Determination of Optimum Wavelength for Laser Photofragmentation of Urinary Stones

Daidoh, Yuichiro; Aral, Tsunenori; Komine, Yukikuni; Nagakura, Kazuhiko; Ieda, Kazuo; Mural, Masaru; Nakamura, Hiroshi; Nakagawa, Masato; Kikuchi, Makoto; Uchibori, Masami; Inazaki, Satoshi; Wakaki, Moriaki

doi:10.1089/end.1991.5.245

Cited by 10 publications

(5 citation statements)

References 16 publications

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“…Overall, results indicated that optimal wavelengths for ablation occurred at the 3-m and 6-m high absorption bands for most urinary calculi examined (Fig. 6), as previously suggested by Daidoh et al [19] for uric acid and COM calculi. The agreement of the experimental threshold fluence and ablation depth data with the photothermal model indicates that in laser lithotripsy, unlike bone ablation recently reported by Peavy et al using the FEL, the laser wavelengths may be chosen based upon the mean optical absorption spectrum of the calculus and not the chromophores-specific absorption spectra [42].…”

Section: Discussionsupporting

confidence: 83%

“…Another possibility is that the mechanical integrity of the uric acid molecule may have been compromised by wavelength specific absorption of intramolecular bonds. In this case, the irradiance wavelengths of 3.13 and 3.64 m are associated with the energy band close to the OH group in the uric acid calculus [19].…”

Section: Discussionmentioning

confidence: 95%

“…Wavelengths used in this experiment were 2.12, 2.50, 2.94, 3.13, 3.21, 3.62, 4.00, 4.57, 4.74, 4.77, 5.00, 5.60, 5.99, 6.04, 6.17, 6.20, 6.26, 6.29, 6.31, and 6.45 m. The 2.12 and 2.94 m wavelengths correspond to the wavelengths for the Ho : YAG laser and Er : YAG laser, respectively, and served as references for comparison to results from commercial lasers. Wavelengths were chosen to correspond to the peaks, inclinations, and valleys within the infrared absorption spectra of individual calculus types referenced from Dao and Daudon [31] and Daidoh et al [19]. The absorption spectra from these references are in relative optical absorbance units (a.u.)…”

Section: B Laser Source and Deliverymentioning

confidence: 99%

“…However, the role of wavelength dependent optical absorption and its effect on urinary calculi ablation has not been extensively studied. Daidoh et al [19] have suggested that 3 and 6 m may be the optimum wavelengths for ablating calcium oxalate monohydrate (COM) and uric acid calculi because of their peak absorptions. Unfortunately, these authors did not introduce a sound theoretical or physical basis for their postulation.…”

Section: Introductionmentioning

confidence: 99%

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Free electron laser ablation of urinary calculi: an experimental study

Chan

Choi

Vargas

et al. 2001

IEEE J. Select. Topics Quantum Electron.

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Infrared laser ablation of urinary calculi was investigated as a function of wavelength to determine the relation of ablation threshold fluences, ablation depths, and optical absorption. A simple photothermal ablation model was employed to examine this relationship. Human urinary calculi composed of 95% uric acid, 95% cystine, 95% calcium oxalate monohydrate (COM), and 90% magnesium ammonium phosphate hexahydrate (MAPH) were used. Various wavelengths between 2.1 and 6.5 m were selected to perform threshold fluence and ablation depth measurements. The laser source for this study was the tunable pulsed infrared free electron laser (FEL) at Vanderbilt University. Experimental results indicated a correlation of threshold fluence and ablation depth to the optical absorption properties of the calculi. When calculus optical absorption increased, the threshold fluences decreased. Although the ablation depths increased with calculus optical absorption, results indicated that in certain calculi the ablation depth was affected by optical attenuation through the ablation plume. These observations were in agreement with the photothermal ablation model, but fractures in striated calculi at higher optical absorptions indicated the contribution of a photomechanical mechanism.

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Section: Discussionsupporting

confidence: 83%

Section: Discussionmentioning

confidence: 95%

Section: B Laser Source and Deliverymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Free electron laser ablation of urinary calculi: an experimental study

Chan

Choi

Vargas

et al. 2001

IEEE J. Select. Topics Quantum Electron.

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“…Though past works have reported IR absorption spectra for kidney stones and related materials, these reports lack quantitative information concerning k and rely on thin kidney stone sections that are subject to significant scattering. − In this work, we present absorption coefficients for six compounds commonly found in human kidney stones: calcium oxalate monohydrate (COM), calcium oxalate dihydrate (COD), hydroxyapatite (HAp), anhydrous uric acid (UA), magnesium ammonium phosphate dihydrate (MAPH), and calcium hydrogen phosphate dihydrate (CHPD). We excluded other types of stone material such as pharmaceuticals or cystine as these are typically treated through prescription or dietary adjustments, respectively.…”

Section: Introductionmentioning

confidence: 99%

Near-Infrared Absorption Coefficients in Kidney Stone Minerals and Their Relation to Crystal Structure

et al. 2022

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To quantitatively understand laser ablation of kidney stones by near-infrared (NIR) lasers, accurate measurements of physical properties related to heating and mechanical failure are needed. While light scattering varies among individual stones, absorption coefficients for the materials that form the bulk of each kidney stone are measurable when scattering is controlled. We developed methods to grow single crystals with lengths and widths >20 μm for the minerals that form kidney stones: calcium oxalate monohydrate, calcium oxalate dihydrate, calcium hydrogen phosphate dihydrate, hydroxyapatite, anhydrous uric acid, and magnesium ammonium phosphate hexahydrate. These single crystals were used with an infrared microscope to measure their NIR absorption coefficients from 1.67 to 2.5 μm. The strong correlation between single crystal NIR spectra and diffuse reflectance NIR spectra indicates little anisotropy in absorption. Most minerals absorbed more strongly at 1.94 μm than 2.12 μm, the wavelengths of thulium fiber and holmium:YAG surgical lasers, respectively. For water bearing minerals, we attribute absorption mainly to water combination modes and assign NIR absorption peaks to specific water molecules and the OH bonds thereof where possible. Reported absorption coefficients can be used to quantitatively compare both laboratory investigations of ablation and surgical experience to physical properties for the first time.

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