title: A dosimetric comparison of RapidArc and IMRT with hypofractionated simultaneous integrated boost to the prostate for treatment of prostate cancer.
abstract: OBJECTIVE
  To compare the dosimetric results and treatment delivery efficiency among RapidArc® (Varian Medical Systems, Palo Alto, CA), 7-field intensity-modulated radiotherapy (7-f IMRT) and 9-field IMRT (9-f IMRT) with hypofractionated simultaneous integrated boost to the prostate.
  
  
  METHODS
  RapidArc, 7-f IMRT and 9-f IMRT plans were created for 21 consecutive patients treated for high-risk prostate cancer using the Eclipse™ treatment planning system (Varian Medical Systems). All plans were designed to deliver 70.0 Gy in 28 fractions to the prostate planning target volume (PTV) while simultaneously delivering 50.4 Gy in 28 fractions to the pelvic nodal PTV. Target coverage and sparing of organs at risk (OARs) were compared across techniques. The total number of monitor units (MUs) and the treatment time were used to assess treatment delivery efficiency.
  
  
  RESULTS
  RapidArc resulted in slightly superior conformity and homogeneity of prostate PTV, whereas all plans were comparable with respect to dose to the nodal PTV. Although OARs sparing for RapidArc and 7-f IMRT plans were almost equivalent, 9-f IMRT achieved better sparing of the rectum and bladder than RapidArc and 7-f IMRT. RapidArc provided the highest treatment delivery efficiency with the lowest MUs and shortest treatment time.
  
  
  CONCLUSIONS
  RapidArc resulted in similar OAR sparing to 7-f IMRT, whereas 9-f IMRT provided the best OAR sparing. Treatment delivery efficiency is significantly higher for RapidArc.
  
  
  CONCLUSIONS
  This study validated the feasibility and limitations of RapidArc in the treatment of high-risk prostate cancer with complex pelvic target volumes.
authors.affiliation: Department of Radiation Oncology, Tane General Hospital, Osaka, Japan. 141kentaro@gmail.com
authors.forename: K
authors.initials: K
authors.lastname: Ishii
authors.forename: R
authors.initials: R
authors.lastname: Ogino
authors.forename: W
authors.initials: W
authors.lastname: Okada
authors.forename: R
authors.initials: R
authors.lastname: Nakahara
authors.forename: R
authors.initials: R
authors.lastname: Kawamorita
authors.forename: T
authors.initials: T
authors.lastname: Nakajima
mesh_terms: D000818:Animals; D005240:Feasibility Studies; D006801:Humans; D008297:Male; D051379:Mice; D058958:Organs at Risk; D010388:Pelvis; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011874:Radiometry / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012007:Rectum; D001743:Urinary Bladder