A Workflow for Patient-Specific 3D-Printed Applicators In HDR Cutaneous Brachytherapy
Abstract
Purpose
To develop and clinically implement a reproducible workflow for designing, manufacturing, and commissioning patient-specific 3D-printed applicators for high-dose-rate (HDR) brachytherapy of complex cutaneous malignancies.
Methods
Patients requiring HDR brachytherapy for cutaneous targets underwent CT simulation using a conventional skin flap applicator constructed from commercially available materials (Varian, Palo Alto, CA). A separate CT dataset was used to design a patient-specific 3D-printed applicator using Eclipse (Varian, Palo Alto, CA) and 3D Brachy (Adaptiiv, Halifax, NS). Applicators were fabricated using a Form 3B printer (Formlabs, Somerville, MA) with BioMed Clear resin. Post-production quality assurance included evaluation of CT Hounsfield Unit (HU) consistency relative to water, spatial fidelity of applicator dimensions and source channels, and afterloader compatibility. Following fabrication, patients underwent an additional CT simulation with the 3D-printed applicator in place to confirm fit and generate the clinical treatment plan. Time required for CT simulation, and applicator design and production was recorded for both workflows. Material and labor costs were tracked to estimate relative financial impact.
Results
All 3D-printed applicators demonstrated acceptable HU values, geometric accuracy, and afterloader compatibility for clinical use. Although the 3D-printed workflow required an additional CT simulation, total CT simulation time was reduced compared to the traditional skin flap workflow due to improved initial fit and reduced on-table modification. Treatment setup time was also reduced with 3D-printed applicators. The average cost of applicator production was lower for the 3D-printed workflow compared to traditional skin flap construction.
Conclusion
A clinically viable workflow for patient-specific 3D-printed HDR brachytherapy applicators was successfully implemented. Early experience demonstrates reductions in CT simulation time, treatment setup time, and applicator production cost. Ongoing work will evaluate dosimetric differences and clinical outcomes as additional patients are treated.