AUTHOR=Kang Chen-Lin , Liu Shyh-Chang , Wang Jui-Chu , Liao Kuan-Cho , Huang Yu-Jie , Fang Fu-Min , Liao Tsung-I , Juan Kuo-Jung , Huang Chun-Chieh
TITLE=Comparison of Skull Motions in Six Degrees of Freedom Between Two Head Supports During Frameless Radiosurgery by CyberKnife
JOURNAL=Frontiers in Oncology
VOLUME=8
YEAR=2018
URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2018.00359
DOI=10.3389/fonc.2018.00359
ISSN=2234-943X
ABSTRACT=Introduction: Maintaining immobilization to minimize skull motion is important during frameless radiosurgery. This study aimed to compare the intrafractional skull motions between two head supports.
Methods: With 6D skull tracking system, 4,075 image records from 45 patients receiving radiosurgery by CyberKnife were obtained. Twenty-three patients used TIMO head supports (CIVCO) (Group A) and twenty-two patients used Silverman head supports (CIVCO) with MoldCare cushions (ALCARE) (Group B). The skull motions in X (superior-inferior), Y (right-left), Z (anterior-posterior) axes, 3D (three-dimensional) vector, Roll, Pitch and Yaw between the two groups were compared and the margins of planning target volume were estimated.
Results: The translational motions in Group A were similar in three axes at initial but became different after 10 min, and those in Group B were less prominent in the Y axis. The rotational errors in Group A were most obvious in Yaw, but those in Group B were stationary in three axes. The motions in the X axis, 3D vector, Pitch and Yaw in Group B were significantly smaller than those in Group A; conversely, the motions in the Z axis in Group B were larger. To cover the 95% confidence intervals, margins of 0.77, 0.79, and 0.40 mm in the X, Y, and Z axes, respectively, were needed in Group A, and 0.69, 0.50, and 0.51 mm were needed in Group B.
Conclusions: Both head supports could provide good immobilization during the frameless radiosurgery. Silverman head support with MoldCare cushion was better than TIMO head support in the superior-inferior direction, 3D vector, Pitch and Yaw axes, but worse in the anterior-posterior direction.