Hp(3) vs TLD-100 for eye lens dosimetry in interventional radiology procedures: a preliminary study

Abstract

Following the 2013/59/EURATOM Directive, the Italian 101/2020 Decree Law lowered the annual limit on the equivalent dose to eye lens from 150 to 20 mSv for exposed workers, in order to limit the risk of radiation-induced cataract. Such a drastic reduction makes it very important to perform accurate dose monitoring for medical staff that works with ionizing radiation as interventional radiologists and cardiologists. The standard for occupational eye lens dosimetry consists into Hp(3) calibrated dosimeters placed on physicians glasses, next to the eyes. However, this dosimetry system suffers calibration issues, and therefore, the dose is usually extrapolated from extremity or whole body measurements, leading to low accuracy. Chips of thermoluminescent dosimeters TLD-100 and dedicated Hp(3) calibrated dosimeters were placed over a plexiglas (PMMA) phantom to measure the Entrance Surface Air Kerma (Ke) and the eye lens equivalent dose (H) to physician, respectively, during simulated interventional radiology procedures. Values were all below the regulatory limit. Our results show that TLD-100’s response seems to be correlated with Hp(3) according to the relationship Ke = F × H, with an average factor F = 3.9 mGy/mSv, opening the possibility of using both dosimeters for accurate radiation protection of exposed workers.