JawAtlasFeature
Measure in millimetres, read angles in degrees
Two taps give a length, three give an angle, each calibrated from the scan's own voxel spacing. Nothing else, on purpose.
How measuring works
In the MPR stage, choose Measure. The toolbar asks you to tap where the measurement should start, then where it ends, and the length appears in millimetres on the slice. Angle works the same way with three taps: the first arm, the vertex, the second arm. A trash button removes a measurement. Step by step.
What calibrated means
A CBCT voxel has a physical size, stored in the DICOM headers as pixel spacing and slice thickness or spacing. The demo scan, for example, has 0.266 mm voxels in the plane and 0.252 mm between slices. JawAtlas multiplies pixel distances by those values, so a measurement is exact for the points you tapped. The scale ruler in the corner of each pane (20 mm at a typical zoom, adapting as you zoom) is drawn from the same numbers. More on voxel size and field of view.
The part that is up to you
The number is only as good as the slice. Measure a root on a slice that misses its long axis and you measure a chord, not the length. The habit the app tries to teach is to move the crosshair until the structure is at its widest in the plane you are using, confirm in a second plane, and only then tap. This is why Measure sits next to Move rather than in a separate screen.
What it will not do
No ROI statistics, no density readouts, no nerve-distance safety values, no implant libraries. Those belong to clinical software with a regulatory status JawAtlas does not have and does not want. It is an education and training aid. Why CBCT grey values are not Hounsfield units.
Questions students ask
How accurate are the measurements?
They are computed from the pixel spacing and slice spacing stored in the DICOM headers, so the arithmetic is exact to the voxel. The real uncertainty is where you tapped and whether the slice passes through the widest part of the structure. Treat every number as a learning exercise, not a clinical value.
Can I measure on the panoramic view?
Measurements work in the three MPR panes, where each pixel has a known size. A reconstructed panoramic stretches and averages the volume along a curve, which is why it is the wrong place to measure.
Does JawAtlas measure bone density?
No. CBCT grey values are not calibrated Hounsfield units, so the app deliberately offers no density readout and no ROI statistics.
JawAtlas is an education and training aid. It is not a medical device and must not be used for diagnosis, treatment planning or any clinical decision.
Last reviewed 2026-10-13