Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.512762
Title: Interaction of laser radiation with urinary calculi
Author: Mayo, Michael E.
Awarding Body: Cranfield University
Current Institution: Cranfield University
Date of Award: 2009
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Abstract:
Urolithias, calculus formation in the urinary system, affects 5 – 10% of the population and is a painful and recurrent medical condition. A common approach in the treatment of calculi is the use of laser radiation, a procedure known as laser lithotripsy, however, the technique has not yet been fully optimised. This research examines the experimental parameters relevant to the interactions of the variable microsecond pulsed holmium laser (λ = 2.12 μm, τp = 120 – 800 μs, I ~ 3 MW cm-2) and the Q-switched neodymium laser (λ = 1064 nm, τp = 6 ns, I ~ 90 GW cm-2) with calculi. The laser-calculus interaction was investigated from two perspectives: actions that lead to calculus fragmentation through the formation of shockwave and plasma, and the prospect of material analysis of calculi by laser induced breakdown spectroscopy (LIBS) to reveal elemental composition. This work is expected to contribute to improved scientific understanding and development of laser lithotripsy. The results support the general model of thermal and plasma processes leading to vaporization and pressure pulses. Nd:YAG laser interaction processes were found to be plasma-mediated and shockwave pressure (~ 12 MPa) dependent on plasma and strongly influenced by metal ions. Ho:YAG laser-induced shockwaves (~ 50 MPa) were found to be due to direct vaporisation of water and dependent on laser pulse duration. The characteristics of the pressure pulse waveforms were found to be different, and the efficiency and repeatability of shockwave and the nature of the dependencies for the lasers suggest different bubble dynamics. For the Nd:YAG laser, LIBS has been demonstrated as a potential tool for in situ analysis of calculus composition and has been used for the identification of major and trace quantities of calcium, magnesium, sodium, potassium, strontium, chromium, iron, copper, lead and other elements.
Supervisor: Ahmad, S. R. ; Bellerby, John Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.512762  DOI: Not available
Keywords: Laser ; Laser beams ; Laser radiation ; Laser ignition ; Urolithias ; Urinary system ; Lithotripsy
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