Comparison of Hounsfield Unit variability between two same model photon counting CT detector systems. A phantom study...

Area of Science:

• Medical Imaging
• Radiology
• Physics

Background:

• Accurate lung density quantification using Hounsfield Units (HU) is vital for monitoring diseases like emphysema via chest CT.
• Reproducibility of HU quantification on independent photon counting detector CT (PCD-CT) systems, especially for lung imaging, requires thorough evaluation.

Purpose of the Study:

• To assess the reproducibility of Hounsfield Unit (HU) quantification for lung density on two independent PCD-CT systems.
• To evaluate the impact of radiation exposure, iterative reconstruction, and reconstruction kernels on HU reproducibility in lung imaging.

Main Methods:

• A COPDGene phantom with air, water, and lung densities was scanned on two independent PCD-CT systems.
• Scans were performed using three radiation exposures (full, half, and one-eighth dose) and two reconstruction kernels (Br40, Qr36).
• The effect of iterative reconstruction (levels 0 vs. 3) was also examined.

Main Results:

• Radiation exposure levels (full, half, one-eighth dose) showed minimal influence (<6 HU) on HU accuracy with Br40 and Qr36 kernels.
• Iterative reconstruction levels also had a minimal impact (<6 HU) on HU accuracy with the tested kernels.
• Reproducible HU quantification was achieved across both PCD-CT systems, irrespective of changes in CTDIvol, iterative reconstruction level, and reconstruction kernel.

Conclusions:

• Photon counting detector CT systems provide reproducible Hounsfield Unit quantification for lung density.
• The evaluated PCD-CT systems demonstrate robustness in HU accuracy across different radiation doses, iterative reconstruction levels, and reconstruction kernels.
• These findings support the use of PCD-CT for consistent and reliable monitoring of lung diseases like emphysema.