A computational tool for evaluating the at risk staff absorbed dose in nuclear medicine treatments

M. VALENTE; G. TIRAO

Rio de Janerio, Brasil

Conferencia; 8º LOWRAD International Conference; 2009

Comisión Nacional de Energía Nuclear Brasilera

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:IT; mso-fareast-language:IT;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Objectives: The main objective is to develop a dedicated program, based on Monte Carlo simulations techniques, in order to perform absorbed dose calculations for the evaluation of exposure risks during nuclear medicine practices.   Methods: A dedicated Monte Carlo program has been adapted from the main code PENELOPE in order to perform suitable absorbed dose computation due to radioisotope exposure. The develop program allows to define a desired irradiation set up, which involves geometry and materials. Dedicated routines are incorporated to 3D dose distribution calculation. In addition, adapted software (MatLab supported) allows to assess a suitable visualization of 2D “hot-points”. Furthermore, once the program is already validated, it becomes possible to introduce attenuators for radiation protection purposes. The effectiveness performances of different shieldings are investigated as a function of different parameters, like relative distance and radioisotope properties.      Results: The first step regarding the preliminary validation of the developed program establishes its feasibility and reliability. After that, dedicated simulations are performed in order to evaluate the dose distribution according to different relative positions of exposed person to the patient. Different radioisotopes, which emission spectra were already suitably characterized, are considered as radiation sources. The dedicated visualization program provides a comfortable, easy and user-friendly graphical interpretation of obtained dose distribution, which emphasize relative higher risk zones. The protection insertions are successfully taken into account, which show the expected relative radiation risk reduction.   Conclusions: The main goal of developing an original subroutine for the calculation of absorbed dose during nuclear medicine treatments is successfully achieved. Actually, this program, based on the evaluation of absorbed doses, could be considered as a helpful tool in order to establish optimal daily radiological protection criteria, even according the actual radioisotope source.