Image quality in CT thorax: effect of altering reconstruction algorithm and tube load

Area of Science:

• Medical Imaging
• Radiology
• Image Reconstruction

Background:

• Iterative reconstruction (IR) algorithms, particularly model-based ones like advanced modelled iterative reconstruction (ADMIRE), possess non-linear properties that can influence computed tomography (CT) image texture.
• Assessing the impact of these algorithms and radiation dose on image quality is crucial for optimizing diagnostic performance and patient safety.

Purpose of the Study:

• To evaluate the effect of ADMIRE algorithm strengths and radiation dose on the image quality of CT thorax scans.
• To compare the image quality achieved with ADMIRE against traditional filtered back projection (FBP).

Main Methods:

• Dual-source CT data were acquired from 20 patients at reference tube loads of 20, 45, and 65 milliampere-seconds (mAs).
• Images were reconstructed using filtered back projection (FBP) and ADMIRE at strengths 3, 4, and 5.
• Six radiologists independently assessed image quality using predefined criteria, and results were analyzed with ordinal logistic regression.

Main Results:

• Both reduced tube load (20 mAs) and all ADMIRE strengths significantly impacted image quality compared to 65 mAs and FBP (p < 0.001).
• Increasing tube load from 45 to 65 mAs resulted in improved image quality for three out of six assessed criteria.
• ADMIRE demonstrated a significant improvement in perceived image quality across all criteria compared to FBP.

Conclusions:

• Replacing FBP with ADMIRE in CT thorax imaging leads to significant improvements in perceived image quality.
• The use of ADMIRE holds the potential to reduce radiation dose by approximately 70% without a discernible loss in image quality.