Influence of difference in cross-sectional dose profile in a CTDI phantom on X-ray CT dose estimation: A Monte Carlo study

Tomonobu Haba, Shuji Koyama, Yoshihiro Ida

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

The longitudinal dose profile in a computed tomography dose index (CTDI) phantom had been studied by many researchers. The cross-sectional dose profile in the CTDI phantom, however, has not been studied. It is also important to understand the cross-sectional dose profile in the CTDI phantom for dose estimation in X-ray CT. In this study, the cross-sectional dose profile in the CTDI phantom was calculated by use of a Monte Carlo (MC) simulation method. A helical or a 320-detector-row cone-beam X-ray CT scanner was simulated. The cross-sectional dose profile in the CTDI phantom from surface to surface through the center point was calculated by MC simulation. The shape of the calculation region was a cylinder of 1-mm-diameter. The length of the cylinder was 23, 100, or 300 mm to represent various CT ionization chamber lengths. Detailed analyses of the energy depositions demonstrated that the cross-sectional dose profile was different in measurement methods and phantom sizes. In this study, we also focused on the validation of the weighting factor used in weighted CTDI (CTDIw). As it stands now, the weighting factor used in CTDI w is (1/3, 2/3) for the (central, peripheral) axes. Our results showed that an equal weighting factor, which is (1/2, 1/2) for the (central, peripheral) axes, is more suitable to estimate the average cross-sectional dose when X-ray CT dose estimation is performed.

Original languageEnglish
Pages (from-to)133-140
Number of pages8
JournalRadiological Physics and Technology
Volume7
Issue number1
DOIs
Publication statusPublished - 01-2014

All Science Journal Classification (ASJC) codes

  • Radiation
  • Physical Therapy, Sports Therapy and Rehabilitation
  • Radiology Nuclear Medicine and imaging

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