96. Evaluation of the equivalent dose to the crystalline lens by dose equivalent Hp(3)

Abstract

Purpose Individual dosimetry provides the tools for measuring doses from ionizing radiation of exposed workers. Recent scientific and epidemiological evidence highlights the need for adequate measures to protect the eye with particular regard to the crystalline lens [1] . The ICRP 103 proposes a depth of d = 3 mm for monitoring the crystalline dose (Hp(3)), stating that also the Hp(0.07) with calibration on slab can be used [2] . In our Dosimetry Service the operating quantity Hp (3) has been introduced and compared with Hp(0.07). Methods A SLAB phantom calibration was performed at a LAT center in terms of Hp (3). The type of dosimeter is ext-rad TLD-100 of Lithium Fluoride LiF:Mg,Ti. Dosimeters were sent to be irradiated in Hp(3) with narrow photon beam at various energies. The irradiation parameters are in the Table. Hp(0.07) and Hp(3) were measured for 26 workers. The monthly measures collected relate to the semester January-June 2017. Results The Figure shows for each operator the sum of the Hp(0.07) (red) and the Hp(3) (blue). The sum of the Hp(3) is greater than the sum of the Hp(0.07) as well as every single monthly value. Percentage differences were calculated between all the values of the Hp(0.07) and the Hp(3) and the average value is 10% ± 3%. Conclusions In the same conditions of irradiation Hp(3) is greater than Hp(0.07). Expected result as to a depth of d = 0.07 mm the absorbed dose is lower than that at a depth of 3 = mm at the energies considered. Download : Download high-res image (65KB) Download : Download full-size image Download : Download high-res image (93KB) Download : Download full-size image