GammaMetric — Scan Detectability Intelligence Demo

LIDC-IDRI-0003

✓ TIER 1 — Normal

Acquisition Standard acquisition

78.2%

3–6mm nodules

reference

vs baseline

78.2%

Overall sensitivity

Report addendum

"Detection sensitivity for pulmonary nodules ≥3mm is within established benchmarks for this study."

LIDC-IDRI-0007

✓ TIER 1 — Normal

Acquisition Reduced dose — mild noise elevation

71.8%

3–6mm nodules

−4.1pp

vs baseline

74.1%

Overall sensitivity

Report addendum

"Detection sensitivity for pulmonary nodules ≥3mm is within established benchmarks for this study."

LIDC-IDRI-0011

✕ TIER 3 — Cannot Reliably Exclude

This study cannot reliably exclude small pulmonary nodules.

Acquisition Reconstruction interval: 5mm

44.6%

3–6mm nodules

−18.9pp

vs baseline

59.3%

Overall sensitivity

78.2%

Baseline (3–6mm)

→

44.6%

This scan (3–6mm)

Report addendum

"Detection of pulmonary nodules <6mm is limited under current acquisition parameters. Small nodules cannot be reliably excluded."

LIDC-IDRI-0016

⚠ TIER 2 — Reduced Sensitivity

Sensitivity for small nodules is meaningfully reduced under current acquisition parameters.

Acquisition Soft kernel — reduced edge resolution

68.9%

3–6mm nodules

−5.6pp

vs baseline

72.6%

Overall sensitivity

78.2%

Baseline (3–6mm)

→

68.9%

This scan (3–6mm)

Report addendum

"Given acquisition parameters, detection sensitivity for pulmonary nodules in the 3–6mm range is reduced. Small nodules may not be reliably excluded."

LIDC-IDRI-0042

⚠ TIER 2 — Reduced Sensitivity

Sensitivity for small nodules is meaningfully reduced under current acquisition parameters.

Acquisition Reduced dose — moderate noise elevation

67.3%

3–6mm nodules

−7.4pp

vs baseline

70.8%

Overall sensitivity

78.2%

Baseline (3–6mm)

→

67.3%

This scan (3–6mm)

Report addendum

"Given acquisition parameters, detection sensitivity for pulmonary nodules in the 3–6mm range is reduced. Small nodules may not be reliably excluded."

The Reconstruction Interval Problem

Sensitivity depends not just on reconstruction interval size — but on where the nodule falls within that interval. A nodule straddling two slices is harder to detect than one centered on a slice, even when the AI reports identical confidence.

3–6mm Nodule Sensitivity

1mm Baseline

84.8%

3mm Interval

82.4%

5mm Interval

71.6%

154-case LIDC-IDRI perturbation study · arXiv:2603.26785

Reconstruction interval z-phase sensitivity analysis

Left: overall sensitivity by reconstruction interval. Right: sensitivity as a function of nodule z-phase — where the nodule falls within the reconstruction cycle. Phase 0 = nodule centered on a slice; phase 0.5 = nodule straddling two slices (worst case). AI confidence score does not change. Detectability does.