title: Increased organ sparing using shape-based treatment plan optimization for intensity modulated radiation therapy of pancreatic adenocarcinoma.
abstract: OBJECTIVE
  To develop a model to assess the quality of an IMRT treatment plan using data of prior patients with pancreatic adenocarcinoma.
  
  
  METHODS
  The dose to an organ at risk (OAR) depends in large part on its orientation and distance to the planning target volume (PTV). A database of 33 previously treated patients with pancreatic cancer was queried to find patients with less favorable PTV-OAR configuration than a new case. The minimal achieved dose among the selected patients should also be achievable for the OAR of the new case. This way the achievable doses to the OARs of 25 randomly selected pancreas cancer patients were predicted. The patients were replanned to verify if the predicted dose could be achieved. The new plans were compared to their original clinical plans.
  
  
  RESULTS
  The predicted doses were achieved within 1 and 2 Gy for more than 82% and 94% of the patients, respectively, and were a good approximation of the minimal achievable doses. The improvement after replanning was 1.4 Gy (range 0-4.6 Gy) and 1.7 Gy (range 0-6.3 Gy) for the mean dose to the liver and the kidneys, respectively, without compromising target coverage or increasing radiation dose to the bowel, cord or stomach.
  
  
  CONCLUSIONS
  The model could accurately predict the achievable doses, leading to a considerable decrease in dose to the OARs and an increase in treatment planning efficiency.
authors.affiliation: Department of Computer Science, Johns Hopkins University, Baltimore, USA. s.petit@erasmusmc.nl
authors.forename: Steven F
authors.initials: SF
authors.lastname: Petit
authors.forename: Binbin
authors.initials: B
authors.lastname: Wu
authors.forename: Michael
authors.initials: M
authors.lastname: Kazhdan
authors.forename: André
authors.initials: A
authors.lastname: Dekker
authors.forename: Patricio
authors.initials: P
authors.lastname: Simari
authors.forename: Rachit
authors.initials: R
authors.lastname: Kumar
authors.forename: Russel
authors.initials: R
authors.lastname: Taylor
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Herman
authors.forename: Todd
authors.initials: T
authors.lastname: McNutt
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D007668:Kidney / Q000528:radiation effects; D008099:Liver / Q000528:radiation effects; D008297:Male; D010190:Pancreatic Neoplasms / Q000188:drug therapy / Q000532:radiotherapy*; D011237:Predictive Value of Tests; D011786:Quality Control; D011829:Radiation Dosage; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome