Calibration of coronary calcium scores determined using iterative image reconstruction (AIDR 3D) at 120, 100, and 80 kVp.

Purpose: Computed tomography (CT) radiation dose reduction is frequently achieved by applying lower tube voltages and using iterative reconstruction (IR). For calcium scoring, the reference protocol at 120 kVp with filtered back projection (FBP) is still used, because kVp and IR may influence the Agatston score (AS) and volume score (VS). The authors present a two-step method to optimize dose: first, to determine the lowest feasible exposure and highest noise thresholds; second, to define a calibration method that ensures that the AS and VS are similar to the reference protocol.

Image noise-based dose adaptation in dynamic volume CT of the heart: dose and image quality optimisation in comparison with BMI-based dose adaptation.

Objectives: To compare the image quality and radiation dose using image-noise (IN)-based determination of X-ray tube settings compared with a body mass index (BMI)-based protocol during CT coronary angiography (CTCA).

Methods: Two hundred consecutive patients referred for CTCA to our institution were divided into two groups: BMI-based, 100 patients had CTCA with the X-ray tube current adjusted to the patient's BMI while maintaining a fixed tube potential of 120 kV; IN-based, 100 patients underwent imaging with the X-ray tube current and voltage adjusted to the IN measured within the mid-left ventricle on a pre-acquisition trans-axial image. Two independent cardiac radiologists performed blinded image quality assessment with quantification of the IN and signal-to-noise ratio (SNR) from the mid-LV and qualitative assessment using a three-point score.

Determining the radiation dose reduction potential for coronary calcium scanning with computed tomography: an anthropomorphic phantom study comparing filtered backprojection and the adaptive iterative dose reduction algorithm for image reconstruction.

Purpose: This study describes a method to determine the lowest possible thresholds for volume computed tomographic dose index (CTDI(min)) and maximum tolerable pixel noise (SD(max)) values for coronary calcium scanning while maintaining accurate Agatston score values. The method was applied to a comparison between the iterative reconstruction (IR) and filtered backprojection (FBP) image reconstruction algorithms in a phantom study.

Materials And Methods: An anthropomorphic thoracic phantom with a calibration insert for the quantification of coronary calcium, containing 200, 400, and 800 mg HA/cm of calcium mass spheres of 1, 3, and 5 mm diameter (QRM GmbH, Moehrendorf, Germany), was scanned without (G1) and with (G2) an additional 2 cm-thick wrap of muscle-equivalent material.

Quantification of arterial plaque and lumen density with MDCT.

Purpose: This study aimed to derive a mathematical correction function in order to normalize the CT number measurements for small volume arterial plaque and small vessel mimicking objects, imaged with multidetector CT (MDCT).

Methods: A commercially available calcium plaque phantom (QRM GmbH, Moehrendorf, Germany) and a custom built cardiovascular phantom were scanned with 320 and 64 MDCT scanners. The calcium hydroxyapatite plaque phantom contained objects 0.