Purpose: To evaluate and determine a 3D-applicator system for skin brachytherapy treatment.
Methods: Rectangular and curved applicators measuring 8 x 8 x 1cm with embedded tunnels fabricated using Adaptiiv software and printed on MakerBot Replicator-Z18 printer. A series of measurements were performed to check tunnel radius, radius curvature, and infill density. Physical integrity i.e., dimension, thickness, uniformity, and air gap, were assessed. For tunnel radius, three sets of applicators were printed with 1.5, 2.3, and 2.5mm tunnel radius. Each tested for obstruction using 6Fr catheter. For radius curvature, all nine were printed with 16mm-radius curvature and tested for source obstruction. For infill density, six were printed with 50, 75, 80, 85, 90, and 95%-infill density. We then delivered radiation doses to the applicators, and compared measurements to a water density equivalent applicator with 95%-infill density. Finally, an end-to-end test was performed by designing applicator for head phantom, and treatment was delivered utilizing Flexitron Afterloader.
Results: All printed applicators’ dimension and thickness were within 1.0 mm. Air gap for flat and curved applicators were within 1.4 and 2.4mm. A tunnel radius of 2.3mm fit the 6Fr catheter well, while 1.5mm did not allow passage and 2.5mm was too loose. No source obstruction was detected inside all printed applicators with 16mm-radius curvature. Radiation dose measured from applicator printed with 90%-infill density showed 2% higher than water equivalent applicator. However, only 3% printed material and 2% time was reduced in printing applicator with 90%-infill density. Applicators printed with 50 to 85%-infill density showed 11 to 27% higher dose measurement. An end-to-end test was performed successfully with a setting of 2.3mm radius, 16mm-radius curvature, and 95%-infill density.
Conclusion: This study provides a methodology to evaluate and determine settings for commercially available software and printer used in the fabrication of 3D-applicator for skin Brachytherapy treatment.
3D, Brachytherapy, Commissioning
Not Applicable / None Entered.