Laser lithotripsy: in-vitro comparison of different systems

Physical mechanisms of microsecond laser lithotripsy in the visible range are discussed. Theoretical model for the case ofstones which can be represented as a high-scattering low-absorption medium containing high-absorptive organic micropores is developed. The evolution of the state for such individual pore under the influence of laser radiation is described.Governing equations are derived and it was shown that there exists avalanche-like process of pore absorption increase due to the process of pyrocarbon generation. This generation is caused by the thermochemical dissociation of pore organic matter. Such effect leads to the increasing of laser pulse energy absorption and pressure front formation. This front may account for destruction of significant layer of the stone surface.Plasma can not flush under the conditions typical for described process. It starts play significant role only after primary stone destruction produced by proposed mechanism. Sharp increasing of stone absorption and modification of the destructed layer state may be considered as a good boost for the later effective plasma generation.

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“…(4) It is clear that the total gas volume Vss is the sum of two volumes -gas in the pore 1ss and gas in the cracks 1' (see Fig. 2).…”

Section: Equation Of Statementioning

confidence: 98%

Physical mechanisms of laser-induced shockwave lithotripsy with microsecond laser pulses

et al. 1994

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<title>Microsecond shockwave laser lithotripsy: analysis of induced absorption mechanisms</title>

et al. 1994

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Theoretical model of microsecond shockwave laser lithotripsy is developed. The destroying stone is considered to be a medium with low absorption and high scattering which contains high-absorptive organic inclusions. Laser radiation penetrates deep into such type of media and bulk destruction processes may occur in its significant volume. The distribution of energy fluence in stone volume was found in diffusion approximation.The evolution ofstate for each individual inclusion was studied. It was shown that the organic matter thermochemical decomposition plays important role here. Such process leads to gas and high-absorption pyrocarbon generation. It produces sharp increasing of pore volume, cracks formation, and results shockwave generation. These processes change the state of illuminated stone layer -lead to the formation of highly absorptive loose composition. Such layer change -predesirtsction -produces conditions for the later effective transformation of laser energy. Some important dependencies for such processes were found both in simplified analytical form and numerically.Computer simulation for described model of microsecond laser lithotripsy was done with the parameters typical for ruby microsecond laser. Obtained results give the basis for the estimation of lithotripsy efficiency.

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Laser lithotripsy: in-vitro comparison of different systems

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Physical mechanisms of laser-induced shockwave lithotripsy with microsecond laser pulses

Physical mechanisms of laser-induced shockwave lithotripsy with microsecond laser pulses

<title>Microsecond shockwave laser lithotripsy: analysis of induced absorption mechanisms</title>

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