Dose optimization of high dose rate brachytherapy for skin cancer treatment using Harrison-Anderson-Mick applicator

摘要

Brachytherapy is one of the most common forms of localized cancer treatment, it has played an important role in the management of different cancer types. In the present study, we developed a high dose rate brachytherapy treatment for superficial skin. For this purpose, we established an algorithm to deliver a uniform prescribed dose of 6 Gy to a flat surface using PHITS Monte Carlo code. In this treatment, the Cobalt-60 source is placed on the affected area of the skin through Harrison-Anderson-Mick applicator which contains five embedded catheters, in each, five dwell positions were activated. The dwell times, corresponding to the source stops, were optimized using the Tikhonov regularization and the L-curve methods in order to achieve the clinical goal of brachytherapy treatment, which is delivering 6 Gy uniformly over the affected area during the irradiation while keeping a constant distance under the skin. Therefore, the uniformity of the dose was observed in the 2D isodose curves and 3D isodose surfaces at the target distances from the plane of the active positions within the applicator and the prescribed dose was delivered to the affected area uniformly.