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KEY POINTS
Radiation exposure and outcomes: Radiationexposure to patients should be a concern in evaluating testing procedures.
Current patient radiation exposure demonstrates 12 to 15 mSv for single-photon emission computed tomography (SPECT) and 3.5 to 4.0 for positron emission tomography (PET) perfusion imaging.
Strategies for radiation reduction in SPECT MPI are described and include stress-only imaging and radiation reduction software applicable for most current cameras.
Current status of PET radiation exposure demonstrates that the common tracer, rubidium, is consistently below the American Society of Nuclear Cardiology recommendations for patient exposure.
Strategies for radiation reduction in PET MPI include 3D imaging and use of one transmission scan for attenuation correction.
Can radiation reduction strategies work? Recent studies demonstrate success in meeting more than 5 mSv per patient with current systems.
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Patient radiation exposure during medical procedures is a growing concern among healthcare providers and professional organizations, as well as the general public. Medical radiation (of all subtypes) has increased by over 700% since 1980. Because of its value in diagnosis and prognosis in patients with known or suspected obstructive coronary disease, radionuclide MPI use has also increased over the last 25 years. Nuclear imaging accounts for approximately 25% of medical radiation. Cardiac imaging represents approximately 50% of all nuclear imaging procedures but is responsible for nearly 85% of all nuclear radiation doses.1–4
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Optimizing radiation exposure for patients is of considerable importance for patient safety and should be taken into account when ordering tests. For the nuclear cardiologist, this impacts choices in testing protocols, equipment, and even tracers. Radiation-reduction strategies should also take into account the value of the testing procedure and should not be performed at the expense of image quality, and thus the value of the examination itself. This chapter will present concepts of the consequences of radiation exposure, methods of measuring radiation exposure in medical imaging, and, in particular, nuclear cardiology; describe current radiation exposure in common cardiovascular single-photon emission computed tomography (SPECT) and positron emission tomography (PET) MPI procedures; and discuss the methods of reducing radiation exposure through instrumentation changes, protocol changes, and tracer choice.
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Radiation Exposure: The Data
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The exact consequences of radiation exposure are uncertain. The deterministic effects of direct radiation to an organ system, such as epidermal reactions, are well studied. However, understanding the consequences of radiation exposure to an individual is more obscure and difficult to assess. These stochastic effects of radiation exposure acquired during medical imaging are indeed difficult to apply to an individual’s lifetime risk of developing cancers. This is in part due to variations in radiation types, exposure rates and quantities, and tissue susceptibilities, as well as timing of procedures. In addition, malignancy generated by radiation exposure is often indistinguishable from those occurring from other causes.2 Data estimated from the coronary computed tomography (CT) literature suggest that a 10-mSv radiation exposure increases lifetime risk of developing ...