Assessment of pre-operational radiological conditions at the Linac Centre of the Lagos University Teaching Hospital, Nigeria.

Background: The Lagos University Teaching Hospital, Nigeria has acquired a 6 - 15 MeV ELEKTA linear accelerator for clinical teletherapy. The 15 MeV is a sufficient energy to activate photonuclear interactions of the type (h(nu), n) and (h(nu), e), in some materials found within the locality, thereby enhancing the background radiation exposure levels in the environments.

Objective: The objective of this study is to conduct a pre-operational assessment of the radiological conditions of the new LINAC Centre and its environments which is required for future uses in the assessment of the environmental impacts due to the applications of the facility. The results of this study are to provide a baseline data needed for such assessments and the impact of eventual LINAC accidents.

Methods: Radiation exposure levels due to natural background radioactivity in the controlled and supervised areas and offices in the LINAC localities have been measured. The environmental radiation survey around the Centre was conducted according to the requirements prescribed by the ICRP, IAEA Basic Safety Standards etc. The specific radioactivity contents of 100 building, furna and flora material samples have been determined using a Gamma Well Scintillation Counter.

Results: The mean exposure rates all over the LINAC Centre varied from 2.0 muSvh(-1) to 3.3 muSvh(-1). In the controlled areas, the mean value was 2.4 muSvh(-1) and it was 2.7 muSvh in the supervised areas, while in the adjacent offices, it was 2.5 muSvh(-1). The means of the measured specific activities in the cement concrete, soil, plant and grass samples were 42.7299 Bqkg(-1), 39.9592 Bqkg(-1), 23.9010 Bqkg(-1) and 20.8940 Bqkg(-1) respectively.

Conclusion: A database for the assessment of the environmental impacts of the clinical LINAC and the impacts of its eventual accidents has been generated for future periodic uses.