Brazilian regulatory authority contribution to the shielding dimensioning model of radiotherapy rooms proposed by the NCRP 151

Abstract

The National Council on Radiation Protection and Measurements (NCRP) Report No. 151 is an essential document for bunker design commonly applied for radiotherapy treatment rooms. This document is used as a reference by several countries, including Brazil. The objective of this study is to evaluate the shielding dimensioning methodology recommended by NCRP 151, and compare it with the one adopted by the Brazilian regulatory authority. Radiotherapy rooms and respective doors were designed to use linear accelerators operating at 6, 10, 15, and 18 MeV under two different ways: (a) applying exclusively the methodology recommended by the NCRP 151, and (b) taking into consideration the complementary recommendations from the Brazilian authorities. The results suggest that designers in Brazil can count on at least 4 and 11% safety margin for dimensioning primary barriers in controlled and free areas respectively. Also 8% for secondary barriers in controlled areas, 9.7% for secondary barriers adjacent to the primary belt of free areas, and 6.6% for the lead of the doors.

Ferramenta computacional para o cálculo da blindagem de salas de radioterapia de acordo com os critérios de aprovação da autoridade reguladora brasileira

“…O Excel foi utilizado como ferramenta de suporte para criar planilhas de cálculo, controlar informações, testar e comparar os resultados com o RadCAL. (NCRP, 1976;ICRP, 1982ICRP, , 1991IAEA, 2006), e trabalhos Brazilian Journal of Development, Curitiba, v.10, n.2, p. 01-14, 2024 publicados (HASSAN et al, 2018;DI PRINZIO & FACURE, 2014;BRAGA et al, 2020;CHARALAMPIA et al, 2023).…”

“…reproduziu com precisão os resultados apresentados por(BRAGA et al 2020). A Tabela 1 compara os cálculos de blindagem entre o RadCAL e o trabalho supracitado.…”

“…Em relação às áreas não controladas, ambas as normas estão de acordo. O estudo realizado por(BRAGA et al, 2020) considerou espessuras de blindagem para fótons de energia de 6, 10, 15 e 18 MV, individualmente. Entretanto, no RadCAL, todas as energias do concreto recomendadas pela NCRP 151 foram consideradas no cálculo convencional das barreiras primárias e secundárias.…”