title: Intrafractional setup errors in patients undergoing non-invasive fixation using an immobilization system during hypofractionated stereotactic radiotherapy for lung tumors.
abstract: Intrafractional setup errors during hypofractionated stereotactic radiotherapy (SRT) were investigated on the patient under voluntary breath-holding conditions with non-invasive immobilization on the CT-linac treatment table. A total of 30 patients with primary and metastatic lung tumors were treated with the hypofractionated SRT with a total dose of 48-60 Gy with four treatment fractions. The patient was placed supine and stabilized on the table with non-invasive patient fixation. Intrafractional setup errors in Right/Left (R.L.), Posterior/Anterior (P.A.), and Inferior/Superior (I.S.) dimensions were analyzed with pre- and post-irradiation CT images. The means and one standard deviation of the intrafractional errors were 0.9 ± 0.7mm (R.L.), 0.9 ± 0.7mm (P.A.) and 0.5 ± 1.0 mm (I.S.). Setup errors in each session of the treatment demonstrated no statistically significant difference in the mean value between any two sessions. The frequency within 3mm displacement was 98% in R.L., 98% in P.A. and 97% in I.S. directions. SRT under the non-invasive patient fixation immobilization system with a comparatively loose vacuum pillow demonstrated satisfactory reproducibility of minimal setup errors with voluntary breath-holding conditions that required a small internal margin.
authors: Department of Radiation Oncology, University of Yamanashi, 1110, Chuo-city, Yamanashi 409-3898, Japan. meguruw@gmail.com
authors: Meguru
authors: M
authors: Watanabe
authors: Hiroshi
authors: H
authors: Onishi
authors: Kengo
authors: K
authors: Kuriyama
authors: Takafumi
authors: T
authors: Komiyama
authors: Kan
authors: K
authors: Marino
authors: Masayuki
authors: M
authors: Araya
authors: Ryo
authors: R
authors: Saito
authors: Shinichi
authors: S
authors: Aoki
authors: Yoshiyasu
authors: Y
authors: Maehata
authors: Rihito
authors: R
authors: Tominaga
authors: Jitsuhiko
authors: J
authors: Oguri
authors: Naoki
authors: N
authors: Sano
authors: Tsutomu
authors: T
authors: Araki
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003198:Computer Simulation; D019583:Dose Fractionation, Radiation; D004867:Equipment Design; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D007103:Immobilization / Q000379:methods*; D008175:Lung Neoplasms / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D016634:Radiosurgery / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012119:Respiration; D012189:Retrospective Studies; D016896:Treatment Outcome
keywords: hypofractionated stereotactic radiotherapy; intrafractional setup errors; lung cancers; non-invasive patient fixation immobilization