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Stereotactic Cone-Beam CT Guided Radiosurgery of Trigeminal Neuralgia

B Ziemer , Y Natsuaki , A Perez-Andujar , O Morin , B Weethee , L Ma*, UCSF School of Medicine, San Francisco, CA 94143


(Sunday, 7/14/2019)  

Room: ePoster Forums

Purpose: Stereotactic cone-beam CT (sCBCT) produces voxel-by-voxel mapping of stereotactic coordinates within a volume of interest. In this study, we investigated the feasibility of replacing frame-based localization with online sCBCT guidance for Gamma Knife radiosurgery of trigeminal neuralgia.

Methods: For pre-treatment quality assurance checks, a 3D grid phantom with known stereotactic coordinates was scanned with sCBCT. Both stereotactic MR scans and sCBCT scans were performed for the treatment. MR-compatible fiducial markers were placed on the patient’s forehead. Stereotactic coordinates of these surface markers, internal anatomical checkpoints as well as embedded landmarks in the MR localization box were identified on the patient’s stereotactic MR scans, and then compared with those mapped with the sCBCT scans. Residual localization error based on the physical size of the localization box were determined for both sCBCT and stereotactic MR scans.

Results: The maximum discrepancy in the phantom stereotactic coordinates from the sCBCT scans versus pre-determined values was < 0.3 mm (mean: 0.12±0.08 mm). The surface and patient’s anatomical landmarks on the stereotactic MR scans and the same landmarks mapped with sCBCT scans agreed within 0.78±0.31 mm. Residual definition error was 0.31±0.10 mm for the sCBCT scans versus 0.66±0.23 mm for the stereotactic MR scans. Less than 0.7 mm shift in the maximum dose point was detected between frame-based and sCBCT-based localization.

Conclusion: The accuracy of sCBCT-based localization exceeded that of frame-based localization with MR-only imaging. sCBCT-guided radiosurgery of trigeminal neuralgia is demonstrated to be safe and practical.


Cone-beam CT, Radiosurgery, Localization


TH- External beam- photons: intracranial stereotactic/SBRT

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