title: Dosimetric Effects of the Interfraction Variations during Whole Breast Radiotherapy: A Prospective Study.
abstract: BACKGROUND
  The aim of this work was to assess the dosimetric impact of the interfraction variations during breast radiotherapy.
  
  
  METHODS
  Daily portal imaging measurements were prospectively performed in 10 patients treated with adjuvant whole breast irradiation (50 Gy/25 fractions). Margins between the clinical target volume and the planning target volume (PTV) were 5 mm in the three dimensions. Parameters of interest were the central lung distance (CLD) and the inferior central margin (ICM). Daily movements were applied to the baseline treatment planning (TP1) to design a further TP (TP2). The PTV coverage and organ at risk exposure were measured on both TP1 and TP2, before being compared.
  
  
  RESULTS
  A total of 241 portal images were analyzed. The random and systematic errors were 2.6 and 3.7 mm for the CLD, 4.3 and 6.9 mm for the ICM, respectively. No significant consequence on the PTV treatments was observed (mean variations: +0.1%, p = 0.56 and -1.8%, p = 0.08 for the breast and the tumor bed, respectively). The ipsilateral lung and heart exposure was not significantly modified.
  
  
  CONCLUSIONS
  In our series, the daily interfraction variations had no significant effect on the PTV coverage or healthy tissue exposure during breast radiotherapy.
authors.affiliation: Department of Radiotherapy, Gustave Roussy , Villejuif , France.
authors.forename: Julian
authors.initials: J
authors.lastname: Jacob
authors.affiliation: Department of Radiotherapy, Gustave Roussy , Villejuif , France.
authors.forename: Steve
authors.initials: S
authors.lastname: Heymann
authors.affiliation: Department of Biostatistics and Epidemiology, Gustave Roussy , Villejuif , France ; University Paris-Sud , Kremlin-Bicêtre , France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Borget
authors.affiliation: Department of Physics, Gustave Roussy , Villejuif , France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Dumas
authors.affiliation: Department of Physics, Gustave Roussy , Villejuif , France.
authors.forename: Elyes
authors.initials: E
authors.lastname: Riahi
authors.affiliation: Department of Radiotherapy, Gustave Roussy , Villejuif , France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Maroun
authors.affiliation: Department of Radiotherapy, Gustave Roussy , Villejuif , France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Ezra
authors.affiliation: Department of Radiotherapy, Gustave Roussy , Villejuif , France.
authors.forename: Elena
authors.initials: E
authors.lastname: Roberti
authors.affiliation: Department of Radiotherapy, Gustave Roussy , Villejuif , France.
authors.forename: Sofia
authors.initials: S
authors.lastname: Rivera
authors.affiliation: Department of Radiotherapy, Gustave Roussy , Villejuif , France ; University Paris-Sud , Kremlin-Bicêtre , France.
authors.forename: Eric
authors.initials: E
authors.lastname: Deutsch
authors.affiliation: Department of Oncologic Radiotherapy, Institut du Cancer de Montpellier , Montpellier , France.
authors.forename: Céline
authors.initials: C
authors.lastname: Bourgier
keywords: breast radiotherapy; central lung distance; dosimetry; inferior central margin; interfraction variations