Author + information
- Received January 3, 2017
- Revision received May 26, 2017
- Accepted June 5, 2017
- Published online January 1, 2018.
- Sigal Trattner, PhDa,
- Sandra Halliburton, PhDb,
- Carla M. Thompson, PhDc,
- Yanping Xu, PhDd,
- Anjali Chelliah, MDe,
- Sachin R. Jambawalikar, PhDf,
- Boyu Peng, MSg,
- M. Robert Peters, MDh,
- Jill E. Jacobs, MDi,
- Munir Ghesani, MDj,
- James J. Jang, MDk,
- Hussein Al-Khalidi, PhDl and
- Andrew J. Einstein, MD, PhDm,∗ ()
- aDepartment of Medicine, Division of Cardiology, Columbia University Medical Center, and New York-Presbyterian Hospital, New York, New York
- bImaging Institute, Division of Radiology, Cleveland Clinic, Cleveland, Ohio, and Lerner Research Institute, Department of Biomedical Engineering, Cleveland Clinic, Cleveland, Ohio, and Department of Chemical and Biomedical Engineering, Cleveland State University, Cleveland, Ohio, and Philips Healthcare, Cleveland, Ohio
- cImaging Institute, Division of Radiology, Cleveland Clinic, and Lerner Research Institute, Department of Biomedical Engineering, Cleveland Clinic, and Department of Chemical and Biomedical Engineering, Cleveland State University, Cleveland, Ohio
- dRadiological Research Accelerator Facility, Center for Radiological Research, Columbia University Medical Center, Irvington, New York
- eDepartment of Pediatrics, Division of Pediatric Cardiology, New York-Presbyterian Morgan Stanley Children's Hospital, and Columbia University Medical Center, New York, New York
- fDepartment of Radiology, Columbia University Medical Center, and New York-Presbyterian Hospital, New York, New York
- gDepartment of Radiology, Columbia University Medical Center, and New York-Presbyterian Hospital, New York, New York
- hAdvanced Cardiovascular Imaging, New York, New York
- iSection of Cardiac Imaging, Department of Radiology, New York University School of Medicine, and New York University Langone Medical Center, New York, New York
- jDivision of Nuclear Medicine, Department of Radiology, New York University, and New York University Langone Medical Center, New York, New York
- kDivision of Cardiology, Kaiser Permanente San Jose Medical Center, San Jose, California
- lDuke Clinical Research Institute, Duke University Medical Center, Durham, North Carolina
- mDepartment of Medicine, Cardiology Division, and Department of Radiology, Columbia University Medical Center, and New York Presbyterian Hospital, New York, New York
- ↵∗Address for correspondence:
Dr. Andrew J. Einstein, Columbia University Medical Center, Department of Medicine, Division of Cardiology, 622 West 168th Street, PH 10-203B, New York, New York 10032.
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.
This study was supported by National Institutes of Health/National Heart, Lung, and Blood Institute grant R01 HL109711. Dr. Einstein is supported by Herbert Irving Associate Professorship and Victoria and Esther Aboodi Cardiology Researcher. Dr. Halliburton has received institutional research grants to Cleveland Clinic from Philips Healthcare and Siemens Healthcare; and is currently an employee of Philips Healthcare (her role in data collection and analysis was all performed as an employee of Cleveland Clinic, prior to her employment by Philips Healthcare). Dr. Peters has received institutional research grants from and served on the speakers’ bureau of Toshiba America Medical Systems. Dr. Einstein has received institutional research grants from GE Healthcare, Philips Healthcare, and Toshiba America Medical Systems. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose. Dr. Thompson’s current affiliation is Vanderbilt University, Nashville, Tennessee. Dr. Xu’s current affiliation is Department of Physics, East Carolina University, Greenville, North Carolina.
- Received January 3, 2017.
- Revision received May 26, 2017.
- Accepted June 5, 2017.
- 2018 The Authors