Zhang, Ying;
(2023)
Mitigating anatomical changes in head and neck radiotherapy.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
This thesis aims to address the issue of anatomical changes during the treatment of head and neck cancer patients. Intensity-modulated proton therapy (IMPT) shows advantages in delivering a conformal dose to the target while minimizing the dose to the adjacent normal tissue. However, in the delivery of IMPT, patients not being static can lead to dosimetric discrepancies. This thesis explores different techniques to reduce the influence of uncertainty from anatomical changes (anatomical uncertainty). In Chapter 3, anatomical variations are incorporated to reveal the robustness of a plan, thus improving the selection of a robust plan. The benefit is demonstrated in all beam arrangements used in the study. In Chapter 4, a probability model is developed to simulate major anatomical deformations at each weekly time point based on population data. For overall anatomical uncertainty prediction during treatment, the PM reduces anatomical uncertainty from 3.72±0.46 mm (no model) to 0.81±0.56 mm on average. In Chapter 5, an individual model is developed to refine the systematic prediction of population data using individual progressive information. Compared with no model, whose average anatomical uncertainty and gamma index are 4.47±1.23 mm and 93.87±0.83% at week 6, respectively, the refined individual model reduces anatomical uncertainty to 1.89±1.23 mm and improves the gamma index to 96.16±1.84% at week 6. In Chapter 6, a proposed flexible strategy creates upfront predicted replans on the predicted individual geometries from the RIM. This application of the RIM reduces the parotid Dmean by 0.53 Gy on average, achieving the minimum benefit of non-delay treatment, while the dosimetric of other organs has no significant difference with the standard replanning technique (p>0.05). This prediction-based replanning improves clinical workflow efficiency. This research integrates computational methods into IMPT treatment for head and neck patients. New perspectives for mitigating anatomical uncertainty are provided and discussed in this thesis.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Mitigating anatomical changes in head and neck radiotherapy |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2023. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Med Phys and Biomedical Eng |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10166783 |
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