title: [Magnetic resonance imaging for delineation of prostate in radiotherapy: monocentric experience and review of literature].
abstract: OBJECTIVE
  To assess the benefits of magnetic resonance imaging (MRI) in the dosimetric treatment planning for prostate radiotherapy.
  
  
  METHODS
  Ten consecutive patients have been enrolled. They were treated for a low risk prostate adenocarcinoma. A rigid superimposition was performed between MRI and scan slides obtained at time of virtual simulation, then prostate volume was delineated by four to five physicians, on TDM slides and on MRI/TDM superimposition. For each treatment plan, we assessed the impact of MRI in terms of planned treatment volume (PTV) position, individual variability of prostate delineation and doses delivered to the critical organs. The prescribed dose was 74 Gy in 37 fractions to the PTV.
  
  
  RESULTS
  PTV delineated on TDM (V(TDM)) were 1.15 (SD 3.71) larger than volumes delineated on MRI. Prostate apex was 4.6 mm (SD 2.87) lower on TDM than on MRI. Posterior limit of the prostate was in mean 4 mm more posterior on TDM. The variability between physicians in terms of prostate delineation was lower using MRI. For apex, these variations were 6.8 mm using TDM, versus 3.3 mm using MRI. Mean rectal dose was 8 % lower with MRI, compared to delineation using TDM.
  
  
  CONCLUSIONS
  Superimposition TDM/MRI improves accuracy, decreases delineation variability, and allows to spare anterior part of the rectum from irradiation. It remains unknown whether this strategy translates into clinical benefit.
authors.affiliation: Département de radiothérapie, institut de cancérologie de la Loire, 108 bis, avenue Albert-Raimond, BP 60008, 42271 Saint-Priest-en-Jarez cedex, France.
authors.forename: P
authors.initials: P
authors.lastname: Auberdiac
authors.forename: C
authors.initials: C
authors.lastname: Chargari
authors.forename: F
authors.initials: F
authors.lastname: Négrier
authors.forename: C
authors.initials: C
authors.lastname: Boutinaud
authors.forename: A
authors.initials: A
authors.lastname: Zioueche
authors.forename: L
authors.initials: L
authors.lastname: Cartier
authors.forename: B
authors.initials: B
authors.lastname: Leduc
authors.forename: J-P
authors.initials: JP
authors.lastname: Dumas
authors.forename: P
authors.initials: P
authors.lastname: Colombeau
authors.forename: G
authors.initials: G
authors.lastname: de Laroche
authors.forename: N
authors.initials: N
authors.lastname: Magné
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology* / Q000532:radiotherapy*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011471:Prostatic Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D011880:Radiotherapy Planning, Computer-Assisted