Laser ablation of gall bladder stones

Study of laser interaction with calculi is presented. A system of Nd-Yag an d Ho-Yag pulsed lasers were used to produce fluorescence and plasma signals at the stone surface surrounded by saline and bile fluids. Fourth harmonic from Nd-Yag laser was transmitted to the samples by graded UV optical fibr es. Gall bladder stones of various compositions were subjected to the high power Ho-Yag laser. Temporal transients and spectral evolution of plasma an d fluorescence signals were monitored by a streak camera. A profile of acou stic pressures generated by shock waves was recorded with sensitive hydroph ones placed in the surrounding fluids. Ablation threshold, cavitation proce ss and fluorescence dependence on the laser parameters were studied in deta il. Potential of stone identification by fluorescence and possible hydrodyn amic model for ablation of biological samples is discussed. (C) 1999 Elsevi er Science B.V. All rights reserved.