Image Quality Assessment in Torso Phantom Comparing Effects of Varying Automatic Current Modulation with Filtered...

Area of Science:

• Radiology
• Medical Imaging
• Image Reconstruction

Background:

• Computed tomographic (CT) imaging relies on reconstruction algorithms to produce diagnostic images.
• Optimizing image quality while minimizing radiation dose is a key challenge in CT.
• Automatic tube current modulation (ATCM) adjusts radiation output based on patient anatomy.

Purpose of the Study:

• To compare the image quality of CT scans reconstructed using filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and a novel model-based iterative reconstruction (MBIR) technique.
• To evaluate these techniques across various noise levels generated by ATCM.
• To assess the impact of reconstruction methods on radiation dose.

Main Methods:

• A torso phantom was scanned using ATCM at 17 different noise levels.
• Images were reconstructed using FBP, ASIR, and MBIR algorithms.
• Objective and subjective image quality assessments were performed, along with effective dose calculations.

Main Results:

• MBIR demonstrated significant noise reduction and superior contrast-to-noise ratio (CNR) compared to ASIR and FBP.
• Subjective image quality ratings were highest for MBIR, followed by ASIR, then FBP.
• Effective doses ranged from 0.7 to 3 mSv, with meaningful image quality achieved at high noise indices with MBIR.

Conclusions:

• MBIR offers superior noise reduction and improved objective and subjective image quality over ASIR and FBP.
• Diagnostic image quality can be maintained with significant radiation dose reduction using MBIR, even at higher noise index settings.
• MBIR represents an advancement in CT image reconstruction for dose optimization.