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Measurement Tools

NavNX provides measurement tools for taking precise anatomical measurements on both 2D slices and the 3D bone model. Measurements are calibrated using the pixel spacing data embedded in the DICOM files.

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Bone 3D View

On the Bone 3D view, measurements are placed via the right-click context menu.

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Length (Distance)

1

Right-click on the bone surface

Right-click where you want to start the measurement. A context menu appears.
2

Select Measure distance

Click Measure distance from the menu. The first point is placed at the click location.
3

Left-click for the second point

A prompt appears: “Click on bone surface to place point 2/2”. Left-click on the bone surface to complete the measurement. The distance is displayed in millimetres.

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Angle

1

Right-click on the bone surface

Right-click where you want to start the measurement.
2

Select Measure angle

Click Measure angle from the context menu. The first point is placed.
3

Left-click for two more points

Click the vertex (centre point), then the third point. The angle is displayed at the vertex in degrees.

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Camera Interaction

When you orbit, zoom, or pan the 3D view, the on-screen measurement markers (lines and labels) are automatically hidden. This is intentional — screen-space markers become misleading when the perspective changes. Your measurement data is not lost. It remains visible in the properties panel sidebar and is saved with the case.

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Erasing Measurements

Right-click near a measurement and select Erase nearest to remove it. Alternatively, use the Clear all button in the measurement overlay or the × button next to each measurement in the sidebar.

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2D Slice Views (Stack / MPR)

On 2D slice views, measurements are placed using the toolbar tools.

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Length Tool

1

Activate the tool

Click the Length button in the toolbar (ruler icon) or press L.
2

Place the first point

Click on the viewport to set the start point.
3

Place the second point

Click again to set the end point. The measurement is displayed immediately in millimetres.

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Angle Tool

1

Activate the tool

Click the Angle button in the toolbar (protractor icon) or press A.
2

Place three points

Click to set the first point, then the vertex (centre), then the third point. The angle is displayed at the vertex.

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Annotations

Each measurement can be annotated with a label (e.g. “PCL entry to plateau”):
  • In the sidebar, type in the label field below each measurement
  • On the 3D overlay, click the ✎ icon next to a measurement

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Persistence

Measurements are saved as part of the case plan. They persist across:
  • Switching between view modes
  • Closing and reopening the case
  • Camera changes on the 3D view (data preserved, markers refresh)
Measurements are included in the pre-op report when you print or export it.