title: Influence of respiration on dose calculation in stereotactic body radiotherapy of the lung.
abstract: Our purpose in this study was to evaluate the variation in calculated doses caused by respiration in stereotactic body radiotherapy (SBRT) of the lung. The study targeted ten patients who underwent SBRT for lung tumors. CT images were acquired during free breathing and in the inhalation and exhalation phases. We compared the CT image at inhalation with the image at exhalation so as to measure the change in lung volume, variation in the CT value, and displacement of the chest wall. The lung volume change was shown to be correlated with the maximum of the chest wall motion and with the variation in the CT value. A statistically significant difference was observed in the CT values between inhalation and exhalation (p < 0.05). The total dose variation at the isocenter was confined within ±2 %. However, the dose from individual beams can vary significantly when the chest wall moves more than 10 mm in natural breathing.
authors.affiliation: Graduate School of Health Sciences, Hokkaido University, Kita-12, Nishi-5, Kita-ku, Sapporo, 060-0812, Japan.
authors.forename: Rie
authors.initials: R
authors.lastname: Yamazaki
authors.forename: Rikiya
authors.initials: R
authors.lastname: Onimaru
authors.forename: Norio
authors.initials: N
authors.lastname: Katoh
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Inoue
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nishioka
authors.forename: Hiroki
authors.initials: H
authors.lastname: Shirato
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Date
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery*; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology / Q000532:radiotherapy; D008297:Male; D008875:Middle Aged; D009068:Movement; D009929:Organ Size; D011829:Radiation Dosage; D016634:Radiosurgery / Q000379:methods*; D012119:Respiration; D014057:Tomography, X-Ray Computed