Perspective pinhole model with planar source for augmented reality surgical navigation based on C-arm imaging

Area of Science:

• Medical Imaging
• Computer-Aided Surgery
• Surgical Navigation

Background:

• Augmented reality (AR) surgical navigation relies on accurate overlay of virtual information onto C-arm X-ray images.
• Conventional pinhole camera models used for C-arm calibration introduce overlay displacement, compromising navigation accuracy.
• This displacement is particularly problematic for 3D objects and varies with depth.

Purpose of the Study:

• To propose and validate a modified C-arm calibration model to reduce overlay displacement in AR surgical navigation.
• To enhance the accuracy of AR overlays on X-ray images for improved surgical guidance.

Main Methods:

• Analyzed displacement patterns of 3D objects in C-arm imaging.
• Modeled X-ray source movement as variable intrinsic parameters, replacing the point source with a planar source.
• Implemented a modified pinhole model incorporating the planar source concept.

Main Results:

• The proposed planar source model significantly reduced overlay displacement compared to the conventional method.
• Achieved more accurate spatial and depth overlay of AR onto X-ray images.
• Validated the reduction of displacement and its independence from object depth.

Conclusions:

• Intrinsic parameters describing X-ray source position are depth-dependent for 3D objects.
• The proposed planar source model effectively reduces overlay displacement in C-arm calibration.
• This advancement is essential for enhancing the precision of augmented reality surgical navigation systems.