title: Dosimetric evaluation of Acuros XB Advanced Dose Calculation algorithm in heterogeneous media.
abstract: BACKGROUND
  A study was realised to evaluate and determine relative figures of merit of a new algorithm for photon dose calculation when applied to inhomogeneous media.
  
  
  METHODS
  The new Acuros XB algorithm implemented in the Varian Eclipse treatment planning system was compared against a Monte Carlo method (VMC++), and the Analytical Anisotropic Algorithm (AAA). The study was carried out in virtual phantoms characterized by simple geometrical structures. An insert of different material and density was included in a phantom built of skeletal-muscle and HU = 0 (setting "A"): Normal Lung (lung, 0.198 g/cm3); Light Lung (lung, 0.035 g/cm3); Bone (bone, 1.798 g/cm3); another phantom (setting "B") was built of adipose material and including thin layers of bone (1.85 g/cm3), adipose (0.92 g/cm3), cartilage (1.4745 g/cm3), air (0.0012 g/cm3). Investigations were performed for 6 and 15 MV photon beams, and for a large (13 × 13 cm2) and a small (2.8 × 13 cm2) field.
  
  
  RESULTS
  Results are provided in terms of depth dose curves, transverse profiles and Gamma analysis (3 mm/3% and 2 mm/2% distance to agreement/dose difference criteria) in planes parallel to the beam central axis; Monte Carlo simulations were assumed as reference. Acuros XB gave an average gamma agreement, with a 3 mm/3% criteria, of 100%, 86% and 100% for Normal Lung, Light Lung and Bone settings, respectively, and dose to medium calculations. The same figures were 86%, 11% and 100% for AAA, where only dose rescaled to water calculations are possible.
  
  
  CONCLUSIONS
  In conclusion, Acuros XB algorithm provides a valid and accurate alternative to Monte Carlo calculations for heterogeneity management.
authors.affiliation: Medical Physics Unit, Oncology Institute of Southern Switzerland, Bellinzona, Switzerland. afc@iosi.ch
authors.forename: Antonella
authors.initials: A
authors.lastname: Fogliata
authors.forename: Giorgia
authors.initials: G
authors.lastname: Nicolini
authors.forename: Alessandro
authors.initials: A
authors.lastname: Clivio
authors.forename: Eugenio
authors.initials: E
authors.lastname: Vanetti
authors.forename: Luca
authors.initials: L
authors.lastname: Cozzi
mesh_terms: D000465:Algorithms; D016880:Anisotropy; D005720:Gamma Rays; D006801:Humans; D015233:Models, Statistical; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D017785:Photons / Q000627:therapeutic use; D011381:Programming Languages; D011874:Radiometry / Q000379:methods*; D011878:Radiotherapy / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D015203:Reproducibility of Results; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water