REAL-TIME OPTICAL FEEDBACK CONTROL OF LASER LITHOTRIPSY

THE OBJECTIVE OF THIS RESEARCH IS TO INVESTIGATE THE FEASIBILITY OF UTILIZING THE CHARACTERISTIC PROMPT OPTICAL EMISSIONS GENERATED DURING PULSED-LASER LITHOTRIPSY FOR AUTOMATIC AND RAPID FEEDBACK CONTROL OF THE LASER-ENERGY DELIVERY SYSTEM. THE GOAL IS TO MINIMIZE THE RISK OF INJURYRESULTING FROM INADVERTENT IRRADIATION OF HEALTHY SOFT TISSUE. THE CONCEPT INVOLVES USING THE CHARACTERISTIC LASER-INDUCED OPTICAL SIGNALS PROMPTLY EMITTED BY CALCULI TO CONTROL A FAST ELECTRO-OPTIC BEAM SHUTTER IN THE LASER DEVICE. A SIMPLE ELECTRONIC LOGIC CIRCUIT INTERROGATES THE RESULTING OPTICAL EMISSION EARLY IN THE LASER PULSE. IF THE CHARACTERISTIC PROMPT OPTICAL EMISSIONS ASSOCIATED WITH CALCULI ARE NOT OBSERVED, THE ELECTRO-OPTIC BEAM SHUTTER IS RAPIDLY CLOSED, THEREBY PREVENTING ANY SIGNIFICANT DISCHARGEOF ENERGY FROM THE DELIVERY FIBER. IT IS ANTICIPATED THAT THIS SCHEME WILL WORK WELL WITH ANY REPETITIVELY PULSED LASER DELIVERING MICROSECOND OR LONGER PULSES.