A new proposal on the operational quantity Hp(3): Monte Carlo and experimental results

The European Union is funding the ORAMED Contract (Optimization of RAdiation protection for MEDical staff) project that aims at developing methodologies for better assessing and reducing exposures to medical staff for procedures resulting in potentially large doses or complex radiation fields, such as interventional radiology, nuclear medicine and new developments. One of the ORAMED Working Tasks is addressed to the discussion and implementation in the radiation protection practice of the eye lens equivalent dose. The aim of this task group is to develop a personal dosemeter characterized in term of H-p(3). Until now H-p(3) conversion coefficients were not reported in the official recommendations and the available data were calculated for a 30 x 30 x 15 cm(3) slab phantom that is far away to represent the head. A reduced slab phantom, for both calculating the quantities and type testing personal dosemeter in terms of the operational quantity, was previously proposed by ENEA Bologna team. The study demonstrated that a reduced slab phantom is better representative of a real situation, but the angular dependence of H-p(3,alpha ) due to the edges of the slab reduces its applicability. Therefore a better-suited phantom is proposed here. The dosimetric assessment in terms of this quantity is seldom performed in the various workplaces (e.g. hospitals) and therefore a question rises about its usefulness and practical implementation. The present work tries to introduce new elements in the discussion on the quantity H-p(3) and to propose a more suitable theoretical cylindrical phantom (and a corresponding experimental one for the calibration procedures) to better approximate the head in which the eyes are placed. Published by Elsevier Ltd.