Lung-RADS (Lung CT Screening Reporting and Data System) is a quality assurance tool published by the American College of Radiology (ACR) to standardize lung CT screening reporting and management recommendations. Version 2022 is the current edition.

Does this tool replace a radiologist?

No. This is a reference and educational tool only. All clinical decisions — including final Lung-RADS category assignment and patient management — must be made by a qualified radiologist reviewing the actual images.

What does the "S" modifier mean?

The "S" modifier is added to any Lung-RADS category when a clinically significant or potentially significant finding (other than a lung nodule) is identified on the CT, such as a pleural effusion or mediastinal adenopathy. This tool notes when S may apply but does not auto-assign it.

What is the 4X category?

Category 4X is assigned when a nodule has one or more additional suspicious features — such as spiculation, lymphadenopathy, or significant growth — that increase suspicion beyond what size alone would indicate. It carries a >15% estimated malignancy risk and typically warrants PET-CT or tissue sampling.

How are part-solid nodules classified?

For part-solid nodules, Lung-RADS uses the solid component diameter for risk stratification once a solid component is ≥6 mm. If the solid component is <6 mm, the overall nodule diameter drives category assignment.

What size thresholds does Lung-RADS 2022 use for solid nodules?

Solid nodules: <6 mm = category 2; 6 to <8 mm = category 3; ≥8 mm = category 4A; and modifiers push to 4B (≥15 mm or nodule with suspicious features) or 4X.

Lung-RADS Score Helper

Enter CT nodule findings to get the ACR Lung-RADS 2022 category and recommended follow-up interval.

Nodule Findings

Nodule morphology

Solid Part-solid (mixed GGO + solid) Ground-glass only (non-solid)

Mean nodule diameter (mm)

Additional suspicious features

Spiculation or lobulation Solid nodule growth (>1.5 mm mean diameter within 12 months) New or growing solid component (enter its size above) Suspicious mediastinal / hilar lymphadenopathy

Enter nodule findings on the left and click Calculate

Summary

Lung-RADS (Lung Imaging Reporting and Data System) is the ACR standard for classifying pulmonary nodules found on low-dose CT lung screening. This tool walks you through nodule type, size, and suspicious features to assign the correct category (2 through 4X) and return the ACR 2022 recommended follow-up interval. For educational and reference use; clinical decisions must be made by a qualified radiologist.

How it works

Select whether the nodule is solid, part-solid, or ground-glass (pure non-solid).
Enter the nodule's average diameter in millimeters.
For part-solid nodules, enter the solid component diameter separately.
Check any suspicious features (spiculation, location, growth) that apply.
The tool applies ACR Lung-RADS 2022 decision logic and returns the category and follow-up recommendation.

Use cases

Radiologists double-checking Lung-RADS category assignment at the reading workstation.
Pulmonologists reviewing lung screening reports with patients.
Medical students and residents learning Lung-RADS 2022 decision trees.
Clinicians coordinating follow-up for nodules found on lung cancer screening CT.
Quality assurance review of lung screening program reports.
Nursing staff preparing patient education materials on lung nodule monitoring.

Frequently Asked Questions

Last updated: 2026-06-18 · Reviewed by Nham Vu

Lung-RADS Score Helper

Nodule Findings

ACR 2022 Follow-up Recommendation

Classification rationale

Summary

How it works

Use cases

Frequently Asked Questions

Lung-RADS Score Helper

Use the Lung-RADS Score Helper

Nodule Findings

ACR 2022 Follow-up Recommendation

Classification rationale

Summary

How it works

Use cases

Frequently Asked Questions