Radiation-reduction strategies in cardiac computed tomographic angiography

Abstract

KEY LEARNING OBJECTIVES: To present an in-depth analysis of dose reduction strategies in patients undergoing cardiac CT angiography (CTA). DESCRIPTION: Cardiac CTA has traditionally been associated with high radiation dose but recent technologies and acquisition techniques have allowed for significant dose reduction. Being one of the leading centres in the UK, we will share our experiences in dose reduction using real examples of diagnostic images diagrams and photographs to explain dose reduction strategies which can be classified as: ECG-linked tube current modulation: • Application of max tube current during mid-diastole (60%-80% of R-R interval). This allows dose reduction by up to 37% (stable heart rate) Prospective axial gating: • The importance of heart rate control and regularity. The merits of aggressive beta-blockade will be discussed • ‘Step and shoot’ technique with advantage of Improved resolution (z-axis) as well as drawback such as risk of step artefacts • The concept of ‘padding’ to allow for patients with tachycardia/unstable heart rate Attenuation-dependent tube modulation: • Recently, there has been a shift to modulating tube voltage (kV) from traditional value of 120kV to closer to the k-edge of iodine (80kV). This has allowed for significant dose reduction with increase in patient contrast but patient selection is important • Recent developments: • Iterative reconstruction • Garnet detector technology • High-pitch spiral acquisition CONCLUSION: Use of various strategies based on the use of new technology combined with patient factors can help in dose reduction during cardiac CTA.