High dose-rate microselectron molds in the treatment of skin tumors

Abstract

Purpose : The feasibility of high dose rate iridium afterloaded molds in the treatment of skin tumors. Methods and Materials : Expanded silicone rubber and bronchial applicator tubes were used in the construction of various molds. The number of tubes used and the separation between them depends on the size and area to be treated. Source dwell position and time are set to follow Paterson—Parker rules. Single plane expanded silicone rubber molds between 15 × 15 mm and 60 × 70 mm were used in 120 different sites, and of the others, seven were perspex double molds, two were cylindrical applicators, and one was a partially shielded intranasal applicator. One hundred and thirty lesions of various site and histology were treated in all. After exclusion of treatments that were combined with either external beam or chemotherapy, 106 lesions (76 patients) were evaluated. Results : Full response was obtained in all but four basal cell carcinomas. The acute reaction ranged from moist desquamation (27 sites) to erythema only. Follow-up at 5 or more months revealed no changes whatever in 47 sites; 53 showed an excellent cosmetic outcome, although slight changes in pigmentation or minimal atrophy was demonstrable and 6 sites became noticeably atrophic with patchy pigmentation. For 9.6 months of average follow-up time, no recurrences have been observed. Conclusion : The high-dose-rate iridium-loaded skin applicators offer the possibility of improved therapeutic ratio in the treatment of superficial skin tumors. With the availability of a high-dose-rate afterloader this technique is simple and straightforward.