Authors: | Park, S.; Farah, R.; Shea, S. M.; Tryggestad, E.; Hales, R.; Lee, J |
Article Title: | Evaluation of lung tumor motion management in radiation therapy with dynamic MRI |
Abstract: | Surrogate-based tumor motion estimation and tracing methods are commonly used in radiotherapy despite the lack of continuous real time 3D tumor and surrogate data. In this study, we propose a method to simultaneously track the tumor and external surrogates with dynamic MRI, which allows us to evaluate their reproducible correlation. Four MRI-compatible fiducials are placed on the patient's chest and upper abdomen, and multi-slice 2D cine MRIs are acquired to capture the lung and whole tumor, followed by two-slice 2D cine MRIs to simultaneously track the tumor and fiducials, all in sagittal orientation. A phase-binned 4D-MRI is first reconstructed from multi-slice MR images using body area as a respiratory surrogate and group-wise registration. The 4D-MRI provides 3D template volumes for different breathing phases. 3D tumor position is calculated by 3D-2D template matching in which 3D tumor templates in 4D-MRI reconstruction and the 2D cine MRIs from the two-slice tracking dataset are registered. 3D trajectories of the external surrogates are derived via matching a 3D geometrical model to the fiducial segmentations on the 2D cine MRIs. We tested our method on five lung cancer patients. Internal target volume from 4D-CT showed average sensitivity of 86.5% compared to the actual tumor motion for 5 min. 3D tumor motion correlated with the external surrogate signal, but showed a noticeable phase mismatch. The 3D tumor trajectory showed significant cycle-to-cycle variation, while the external surrogate was not sensitive enough to capture such variations. Additionally, there was significant phase mismatch between surrogate signals obtained from fiducials at different locations. |
Journal Title: | Proceedings of SPIE--the International Society for Optical Engineering |
Volume: | 10135 |
ISSN: | 0277-786X |
Publisher: | Unknown |
Journal Place: | United States |
Date Published: | 2017 |
End Page: | 10.1117/12.2254676. Epub 2017 Mar 3 |
Language: | eng |
DOI/URL: |
101351R |
Notes: | LR: 20181113; GR: R21 CA178455/CA/NCI NIH HHS/United States; JID: 101524122; NIHMS867570; OTO: NOTNLM; 2017/07/11 06:00 [entrez]; 2017/07/12 06:00 [pubmed]; 2017/07/12 06:01 [medline]; ppublish |