Monitoring cell and tissue damage during ablation by high-intensity focussed ultrasound

Thesis

High Intensity Focussed Ultrasound (HIFU) ablation is a promising technology for the non-invasive, targeted treatment of certain types of cancer. The technique functions by subjecting tumours to a cytotoxic level of intense, localised heating, while leaving the surrounding tissue unharmed. However, a number of limitations in the available HIFU treatment monitoring methods are currently hampering the effectiveness and clinical adoption of the therapy.

This work aims to develop improved metrics of HIFU-induced biological damage that are specifically suited to monitoring and controlling HIFU ablation. Firstly, an optical method that enables straightforward quantification of thermal damage in protein-embedding hydrogels is developed. Secondly, hydrogels embedded with different cell lines are used to assess the performance of common temperature-based metrics of cell death across a range of HIFU-relevant conditions. Finally, a novel, passive acoustic detector designed for the real-time monitoring of HIFU-induced tissue damage is proposed. The detector is shown to predict lesioning with over 80% accuracy in regimes that are very likely to create lesions (60 J of acoustic energy or more), with an error rate of less than 6% for exposures that are too short to cause lesioning (up to 1 s long). The proposed detector could therefore provide a low-cost means of effectively monitoring clinical HIFU treatments passively and in real time.

Authors: Nandlall, S; Sacha Nandlall

• Publication date: 2011
• DOI: 10.5287/ora-448qnenk9
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: ablation; biomedical engineering; cancer therapy; ultrasound; HIFU
• Subjects: High Intensity Focussed Ultrasound (HIFU); Technology and Applied Sciences; Medical sciences; Oncology; Biomedical engineering; Medical Engineering; Engineering & allied sciences