Organ Motion from 4DMRI
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Applications of Motion Data

Proton Therapy Planning

By using intensity modulated radiotherapy (IMRT) and especially intensity modulated proton therapy (IMPT), highly conformal dose distributions can be delivered to a tumour. With the obtained motion data, different delivery methodologies are evaluated with respect to motion sensitivity in order to study the interaction between time-varying delivery and realistic respiratory motion.

animated liver surface resulting dose distribution
animate enlarge
A hypothetic tumour is animated according to the obtained motion data. A simple one-field proton therapy plan shows the effect of this motion on the dose distribution.

Although the reconstructed MR images cannot be used directly for dose calculations, the deformation vectors resulting from the motion estimation are independent of the imaging modality. These motion vectors can be used to deform planning CT images or the displacement vectors can be integrated directly into the dynamic dose calculation.

animated liver surface A CT volume was animated according to the motionfield determined from 4DMRI of the same patient.

Evaluation of Gating Methods

Potential gating techniques for radiation therapy and MRI guided Focused Ultrasound (MRgFUS), which are applicable in real-time, are currently being evaluated with respect to residual motion and optimal placement of surrogates.

motion (no gating) motion (amplitude gating)
Point positions without and with gating (30% duty cycle)

Training and Planning of RF Ablation

The obtained data will be used to build generic models of shape and motion of the liver. The models will be intregrated into a simulation environment for radiofrequency (RF) ablation of liver tumours.