Direct measurement of absorbed dose to water in HDR 192Ir brachytherapy: water calorimetry, ionization chamber, Gafchromic film, and TG-43

Download
  1. Get@NRC: Direct measurement of absorbed dose to water in HDR 192Ir brachytherapy: water calorimetry, ionization chamber, Gafchromic film, and TG-43 (Opens in a new window)
DOIResolve DOI: http://doi.org/10.1118/1.3352685
AuthorSearch for: ; Search for: ; Search for:
TypeArticle
Journal titleMedical Physics
Volume37
Issue4
Pages19241932; # of pages: 9
SubjectHDR; 192Ir brachytherapy; dosimetry; absorbed dose; TG-43; ionometry; Gafchromic film dosimetry; water calorimetry
AbstractPurpose: Gafchromic film and ionometric calibration procedures for HDR 192Ir brachytherapy sources in terms of dose rate to water are presented and the experimental results are compared to the TG-43 protocol as well as with the absolute dose measurement results from a water calorimetry-based primary standard. Methods: EBT-1 Gafchromic films, an A1SL Exradin miniature Shonka thimble type chamber, and an SI HDR 1000 Plus well-type chamber (Standard Imaging, Inc., Middleton, WI) with an ADCL traceable Sk calibration coefficient (following the AAPM TG-43 protocol) were used. The Farmer chamber and Gafchromic film measurements were performed directly in water. All results were compared to direct and absolute absorbed dose to water measurements from a 4 °C stagnant water calorimeter. Results: Based on water calorimetry, the authors measured the dose rate to water to be 361±7 μGy/(h U) at a 55 mm source-to-detector separation. The dose rate normalized to air-kerma strength for all the techniques agree with the water calorimetry results to within 0.83%. The overall 1-sigma uncertainty on water calorimetry, ionization chamber, Gafchromic film, and TG-43 dose rate measurement amounts to 1.90%, 1.44%, 1.78%, and 2.50%, respectively. Conclusions: This work allows us to build a more realistic uncertainty estimate for absorbed dose to water determination using the TG-43 protocol. Furthermore, it provides the framework necessary for a shift from indirect HDR 192Ir brachytherapy dosimetry to a more accurate, direct, and absolute measurement of absorbed dose to water.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); NRC Institute for National Measurement Standards
Peer reviewedYes
NPARC number16378393
Export citationExport as RIS
Report a correctionReport a correction
Record identifierc08a713f-3d96-4051-a25a-86cda1a61e78
Record created2010-11-15
Record modified2016-05-09
Bookmark and share
  • Share this page with Facebook (Opens in a new window)
  • Share this page with Twitter (Opens in a new window)
  • Share this page with Google+ (Opens in a new window)
  • Share this page with Delicious (Opens in a new window)