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Published on: December 16, 2010
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Design of a compacted-sized eye-tracking system with indexed gaze target for ring gantry linear accelerators:
Queenie T K Shea1, April M K Chow1, W K Wong1
1Medical Physics Division, Department of Medical Innovation & Technology, CUHK Medical Centre, Shatin, Hong Kong SAR, People's Republic of China.
Biomedical Physics & Engineering Express
|March 5, 2025
Summary
This study introduces a compact eye-tracking system with a gaze target for precise ocular radiation therapy. The system offers accurate repositioning and interchangeable gaze targets, improving treatment delivery.
Area of Science:
- Medical Physics
- Ophthalmology
- Radiation Oncology
Background:
- Eye-tracking systems and gaze targets are crucial for immobilizing the eye during ocular radiation therapy.
- Existing systems may lack compactness or ease of setup in specialized treatment machines like ring gantry LINACs.
Purpose of the Study:
- To propose and evaluate a compact eye-tracking system with an integrated, interchangeable gaze target for ring gantry LINACs.
- To ensure accurate repositioning and reliable eye movement detection for enhanced treatment precision.
Main Methods:
- A compact camera was mounted on a 3D-printed stand with an indexed-positioning gaze target.
- Repositioning accuracy was assessed using Computed Tomography (CT) scans.
- Iris center detection and 3D displacement calculation were performed using fast radial symmetry transform and spherical eye globe rotation approximation.
Main Results:
- Mean repositioning errors for the camera and gaze target were 0.18 mm and 0.31 mm, respectively.
- Largest absolute error in iris center detection was 0.08 mm at 200 mm distance.
- Mean absolute error was below one pixel resolution, demonstrating high detection accuracy.
Conclusions:
- A compact, reproducible eye-tracking system with an interchangeable gaze target was successfully developed.
- The system enables accurate conversion of 2D iris motion to 3D displacement, allowing precise tolerance assessment of gaze direction.
