Ultrabroadband mid-infrared Fourier spectroscopy of breath combined with supervised data analyses resulted in >95% accuracy in distinguishing healthy and prostate cancer groups. A panel of 7 revealed metabolites allowed to hypothesize their origin and transportation.
Laser lithotripsy is the preferred application for the destruction of ureteral and kidney stones. Clinically Ho:YAG lasers (λ=2.1µm) are used due to high absorption by water to induce thermomechanical ablation. This study focussed on the investigation of different laser parameters in relation to the stone destruction efficiency. Experiments were performed using clinical available Ho:YAG laser energy transferred via a standard fibre (Ø: 365µm) onto phantom calculi (Bego-Stones of different hardness) in an aquarium set-up. Dusting can be reached most efficient by using low energy/pulse (approx. 0.5J/pulse) and repetition rate of around 40 Hz. Higher energy/pulse showed strong repulsion and thereby increased mobility, while using lower repetition rates result in longer ablation times. For hard calculi the ablation process takes a much longer time compared to soft stones.
In addition the fluorescence of human urinary stones was investigated in-vitro as well as in-vivo. In-vitro investigations (n=30) were performed using fluorescence spectrometer and fluorescence microscopy techniques. Urinary stones show broad band fluorescence emission. Inhomogeneous local fluorescence sites and homogeneous surface fluorescence can be distinguished. The shell-like structure of the stones showed difference fluorescence behavior. The impact of fluorescence guidance during endoscopic laser lithotripsy will be discussed.
Laser lithotripsy is the preferred application for the destruction of ureteral and kidney stones. Clinically Ho:YAG lasers (λ=2.1μm) are used due to high absorption by water to induce thermomechanical ablation. This study focussed on the investigation of different laser parameters in relation to the stone dusting efficiency. The term dusting was defined when the ablated fragments were d<1mm in diameter while fragmentation is defined to pieces of d> 1mm. The discussion about fragment-size showed advantages like reduced surgery time.
Experiments were performed using clinical available Ho:YAG laser energy transferred via a standard fibre (Ø: 365μm) onto phantom calculi (Bego-Stones of different hardness) in a water filled vessel.
Dusting can be reached most efficient by using low energy/pulse (approx. 0.5J/pulse) and repetition rate of around 40 Hz. Higher energy/pulse showed strong repulsion and thereby increased mobility, while using lower repetition rates result in longer ablation times. With regard to the hardness of the phantoms it can be derived that on soft calculi or calculi with a very rugged surface dusting can be observed less because the stone breaks into large fragments after a short time of laser application. For hard calculi the ablation process takes a much longer time compared to soft stones.
In the following will be shown that dusting and fragmentation process depends not only on the energy/pulse and repetition rate of a Ho:YAG-laser, but also there are differences between Ho:YAG-laser systems according to the dusting efficiency.
Urinary stones harvested from patients were under in-vitro investigation. Fluorescence measurements were performed either by taking images under blue light excitation light as well as measuring excitation-emission-matrixes. Ho:YAG-laser assisted fragmentation was performed in an aquarium set-up to derived fragmentation/dusting rates. FTIR-spectroscopy was used to identify the composition of the stone. Blue light fluorescence excitation resulted in fluorescence emission in different spectral regions spectroscopically proven by EEM-measurement. A correlation with FTIR-spectroscopy is performed. Fragmentation experiments resulted in a dependency to the applied energy/pulse and repetition rate. Using photonic techniques urinary stones could be categorized by their composition. The impact of fluorescence guidance during endoscopic laser lithotripsy will be discussed.
Conference Committee Involvement (3)
Advanced Photonics in Urology 2023
28 January 2023 | San Francisco, California, United States
Advanced Photonics in Urology
6 March 2021 | Online Only, California, United States
Translation of Lasers and Biophotonics Technologies and Procedures: Toward the Clinic
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