Intensity-modulated radiotherapy (IMRT) for gynaecological malignancies aims to reduce toxicity and improve tumour control. However, there are several barriers to its uptake in clinical practice. Amongst these are that of pelvic organ motion, whereby due to motion of the target organs on treatment there is a risk of geographical miss with IMRT. Secondly, although new IMRT techniques may improve bowel toxicity there is limited knowledge about dose-volume constraints for bowel, making it difficult to assess whether new techniques are likely to translate into clinical improvements. The purpose of this thesis is to address these problems. Methods Dose-volume constraints for late bowel toxicity are investigated initially through systematic review, followed by a dose-volume study based on toxicity data from pelvic radiotherapy patients. Pelvic organ motion is assessed in a systematic review examining organ motion patterns and potential strategies to account for this. Population-based and adaptive margin strategies are investigated in modelling studies for both definitive cervical cancer patients and post-hysterectomy patients. Results Initial systematic review of the literature, followed by the analysis of the toxicity and dosevolume data of 203 pelvic radiotherapy patients highlighted anal canal, bowel loops, bowel bag, sigmoid and large bowel as important organs at risk (OARs) for bowel toxicity. Dosevolume constraints were derived for these organs. Pelvic organ motion was found to be a significant problem for gynaecological IMRT. Adaptive margin strategies, such as plan-of-the-day, were demonstrated to achieve both CTV coverage whilst reducing dose to the OARs compared to standard margins and population-based margins. Conclusions Dose-volume constraints derived for late bowel toxicity, if validated with independent data, may be used to reduce bowel toxicity in future patients, and as a benchmark to assess the efficacy of new IMRT techniques. Adaptive strategies for gynaecological cancers appear a promising solution for organ motion management.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:704955 |
| Date | January 2016 |
| Creators | Jadon, Rashmi |
| Publisher | Cardiff University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://orca.cf.ac.uk/98750/ |
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