title: Equivalent doses for gynecological patients undergoing IMRT or RapidArc with kilovoltage cone beam CT.
abstract: OBJECTIVE
  To investigate in-field and peripheral kilovoltage cone beam CT (CBCT) doses in gynecological patients in comparison with IMRT or RapidArc scatter and linac leakage doses.
  
  
  METHODS
  Monte Carlo codes BEAMnrc/DOSXYZnrc were used to simulate dose for daily use of kV CBCT in patients undergoing adjuvant pelvic radiotherapy for uterine or ovarian malignancies. Biological effectiveness was accounted for using a lineal energy based quality factor. Organ equivalent doses (OED) within the treatment field were modeled with linear-exponential, plateau and linear dose response curves. CBCT doses in peripheral regions were compared with IMRT and RapidArc scatter doses as well as linac leakage doses.
  
  
  RESULTS
  CBCT doses in peripheral regions were on the order of linac leakage doses and one order of magnitude lower than IMRT or RapidArc scatter doses. OEDs increased slightly, leveled off or even decreased within the treatment field with the addition of CBCT doses according to different dose response models.
  
  
  CONCLUSIONS
  The results of this study indicate that patients undergoing IMRT or RapidArc treatments with daily use of kV CBCT imaging are not subjected to additional risk due to CBCT imaging doses.
authors.affiliation: University of British Columbia, Vancouver, BC, Canada. yqiu@bccancer.bc.ca
authors.forename: Yue
authors.initials: Y
authors.lastname: Qiu
authors.forename: Vitali
authors.initials: V
authors.lastname: Moiseenko
authors.forename: Christina
authors.initials: C
authors.lastname: Aquino-Parsons
authors.forename: Cheryl
authors.initials: C
authors.lastname: Duzenli
mesh_terms: D054893:Cone-Beam Computed Tomography / Q000379:methods*; D005260:Female; D005833:Genital Neoplasms, Female / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D006801:Humans; D009010:Monte Carlo Method; D058958:Organs at Risk / Q000528:radiation effects; D010051:Ovarian Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy; D011446:Prospective Studies; D011786:Quality Control; D011832:Radiation Injuries / Q000517:prevention & control; D011836:Radiation Tolerance; D011874:Radiometry / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D011882:Radiotherapy, High-Energy / Q000379:methods*; D061089:Radiotherapy, Image-Guided / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D016896:Treatment Outcome; D014594:Uterine Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy