RealMove (Lung): Assessing Tumour Motion With Dynamic MRI

The study aims to develop an improved method to tailor the geometric safety margin when treating with stereotactic body radiotherapy (SBRT), to avoid tumour cells being missed during irradiation and to limit the exposure of normal tissues as much as possible. Dynamic magnetic resonance imaging (MRI) is assumed to represent the tumour motion during the respiratory cycle more realistically, compared to 4-dimensional computed tomography (4D CT), thanks to its high temporal resolution and the possibility to image the motion over a longer period of time. Patients receiving SBRT for a pulmonary target located below the level of the carina are included in the study, and the hypothesis will be tested through a comparison of the tumour amplitude measured with each modality. Furthermore, the predictive value of the image series acquired at treatment planning, for the motion patterns observed at each treatment fraction, will be evaluated through repeated 4D CBCT acquisitions.