Considering the continuous advance in technology, the interventional procedures become more complex, and some require extensive use of x-ray imaging and raise new issues of occupational protection. The International Commission on Radiation Protection (ICRP) Publication 139, on occupational radiological protection in interventional procedures, provides advice on specific issues, such as assessment of effective dose from dosimeter readings when an apron is worn, estimation of exposure of the lens of the eye (with and without protective eyewear), extremity monitoring, among others [1]. The use of electronic personal dosimeters is becoming more widespread in hospitals and generally found to be beneficial due to instant readings. These dosimeters can provide both personal dose equivalent rate Ḣp(10) (dose rate) and personal dose equivalent Hp(10) (dose) of continuous and pulsed X-ray and gamma radiation, and thus, can be useful for optimization purposes. For individual monitoring, electronic dosimeters should, for instance, have an adequate energy range, sensitivity, linearity and precision; they should be reliable; and sufficient quality control measures and periodic calibration procedures should be in place [2].

In this study, three electronic personal dosimeters of Polimaster® model PM1630 were chosen for characterization in terms of Hp(10), based on the recommendations of the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). The dosimeters were irradiated in X-ray and gamma radiation beams, according to reference conditions of ISO 4037-1:2020 [3] and BS EN 61526:2013 [4]. The gamma irradiator (IRGA-01) model OB85/1 (with 137Cs source of 740 GBq) and X-ray irradiator (EQRX-02) model GE Isovolt 160 are both located in the Calibration and Dosimetry Laboratory (LCD) at the Nuclear Technology Development Center (CDTN). In gamma radiation beam, the dosimeter was positioned on the surface and in the center of the ISO standard water phantom, within the radiation field, with its longitudinal axis in the vertical direction and perpendicular to the central axis of the radiation beam, with the front face facing the beam and its geometric center at a distance of 1.5 m from the radiation source. For electronic equilibrium, a 3 mm thick PMMA plate was used positioned on the surface of the dosimeter. In X-ray beam irradiations, with normal incidence (0°), the dosimeter was positioned at 1.5 m from the focal point of the X-ray tube, without the 3 mm thick PMMA.

According to IEC, all the relative response values due to photon radiation energy and angle of incidence shall be within the interval from 0,71 (-29%) to 1,67 (+67%) for all energies above or equal to 50 keV (energy range covering interventional procedures). In this case, the Hp(10) measurements of the dosimeters are in the range of +35%, considered adequate. In gamma radiation beam, all PM1630 dosimeters cover the effective range for the measurement quantity Hp(10), within 5% error to the corresponding values of 5 µSv, 50 µSv, 500 µSv and 5 mSv.

This work was supported by the Brazilian National Council for Scientific and Technological Development (CNPq, Project INCT/INAIS – 406303/2022-3, CNPq Process 308368/2022-3, and CNPq Project 422164/2023-2 – PCI-DB), and the State Agency for Research and Development of Minas Gerais (FAPEMIG).