HIGH-DOSE RATE (HDR) IR-192 BRACHYTHERAPY APPLICATION OF BASAL CELL CARCINOMA

Objectives: High dose rate (HDR) surface (skin) brachytherapy uses Iridium-192 source and places it in close proximity to the target lesion using a remote afterloader and delivers it precisely on specified depth from specialized catheters or applicators that are applied to the target tissue. HDR brachytherapy performs direct radiation dose delivery to the surface with rapid falloff thereby sparing deeper healthy tissues. The treatment is painless and noninvasive and may also result in less tissue destruction and scarring in sensitive facial areas such as the nose, ear, lip etc. Because of it's localized effect and possible hypofractination, the overall treatment time is significantly less than external beam radiotherapy, with faster recovery times than invasive techniques. Methods: Conformable custom moulds are often used for irregular surfaces like the ear or nose. In this case, custom moulds were constructed from thermoplastic material. Treatment catheters were fixed to the material, providing a custom fit to the treatment target. A great care was taken to ensure that the catheters met the afterloader's minimum turn radius so that the source wire (Ir-192) could easily move through catheters. Treatment times were optimized in treatment planning system using Brachyvision software from Varian. Doses ranging from 45 - 50Gy in 10-15 fractions (5 times a week) were prescribed to 15 patients with basal cell carcinoma. Prescribed doses were delivered 5-10 mm in depth. An additional lead eye plaques were placed under thermoplastic mask for radiation protection where needed. Results: 15 patients with basal cell carcinoma (15 lesions) were treated with 50 Gy (in 10 fractions) or45 Gy (in 15 fractions) during the period 2009-2015. Alllesions resolved with treatment and there have been no recurrences reported to date. Conclusions: With excellent local control rates, cosmetic out-comes, and minimal long-term toxicities, HDR brachytherapy with surface applicators should be considered to be among the first options for treatment of basal-cell-carcinoma patients.