Wickers, Sairanne;
(2025)
Radiotherapy for early breast cancer: Virtual simulation and patient alignment.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Introduction Breast cancer radiotherapy relies heavily on virtual simulation (VS). Some retained elements of two-dimensional simulation are incompatible with modern practice, increasing inefficiency and impacting body image. Aims and Objectives Aim 1: Identify VS heart and lung dose surrogates to support optimum target coverage, pre-treatment pathways and modality selection. Aim 2: Investigate the impact of permanent Indian-ink tattoos and evaluate an alternative that is visible and acceptable for people of all skin colours. Methods Correlations between the percentage of heart/lung in the VS-fields and heart/lung dose was performed. Linear regressions of a model-building cohort determined VS thresholds for clinically relevant tolerance parameters. A validation cohort confirmed the clinical model. A national survey and thematic analysis was conducted to investigate the impact of Indian-ink tattoos following breast cancer radiotherapy. A randomised controlled trial was conducted to evaluate the feasibility of non-permanent natural-coloured ink pigments. Data collected and analysed included application and alignment time, radiographer-assessed visibility, equipment acceptance, and pain scores. Results Accurate heart and lung dose VS surrogates were identified (R2= >0.9). Threshold values to meet clinically relevant dose levels, and equations to estimate heart/lung dose were provided and validated for 40Gy in 15-fraction and 26Gy in 5-fraction schedules. Permanent Indian-ink tattoos negatively impacted 51% of respondents (n = 205), affecting clothing choices (15%) and serving as a constant negative reminder (31%), due to the unnatural-colour and permanent high-visibility. 6% were positively impacted, feeling proud of their survivorship. The randomised controlled trial confirmed that natural-coloured non-permanent tattoos are feasible in terms of visibility, application/alignment time, pain and radiographer acceptance. Discussion This project was the first to identify and validate predictive VS heart and lung dose surrogates and conducted the largest survey investigating the impact of Indian-ink tattoos. This supported the randomised controlled trial that has identified a feasible alternative. Conclusion The ability to predict heart and lung dose during VS supports efficient planning and early indication if tangential radiotherapy might be associated with an unacceptably great risk of late morbidity. The impact of Indian-ink tattoos and confirmed feasibility of natural-coloured, semi-permanent tattoo pigments as an alternative, has provided the reassurance to industry and other stakeholders that this unmet need warrants investment to obtain the regulatory medical device certification of a wider range of radiotherapy tattoo pigments.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Radiotherapy for early breast cancer: Virtual simulation and patient alignment |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2025. 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 > Dept of Med Phys and Biomedical Eng |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10207521 |
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