4DCT co-synchronized to real-time dynamic MRI.
(2019) The International Conference on the Use of Computers in Radiation Therapy — Location: Montréal, Canada (17.June.2019)
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- Abstract
- 4D CT is a reference image modality to design the radiotherapy treatment plan of moving tumours as liver or lung tumours encompassing the displacements due to the breathing cycles. The treatment plan could provide margins to take into account the incertitude due to this motion. Breathing cycles can vary very much between the planning phase, when the 4D CT is acquired, and the different delivery of the doses during the radiotherapy treatment. In the treatment room, the breathing cycle could be of a different amplitude and could encompass some irregularities, like spasms. Dynamic MR images acquisition is becoming available in the treatment room in the case of photon-based radiotherapy through MR-Linac devices and will be one day available for protontherapy. Through these innovative technologies, the motion of organs due to breathing can be tracked in realtime to adapt the delivery and reduce margins. We propose in this paper a new approach which computes 4D CT sequences in real-time to be synchronized on the dynamic MRI. To achieve this synchronization in a controllable and reliable way, we associate each phase of an initial respiratory cycle of the 4D CT, including the inhale and exhale phases, to organ interfaces in the coronal plane of the sequence. The corresponding interfaces are also pointed in the dynamic MRI sequence. Through these marked interfaces the quality of the synchronization can be validated by the practitioner. The current position of the interfaces in the real-time MRI allows to compute the corresponding phase in the 4D CT sequence. For each MR image a 3D CT image is interpolated to generate a 4D CT on which the treatment plan can be shaped. To achieve the organ interfaces inter-modality synchronization, we have developed a new method based on the Otsu algorithm.
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Citations
Dasnoy-Sumell, D., & et al. (2019). 4DCT co-synchronized to real-time dynamic MRI. The International Conference on the Use of Computers in Radiation Therapy, Montréal, Canada. https://hdl.handle.net/2078.5/268927