Biomedical applications of photoacoustics for thermal therapy

This work demonstrates the feasibility of Photoacoustic tomography (PAT) and real-time photoacoustic (PA) monitoring using a single transducer prototype system to detect and/or monitor tumour growth using low absorbing targets embedded in turbid phantom and thermal lesions in tissue. A single transducer PA prototype system is build utilizing a laser system producing light in the near infra-red while untrasonic transducers detects the PA pressure waves generated. The ability to image tissue using PAT is initially demonstrated using gelatin phantoms with targets of similar optical properties to native and coagulated prostate tissue. Next, lesions in bovine muscle tissue and bovine liver are also imaged demonstrating the effectiveness of PAT tp detect lesions during thermal therapy (TT). Selective imaging is shown by varying the optical wavelength to preferentially absorb light and target specific structures which in turn produce high contrast after image reconstruction. Finally, the capability of using PA to monitor TT is explored by measuring the changes in the optical and mechanical properties of tissue equivalent albumen phantoms as a function of thermal dose on PA signals, thereby demonstrating the real time capability of this modality to monitor TT.