ESTRO 2023 - Abstract Book

S1465

Digital Posters

ESTRO 2023

The values of the Renormalization fitting parameters are here reported: a=94.13±0.55, b=-0.308±0.155 cm-1, c=- 0.033±0.096 cm-1, d=-0.016±0.001 cm-1, e=0.002±0.001 cm-1. Conclusion In this multicentric study, we effectively determined and reported the fitting parameters for profile normalization of a 6 MV FFF beam from an MRIdian MR-linac in the presence of a 0.35T magnetic field. With these parameters, it is possible to calculate penumbra, unflatness and symmetry for all square field and depth combinations.

PO-1745 Study of 3D-printing conditions of thermoplastic materials for human tissue reproducibility

A. D'Anna 1 , R. Galvagno 2 , E. Bonanno 3 , G. Borzì 4 , N. Cavalli 4 , A.M. Gueli 1 , C. Marino 4 , M. Pace 4 , L. Zirone 4 , G. Stella 1

1 University of Catania, via Santa Sofia 64, I 95123 Catania, Italy, Department of Physics and Astronomy "E. Majorana", Catania, Italy; 2 CSFNSM - Centro Siciliano di Fisica Nucleare e Struttura della Materia, via Santa Sofia 64, I 95123 Catania, Italy, Deparment of Physics and Astronomy "E. Majorana", Catania, Italy; 3 Humanitas Istituto Clinico Catanese, SP54 Contrada Cubba Marletta, 11, 95045 Misterbianco, Italy, Medical Physics Department, Misterbianco, Italy; 4 Humanitas Istituto Clinico Catanese. SP54 Contrada Cubba Marletta, 11, 95045 Misterbianco, Italy, Medical Physics Department, Misterbianco, Italy Purpose or Objective The aim of this work is to find the 3D-printing conditions of thermoplastic materials to obtain the same radiological and dosimetric response of human tissues. Regular phantoms were printed to reproduce geometry, physical density, Relative Electron Density (RED), and Hounsfield Units (HUs) of CIRS 062M phantom tissue-equivalent inserts. Determining the printing conditions would allow the creation of patient-specific anthropomorphic phantoms that can be used, for example, for End to-End tests. Materials and Methods CIRS 062M inserts geometry was designed through the Autodesk Inventor 3D CAD software, sliced using the IdeaMaker 3D slicing software, and printed by a Raise 3D Pro2 Plus based on Fused Deposition Modeling (FDM) technology. Acrylonitrile Butadiene Styrene (ABS), PolyLactic Acid (PLA), and PLA-based filament with 50% of stone powder (StoneFil™) were employed for this study. Since densities of PLA and ABS are lower than that required to reproduce the Dense Bone, we identified two different solutions for the phantom realization, i.e., a hollow PLA cylinder filled with a mixture of plaster and water, and a cylinder made up of StoneFil™. To achieve a differentiation in terms of phantoms densities, the printing parameter Infill Density(%) was ranged between 20% and 100% for PLA, ABS, and StoneFil™ prints. For PLA+Plaster phantoms, the ratio m_plaster/m_water was varied. To perform radiological and dosimetric verifications of the printed phantoms, CT and Linac measurements were carried out. Results Under the used measurement conditions, it is possible to reproduce all CIRS tissues with PLA (Adipose, Muscle, Liver, Lung (exhale) and Breast) by means of 3D printing, whereas with ABS it is only possible to reproduce Lung (inhale). In both cases, dosimetric differences were <2%. For the Dense Bone reproduction study, the same measurements were performed, and the same type of analysis was carried out. The 3D-printing conditions for the Dense Bone were determined in terms of m_plaster/m_water ratio and Infill Density(%). Better radiological and dosimetric differences were found for the StoneFil™ solution. However, in both cases differences were <2% and therefore both methods are considered suitable. Conclusion From preliminary results, it seems that materials such as ABS and PLA could be used to obtain the same radiological and dosimetric response of human tissues. Since Dense Bone cannot be reproduced through standard materials such as PLA and ABS because of their physical characteristics, two alternative solutions were identified, i.e., a hollow PLA cylinder filled