The aim of this study is to compare intrafractional motion using two commercial non-invasive immobilization systems for linac-based intracranial stereotactic radiosurgery (SRS) under guidance with a surface-guided radiotherapy (SGRT) system.


 Real-time surface motion data in 37 treatment fractions using the vacuum fixation system and 44 fractions using the open-face mask were recorded by an SGRT system. 
SGRT
The aim of this study is to compare intrafractional motion using two commercial non-invasive immobilization systems for linac-based intracranial stereotactic radiosurgery (SRS) under guidance with a surface-guided radiotherapy (SGRT) system.



linac-based intracranial stereotactic radiosurgery
The aim of this study is to compare intrafractional motion using two commercial non-invasive immobilization systems for linac-based intracranial stereotactic radiosurgery (SRS) under guidance with a surface-guided radiotherapy (SGRT) system.



surface-guided radiotherapy (SGRT)
Ten patients were immobilized with a vacuum fixation biteplate system, while 11 patients were immobilized with an open-face mask system. 
vacuum fixation biteplate system
Ten patients were immobilized with a vacuum fixation biteplate system, while 11 patients were immobilized with an open-face mask system.  Using the vacuum fixation system, the average and standard deviations of the shifts were 0.01 ± 0.18 mm, -0.06 ± 0.30 mm, and  0.02 ± 0.26 mm in the anterior-posterior (AP), superior-inferior (SI), and left-right (LR) directions, and -0.02 ± 0.19°, -0.01 ± 0.13°, and 0.01 ± 0.13° for rotations in yaw, roll, and pitch, respectively; using the open-face mask system, the average and standard deviations of the shifts were -0.06 ± 0.20 mm, -0.02 ± 0.35 mm, and 0.01 ± 0.40 mm in the AP, SI, and LR directions, and were 0.05 ± 0.23°, 0.02 ± 0.21°, and 0.00 ± 0.16° for rotations in yaw, roll, and pitch, respectively.  Patients with the vacuum fixation system had significantly smaller intrafractional motion variation compared to those with the open-face mask system. 
open-face mask system