title: Implementation of an image guided intensity-modulated protocol for post-prostatectomy radiotherapy: planning data and acute toxicity outcomes.
abstract: BACKGROUND
  There is substantial interest in implementation of image-guided intensity-modulated radiotherapy (IG-IMRT) in the post-prostatectomy setting. We describe our implementation of IG-IMRT, and examine how often published organ-at-risk (OAR) constraints were met. Furthermore, we evaluate the incidence of acute genitourinary and gastrointestinal toxicities when patients were treated according to our protocol.
  
  
  METHODS
  Patients were eligible if they received post-prostatectomy radiotherapy (PPRT). Planning data were collected prospectively, and toxicity assessments were collected before, during and after treatment.
  
  
  RESULTS
  Seventy-five eligible patients received either 64 Gy (19%) or 66 Gy (81%) in a single phase to the prostate bed. Suggested rectal dose-constraints of V40Gy < 60% and V60Gy < 40% were met in 64 (85%) and 75 (100%) patients, respectively. IMRT-specific rectal dose-constraints of V40Gy < 35% and V65Gy < 17% were achieved in 5 (7%) and 57 (76%) of patients. Bladder dose-constraint (V50Gy < 50%) was met in 58 (77%) patients. Two patients (3%) experienced new grade 3 genitourinary toxicity and one patient (1%) experienced new grade 3 gastroinestinal toxicity. All grade 3 toxicities had improved by 3-month review. Overall deterioration in urinary and gastrointestinal symptoms occurred in 33 (44%) and 35 (47%) of patients respectively.
  
  
  CONCLUSIONS
  We report on our implementation of PPRT which takes into account nationally adopted guidelines, with a margin reduction supported by use of daily image guidance. Non-IMRT OAR constraints were met in most cases. IMRT-specific constraints were less often achieved despite margin reductions, suggesting the need for review of guidelines. Severe toxicity was rare, and most patients did not experience deterioration in urinary or bowel function attributable to radiotherapy.
authors.affiliation: North Coast Cancer Institute, Coffs Harbour, New South Wales, Australia. benjamin.chua@gmail.com
authors.forename: Benjamin
authors.initials: B
authors.lastname: Chua
authors.forename: Myo
authors.initials: M
authors.lastname: Min
authors.forename: Maree
authors.initials: M
authors.lastname: Wood
authors.forename: Sarah
authors.initials: S
authors.lastname: Edwards
authors.forename: Matthew
authors.initials: M
authors.lastname: Hoffmann
authors.forename: Stuart
authors.initials: S
authors.lastname: Greenham
authors.forename: Andrew
authors.initials: A
authors.lastname: Kovendy
authors.forename: Michael J
authors.initials: MJ
authors.lastname: McKay
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Shakespeare
mesh_terms: D000368:Aged; D015897:Comorbidity; D006801:Humans; D008297:Male; D009517:New South Wales / Q000453:epidemiology; D011182:Postoperative Care / Q000706:statistics & numerical data; D015995:Prevalence; D011468:Prostatectomy / Q000706:statistics & numerical data*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000628:therapy*; D011832:Radiation Injuries / Q000453:epidemiology* / Q000517:prevention & control; D011859:Radiography; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000706:statistics & numerical data*; D018714:Radiotherapy, Adjuvant / Q000706:statistics & numerical data; D020266:Radiotherapy, Conformal / Q000706:statistics & numerical data*; D061089:Radiotherapy, Image-Guided / Q000706:statistics & numerical data*; D012307:Risk Factors
keywords: computer-assisted radiotherapy planning; image-guided radiotherapy; intensity-modulated radiotherapy; prostatectomy; prostatic neoplasms