How to reduce the radiation burden in cardiac CT

The introduction of multidetector computed tomography coronary angiography (MDCT-CA) in the late 90s has allowed a non-invasive evaluation of coronary artery anatomy, representing a promising alternative to invasive coronary angiography to rule out coronary artery disease in patients with low to intermediate risk with disagreement between symptoms and functional stress tests findings. In unknown unascertained dilated cardiomyopathy and to evaluate the coronary artery bypass graft and stent patency. However, because a trade-off between image noise and image quality occurs, a higher radiation exposure needs to be taken in account to maintain an adequate image quality. Therefore, due to the impressive MDCT number increase, the annual per capita radiation dose has increased from 0.53 to 3 mSv that is close to the natural radiation background with almost half dose derived from MDCT. Several strategies to minimize radiation dose has have been recently developed such as scan length optimization, tube voltage and tube current reduction, tube current modulation ECG-triggered, dual source MDCT, prospective ECG-triggering, a higher number of slices, the use of adaptive statistical iterative reconstruction algorithm and high pitch MDCT-CA. The aim of the chapter is to define overall radiological risk of MDCT-CA in clinical practice and to assess the protocol strategy to minimize the overall radiation exposure of the patients according to the ALARA principle (as low as reasonably achievable).