The computed cranial focal point

Area of Science:

• Medical Imaging
• Craniomaxillofacial Surgery
• Biomedical Engineering

Background:

• Stereophotogrammetry offers radiation-free monitoring of skull development post-craniosynostosis repair.
• Establishing fixed reference points for longitudinal 3D photograph comparisons remains a challenge.
• The computed cranial focal point (CCFP) was developed to address this limitation.

Purpose of the Study:

• To introduce and validate the computed cranial focal point (CCFP) as a novel reference point.
• To assess the robustness of CCFP calculation using 3D CT scans.
• To demonstrate the utility of CCFP in correlating 3D photographic data with CT scans.

Main Methods:

• CCFP was calculated using Matlab on segmented 3D CT scans of 36 adult subjects.
• Robustness was evaluated using predefined hemi-ellipsoid shapes.
• CCFP was applied in two clinical cases to correlate CT and 3D photographic data.

Main Results:

• CCFP calculation showed minimal deviation (<2.5 mm) even with incomplete or deformed surface data.
• The average position of the skin CCFP relative to the sella turcica was determined.
• Mean differences between skull and skin CCFP were minimal, and clinical case correlations showed high accuracy (0.7-2.3 mm mean differences).

Conclusions:

• CCFP provides a robust method for defining a reference point on skin or bone surfaces relative to the sella turcica.
• CCFP facilitates accurate correlation between 3D photographs and CT scan data.
• This method enables reliable, radiation-free longitudinal comparisons of 3D skull photographs.