Thursday, October 5, 15:30
Title: Tomography using light and sound
Optical imaging uses visible or near-infrared light to interrogate internal properties of biological tissues based on endogenous (for example oxygenated and deoxygenated haemoglobin) or exogenous (contrast agents) contrast. Several optical imaging modalities have been developed, and these techniques are of great interest due to the special contrast that rises from the physiological nature of light absorbing molecules. One example of tomographic imaging techniques based on light is diffuse optical tomography. In diffuse optical tomography, distributions of optical parameters inside an imaged target are estimated from light transport measurements made on its boundary. This is a highly ill-posed inverse problem, and the technique can be used to provide images with a unique contrast. However, it suffers from a low resolution due to the diffuse behaviour of light in biological tissues. Utilising so-called coupled physics imaging can overcome the limitations of diffuse imaging modalities. Perhaps the most developed of these coupled techniques is photoacoustic imaging, that combines the contrast of light with the resolution of ultrasound utilising the photoacoustic effect. In this talk, I will discuss tomography using light and ultrasound with the focus on modelling and inverse problems. Principles of diffuse optical tomography and photoacoustic tomography together with the applications are reviewed. Furthermore, problem of quantitative tomography is discussed.