title: A practical tool to evaluate dose distributions using radiochromic film in radiation oncology.
abstract: OBJECTIVE
  Triple channel algorithm and specific procedures make more reliable radiochromic dosimetry for treatment planning verification and quality assurance in radiation therapy. A tool to obtain radiochromic dose distributions and compare them with the ones resulting from a treatment planning system was developed and applied.
  
  
  METHODS
  The tool was developed as Microsoft Excel macro; it builds dose calibration curves against net optical density of Gafchromic EBT3 film, produces axial, coronal and sagittal dose maps and allows to evaluate them against dose distributions calculated by the Varian treatment planning system Eclipse using gamma index and gamma angle.
  
  
  RESULTS
  The net optical density standard errors of estimate of calibration curves at 6 MV Varian DBX600 linac energy were 0.2%, 0.4% and 0.2% for the red, green and blue channels. Tests of these curves by means of three independent eight dose points measurement series, at 15 MV and 6 MV Varian 2100C linac and at 6 MV DBX600 linac energies, showed less than 2% of dose errors for the red channel and less than 3% for the green channel in the range 100-450 cGy. The comparisons between dose distributions from Gafchromic EBT3 triple channel algorithm and the ones from Eclipse analytic anisotropic algorithm (AAA) showed values of gamma index 95th percentile between 0.6 and 1.0.
  
  
  CONCLUSIONS
  The obtained results encourage the application of this tool in radiation therapy quality assurance.
authors.affiliation: Medical Physics Unit, ASL Sassari, Via Enrico de Nicola, Sassari, Italy. Electronic address: mtamponi@aslsassari.it.
authors.forename: M
authors.initials: M
authors.lastname: Tamponi
authors.affiliation: Medical Physics Unit, ASL Sassari, Via Enrico de Nicola, Sassari, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Bona
authors.affiliation: Medical Physics Unit, ASL Sassari, Via Enrico de Nicola, Sassari, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Poggiu
authors.affiliation: Medical Physics Unit, ASL Sassari, Via Enrico de Nicola, Sassari, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Marini
mesh_terms: D000465:Algorithms; D002138:Calibration; D005373:Film Dosimetry / Q000379:methods*; D011829:Radiation Dosage; D018787:Radiation Oncology; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012984:Software; D035501:Uncertainty
keywords: Gamma index analysis; Quality assurance; Radiochromic dosimetry; Treatment planning verification