Lung cancer screening: minimum tube current required for helical CT

Area of Science:

• Radiology
• Medical Imaging
• Pulmonary Medicine

Background:

• Lung cancer screening with computed tomography (CT) is crucial for early detection.
• Helical CT protocols aim to balance image quality with radiation dose.
• Optimizing tube current is essential for effective and safe lung cancer screening.

Purpose of the Study:

• To determine the lowest effective tube current for helical CT in lung cancer screening.
• To assess the impact of reduced tube current on image quality and nodule detectability.
• To investigate location-specific variations in optimal tube current.

Main Methods:

• Seven healthy volunteers underwent helical CT scans of the lung at varying tube currents (6-50 mAs).
• Computer-generated nodules (6 mm, ground-glass opacity) were superimposed on images.
• Subjective image quality and nodule detectability were assessed by six observers.
• Standard deviations of CT numbers were calculated and analyzed by lung zone.

Main Results:

• Image quality at 20 mAs was comparable to 50 mAs.
• Nodule detectability remained high with reduced tube current: 20 mAs (upper lung), 12 mAs (middle lung), and 18 mAs (lower lung).
• Lung apex and base showed increased standard deviations in CT numbers as dose decreased.

Conclusions:

• Optimal tube current for helical CT lung cancer screening is location-dependent.
• Future CT protocols should allow for dynamic adjustment of tube current during scanning.
• Tailoring tube current to lung region can improve screening efficiency and safety.