The Adaptive Iterative Dose Reduction algorithm AIDR 3D shows potential to reduce dose exposure by approximately 80% in comparison with the dose currently applied with FBP image processing. On the basis of phantom evaluation, a target noise of 20 HU for the application of this method in coronary calcium scanning is recommended to avoid loss in accuracy.

With iterative reconstruction using AIDR 3D, deviations of the total Agatston and volume scores remain within 4% of the reference protocol. The 1 mm inserts were detected as calcification, but scores less than ten tend to be underestimated. Following the calibration process, the application of IR in combination with reduced tube voltages allows up to 76% lower radiation dose.

A clear mathematical relationship exists between object diameter and reduction in measured CT number in HU. This function is independent of exposure parameters and inherent attenuation properties of the objects studied. Future developments include the incorporation of this mathematical model function into quantification software in order to automatically generate a true assessment of measured CT number (HU) corresponding to plaque physical density rho (g/cm(3)). This is a significant development for the accurate, noninvasive classification of noncalcified arterial plaque.

• Image quality and radiation dose are closely related in CT coronary angiography. • So too are the image quality, radiation dose and body mass index (BMI). • An image-noise-based CTCA protocol reduces the radiation dose by 25 %. • It improves inter-patient image homogeneity by 32 %.