Dose Reduction Techniques in Cardiac CT Ensuring That Patients Are Receiving Quality Cardiac CT Studies, at Minimum Risk

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Multi-detector computed tomography (MDCT) is becoming a standard tool for the detection of cardiac disease. In many practices, computed tomography (CT) is the preferred test for coronary plaque imaging, anatomic visualization and stenosis detection which may lead to anti-atherosclerotic therapies. However, as with other diagnostic imaging studies that use radiation, the diagnostic benefit that the test provides must compensate for the radiation dose that the patient receives.

Operators and physicians must be knowledgeable of the factors that contribute to patient dose and receive appropriate training on their specific CT unit. Optimization of protocol selection to keep patient exposure low while maintaining diagnostic quality of the examination is a balance that must be achieved. An examination which is non-diagnostic, exposes the patient to radiation without benefit. There are parameters that the technologist can employ such as prospective gating, tube current reduction or minimizing the field of view that are based on the patient habitus and cardiac rhythm. Careful attention to detail of the CT acquisition is crucial to finding the balance between image quality and radiation exposure.

The use of computed tomography angiography (CTA) to visualize the coronary arteries has increased dramatically over the past decade. The technological advances in multi–detector CT systems have resulted in faster scanning acquisitions which reduces motion artifacts and decreases image noise. This technology has also improved the spatial resolution in the z-axis which decreases volume effects and increases the accuracy of diagnosing vessel disease.¹ As well, thinner slices allow for higher quality multi-planer reconstructions and isotropic imaging to aid in the interpretation.

There are several effective ways to reduce patient dose while maintaining diagnostic quality. The operator must be knowledgeable of these various techniques and apply those that are appropriate given the patient’s condition, the specific CT scanner used and the clinical indication leading to the performance of the CT examination.

Summarized in this article, are the parameters that may be implemented to reduce patient dose during a cardiac CT examination, however with the exception of the first two items these techniques can be applied to all CT imaging to reduce patient dose. For complete details on the techniques described, please refer to the references by clicking on the references link at the bottom of the page.

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