Patient guide
How to open a CT or MRI scan CD on a Windows PC or Mac
You've been handed a disc with your scan on it. Here is how to look at it, step by step, on any computer.
Last updated: October 2026
The short answer
A CT or MRI scan CD holds your images as DICOM files, plus an index file called DICOMDIR, and many discs include a viewer program. On Windows, open the disc in File Explorer and run the viewer on it, or install a free DICOM viewer such as Weasis or MicroDicom (free for non-commercial use). On a Mac, use a USB CD drive or a copy on a pen drive, and a Mac viewer such as Horos or Weasis, because the viewer on the disc is usually Windows-only.
The viewer shows images, not a diagnosis. The radiologist's report is what explains them. Your scan is personal health data, so only use trusted software.
What's on a scan CD?
Your scan is stored as many small image files in a medical format called DICOM. A CT or MRI is not one picture. It is a stack of thin slices, often hundreds of them, and each slice is its own file.
DICOM images
Usually in a folder named DICOM or IMAGES. File names are often just numbers, with or without .dcm at the end.
DICOMDIR
An index of everything on the disc. Viewers read it to show your study in the right order.
Often, a viewer
Many discs include a small viewer program. It is almost always for Windows.
Want the full picture? Read what a DICOM file is.
Copy the disc first
Discs scratch and wear out. Before anything else, copy everything on the disc, every folder and file including DICOMDIR, into one folder on your computer or a pen drive. Keep the folders exactly as they are. A partial copy may not open. Keep the original disc somewhere safe.
How do I open a scan CD on Windows?
Open the disc in File Explorer and run the viewer on it. If there isn't one, install a free DICOM viewer.
- 1
Put the disc in and wait a moment
Windows often does not start the disc by itself any more. If nothing happens, or Windows asks what to do, that is normal. Go to the next step.
- 2
Open the disc in File Explorer
Press the Windows key + E to open File Explorer. Click "This PC" on the left, then double-click the CD or DVD drive. You will see the files on the disc.
- 3
Look for the viewer that came with the disc
Many discs include a viewer program. Look for a file ending in .exe, often with a name like "viewer", "start" or "autorun", or a file called README. Double-click it. If Windows asks whether to allow it, only say yes if the disc came straight from your hospital or scan center.
- 4
No viewer, or it won't start? Use a free one
Install a DICOM viewer on your computer, then open the disc from inside it. Weasis is free and open source. MicroDicom is free for non-commercial use. Both are listed below, with what their makers say.
- 5
Open the study and scroll through it
Inside the viewer, choose open (or open folder / open DICOMDIR) and pick the CD drive. Your scan appears as one or more series. Click a series, then scroll with the mouse wheel to move through the slices.
How do I open an MRI or CT CD on a Mac?
Get the files onto the Mac, then open them in a Mac DICOM viewer. The viewer on the disc won't run.
- 1
Connect a CD or DVD drive
Most current Macs have no CD drive. A USB CD/DVD drive works. Or ask someone with a drive to copy the whole disc onto a USB pen drive for you (see "Copy the disc first" below).
- 2
Skip the viewer on the disc
The viewer on most scan CDs is a Windows program (a file ending in .exe). It will not run on a Mac. That's fine: the images themselves open on a Mac.
- 3
Install a Mac DICOM viewer
Horos is free and open source, made for macOS. Weasis is free and open source and has a macOS version. OsiriX Lite is the free demo version of OsiriX. Download only from the maker's own website.
- 4
Import the disc or folder
In the viewer, choose import (or open) and select the CD, or the folder you copied. Horos and OsiriX copy the images into their own database first. Then double-click the study to open it.
- 5
Scroll through the slices
Click a series and scroll with the trackpad or mouse to move through it. That is all you need to look at your scan.
Which DICOM viewer should I use?
For simply looking at your own scan, a free viewer is plenty. These are well-known options. Download only from the maker's own website.
| Viewer | Runs on | Cost | What the maker says |
|---|---|---|---|
| Weasis ↗ | Windows, Mac, Linux | Free and open source | Per weasis.org, "free, and open" under EPL 2.0 / Apache 2.0, with install guides for Windows, macOS and Linux. |
| MicroDicom ↗ | Windows | Free for non-commercial use | Per microdicom.com, free for non-commercial use; a paid license is needed for business use. Runs on Windows 7–11. |
| Horos ↗ | Mac | Free and open source | Per the Horos project on GitHub, "a free, open source medical image viewer" for macOS, licensed under LGPL-3.0. |
| OsiriX Lite ↗ | Mac | Free demo version | Per osirix-viewer.com, the free demo version of OsiriX MD; the Lite version is not certified for primary diagnosis. |
| RadiAnt ↗ | Windows | Paid, with a free trial | Per radiantviewer.com, a paid Windows viewer with a free trial version; it is not a free product. |
Details are from each maker's website as of 26 October 2026. Licenses change, so check before you install. For a fuller comparison, see our guide to the best DICOM viewers.
