Effect of fiducial configuration on target registration eerror in image-guided surgery-A experiment study

This paper investigates the effect of fiducials configuration on target registration error (TRE) and test the accuracy of theoretical model of TRE prediction in image-guided cranio-maxillofacial surgery. The skull specimen is prepared with 20 titanium microscrews placed at defined locations and scanned with a 64-slice spiral computed tomography unit. These markers are separated to registration fiducial group and target fiducial group. An optical tracking system is used to perform skull-to-image registration procedures. Subsequent to each registration, the TRE is calculated by the navigation system. Each configuration have been performed registration 50 times and the average is regarded as TRE of the configuration. The TRE prediction is also calculated for each configuration. The TRE ranges from 0.58mm to 3.88mm, relatively smaller values of TRE may be achieved by placing a majority of fiducials on the maxillary alveolus in proximity about the target and placing a small number on the cranium contralaterally. The TRE values are always larger than the corresponding TRE prediction but there is high correlation between them. The configuration of fiducials is an important factor in minimizing TRE and the TRE prediction is a good guidance for fiducial markers placement.