Three-dimensional MRI-linac intra-fraction guidance using multiple orthogonal cine-MRI planes

Phys Med Biol. 2013 Jul 21;58(14):4943-50. doi: 10.1088/0031-9155/58/14/4943. Epub 2013 Jun 27.


The introduction of integrated MRI-radiation therapy systems will offer live intra-fraction imaging. We propose a feasible low-latency multi-plane MRI-linac guidance strategy. In this work we demonstrate how interleaved acquired, orthogonal cine-MRI planes can be used for low-latency tracking of the 3D trajectory of a soft-tissue target structure. The proposed strategy relies on acquiring a pre-treatment 3D breath-hold scan, extracting a 3D target template and performing template matching between this 3D template and pairs of orthogonal 2D cine-MRI planes intersecting the target motion path. For a 60 s free-breathing series of orthogonal cine-MRI planes, we demonstrate that the method was capable of accurately tracking the respiration related 3D motion of the left kidney. Quantitative evaluation of the method using a dataset designed for this purpose revealed a translational error of 1.15 mm for a translation of 39.9 mm. We have demonstrated how interleaved acquired, orthogonal cine-MRI planes can be used for online tracking of soft-tissue target volumes.

MeSH terms

  • Dose Fractionation, Radiation*
  • Feasibility Studies
  • Humans
  • Imaging, Three-Dimensional / methods*
  • Magnetic Resonance Imaging / methods*
  • Movement
  • Radiotherapy, Image-Guided / methods*