New approaches to reduce radiation exposure

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Abstract

Exposure to ionizing radiation is associated with a long-term risk of health effects, including cancer. Radiation exposure to the U.S. population from cardiac imaging has increased markedly over the past three decades. Initiatives to reduce radiation exposure have focused on the tenets of appropriate study “justification” and “optimization” of imaging protocols. This article reviews ways to optimally reduce radiation dose across the spectrum of cardiac imaging.

Introduction

Over the preceding three decades, the U.S. population has seen an estimated sevenfold increase in annual medical imaging ionizing radiation exposure [1]. Cardiac imaging procedures are a major contributor to population radiation exposure in the U.S., collectively accounting for nearly one-fifth of the cumulative radiation dose and approximately 40% of the cumulative dose from medical imaging procedures (Fig. 1) [1], [2], [3]. In its 2007 report, the International Commission on Radiologic Protection (ICRP) noted that cardiologists frequently receive inadequate training in radiation protection [4]. Fortunately, this is beginning to change and an increased focus on radiation safety by the cardiology community has led to advances in technology, imaging protocols, and the development of appropriate use criteria to limit radiation exposure. The purpose of this article is to provide an overview of ionizing radiation during medical imaging, including dosing metrics, risk estimation, and strategies to reduce dose and/or mitigate radiation risk during cardiovascular procedures.

Section snippets

How is radiation dose measured?

Radiation dose is a complex topic and there are a slew of different measures that quantify various aspects of radiation (Table 1). Fig. 2 demonstrates how some of these different dose measures used during fluoroscopy will vary depending on the various aspects of radiation dose that are being evaluated. Similarly for other imaging modalities, including CT and nuclear medicine scans, different metrics might be useful depending on the dosing scenario. This review focuses largely on the long-term

How much radiation from medical imaging?

Effective dose is typically reported in units of millisieverts (mSv). In its 2009 report, the National Council on Radiation Protection (NCRP) estimated an average annual exposure to an individual in the U.S. of 6.2 mSv [1], approximately half from medical imaging procedures with the other half from background sources, predominantly radon [5]. For a frame of reference, a single antero-posterior chest radiograph typically requires 0.02 mSv of effective dose. Fig. 2 demonstrates estimated

What is the risk to patients?

Ionizing radiation involves charged particles containing enough energy to displace electrons and break chemical bonds [7]. Any cell or molecule can be damaged; however, this review is primarily focused on the long-term risk of stochastic effects, most importantly iatrogenic cancer. Cancer is believed to result from misrepair of DNA damage. The extent of DNA damage is proportional to the ionizing radiation exposure and this mechanistic relationship underlies the linear, no threshold model of

Are certain populations at increased risk?

On the basis of epidemiologic studies, combined with mathematical modeling, basic science data, and expert consensus, a series of National Academy of Sciences committees on the biological effects of ionizing radiation (known by the acronym BEIR) have published cancer risk estimates for males and females based on age at exposure [7]. The most recent BEIR risk estimates highlight the substantially increased risk to females due to the risk of breast cancer, and to the young due to the increased

How to reduce radiation burden during cardiac imaging?

The principles of justification and optimization form the backbone of medical imaging dose reduction recommendations [2]. Justification means that a medical procedure should be performed only when the anticipated clinical benefits exceed all anticipated risks, including radiation risk. For individual patients the long-term risks associated with radiation exposure are extremely low. Nonetheless, according to established appropriate use criteria [16], [17], [18], a significant percentage (from

Conclusions and future directions

For the foreseeable future, procedures involving ionizing radiation will remain a vital part of cardiovascular practice; despite the great benefits of these procedures, there are inherent risks to patients and the estimated public health burden is substantial. Therefore, the cardiology community must continue to strive to minimize radiation burden but without compromising diagnostic accuracy or procedural safety. Immediate gains are achievable with improved study justification and by optimizing

Acknowledgments

The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or other funding groups.

References (46)

  • W.G. Weigold et al.

    Standardized medical terminology for cardiac computed tomography: a report of the Society of Cardiovascular Computed Tomography

    J Cardiovasc Comput Tomogr

    (2011)
  • S.S. Halliburton et al.

    SCCT guidelines on radiation dose and dose-optimization strategies in cardiovascular CT

    J Cardiovasc Comput Tomogr

    (2011)
  • J. Hausleiter et al.

    Image quality and radiation exposure with prospectively ECG-triggered axial scanning for coronary CT angiography: the multicenter, multivendor, randomized PROTECTION-III study

    JACC Cardiovasc Imaging

    (2012)
  • M.D. Cerqueira et al.

    Recommendations for reducing radiation exposure in myocardial perfusion imaging

    J Nucl Cardiol

    (2010)
  • E.G. Depuey et al.

    Patient-centered imaging

    J Nucl Cardiol

    (2012)
  • E.G. DePuey

    Advances in SPECT camera software and hardware: currently available and new on the horizon

    J Nucl Cardiol

    (2012)
  • E.G. DePuey et al.

    Very low-activity stress/high-activity rest, single-day myocardial perfusion SPECT with a conventional sodium iodide camera and wide beam reconstruction processing

    J Nucl Cardiol

    (2012)
  • P.J. Slomka et al.

    Advances in technical aspects of myocardial perfusion SPECT imaging

    J Nucl Cardiol

    (2009)
  • A.J. Einstein et al.

    Patient-centered imaging: shared decision making for cardiac imaging procedures with exposure to ionizing radiation

    J Am Coll Cardiol

    (2014)
  • National Council on Radiation Protection and Measurements

    Ionizing Radiation Exposure of the Population of the United States (NCRP report no 160)

    (2009)
  • T.C. Gerber et al.

    Ionizing radiation in cardiac imaging: a science advisory from the American Heart Association Committee on Cardiac Imaging of the Council on Clinical Cardiology and Committee on Cardiovascular Imaging and Intervention of the Council on Cardiovascular Radiology and Intervention

    Circulation

    (2009)
  • The 2007 Recommendations of the International Commission on Radiological Protection. ICRP publication 103

    Ann ICRP

    (2007)
  • D.A. Schauer et al.

    NCRP report no. 160, Ionizing Radiation Exposure of the Population of the United States, medical exposure—are we doing less with more, and is there a role for health physicists?

    Health Phys

    (2009)
  • Cited by (0)

    Dr. Hill is supported in part by Grant KL2TR001115-02 from The National Center for Advancing Translational Sciences of the National Institutes of Health, USA and a grant from the Mend A Heart Foundation. Dr. Einstein is supported in part by Grant R01 HL10971 from the National Heart Lung and Blood Institute and by a Herbert Irving Associate Professorship.

    The authors have indicated there are no conflicts of interest.

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