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Cardiac-Specific Conversion Factors to Estimate Radiation Effective Dose From Dose-Length Product in Computed Tomography.

Publication ,  Journal Article
Trattner, S; Halliburton, S; Thompson, CM; Xu, Y; Chelliah, A; Jambawalikar, SR; Peng, B; Peters, MR; Jacobs, JE; Ghesani, M; Jang, JJ ...
Published in: JACC Cardiovasc Imaging
January 2018

OBJECTIVES: This study sought to determine updated conversion factors (k-factors) that would enable accurate estimation of radiation effective dose (ED) for coronary computed tomography angiography (CTA) and calcium scoring performed on 12 contemporary scanner models and current clinical cardiac protocols and to compare these methods to the standard chest k-factor of 0.014 mSv·mGy-1cm-1. BACKGROUND: Accurate estimation of ED from cardiac CT scans is essential to meaningfully compare the benefits and risks of different cardiac imaging strategies and optimize test and protocol selection. Presently, ED from cardiac CT is generally estimated by multiplying a scanner-reported parameter, the dose-length product, by a k-factor which was determined for noncardiac chest CT, using single-slice scanners and a superseded definition of ED. METHODS: Metal-oxide-semiconductor field-effect transistor radiation detectors were positioned in organs of anthropomorphic phantoms, which were scanned using all cardiac protocols, 120 clinical protocols in total, on 12 CT scanners representing the spectrum of scanners from 5 manufacturers (GE, Hitachi, Philips, Siemens, Toshiba). Organ doses were determined for each protocol, and ED was calculated as defined in International Commission on Radiological Protection Publication 103. Effective doses and scanner-reported dose-length products were used to determine k-factors for each scanner model and protocol. RESULTS: k-Factors averaged 0.026 mSv·mGy-1cm-1 (95% confidence interval: 0.0258 to 0.0266) and ranged between 0.020 and 0.035 mSv·mGy-1cm-1. The standard chest k-factor underestimates ED by an average of 46%, ranging from 30% to 60%, depending on scanner, mode, and tube potential. Factors were higher for prospective axial versus retrospective helical scan modes, calcium scoring versus coronary CTA, and higher (100 to 120 kV) versus lower (80 kV) tube potential and varied among scanner models (range of average k-factors: 0.0229 to 0.0277 mSv·mGy-1cm-1). CONCLUSIONS: Cardiac k-factors for all scanners and protocols are considerably higher than the k-factor currently used to estimate ED of cardiac CT studies, suggesting that radiation doses from cardiac CT have been significantly and systematically underestimated. Using cardiac-specific factors can more accurately inform the benefit-risk calculus of cardiac-imaging strategies.

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Published In

JACC Cardiovasc Imaging

DOI

EISSN

1876-7591

Publication Date

January 2018

Volume

11

Issue

1

Start / End Page

64 / 74

Location

United States

Related Subject Headings

  • Vascular Calcification
  • Tomography Scanners, X-Ray Computed
  • Radiation Dosage
  • Predictive Value of Tests
  • Phantoms, Imaging
  • Humans
  • Equipment Design
  • Coronary Vessels
  • Coronary Artery Disease
  • Coronary Angiography
 

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Trattner, S., Halliburton, S., Thompson, C. M., Xu, Y., Chelliah, A., Jambawalikar, S. R., … Einstein, A. J. (2018). Cardiac-Specific Conversion Factors to Estimate Radiation Effective Dose From Dose-Length Product in Computed Tomography. JACC Cardiovasc Imaging, 11(1), 64–74. https://doi.org/10.1016/j.jcmg.2017.06.006
Trattner, Sigal, Sandra Halliburton, Carla M. Thompson, Yanping Xu, Anjali Chelliah, Sachin R. Jambawalikar, Boyu Peng, et al. “Cardiac-Specific Conversion Factors to Estimate Radiation Effective Dose From Dose-Length Product in Computed Tomography.JACC Cardiovasc Imaging 11, no. 1 (January 2018): 64–74. https://doi.org/10.1016/j.jcmg.2017.06.006.
Trattner S, Halliburton S, Thompson CM, Xu Y, Chelliah A, Jambawalikar SR, et al. Cardiac-Specific Conversion Factors to Estimate Radiation Effective Dose From Dose-Length Product in Computed Tomography. JACC Cardiovasc Imaging. 2018 Jan;11(1):64–74.
Trattner, Sigal, et al. “Cardiac-Specific Conversion Factors to Estimate Radiation Effective Dose From Dose-Length Product in Computed Tomography.JACC Cardiovasc Imaging, vol. 11, no. 1, Jan. 2018, pp. 64–74. Pubmed, doi:10.1016/j.jcmg.2017.06.006.
Trattner S, Halliburton S, Thompson CM, Xu Y, Chelliah A, Jambawalikar SR, Peng B, Peters MR, Jacobs JE, Ghesani M, Jang JJ, Al-Khalidi H, Einstein AJ. Cardiac-Specific Conversion Factors to Estimate Radiation Effective Dose From Dose-Length Product in Computed Tomography. JACC Cardiovasc Imaging. 2018 Jan;11(1):64–74.
Journal cover image

Published In

JACC Cardiovasc Imaging

DOI

EISSN

1876-7591

Publication Date

January 2018

Volume

11

Issue

1

Start / End Page

64 / 74

Location

United States

Related Subject Headings

  • Vascular Calcification
  • Tomography Scanners, X-Ray Computed
  • Radiation Dosage
  • Predictive Value of Tests
  • Phantoms, Imaging
  • Humans
  • Equipment Design
  • Coronary Vessels
  • Coronary Artery Disease
  • Coronary Angiography