Estimativa da localização de tumores mamários usando o conceito de tempo de desvio térmico na presença da perfusão

• Autor(a) principal: Medeiros, Vinícius Soares
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFU
• Texto Completo: https://repositorio.ufu.br/handle/123456789/34052; http://doi.org/10.14393/ufu.di.2022.25
• topic: Câncer de mama; Breast cancer; Tempo de desvio térmico; thermal deviation time; Equação de Pennes; Pennes equation; Termografia dinâmica; Dynamic themography; Técnica experimental; Experimental technique; CNPQ::ENGENHARIAS::ENGENHARIA MECANICA::FENOMENOS DE TRANSPORTE::TRANSFERENCIA DE CALOR; Engenharia mecânica; Mamas - Câncer; Equação de calor; Tomografia

The adjustments of the circulatory system during changes due to exposure to the external environment (heat/cold) or physical activities show how much our organism can adapt to the need to produce (or reduce) energy originating from its metabolism. These adjustments go through for the variation of blood perfusion. For example, once the body is affected by its perfusion, it tends to increase the effect of reducing the internal heat generation produced by its metabolism. The behavior is precisely the opposite when exposed of cooling. Also, the impact of blood perfusion due to a change in external conditions of the surface (heating or cooling) occurs in an even more intense way in regions with higher perfusion, such as tumor cells, whose vascularization is more significant than those in healthy tissues. This different behavior may, in this case, be a key to identifying the location of the tumor. In other words, proposes here, as a tumor identification method, to observe the transient response to the surface temperature of a breast exposed to a modulated heating condition. A comparison of this response with a heath breast allows an estimate of the tumor's location. The concept used for this estimate is to determine the time that the inclusion takes to cause a change in the surface temperature profile, considering, in this case, the greater perfusion of the tumor when compared to an equivalent healthy region. This time, defined here as the time to reach the maximum thermal contrast between healthy and non-healthy breasts, is obtained parametrically considering various conditions of tumor location in a one-dimensional model in cartesian coordinates and a two-dimensional model in cylindrical coordinates. It is proposed to use numerical simulations using the COMSOL Multiphysics software and analytical solutions to represent the thermal behavior of the models studied, and verify the proposed correlation in an experimental modeling using a silicone sample.The technique successfully estimated inclusions (tumors) with a thickness (diameter) of 5 mm to 20 mm in depth, in 1D and 2D models, with an estimation error of less than 1 mm.