title: Rotational setup errors in pediatric stereotactic radiation therapy.
abstract: OBJECTIVE
  Stereotactic radiation therapy (SRT) is an increasingly commonly used technique in children. The use of image guidance increases the ability to accurately position patients. With our robotic couch, rotational errors that can be corrected are limited to approximately 3 degrees. Given this limitation, we reviewed the rotational setup errors in our pediatric brain tumor population.
  
  
  METHODS
  We reviewed the rotational corrections for all pediatric (age ≤21 years old) patients treated at our facility from 2009 to 2011. We compared children <5 years old treated to children between 5 and 21 years old (≥5 years old). Also, we analyzed the effect of steroid use and trends in rotational errors over the treatment period in each age group.
  
  
  RESULTS
  The mean pitch, roll, and yaw rotational setup errors for younger children are -0.70 ± 2.60 degrees, -0.06 ± 1.89 degrees, and 0.69 ± 2.42 degrees, respectively; for children ≥5 years old, they are 0.46 ± 2.09 degrees, -0.06 ± 1.89 degrees, and 0.69 ± 2.42 degrees, respectively. The mean pitch corrections are larger for children <5 years old (P < .001) and the variance of the pitch, roll, and yaw corrections are all larger for children <5 years old (P < .001). The frequency of rotational errors above 3 degrees for pitch, roll, and yaw is 21.7%, 10.6%, and 20.9% for children <5 years old, and 15.6%, 2.1%, and 13.8% for children ≥5 years old. In both age groups, pitch and roll corrections were larger for children treated with steroids.
  
  
  CONCLUSIONS
  Rotational errors in our pediatric population occur more frequently than previously reported, and are more common in younger children and in children treated with steroids. These rotational set up errors may not be fully correctable due to mechanical and safety limitations. We have altered our planning and treatment process to better account for rotational errors in children receiving SRT.
authors.affiliation: Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado. Electronic address: cem.altunbas@ucdenver.edu.
authors.forename: Cem
authors.initials: C
authors.lastname: Altunbas
authors.affiliation: Department of Neurosurgery, Children's Hospital Colorado, Aurora, Colorado.
authors.forename: Todd C
authors.initials: TC
authors.lastname: Hankinson
authors.affiliation: Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado.
authors.forename: Moyed
authors.initials: M
authors.lastname: Miften
authors.affiliation: Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado.
authors.forename: Tiffany
authors.initials: T
authors.lastname: Tello
authors.affiliation: Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Plimpton
authors.affiliation: Department of Radiation Oncology, University of Colorado Hospital, Aurora, Colorado.
authors.forename: Kelly
authors.initials: K
authors.lastname: Stuhr
authors.affiliation: Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado.
authors.forename: Arthur K
authors.initials: AK
authors.lastname: Liu