JawAtlasFeature
How JawAtlas is validated
A viewer is only useful to a researcher if the geometry is right and the file handling is honest. This page lists what is checked, how, and what is deliberately not claimed.
Geometry
Slices are ordered by projecting each file's ImagePositionPatient onto the slice normal, never by file name or instance number. Slice spacing is resolved from the positions, then sanity-clamped, and gaps or duplicate slices are reported before anything is built. Orientation labels (R, L, A, P, H, F) are derived from the ImageOrientationPatient cosines, so they remain correct on volumes that were acquired rotated or that you cut obliquely.
The transform between voxel indices and patient space was verified against the 3D Slicer region-of-interest markup that ships with the demo dataset: the markup is stored in LPS millimetres, and the app's transform reproduces its centre inside the expected voxel. Measurements are computed from the same transform, which is why the length and angle tools are described as calibrated.
DICOM and codecs
Supported transfer syntaxes are Implicit and Explicit VR Little Endian, Deflated, RLE Lossless and JPEG Lossless (processes 14 and 70). Each codec has its own tests, and the JPEG Lossless path is exercised by a hand-written encoder in the test suite that produces fixtures with known pixel values. Multi-frame files, MONOCHROME1 inversion, both pixel representations, and missing rescale tags are handled. A real reference dataset with a mixed study (a scout, a screenshot series and the acquisition) is used to prove that only the geometrically valid series is offered for import.
Hostile input
The DICOM parser is run against a corpus of mutated files (truncated headers, impossible lengths, nested undefined-length sequences, corrupted pixel data) and must fail cleanly on every one. The ZIP reader used for AirDrop archives is hardened against path traversal, absolute paths and decompression bombs. None of this makes the app immune to every malformed file, but it does mean a bad file produces an error message rather than a crash or a silently wrong volume.
Privacy by test
The importer reads a whitelist of technical tags. Tests feed in files with a patient name, ID, birth date and institution and then search the app's storage format for any of those strings; the build fails if one survives. A separate audit script fails the build if any networking symbol appears in the source. How the privacy design works.
The numbers
| Automated tests | 157 (XCTest), run serially on an iPhone simulator before every release |
|---|---|
| Demo volume | 480 x 480 x 320 voxels, 0.266 x 0.266 x 0.252 mm, Explicit VR Little Endian |
| Reference dataset | A second public case, 204 x 204 x 201 voxels at 0.3 mm isotropic, used as a multi-series parser fixture |
| Third-party dependencies | None; the DICOM parser, codecs and ZIP reader are written from scratch in Swift |
| Networking code | None, enforced by an audit script |
What is not claimed
JawAtlas has no regulatory clearance and seeks none; it is an education and training aid. Grey values are shown as grey values, never as Hounsfield units, and there are no density readouts, ROI statistics, segmentation or registration. For those tasks the viewer comparison points to the right desktop tools. Researchers who need a citable record of the method can quote this page and the demo dataset DOI.
Questions students ask
Is JawAtlas validated as a medical device?
No. It is an education and training aid and makes no clinical claims. The checks described here are engineering validation of geometry and file handling, not a regulatory clearance.
Can I rely on the millimetre measurements for research?
They are computed from the pixel spacing and slice spacing in the DICOM headers, with the volume transform checked against a 3D Slicer markup. For a study you should still verify on your own dataset, for example by measuring a known phantom distance.
What happens to a file the parser cannot read?
It is counted and reported, and the import continues with the rest. Lossy JPEG, JPEG 2000 and JPEG-LS files are rejected per file with a clear message rather than failing the whole series.
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 2026-10-14