Format guide
Enhanced multi-frame DICOM (CT and MR) on iPhone and iPad
Enhanced DICOM stores a whole CT or MR series — sometimes several — in a single multi-frame file, with per-frame position and calibration data. Ossidex reads that per-frame information, applies the right rescale to each frame, splits multi-volume and 4D series into separate volumes, and opens them in 2D, MPR and 3D.
Classic vs Enhanced
| Classic | Enhanced multi-frame | |
|---|---|---|
| Files per series | One file per slice | One file for many frames |
| Geometry | In each file header | In per-frame functional groups |
| Typical sources | Most CT/MR, CBCT exports | Newer CT and MR scanners, some CBCT exports (e.g. single multi-frame files) |
What Ossidex handles
- Per-frame image position and orientation, so MPR and 3D are correctly shaped.
- Per-frame rescale for correct Hounsfield units in CT.
- Multiple stacks or time points in one file split into separate volumes, including classic 4D series.
- Large multi-frame files cached after the first build.
Dental CBCT
Some CBCT software exports a single multi-frame DICOM file — Planmeca Romexis recommends this option, for example. Ossidex opens both the single multi-frame file and the “set of single-frame files” variant. Romexis export options.
Enhanced vs classic: what changes for you
| Classic (single-frame) | Enhanced (multi-frame) | |
|---|---|---|
| Copying and sharing | Hundreds of files; easy to lose some | One file; nothing gets lost |
| Import speed | Many small reads | One large read, then cached |
| Metadata | Repeated in every file | Shared and per-frame groups |
| Support in older viewers | Universal | Sometimes missing — Ossidex reads both |
How to tell you have Enhanced DICOM
- The series is one large file (tens or hundreds of megabytes) instead of hundreds of small ones.
- The SOP Class is “Enhanced CT Image Storage”, “Enhanced MR Image Storage” or a similar multi-frame class.
- A DICOM tag viewer shows “Number of Frames” greater than one and per-frame functional groups.
You do not need to check any of this before importing — Ossidex detects it automatically.
Why calibration per frame matters
In Enhanced CT each frame can carry its own rescale slope and intercept. Applying one value to every frame would give wrong Hounsfield units on some slices — a problem for density readings and window presets. Ossidex applies the calibration of each frame individually, and caches the frame headers so large files reopen quickly.
Multi-stack and 4D files
Some Enhanced files hold several stacks (for example different reconstructions) or several time points of the same anatomy. Ossidex splits them into separate volumes so that MPR and 3D are built from one consistent stack; classic multi-file 4D series (for example diffusion acquisitions) are split the same way.
Import tips
- Import the file as it is — no conversion to classic DICOM is needed.
- If the file came inside a ZIP, import the ZIP; it is unpacked automatically.
- Very large files need free space for the cached volume; keep a few gigabytes free on the device.
Recent versions also handle the most common “it won’t open” cases from real discs: if you pick the disc’s Windows viewer (.exe) instead of the images, Ossidex suggests importing the whole folder; DICOM files without unique identifiers (UIDs) and JPEG images without a file extension are still imported; and helper files that come with the disc viewer no longer trigger a password prompt.
Frequently asked questions
Do I need to convert Enhanced DICOM first?
No. Import it as is.
My CBCT export is a single huge .dcm file — is that Enhanced DICOM?
Often, yes: several CBCT programs export the whole volume as one multi-frame file. Import it directly; it opens in 2D straight away and in MPR, 3D and the arch with Pro.
Why does the first opening take longer?
The volume is decoded and cached on the first open. Reopening the same study uses the cache and is much faster.
Does Enhanced DICOM work with MPR and 3D?
Yes. Once split into consistent volumes, Enhanced series open in MPR and 3D (Pro on your own studies).
Can I export Enhanced DICOM as images?
Yes — the current view or the series as JPEG images or PDF.
Sources
Related pages
What is a DICOM file? The medical imaging format explained
DICOM is the standard file format for medical images like CT, MRI and X-ray. What is inside a DICOM file, how studies and series work, and how to open one.
Planmeca Romexis
Open Romexis DICOM exports and patient discs made with Romexis Viewer.
MPR and 3D volume rendering on iPhone and iPad
Multi-planar reconstruction with linked crosshairs, oblique planes and slab MIP, plus 3D volume rendering with presets and clipping, for CT, CBCT and MRI.
How Ossidex reads and renders DICOM on iPhone and iPad
How Ossidex decodes DICOM, JPEG 2000 and HTJ2K, rebuilds volumes for MPR and 3D, and renders them with Metal on iPhone and iPad — all on the device.