Evaluation of a calibration rig for stereo laparoscopes

Area of Science:

• Medical Imaging
• Surgical Technology
• Robotics

Background:

• Accurate camera and hand-eye calibration are crucial for image-guided surgery.
• Calibration methods must be user-friendly for non-experts in surgical settings.

Purpose of the Study:

• To identify an effective method for tracked stereo laparoscope calibration in an operating theater environment.

Main Methods:

• A custom calibration rig was designed for rapid, in-situ calibration.
• The rig's performance was evaluated against freehand calibration.
• Calibration quality was assessed using stereo reprojection and reconstruction error metrics.

Main Results:

• The calibration rig significantly reduced mean errors in reprojection (1.47 mm vs. 3.14 mm) and reconstruction (1.37 px vs. 10.10 px) compared to freehand methods.
• Tracked reconstruction errors were also substantially lower with the rig (1.38 mm vs. 12.64 mm).
• ChArUco patterns offered slightly better reprojection accuracy, while dot grids excelled in reconstruction accuracy and robustness to lighting.

Conclusions:

• The custom calibration rig offers a statistically significant reduction in calibration errors.
• The rig is the preferred method for operating theater use due to its improved accuracy and reliability.