title: In vivo surface dose measurement using GafChromic film dosimetry in breast cancer radiotherapy: comparison of 7-field IMRT, tangential IMRT and tangential 3D-CRT.
abstract: OBJECTIVE
  The purpose of this study was to compare the surface dose of 7-field IMRT (7 F-IMRT), tangential beam IMRT (TB-IMRT), and tangential beam 3D-CRT (3D-CRT) of breast cancer patients receiving adjuvant radiotherapy by means of in vivo GafChromic film dosimetry.
  
  
  METHODS
  Breast cancer patients receiving adjuvant radiotherapy of the whole breast or the chest wall were eligible for the study. Study patients were treated with a treatment plan using two different radiotherapy techniques (first patient series, 3D-CRT followed by TB-IMRT; second patient series, TB-IMRT followed by 7 F-IMRT). The surface dose was evaluated on three consecutive treatment fractions per radiotherapy technique using in vivo GafChromic film dosimetry. The paired t-test was used to assess the difference of in vivo GafChromic film readings or calculated plan parameters of the compared pairs of radiation techniques for statistical significance.
  
  
  RESULTS
  Forty-five unselected breast cancer patients were analysed in this study. 7 F-IMRT significantly reduced the surface dose compared to TB-IMRT. Differences were greatest in the central and lateral breast or chest wall region and amounted to a dose reduction of -11.8% to -18.8%. No significant difference of the surface dose was observed between TB-IMRT and 3D-CRT. A corresponding observation was obtained for the calculated skin dose derived from dose-volume histograms.
  
  
  CONCLUSIONS
  In adjuvant breast cancer radiotherapy, 7 F-IMRT offers a significantly reduced surface dose compared to TB-IMRT or 3D-CRT.
authors.affiliation: Department of Radiation Oncology, Saad Specialist Hospital, P,O, Box 30353, Al Khobar 31952, Saudi Arabia. VRudat@saadmedical.com.
authors.forename: Volker
authors.initials: V
authors.lastname: Rudat
authors.forename: Alaa
authors.initials: A
authors.lastname: Nour
authors.forename: Abdul Aziz
authors.initials: AA
authors.lastname: Alaradi
authors.forename: Adel
authors.initials: A
authors.lastname: Mohamed
authors.forename: Saleh
authors.initials: S
authors.lastname: Altuwaijri
mesh_terms: D001943:Breast Neoplasms / Q000532:radiotherapy*; D005260:Female; D005373:Film Dosimetry / Q000295:instrumentation* / Q000379:methods*; D005500:Follow-Up Studies; D006801:Humans; D058958:Organs at Risk; D011379:Prognosis; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D018714:Radiotherapy, Adjuvant; D020266:Radiotherapy, Conformal / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D035441:Thoracic Wall / Q000528:radiation effects*