title: Effective dose reduction to cardiac structures using protons compared with 3DCRT and IMRT in mediastinal Hodgkin lymphoma.
abstract: OBJECTIVE
  We investigated the dosimetric impact of proton therapy (PT) on various cardiac subunits in patients with Hodgkin lymphoma (HL).
  
  
  METHODS
  From June 2009 through December 2010, 13 patients were enrolled on an institutional review board-approved protocol for consolidative involved-node radiotherapy (INRT) for HL. Three separate treatment plans were developed prospectively by using three-dimensional conformal radiotherapy (3DCRT), intensity-modulated radiotherapy (IMRT), and PT. Cardiac subunits were retrospectively contoured on the 11 patients with intravenous-contrast simulation scans, and the doses were calculated for all treatment plans. A Wilcoxon paired test was performed to evaluate the statistical significance (p < 0.05) of 3DCRT and IMRT compared with PT.
  
  
  RESULTS
  The mean heart doses were 21 Gy, 12 Gy, and 8 Gy (relative biologic effectiveness [RBE]) with 3DCRT, IMRT, and PT, respectively. Compared with 3DCRT and IMRT, PT reduced the mean doses to the left and right atria; the left and right ventricles; the aortic, mitral, and tricuspid valves; and the left anterior descending, left circumflex, and right circumflex coronary arteries.
  
  
  CONCLUSIONS
  Compared with 3DCRT and IMRT, PT reduced the radiation doses to all major cardiac subunits. Limiting the doses to these structures should translate into lower rates of cardiac toxicities.
authors.affiliation: Department of Radiation Oncology, University of Florida Proton Therapy Institute, Jacksonville, FL 32206, USA. bhoppe@floridaproton.org
authors.forename: Bradford S
authors.initials: BS
authors.lastname: Hoppe
authors.forename: Stella
authors.initials: S
authors.lastname: Flampouri
authors.forename: Zhong
authors.initials: Z
authors.lastname: Su
authors.forename: Naeem
authors.initials: N
authors.lastname: Latif
authors.forename: Nam H
authors.initials: NH
authors.lastname: Dang
authors.forename: James
authors.initials: J
authors.lastname: Lynch
authors.forename: Michael
authors.initials: M
authors.lastname: Joyce
authors.forename: Eric
authors.initials: E
authors.lastname: Sandler
authors.forename: Zuofeng
authors.initials: Z
authors.lastname: Li
authors.forename: Nancy P
authors.initials: NP
authors.lastname: Mendenhall
mesh_terms: D000293:Adolescent; D002648:Child; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging / Q000528:radiation effects*; D006689:Hodgkin Disease / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008479:Mediastinal Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D058958:Organs at Risk / Q000000981:diagnostic imaging / Q000528:radiation effects*; D061766:Proton Therapy; D011832:Radiation Injuries / Q000517:prevention & control; D011859:Radiography; D011877:Radionuclide Imaging; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D020266:Radiotherapy, Conformal / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D055815:Young Adult; D011522:Protons
chemical_list: D011522:Protons