kVp, mA, and voxel size effect on 3D voxel-based superimposition

Area of Science:

• Radiology
• Medical Imaging
• Craniofacial Analysis

Background:

• Voxel-based superimposition is crucial for analyzing changes in the anterior cranial base.
• Cone beam computed tomography (CBCT) is widely used for craniofacial imaging.
• Optimizing CBCT parameters is essential for accurate superimposition.

Purpose of the Study:

• To evaluate how kilovoltage peak (kVp), milliamperage (mA), and voxel size affect the accuracy of voxel-based superimposition on the anterior cranial base.
• To determine the impact of specific CBCT imaging parameters on the reliability of 3D superimposition.
• To identify which imaging parameters most significantly influence superimposition accuracy.

Main Methods:

• CBCT scans of a phantom skull were acquired using varying kVp, mA, and voxel size settings.
• Scans were superimposed using commercial and open-source software.
• Three-dimensional (3D) color maps assessed differences in seven key craniofacial regions (Nasion, Point A, Zygomatic, Point B, Gonial).

Main Results:

• Lowering kVp resulted in the largest discrepancy (average 0.7 ± 0.3 mm), particularly in the Right Gonial region (1.4 ± 0.3 mm).
• Lowering mA showed a smaller average discrepancy (0.373 ± 0.2 mm), with a maximum of 0.7 ± 0.1 mm in the Right Gonial Area.
• Voxel size had the least impact, with mean discrepancies below 0.2 mm.

Conclusions:

• CBCT imaging parameters, especially low kVp, can influence the accuracy of voxel-based superimposition.
• Changes in mA and voxel size did not significantly alter the superimposition outcome.
• Careful selection of kVp is recommended to maintain the accuracy of craniofacial superimposition using CBCT.