What if I don't have a CD drive at all?
Ask the hospital or scan center for another format. You don't need to buy anything first.
- ✓A download link or patient portal. Many centers can share your images online. Ask for the DICOM images, not only the PDF report.
- ✓A USB pen drive. Some centers will copy the study onto one for you.
- ✓A USB CD/DVD drive. An inexpensive external drive works with most laptops and Macs.
- ✓A friend's computer. Copy the whole disc to a pen drive, then open it at home.
How do I keep my scan private?
Treat your scan like any other medical record. DICOM files carry your name, date of birth, hospital and scan details inside them, not just the pictures.
- •Use your hospital's own portal or well-known software from the maker's website.
- •Don't upload your scan to unknown websites that offer to "open" or "convert" DICOM files.
- •Only run the program on the disc if the disc came straight from your hospital or scan center.
- •When you share a scan, share it with a doctor or service you chose on purpose.
What can I learn from looking at my own scan?
The viewer shows images, not a diagnosis. The radiologist's report is what explains them.
Radiologists train for years to read these images. They look at every slice, in several directions, with settings for bone, lung or soft tissue, and they compare with older scans. Shapes that look alarming are often normal anatomy. Please don't draw conclusions from the pictures alone. Take your questions to your doctor.
At 5C, our radiologists read scans in RadDream, 5C's web DICOM viewer, which runs in the browser. It is the professional tool they report in, not an app for patients to download.
5C SecondRead
Want a specialist to look again?
Upload the CT, MRI, X-ray or mammogram you already have. A super-specialist radiologist re-reads it independently and you get a signed, written report to discuss with your doctor. No new scan, no radiation.
Get a specialist second opinionFor hospitals and diagnostic centers: see RadDream, 5C's web DICOM viewer.
Frequently asked questions
Why can't I open my CT or MRI CD on my Mac?
There are usually two reasons. Most current Macs have no CD drive, so you need a USB CD/DVD drive or a copy of the disc on a pen drive. And the viewer on most scan CDs is a Windows program, so it won't run on a Mac. The images themselves are standard DICOM files: install a Mac DICOM viewer such as Horos or Weasis (both free and open source), then import the disc or folder.
What is the DICOMDIR file on my scan CD?
DICOMDIR is an index file. It lists every patient, study, series and image on the disc and where each file sits, so a viewer can show your scan in the right order. It is not an image itself. When a viewer asks you to open a disc, pointing it at the DICOMDIR file (or the CD drive) is usually the quickest way.
Can I open DICOM files on my phone?
Sometimes, but a computer is easier and safer. A scan CD can hold hundreds or thousands of image files, and phones have no CD drive. If your hospital or scan center has a patient portal, its link may open your images in a phone browser. If you try a phone app, use one from a known developer, read what it does with your data, and avoid apps that ask you to upload your scan to their servers.
Is it safe to upload my scan to a website?
Your scan is personal health data. Its files carry your name, date of birth and other details. Only upload it to services you trust and have chosen on purpose, such as your hospital's own portal or a known second-opinion service. Don't upload it to random free websites that promise to open or convert DICOM files.
How do I send my scan to a doctor?
Ask the doctor how they prefer to receive it. Many accept the original CD, or a pen drive with a full copy of the disc. If the scan center gave you a portal or download link, you can often share that. If you want a specialist radiologist to read the images again, 5C SecondRead lets you upload the scan you already have and returns a signed written report.
Why does my scan look different from what the report says?
The viewer shows images, not a diagnosis. Radiologists read every slice, in several planes, with brightness and contrast settings tuned for bone, lungs or soft tissue, and compare them with your history and older scans. Something that looks worrying to an untrained eye can be normal, and real findings can be invisible without the right settings. The radiologist's report is what explains the images. Talk it through with your doctor.
The CD from my scan center is empty or won't read. What now?
Try another computer or another CD drive first. Discs scratch easily and some drives struggle with them. If it still fails, contact the hospital or scan center. They keep your images and can usually burn a new disc, copy them to a pen drive, or give you a download link.
