Open a CT scan CD with nothing to install
When a head or face CT scan comes on a hospital CD or USB stick, it holds a DICOMDIR, the DICOM images and often a Windows viewer. tresD DICOM opens the images in your browser, also on a Mac, without that viewer and without uploading the study anywhere.
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What is on the disc
If there is no DICOMDIR anywhere on the disc, it is probably not a DICOM disc: some hold the study only in their viewer’s own format or as JPEG pictures. In that case, ask the hospital for a copy in DICOM.
Which series to choose
A CT study usually has several series: the scout or topogram (the planning image), axial slices with soft-tissue and bone filters, sometimes thin and thick slices, coronal and sagittal reconstructions and even a dose report. When you open the folder, tresD DICOM shows them in the «Several series in the folder» window with their name, orientation and number of slices, the one with most slices first; you can switch series later from the left panel.
For 3D, the panoramic and the TMJ, the original thin-slice axial series (1 mm or less) is best, and it is usually the one with most slices. Coronal or sagittal reconstructions and thick-slice series are for looking at slices, not for 3D. If the series was acquired with a tilted gantry, it may look distorted in 3D: in that case, ask the radiology department for the axial series without tilt.
Step by step
Copy the disc to your computer
Copy the whole content of the CD or USB stick into a folder, for example on the desktop. Reading straight from the CD is slow and can fail halfway through loading. There is no need to open the disc viewer.
Open tresD DICOM
Go to tresddicom.com/app with Chrome, Edge, Safari or Firefox. No sign-up and nothing to install.
Choose the whole folder
Click «📁 DICOM folder» and choose the folder you copied the disc into, the one holding the DICOMDIR. You can also drag it onto the window. tresD DICOM picks out the images and leaves the viewer program aside.
Choose the series
If there are several, the «Several series in the folder» window appears: keep the axial one with most slices selected and click «Open». Slices appear while the files arrive.
If it does not open
«The rest of the CD is missing» appears
You chose only the DICOMDIR file, which is the index. Choose the whole folder that contains it.
«This is not the CBCT» appears
You chose the folder of the viewer program on the disc (nearly all .dll and .exe files). The images are in another folder of the same disc: choose the one holding the DICOMDIR.
It says it cannot find DICOM images
The disc does not hold DICOM, but its viewer’s own format or JPEG pictures. Ask the hospital for a copy of the study in DICOM.
The volume looks stepped or has few slices
You opened a thick-slice series or a reconstruction. Switch to the axial series with most slices from the left panel.
What you can do next
With the CT open you have the axial, coronal and sagittal slices, the 3D render, the panoramic, cross-sections per tooth, the TMJ, the airway, the simulated cephalogram and the superimposition of two studies of the same patient, and what you see goes into a PDF or PowerPoint report. All measurements are indicative. See all features.
Common questions
Do I need the viewer that comes on the disc?
No. tresD DICOM reads the DICOM images on the disc directly in the browser, on Windows, Mac and Linux. On a Mac, the disc viewer, which is usually Windows-only, will not help.
Which series do I open for 3D?
The original thin-slice axial series (1 mm or less), which is usually the one with most slices.
Does it open CT scans with compressed images?
Yes: on DVDs and USB sticks they are sometimes compressed as lossless JPEG or JPEG 2000, and tresD DICOM reads them.
Is the CT uploaded to the internet?
No. The files are read and processed on your own computer; they are not sent to any server.
Is it free?
Yes: no sign-up, no licences and no limit on studies.
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