Study on dynamic mechanism of perforation on cancer cells at shock waves exposures

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Extracoporeal shock wave lithotripsy (ESWL), non-invasive removal of kidney stones, is one of the most peaceful applications of shock waves. As a collaboration project with Medical School of Tohoku University we have developed prototype lithotriptor which was approved by the Ministry of Health and Welfare. As a result of basic research, tissue damages during ESWL treatments have been clarified and we found a technology to damage living tissue in a controlled fashion. This technology is extended to cancer research with the combination of chemotherapy during which it was discovered punctuation on the cancer cells when shock waves were exposed on them. The mechanism of punctuation is found to be related with shock wave interaction with nonhomogeneity of a medium with local curvature. The goal of present research is to clarify the mechanism of the punctuation in details.Results obtained are summarized as following :(1) Optical flow visualization of shock/tissue interaction has been developed. However, it has a limitiation in its spatial resolution. In order to compensate it, we seek for model tissues which have analogous characteristics to living tissues, with which various analogue experiments have been conducted and the results have been numerically simulated.(2) Finite fringe holographic interferometry has been developed and Fourier fringe analysis was well established. This method allowed to identify a slight density change created by shock wave exposures and was found to be effectively extended further shock/tissue interaction studies.(3) Numerical methods have been developed to be compared with experiments. Interactions between shock waves and various gas liquid interfaces have been successfully simulated.(4) A vertcal gas gun has been designed and constructed with which micro-shock/tissue interaction will be investigated. This is a facility which can directly simulate shock induced perforation on model tissue surface.