Dashiell GREEN-Dosimetric Assessment of a 3D Printed Brachy Applicator Using a Forearm Phantom

Final Masters Project Presentation By: Dashiell GREEN Dosimetric Assessment of a 3D-Printed Brachytherapy Applicator Using a Forearm Phantom Relative to VMAT and Electron Therapy Abstract Objectives: Skin cancers are a major public health concern in Australia, with approximately two in three people diagnosed during their lifetime. This study aims to investigate the use of superficial brachytherapy for the treatment of lesions of the forearm using a 3D printed anthropomorphic phantom and to compare this with multiple treatment modalities. Methods: A Computed Tomography (CT) scan was obtained from an open access database and imported into 3D Slicer to undergo segmentation into soft tissue, bone marrow, and bone tissue. The Hounsfield Unit (HU) values of each of these areas were analyzed and compared with the literature and 3D printed at the tissue equivalent infill densities investigated of the chosen thermoplastic filaments. A novel 3D printed applicator was created using Thermoplastic Polyurethane (TPU) filament at infill densities in accordance with hospital Quality Assurance (QA) protocols. The flexibility of TPU was investigated for ease of application and patient comfort. Across three treatment modalities, four treatment plans were made and executed on a mock lesion delineated by a radiation oncologist. Radiochromic film was calibrated and used as the dosimeter of choice. The data was extracted from the film and subsequently compared across the four planning algorithms. Results: The anthropomorphic phantom was successfully printed with the correctly segmented anatomical areas. The Brachytherapy, VMAT and Electron therapy treatments were all executed. The absorbed dose measured by the film and the Treatment Planning System (TPS) were all in relatively high agreement with the dose to the Planning Target Volume (PTV) and Clinical Target Volume (CTV) all remaining with a 5% difference. Conclusion: This method demonstrated a cost effective method of constructing anatomically correct phantoms for use in dosimetry applications. The results presented clinically relevant dosimetric indications; however, these will depend on the size of the lesion. When taking clinical setup considerations into account, brachytherapy appears to be the most favourable treatment option for this application. ========================= For more information about UWA Medical Physics vist our: Website: https://www.uwamedicalphysics.org Weblog: http://www.uwamedicalphysics.com Facebook: / groups Instagram: / uwa_medical_physics LinkedIn: / medical-physics-uwa-11979b379 Twitter: @MedicalUwa YouTube Channel: / @medicalphysicsuwa =========================