Related Experiment Video
Updated: Mar 21, 2026
Stereotactic Radiosurgery for Gynecologic Cancer
Published on: April 17, 2012
Technical Note: Evaluation of the systematic accuracy of a frameless, multiple image modality guided, linear
N Wen1, K C Snyder1, S G Scheib2
1Department of Radiation Oncology, Henry Ford Health System, 2799 West Brand Boulevard, Detroit, Michigan 48202.
Purpose:
To evaluate the total systematic accuracy of a frameless, image guided stereotactic radiosurgery system.
Methods:
The localization accuracy and intermodality difference was determined by delivering radiation to an end-to-end prototype phantom, in which the targets were localized using optical surface monitoring system (OSMS), electromagnetic beacon-based tracking (Calypso®), cone-beam CT, "snap-shot" planar x-ray imaging, and a robotic couch. Six IMRT plans with jaw tracking and a flattening filter free beam were used to study the dosimetric accuracy for intracranial and spinal stereotactic radiosurgery treatment.
Results:
End-to-end localization accuracy of the system evaluated with the end-to-end phantom was 0.5 ± 0.2 mm with a maximum deviation of 0.9 mm over 90 measurements (including jaw, MLC, and cone measurements for both auto and manual fusion) for single isocenter, single target treatment, 0.6 ± 0.4 mm for multitarget treatment with shared isocenter. Residual setup errors were within 0.1 mm for OSMS, and 0.3 mm for Calypso. Dosimetric evaluation based on absolute film dosimetry showed greater than 90% pass rate for all cases using a gamma criteria of 3%/1 mm.
Conclusions:
The authors' experience demonstrates that the localization accuracy of the frameless image-guided system is comparable to robotic or invasive frame based radiosurgery systems.
