Dissertação
Monte Carlo simulations and analysis of experimental data of a clinical proton therapy system using adaptive-aperture EVALUATED
Objective: Radiotherapy aims to destroy tumours with radiation while minimizing dose to healthy tissues. Compared with conventional photon treatments, protons have potentially higher precision. This work explores the potential of Mevion S250i proton therapy system’s dynamic collimator (referred to as adaptive aperture (AA), to sharpen the lateral penumbra and to decrease the dose deposition in healthy tissues. This work also aims to validate the Monte Carlo model of the AA. Methods: Different geometries (regular and irregular) at different depths (shallow and deep) were modelled using the treatment planning system (TPS) including and excluding the AA component. The plans were irradiated with a single-field and a prescribed dose of 2.00 Gy. The measurements were compared against TPS and Monte Carlo (MC) simulations using an in-house developed beam model. Results: The use of AA allowed to reduce the irradiated field within 13% (shallow plans) and 20% (deeper plans). Lateral penumbra with AA decreased at least 3 mm for the deeper target and 8 mm for the shallower (regular geometry). The relative error between MC simulations and TPS profiles is below 5%. This error is larger when the AA is used. MC simulations present a lower entrance dose compared to the TPS. Conclusions: The collimating function of the AA allows significant healthy tissue dose sparing in the area surrounding the tumour. MC beam model reveals good agreement with TPS. Advances in knowledge: The use of dynamic collimators can improve proton pencil scanning techniques.
novembro 27, 2019, 16:0
Publicação
Obra sujeita a Direitos de Autor
Orientação
ORIENTADOR
Patrícia Carla Serrano Gonçalves
Departamento de Física (DF)
Professor Auxiliar Convidado
