An MRI-based mid-ventilation approach for radiotherapy of the liver.

An MRI-based mid-ventilation approach for radiotherapy of the liver. Radiother Oncol. 2016 Nov 5;: Authors: van de Lindt TN, Schubert G, van der Heide UA, Sonke JJ Abstract MRI is increasingly being used in radiotherapy of the liver. The purpose of this study was to develop and validate a strategy to acquire MR images for treatment planning and image guidance in the presence of respiratory motion. By interleaving two navigator triggered MRI sequences, a fast but low-resolution image in mid-ventilation (midV) and a high-resolution image in exhale were acquired efficiently. Deformable registration was applied to map the exhale image to the midV anatomy. Cine-MRI scans were acquired for motion quantification. The method was validated with a motion phantom, 10 volunteers and 1 patient with a liver tumor. The time-weighted mean position of a local structure in a cine-scan was defined as the midV-position ground truth and used to determine the accuracy of the midV-triggering method. Deformable registration accuracy was validated using the SIFT algorithm. Acquisition time of the midV/exhale-scan was 3-5min. The accuracy of the midV-position was ⩽0.5±0.5mm for phantom motion and ⩽0.9±1.2mm for the volunteers. Mean residuals after deformable registration were ⩽0.2±1.8mm. The accuracy and reproducibility of the method are within inter- and intra-fraction liver position variability (Case et al., 2009) and could in the future be incorpo...
Source: Radiotherapy and Oncology : journal of the European Society for Therapeutic Radiology and Oncology - Category: Radiology Authors: Tags: Radiother Oncol Source Type: research