TU-H-CAMPUS-TeP1-04: Novel 3D Printed Plastic Cutouts Filled with Aluminum Oxide for Same Day Electron Radiotherapy




Clinics that outsource electron cutout manufacturing may be unable to simulate and treat patients on the same day. To enable same day treatment, we investigate the use of 3D printed hollow cutouts filled with 30 grit Al2O3 powder. We verified the dosimetric equivalence of such a cutout relative to an outsourced Copper cutout.


Printing was performed using a Ultibots Kossel 250 V-Slot 3D printer and polylactic acid filament. Printing files were derived from an in-house 3D model designed to mate with a Varian 6 cm electron cone. Relative to conventional cutouts (Copper or Cerrobend), the height of the hollow plastic cutout was extended by 1.0 cm to increase attenuation. Measurements were performed for 6 MeV in solid water at dmax (1.4 cm) with Gafchromic™ EBT3 film; the cutout was kidney-shaped with a long and short axis of approximately 5 and 2 cm, respectively. The Copper cutout was based on an outline of the 3D printed cutout.A calibration film was exposed immediately after the electron irradiations. All films, including an un-irradiated one, were from the same batch. Films were scanned on an Epson 10000XL flatbed scanner. Film analysis was performed in DoseLab (MOBIUS Medical Systems, Houston, Tx).


Visual comparison of the physical cutouts revealed that the Copper cutout had a slightly smaller opening than the printed cutout. Line profiles through the registered films indicated agreement within 5% in the open section. 99.9% of pixels passed gamma analysis with 2% local percent difference, 2 mm DTA, and a 25% threshold.


Same day simulation and treatment with electrons is feasible with 3D printing of a hollow cutout filled with Al2O3. Future work will include evaluations of additional cutout shapes at different depths for higher energies. Other printing materials, such as bismuth, are being tested.