The study aims to evaluate the imaging and positioning accuracy of the BrainLab ExacTrac Dynamic System integrated with the Varian TrueBeam Linear Accelerator for stereotactic radiotherapy.
METHODS
BrainLab ExacTrac Dynamic System, BrainLab Phantom Pointer, and BrainLab Head Phantom were
utilized. Imaging and positioning accuracy were assessed through manual and couch-induced displacement
tests. This article does not contain any studies with human participants or animals performed
by any of the authors. Ethical approval was not required for this study as it was conducted
using phantoms only.
RESULTS
The study evaluated the accuracy of BrainLab ETD and Varian cone-beam computed tomography
(CBCT) systems using a shared reference. Both systems demonstrated sub-millimeter precision, with
translational errors ranging between 0.06 mm (ETD Z-axis) and 0.04 mm (ETD X-axis), and rotational
errors below 0.12°. Maximum observed errors did not exceed 0.3 mm for translational or
0.2° for rotational movements. For combined errors 3D translational accuracy showed no significant
difference p=0.482) between ETD (0.11 mm) and CBCT (0.09 mm). The 6D error magnitude was
slightly lower for ETD (0.14 mm vs. 0.20 mm, p<0.001). Correlation analysis revealed that single-axis
correlations between ETD and CBCT were not significant (p>0.05) except for pitch errors (p=0.023),
which showed moderate correlation. The mean DIFF 6D vector (0.23 mm), representing the positional
offset between ETD and CBCT detections, was significantly larger than both ETD 6D and CBCT
6D errors (p<0.001 and p=0.002, respectively).
CONCLUSION
Both systems offer high precision in detecting positional shifts. The ETD System"s ability to provide continuous,
real-time monitoring enhances patient safety by allowing real-time correction of positioning
errors, making it a valuable tool for stereotactic radiotherapy applications. Further studies with patient
data are needed to validate the clinical application of these findings.