Room: Stars at Night Ballroom 4
Purpose: To predict the collision clearance distance of stereotactic cones with treatment setup devices in the cone-based Brainlab stereotactic radiosurgery (SRS) treatments.
Methods: A Brainlab Head & Neck Treatment System with a Frameless Radiosurgery Positioning Array was scanned with CT simulator. The outer body surface of the treatment table and array was contoured as a structure and exported in a DICOM format. An in-house software was developed to calculate the minimum clearance distance between the cone and the outer surface that determines the occurrence of the collision. The minimum clearance distance was calculated by translating the exported outer contours into Beamâ€™s Eye View (BEV) coordinates per planned arc range and couch angles. From the minimum clearance distance, the collision-free gantry ranges per each couch angle were sequentially determined. The software was extensively tested for various combinations of couch and arc angles at multiple isocenter locations using a Varian ICVI (Integrated Conical Collimator Verification & Interlock) stereotactic cone system. A total of 44 cases were used for the tests to validate the calculation accuracy of the software. Minimum distance and collision-free angles were physically measured respectively.
Results: The calculated minimum distances from the software was found to agree well with the measurements to within 2.0 Â± 4.0 mm for 22 arcs. Predicted collision-free arc angle also agreed well with the measurements with a 2-5 mm margin for 20 arcs.
Conclusion: The in-house software was able to calculate the minimum clearance distance and the collision-free arc range with a reasonable accuracy for cone-based Brainlab SRS. It will provide better prior knowledge for the arrangement of couch and arc angle in the cone-based SRS planning.