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Updated: May 3, 2026
Dynamic Lung Tumor Tracking for Stereotactic Ablative Body Radiation Therapy
Published on: June 7, 2015
A limited-angle intrafraction verification (LIVE) system for radiation therapy.
Lei Ren1, You Zhang2, Fang-Fang Yin1
1Department of Radiation Oncology, Duke University Medical Center, DUMC Box 3295, Durham, North Carolina 27710 and Medical Physics Graduate Program, Duke University, 2424 Erwin Road, Suite 101, Durham, North Carolina 27705.
The new Limited-Angle Intrafraction Verification (LIVE) system improves 3D/4D tumor localization accuracy during radiation therapy. This advancement enhances precision for stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) by verifying target position intrafractionally.
Area of Science:
- Medical Imaging
- Radiation Oncology
- Image-Guided Therapy
Background:
- Current 3D/4D volumetric x-ray imaging lacks intrafraction target verification capabilities, crucial for stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT).
- Precise intrafraction target localization is essential for minimizing treatment margins and enabling dose escalation in advanced radiation therapies.
Purpose of the Study:
- To develop and evaluate a Limited-Angle Intrafraction Verification (LIVE) system for intrafraction target position verification.
- To integrate prior information, deformation models, and limited-angle kV-MV projections for accurate real-time target tracking.
Main Methods:
- The LIVE system acquires simultaneous limited-angle kV and orthogonal MV projections during treatment delivery (arc or static beams).
- It utilizes prior CT scans, a breathing motion model (PCA), and a free-form deformation (FD) model to reconstruct the on-board patient volume.
- System performance was validated using 4D digital extended cardiac torso (XCAT) and CIRS dynamic thoracic phantoms, simulating realistic tumor motion and size changes.
Main Results:
- LIVE demonstrated superior reconstruction accuracy compared to using PCA or FD models alone in both phantom and simulation studies.
- With 30° scan angles, LIVE achieved average volume percentage difference (VPD) of 4.3% and center of mass (COM) difference of 0.3 mm in the XCAT phantom.
- In the CIRS phantom study, LIVE with 30° scan angles yielded VPD of 6.4% and COM difference of 1.4 mm, with accuracy decreasing at smaller scan angles (15°).
Conclusions:
- The LIVE system significantly enhances intrafraction target localization accuracy, offering volumetric verification during radiation delivery.
- This capability facilitates margin reduction and dose escalation in fractionated treatments, SRS, and SBRT.
- LIVE represents a novel approach for improving the precision and efficacy of image-guided radiation therapy.
