Effect of residual patient motion on dose distribution during image-guided robotic radiosurgery for skull tracking based on log file analysis.
OBJECTIVE
The present study aimed to assess the effect of residual patient motion on dose distribution during intracranial image-guided robotic radiosurgery by analyzing the system log files.


METHODS
The dosimetric effect was analyzed according to the difference between the original and estimated dose distributions, including targeting error, caused by residual patient motion between two successive image acquisitions. One hundred twenty-eight treatments were analyzed. Forty-two patients were treated using the isocentric plan, and 86 patients were treated using the conformal (non-isocentric) plan.


RESULTS
The median distance from the imaging center to the target was 55 mm, and the median interval between the acquisitions of sequential images was 79 s. The median translational residual patient motion was 0.1 mm for each axis, and the rotational residual patient motion was 0.1° for Δpitch and Δroll and 0.2° for Δyaw. The dose error for D 95 was within 1 % in more than 95 % of cases. The maximum dose error for D 10 to D 90 was within 2 %. None of the studied parameters, including the interval between the acquisitions of sequential images, was significantly related to the dosimetric effect.


CONCLUSIONS
The effect of residual patient motion on dose distribution was minimal.
Department of Quality Management with Radiotherapy, Yokohama CyberKnife Center, Shinryoku Neurosurgical Clinic, 574-1 Ichisawa-cho, Asahi-ku, Yokohama, 241-0014, Japan, m-inoue@syck.jp.
Mitsuhiro
M
Inoue
Hiroya
H
Shiomi
Kengo
K
Sato
Junichi
J
Taguchi
Kohei
K
Okawa
Kosaku
K
Inada
Taro
T
Murai
Izumi
I
Koike
Koshi
K
Tatewaki
Seiji
S
Ota
Tomio
T
Inoue
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000601:surgery*; D002648:Child; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D008875:Middle Aged; D009068:Movement; D011829:Radiation Dosage; D015641:Radiography, Interventional / Q000379:methods*; D016634:Radiosurgery / Q000379:methods*; D012371:Robotics / Q000379:methods*; D012886:Skull; D014057:Tomography, X-Ray Computed / Q000379:methods; D055815:Young Adult