title: A broad scope knowledge based model for optimization of VMAT in esophageal cancer: validation and assessment of plan quality among different treatment centers.
abstract: BACKGROUND
  To evaluate the performance of a broad scope model-based optimisation process for volumetric modulated arc therapy applied to esophageal cancer.
  
  
  METHODS
  A set of 70 previously treated patients in two different institutions, were selected to train a model for the prediction of dose-volume constraints. The model was built with a broad-scope purpose, aiming to be effective for different dose prescriptions and tumour localisations. It was validated on three groups of patients from the same institution and from another clinic not providing patients for the training phase. Comparison of the automated plans was done against reference cases given by the clinically accepted plans.
  
  
  RESULTS
  Quantitative improvements (statistically significant for the majority of the analysed dose-volume parameters) were observed between the benchmark and the test plans. Of 624 dose-volume objectives assessed for plan evaluation, in 21 cases (3.3 %) the reference plans failed to respect the constraints while the model-based plans succeeded. Only in 3 cases (<0.5 %) the reference plans passed the criteria while the model-based failed. In 5.3 % of the cases both groups of plans failed and in the remaining cases both passed the tests.
  
  
  CONCLUSIONS
  Plans were optimised using a broad scope knowledge-based model to determine the dose-volume constraints. The results showed dosimetric improvements when compared to the benchmark data. Particularly the plans optimised for patients from the third centre, not participating to the training, resulted in superior quality. The data suggests that the new engine is reliable and could encourage its application to clinical practice.
authors.affiliation: Radiotherapy and Radiosurgery Department, Humanitas Clinical and Research Center, Milan-Rozzano, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Fogliata
authors.affiliation: Oncology Institute of Southern Switzerland, Bellinzona, Switzerland.
authors.forename: Giorgia
authors.initials: G
authors.lastname: Nicolini
authors.affiliation: Oncology Institute of Southern Switzerland, Bellinzona, Switzerland.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Clivio
authors.affiliation: Oncology Institute of Southern Switzerland, Bellinzona, Switzerland.
authors.forename: Eugenio
authors.initials: E
authors.lastname: Vanetti
authors.affiliation: Radiotherapy Department, Tata Memorial Hospital, Mumbai, India.
authors.forename: Sarbani
authors.initials: S
authors.lastname: Laksar
authors.affiliation: Radiotherapy and Radiosurgery Department, Humanitas Clinical and Research Center, Milan-Rozzano, Italy.
authors.forename: Angelo
authors.initials: A
authors.lastname: Tozzi
authors.affiliation: Radiotherapy and Radiosurgery Department, Humanitas Clinical and Research Center, Milan-Rozzano, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Scorsetti
authors.affiliation: Radiotherapy and Radiosurgery Department, Humanitas Clinical and Research Center, Milan-Rozzano, Italy. luca.cozzi@humanitas.it.
authors.forename: Luca
authors.initials: L
authors.lastname: Cozzi
mesh_terms: D000465:Algorithms; D004307:Dose-Response Relationship, Radiation; D004938:Esophageal Neoplasms / Q000532:radiotherapy*; D006801:Humans; D008962:Models, Theoretical; D058958:Organs at Risk / Q000528:radiation effects; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*