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Computed tomography dose index and dose length product for cone-beam CT: Monte Carlo simulations.

Publication ,  Journal Article
Kim, S; Song, H; Samei, E; Yin, F-F; Yoshizumi, TT
Published in: J Appl Clin Med Phys
January 19, 2011

Dosimetry in kilovoltage cone beam computed tomography (CBCT) is a challenge due to the limitation of physical measurements. To address this, we used a Monte Carlo (MC) method to estimate the CT dose index (CTDI) and the dose length product (DLP) for a commercial CBCT system. As Dixon and Boone showed that CTDI concept can be applicable to both CBCT and conventional CT, we evaluated weighted CT dose index (CTDI(w)) and DLP for a commercial CBCT system. Two extended CT phantoms were created in our BEAMnrc/EGSnrc MC system. Before the simulations, the beam collimation of a Varian On-Board Imager (OBI) system was measured with radiochromic films (model: XR-QA). The MC model of the OBI X-ray tube, validated in a previous study, was used to acquire the phase space files of the full-fan and half-fan cone beams. Then, DOSXYZnrc user code simulated a total of 20 CBCT scans for the nominal beam widths from 1 cm to 10 cm. After the simulations, CBCT dose profiles at center and peripheral locations were extracted and integrated (dose profile integral, DPI) to calculate the CTDI per each beam width. The weighted cone-beam CTDI (CTDI(w,l)) was calculated from DPI values and mean CTDI(w,l) (CTDI(w,l)) and DLP were derived. We also evaluated the differences of CTDI(w) values between MC simulations and point dose measurements using standard CT phantoms. In results, it was found that CTDI(w,600) was 8.74 ± 0.01 cGy for head and CTDI(w,900) was 4.26 ± 0.01 cGy for body scan. The DLP was found to be proportional to the beam collimation. We also found that the point dose measurements with standard CT phantoms can estimate the CTDI within 3% difference compared to the full integrated CTDI from the MC method. This study showed the usability of CTDI as a dose index and DLP as a total dose descriptor in CBCT scans.

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Published In

J Appl Clin Med Phys

DOI

EISSN

1526-9914

Publication Date

January 19, 2011

Volume

12

Issue

2

Start / End Page

3395

Location

United States

Related Subject Headings

  • Tomography, X-Ray Computed
  • Radiometry
  • Radiation Dosage
  • Phantoms, Imaging
  • Nuclear Medicine & Medical Imaging
  • Monte Carlo Method
  • Models, Statistical
  • Humans
  • Film Dosimetry
  • Equipment Design
 

Citation

APA
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MLA
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Kim, S., Song, H., Samei, E., Yin, F.-F., & Yoshizumi, T. T. (2011). Computed tomography dose index and dose length product for cone-beam CT: Monte Carlo simulations. J Appl Clin Med Phys, 12(2), 3395. https://doi.org/10.1120/jacmp.v12i2.3395
Kim, Sangroh, Haijun Song, Ehsan Samei, Fang-Fang Yin, and Terry T. Yoshizumi. “Computed tomography dose index and dose length product for cone-beam CT: Monte Carlo simulations.J Appl Clin Med Phys 12, no. 2 (January 19, 2011): 3395. https://doi.org/10.1120/jacmp.v12i2.3395.
Kim S, Song H, Samei E, Yin F-F, Yoshizumi TT. Computed tomography dose index and dose length product for cone-beam CT: Monte Carlo simulations. J Appl Clin Med Phys. 2011 Jan 19;12(2):3395.
Kim, Sangroh, et al. “Computed tomography dose index and dose length product for cone-beam CT: Monte Carlo simulations.J Appl Clin Med Phys, vol. 12, no. 2, Jan. 2011, p. 3395. Pubmed, doi:10.1120/jacmp.v12i2.3395.
Kim S, Song H, Samei E, Yin F-F, Yoshizumi TT. Computed tomography dose index and dose length product for cone-beam CT: Monte Carlo simulations. J Appl Clin Med Phys. 2011 Jan 19;12(2):3395.

Published In

J Appl Clin Med Phys

DOI

EISSN

1526-9914

Publication Date

January 19, 2011

Volume

12

Issue

2

Start / End Page

3395

Location

United States

Related Subject Headings

  • Tomography, X-Ray Computed
  • Radiometry
  • Radiation Dosage
  • Phantoms, Imaging
  • Nuclear Medicine & Medical Imaging
  • Monte Carlo Method
  • Models, Statistical
  • Humans
  • Film Dosimetry
  • Equipment Design