Prospects for quantitative two-dimensional radiochromic film dosimetry for low dose-rate brachytherapy sources Journal Article


Authors: Le, Y.; Ali, I.; Dempsey, J. F.; Williamson, J. F.
Article Title: Prospects for quantitative two-dimensional radiochromic film dosimetry for low dose-rate brachytherapy sources
Abstract: Radiochromic film (RCF) has been shown to be a precise and accurate two-dimensional dosimeter for acute exposure radiation fields. However, "temporal history" mismatch between calibration and brachytherapy films due to RCF dose-rate effects could introduce potentially large uncertainties in low dose-rate (LDR) brachytherapy absolute dose measurement. This article presents a quantitative evaluation of the precision and accuracy of a laser scanner-based RCF-dosimetry system and the effect of the temporal history mismatch in LDR absolute dose measurement. MD-55-2 RCF was used to measure absolute dose for a low dose-rate 137Cs brachytherapy source using both single- and double-exposure techniques. Dose-measurement accuracy was evaluated by comparing RCF to Monte Carlo photon-transport simulation. The temporal history mismatch effect was investigated by examining dependence of RCF accuracy on irradiation-to-densitometry time interval. The predictions of the empirical cumulative dose superposition model (CDSM) were compared with measurements. For the double-exposure technique, the agreement between measurement and Monte Carlo simulation was better than 4% in the 3-60 Gy dose range with measurement precisions (coverage factor k=1) of <2% and <6% for the doses greater or less than 3 Gy, respectively. The overall uncertainty (k=1) of dose rate/air-kerma strength measurements achievable by this dosimetry system for a spatial resolution of 0.1 mm is less than 4% for doses greater than 5 Gy. The measured temporal history mismatch systematic error is about 1.8% for a 48 h postexposure time when using the double exposure technique and agrees with CDSM's prediction qualitatively. This work demonstrates that the model MD-55-2 RCF detector has the potential to support quantitative dose measurements about LDR brachytherapy sources with precision and accuracy better than that of previously described dosimeters. The impacts of this work on the future use of new type of RCF were also discussed. © 2006 American Association of Physicists in Medicine.
Keywords: accuracy; calibration; radiation exposure; time factors; dose-response relationship, radiation; kinetics; dosimetry; quantitative analysis; models, statistical; brachytherapy; radiometry; radiotherapy planning, computer-assisted; radiochromic film dosimetry; film dosimetry; photons; computer model; x-ray film; monte carlo; monte carlo method; x-rays; uncertainty; low dose-rate; radiochromic film (rcf); cumulative dose superposition model; cesium radioisotopes
Journal Title: Medical Physics
Volume: 33
Issue: 12
ISSN: 0094-2405
Publisher: American Association of Physicists in Medicine  
Date Published: 2006-12-01
Start Page: 4622
End Page: 4634
Language: English
DOI: 10.1118/1.2390546
PUBMED: 17278815
PROVIDER: scopus
DOI/URL:
Notes: --- - "Cited By (since 1996): 3" - "Export Date: 4 June 2012" - "Art. No.: 031612MPH" - "CODEN: MPHYA" - "Source: Scopus"
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  1. Imad Ali
    7 Ali