Photon doses at the entrance of 60Co and low-energy medical accelerator rooms under unusual irradiation conditions

Abstract

In this paper, the general-purpose Monte Carlo code MCNP5 was used to study the dose variance due to the position of medical linear accelerators, under unusual conditions, for shielding design of radiotherapy facilities. It was found that the computational methods generally used to estimate the scattered photon doses at the entrance of radiotherapy unit vaults provide conservative results when compared with the MCNP results, considering the standard condition. On the other hand, for the situations where the axis of gantry rotation is redirected at, for example, 45 degrees with respect to the walls of the room, the photon doses at the entrance can reach values up to seven times higher than those obtained under the standard condition, depending on the energy of the primary beam.

An analysis of the regulatory program of quality audits in radiotherapy in Brazil from 1995 to 2007

“…In many cases the facilities were subjected to nonauthorized project changes, or the person responsible for the facility decided to utilize a higher activity source not appropriate to the existing approved irradiator bunker shielding . ( 21 ) Another possible reason is a unit was positioned at an unusual configuration (for instance, forming angles about 45° with the bunker walls), a situation that can generate higher dose rates in the neighborhood of the treatment room (22) …”

Investigation of Scattered Radiation Dose at the Door of a Radiotherapy Vault When the Maze Intersects the Primary Beam

“…A variant of this problem was previously investigated by Facure et al where they studied the effects of photon dose-equivalent at the vault door from "unusual" gantry orientations [2]. They found that an increase by up to a factor of 7 for photon dose-equivalent could be achieved by orienting the gantry at 45˚ to the maze normal, but that photon dose-equivalent was reduced by approximately a factor of 2 by pointing the gantry directly towards the maze.…”

Análise comparativa dos efeitos da atividade física através da mensuração de citocimas pró-inflamatórias em pulmões irradiados de ratos

“…Desde o advento da teleterapia, tanto as técnicas de tratamento quanto de equipamentos melhoram significativamente e protocolos foram estabelecidos tanto para os operadores, quanto para o público alvo devido à exposição à radiação. Muitas publicações têm sido avaliadas ao longo dos anos para elucidar os efeitos destas mudanças nas técnicas protetoras (FACURE et al, 2010).…”

“…Exercício de resistência associado à lesão muscular induz a resposta inflamatórias maior (NIEMAN, 2000). A utilização dos métodos de imunohistoquímica e bioquímica para a avaliação das citocinas pró-inflamatórias pulmonares tem sido usada há muito com sucesso (ESCOTTE et al, 2003;RABBANI et al, 2005;LEE et al, 2006b;FENG et al, 2008;KIM et al, 2008;ZHAO et al, 2008;CHEN et al, 2009;KIM et al, 2009;CHEN et al, 2010;MOON et al, 2010). Em alguns outros estudos, a utilização do sangue periférico para a avaliação da expressão de tais citocinas não se mostrou eficaz, como, por exemplo, o estudo realizado por MORITA et al…”