Development and validation of a methodology for dose calculation in electron beam irradiation of complex-shaped foods

Obtaining a uniform dose in inherently irregularly shaped foods, such as an apple, is very difficult, and development of accurate dose calculation methodologies is needed. The specific objectives of this study were: (1) to obtain detailed, high resolution dose maps using CT scanning and Monte Carlo simulation techniques, and (2) to determine the accuracy of the dose calculation methodology by irradiating food phantoms with a Van de Graaff accelerator. Phantom apples were made using a mixture of chloroform, methyl yellow dye, and paraffin wax. Absorbed dose was determining by measuring the corresponding color changes of the dye in irradiated phantoms. 3-D dose distributions in the phantom and an actual apple were calculated using Monte Carlo methods. Both the measured and calculated dose distribution values in the phantom were very similar. Evaluation of food positioning strategies in front of the e-beam source demonstrated that tilting and axial rotation ensure uniform dose distribution of the entire surface of the phantom, even reaching the critical regions of the apple stem and calyx ends.