Scientia Africana

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Evaluation of effective dose and excess lifetime cancer risk from indoor and outdoor gamma dose rate of university of Port Harcourt Teaching Hospital, Rivers State

C.P. Ononugbo, G.O. Avwiri


An in-situ measurement of indoor and outdoor radiation dose rate at the University of Port Harcourt Teaching hospital was done using well calibrated radiation meter (Radalert-100). The minimum and maximum indoor gamma dose rate were found to be 121.8 ±4.02 nGyh-1 and 200.1±5.06 nGyh-1 respectively while the minimum and maximum outdoor gamma dose rates were 87.0 ±2.07nGyh-1 and 200.1± 4.07nGyh-1. The study also revealed that the average annual effective dose rate is 0.31±0.002 mSvy-1 and 0.92 ±0.02 mSvy-1for outdoor and indoor measurements respectively. In addition, the excess lifetime cancer risk (ELCR) calculated for indoor exposure ranges from 1.68 × 10-3 to 3.22 × 10-3 with an average value of 0.83 × 10-3. For outdoor exposure ELCR varies from 0.46 × 10-3 to 1.09 × 10-3 with a mean value of 2.289 × 10-3. The average values for indoor and outdoor gamma doses were found to be greater than the world population weighted average for indoor gamma dose rate of 89 nGyh-1. The result shows that ELCR for both indoor and outdoor exposure were higher than the world acceptable value of 0.29 × 10-3,though the annual effective dose levels in all of the locations (indoor and outdoor) were below the 1mSvy-1 maximum permissible limit for the public set by International Commission on Radiological protection (ICRP). Therefore, the management of University of Port Harcourt teaching hospital should undertake a routine maintenance of diagnostic equipment(x-ray machines, CT scanners) may have to avoid leakage which may have contributed to the enhancement of background radiation of the hospital.

Keywords: Dose rate, absorbed dose, background radiation, effective dose, ELCR, radiological

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