![]() ![]() We will review the most current dose reduction methods used in routine clinical CCTA including prospective electrocardiogram (ECG)-gated tube current modulation, anatomy-based tube current modulation, tube voltage reduction, iterative reconstruction (IR) and heart rate reduction. Image contrast is influenced by noise, tube current and beam voltage. Temporal resolution is modified by acquisition mode, reconstruction method and gantry rotation time, while spatial resolution is modified by the detector size and configuration, focal spot size, and the reconstruction interval. A number of strategies have been developed over the last decade to optimize the trade-off between the scan parameters that affect image quality-temporal resolution, spatial resolution, and pitch-while minimizing the radiation exposure to “As Low As Reasonably Achievable” (ALARA). Given its increasing use, CCTA has thus been the key driver in developing state-of-the-art multi-slice CT over noncardiac CT imaging. However, not only is coronary angiography invasive, it requires longer examination times compared with CCTA, including patient preparation and recovery time. ![]() ![]() While the image quality produced by CCTA scanners is approaching that of the standard of reference, the mean effective radiation dose is reportedly higher for CCTA than conventional angiography in studies with directly comparable patients. Radiation doses from coronary angiography are estimated to range from 4.2 to 21.8 mSv depending on the study and vascular access site. Ĭonventionally, invasive coronary angiography is considered the gold standard for diagnosing and treating CAD. These requirements indicate that the previous high radiation doses, ranging from 18-31.4 mSv required for optimizing the image signal-to-noise ratio (SNR) in CCTA, are a major healthcare concern due to an associated increase in lifetime risk of radiation-induced malignancy. However, imaging coronary arteries presents increased challenges in CT, as it requires both high temporal resolution to reduce motion artifacts caused by the cardiac motion and a high spatial resolution to differentiate small coronary structures. Owing to its high negative predictive value, recently updated guidelines from the National Institute for Health and Clinical Excellence (NICE) on Chest Pain of Recent Onset: Assessment and Diagnosis propose using CCTA as a primary screening tool in patients with stable chest pain being assessed for possible coronary artery disease. Coronary computed tomography angiography (CCTA) is increasingly being used in the diagnosis of coronary artery disease (CAD) since it is rapid and minimally invasive. ![]()
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