Background: Fiducial markers are frequently used before treatment for imageguided patient setup in radiation therapy (RT), but can also be used during treatment for image‐guided intrafraction motion detection. This report describes our implementation of automatic marker detection with periodic kV imaging (TrueBeam v2.5) to monitor and correct intrafraction motion during prostate RT.
Methods: We evaluated the reproducibility and accuracy of software fiducial detection using a phantom with 3 implanted [Gold Anchor] fiducial markers. Clinical implementation for patients with intraprostatic fiducials receiving volumetric modulated arc therapy (VMAT) utilized periodic on‐board kV imaging with 10 s intervals during treatment delivery. For each image, the software automatically identified fiducial locations and determined whether their distance relative to planned locations were within a 3 mm tolerance. Motion was corrected if either ≥2 fiducials in a single image or ≥1 fiducial in sequential images were out of tolerance.
Conclusion: Periodic kV imaging with automatic detection of motion during VMAT prostate treatments is commercially available and can be successfully implemented to mitigate effects of intrafraction motion with careful attention to software settings.
Article from Journal of Applied Clinical Medical Physics, 2020