Characterizing 3D printing in the fabrication of variable density phantoms for quality assurance of radiotherapy

Abstract Purpose To present characterization, process flow, and applications of 3D fabricated low density phantoms for radiotherapy quality assurance (QA). Material and methods A Rostock 3D printer using polystyrene was employed to print slabs of varying relative electron densities (0.18–0.75). A CT scan was used to calibrate infill-to-density and characterize uniformity of the print. Two printed low relative density rods (0.18, 0.52) were benchmarked against a commercial CT-electron-density phantom. Density scaling of Anisotropic Analytical Algorithm (AAA) was tested with EBT3 film for a 0.57 slab. Gamma criterion of 3% and 3 mm was used for analysis. Results 3D printed slabs demonstrated uniformity for densities 0.4–0.75. The printed 0.52 rod had close agreement with the commercial phantom. Dosimetric comparison for 0.57 density slab showed >95% agreement between calculation and measurements. Conclusion 3D printing allows fabrication of variable density phantoms for QA needs of a small clinic.