title: Use of FDG-PET to guide dose prescription heterogeneity in stereotactic body radiation therapy for lung cancers with volumetric modulated arc therapy: a feasibility study.
abstract: BACKGROUND
  The aim of this study was to assess if FDG-PET could guide dose prescription heterogeneity and decrease arbitrary location of hotspots in SBRT.
  
  
  METHODS
  For three patients with stage I lung cancer, a CT-simulation and a FDG-PET were registered to define respectively the PTVCT and the biological target volume (BTV). Two plans involving volumetric modulated arc therapy (VMAT) and simultaneous integrated boost (SIB) were calculated. The first plan delivered 4 × 12 Gy within the PTV(CT) and the second plan, with SIB, 4 × 12 Gy and 13.8 Gy (115% of the prescribed dose) within the PTV(CT) and the BTV respectively. The Dmax-PTV(CT) had to be inferior to 60 Gy (125% of the prescribed dose). Plans were evaluated through the D95%, D99% and Dmax-PTV(CT), the D2 cm, the R50% and R100% and the dice similarity coefficient (DSC) between the isodose 115% and BTV. DSC allows verifying the location of the 115% isodose (ideal value = 1).
  
  
  RESULTS
  The mean PTV(CT) and BTV were 36.7 (±12.5) and 6.5 (±2.2) cm3 respectively. Both plans led to similar target coverage, same doses to the OARs and equivalent fall-off of the dose outside the PTV(CT). On the other hand, the location of hotspots, evaluated through the DSC, was improved for the SIB plans with a mean DSC of 0.31 and 0.45 for the first and the second plans respectively.
  
  
  CONCLUSIONS
  Use of PET to decrease arbitrary location of hotspots is feasible with VMAT and SIB for lung cancer.
authors.forename: Bénédicte Henriques
authors.initials: BH
authors.lastname: de Figueiredo
authors.forename: Mikael
authors.initials: M
authors.lastname: Antoine
authors.forename: Renaud
authors.initials: R
authors.lastname: Trouette
authors.forename: Philippe
authors.initials: P
authors.lastname: Lagarde
authors.forename: Adeline
authors.initials: A
authors.lastname: Petit
authors.forename: Frédéric
authors.initials: F
authors.lastname: Lamare
authors.forename: Mathieu
authors.initials: M
authors.lastname: Hatt
authors.forename: Philippe
authors.initials: P
authors.lastname: Fernandez
mesh_terms: D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D005240:Feasibility Studies; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D056973:Four-Dimensional Computed Tomography; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D016634:Radiosurgery / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D014018:Tissue Distribution; D047368:Tumor Burden
chemical_list: D019788:Fluorodeoxyglucose F18