Three-dimensional Cherenkov emission surface mapping into the patient coordinate system for spatial delivery...

Area of Science:

• Medical Physics
• Optical Imaging
• Radiation Oncology

Background:

• Cherenkov imaging visualizes radiation therapy beam delivery in real-time.
• Current methods lack quantitative spatial registration, limiting deviation assessment.
• Qualitative assessments rely on manual checks, introducing potential errors.

Purpose of the Study:

• To develop a system for quantitative spatial beam verification using Cherenkov imaging.
• To enable objective measurement of beam delivery deviations in patient coordinate space.
• To establish automated error detection thresholds for real-time treatment verification.

Main Methods:

• Fusing multi-view Cherenkov images with CT-derived 3D patient surfaces.
• Utilizing a raycasting algorithm to create virtual beam's eye view (vBEV) images.
• Employing Iterative Closest Point (ICP) and Hausdorff distance for quantitative deviation measurement.

Main Results:

• Achieved high accuracy in measuring beam shifts on both flat and anthropomorphic phantoms (sub-millimeter precision).
• ICP algorithm demonstrated average accuracies of 0.5 mm (x) and 0.3 mm (y).
• Total system error, including camera projection, was approximately 0.9 mm.

Conclusions:

• Multi-view Cherenkov surface mapping enables quantitative assessment of beam shifts.
• The Cherenkov emission outline serves as a surrogate for beam extent.
• This approach paves the way for real-time, quantitative optical treatment verification using daily surface data.