Encrypted login | home

Program Information

Assessment of Intrafraction Motion During Cranial Radiosurgery

M Lamba

M Lamba*, D Go , R Warnick , J Breneman , University of Cincinnati, Cincinnati, OH


SU-I-GPD-J-7 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: To retrospectively review radiosurgery alignment films, assess intrafraction motion, and investigate the dose effects of intra-fraction patient motion for the subset of patients with motion greater than 1mm in at least one direction during image-guided cranial radiosurgery.

Methods: Patient 3D alignment data (initial, 2-5 during and at completion) was collected using 1016 consecutive radiographs for single or five fraction radiosurgery treatments. For those radiographs indicating a shift of greater than 1 mm in at least one direction an automated script was used to shift the treatment as delivered and then analyzed based on standard radiosurgery plan metrics. 

Results: 73 patients received a total 270 radiosurgery treatments. 3D mean error between initial alignment and subsequent films was 0.4 mm 0.3 mm.  2.5% of shifts were greater than 1 mm, and 0.2% greater than 2 mm. 8 lesions treated had errors greater than 1 mm in at least one direction. For 7 out of the 8 cases, intra-fraction motion changed conformality index by less than 5%. In one case 75% of the delivered treatment was altered by intra-fraction motion with a 3D magnitude value of 1.86 mm for a single fraction treatment resulting in significant change in radiosurgery metrics. Five fraction radiosurgery treatments were found to be very robust to intrafraction motion. Of the 8 patients, one patient died before follow-up imaging, one patient experienced an adverse event of radiation necrosis, with the balance achieving partial or complete responses.

Conclusion: Clinically relevant intra-fraction motion during image-guided cranial radiosurgery was evaluated for all patients during an approximately one-year period.  2.5% of intrafraction shifts were greater than 1 mm, and 0.2% greater than 2 mm. Radiosurgery metrics of treatment plans were not significantly altered by intrafraction motion in 7 of 8 lesions with motion greater than 1 mm in at least one direction.

Contact Email: