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

Luke A. Hardy; Chun-Hung Chang; Erinn M. Myers M.D.; Michael J. Kennelly M.D.; Nathaniel M. Fried

doi:10.1117/12.2208126

29 February 2016 Laser treatment of female stress urinary incontinence: optical, thermal, and tissue damage simulations

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

Proceedings Volume 9689, Photonic Therapeutics and Diagnostics XII; 96891R (2016) https://doi.org/10.1117/12.2208126
Event: SPIE BiOS, 2016, San Francisco, California, United States

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.

Citation Download Citation

Luke A. Hardy, Chun-Hung Chang, Erinn M. Myers M.D., Michael J. Kennelly M.D., and Nathaniel M. Fried "Laser treatment of female stress urinary incontinence: optical, thermal, and tissue damage simulations", Proc. SPIE 9689, Photonic Therapeutics and Diagnostics XII, 96891R (29 February 2016); https://doi.org/10.1117/12.2208126

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