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Surface Imaging Accuracy for Stereotactic Radiosurgery Setup and Treatment Delivery

J McCulloch*, V Bry , D Saenz , P Myers , N Kirby , K Rasmussen , UTHSCSA, San Antonio, TX


(Saturday, 3/30/2019)  

Room: Exhibit Hall

Purpose: To determine the accuracy of using the C-RAD Catalyst HD surface imaging system for Stereotactic Radiosurgery treatment setup.

Methods: An anthropomorphic head phantom was imaged on a GE LightSpeed CT scanner in a head-first supine SRS treatment position. Plans were created with couch angles at 270, 225, 180, 135, and 90 degrees in the BrainLab treatment planning software with a simulated lesion in the right frontal lobe and the left occipital lobe. White tape was placed on the phantom’s exterior in order to make it more visible to the Catalyst HD’s cameras. The phantom was set up at the 180 degrees using Brainlab ExacTrac. The coordinates were captured with the C-Rad Catalyst HD system. The phantom was then set up at each of the different couch positions with ExacTrac x-ray imaging to verify internal anatomy accuracy. At each position the Brainlab shifts to isocenter were compared with the C-Rad shifts to isocenter in each dimension.

Results: External surface imaging and internal x-ray imaging had agreement within 0.62 mm, 0.84 mm, and 0.60 mm in the vertical, lateral, and longitudinal dimensions respectively across all couch angles. Total range of values for each were 0.02 mm – 0.62 mm, 0.01 mm – 0.84 mm, and 0.01 mm – 0.60 mm respectively. The maximal vector shifts were calculated to be ranging from 0.11 mm – 1.05 mm. Rotation deviation was negligible for all angles (<0.2˚).

Conclusion: For the phantom analyzed, C-RAD Catalyst HD has a discrepancy of less than 1 mm from internal x-ray imaging in each cardinal direction for the full range of couch angles. These results are promising for its application for SRS treatment and verification.

Funding Support, Disclosures, and Conflict of Interest: Research funded in part by a vendor grant.


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