A multicentre 'end to end' dosimetry audit for cervix HDR brachytherapy treatment

作者：Palmer Antony L^*; Diez Patricia; Gandon Laura; Wynn Jones Andrea; Bownes Peter; Lee Chris; Aird Edwin; Bidmead Margaret; Lowe Gerry; Bradley David; Ni**et Andrew

来源：Radiotherapy and Oncology, 2015, 114(2): 264-271.

DOI：10.1016/j.radonc.2014.12.006

• Audit
• Dosimetry
• Process
• Brachytherapy
• HDR
• Quality assurance

Purpose: 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.
Materials and 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 1 mm over a dose range 2-16 Gy. Mean gamma passing rates exceeded 97% for plastic and metal applicators at 3% (local) 2 mm 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.

• 出版日期2015-2