1991 Volume 82 Issue 4 Pages 620-627
To minimize urothelial tissue injuries by inadvertent laser irradiation during the laser stone fragmentation, we developed a novel fiber-optic analysis system which is able to distinguish the urothelial tissues from urinary stones. The reflection mode of the pulsed photo-thermal radiometry (PPTR) was employed for non-destructive tissue characterization. We developed the first fiber-optic PPTR system using chalcogenide infrared glass fibers as a transmission line. As excitation light sources for the samples, three different lasers were used in vitro and compared to select the proper excitation laser which is able to distinguish wet urinary stones from urothelial tissues. The e-folding decay time of the PPTR waveform, by which the samples are characterized, was measured as an index. The ultraviolet argon (UV Ar) laser had the best discriminative faculty. Using uv Ar laser, the e-folding decay time of calcium oxalate stones, uric acid stones and the ureter, was 239±57ms, 33±4ms, and 102±24ms (p<0.001), respectively.
The new analysis system which was composed of the fiber-optic PPTR analyzer using UV Ar laser excitation together with a thin-fibered endoscope was applied to measure the e-folding decay time of PPTR waveform of urinary stones and canine ureters in vivo general anesthesia. The e-folding decay time of calcium oxalate stones, uric acid stones and the ureter was 153±15ms, 26±3ms and 246±31ms, respectively. The canine ureter was clearly differentiable from urinary stones by the measurement of the e-folding decay time of PPTR waveform. This fiber-optic analysis system may be useful for the prophylaxis is inadvertent irradiation to the surrounding tissue during the laser stone fragmentation.
