(Sunday, 7/12/2020) [Eastern Time (GMT-4)]
Room: AAPM ePoster Library
Purpose: A phantom study to compare 3D-printed and traditionally hand-made boluses in radiotherapy for head and neck cancer
Methods: VMAT plans with drawn boluses from 5 Head and neck cancer patient were selected and the contours of organ-at-risks and targets were deformed to a humanoid phantom (CIRS, ATOM). New VMAT plans were made with the new contours. By using a commercial bolus creation software, bolus segmentation was performed and the stereolithography file was created for 3D printing. Standard PLA was used as the 3D printing material in a 3D printer (Raise3D Pro2 Plus). A hand-made wax bolus and a 3D-printed bolus were fabricated for each of these cases. After that, CT scans of the hand-made and 3D-printed boluses with the phantom were obtained, and the images were put to the VMAT plan for dose verification. A variety of comparisons were performed, including the infill density (Hounsfield Unit), fitting with the body contour and their impact on the dosimetry.
Results: The CT number of the printed and the hand-made boluses were different. Bubbles were observed in some of the hand-made boluses but not in the printed ones. Both boluses fitted the body contour of the phantom, but the 3D-printed boluses have lesser air gaps between the bolus and the body surface. Dose comparison showed that the hand-made boluses resulted in underdose region at the target, while the printed ones did not.
Conclusion: bolus resulted in better dosimetry accuracy due to the homogeneous material and the better physical resemblance to the originally drawn bolus. Meanwhile, the 3D printing technology also save patient’s time for waiting the wax production in hospital.
Keywords
3D, Dosimetry, Tissue Composition
Taxonomy
TH- External Beam- Photons: treatment planning/virtual clinical studies
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