A plesiotherapy technique for the post-operative treatment of skin cancer using Ir192 microSelectron

We describe a technique of postoperative irradiation of skin cancer using plesiotherapy with Ir192 high dose rate microSelectron afterloading system (Nucletron, Veenendaal, Netherlands). The clinically defined area is drawn on the skin and the flexible 'skin applicator' is then orientated so that the drawn skin area is encompassed within the catheter defined surface. Using a thin pewter wire, the skin drawn area is copied on the air-adjacent surface of the applicator. Ex vivo CT simulation follows. The data are then transferred to the radiotherapy planning computer and the catheters are virtually reconstructed. The isodose curve chosen to prescribe the dose is 3 mm to 5 mm away from the skin surface. Three fractions of 8Gy are scheduled, 1 week apart, delivering a radiobiological equivalent of 48Gy of standard radiotherapy within 2 weeks. Our preliminary experience shows excellent early skin tolerance. The study is ongoing to assess efficacy and late effects.