Abstract
Photoacoustic (PA) temperature estimation for gold nanoparticles based plasmonic photothermal therapy (PPTT) has advantages, such as high intrinsic contrast, non-invasive, two-dimension imaging, and insusceptible for hypoechoic tissue that are unavailable in current temperature measurement technologies. In this thesis, we developed a thermal strain based PA temperature imaging technique based on cross-correlation algorithm. Unlike the existing amplitude based PA temperature estimation, the thermal strain based PA temperature estimation is unaffected by problems such as fluctuation of pulse laser energy and lack of photothermal stability of gold nanoparticles for PPTT. First, we proved the feasibility of thermal strain based PA temperature imaging using computer simulations, and then we confirmed the effects of varying distributions of optical absorbers. Next we built temperature calibration tables of amplitude and thermal strain based PA estimation using data obtained in PA A-line experiments. According to the above-mentioned data, we optimized the parameters of cross-correlation analysis. In phantom experiments of plasmonic photothermal therapy, we verified the feasibility and performance of amplitude and thermal strain based PA temperature imaging on a photoacoustic array imaging system. The experimental result of thermal strain based PA temperature imaging indicated a temperature resolution of 0.17℃ for 10℃ temperature-changes. To sum up, the thermal strain based PA temperature estimation is a more stable and accurate temperature monitoring technique for plasmonic photothermal therapy than the amplitude based PA temperature estimation.