Photoacoustic Thermometry Imaging for High-intensity Focused Ultrasound
High-intensity focused ultrasound (HIFU) is a non-invasive therapy in which a tightly focused beam of ultrasound is used to rapidly heat tissue in a localised region until the cells are destroyed. In recent years, HIFU has undergone clinical trials for the treatment of cancers in many organs, including the prostate, kidney, liver, breast, and brain.
One significant challenge remaining is accurately mapping the temperature rise in tissue induced by the ultrasound waves to give a measure of the delivered dose. This is critical to ensure the cancerous regions of tissue are adequately treated, while the surrounding tissue is spared.
In this project, a novel 3D temperature imaging device will be developed based on photoacoustic tomography to assess the heating induced by HIFU transducers. In photoacoustics, short pulses of near-infrared laser light are used to generate sound waves within the tissue or sample. The generated sound waves are then detected and used to reconstruct a picture of the initial pressure distribution, which is related to the absorbed optical energy. The idea behind photoacoustic thermometry is that the conversion efficiency between absorbed optical energy and generated sound is temperature dependent. Thus, by taking photoacoustic images before and during HIFU exposure, a map of the temperature field can be obtained.
The goals of the project will be to:
- develop a lab-based real-time cylindrical photoacoustic scanning system for HIFU thermometry
- to assess different phantom and tissue materials and investigate how their conversion efficiency changes as a function of temperature, and
- to use the developed imaging system to assess the heating induced by HIFU transducers under different sonication conditions.