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Otimização e implementação de um protocolo de baixa dose em tomografia computorizada do tórax
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| 3.8 MB | Adobe PDF |
Advisor(s)
Abstract(s)
A tomografia computorizada (TC) é uma técnica fundamental no diagnóstico por imagem, mas está associada a doses elevadas de radiação. Este trabalho teve como objetivo desenvolver e validar um protocolo de baixa dose em TC torácica que reduza a exposição sem comprometer a qualidade diagnóstica.
Foram realizados ensaios em fantoma com diferentes combinações de kV, mAs, Pitch e AIDR. A dose foi avaliada pelo CTDIvol e a qualidade através de métricas objetivas e subjetivas. Ajustaram-se modelos de regressão polinomial, permitindo prever relações entre parâmetros técnicos e desempenho. Com base nas previsões, geraram-se combinações adicionais e identificaram-se protocolos otimizados pela análise de Pareto.
Os resultados mostraram correlações claras entre kV/mAs e aumento da dose, e efeito redutor do Pitch. O modelo final apresentou bom desempenho (R² ajustado ~0,80), permitindo selecionar protocolos com CTDIvol entre 2,7 e 3,9 mGy e qualidade ≥10. A validação clínica em seis doentes confirmou uma redução média de 42% na dose em relação ao protocolo convencional, mantendo a qualidade de imagem aceitável.
Conclui-se que a otimização sistemática de protocolos de TC é eficaz para reduzir a dose mantendo a fiabilidade diagnóstica, em consonância com os princípios de proteção radiológica.
Computed tomography (CT) is a key imaging modality but is associated with high radiation doses. This study aimed to develop and validate a low-dose chest CT protocol that reduces exposure without compromising diagnostic quality. Phantom experiments were conducted with varying kV, mAs, Pitch, and AIDR. Dose was assessed through CTDIvol and image quality by objective and subjective metrics. Polynomial regression models were fitted to predict the relationships between technical parameters and outcomes. Based on these models, additional combinations were generated and optimized protocols identified through Pareto front analysis. Results showed clear correlations between kV/mAs and increased dose, and a reducing effect of higher Pitch. The final model performed well (adjusted R² ~0.80), allowing selection of protocols with CTDIvol between 2.7–3.9 mGy and quality ≥10. Clinical validation in six patients confirmed an average 42% dose reduction compared to the conventional protocol, while maintaining clinically acceptable image quality. In conclusion, systematic CT protocol optimization effectively reduces dose while preserving diagnostic reliability, in line with radiation protection principles.
Computed tomography (CT) is a key imaging modality but is associated with high radiation doses. This study aimed to develop and validate a low-dose chest CT protocol that reduces exposure without compromising diagnostic quality. Phantom experiments were conducted with varying kV, mAs, Pitch, and AIDR. Dose was assessed through CTDIvol and image quality by objective and subjective metrics. Polynomial regression models were fitted to predict the relationships between technical parameters and outcomes. Based on these models, additional combinations were generated and optimized protocols identified through Pareto front analysis. Results showed clear correlations between kV/mAs and increased dose, and a reducing effect of higher Pitch. The final model performed well (adjusted R² ~0.80), allowing selection of protocols with CTDIvol between 2.7–3.9 mGy and quality ≥10. Clinical validation in six patients confirmed an average 42% dose reduction compared to the conventional protocol, while maintaining clinically acceptable image quality. In conclusion, systematic CT protocol optimization effectively reduces dose while preserving diagnostic reliability, in line with radiation protection principles.
Description
Keywords
Computed Tomography Dose Optimization Polynomial Regression Pareto Analysis Low-Dose Protocols Tomografia Computorizada Otimização de Dose Regressão Polinomial Análise de Pareto Protocolos de Baixa Dose