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Commissioning of a well type chamber for HDR and LDR brachytherapy applications: a review of methodology and outcomes

  • Godfrey MukwadaEmail author
  • Gabor Neveri
  • Zaid Alkhatib
  • David K. Waterhouse
  • Martin Ebert
Scientific Paper

Abstract

For safe and accurate dose delivery in brachytherapy, associated equipment is subject to commissioning and ongoing quality assurance (QA). Many centres depend on the use of a well-type chamber (‘well chamber’) for performing brachytherapy dosimetry. Documentation of well chamber commissioning is scarce despite the important role the chamber plays in the whole brachytherapy QA process. An extensive and structured commissioning of the HDR 1000 plus well chamber (Standard Imaging Inc, Middleton WI) for HDR and LDR dosimetry was undertaken at Sir Charles Gairdner Hospital. The methodology and outcomes of this commissioning is documented and presented as a guideline to others involved in brachytherapy. The commissioning tests described include mechanical integrity, leakage current, directional dependence, response, length of uniform response, the influence of insert holders, ion collection efficiency, polarity effect, accuracy of measured air kerma strength (S K ) or reference air kerma rate (K R ) and baseline setting (for ongoing constancy checks). For the HDR 1000 plus well chamber, some of the insert holders modify the response curve. The measured sweet length was 2.5 cm which is within 0.5 % of that specified by the manufacturer. Correction for polarity was negligible (0.9999) and ion recombination was small (0.9994). Directional dependence was small (less than 0.2 %) and leakage current was negligible. The measured K R for 192Ir agreed within 0.11 % compared with a second well chamber of similar model and was within 0.5 % of that determined via a free-in-air measurement method. Routine constancy checks over a year agreed with the baseline within 0.4 %.

Keywords

Well type chamber (well chamber) Brachytherapy HDR LDR Commissioning Reference air kerma rate 

Notes

Acknowledgments

The authors would like to acknowledge assistance from fellow Medical Physicists at Sir Charles Gairdner Hospital. We would like to thank the hospital for the facility and environment that is conducive for such endeavours.

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Copyright information

© Australasian College of Physical Scientists and Engineers in Medicine 2015

Authors and Affiliations

  • Godfrey Mukwada
    • 1
    Email author
  • Gabor Neveri
    • 1
  • Zaid Alkhatib
    • 1
  • David K. Waterhouse
    • 1
  • Martin Ebert
    • 1
    • 2
  1. 1.Radiation Oncology DepartmentSir Charles Gairdner HospitalNedlandsAustralia
  2. 2.School of PhysicsUniversity of Western AustraliaCrawleyAustralia

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