Impact of radiotherapy facility on indoor background radiation exposure at the University College Hospital, Ibadan

Abstract

Background: The impact of high energy radiotherapy machine, used for cancer management at the University College Hospital, Ibadan, on indoor background radiation exposure of humans (staff, patients and their relatives) has been assessed. Methods: Gamma radiation detectors were used to measure background radiation exposure rate at designated areas within the Department of Radiation Oncology over a period of three years (2014 - 2016). Results: The mean indoor background radiation exposure rate (µR/hr) measured at these areas ranged from 0.139±0.053 to 0.157±0.061 while the corresponding mean absorbed dose rate (nGy/hr) ranged from 1.210±0.459 to 1.367±0.531. The effective dose, which is the radiation quantity defined by the International Commission on Radiation Protection (ICRP) to specify annual dose limit for both radiation workers (20 mSv averaged over 5 years) and the general public (1 mSv), was determined from the background radiation absorbed dose rate per annum and compared with the ICRP recommended radiation dose limit for general public. The mean annual effective dose (mSv) arising from background radiation obtained within the department of Radiation Oncology ranged from 0.019 to 0.021, which is about 2% of the recommended dose limit (1 mSv) for general public. Conclusion: This result showed that the presence of high energy radiotherapy machine located in this department has no significant effect on the indoor background radiation exposure of people who work in or visit the department. Further study is aimed at measuring both indoor and outdoor background radiation exposure at other departments in the hospital and estimate their health impact on humans.