THE DOSE DISTRIBUTION SURROUNDING IR-192 AND CS-137 SEED SOURCES

Dose distributions in water have been measured using LiF thermoluminescent dosimeters for Ir-192 seed sources with stainless steel and with platinum encapsulation to determine the effect of differing encapsulation. The dose distribution has also been measured for a Cs-137 seed source. In addition, dose distributions surrounding these sources have been calculated using the EGS4 Monte Carlo code and have been compared to the measured data. The two methods are in good agreement for all three sources. Tables are given which describe the dose distribution surrounding each source as a function of distance and angle. In addition, specific dose constants have been determined from results of Monte Carlo simulation. This work has confirmed the utility of the EGS4 Monte Carlo code in modelling Ir-192 and Cs-137 seed sources to obtain brachytherapy dose distributions.