Iterative Reconstruction in Dose Reduction of A Head CT Examination and Corresponding Acquisition Parameter Selection

Area of Science:

• Radiology
• Medical Imaging
• Radiation Oncology

Background:

• Computed tomography (CT) is essential for head imaging, but radiation exposure is a concern.
• Iterative reconstruction (IR) techniques offer potential for dose reduction in CT.
• Optimizing IR parameters is crucial for balancing dose and image quality.

Purpose of the Study:

• To investigate radiation dose reduction in head CT using iterative reconstruction.
• To evaluate the relationship between milliampere second (mAs), kilovoltage (kV), and IR strength.
• To assess these factors in a live ovine (sheep) model.

Main Methods:

• Sheep were scanned using a SOMATOM Force CT scanner.
• Images were reconstructed with filtered back projection (FBP) and Advanced Modeled Iterative Reconstruction (ADMIRE) at strengths 1-5.
• Neuroradiologists evaluated image quality (low-contrast detectability and texture) across 216 dose/kV/reconstruction combinations.

Main Results:

• Maximum dose reduction of 75% was achieved with ADMIRE-3 at 100 kV (gray-white matter differentiation) and ADMIRE-5 at 120/140 kV (image texture).
• Combining both metrics yielded a maximum dose reduction of 50% at 120 kV with ADMIRE-3.
• Higher kV levels and stronger IR settings did not consistently improve results.

Conclusions:

• Iterative reconstruction, particularly ADMIRE, can significantly reduce radiation dose in head CT while maintaining diagnostic image quality.
• A 50% dose reduction is achievable at 120 kV with ADMIRE-3, demonstrating the effectiveness of optimized IR parameters.
• Further understanding of dose-voltage-reconstruction relationships in IR could enable even greater dose reductions in clinical practice.