title: Treatment plan comparison between stereotactic body radiation therapy techniques for prostate cancer: non-isocentric CyberKnife versus isocentric RapidArc.
abstract: OBJECTIVE
  The aim of this study was to evaluate the feasibility and dose distribution of two different stereotactic body radiation therapy (SBRT) techniques, isocentric RapidArc (RA) and non-isocentric CyberKnife (CK), for the treatment of localized prostate cancer.
  
  
  METHODS
  Two groups of patients (Groups 1 and 2 with ten patients per group) treated with CK were re-planned with RA. The patients were grouped according to the rectum constraint used (Group1, maximum dose for rectum; Group 2, dose-volume histogram for rectum). The prescription dose was 37.5 Gy in five fractions. The two SBRT techniques were compared by target coverage, normal tissue sparing, and dose distribution parameters. Monitor units (MUs) and the delivery time were likewise compared to assess delivery efficiency.
  
  
  RESULTS
  The RA plans consistently exhibited superior PTV coverage and better rectum sparing at low doses in the both groups. The conformity and heterogeneity indices of the RA plans were better than the CK plans. Additionally, the RA plans resulted in fewer low-dose regions, lower MUs, and faster delivery times than the CK plans.
  
  
  CONCLUSIONS
  The good dosimetric distribution and shorter delivery time make RA an attractive SBRT technique for the treatment of localized prostate cancer.
authors.affiliation: Department of Radiation Oncology, Chi Mei Medical Center, Tainan, Taiwan; Institute of Biomedical Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan; School of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan. Electronic address: marklin1108@gmail.com.
authors.forename: Yu-Wei
authors.initials: YW
authors.lastname: Lin
authors.affiliation: Department of Radiation Oncology, Chi Mei Medical Center, Tainan, Taiwan.
authors.forename: Kuei-Hua
authors.initials: KH
authors.lastname: Lin
authors.affiliation: Department of Radiation Oncology, Chi Mei Medical Center, Tainan, Taiwan.
authors.forename: Hsiu-Wen
authors.initials: HW
authors.lastname: Ho
authors.affiliation: Department of Radiation Oncology, Chi Mei Medical Center, Tainan, Taiwan.
authors.forename: Hsiu-Man
authors.initials: HM
authors.lastname: Lin
authors.affiliation: Department of Radiation Oncology, Chi Mei Medical Center, Tainan, Taiwan; School of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Li-Ching
authors.initials: LC
authors.lastname: Lin
authors.affiliation: Department of Radiation Oncology, David Geffen School of Medicine of The University of California Los Angeles, Los Angeles, CA, USA.
authors.forename: Steve P
authors.initials: SP
authors.lastname: Lee
authors.affiliation: Department of Medical Physics, Koo Foundation Sun Yat-Sen Cancer Center, Taipei, Taiwan.
authors.forename: Chen-Shou
authors.initials: CS
authors.lastname: Chui
mesh_terms: D006801:Humans; D008297:Male; D059351:Organ Sparing Treatments; D011471:Prostatic Neoplasms / Q000532:radiotherapy / Q000601:surgery*; D016634:Radiosurgery / Q000009:adverse effects / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*
keywords: CyberKnife; Prostate cancer; RapidArc; Stereotactic body radiation therapy; Volumetric modulated arc therapy