Radiation Dose Optimisation of Cardiac and Vascular MDCT in Adults and Paediatric Patients

Abstract

AbstractCT Angiography (CTA) is now able to provide excellent vascular diagnosis on almost all vessels larger than 1 or 2 mm, including the coronary arteries. The radiation dose from such examinations is of concern because it may be as high as 30 mSv for cardiac CTA (CCTA). Strategies for optimising the radiation dose from CTA and CCTA are various and include the recent developments of new technologies, new software solutions, prospective ECG triggering, strict control of the heart rate, low-tube potential, tube current modulation, adaptive shielding and organ protection device. Effective dose is widely quoted in the literature but the methods used in its calculation are often inadequately documented, and poorly understood. The most common method used to calculate effective dose involves the multiplication of dose length product (DLP) by a conversion factor. However, if a different conversion factor is used this can lead to dramatic differences in the effective dose that is presented. The most common conversion factors used are the “chest” CT conversion factors published by the European Commission (0.014 or 0.017). However, these conversion factors do not take into account the 2007 changes in the ICRP tissue weighting factors and underestimate effective dose. Scanner-specific conversion factors have been calculated but are rarely used in the published literature. Here we discuss the factors required to select an appropriate conversion factor in CCTA and the importance of quoting dose length product, conversion factor and effective dose.KeywordsRadiation DoseEffective DoseConversion FactorTube VoltageDose Length ProductThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.