Fiber fragmentation during laser lithotripsy

摘要

Abstract: Laser lithotripsy (LISL) in combination with a bare fiber can lead to fragmentation of the fiber tip. Fiber fragmentation of four lithotripsy laser systems was measured under clinical conditions (calcium sulphate stone, covered with water), a Q-Switched Alexandrite laser, a pulse-stretched alexandrite laser, and two different dye lasers were used. The threshold for fiber fragmentation for pulses of Gaussian shape was 200 MW/cm$+2$/ peak power density. The Q-Switched Alexandrite laser leads to fragmentation rates of 100mm/1000 pulses at typical pulse-energies (50mJ, 150ns), whereas fiber fragmentation did not occur if dye lasers were used (80 mJ, 1.3 $mu@s; 80 mJ, 2.5 $mu@s) due to their longer pulse-lengths and lower power densities respectively. Using a pulse-stretched alexandrite laser fragmentation could be avoided if pulse lengths above 1 $mu@s were used. During LISL the fiber fragments which are produced will be embedded in the ureter wall and therefore subsequent formation of stenoses may be possible.!