title: [Quality control of dosing delivered by in vivo measurements for head and neck radiotherapy].
abstract: OBJECTIVE
  Measurement of absorbed dose in target volume is widely considered to be an important tool for quality assurance in external radiotherapy. The aims of this work were to measure the entrance dose for patient treated for head and neck tumors and to compare this measured dose with the dose calculated.
  
  
  METHODS
  Twenty patients were evaluated. Initially, the measurements were performed on a polystyrene phantom in order to calibrate diodes in terms of entrance dose and to determinate appropriate correction factors. In vivo entrance dosimetry check was performed for these patients treated for head and neck tumors in (60)Co gamma-rays.
  
  
  RESULTS
  For the entrance dose evaluation over 100 field measurements, the mean deviation between the measured dose and the calculated dose was equal to 0.12% and the standard deviation was 1.84%. The deviation was less than 3% in 95% of measurements. Large deviation (more than 5%) was observed in one case.
  
  
  CONCLUSIONS
  Simple in vivo dose measurements are an additional safeguard against major set-up errors and calculation or transcription errors that were missed during pretreatment chart check.
authors.affiliation: CHU Habib-Bourguiba, Sfax, Tunisie. leilafarhat2002@yahoo.fr
authors.forename: L
authors.initials: L
authors.lastname: Farhat
authors.forename: M
authors.initials: M
authors.lastname: Besbes
authors.forename: A
authors.initials: A
authors.lastname: Bridier
authors.forename: F
authors.initials: F
authors.lastname: Kaffel
authors.forename: J
authors.initials: J
authors.lastname: Daoud
mesh_terms: D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D011786:Quality Control; D011829:Radiation Dosage; D011874:Radiometry / Q000592:standards*