Abstract:
This study establishes a novel high-resolution fast magnetic resonance imaging(MRI) method that incorporates Beam Eye View(BEV) and Beam Path View(BPV) fusion information. Three liver metastasis patients undergoing MRI guided radiotherapy(MRgRT) were selected. A total of 31 200 frames of MRI images were acquired from each patient using two motion patterns: restricted abdominal motion using an abdominal compression belt(RAM group) and free breathing(FB group). Tumor tracking was performed using nearby vessels with clear boundaries, and the radial vector motion amplitude difference(∆R95) within the 95% confidence interval was calculated. The differences in ΔR95 between the RAM and FB groups in all fractions on the BEV/BPV plane were as follows: for Patient 1, they were all less than 0.58 mm; for Patient 2, they were greater than 2.57 mm; for Patient 3, they were 0.71 and 1.05 mm, respectively. The results indicate that the abdominal compression technique can effectively reduce tumor motion magnitude, and the tumor motion magnitude ΔR95 variation is highly individual-specific. This method can serve as an imaging basis for the tumor margin reduction in MRgRT.