Use of megavoltage cine-images for studying intra-thoracic motion during radiotherapy for locally advanced lung cancer

作者：Muirhead Rebecca^*; van der Weide Lineke; de Koste John R van Sornsen; Cover Keith S

来源：Radiotherapy and Oncology, 2011, 99(2): 155-160.

DOI：10.1016/j.radonc.2011.05.037

• Megavolt imaging
• Treatment verification
• Respiratory management
• 4-Dimensional CT scan
• Intra-fraction tumor motion

Background and purpose: Use of planning 4-dimensional CT (4DCT) scans often permits use of smaller target volumes for thoracic tumors but this assumes a reproducible pattern of motion during radiotherapy. We compared cranio-caudal (CC) motion on MV cine-images acquired during treatment with that seen on planning 4DCT.
Methods and materials: A pre-programmable respiratory motion phantom and a software tool for motion assessment were used to validate the use of MV cine-images for motion detection. MV cine-images acquired in 20 patients with node-positive lung cancer were analyzed using the same software. Intrafraction CC motion on 6 MV cine-images from each patient was compared with CC motion on their planning 4DCT.
Results: Software-based motion measurement on MV cine-images from the phantom corresponded to actual motion. Mean CC motion of primary tumor, carina and hilus on 4DCT was 7.3 mm (range 2-13.8 mm), 6.8 mm (1.8-21.2) and 11.0 mm (4.2-15.1), respectively. Corresponding intra-fraction motion on MV cine was 4.1 mm (0.6-13.6 mm); 2.7 mm (0-10 mm) and 6.0 mm (1.8-14.4 mm), respectively. The tumor, hilus and carina could be tracked in 95%, 88% and 38% of the MV cine-images, respectively.
Conclusions: Intra-fraction motion can be reliably measured using MV-cine images from a phantom. Motion discrepancies identified on MV cine-images can identify patients in whom planning 4DCT scans are not representative.

• 出版日期2011-5