Evaluation of dose uniformity ratios in a proposed multi-product gamma irradiator facility using Monte Carlo method

Source-product irradiation geometry of radiation processing facilities is required to be designed to deliver prescribed dose to the product within the acceptable 'dose uniformity ratio' so as to meet the national standards. This paper presents the simulation of irradiation geometries for a proposed multi-product gamma irradiation facility using Monte Carlo method. Three source-product geometries are analysed for product densities. 0.15 g/cm3, 0.4 g/cm3 and 0.6 g/cm3. The dose uniformity ratios are evaluated by computing dose distribution profile in the product box in each case to choose optimum irradiation geometry to achieve the acceptable dose uniformity ratio. The computations were also made by point kernel method for comparison purposes and the dose rate values agree to within 3-15% when compared to Monte Carlo method. The Monte Carlo-based values of dose uniformity ratios are higher than the acceptable values for geometry-1 whereas the same for the other two irradiation geometries are acceptable. The dose uniformity ratios are presented in each case. (author)