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Aplicação de métodos de classificação do fotótipo da pele ao planeamento de terapias de dor por fotobiomodulação na região orofacial
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A eficácia da fotobiomodulação (FBM) no tratamento da dor orofacial é frequentemente
comprometida pela variabilidade entre indivíduos na pigmentação cutânea e morfologia
tecidual. Esta dissertação teve como objetivo principal desenvolver uma abordagem
integrada para classificação objetiva do fotótipo cutâneo e respetiva aplicação ao
planeamento dosimétrico personalizado em FBM. A investigação compreendeu dois
estudos sequenciais: um estudo computacional, baseado em simulações de Monte Carlo
para modelar a propagação da luz laser (660 nm e 808 nm) num modelo de quatro
camadas do tecido da bochecha, e um estudo laboratorial que avaliou a correlação entre
a escala de Fitzpatrick e métricas de pigmentação obtidas por espectrofotometria de
refletância difusa.
As simulações computacionais identificaram a espessura da camada de gordura
subcutânea como o fator mais crítico para a atenuação da fluência muscular (reduções
>90%), superando o impacto da melanina epidérmica (variação de 46%). Desenvolveuse ainda um modelo preditivo de aprendizagem automática com elevada precisão (R² ˜
1) para estimativa de doses teciduais. Paralelamente, no estudo laboratorial, uma
amostra de 67 participantes foi caracterizada através do questionário de Fitzpatrick e
submetida a medições de reflectância no antebraço, permitindo calcular e comparar dez
métricas objetivas de pigmentação. Os resultados demonstraram que o Índice de
Melanina por Log-Ratio Escalado (? = 0,67) e o Índice de Melanina por Diferença de
Densidade Ótica (? = -0,66) apresentaram as correlações mais robustas com a escala de
Fitzpatrick. A integração dos resultados demostrou que a combinação de métricas
objetivas de pigmentação, particularmente as validadas neste estudo, com modelos
computacionais de dosimetria permite uma personalização mais precisa dos protocolos
de FBM. Conclui-se que esta abordagem integrada contribui para a maximização da
eficácia terapêutica na região orofacial, ao considerar simultaneamente as características
morfológicas e de pigmentação individualizadas.
The effectiveness of photobiomodulation (PBM) in the treatment of orofacial pain is often compromised by variability between individuals in skin pigmentation and tissue morphology. The main objective of this dissertation was to develop an integrated approach for the objective classification of skin phototypes and its application to personalized dosimetric planning in PBM. The research comprised two sequential studies: a computational study based on Monte Carlo simulations to model the propagation of laser light (660 nm and 808 nm) in a four-layer model of cheek tissue, and a laboratory study that evaluated the correlation between the Fitzpatrick scale and pigmentation metrics obtained by diffuse reflectance spectrophotometry. The computational simulations identified the thickness of the subcutaneous fat layer as the most critical factor for muscle fluence attenuation (reductions > 90%), surpassing the impact of epidermal melanin (46% variation). A highly accurate (R² ˜ 1) machine learning predictive model was also developed to estimate tissue doses. In parallel, in the laboratory study, a sample of 67 participants was characterized using the Fitzpatrick questionnaire and underwent reflectance measurements on the forearm, allowing ten objective pigmentation metrics to be calculated and compared. The results showed that the Melanin Index by Scaled Log-Ratio (? = 0.67) and the Melanin Index by Optical Density Difference (? = -0.66) had the strongest correlations with the Fitzpatrick scale. The integration of results demonstrated that combining objective pigmentation metrics, particularly those validated in this study, with computational dosimetry models enables more accurate customization of PBM protocols. It is concluded that this integrated approach contributes to maximizing therapeutic efficacy in the orofacial region by simultaneously considering individualized morphological and pigmentation characteristics.
The effectiveness of photobiomodulation (PBM) in the treatment of orofacial pain is often compromised by variability between individuals in skin pigmentation and tissue morphology. The main objective of this dissertation was to develop an integrated approach for the objective classification of skin phototypes and its application to personalized dosimetric planning in PBM. The research comprised two sequential studies: a computational study based on Monte Carlo simulations to model the propagation of laser light (660 nm and 808 nm) in a four-layer model of cheek tissue, and a laboratory study that evaluated the correlation between the Fitzpatrick scale and pigmentation metrics obtained by diffuse reflectance spectrophotometry. The computational simulations identified the thickness of the subcutaneous fat layer as the most critical factor for muscle fluence attenuation (reductions > 90%), surpassing the impact of epidermal melanin (46% variation). A highly accurate (R² ˜ 1) machine learning predictive model was also developed to estimate tissue doses. In parallel, in the laboratory study, a sample of 67 participants was characterized using the Fitzpatrick questionnaire and underwent reflectance measurements on the forearm, allowing ten objective pigmentation metrics to be calculated and compared. The results showed that the Melanin Index by Scaled Log-Ratio (? = 0.67) and the Melanin Index by Optical Density Difference (? = -0.66) had the strongest correlations with the Fitzpatrick scale. The integration of results demonstrated that combining objective pigmentation metrics, particularly those validated in this study, with computational dosimetry models enables more accurate customization of PBM protocols. It is concluded that this integrated approach contributes to maximizing therapeutic efficacy in the orofacial region by simultaneously considering individualized morphological and pigmentation characteristics.
Descrição
Palavras-chave
Modelação de Monte Carlo Dor Orofacial Dosimetria Espectroscopia de Refletância Difusa Fotobiomodulação Fotótipo