Risk Assessment of Occupational Radiation Dose at The Teletherapy Facility of the Korle-Bu Teaching Hospital Ghana

ABSTRACT

 The National centre for Radiotherapy and Nuclear Medicine at the Korle-bu Teaching Hospital in Ghana uses a Theratron Equinox 100 Cobalt-60 teletherapy machine that was commissioned in 2014 with a source activity of 370.4TBq. The prime objective of this research was to estimate the risk and probability of cancer induction to workers and also to evaluate the level of radiation safety at the facility. Data was collected by means of TLDs and personal dose records available between the periods February 2010 and April 2016. The results from 2010-2016 were used to compute the mean annual dose, mean annual collective dose as well as risk assessments using the ICRP 1990 and 2007 recommendations. Ambient dose rate measurements were also done using a Thermo electron survey meter. The Results showed that mean effective dose recorded from TLDs used in this research ranged from 0.08mSv-0.36mSv whiles dose records from 2010-2016 showed mean annual effective doses ranged between 0.23mSv-0.65mSv.Mean annual collective dose was 0.09 manSv. Annual cancer risk estimates also showed that workers probability of developing cancers had a mean value of 2.37 x 10-2±7.75 x 10-3 whiles risk of passing hereditary traits to offspring born after exposure showed a mean value 3.96 x 10-3± 1.29 x 10-3 according to the ICRP 1990 recommendations and ICRP 2007 showed that possibility of cancer induction to workers showed a mean value of 2.03 x 10-2±1.61 x 10-3.

Mean annual dose rates did not exceed 14.8mSv/a,5mSv/a and 0.74mSv/a for the treatment room, control console room and the controlled area respectively. This shows that workers at the facility 2 are not likely to exceed the recommended dose limit within a year while working at the facility. Ambient dose rates did not exceed 7.39µSv/hr, 2.80µSv/hr and 0.37µSv/hr for the treatment room, control console room and the controlled area respectively. These values obtained are below the recommended limit of 20µSv/hr.