Obese patient imaging: Potential dose reduction with photon-counting CT

Area of Science:

• Medical Imaging
• Radiological Physics
• Diagnostic Radiology

Background:

• Photon-counting CT (PCCT) offers advantages over energy-integrating detector CT (EID-CT), particularly for low-dose scans and imaging larger patients.
• Minimizing image noise is crucial for diagnostic accuracy, especially with rising obesity rates.

Purpose of the Study:

• To evaluate the dose efficiency of cadmium-zinc-telluride (CZT) based PCCT compared to EID-CT across various phantom sizes.
• Assess the impact of phantom size on noise reduction and dose efficiency.

Main Methods:

• Scanned patient-specific 3D-printed pancreas and tissue-mimicking phantoms in extension rings simulating 50th-95th percentile waist circumferences.
• Acquired data on PCCT and EID-CT systems with CTDIvol ranging from 0.5 to 19.4 mGy.
• Quantified noise and non-Poisson noise to evaluate dose efficiency and potential dose reduction at matched noise levels.

Main Results:

• PCCT demonstrated superior noise reduction compared to EID-CT across all phantom sizes, with average reductions of 22% to 28%.
• Noise reduction was more pronounced at lower doses and larger phantom sizes, with significant decrease in non-Poisson noise for PCCT (p < 0.013).
• PCCT enabled potential dose reductions of 33% (50th percentile) and 44% (95th percentile) at matched noise levels.

Conclusions:

• PCCT exhibits superior dose efficiency compared to EID-CT across diverse phantom sizes.
• The enhanced dose efficiency of PCCT facilitates both noise reduction and potential dose reduction, benefiting obese patient imaging and low-dose applications.
• Further research using task-based image quality metrics is needed before clinical dose reduction implementation.