 [both: Thermo Fisher Scientific, Waltham, MA]), we used two RaySafe i2 dosimeters (RaySafe, Billdal, Sweden). This RaySafe i2 dosimeter and its related system allows a live real-time observation of personal radiation exposure, which may lead to a better chance of controlling the exposure complying with the ALARA principles. ² As reported, ³ the RaySafe i2 dosimeter has an angular dependence and has a significant measurement inaccuracy for radiation angles of >60°. This correlates with the measurement inaccuracy, which is supplied by the manufacturer (±30% within ±50° and +200%/−100% within ±90°). In our examination, even for taller urologists and a possible short distance to the radiation source, we did not see a significant inaccuracy for measuring the eye lens dose. An analysis of the dose values at the lead apron collar of the urologists showed that the TLD and the RaySafe i2 did not exceed the measured dose of the calibrated electronic dosimeter EPD Mk2. The respective linear regression resulted in a slope of <1. The measured dose deviated by −28% (R ² = 0.98) for the TLD and by −4% (R ² = 0.98) for the RaySafe i2, respectively. If this system can reduce the radiation exposure for urologists during endourologic procedures, application of the live monitor inside the operating room has to be investigated.

X-ray protective glasses or visors are not commonly used. ⁴ For a small series of eight interventions, one urologist used an X-ray protective lead glass shield. In contrast to the mean eye dose value in our cohort per intervention of 20 μSv (mean dose area product: 233 μGym ² ), this urologist reduced his mean value to 5 μSv per intervention (mean dose area product: 350 μGym ² ) using an X-ray protective lead glass shield: a total reduction of 75%. Therefore, in our opinion, an X-ray protective lead glass shield is a cheaper and easier-to-use tool for a significant radiation exposure reduction than X-ray protective glasses. Moreover, protective lead glass shields reduce the scatter radiation exposition of the whole neck and head region and not merely the exposition to the eye. Furthermore, considering hospitals with many different surgeons and different needs of vision correction, a small number of glasses are not sufficient. In our urologist cohort, almost half of the urologists need vision correction.

But in essence, Beiko is completely right: it is time for the urologist to take care of himself/herself.