Actuator-Assisted Calibration of Freehand 3D Ultrasound System

Table 4

Comparison of distance reconstruction accuracy among calibration approaches.

	Freehand cross wire	Actuator assisted cross wire	Actuator assisted collinear point targets	Actuator assisted modified collinear point targets	Acutator assisted cross wire (central region only)
Mean (SD)	0.19 (0.47)	0.19 (0.46)	0.21 (0.48)	0.21 (0.48)	0.244 (0.74)
Maximum	1.88	1.79	1.90	1.82	4.70
Minimum	−1.62	−1.64	−1.61	−1.56	−2.37

For each approach, point reconstruction precision was calculated from 25,000 observations. All data in mm. One-way ANOVA revealed a significant difference among calibration approaches. Post hoc analysis further revealed that if actuator-assisted cross wire phantom calibration was only focused on the central region, distance reconstruction accuracy was significantly poorer than the traditional freehand cross wire phantom calibration (). Other actuator-based calibration approaches were not significantly different from the traditional freehand cross wire phantom calibration.