Low-dose lung cancer screening with photon-counting CT: a feasibility study

Area of Science:

• Radiology
• Medical Imaging
• Photon-Counting CT

Background:

• Low-dose computed tomography (CT) is crucial for lung cancer screening.
• Conventional energy-integrating detector (EID) CT systems face limitations in image quality at reduced radiation doses.
• Photon-counting detector (PCD) CT technology offers potential advantages for dose reduction and image quality enhancement.

Purpose of the Study:

• To evaluate the feasibility of using whole-body PCD CT for low-dose lung cancer screening.
• To compare the performance of PCD CT against conventional EID CT.
• To assess image quality metrics including Hounsfield unit (HU) accuracy, noise, and contrast-to-noise ratio (CNR) at various radiation doses and tube voltages.

Main Methods:

• Radiation dose-matched scans of the COPDGene 2 phantom were acquired using both EID and PCD CT systems.
• Scans were performed at different radiation dose levels (CTDIvol: 3.0, 1.5, and 0.75 mGy) and tube voltages (120, 100, and 80 kVp).
• Quantitative analysis included HU accuracy, noise levels, and CNR for detecting ground-glass nodules (GGN) and emphysema.

Main Results:

• PCD CT demonstrated superior HU accuracy and stability across all tested parameters compared to EID CT.
• PCD CT exhibited significantly lower noise levels, especially at lower radiation doses (0.75 mGy) and tube voltages (100 and 80 kVp).
• PCD CT resulted in higher CNR for GGN and emphysema detection, with up to 10% less noise and 11% higher CNR at 0.75 mGy.

Conclusions:

• PCD CT provides better HU stability and reproducibility for lung, GGN, and emphysema regions at lower radiation doses than EID CT.
• PCD technology shows promise for reducing radiation exposure in lung cancer screening without compromising diagnostic image quality.
• The findings support the clinical feasibility of PCD CT for effective low-dose lung cancer screening.