Position and Orientation Errors in a Neuronavigation Procedure: A Stepwise Protocol Using a Cranial Phantom.


Department of Neurosurgery, Hospital de Santa Maria, CHLN, Lisbon, Portugal. Electronic address: [Email]


OBJECTIVE : Neuronavigation procedures demand high precision and accuracy. Despite this need, there are still few studies analyzing errors in such procedures. The aim of this study was to use a custom-built cranial phantom to measure target position and orientation errors in different phases of a simulated neuronavigation procedure.
METHODS : A cranial phantom with 10 target sites was designed and imaged with computed tomography and magnetic resonance. A segmentation of a cloud of points of the phantom (ground truth) was obtained using an optical tracking system and compared with the images (imaging phase). Targets and trajectories were then planned with neuronavigation software and compared with the ground truth (planning phase). The same plan was used to identify the points in real space after image-to-phantom registration and calculate the final error of the procedure by comparison with the ground truth (registration and execution phase).
RESULTS : The mean errors after the imaging phase were 1.11 ± 0.42 mm and 3.23° ± 1.69° for position and orientation, respectively. After planning the mean errors were 1.10 ± 0.39 mm and 5.55° ± 2.91°. The global errors after the registration and mechanical execution were 3.93 ± 1.70 mm and 3.65° ± 1.29°.
CONCLUSIONS : After a stepwise analysis, registration and mechanical execution were the main contributors to the global position error.


Accuracy,Error analysis,Image-guided neurosurgery,Neuronavigation,Phantom,Precision,

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