BACKGROUND AND OBJECTIVE: The purpose of this study was to develop a feedback control system for the pulsed holmium:YAG medical laser that enhances tissue selectivity and safety by discriminating between soft and hard biological tissue such as urinary and biliary calculi and bone. STUDY DESIGN/ MATERIALS AND METHODS: The ability to discriminate is achieved by monitoring prompt laser-induced visible/NIR photoemissions via retrograde transmission over the laser delivery fiber in conjunction with a developed detection algorithm. RESULTS: Experimental data are presented for a system that employs this discrimination scheme with an electro-optic shutter for rapid intrapulse feedback control of holmium laser-based lithotripsy procedures. The results demonstrate the feasibility of a lithotriptor that can deliver 1 J per pulse to calculi yet limit errant discharges to surrounding urinary tract tissue to < or = 0.1 J. CONCLUSION: Based on animal tissue safety data, the laser margin of safety is improved by an order of magnitude.
BACKGROUND AND OBJECTIVE: The purpose of this study was to develop a feedback control system for the pulsed holmium:YAG medical laser that enhances tissue selectivity and safety by discriminating between soft and hard biological tissue such as urinary and biliary calculi and bone. STUDY DESIGN/ MATERIALS AND METHODS: The ability to discriminate is achieved by monitoring prompt laser-induced visible/NIR photoemissions via retrograde transmission over the laser delivery fiber in conjunction with a developed detection algorithm. RESULTS: Experimental data are presented for a system that employs this discrimination scheme with an electro-optic shutter for rapid intrapulse feedback control of holmium laser-based lithotripsy procedures. The results demonstrate the feasibility of a lithotriptor that can deliver 1 J per pulse to calculi yet limit errant discharges to surrounding urinary tract tissue to < or = 0.1 J. CONCLUSION: Based on animal tissue safety data, the laser margin of safety is improved by an order of magnitude.