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Abstract(s)
Introdução: Os sistemas de planeamento utilizam a informação das densidades eletrónicas, necessárias para o cálculo de dose provenientes da TC. Uma tendência recente é o uso da RM como única modalidade, usando as imagens de RM para criar uma TC sintética. Um fluxo de trabalho no qual todas as etapas pré-tratamento são realizadas na RM é favorável. O objetivo do estudo é validar a técnica MR-Only como imagem de referência na verificação do posicionamento em Radioterapia. Metodologia: Foram incluídos 13 doentes com tumor cerebral e 15 doentes com tumor retal, seguidos no Serviço de Radioterapia do Centro Clínico Champalimaud, de outubro de 2019 a junho de 2020. Com base no registo automático de 80 CBCT comparou-se os desvios entre as imagens da TC de planeamento e da TC sintética (MR-Only). Resultados: No registo das imagens do reto, a variação que se obteve foi inferior a 1,4mm longitudinal, 1mm lateral e vertical. A variação nas translações foi de -0,2±0,3mm lateral, -0,3±0,4mm vertical e de -0,4±0,7mm longitudinal. As rotações foram inferiores a 0,4º, sendo a variação verificada 0,0±0,2º pitch, 0,0±0,1º yaw e de 0,0±0,1º roll. No cérebro foi inferior a 1,3mm longitudinal, a 0,6mm vertical e a 0,4mm lateral. A variação verificada foi de -0,2±0,2mm lateral, -0,3±0,2mm vertical e de -0,4±0,5mm longitudinal. Nas rotações, obteve-se uma rotação máxima de 0,3º, sendo a variação verificada -0,2±0,1º pitch, 0,1±0,1º yaw e de 0,0±0,1º roll. Conclusão: Foi validado o registo da imagem da TC sintética com a imagem de verificação CBCT. Os desvios encontrados nos registos entre a TC de planeamento e a TC sintética da RM sugerem que é justificado o uso da técnica MR-Only como imagem de referência.
ABSTRACT - Introduction: The planning systems use the information of the electronic densities, needed for the calculation of the dose from the CT. A recent trend is the use of MR as the only modality, using the MR image to create a synthetic CT. A workflow in which all pre-treatment steps are performed at the MR is favorable. The objective of this study is to validate the MR-Only technique as the reference image in the verification of positioning in Radiotherapy. Materials and Methods: 13 patients with a brain tumor and 15 patients with a rectal tumor followed at the Radiotherapy Unit of the Champalimaud Clinical Center, from October 2019 to June 2020, were included. Based on the automatic registration of 80 CBCT, the deviations between images of planning CT and synthetic CT (MR-Only) were compared. Results: In the registration of the images in the rectum, the variation that was obtained was less than 1,4mm longitudinal, 1mm laterally, and vertically. The variation verified in the translations was - 0,2±0,3mm lateral, -0,3±0,4mm vertical, and - 0,4±0,7mm longitudinal. Regarding rotations were lower than 0,4º, with the variation verified 0,0±0,2º pitch, 0,0±0,1º yaw, and 0,0±0,1º roll. In the brain it was less than 1,3mm longitudinally, 0,6mm vertically and 0,4mm laterally. The variation found was -0,2±0,2mm lateral, -0,3±0,2mm vertical, and -0,4±0,5mm longitudinal. In the rotations, a maximum rotation of 0,3º was obtained, being the variation verified -0,2±0,1º pitch, 0,1±0,1º yaw, and of 0,0±0,1º roll. Conclusion: The registration of the synthetic CT image with the CBCT verification image was validated. The minimum deviations found in the results between the planning CT and the synthetic CT of the MRI suggest that the use of the MR-Only technique as a reference image is justified.
ABSTRACT - Introduction: The planning systems use the information of the electronic densities, needed for the calculation of the dose from the CT. A recent trend is the use of MR as the only modality, using the MR image to create a synthetic CT. A workflow in which all pre-treatment steps are performed at the MR is favorable. The objective of this study is to validate the MR-Only technique as the reference image in the verification of positioning in Radiotherapy. Materials and Methods: 13 patients with a brain tumor and 15 patients with a rectal tumor followed at the Radiotherapy Unit of the Champalimaud Clinical Center, from October 2019 to June 2020, were included. Based on the automatic registration of 80 CBCT, the deviations between images of planning CT and synthetic CT (MR-Only) were compared. Results: In the registration of the images in the rectum, the variation that was obtained was less than 1,4mm longitudinal, 1mm laterally, and vertically. The variation verified in the translations was - 0,2±0,3mm lateral, -0,3±0,4mm vertical, and - 0,4±0,7mm longitudinal. Regarding rotations were lower than 0,4º, with the variation verified 0,0±0,2º pitch, 0,0±0,1º yaw, and 0,0±0,1º roll. In the brain it was less than 1,3mm longitudinally, 0,6mm vertically and 0,4mm laterally. The variation found was -0,2±0,2mm lateral, -0,3±0,2mm vertical, and -0,4±0,5mm longitudinal. In the rotations, a maximum rotation of 0,3º was obtained, being the variation verified -0,2±0,1º pitch, 0,1±0,1º yaw, and of 0,0±0,1º roll. Conclusion: The registration of the synthetic CT image with the CBCT verification image was validated. The minimum deviations found in the results between the planning CT and the synthetic CT of the MRI suggest that the use of the MR-Only technique as a reference image is justified.
Description
Keywords
Radioterapia Registo MR-Only TC sintética Radiotherapy Registration Synthetic CT
Citation
Marques J, Caetano M, Stroom J, Greco C. MR-ONLY como imagem de referência na verificação do posicionamento em radioterapia. Roentgen. 2022;3(2):64-77.
Publisher
NUCLIRAD - Núcleo de Desenvolvimento dos Técnicos de Radiologia