Laser treatment of female stress urinary incontinence: Optical, thermal, and tissue damage simulations

Luke A. Hardy, Chun Hung Chang, Erinn M. Myers, Michael J. Kennelly, Nathaniel M. Fried

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Treatment of female stress urinary incontinence (SUI) by laser thermal remodeling of subsurface tissues is studied. Light transport, heat transfer, and thermal damage simulations were performed for transvaginal and transurethral methods. Monte Carlo (MC) provided absorbed photon distributions in tissue layers (vaginal wall, endopelvic fascia, urethral wall). Optical properties (n,μa,μs,g) were assigned to each tissue at λ=1064 nm. A 5-mm-diameter laser beam and power of 5 W for 15 s was used, based on previous experiments. MC output was converted into absorbed energy, serving as input for ANSYS finite element heat transfer simulations of tissue temperatures over time. Convective heat transfer was simulated with contact cooling probe set at 0 °C. Thermal properties (κ,c,ρ) were assigned to each tissue layer. MATLAB code was used for Arrhenius integral thermal damage calculations. A temperature matrix was constructed from ANSYS output, and finite sum was incorporated to approximate Arrhenius integral calculations. Tissue damage properties (Ea,A) were used to compute Arrhenius sums. For the transvaginal approach, 37% of energy was absorbed in endopelvic fascia layer with 0.8% deposited beyond it. Peak temperature was 71°C, treatment zone was 0.8-mm-diameter, and almost all of 2.7-mm-thick vaginal wall was preserved. For transurethral approach, 18% energy was absorbed in endopelvic fascia with 0.3% deposited beyond it. Peak temperature was 80°C, treatment zone was 2.0-mm-diameter, and only 0.6 mm of 2.4-mm-thick urethral wall was preserved. A transvaginal approach is more feasible than transurethral approach for laser treatment of SUI.

Original languageEnglish (US)
Title of host publicationPhotonic Therapeutics and Diagnostics XII
PublisherSPIE
Volume9689
ISBN (Electronic)9781628419245
DOIs
StatePublished - 2016
Externally publishedYes
EventPhotonic Therapeutics and Diagnostics XII - San Francisco, United States
Duration: Feb 13 2016Feb 14 2016

Other

OtherPhotonic Therapeutics and Diagnostics XII
CountryUnited States
CitySan Francisco
Period2/13/162/14/16

Keywords

  • coagulation
  • incontinence
  • laser
  • Monte Carlo
  • simulations
  • thermal remodeling

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Radiology Nuclear Medicine and imaging

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