How to open a .dcm file without installing hospital software
You can open a .dcm file without the hospital’s program by using any general DICOM viewer. Free viewers exist for Windows, Mac and Linux, in the browser and on Android. A normal photo app will not open the file, but a DICOM viewer does not need to come from the hospital.
Why the hospital program is not required
DICOM is an open standard, so the format is not tied to one program. The viewer that comes on a patient CD is a convenience, and it often only runs on Windows. The images inside the files can be read by any software that supports the standard.
If your file has no .dcm ending, that is common and not a sign of a problem. See what is a DICOM file.
On a computer
- Installed viewers. Several free desktop DICOM viewers are available for Windows, Mac and Linux. They are the best choice when you have a large scan and want a big screen. The downside is the install, and some are built for professionals and look complicated.
- The viewer on the disc. If you have the CD and a Windows computer, the bundled program usually starts without installing. It is limited to what the hospital chose to include.
In a browser
Some websites let you drag in a file and look at it. This is quick on a computer where you cannot install anything. Check how a given site works before using it. Some process files inside your browser and others upload them to a server. A DICOM file contains the patient’s name and other details, so uploading it is worth a second thought. See DICOM viewers and privacy.
On an Android phone
A phone is often the fastest option when someone sends you a file or you want to show a scan to a relative or a doctor. You install a DICOM viewer, then open a single file from your downloads, or open a whole folder if you copied a patient CD. A phone cannot read a disc itself, so the folder has to be copied over first. See how to open a DICOM CD on your phone.
Radix DICOM works this way on Android. It opens single .dcm files and whole folders, shows CT, MRI and X-ray, runs offline, needs no account, shows no ads and does not upload images.
What to look for in any viewer
| Question | Why it matters |
|---|---|
| Does it work offline? | Your images stay on your device |
| Does it need an account? | An account means more data is kept about you |
| Does it open folders? | A scan is often hundreds of files |
| Does it support compressed images? | Files can use JPEG, JPEG 2000 or RLE |
| Does it play multi-frame files? | Some studies are short loops |
Basic controls you will use
Once a file is open, a few controls do most of the work:
- Scroll through the slices of a series.
- Zoom and pan to look closer.
- Brightness and contrast. Medical images store a wide range of grey values, and a viewer shows part of that range at a time. See window and level explained.
If the file will not open
The file may be incomplete after an interrupted download, may use a format a particular viewer lacks, or may not be a DICOM file at all. Try a second viewer before assuming it is broken. See why a DICOM file will not open.
A note on use
Viewing your own images yourself is fine, but a free viewer is not a medical device and not a diagnostic tool. Any decision about your care belongs to your doctor, who works from the official report and the hospital’s own systems.