Frequency of Large Intrafractional Target Motions during Spine Stereotactic Body Radiation Therapy

Publication date: Available online 22 August 2019Source: Practical Radiation OncologyAuthor(s): Jacqueline Wu, Josephine Wu, Åse Ballangrud, Jim Mechalakos, Josh Yamada, D. Michael LovelockAbstractSpine stereotactic body radiation therapy frequently involves the delivery of high doses to targets in proximity to the spinal cord, thus the radiation must be delivered with great spatial accuracy. Monitoring for large shifts in target and cord position that might occur during dose delivery is a challenge for clinics equipped with a conventional C-arm Linac. Treatment must be halted, then imaging and registration done to determine if a significant shift has occurred. In this retrospective study of 1019 spine SBRT treatments, we investigated the number target shifts> 2 mm in any direction that occurred in carefully immobilized patients. Orthogonal KV images were acquired 3 to 5 times during each session using in an in-room imaging system. Although the likelihood of large intrafractional shifts was found to be very low, they did occur in 6 treatment sessions. Intrafractional monitoring was found to be an important safety component of treatment delivery.
Source: Practical Radiation Oncology - Category: Cancer & Oncology Source Type: research