Radiation Dose and Safety in Cardiac Computed Tomography

Abstract

SynopsisAs a result of the changes in utilization of imaging procedures that rely on ionizing radiation, the collective dose has increased by over 700% and the annual per-capita dose, by almost 600% over recent years. It is certainly possible that this growing use may have significant effects on public health. Although there are uncertainties related to the accuracy of calculated radiation exposure and the estimated biologic risk, there are measures that can be taken to reduce any potential risks while maintaining diagnostic accuracy. This article will review the existing data regarding biological hazards of radiation exposure associated to medical diagnostic testing, the methodology used to estimate radiation exposure and the measures that can be taken to effectively reduce it. IntroductionIn recent years, reports on radiation exposure resulting from medical imaging have unfailingly attracted intense attention by the media, whose reporting typically emphasizes the risks of such exposure. It is certainly possible that the growing use of imaging procedures that rely on ionizing radiation may have significant effects on public health. However, the potential health risks of ionizing radiation at the levels used in medical imaging are rarely portrayed in a balanced fashion that would highlight the patterns of use of medical imaging, the uncertainties about the magnitude of risk of cancer, or the undeniable benefits of medical imaging in specific scenarios. The purpose of this review is to provide an understanding of 1. the strengths and shortcomings of epidemiologic evaluations of radiation exposure to the general population, 2. the uncertainties related to radiation dosimetry and estimating the biologic risk (including carcinogenesis) resulting from exposure to ionizing radiation, and 3. the measures that can be taken to maximize our opportunities to perform the right study in the right patient with a radiation dose that is as low as reasonably achievable. In keeping with the main theme of the current issue of Cardiology Clinics, our review will focus on cardiac CT imaging in adults.Address for Correspondence: Thomas C Gerber, M.D., Ph.D., Associate Professor of Medicine and Radiology, Division of Cardiovascular Diseases, Mayo Clinic, 4500 San Pablo Road, Jacksonville, Florida 32224, gerber.thomas@mayo.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Taken together, the estimated 67 million CT (computed tomography) and 19 million nuclear medicine studies performed in 2006 accounted for 22% of imaging procedures that used ionizing radiation but 75% of the collective E (ex...

Iterative reconstruction in image space (IRIS) in cardiac computed tomography: initial experience

“…For this reason, several new image acquisition and reconstruction protocols have been developed. Among those, ECG-based tube current modulation, prospectively ECG-triggered acquisition, and reduction of tube voltage are among the most commonly used [6]. Tube current correlates to dose in a linear fashion and hence, reductions of the tube current lead to lower radiation dose values.…”

Computed Tomographic Coronary Artery Calcium Assessment for Evaluating Chest Pain in the Emergency Department: Long-term Outcome of a Prospective Blind Study

“…Stress/ rest technetium Tc 99m sestamibi myocardial perfusion imaging exposes the patient to 9 mSv; diagnostic invasive cardiac angiography, to 7 mSv; conventional chest CT, to 7 mSv; and chest radiography, to 0.1 mSv. 44 A cardiac CT CAC assessment performed by MDCT exposes the patient to an effective radiation dose of 1 to 3 mSv, depending on the type of gating used. 44,45 A CAC determination by electron beam CT exposes the patient to 1 mSv.…”

“…44 A cardiac CT CAC assessment performed by MDCT exposes the patient to an effective radiation dose of 1 to 3 mSv, depending on the type of gating used. 44,45 A CAC determination by electron beam CT exposes the patient to 1 mSv. 45 Current standard cardiac CTA protocols expose women to an effective dose of 21 mSv and men to 15 mSv.…”

Established and emerging dose reduction methods in cardiac computed tomography

“…14 Malignancy is thought to be an example of a stochastic effect produced from ionising radiation. 15 …”