Limitations of current ureteroscope illumination configurations include presence of shadows and hot spots in images, further degraded by stone debris during laser lithotripsy, which may result in a decrease in stone ablation efficiency, increase in surgical operation time, and potential collateral tissue trauma. Previous studies have reported accidental ureteral tissue perforation from Nitinol stone basket wires during Holmium laser lithotripsy, due in part to poor visibility. Although saline irrigation is routinely used during ureteroscopy to flush stone debris and improve visibility, sub-optimal illumination may still compound these problems. Current illumination geometries and sources are inadequate to produce necessary uniform illumination for optimal visibility and safety during ureteroscopy. By moving away from single and double point source geometry and towards a ring configuration, illumination becomes more uniform in both axes, reducing shadows and increasing depth discernibility. Uric acid and calcium oxalate based stones were chosen for illumination and reflection spectroscopy. Porcine ureters were used as soft tissue samples for comparison. The percent difference in reflection between ureter and stones was greater than 40% for the wavelength ranges of 470-540 nm, and 600-700 nm, making these spectral regions most suitable for high contrast illumination, possibly through narrow band imaging techniques via multiple laser sources and/or optical filters. These improved ureteroscope illumination designs and approaches may potentially reduce complications due to limited visibility during laser lithotripsy and hence increase patient safety.

Date Published: 6 February 2017
PDF: 7 pages
Proc. SPIE 10038, Therapeutics and Diagnostics in Urology: Lasers, Robotics, Minimally Invasive, and Advanced Biomedical Devices, 100380P (6 February 2017); doi: 10.1117/12.2247598

Published in SPIE Proceedings Vol. 10038:
Therapeutics and Diagnostics in Urology: Lasers, Robotics, Minimally Invasive, and Advanced Biomedical Devices
Hyun Wook Kang; Kin Foong Chan, Editor(s)