Revista de Métodos de Diagnóstico Médico
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Abstrato

An Evaluation of the Effectiveness of the Structural Radiation Shielding Barriers of a Radiation Therapy Facility: Cancer Institute of Guyana

Seodat P, Surujpaul PP, Errada D

This project thoroughly investigates the integrity of the structural radiation shielding barriers of the radiation therapy facility of Cancer Institute of Guyana which houses a Linear Accelerator (LINAC) of 6 MV. The LINAC comprises a retractable beam stopper which renders all barriers of the bunker as secondary. However, the barriers that receive the primary incidence of the beam at the gantry angles 900 and 2700, Walls A and B, have been annotated as primary. In addition, for the other barriers, a phantom was used in making measurements for scatter. The bunker at Cancer Institute has been in existence since 2006. Therefore, the primary aim of this study is to validate the effectiveness of the structural radiation barriers of the radiation therapy facility through measurements and computations of the Instantaneous, Time Averaged and Weekly Dose Rates of the barriers and calculations of the attenuation coefficients using the Tenth value layer of the existing shielding material, concrete. The results gathered serve as a basis for comparative analysis to the Institute’s Commissioning Report and the International Standards. The Instantaneous measurements were recorded using the Fluke Biomedical Ionization Chamber.

The results of the project annotate that the radiation shielding barriers at Cancer Institute of Guyana are very effective. The instantaneous dose rates recorded by the ionization chamber of the existing barriers were significantly lower than those calculated. The time averaged and weekly dose rates were very low as well. Scattered radiation measured conformed with the international standard of being less than 0.1% of the primary beam. However, calculations for barrier thicknesses required were higher than the existing barrier thicknesses. This was as a result of the field size parameter of the LINAC being utilized at its maximum. Nevertheless, these verifications of the effectiveness of the radiation shielding barriers were in conformity to the stipulated standards and well below calculated outcomes.