title: A multicentre 'end to end' dosimetry audit for cervix HDR brachytherapy treatment.
abstract: OBJECTIVE
  To undertake the first multicentre fully 'end to end' dosimetry audit for HDR cervix brachytherapy, comparing planned and delivered dose distributions around clinical treatment applicators, with review of local procedures.
  
  
  METHODS
  A film-dosimetry audit was performed at 46 centres, including imaging, applicator reconstruction, treatment planning and delivery. Film dose maps were calculated using triple-channel dosimetry and compared to RTDose data from treatment planning systems. Deviations between plan and measurement were quantified at prescription Point A and using gamma analysis. Local procedures were also discussed.
  
  
  RESULTS
  The mean difference between planned and measured dose at Point A was -0.6% for plastic applicators and -3.0% for metal applicators, at standard uncertainty 3.0% (k=1). Isodose distributions agreed within 1mm over a dose range 2-16Gy. Mean gamma passing rates exceeded 97% for plastic and metal applicators at 3% (local) 2mm criteria. Two errors were found: one dose normalisation error and one applicator library misaligned with the imaged applicator. Suggestions for quality improvement were also made.
  
  
  CONCLUSIONS
  The concept of 'end to end' dosimetry audit for HDR brachytherapy has been successfully implemented in a multicentre environment, providing evidence that a high level of accuracy in brachytherapy dosimetry can be achieved.
authors.affiliation: Portsmouth Hospitals NHS Trust, Portsmouth, UK; University of Surrey, Guildford, UK; IPEM RT-SIG Brachytherapy Audit Working Party, UK. Electronic address: antony.palmer@porthosp.nhs.uk.
authors.forename: Antony L
authors.initials: AL
authors.lastname: Palmer
authors.affiliation: IPEM RT-SIG Brachytherapy Audit Working Party, UK; Radiotherapy Trials Quality Assurance Group, Mount Vernon Cancer Centre, UK.
authors.forename: Patricia
authors.initials: P
authors.lastname: Diez
authors.affiliation: IPEM RT-SIG Brachytherapy Audit Working Party, UK.
authors.forename: Laura
authors.initials: L
authors.lastname: Gandon
authors.affiliation: IPEM RT-SIG Brachytherapy Audit Working Party, UK.
authors.forename: Andrea
authors.initials: A
authors.lastname: Wynn-Jones
authors.affiliation: IPEM RT-SIG Brachytherapy Audit Working Party, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Bownes
authors.affiliation: IPEM RT-SIG Brachytherapy Audit Working Party, UK.
authors.forename: Chris
authors.initials: C
authors.lastname: Lee
authors.affiliation: IPEM RT-SIG Brachytherapy Audit Working Party, UK; Radiotherapy Trials Quality Assurance Group, Mount Vernon Cancer Centre, UK.
authors.forename: Edwin
authors.initials: E
authors.lastname: Aird
authors.affiliation: IPEM RT-SIG Brachytherapy Audit Working Party, UK.
authors.forename: Margaret
authors.initials: M
authors.lastname: Bidmead
authors.affiliation: IPEM RT-SIG Brachytherapy Audit Working Party, UK.
authors.forename: Gerry
authors.initials: G
authors.lastname: Lowe
authors.affiliation: University of Surrey, Guildford, UK.
authors.forename: David
authors.initials: D
authors.lastname: Bradley
authors.affiliation: University of Surrey, Guildford, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Nisbet
mesh_terms: D001918:Brachytherapy / Q000379:methods* / Q000592:standards; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005373:Film Dosimetry / Q000379:methods* / Q000592:standards; D006801:Humans; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D035501:Uncertainty; D002583:Uterine Cervical Neoplasms / Q000532:radiotherapy*
keywords: Audit; Brachytherapy; Dosimetry; HDR; Process; Quality assurance