title: Is the lack of respiratory gating prejudicial for left breast TomoDirect treatments?
abstract: OBJECTIVE
  TomoDirect (TD) can only operate in free-breathing. The purpose of this study is to compare TD with breath-hold 3D conformal radiotherapy (3DCRT) and intensity modulated radiotherapy (IMRT) techniques for left breast treatments, and to determine if the lack of respiratory gating is a handicap for cardiac sparing.
  
  
  METHODS
  15 patients treated for left breast had two computed tomography simulation, in free breathing (FB) and in deep-inspiration breath-hold (DIBH). Four treatments were planned: TD-FB, 3DCRT-FB, 3DCRT-DIBH and IMRT-DIBH. Dose to PTV, heart, lungs, right breast and patient were compared.
  
  
  RESULTS
  A slightly lower cardiac mean dose is found for 3DCRT-DIBH than for TD-FB group (1.99Gy Vs 2.89Gy, p=0.0462), while no statistical difference is found for heart V20. TD-FB plans show the best PTV dose homogeneity (0.053, p<0.001) and the lowest left lung mean dose (5.16Gy, p<0.001). No major differences are found for the other organs.
  
  
  CONCLUSIONS
  TomoDirect and breath-hold 3DCRT are complementary techniques for left breast treatments: for a minority of patients, respiratory gating is mandatory to lower cardiac dose; for the remaining majority of patients, TomoDirect achieves better PTV homogeneity and reduced left lung dose, with cardiac dose equivalent to 3DCRT-DIBH.
authors.affiliation: Division of Medical Physics, Department of Radiotherapy, Paul Strauss Center, Strasbourg, France. Electronic address: pmeyer@strasbourg.unicancer.fr.
authors.forename: Philippe
authors.initials: P
authors.lastname: Meyer
authors.affiliation: Division of Medical Physics, Department of Radiotherapy, Paul Strauss Center, Strasbourg, France.
authors.forename: Claudine
authors.initials: C
authors.lastname: Niederst
authors.affiliation: Division of Medical Physics, Department of Radiotherapy, Paul Strauss Center, Strasbourg, France.
authors.forename: Maximilien
authors.initials: M
authors.lastname: Scius
authors.affiliation: Division of Medical Physics, Department of Radiotherapy, Paul Strauss Center, Strasbourg, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Jarnet
authors.affiliation: Division of Medical Physics, Department of Radiotherapy, Paul Strauss Center, Strasbourg, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Dehaynin
authors.affiliation: Division of Medical Physics, Department of Radiotherapy, Paul Strauss Center, Strasbourg, France.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Gantier
authors.affiliation: Division of Medical Physics, Department of Radiotherapy, Paul Strauss Center, Strasbourg, France.
authors.forename: Waisse
authors.initials: W
authors.lastname: Waissi
authors.affiliation: CeStatS, Advanced Mathematics Research Institute, UMR 7501, Strasbourg University and CNRS, Strasbourg, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Poulin
authors.affiliation: Division of Medical Physics, Department of Radiotherapy, Paul Strauss Center, Strasbourg, France.
authors.forename: Diran
authors.initials: D
authors.lastname: Karamanoukian
mesh_terms: D001940:Breast / Q000473:pathology / Q000528:radiation effects*; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D062485:Breath Holding; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008168:Lung / Q000528:radiation effects*; D008875:Middle Aged; D058958:Organs at Risk; D056888:Patient Positioning; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012119:Respiration; D014018:Tissue Distribution
keywords: Breast cancer; Deep inspiration breath-hold; Heart sparing; Radiotherapy; TomoDirect