School of Physics (ETDs)

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Browsing School of Physics (ETDs) by Keyword "Beam Data Collection"

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    Feasibility and the facilitation of off-site treatment planning services at Charlotte Maxeke Johannesburg Academic Hospital
    (University of the Witwatersrand, Johannesburg, 2024) Otten, Joseph Johannes; Ngcezu, Sonwabile
    The report encapsulates the comprehensive commissioning and validation process undertaken to integrate the Varian Eclipse treatment planning system (TPS) with Elekta Versa HD™linear accelerators, enabling off-site treatment planning services (OTPS). The initiative aimed to enhance the efficiency of treatment planning and expand access to care. The process involved meticulous collection and modelling of beam data from four Versa HD™Linacs within the Eclipse system. Measurements were conducted to characterize the beam properties, including profiles, percent depth dose (PDD) curves, and output factors (OF). A pivotal aspect of the validation was the acquisition and verification of the computed tomography (CT) to electron density curve, which is crucial for accurate dose calculations. The Anisotropic Analytical Algorithm (AAA) was employed for dose calculations, with its accuracy confirmed through point dose measurements and gamma index comparisons. Fine-tuning of multi-leaf collimator (MLC) transmission and dosimetric leaf gap (DLG) parameters was achieved through iterative plan measurements and optimisations. The culmination of the validation process was the end-to-end testing, adhering to the International Atomic Energy Agency (IAEA) audit methodology, utilising CIRS phantoms (Clark et al., 2019). This testing was conducted on the clinical servers, with patient-specific quality assurance results exhibiting gamma pass rates above 90% for distance to agreement (DTA) of 3mm and a dose difference (DD) 3%, indicative of the system’s accuracy. The study demonstrated the feasibility of remote treatment planning for Elekta Linacs using the Varian Eclipse TPS. The rigorous commissioning and validation pro- cess ensured the dosimetric accuracy and quality of the integrated system. The successful validation of the Eclipse TPS for clinical use suggests that this integration could significantly streamline the planning work, potentially alleviating treatment backlogs and enhancing the delivery of care in radiation therapy.