title: Validation of the Oncentra Brachy Advanced Collapsed cone Engine for a commercial (192)Ir source using heterogeneous geometries.
abstract: OBJECTIVE
  To validate the Advanced Collapsed cone Engine (ACE) dose calculation engine of Oncentra Brachy (OcB) treatment planning system using an (192)Ir source.
  
  
  METHODS
  Two levels of validation were performed, conformant to the model-based dose calculation algorithm commissioning guidelines of American Association of Physicists in Medicine TG-186 report. Level 1 uses all-water phantoms, and the validation is against TG-43 methodology. Level 2 uses real-patient cases, and the validation is against Monte Carlo (MC) simulations. For each case, the ACE and TG-43 calculations were performed in the OcB treatment planning system. ALGEBRA MC system was used to perform MC simulations.
  
  
  RESULTS
  In Level 1, the ray effect depends on both accuracy mode and the number of dwell positions. The volume fraction with dose error ≥2% quickly reduces from 23% (13%) for a single dwell to 3% (2%) for eight dwell positions in the standard (high) accuracy mode. In Level 2, the 10% and higher isodose lines were observed overlapping between ACE (both standard and high-resolution modes) and MC. Major clinical indices (V100, V150, V200, D90, D50, and D2cc) were investigated and validated by MC. For example, among the Level 2 cases, the maximum deviation in V100 of ACE from MC is 2.75% but up to ~10% for TG-43. Similarly, the maximum deviation in D90 is 0.14 Gy between ACE and MC but up to 0.24 Gy for TG-43.
  
  
  CONCLUSIONS
  ACE demonstrated good agreement with MC in most clinically relevant regions in the cases tested. Departure from MC is significant for specific situations but limited to low-dose (<10% isodose) regions.
authors.affiliation: Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec, Canada; Département de radio-oncologie et CRCHU de Québec, CHU de Québec, Québec, Canada. Electronic address: yunzhi7@yahoo.com.
authors.forename: Yunzhi
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec, Canada.
authors.forename: Fréderic
authors.initials: F
authors.lastname: Lacroix
authors.affiliation: Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec, Canada.
authors.forename: Marie-Claude
authors.initials: MC
authors.lastname: Lavallée
authors.affiliation: Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec, Canada; Département de radio-oncologie et CRCHU de Québec, CHU de Québec, Québec, Canada.
authors.forename: Luc
authors.initials: L
authors.lastname: Beaulieu
mesh_terms: D000465:Algorithms; D001918:Brachytherapy; D006801:Humans; D007496:Iridium Radioisotopes / Q000627:therapeutic use*; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*
chemical_list: D007496:Iridium Radioisotopes
keywords: ACE; Advanced Collapsed cone Engine; Brachytherapy; Collapsed-cone convolution; Dose calculation