Room: Davidson Ballroom A
Purpose: High dose rate (HDR) brachytherapy of complex superficial skin lesions requires the use of custom-shaped applicators. The flexure and extent of the disease site dictates the complexity of the applicators. Securing the applicator with medical bandage wraps or thermoplastic material can obstruct visualization of the source during treatment. Any unintended shift in dwell locations would then be undetected. Dosimetric errors are also caused by incorrect connection of catheters to transfer tubes. Verification of the fidelity of this process often relies on verbal confirmation between physicists, physicians, and therapists. A method for visual real-time tracking of the source would overcome the inadequacy of the present QA processes and is presented here.
Methods: 5mm scintillation dots (SDs) were fabricated from LYSO scintillator powder and polymer. Illumination of SDs upon irradiation was monitored with a commercial camera. To verify catheter-transfer tube connections, SDs were attached to each channel of a Freiburg Flap with and without a thermoplastic material overlaid, and irradiated with an Iridum-192 source. To determine if the source reached the edge of the target, SDs were placed along the periphery. The HDR source was visually tracked by following the dazzle from SDs.
Results: SDs generated blue visible light upon irradiation and were illuminated when the source was in the corresponding catheter of the flap, close to the SDs, both with and without thermoplastic material overlaid. Cross-talk from adjacent catheters was <50% of the maximum light intensity. SDs illuminated when placed at various positions around the periphery of the target only when the HDR source was underneath it.
Conclusion: A QA technique was developed for brachytherapy surface applicators for verification of catheter-transfer tube connections and monitoring source location during treatment. This direct visualization of the source allows real-time verification, prevention of misadministration, and could be integrated into existing pre-treatment QA strategies.
Not Applicable / None Entered.