title: Endorectal balloon reduces anorectal doses in post-prostatectomy intensity-modulated radiotherapy.
abstract: OBJECTIVE
  To investigate the effect of an endorectal balloon (ERB) on anal wall (Awall) and rectal wall (Rwall) doses in high-dose post-prostatectomy intensity-modulated radiotherapy (IMRT).
  
  
  METHODS
  For 20 patients, referred for salvage IMRT after prostatectomy for prostate cancer, two planning CT-scans were performed: one with and one without an air-filled ERB. A planning target volume (PTV) was defined, using international guidelines. Furthermore, the Awall and Rwall were delineated. In both the scans, IMRT plans were generated with a prescribed dose of 70 Gy. The mean dose (D(mean)), maximum dose, minimum dose, and volumes exposed to doses ranging from ≥ 20 to ≥ 70 Gy (V(20)-V(70)) to the Awall and Rwall were calculated. Finally, inner Rwall surface areas exposed to doses ranging from ≥ 20 to ≥ 70 Gy (A(20)-A(70)) were calculated. Dose-parameters were compared between plans with and without ERB.
  
  
  RESULTS
  All Awall parameters, except V(70), were significantly reduced by the ERB with an overall D(mean) reduction of 6 Gy. Absolute reductions in dose-volume parameters varied from 5% to 11%. Significantly reduced Rwall V(30), V(40), and A(40) were observed with ERB, irrespective of the target volume size.
  
  
  CONCLUSIONS
  ERB application significantly reduces Awall and to a lesser degree Rwall doses in high-dose post-prostatectomy IMRT.
authors.affiliation: Department of Radiation Oncology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. r.smeenk@rther.umcn.nl
authors.forename: Robert Jan
authors.initials: RJ
authors.lastname: Smeenk
authors.forename: Emile N J Th
authors.initials: EN
authors.lastname: van Lin
authors.forename: Peter
authors.initials: P
authors.lastname: van Kollenburg
authors.forename: Gill M
authors.initials: GM
authors.lastname: McColl
authors.forename: Martina
authors.initials: M
authors.lastname: Kunze-Busch
authors.forename: Johannes H A M
authors.initials: JH
authors.lastname: Kaanders
mesh_terms: D001003:Anal Canal / Q000528:radiation effects*; D002404:Catheterization; D006801:Humans; D008297:Male; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012007:Rectum / Q000528:radiation effects*