ASSESSMENT OF RADIATION DOSE RATE LEVELS AND RADIATION RISK AT THE COBALT -60 UNIT, KOMFO ANOKYE RADIOTHERAPY CENTER, GHANA.

Abstract

Purpose: A study was conducted to estimate the Annual Effective Dose Equivalent (AEDE) and Excess Lifetime Cancer Risk (ELCR) caused by the presence of an artificial cobalt-60 radioactive source producing ionizing radiation levels within the radiotherapy facility at Komfo Anokye Teaching Hospital (KATH) in Ghana. This study validated the safety of cobalt-60 radioactive sources, as well as the notion of calculating the Annual Effective Dose Equivalent (AEDE) and Excess Lifetime Cancer Risk (ELCR), which contributed to reducing occupational and public exposures inside the facility.
 Methodology: The investigation was carried out with the use of a portable OD-01 Ionization Chamber Survey Meter. The absorbed dose rate (ADR) in air was changed between 5 m and 40 m, with measurements taken inside and around the cobalt 60 bunker, as well as at sixteen other sites within the radiation facility.
 Findings: From 5 m to 40 m surrounding the Cobalt-60 source, the estimated Absorbed Dose Rate in air inside the cobalt-60 bunker ranged from 0.299 0.001 to 0.977 0.005 Sv/h, with an average of 0.498 0.005 Sv/h. The estimated Annual effective dose equivalent varied from 1.100 mSv/yr to 3.595 mSv/yr around the cobalt-60 source inside the Co-60 bunker. Radiation exposure levels ranged from 0.268 0.008 Sv/h to 0.678 0.005 Sv/h, with an average of 0.440 0.004 Sv/h observed around the fifteen sites chosen. Excess Lifetime Cancer has values ranging from 3.85 10-3 to 12.58 10-3 and 3.45 10-3 to 8.73 10-3. Risks were evaluated for the cobalt and the sixteen places inside the plant. The absorbed dose values at 5 m, 10 m, and 15 m inside the Co-60 bunker and the location Co-60 bunker as part of the facility exceeded the ICRP-recommended limit of 0.57. The AEDE and ELCR levels were within the ICRP's acceptable limits. The AEDE and ELCR statistics acquired indicate that the Cobalt-60 unit and its surroundings are radiation safe, although the likelihood of employees contracting cancer from the absorbed dose and background ionizing radiation is significant over a lifetime.
 Recommendation: However, it is recommended that absorbed dose level monitoring and evaluation of the Radiation Therapy Technologist (RTT) and other workers surrounding the unit be monitored on a regular basis. It is also recommended that Occupational Staff, such as RTTs, spend as little time as possible in the bunker