Nodule volume doubling time calculator
Enter the nodule diameter on each study and the interval between scans. Volume scales with the cube of diameter, so modest diameter change means large volume change — the calculator makes that explicit and maps the result to the standard interpretation bands.
Formula. Volume scales with diameter cubed, so
VDT = t · ln 2 / (3 · ln(d₂/d₁)). A 6 mm → 8 mm change
is a 2.4× volume increase — diameter understates growth.
Interpretation bands
| Doubling time | Typical meaning |
|---|---|
| VDT < 100 days | Rapid growth — typical of aggressive malignancy (also seen with infection/inflammation; correlate clinically). |
| VDT 100-400 days | The classic growth range of solid non-small-cell lung cancer — suspicious; tissue diagnosis or PET/CT is usually warranted. |
| VDT > 400 days | Indolent growth — favours benignity or very indolent malignancy; note that subsolid adenocarcinoma-spectrum lesions can double over 3-5 years, so long-interval follow-up is still prudent for GGNs. |
Caveats
- Subsolid nodules: adenocarcinoma-spectrum ground-glass lesions can have VDTs of 3–5 years — a long VDT does not clear a persistent GGN.
- Measurement error: at small sizes, 1 mm of caliper variability can swing the VDT wildly; volumetry is more reproducible than diameter.
- Stability benchmark: 2-year stability is the conventional benignity criterion for solid nodules.
Related
- Fleischner follow-up calculator — incidental nodules
- Lung-RADS calculator — screening CT
- Lung-RADS or Fleischner? Picking the right pathway
- All radiology calculators
Source. Standard exponential growth model; interpretation per the NELSON trial growth analyses (Horeweg N, et al. Lancet Oncol 2014;15(12):1332-1341). View on PubMed
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