Radiation dose profile in 125I brachytherapy: an 8-year review

The use of episcleral plaques containing radioactive 125I seeds for brachytherapy treatment of selected retinoblastoma cases of patients is being done in Riyadh, Saudi Arabia since 1994. There are about three to four patients per year. A total of 31 patients were treated with a tumour dose in the range of 40-60 Gy using 8 seeds of 125I each from 1994 to 2002. This study determines the trend of occupational doses received by surgeons, anaesthesiologists and nurses and the dose rate profile around the eyes. Only 3% of the 275 persons monitored for Hp(10) have measurable doses with a weighted average of 4 microSv and 7% of the 175 persons monitored for Hp(0.07) have measurable doses with a weighted average of 0.3 mSv. The dose rate is maximum (110 microSv h(-1)) at the point of contact with the eye plaque and reduces to approximately 40% on the side of the other eye.