title: Multidimensional dosimetry of ¹⁰⁶Ru eye plaques using EBT3 films and its impact on treatment planning.
abstract: OBJECTIVE
  The purpose of this study was to establish a method to perform multidimensional radiochromic film measurements of (106)Ru plaques and to benchmark the resulting dose distributions against Monte Carlo simulations (MC), microdiamond, and diode measurements.
  
  
  METHODS
  Absolute dose rates and relative dose distributions in multiple planes were determined for three different plaque models (CCB, CCA, and COB), and three different plaques per model, using EBT3 films in an in-house developed polystyrene phantom and the mcnp6 MC code. Dose difference maps were generated to analyze interplaque variations for a specific type, and for comparing measurements against MC simulations. Furthermore, dose distributions were validated against values specified by the manufacturer (BEBIG) and microdiamond and diode measurements in a water scanning phantom. Radial profiles were assessed and used to estimate dosimetric margins for a given combination of representative tumor geometry and plaque size.
  
  
  RESULTS
  Absolute dose rates at a reference depth of 2 mm on the central axis of the plaque show an agreement better than 5% (10%) when comparing film measurements (mcnp6) to the manufacturer's data. The reproducibility of depth-dose profile measurements was <7% (2 SD) for all investigated detectors and plaque types. Dose difference maps revealed minor interplaque deviations for a specific plaque type due to inhomogeneities of the active layer. The evaluation of dosimetric margins showed that for a majority of the investigated cases, the tumor was not completely covered by the 100% isodose prescribed to the tumor apex if the difference between geometrical plaque size and tumor base ≤4 mm.
  
  
  CONCLUSIONS
  EBT3 film dosimetry in an in-house developed phantom was successfully used to characterize the dosimetric properties of different (106)Ru plaque models. The film measurements were validated against MC calculations and other experimental methods and showed a good agreement with data from BEBIG well within published tolerances. The dosimetric information as well as interplaque comparison can be used for comprehensive quality assurance and for considerations in the treatment planning of ophthalmic brachytherapy.
authors.affiliation: Department of Radiation Oncology/Comprehensive Cancer Center, Medical University of Vienna/AKH Vienna, Vienna 1090, Austria.
authors.forename: G
authors.initials: G
authors.lastname: Heilemann
authors.affiliation: Department of Radiation Oncology/Comprehensive Cancer Center, Medical University of Vienna/AKH Vienna, Vienna 1090, Austria and Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Vienna 1090, Austria.
authors.forename: N
authors.initials: N
authors.lastname: Nesvacil
authors.affiliation: Health and Environment Department Biomedical Systems, Austrian Institute of Technology GmbH, Vienna 1220, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Blaickner
authors.affiliation: Department of Radiation Oncology/Comprehensive Cancer Center, Medical University of Vienna/AKH Vienna, Vienna 1090, Austria.
authors.forename: N
authors.initials: N
authors.lastname: Kostiukhina
authors.affiliation: Department of Radiation Oncology/Comprehensive Cancer Center, Medical University of Vienna/AKH Vienna, Vienna 1090, Austria and Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Vienna 1090, Austria.
authors.forename: D
authors.initials: D
authors.lastname: Georg
mesh_terms: D005134:Eye Neoplasms / Q000532:radiotherapy*; D005373:Film Dosimetry / Q000379:methods*; D006801:Humans; D009010:Monte Carlo Method; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012429:Ruthenium Radioisotopes / Q000627:therapeutic use*
chemical_list: D012429:Ruthenium Radioisotopes