title: Aortic dose constraints when reirradiating thoracic tumors.
abstract: OBJECTIVE
  Improved radiation delivery and planning has allowed, in some instances, for the retreatment of thoracic tumors. We investigated the dose limits of the aorta wherein grade 5 aortic toxicity was observed after reirradiation of lung tumors.
  
  
  METHODS
  In a retrospective analysis, 35 patients were identified, between 1993 and 2008, who received two rounds of external beam irradiation that included the aorta in the radiation fields of both the initial and retreatment plans. We determined the maximum cumulative dose to 1 cm(3) of the aorta (the composite dose) for each patient, normalized these doses to 1.8 Gy/fraction, and corrected them for long-term tissue recovery between treatments (NIDR).
  
  
  RESULTS
  The median time interval between treatments was 30 months (range, 1-185 months). The median follow-up of patients alive at analysis was 42 months (range, 14-70 months). Two of the 35 patients (6%) were identified as having grade 5 aortic toxicities. There was a 25% rate of grade 5 aortic toxicity for patients receiving composite doses ≥120.0 Gy (vs. 0% for patients receiving <120.0 Gy) (P=0.047).
  
  
  CONCLUSIONS
  Grade 5 aortic toxicities were observed with composite doses ≥120.0 Gy (NIDR ≥90.0 Gy) to 1cm(3) of the aorta.
authors: Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, United States.
authors: Jaden D
authors: JD
authors: Evans
authors: Daniel R
authors: DR
authors: Gomez
authors: Arya
authors: A
authors: Amini
authors: Neal
authors: N
authors: Rebueno
authors: Pamela K
authors: PK
authors: Allen
authors: Mary K
authors: MK
authors: Martel
authors: Justin M
authors: JM
authors: Rineer
authors: Kie Kian
authors: KK
authors: Ang
authors: Sarah
authors: S
authors: McAvoy
authors: James D
authors: JD
authors: Cox
authors: Ritsuko
authors: R
authors: Komaki
authors: James W
authors: JW
authors: Welsh
mesh_terms: D000328:Adult; D000368:Aged; D001011:Aorta / Q000528:radiation effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D013899:Thoracic Neoplasms / Q000532:radiotherapy*