title: GafChromic(®) EBT3 films for patient specific IMRT QA using a multichannel approach.
abstract: OBJECTIVE
  To evaluate EBT3 for pre-treatment patient specific quality assurance (QA). The method we propose combines the experience gained in our center with the guidelines of the protocol proposed by Lewis et al. in 2012. To compare the multichannel approach with the single channel dosimetry.
  
  
  METHODS
  Gafchromic® EBT3 films were irradiated both at linac and TomoTherapy and calibration curves were obtained. A series of irradiations with simple fields (uniform dose distributions on regular shaped targets) was performed. In a second stage, films were exposed to full clinical plans at linac (step and shoot IMRT and VMAT). At TomoTherapy dose maps were obtained for a clinical plan in three different coronal planes. Films were digitized using an Epson 10000XL scanner and FilmQA™ Pro software was employed for the analysis.
  
  
  RESULTS
  The measured calibration curves suggest that, at least for the two beams taken into account (6 MV linac and TomoTherapy), a single calibration can be successfully adopted for each film lot. The application of the multichannel optimization method strongly improves the results in terms of gamma passing rates of the comparison between measured and calculated maps.
  
  
  CONCLUSIONS
  Up to now EBT films, although attractive, were not preferred for routine patient specific QA due to their complex and time consuming processing and to the challenging work of characterization. The application of the mentioned protocol, together with some additional precautions, and the adoption of the multichannel optimization dosimetry, make this detector a handy and reliable tool for patient specific QA.
authors.affiliation: Medical Physics Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy. Electronic address: livia.marrazzo@unifi.it.
authors.forename: Livia
authors.initials: L
authors.lastname: Marrazzo
authors.affiliation: Dipartimento di Scienze Biomediche, Sperimentali e Cliniche, Università degli Studi di Firenze, Florence, Italy.
authors.forename: Margherita
authors.initials: M
authors.lastname: Zani
authors.affiliation: Medical Physics Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy; Dipartimento di Scienze Biomediche, Sperimentali e Cliniche, Università degli Studi di Firenze, Florence, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Pallotta
authors.affiliation: Medical Physics Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Arilli
authors.affiliation: Medical Physics Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Casati
authors.affiliation: Medical Physics Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Compagnucci
authors.affiliation: Medical Physics Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy; Dipartimento di Scienze Biomediche, Sperimentali e Cliniche, Università degli Studi di Firenze, Florence, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Talamonti
authors.affiliation: Medical Physics Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy; Dipartimento di Scienze Biomediche, Sperimentali e Cliniche, Università degli Studi di Firenze, Florence, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Bucciolini
mesh_terms: D002138:Calibration; D005373:Film Dosimetry / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D010315:Particle Accelerators; D011785:Quality Assurance, Health Care; D050397:Radiotherapy, Intensity-Modulated
keywords: IMRT; Multichannel dosimetry; Patient specific quality assurance; Radiochromic film