Depth Dose Profile and Exposure Time Calculation in an 60Co Irradiation Processing Facility: MCNP and GEANT4 Calculation

The present research is proposing a mathematical method to calculate the dose absorbed by a moving object in a non-uniform radiation field. In such conditions, the dose is the function of time and position of the object relative to the radiation source. In this regard, a 60 Co irradiation processing facility has been investigated in which, the non-uniform planar source of gamma-rays, irradiates the boxes moving which move around the source. In irradiation facilities, addition to the strength of 60 Co source, the speed of boxes is in great importance in obtaining the desired total dose to the boxes, however in most cases, the speed has been determined traditionally and by try-and-error method after the construction and installation of the radiation source. In this research, the speed of boxes (conveyor’s speed) was determined so that, the desired dose has been delivered to each box. The dose profile inside of the boxes has been calculated based on the different positions from the rack. The presented calculations aim to optimize the detailed design of the mentioned facility and for the more efficient performance because, it helps to make the faster radiation processing in a smaller place. The calculations have been conducted using MCNPX.2.7 and Geant4.10.5 Monte Carlo tools in order to obtain most reliable results. Health Phys. 000(0):000-000; 2025