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Dynamic Lung Tumor Tracking for Stereotactic Ablative Body Radiation Therapy
Published on: June 7, 2015
Accuracy estimation for projection-to-volume targeting during rotational therapy: a feasibility study
Yong Long1, Jeffrey A Fessler, James M Balter
1Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109-2122, USA. yonglong@umich.edu
Medical Physics
|July 17, 2010
Summary
Accurate tumor motion estimation during arc therapy is possible even with limited projection data. Rotational arc length influences accuracy, but sufficient information exists for monitoring tumors without markers.
Area of Science:
- Medical Physics
- Radiotherapy
- Image-guided therapy
Background:
- Accurate tumor targeting in arc therapy relies on estimating motion and deformation from projection radiographs.
- A reference CT volume is used for alignment, making motion estimation a promising technique.
Purpose of the Study:
- To investigate how rotational arc length affects the maximum achievable accuracy of motion estimation.
- To assess the feasibility of monitoring tumor configuration using limited projection data.
Main Methods:
- A nonrigid model was used for thorax motion, with a cost function based on least-squared error and local invertibility regularization.
- A four-level multiresolution scheme and conjugate gradient method optimized the cost function.
- Limited-angle scans with varying angular widths and centers were tested with small and large deformations.
Main Results:
- Limited-angle projection-to-volume alignment demonstrated potential accuracy.
- Registration accuracy was sensitive to angular center and decreased with distance from the rotation center.
- Trends showed low sensitivity to quantum noise effects.
Conclusions:
- Sufficient information in limited projection spreads can monitor high-contrast tumors without implanted markers.
- This technique offers a promising avenue for image-guided radiotherapy.
