Dosimetric characterization of 3D printed bolus at different infill percentage for external photon beam radiotherapy. (July 2017)

• Record Type: Journal Article
• Authors: Ricotti, Rosalinda; Ciardo, Delia; Pansini, Floriana; Bazani, Alessia; Comi, Stefania; Spoto, Ruggero; Noris, Samuele; Cattani, Federica; Baroni, Guido; Orecchia, Roberto; Vavassori, Andrea; Jereczek-Fossa, Barbara Alicja
• Is Part Of: Physica medica. Volume 39(2017)
• Page Start: 25
• Page End: 32
• Publication Date: 2017-07
• Subjects: 3D printing -- Bolus -- External photon beam radiotherapy -- Low-cost 3D printer -- Infill percentage -- Density; Medical physics -- Periodicals; Biophysics -- Periodicals; Biophysics -- Periodicals; Imagerie médicale -- Périodiques; Radiothérapie -- Périodiques; Rayons X -- Sécurité -- Mesures -- Périodiques; Physique -- Périodiques; Médecine -- Périodiques; 610.153
• DOI: 10.1016/j.ejmp.2017.06.004
• Languages: English
• ISSNs: 1120-1797

Abstract

Highlights: High infill percentage corresponds to high density and high homogeneity within bolus material. Modelling bolus as a homogeneous material is satisfying for infill percentages >20%. Measured dose profile with PLA boluses are more comparable to the TPS calculated profiles. Discrepancies between calculated and measured dose distribution are within 5% for high percentage infill. Abstract: Background and purpose: 3D printing is rapidly evolving and further assessment of materials and technique is required for clinical applications. We evaluated 3D printed boluses with acrylonitrile butadiene styrene (ABS) and polylactide (PLA) at different infill percentage. Material and methods: A low-cost 3D printer was used. The influence of the air inclusion within the 3D printed boluses was assessed thoroughly both with treatment planning system (TPS) and with physical measurements. For each bolus, two treatment plans were calculated with Monte Carlo algorithm, considering the computed tomography (CT) scan of the 3D printed bolus or modelling the 3D printed bolus as a virtual bolus structure with a homogeneous density. Depth dose measurements were performed with Gafchromic films. Results: High infill percentage corresponds to high density and high homogeneity within bolus material. The approximation of the bolus in the TPS as a homogeneous material is satisfying for infill percentages greater than 20%. Measurements performed with PLA boluses are more comparable to the TPS calculated profiles. For boluses printed at 40% and 60% infill, the discrepancies between calculated and measured dose distribution are within 5%. Conclusions: 3D printing technology allows modulating the shift of the build-up region by tuning the infill percentage of the 3D printed bolus in order to improve superficial target coverage.