在體外震波碎石術ESWL中，由水中電極高壓放電產生震波，經由橢圓反射凹面反射聚焦來擊碎人體腎結石，。在這過程中，腎結石會被擊碎之外，但同時腎臟組織也會受到不同程度之傷害。
在近三十年的研究中，針對於傳遞介質改變以減少組織傷害的研究方面，不論是實驗或是數值模擬仍然有限，因此本論文主要藉由一些實驗法來驗證，在不同介質條件下，體外震波碎石術對於組織傷害的影響程度，期望能藉由改變傳遞震波介質，與反射凹面的條件下，以探討它們對於結石分解與組織傷害的影響。以尋求減低組織傷害的治療方式，並且提供作為體外震波碎石術性能改進的依據之一。
在次本研究中發現，在不同介質方面，添加了表面張力比原來傳遞介質真空除氣水水小的介質，以及黏度比原來傳遞介質真空除氣水水高的介質時，的確有助於張力的減小，而且其正壓力與張力的比率會有提昇的趨勢，增加導電度也會減低水電式碎石機的張力。當反射震杯上覆蓋聚氨甲酸乙酯(pu)時，震波反射型態會改變，一部份由原反射震杯所反射，一部份由pu所吸收儲存能量後釋放，形成兩個聚焦波前，此種狀況對於碎石的效果有絕對的幫助。而且在張力的部分，pu也相同具有吸收張力的功能，因而減少組織傷害，水電式碎石機所能夠利用的能量因此也增加。

Under the process of extracorporeal shock wave lithotripsy(ESWL). A focused pressure pulse produced by an underwater explosion at the focus of a rigid reflector was been used clinically to fracture kidney stone. However, in the process it not only fractured the kidney stone but also induced tissue damage.
In recent 30 years, there are few investigations by either experiments or simulations on the variation of discharge media for ESWL performance. In this study, it is expected that with the change of the discharge characteristics of the mechanism on tissue damage can be relieved and the performance of extracorporeal shock wave lithotripsy(ESWL) can be improved.
With the study on the tissue damage under various discharge media, it has been observed that with the increasing on the medium coefficient of cubical expansion as well as the electric conductivity both can reduce the tensile stress and can increase the positive pressure to tensile stress ratio. With a layer of polyurethane on the surface of rigid reflector, the type of reflects shock wave is different. There exist two shock waves across the focusing region. The first focusing shock wave was reflected from the surface of rigid reflector, and the second shock wave was reflected from the polyurethane coated surface named as a pressure-released reflector surface. The tensile stress was decreased, as the stress been absorbed by the polyurethane material. However, no much change been down on the positive pressure. Therefore, with the polyurethane coated reflector, it can ease the tissue damage. The double pulse shock waves which can fracture kidney stone more efficiency also.

[1] E. Bailitis, “Schallimpuls Eines Flüssigkeitsfunkens[The Pressure Pulse of a Liquid Spark],” Zeitschrift für angewandte Physik einschlieβlch Nukleonik, Vol. 9, pp. 429-434, 1957.
[2] E. Häusler and W. Kiefer, “Anregung von Stosswellen in Flüssigkeiten durch Hochgeschwindigkeitswassertropfen[Generation of Shock Waves in Liquid by High-velocity Water Drops],” Verh Dtsch Physik Ges, Vol. 10, pp. 36, 1971.
[3] C. Chaussy, E. Schmiedt, D. Jocham, J. Schuller, H. Brendel and B. Liedl, “Extracorporeal Shock-Wave Lithotripsy (ESWL) for Treatment of Urolithiasis”, Journal of Urology, Vol. 93, pp. 59, 1984.
[4] C. Chaussy, E. Schmiedt, D. Jocham, W. Brendel, B. Forssmann and W. Walther, “First Clinical Experience with Extracorporeally Induced Destruction of Kidney Stones by Shock Waves,” Journal of Urology, Vol. 127, pp. 417-420, 1982.
[5] J. Simon, A. Corbusier and L. A. Merdes, “Extracorporeal Shock Wave Lithotripsy for Urinary Stone Disease,” European. Urol., Vol., 16, pp. 7-11, 1989.
[6] B. Sturtevant, “Shock Wave Physics of Lithotriptors,” in Smith’s Textbook of Endourology, Quality Medical Publishing, Inc., pp. 529-552, 1996.
[7] T. Patrick, B. Finlayson, J. Robert, H. Gossip, C. Wallace, R. Walker, S. Walck and M. Nasr, “Measurement of Shock Wave Pressures Used for Lithotripsy,” Journal of Urology, Vol. 136, pp. 733-738, 1986.
[8] M. Müller, “Experimental Investigations on Focusing of Weak Spherical Shock Waves in Water by Shallow Ellipsoidal Reflectors,” Acustica, Vol. 64, pp. 85-93, 1987.
