Use mean diameter
Enter the long and short axial diameters. The assistant calculates their arithmetic mean and displays it to one decimal place.
Lung cancer screening CT assistant
Lung-RADS v2022 Calculator
Determine the ACR Lung-RADS category for solid, part-solid, ground-glass, airway, juxtapleural, and atypical cyst findings—and review the corresponding screening-management pathway.
Automatic mean diameterScreening-only guardrailACR v2022 source linked
Educational clinical decision support. This assistant does not interpret CT images, assign a final radiology assessment, diagnose cancer, or create patient-specific orders. Use the most suspicious finding and verify every result against the official ACR document and local screening program.
ACR Lung-RADS v2022 pathway
Classify the most suspicious screening finding
Use CT descriptors from the radiology interpretation. For multiple findings, the overall examination category is driven by the most suspicious finding.
Step 1 · Applicability
Confirm the examination context
Step 2 · Finding type
Select the pathway that best matches the report
Step 3 · Size and behavior
Enter the axial measurements
Total nodule diameter
Calculated mean: 8.0 mm
Finding behavior
Lung-RADS growth generally requires an increase greater than 1.5 mm in mean diameter within 12 months.
Calculated locally in your browserNo patient data uploadedVersion and source always displayed
ACR v2022 at a glance
Lung-RADS categories and management
The finding-specific thresholds in the calculator determine the category. This compact table explains the category-level management context without replacing the complete official table and notes.
| Category | Meaning | General management |
|---|---|---|
| 0 | Incomplete | Comparison or additional imaging; selected infectious/inflammatory findings receive 1–3 month LDCT |
| 1 | Negative | Annual screening LDCT in 12 months |
| 2 | Benign appearance or behavior | Annual screening LDCT in 12 months |
| 3 | Probably benign | 6-month screening LDCT |
| 4A | Suspicious | 3-month screening LDCT; consider PET/CT when the solid portion is ≥8 mm |
| 4B | Very suspicious | Diagnostic evaluation, with CT, PET/CT, sampling, and/or referral chosen clinically |
| 4X | Additional suspicious features | Individualized diagnostic evaluation based on the feature that increases concern |
Measure the solid component
For part-solid nodules, enter both the total nodule and the solid component. The solid component often determines category 4A versus 4B.
Separate growth from slow growth
Growth generally means more than 1.5 mm within 12 months. Slower growth over multiple exams can still place a solid or part-solid nodule in category 4B.
Do not mix pathways
Lung-RADS versus Fleischner guidelines
Screening LDCT
Use Lung-RADS to standardize screening CT assessment and management. Begin upstream with the pack-year and LDCT eligibility calculator.
Incidental nodule
Use the Fleischner nodule assistant when the incidental finding meets its age and clinical eligibility criteria.
For probability estimation within an appropriate broader pathway, the Brock calculator answers a different question: estimated malignancy probability rather than a screening category.
Frequently asked questions
Lung-RADS categories and lung nodule screening
What is a Lung-RADS score?
Lung-RADS is a standardized ACR category for findings on lung cancer screening CT. Categories reflect the most suspicious finding and connect it to a management recommendation; the category is not a percentage probability of cancer.
Is Lung-RADS v2022 still current in 2026?
The ACR Lung-RADS resource page lists v2022 as the current release as of this page’s August 2026 review. PulmTools states the version explicitly so a future update can be identified rather than silently mixing criteria.
What is the difference between Lung-RADS and Fleischner?
Lung-RADS applies to lung cancer screening CT. Fleischner recommendations address eligible incidentally detected nodules and exclude screening examinations. The two frameworks should not be interchanged.
What does Lung-RADS 3 mean?
Category 3 means probably benign under the screening framework and generally leads to a 6-month LDCT. The exact reason depends on morphology, size, whether the finding is new, and stepped follow-up rules.
What does Lung-RADS 4A mean?
Category 4A is suspicious and generally leads to a 3-month LDCT. PET/CT may be considered when the solid nodule or solid component is at least 8 mm.
What does Lung-RADS 4B mean?
Category 4B is very suspicious. Diagnostic chest CT, specialist evaluation, PET/CT when technically appropriate, and/or tissue sampling are considered according to the finding, malignancy probability, comorbidity, and patient preference.
What is Lung-RADS 4X?
Category 4X applies when a category 3 or 4 finding has additional features that increase suspicion for lung cancer. It requires judgment because the additional feature—not size alone—drives escalation.
How does Lung-RADS define growth?
The v2022 document generally defines growth as an increase greater than 1.5 mm in mean diameter within 12 months. Slow growth across multiple screening examinations can still make a solid or part-solid nodule very suspicious.
Evidence base
Primary guideline and reference material
Sources and current-release status reviewed August 16, 2026. The category system is identified as Lung-RADS v2022 because that remains the current ACR release; “2026” describes this review date, not a newly issued guideline version.
American College of Radiology — Lung-RADS v2022 Assessment CategoriesPrimary category thresholds, descriptors, management recommendations, and explanatory notes used by this assistant.American College of Radiology — Lung-RADS resource hubOfficial current-release page, educational resources, and lung cancer screening materials.American College of Radiology — Lung-RADS v2022 Summary of ChangesOfficial explanation of updates covering atypical pulmonary cysts, juxtapleural nodules, inflammatory findings, airway nodules, growth, and stepped management.Christensen et al. ACR Lung-RADS v2022: Assessment Categories and Management Recommendations (Radiology, 2024)Peer-reviewed overview of the v2022 update and its evidence-informed revisions.ACR Appropriateness Criteria — Radiologic Management of Pulmonary Nodules and Masses (revised 2025)Contemporary ACR imaging context for pulmonary nodules outside a simple screening category calculation.
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