Purpose: To evaluate the radiodensity of modified 3D filaments for creating patient specific anthropomorphic head and neck radiotherapeutic phantoms.
Methods: A DICOM file of a head and neck phantom was downloaded from the NIH cancer imaging archive. Using Vesalius 3 software the file was segmented to bone (226-2071 HU) and skin (-718 to -177 HU) converted to STL files and then to g-code using the 3D slicer Cura. 3D filaments with various potentially varying radio densities were prepared by melting polylactic acid (PLA) pellets at 180°C and mixing with the mineral powders listed in the Table ( Filabot EX2, Barre VT, 05641). The resulting filaments were 3D printed with either the Ender3 or CR10 models (Crealty). The resulting 3D prints were imaged on a CT scanner (Siemens) with scan parameters of 140 kV and 300mA.
Results: The measured HU values ranged from -185 for PLA without additive to 2800 for PLA containing 60% steel. PLA containing 20% Bronze (20% in-fill) had an HU result of 840 while 5% bismuth trioxide (85% in-fill) was higher at 1100. PLA containing calcium silicate was 355 (85% in fill) while human skull measured at 1500 HU.
Conclusion: The HU results for the two controls, PLA filament without additives and human skull, are consistent with prior reported values. The 20% Bronze and 5% bismuth trioxide fall within the HU range of bone. The HU result for the PLA filament is consistent with that of skin. Additional fine adjustments of the HU values can be made by varying the % of mineral content and the % in-fill density in the Cura slicer before 3D printing.
Not Applicable / None Entered.