Size-specific dose estimates for various weighting factors of CTDI equation

Tomonobu Haba, Masanao Kobayashi, Shuji Koyama

Research output: Contribution to journalArticle

Abstract

Size-specific dose estimate (SSDE) was proposed by the American Association of Physicists in Medicine (AAPM) Task Group 204 to consider the effect of patient size in the x-ray CT dose estimation. Size correction factors to calculate SSDE were derived based on the conventional weighted CT dose index (CTDIw) equation. This study aims to investigate the influence of Bakalyar’s and the authors’ own CTDIw equations on the size correction factors described by the AAPM Task Group 204, using Monte Carlo simulations. The simulations were performed by modeling four types of x-ray CT scanner designs, to compute the dose values in water for cylindrical phantoms with 8–40 cm diameters. CTDI100 method and the AAPM Task Group 111′s proposed method were employed as the CT dosimetry models. Size correction factors were obtained for the computed dose values of various phantom diameters for the conventional, Bakalyar’s, and the authors’ weighting factors. Maximum difference between the size correction factors for the Bakalyar’s weighting factor and those of the AAPM Task Group 204 was 27% for a phantom diameter of 11.2 cm. On the other hand, the size correction factors calculated for the authors’ weighting factor were in good agreement with those from the AAPM Task Group 204 report with a maximum difference of 17%. The results indicate that the SSDE values obtained with the authors’ weighting factor can be evaluated by using the size correction factors reported by the AAPM Task Group 204, which is currently accepted as a standard.

Original languageEnglish
JournalAustralasian Physical and Engineering Sciences in Medicine
DOIs
Publication statusAccepted/In press - 01-01-2019

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Medicine
dosage
medicine
estimates
Dosimetry
X-Rays
X rays
Water
scanners
dosimeters
x rays
simulation
water

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biomedical Engineering
  • Radiology Nuclear Medicine and imaging
  • Physics and Astronomy(all)

Cite this

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title = "Size-specific dose estimates for various weighting factors of CTDI equation",
abstract = "Size-specific dose estimate (SSDE) was proposed by the American Association of Physicists in Medicine (AAPM) Task Group 204 to consider the effect of patient size in the x-ray CT dose estimation. Size correction factors to calculate SSDE were derived based on the conventional weighted CT dose index (CTDIw) equation. This study aims to investigate the influence of Bakalyar’s and the authors’ own CTDIw equations on the size correction factors described by the AAPM Task Group 204, using Monte Carlo simulations. The simulations were performed by modeling four types of x-ray CT scanner designs, to compute the dose values in water for cylindrical phantoms with 8–40 cm diameters. CTDI100 method and the AAPM Task Group 111′s proposed method were employed as the CT dosimetry models. Size correction factors were obtained for the computed dose values of various phantom diameters for the conventional, Bakalyar’s, and the authors’ weighting factors. Maximum difference between the size correction factors for the Bakalyar’s weighting factor and those of the AAPM Task Group 204 was 27{\%} for a phantom diameter of 11.2 cm. On the other hand, the size correction factors calculated for the authors’ weighting factor were in good agreement with those from the AAPM Task Group 204 report with a maximum difference of 17{\%}. The results indicate that the SSDE values obtained with the authors’ weighting factor can be evaluated by using the size correction factors reported by the AAPM Task Group 204, which is currently accepted as a standard.",
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Size-specific dose estimates for various weighting factors of CTDI equation. / Haba, Tomonobu; Kobayashi, Masanao; Koyama, Shuji.

In: Australasian Physical and Engineering Sciences in Medicine, 01.01.2019.

Research output: Contribution to journalArticle

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