Multifiber excimer laser catheter design strategies for various medical a

摘要

Abstract: For the XeCl Excimer laser (308 nm, 115 ns), special design multifiber laser catheters were developed and theoretically as well as experimentally evaluated. Monte Carlo simulations showed that the penetration depth of 308 nm XeCl excimer light varied from 50 to 200 $mu@m for fiber diameters from 50 to 550 $mu@m and larger. Tissue ablation is expected to be restricted to this irradiated area. In order to ablate larger tissue areas, a flexible bundle of fibers is used introducing gaps in the irradiance distribution due to dead space in between the individual fibers. Multifiber catheters were developed for a unique neurosurgery bypass procedure and for urethra stricture surgery. Real-time, close-up, high speed video imaging showed that tissue ablation mechanism of these catheters is predominately governed by explosive short-life vapor bubbles fragmenting the tissue to small particles. In order to temper the ablation process, laser energy was delivered in 8 pulses divided over 8 sectors of a multifiber catheter (multiplexing), keeping the same fluence instead of one pulse addressing all the fibers at once. !7