Wu J, Wu J, Ballangrud Å, Mechalakos J, Yamada J, Lovelock DM. Frequency of Large Intrafractional Target Motions During Spine Stereotactic Body Radiation Therapy.
Pract Radiat Oncol 2019;
10:e45-e49. [PMID:
31446148 DOI:
10.1016/j.prro.2019.08.006]
[Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 07/23/2019] [Accepted: 08/15/2019] [Indexed: 11/25/2022]
Abstract
Spine 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 must be done to determine whether a significant shift has occurred. In this retrospective study of 1019 spine SBRT treatments, we investigated the number of 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.
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