Characterizing Optical Properties of Kidney Stone Phantoms
Tyler Iorizzo (Advanced Biophotonics Laboratory, University of Massachusetts Lowell, USA)
Ilya Yaroslavsky (IPG Medical, MA, USA)
Anna Yaroslavsky (Advanced Biophotonics Laboratory, University of Massachusetts Lowell, USA)
Abstract
BACKGROUND/OBJECTIVE
Lithotripsy procedures are used to break down stones trapped within a patient’s urinary system. Artificial Bego stones are often utilized as phantoms in lithotripsy studies. To ensure accurate dosimetry in laser lithotripsy studies, the optical properties of stone phantoms must be characterized. Thus, the goal of this study was to determine the stone phantom optical properties, and to investigate the changes of the latter due to water.
MATERIALS AND METHODS
Total transmittance, collimated transmittance, and diffuse reflectance measurements of stone samples were made using an integrating sphere spectrophotometry system and a 1940 nm Thulium Fiber Laser. An Inverse Monte Carlo technique was used to determine absorption coefficients, scattering coefficients, and anisotropy factors of samples from the measured transmittance and reflectance data. To analyze the effects of water on stone optical properties, samples were soaked in distilled water and measurements were made again. Measurements were made after samples were soaked for 24 and 72 hours.
RESULTS
Two stone samples were investigated so far. Prior to soaking in water, samples had an absorption coefficient of 1.47±0.18 mm-1, scattering coefficient of 30.5±5.93 mm-1, anisotropy factor of 0.85±0.01, and reduced scattering coefficient of 4.61±0.66 mm-1. After soaking in distilled water for 24 hours, the absorption coefficient was 1.42±0.04 mm-1, scattering coefficient was 42.3±4.63 mm-1, anisotropy factor was 0.92±0.01, and reduced scattering coefficient was 3.52±0.14 mm-1. And after 72 hours, soaked stone samples had an average absorption coefficient of 1.56±0.04 mm-1, scattering coefficient of 53.0±11.7 mm-1, anisotropy factor of 0.93±0.01, and reduced scattering coefficient of 3.80±0.11 mm-1.
FUTURE WORK
Future studies will focus on determining the optical properties of natural stones. Comparing the optical properties of artificial and natural stones will assess the role of stone phantoms for optimizing laser-based lithotripsy procedures.
Speaker
Tyler Lorizzo
Advanced Biophotonics Laboratory, University of Massachusetts Lowell, USA
United States of America
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