title: DEMAT: A multi-institutional dosimetry audit of rotational and static intensity-modulated radiotherapy.
abstract: OBJECTIVE
  Static beam intensity-modulated-radiation-therapy (IMRT) and/or Volumetric-Modulated-Arc-Therapy (VMAT) are now available in many regional radiotherapy departments. The aim of this multi-institutional audit was to design a new methodology based on radiochromic films to perform an independent quality control.
  
  
  METHODS
  A set of data were sent to all participating centres for two clinical localizations: prostate and Head and Neck (H&N) cancers. The agreement between calculations and measurements was verified in the Octavius phantom (PTW) by point measurements using ionization chambers and by 2D measurements using EBT3 radiochromic films. Due to uncertainties in the whole procedure, criteria were set to 5% and 3% in local dose and 3mm in distance excluding doses lower than 10% of the maximum doses. No normalization point or area was used for the quantitative analysis.
  
  
  RESULTS
  13 radiotherapy centres participated in this audit involving 28 plans (12 IMRT, 16 VMAT). For point measurements, mean errors were -0.18±1.54% and 0.00±1.58% for prostate and H&N cases respectively. For 2D measurements with 5%/3mm criteria, gamma map analysis showed a pixel pass rate higher than 95% for prostate and H&N. Mean gamma index was lower than 0.4 for prostate and 0.5 for H&N. Both techniques yielded similar results.
  
  
  CONCLUSIONS
  This study showed the feasibility of an independent quality control by peers for conventional IMRT and VMAT. Results from all participating centres were found to be in good agreement. This regional study demonstrated the feasibility of our new methodology based on radiochromic films without dose normalization on a specific point.
authors.affiliation: Centre Eugène Marquis, 35042 Rennes, France. Electronic address: c.lafond@rennes.unicancer.fr.
authors.forename: Caroline
authors.initials: C
authors.lastname: Lafond
authors.affiliation: Institut de Cancérologie de l'Ouest Centre René Gauducheau, 44805 Saint-Herblain, Nantes, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Chiavassa
authors.affiliation: Centre Eugène Marquis, 35042 Rennes, France.
authors.forename: Cindy
authors.initials: C
authors.lastname: Bertaut
authors.affiliation: CHRU, 29609 Brest, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Boussion
authors.affiliation: Clinique Pasteur, 29200 Brest, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Chapel
authors.affiliation: Clinique Armoricaine, 22000 Saint-Brieuc, France.
authors.forename: Lucie
authors.initials: L
authors.lastname: Chapron
authors.affiliation: Pôle Mutualiste, 44600 Saint-Nazaire, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Coste
authors.affiliation: CHD Les Oudairies, 85925 La Roche sur Yon, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Crespin
authors.affiliation: Clinique Saint-Vincent, 35760 Saint-Grégoire, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Dy
authors.affiliation: Institut de Cancérologie de l'Ouest Centre René Gauducheau, 44805 Saint-Herblain, Nantes, France.
authors.forename: Papa Abdoulaye
authors.initials: PA
authors.lastname: Faye
authors.affiliation: CHI, 29000 Quimper, France.
authors.forename: Cyril
authors.initials: C
authors.lastname: Leleu
authors.affiliation: Centre Eugène Marquis, 35042 Rennes, France.
authors.forename: Jeanne
authors.initials: J
authors.lastname: Bouvier
authors.affiliation: Centre de la Baie, 50300 Avranches, France.
authors.forename: Ludovic
authors.initials: L
authors.lastname: Madec
authors.affiliation: Institut de Cancérologie de l'Ouest Centre Paul Papin, 49100 Angers, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Mesgouez
authors.affiliation: Centre Mallet-Proux, 53000 Laval, France.
authors.forename: Jérémy
authors.initials: J
authors.lastname: Palisson
authors.affiliation: Centre François Baclesse, 14000 Caen, France.
authors.forename: Anthony
authors.initials: A
authors.lastname: Vela
authors.affiliation: Institut de Cancérologie de l'Ouest Centre René Gauducheau, 44805 Saint-Herblain, Nantes, France.
authors.forename: Grégory
authors.initials: G
authors.lastname: Delpon
mesh_terms: D002138:Calibration; D005373:Film Dosimetry; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D019047:Phantoms, Imaging; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011786:Quality Control; D011874:Radiometry; D011878:Radiotherapy / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012399:Rotation
keywords: Audit; IMRT; VMAT