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File-opening guide

How to open DICOM files without a .dcm extension

A medical image can be valid DICOM without a .dcm extension; import the complete folder in a DICOM viewer that checks file contents. Do not add extensions to every file, because the folder also contains indexes, viewer programs and other non-image data.

By the Ossidex team · How we write and check these pages · Updated

Download on the App StoreFree to download · iPhone & iPad · iOS 17+

Blank file icons are not a format test

What you haveWhat it means
Short names such as IM000001An illustrative DICOM media filename. The name alone does not identify the anatomy, slice order or even whether the file is DICOM.
DICOMDIRAn extensionless index, not an image. Preserve it together with the referenced folders.
Other extensionless filesMay be images or unrelated data. Ossidex inspects supported content; a missing suffix is not a universal support guarantee.

How to open the images

  1. Keep the original filenames. Copy the disc folder without renaming, sorting or flattening its contents. DICOMDIR references depend on the original paths.
  2. Import the folder on iPhone or iPad. In Ossidex, tap +, then Folder. Select the copied folder containing the images, not just the launcher or index. If you received a ZIP, choose Files / ZIP instead. These are the English app labels.
  3. Use the folder on Mac too. Choose Open folder in the browser viewer. Avoid a file-search filter that selects only names ending in .dcm.
  4. Check the imported examination. Open the study, select the intended series and scroll through its images. Compare the examination date and series with the clinic’s export. An image appearing on screen is not proof that every series arrived.

What to check if it still does not open

The DICOM media standard defines file identifiers independently of descriptive filenames. A viewer should read image metadata rather than infer slice order from names. An extensionless file is not necessarily DICOM: some clinic packages contain proprietary data.

If nothing imports, keep the originals and ask the clinic whether it supplied DICOM or its viewer’s own format. The filename is useful for describing the problem, but changing it cannot supply a missing decoder or reconstruct missing pixels.

Viewer options and format limits

On a Mac, open the browser viewer and choose Open folder for the complete DICOM folder or Open files for a ZIP. Browser format and memory limits differ from the iPhone/iPad app; a successful import does not establish that the examination is complete.

See the matching format or export guide and tested samples and compatibility limits. Ossidex is a viewer and planning aid, not a diagnostic device.

Frequently asked questions

Can I rename every file to .dcm?

It is unnecessary for supported DICOM files and can break index references. Import the original folder first.

Does the absence of .dcm mean the scan is corrupted?

No. DICOM media commonly uses extensionless names. File content and completeness determine whether it can be opened.

Sources

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