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Leila Shelley

Advancing dose-toxicity understanding using novel imaging techniques to improve patient outcomes in radiotherapy

Radiotherapy remains one of the most potent curative treatments for cancer, but for many common cancers, up to half of patients treated experience some degree of toxicity. A reduction in this incidence of adverse outcome would benefit patients, provide major benefits to society, and costs savings to the NHS.

My PhD project will provide bioengineering models and analysis tools to predict tissue-tracked dosage mapping. In turn, these will guide the development of patient-specific radiotherapy protocols. The project is embedded within the VoxTox Research Programme (www.voxtox.org) and benefits from the links between Oncology, Medical Physics, Engineering and the Cavendish Laboratory.

My research will address the following areas:

  • Anatomical structural models using finite element analysis to predict tissue deformations
  • Biomechanical models to construct dosage history on an individual patient basis; correlating predictions with measured clinical outcomes
  • Analysing rectal toxicity experienced by prostate cancer patients using dose-surface maps of cumulative dose
  • Using dose-volume maps to quantify radiation response for sensitive organs in head and neck cancer patients
  • Using dose-toxicity data to create in-silico models of irradiated normal tissue to develop sophisticated clinical models of toxicity
  • My project will expand upon conventional models to further our understanding of the link between radiation dose and toxicity. This will enable greater individualisation of patient treatment, with potential for adaptive radiotherapy to improve clinical outcomes; minimising side-effects whilst optimising tumour targeting.

Figure 1 – Rectal position has been found to vary two to three times greater than previously predicted during prostate radiotherapy. Shown above are axial slices at the same level from two patients: (a) and (c) show the anatomy on the kilovoltage (kV) scans used for planning prior to treatment, (b) and (d) show megavoltage (MV) images acquired during treatment displaying positional and loading differences. Images courtesy of Scaife, J., et al., Br J Radiol, 2014; 87: 20140343

Figure 2 – Dose surface maps of the rectum during prostate radiotherapy, generated from the original kilovoltage planning scan (left) and megavoltage on-treatment image (right). Differences in high- (red) and intermediate- (yellow) dose regions can be attributed to anatomical positional variation and have previously been linked to toxicity effects. The additional information provided by this novel on-treatment imaging and analysis technique will allow improved correlation between accumulated dose and patient reported side-effects. Images courtesy of Dr Simon Thomas, Head of Medical Physics and Clinical Engineering, Addenbrooke’s Hospital, Cambridge University Hospitals.