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Otimização de procedimentos potenciando a melhoria das medidas de proteção radiológica em tomografia computorizada
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Abstract(s)
Objetivo: Considerando a frequência de realização de exames de Tomografia Computorizada (TC), o objetivo deste estudo foi a otimização da prática em TC com vista à melhoria das medidas de proteção radiológica do doente.
Material e Métodos: A metodologia aplicada foi dividida em 4 fases: (1) criação de Níveis de Referência de Diagnóstico (NRD) locais, através do percentil 75 do valor de CTDIvol (mGy) e DLP (mGy.cm) e análise das práticas/protocolos de rotina; (2) realização de testes experimentais com um fantoma antropomórfico (PBU-60); (3) atualização dos NRD após implementação de estratégias de otimização e (4) avaliação da qualidade de imagem pré e pós otimização.
Resultados: De uma forma geral, os NRD obtidos na fase 1 eram superiores aos identificados em guidelines europeias e recomendações internacionais. Após a implementação de medidas de otimização foram atualizados os NRD obtidos (CTDIvol – mGy; DLP - mGy.cm): TC CE (97; 1313), TC coluna lombar (40; 1045), TC abdominal (16; 1832) e TC tórax (14; 843). Foram obtidas diferenças estatisticamente significativas entre a fase 1 e 3 para os exames de TC CE e TC coluna lombar. A avaliação da qualidade de imagem realizada revelou um aumento mínimo de ruído nas imagens otimizadas.
Conclusão: Através da revisão das práticas e atualização dos protocolos de rotina, foram alcançadas reduções de dose para a maioria dos procedimentos. Em termos de CTDIvol foram obtidas diminuições de 10% para TC CE, 18% para TC coluna lombar, 6% para TC abdominal e 22% para TC tórax. Para o valor de DLP houve redução de 16% para TC CE, 29% para TC coluna lombar e 11% para TC abdominal. Contudo, não houve comprometimento da acuidade diagnóstica, não tendo sido identificadas diferenças significativas na qualidade de imagem após a implementação das medidas de otimização, sendo atualmente utilizados na prática diária os protocolos otimizados.
Purpose: Considering the frequency of Computed Tomography (CT) examinations, the objective of this study was to optimize the CT practice in order to improve the radiological protection of the patients. Materials and Methods: The methodology was divided in 4 phases: (1) establishing local Diagnostic Reference Levels (DRL) by 75th percentiles for CTDIvol (mGy) and DLP (mGy.cm) values and analysis of routine practices/protocols; (2) perform experimental tests with anthropomorphic phantom (PBU-60); (3) updating DRL after introducing recommendations for optimized practice and (4) evaluation of image quality before and after optimization. Results: DRL obtained in phase 1 were generally higher compared with European guidelines and international recommendations. After implementation of optimization work, the obtained DRL were updated (CTDIvol - mGy; DLP - mGy.cm): head CT (97; 1313), lumbar spine CT (40; 1045), abdominal CT (16; 1832) and chest CT (14; 843). Statistical significant differences were obtained between phase 1 and 3 for head CT and lumbar spine CT examinations. The evaluation of image quality performed demonstrate minimal increase of noise in optimized images. Conclusion: By reviewing the practices and updating routine protocols, dose reductions were achieved for the most procedures. In terms of CTDIvol were obtained decreases of 10% for head CT, 18% for lumbar spine CT, 6% for abdominal CT and 22% for chest CT. For the DLP value there was a reduction of 16% for head CT, 29% for lumbar spine CT and 11% for abdominal CT. However, there was no loss of diagnostic acuity and no significant differences in image quality were identified after optimization, so the optimized protocols are currently used in daily practice.
Purpose: Considering the frequency of Computed Tomography (CT) examinations, the objective of this study was to optimize the CT practice in order to improve the radiological protection of the patients. Materials and Methods: The methodology was divided in 4 phases: (1) establishing local Diagnostic Reference Levels (DRL) by 75th percentiles for CTDIvol (mGy) and DLP (mGy.cm) values and analysis of routine practices/protocols; (2) perform experimental tests with anthropomorphic phantom (PBU-60); (3) updating DRL after introducing recommendations for optimized practice and (4) evaluation of image quality before and after optimization. Results: DRL obtained in phase 1 were generally higher compared with European guidelines and international recommendations. After implementation of optimization work, the obtained DRL were updated (CTDIvol - mGy; DLP - mGy.cm): head CT (97; 1313), lumbar spine CT (40; 1045), abdominal CT (16; 1832) and chest CT (14; 843). Statistical significant differences were obtained between phase 1 and 3 for head CT and lumbar spine CT examinations. The evaluation of image quality performed demonstrate minimal increase of noise in optimized images. Conclusion: By reviewing the practices and updating routine protocols, dose reductions were achieved for the most procedures. In terms of CTDIvol were obtained decreases of 10% for head CT, 18% for lumbar spine CT, 6% for abdominal CT and 22% for chest CT. For the DLP value there was a reduction of 16% for head CT, 29% for lumbar spine CT and 11% for abdominal CT. However, there was no loss of diagnostic acuity and no significant differences in image quality were identified after optimization, so the optimized protocols are currently used in daily practice.
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Keywords
Tomografia computorizada Proteção radiológica Otimização Níveis de referência de diagnóstico Qualidade de imagem Computed tomography Radiation protection Optimization Diagnostic reference levels Image quality