ESTRO 2024 - Abstract Book

S3360

Physics - Detectors, dose measurement and phantoms

ESTRO 2024

Cetnar et al. Commissioning of a motion system to investigate dosimetric consequences due to variability of respiratory waveforms JACMP 17(1), 2016

Goddard et al. Reducing PTV margins for prostate SBRT with motion compensation and gating techniques. JACMP 24(4), 2023

2708

Digital Poster

Dosimetric characterization of new flexible materials for personalized 3D printed boluses for EBRT

Aleksandra Bochyńska, Anna Zawadzka, Agnieszka Walewska, Edyta Fujak

The Maria Sklodowska-Curie National Research Institute of Oncology, Department of Medical Physics, Warsaw, Poland

Purpose/Objective:

Although 3D printing offers many possibilities for customization, fitting a rigid individual bolus to a patient's complex anatomy in areas such as the auricle, corner of the eye or nostril may be problematic and challenging. In such cases, more flexible materials may be desirable. This work aimed to investigate the properties of materials more elastic than those commonly used in three-dimensional printing. Results for 3D printed and standard gel sheet boluses were compared.

Material/Methods:

The dosimetric properties of two types of thermoplastic polyether urethane (TPU) flexible 3D-printing filament materials (with a hardness of 93 and 40 in Shore A and Shore D scale, respectively) were investigated. Three 100 x 100 mm2 cuboid blocks with two thicknesses (5 mm, 10 mm) and two infill percentages (60%, 100%) were printed for each material. Fused deposition modelling technology FlashForge Creator 4 3D-printer was used. The samples were placed horizontally on a water-equivalent slab phantom. Percentage depth-dose (PDDs) in the build-up region were measured with plane-parallel ionization chamber Markus (PTW-Freiburg) using both flattened (FF) and unflattened (FFF) 6 MV photon beams. A fixed number of monitor units and an open field of 50 x 50 mm were set. The results were then compared with those obtained for the 5 mm and 10 mm gel boluses used as a standard in clinical practice. All of the samples were scanned with a 1.25 mm slice in Discovery RT (GE Medical Systems) CT scanner and analogous calculations for the analytical anisotropic algorithm (AAA, v 15.6) with dose grid size of 1.25 mm were performed in the Eclipse treatment planning system. The repeatability of printing was also verified by reprinting cuboids with a 5 mm thickness and 100% infill percentage with the same printing parameters applied. The calculated planar dose distributions under corresponding samples were compared using VeriSoft (v 6.1, PTW-Freiburg) software.

Results: