CT Low-Dose Lung Cancer Screening (Lung-RADS)

Indications

• Lung cancer screening in eligible adults: typically age 50-80 (USPSTF 2021), ≥20 pack-year smoking history, current smoker or quit within 15 years, asymptomatic
• Annual screening per Lung-RADS recommendations
• Must meet shared decision-making / smoking cessation counseling and program eligibility (CMS/USPSTF)

Patient prep

• No contrast and no NPO
• Confirm screening eligibility and that exam is asymptomatic screening (not diagnostic)
• Arms above head; coach single end-inspiratory breath-hold
• Register exam in a recognized screening registry (e.g. ACR Lung Cancer Screening Registry)

Contrast

Technique

• Supine, arms up; single end-inspiratory breath-hold covering lung apices through costophrenic angles
• LOW-DOSE technique: 120 kV (100 kV in small patients) with reduced tube current; target CTDIvol ≤3 mGy (standard-size patient) / effective dose ~1-1.5 mSv
• Tube current ~40-60 mAs or AEC tuned for low dose; iterative reconstruction mandatory to preserve nodule detection
• Reconstruct thin (≤1-1.25 mm) sharp/lung kernel and soft-tissue kernel; coronal reformats; MIP improves nodule detection
• Min 16-detector (NLST used ≥4-detector) scanner to scan in one breath-hold

Series / Sequences

Key points

• Report with Lung-RADS v2022: category 1-2 = annual screening; 3 = 6-month LDCT; 4A = 3-month LDCT or PET/CT; 4B/4X = chest CT +/- PET/biopsy; category S for clinically significant incidental findings
• Use volumetric nodule measurement and compare with priors; growth defined by Lung-RADS thresholds
• Keep dose low (CTDIvol ≤3 mGy standard patient) per ACR designated lung screening center requirements
• Non-contrast only; CMS requires registry participation and shared decision-making documentation

References