Use of Medical Radiation in Cardiovascular Imaging
Use of Medical Radiation in Cardiovascular Imaging
The benefits of cardiac imaging are immense, and modern medicine requires the extensive and versatile use of a variety of cardiac imaging techniques. Cardiologists are responsible for a large part of the radiation exposures every person gets per year from all medical sources. Therefore, they have a particular responsibility to avoid unjustified and non-optimized use of radiation, but sometimes are imperfectly aware of the radiological dose of the examination they prescribe or practice. This position paper aims to summarize the current knowledge on radiation effective doses (and risks) related to cardiac imaging procedures. We have reviewed the literature on radiation doses, which can range from the equivalent of 1–60 milliSievert (mSv) around a reference dose average of 15 mSv (corresponding to 750 chest X-rays) for a percutaneous coronary intervention, a cardiac radiofrequency ablation, a multidetector coronary angiography, or a myocardial perfusion imaging scintigraphy. We provide a European perspective on the best way to play an active role in implementing into clinical practice the key principle of radiation protection that: 'each patient should get the right imaging exam, at the right time, with the right radiation dose'.
Medical radiation from X-rays and nuclear medicine is the largest man-made source of radiation exposure in Western countries, and accounts for a mean effective dose (ED) of 3.0 milliSievert (mSv) per person per year, equivalent to the radiation dose of 150 chest X-rays (CXR). The natural background radiation worldwide is about 2.4 mSv (Figure 1). Cardiologists are responsible for about 40% of the entire cumulative ED to the US population from all medical sources excluding radiotherapy. In addition, the occupational radiation exposure of interventional cardiologists and cardiac electrophysiologists can be two to three times higher than that of diagnostic radiologists, and their exposure has increased steadily in the past few decades.
(Enlarge Image)
Figure 1.
Medical and natural sources of radiation per person per year. Modified from Picano and updated from Mettler et al.
The increasing use and complexity of imaging and interventional techniques have not been matched by increasing awareness and knowledge by prescribers and practitioners. The majority of doctors—including cardiologists—grossly underestimate the radiation doses for most commonly requested tests. The significant increase in the cumulative exposure of patients and population to ionizing radiation is likely to cause an increased incidence of cancer in years down the line, with an important yet potentially avoidable public health threat. Cancer induction associated with radiation goes unrecognized because it is neither differentiable nor predictable for individual patients, and because clinically significant consequences do not become evident for many years. The balance between risks and benefits determines the appropriateness score of a test: the test is appropriate when benefit greatly exceeds the risks, and inappropriate when risk exceeds the benefit. According to recent estimates, at least one-third of all cardiac examinations are partially or totally inappropriate, i.e. risks and costs outweigh benefits. The risk–benefit assessment is a 'dynamic', tailored variable rather than an absolute, fixed concept, since the same test can have a favourable risk–benefit ratio in an individual with intermediate pre-test probability and equivocal ECG, and totally inappropriate in a middle-aged woman with atypical chest pain and maximal negative ECG stress test. The order of magnitude of the risks of several imaging techniques (or associated procedures, such as stress or contrast administration) may range between 1–10% (contrast-induced nephropathy) and 0.1–0.3% (severe reaction during stress administration of dobutamine or dipyridamole). Therefore, radiation risks are certainly not the only, and probably also not the most important of the risks to be included in the risk-side of our risk–benefit assessment. However, they are probably the least well known and the least considered in our daily decision making.
Abstract and Introduction
Abstract
The benefits of cardiac imaging are immense, and modern medicine requires the extensive and versatile use of a variety of cardiac imaging techniques. Cardiologists are responsible for a large part of the radiation exposures every person gets per year from all medical sources. Therefore, they have a particular responsibility to avoid unjustified and non-optimized use of radiation, but sometimes are imperfectly aware of the radiological dose of the examination they prescribe or practice. This position paper aims to summarize the current knowledge on radiation effective doses (and risks) related to cardiac imaging procedures. We have reviewed the literature on radiation doses, which can range from the equivalent of 1–60 milliSievert (mSv) around a reference dose average of 15 mSv (corresponding to 750 chest X-rays) for a percutaneous coronary intervention, a cardiac radiofrequency ablation, a multidetector coronary angiography, or a myocardial perfusion imaging scintigraphy. We provide a European perspective on the best way to play an active role in implementing into clinical practice the key principle of radiation protection that: 'each patient should get the right imaging exam, at the right time, with the right radiation dose'.
Introduction
Medical radiation from X-rays and nuclear medicine is the largest man-made source of radiation exposure in Western countries, and accounts for a mean effective dose (ED) of 3.0 milliSievert (mSv) per person per year, equivalent to the radiation dose of 150 chest X-rays (CXR). The natural background radiation worldwide is about 2.4 mSv (Figure 1). Cardiologists are responsible for about 40% of the entire cumulative ED to the US population from all medical sources excluding radiotherapy. In addition, the occupational radiation exposure of interventional cardiologists and cardiac electrophysiologists can be two to three times higher than that of diagnostic radiologists, and their exposure has increased steadily in the past few decades.
(Enlarge Image)
Figure 1.
Medical and natural sources of radiation per person per year. Modified from Picano and updated from Mettler et al.
The increasing use and complexity of imaging and interventional techniques have not been matched by increasing awareness and knowledge by prescribers and practitioners. The majority of doctors—including cardiologists—grossly underestimate the radiation doses for most commonly requested tests. The significant increase in the cumulative exposure of patients and population to ionizing radiation is likely to cause an increased incidence of cancer in years down the line, with an important yet potentially avoidable public health threat. Cancer induction associated with radiation goes unrecognized because it is neither differentiable nor predictable for individual patients, and because clinically significant consequences do not become evident for many years. The balance between risks and benefits determines the appropriateness score of a test: the test is appropriate when benefit greatly exceeds the risks, and inappropriate when risk exceeds the benefit. According to recent estimates, at least one-third of all cardiac examinations are partially or totally inappropriate, i.e. risks and costs outweigh benefits. The risk–benefit assessment is a 'dynamic', tailored variable rather than an absolute, fixed concept, since the same test can have a favourable risk–benefit ratio in an individual with intermediate pre-test probability and equivocal ECG, and totally inappropriate in a middle-aged woman with atypical chest pain and maximal negative ECG stress test. The order of magnitude of the risks of several imaging techniques (or associated procedures, such as stress or contrast administration) may range between 1–10% (contrast-induced nephropathy) and 0.1–0.3% (severe reaction during stress administration of dobutamine or dipyridamole). Therefore, radiation risks are certainly not the only, and probably also not the most important of the risks to be included in the risk-side of our risk–benefit assessment. However, they are probably the least well known and the least considered in our daily decision making.
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