Ahmadu Ibrahim, Beatrice Humphrey Bonki and Umaru Musa
Background: Occupational exposure to ionizing radiation in radiotherapy staff is continuously monitored to ensure compliance with regulatory limits and the ALARA (As Low As Reasonably Achievable) principle. The linear-no-threshold (LNT) model is widely used to estimate lifetime attributable cancer risk (LAR) from low-dose radiation exposure.
Objective: To estimate lifetime attributable cancer risk based on the LNT model for radiotherapy staff at UDUTH using 2015 personal dosimetry data.
Methods: A retrospective review of 2015 personal dosimeter records for all radiotherapy personnel at UDUTH was conducted. Annual effective doses (mSv) were collated and converted to Sieverts. Cancer risk estimates per worker were calculated using ICRP nominal risk coefficients and BEIR VII age- and sex-dependent LAR models. Cumulative departmental risk and uncertainties were also evaluated.
Results: Using an illustrative mean annual effective dose of 1.415mSv, individual LAR estimates ranged from approximately 0.0594 to 0.1018 using ICRP and for BEIR VII model ranged from 0.108 to 0.185. Departmental aggregate lifetime excess cancer risk from one year’s exposure remains very low.
Conclusions: The estimated lifetime cancer risks for UDUTH radiotherapy staff from 2015 occupational exposures are low but reinforce the necessity for continued dose monitoring and adherence to ALARA optimization