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Proceedings Paper

Characterization of calculus migration during Ho:YAG laser lithotripsy by high speed camera using suspended pendulum method
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Paper Abstract

Calculus migration is a common problem during ureteroscopic laser lithotripsy procedure to treat urolithiasis. A conventional experimental method to characterize calculus migration utilized a hosting container (e.g. a “V” grove or a test tube). These methods, however, demonstrated large variation and poor detectability, possibly attributing to friction between the calculus and the container on which the calculus was situated. In this study, calculus migration was investigated using a pendulum model suspended under water to eliminate the aforementioned friction. A high speed camera was used to study the movement of the calculus which covered zero order (displacement), 1st order (speed) and 2nd order (acceleration). A commercialized, pulsed Ho:YAG laser at 2.1 um, 365-um core fiber, and calculus phantom (Plaster of Paris, 10×10×10mm cube) were utilized to mimic laser lithotripsy procedure. The phantom was hung on a stainless steel bar and irradiated by the laser at 0.5, 1.0 and 1.5J energy per pulse at 10Hz for 1 second (i.e., 5, 10, and 15W). Movement of the phantom was recorded by a high-speed camera with a frame rate of 10,000 FPS. Maximum displacement was 1.25±0.10, 3.01±0.52, and 4.37±0.58 mm for 0.5, 1, and 1.5J energy per pulse, respectively. Using the same laser power, the conventional method showed <0.5 mm total displacement. When reducing the phantom size to 5×5×5mm (1/8 in volume), the displacement was very inconsistent. The results suggested that using the pendulum model to eliminate the friction improved sensitivity and repeatability of the experiment. Detailed investigation on calculus movement and other causes of experimental variation will be conducted as a future study.

Paper Details

Date Published: 4 March 2014
PDF: 7 pages
Proc. SPIE 8926, Photonic Therapeutics and Diagnostics X, 89261I (4 March 2014); doi: 10.1117/12.2037888
Show Author Affiliations
Jian James Zhang, American Medical Systems, Inc. (United States)
Danop Rajabhandharaks, American Medical Systems, Inc. (United States)
Jason Rongwei Xuan, American Medical Systems, Inc. (United States)
Ray W. J. Chia, American Medical Systems, Inc. (United States)
Tom Hasenberg, American Medical Systems, Inc. (United States)

Published in SPIE Proceedings Vol. 8926:
Photonic Therapeutics and Diagnostics X
Bernard Choi; Hyun Wook Kang; Brian J. F. Wong M.D.; Guillermo J. Tearney M.D.; Andreas Mandelis; Nikiforos Kollias; Kenton W. Gregory M.D.; Justus F. Ilgner M.D.; Haishan Zeng; Laura Marcu, Editor(s)

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