A new 3D printed applicator with radioactive gel for conformal brachytherapy of superficial skin tumors

Abstract

Surface brachytherapy is an effective method in the treatment of skin cancer. Current skin brachytherapy techniques are based on the placement of a source of gamma or X-ray photons in a close distance from the skin to irradiate the lesion. Due to the nature of photons, radiation dose in these methods may affect healthy tissue as well as sensitive structures around the target. In order to minimize unwarranted and incidental exposure, we propose a new skin brachytherapy applicator based upon beta particles which have penetration ranges of a few millimeters in tissue. The proposed concept is radioactive gel housed within a pre-designed tumor-specific applicator matching the topology of the skin lesion. The particles mixed with the gel showed a uniform distribution pattern, which is an essential prerequisite in having a uniform dose profile on the skin surface. Based on the dose calculation data from the proposed concept, the dose delivered to the depth of 4500 µm in skin tissue is 10% of the dose delivered to the surface of the tumor, making it suitable is treating thin skin tumors especially when located on top of the bone. Through the innovative combination of radioactive gel and tumor-specific applicator, the radiation entering the skin surface can be personalized while minimizing the adverse effects of undesired exposure to the surrounding healthy tissue.