[9] 楊智光，“體外震波碎石機反射罩杯之設計”，國立成功大學碩士論文，1998。
[10] 李衍德，“水電型體外震波碎石機中電極棒之性能改進研究”，國立成功大學碩士論文，1999。
[11] 顏志成，“水電型體外震波碎石機電極之間距控制設計”，國立成功大學碩士論文，2001。
[12] 李永平，“體外震波碎石機之震波聚焦對結石分解與組織傷害之探討” ，國立成功大學碩士論文，2002。
[13] C.J. Chuong, P. Zhong and G.M. Preminger, “Acoustic and Mechanical Properties of Renal Calculi Implications in Shock Wave Lithotripsy, ” Journal of Endourology,Vol.7, Number 6, 1993, pp.437-444.
[14] B. Sturtevant, “ Lecture Notes for Workshop on Shock Wave Physics of Lithotriptors, ” November 1997.
http://www.galcit.caltech.edu/~brad/bioscience/litho/workshop/endo/endo.html
[15] M. Lokhandwalla and B. Sturtevant, “Fracture Mechanics Model of Stone Communication in ESWL and Implications for Tissue Damage, ” Physics in Medicine Biology, Vol.45, pp.1-18, 2000.
[16] T. Kodama and Y. Tomita, “ Cavitation Bubble Behavior and Bubble-Shock Wave Interaction near a Gelatin Surface as a Study of in Vivo Bubble Dynamics, ” Applied. Physics,B 70, pp.139-149, 2000.
[17] P. Zhong I. Cioanta,S. Zhu F. H.Cocks and G. M.Preminger “ Effect of tissue constraint on shock wave-induced bubble expansion in vivo”Journal of .Acoustic. Society of America,104(5),pp 3126-3129,1998
[18] G.. Delacretaz ,K.Rink G .Pittomvils J. P .Lafaut ,H. Vandeursen and R.Boving Importance of The Implosion of ESWL-Induce Cavitation Bubbles” Ultrasound in med.&Biology., Vol21,No.1,pp97-103,1995
[19] M. R. Bailey D. T. Blackstock R. O.Cleveland and L. A.Crum,“Comparison of electrohydraulic lithotripters with rigid and pressure-release ellipsoidal reflectors.Ⅰ.Acoustic fields” Journal of Acoustic. Society of America.104(4),pp 2517-2524,1998
[20] G.B. Ben-Dor, Shock Wave Reflection Phenomena, Springer-Verlag New York, Inc., 1992.
[21] J.B. Keller, “Geometrical Acoustics. I. The Theory of Weak Shock Waves, ” Journal of Apply physics, Vol.25, pp.938-947, Aug. 1954.
[22] G.B. Whitham, “A New Approach to Problem of Shock Dynamics, Part 1, Two-Dimensional Problems, ”Journal of Fluid Mechanics, Vol.2, pp145-171, 1957.
[23] R.F. Chisnell, “The Motion of a Shock Wave in a Channel with Applications to Cylindrical and Spherical Shock Wave, ” Journal of Fluid Mechanics, Vol.2, pp.286-298, 1957.
[24] B. Sturtevant and V. A. Kulkarny, “The Focus of Weak Shock Waves, ” J Journal of Fluid Mechanics, Vol.73, part 4, pp.651-671, 1976.
[25] W. Sass, M. Braunlich, H. P. Dreyer, E. Matura, W. Folberth, H.G. Priesmeyer,and J. Seifert,”The mechanisms of stone disintegration by shock waves” Ultrasound in med.&Biology,Vol.17, pp239-243,1991.
[26] Michael R. Bailey David T. Blackstock Robin O.Cleveland and Lawrence A.Crum“Comparison of electrohydraulic lithotripters with rigid and pressure-release ellipsoidal reflectors.Ⅱ.Cavitation fields ” ”Journal of .Acoustic. Society of America, 106(2),pp 1149-1160,1999
[27]“Mixed Pressure-Release - Rigid Reflector ”
http://www.bu.edu/paclab/litho/prel.html
[28] M. R .Bailey, D. Dalecki, S. Z. Cchild, C. H. Raeman, D. P. Penney, D. T. Blackstock,and E. L. Carstensen”Bioeffects of positive and negative acoustic pressures in vivo’’ ”Journal of .Acoustic. Society of America,100,pp 3941-3946,1996
[29] L. A. Crum,”Cavitation microjets as a contributory mechanism for renacalculi disintegration in ESWL”, Journal of Urology(Baltimore), 140,pp 1587-1596,1988
[30] D.D. Howard, “ Mechanisms of Injury Associated with Extracorporeal Shock Wave Lithotripsy ” Ph.D. dissertation, California, Institute of Technology, April.1996.
[31] 何主亮”材料進階實驗(一)電漿基礎實驗”
http://140.134.144.73/laboratory/materials%20experiment/14.doc