title: Improved robotic stereotactic body radiation therapy plan quality and planning efficacy for organ-confined prostate cancer utilizing overlap-volume histogram-driven planning methodology.
abstract: OBJECTIVE
  This study is to determine if the overlap-volume histogram (OVH)-driven planning methodology can be adapted to robotic SBRT (CyberKnife Robotic Radiosurgery System) to further minimize the bladder and rectal doses achieved in plans manually-created by clinical planners.
  
  
  METHODS
  A database containing clinically-delivered, robotic SBRT plans (7.25 Gy/fraction in 36.25 Gy) of 425 patients with localized prostate cancer was used as a cohort to establish an organ's distance-to-dose model. The OVH-driven planning methodology was refined by adding the PTV volume factor to counter the target's dose fall-off effect and incorporated into Multiplan to automate SBRT planning. For validation, automated plans (APs) for 12 new patients were generated, and their achieved dose/volume values were compared to the corresponding manually-created, clinically-delivered plans (CPs). A two-sided, Wilcoxon rank-sum test was used for statistical comparison with a significance level of p<0.05.
  
  
  RESULTS
  PTV's V(36.25 Gy) was comparable: 95.6% in CPs comparing to 95.1% in APs (p=0.2). On average, the refined approach lowered V(18.12 Gy) to the bladder and rectum by 8.2% (p<0.05) and 6.4% (p=0.14). A physician confirmed APs were clinically acceptable.
  
  
  CONCLUSIONS
  The improvements in APs could further reduce toxicities observed in SBRT for organ-confined prostate cancer.
authors.affiliation: Department of Radiation Medicine, Georgetown University Hospital, Washington, USA. Electronic address: binbin.wu@gunet.georgetown.edu.
authors.forename: Binbin
authors.initials: B
authors.lastname: Wu
authors.affiliation: Department of Radiation Medicine, Georgetown University Hospital, Washington, USA.
authors.forename: Dalong
authors.initials: D
authors.lastname: Pang
authors.affiliation: Department of Radiation Medicine, Georgetown University Hospital, Washington, USA.
authors.forename: Siyuan
authors.initials: S
authors.lastname: Lei
authors.affiliation: Department of Radiation Medicine, Georgetown University Hospital, Washington, USA.
authors.forename: John
authors.initials: J
authors.lastname: Gatti
authors.affiliation: Department of Radiation Medicine, Georgetown University Hospital, Washington, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Tong
authors.affiliation: Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University, Baltimore, USA.
authors.forename: Todd
authors.initials: T
authors.lastname: McNutt
authors.affiliation: Department of Radiation Medicine, Georgetown University Hospital, Washington, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kole
authors.affiliation: Department of Radiation Medicine, Georgetown University Hospital, Washington, USA.
authors.forename: Anatoly
authors.initials: A
authors.lastname: Dritschilo
authors.affiliation: Department of Radiation Medicine, Georgetown University Hospital, Washington, USA.
authors.forename: Sean
authors.initials: S
authors.lastname: Collins
mesh_terms: D006801:Humans; D008297:Male; D009929:Organ Size; D058958:Organs at Risk / Q000033:anatomy & histology / Q000528:radiation effects; D010934:Planning Techniques; D011471:Prostatic Neoplasms / Q000601:surgery*; D016634:Radiosurgery / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted / Q000009:adverse effects / Q000379:methods*; D012007:Rectum / Q000033:anatomy & histology / Q000528:radiation effects; D012371:Robotics / Q000379:methods; D001743:Urinary Bladder / Q000033:anatomy & histology / Q000528:radiation effects
keywords: CyberKnife; OVH; Prostate; SBRT