The only radiotherapy facility in Guyana, located at Cancer Institute Guyana (CIG) has a linear accelerator (LINAC), potential to produce photons of 6 Megavolts and 6 electrons energies of 5,7,8,10,12 and 14 MeV. This research aims to evaluate the levels of ionizing radiation retrospectively received by the OEP in the radiotherapy facility at CIG for 5 consecutive years from 2010 to 2014 inclusively and to relate the findings to the national and international dose limits of 20 mSv/year, for both safety and regulatory purposes to avoid and/or reduce biological effects. The Occupationally Exposed Personnel (OEP) are routinely monitored by the quarterly genesis Ultra TD dosimeter authorized by Sierra Radiation Dosimeter Service. Even though the results were well below the National and International dose limit, the results produced a variation of more than 2.1 mSv with a minimum mean annual dose of 0.264 mSv and a maximum mean annual dose of 2.353 mSv. Each OEP dose readings throughout the years was significantly below 5 mSv/year. These results allows the researcher to conclude even though the dose is well below 20 mSv, the need for optimization still applies. Background radiation, cannot be removed completely, but continuous monitoring should be done to help keep allows for radiation dose As Low As Reasonable Achievable (ALARA).

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.