Avaliação de modelos numéricos para cálculo da transferência de calor na terapia fototérmica
Cancer has been the focus of researches aimed to improve therapeutic procedures. Among them is hyperthermia, including Interstitial Laser Therapy (ILT) and Plasmonic Photothermal Therapy (PPTT). Models are used for computational simulations of the therapies, and validation of them is crucial to ensu...
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| Formato: | Dissertação |
| Idioma: | pt_BR |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/58022 |
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| Resumo: | Cancer has been the focus of researches aimed to improve therapeutic procedures. Among them is hyperthermia, including Interstitial Laser Therapy (ILT) and Plasmonic Photothermal Therapy (PPTT). Models are used for computational simulations of the therapies, and validation of them is crucial to ensure simulation reliability. This study evaluates models for hyperthermia by comparing temperature distributions obtained from simulations with those from a protocol for a real ILT to treat breast cancer. Laser irradiation is administered through an optical fiber in the center of an approximately spherical tumor. The protocol includes devices to control the energy delivered to the tissue, such as a fluid pump, avoiding damage to the optical fiber tip, and probes with thermocouples to measure temperatures. The simulation covers the numerical resolution of the Bioheat Equation (PBHTM) and the Radiative Transfer Equation (RTE), with the divergence of heat flux from RTE serving as the source term in PBHTM. The numerical solution provides temperature distributions in the irradiated region, encompassing tumor and surrounding tissues. Thermophysical and optical properties of tissues were obtained from the literature, while those of the laser were based on a technical manual for the DIOMED DELTA15 lasers. The medium properties were assumed as those of a healthy breast tissue, in a cylindrical computational domain with length of 4 cm and radius of 2 cm. The tip of the optical fiber was located at the domain center. Based on the protocol, irradiation time was 2100 s, considering a semiconductor diode laser with a wavelength of 805 nm, operating at 5 W, and with a light beam diameter of 600 µm. Results were obtained to investigate the sensitivity of temperature field with respect to parameters associated to uncertainties, including laser operational mode (pulsed or continuous), positioning of thermocouples and extent of the cooling region at the tip of the optical fiber. The results obtained from the simulations showed excellent agreement with the experimental data from the protocol, increasing reliability on modeling, adopted hypotheses, and employed codes. |
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