Orthanc

Orthanc is a free, open-source, lightweight DICOM server: a small PACS that stores medical images, receives them from imaging devices and serves them to viewers. It suits clinic IT staff, small imaging centres and researchers who need a central image archive without an enterprise PACS project. In dental practices it often acts as the shared store for CBCT, panoramic and intraoral studies, with a browser interface on top.

An Orthanc download is available for Windows, macOS and Linux, and as Docker images. It started as research work by Sébastien Jodogne at the University Hospital of Liège. Today it is maintained by Orthanc Team and his research lab at UCLouvain. The core server is licensed under GPLv3 or later; some plugins and viewers use AGPLv3 or later.

Orthanc at a glance

What it does

• Receives images over DICOM (C-STORE, by default on port 4242 with AE title ORTHANC) and sends, queries and retrieves from other DICOM nodes (C-FIND, C-MOVE, C-GET).
• Web interface, Orthanc Explorer 2, for searching, uploading by drag and drop, downloading ZIP archives and forwarding studies.
• Web viewers as plugins: Stone Web Viewer, the OHIF viewer and Kitware’s VolView.
• DICOMweb server and client through the official plugin.
• A full REST API, plus Lua and Python scripting, to automate routing, anonymisation and clean-up.
• PostgreSQL, MySQL/MariaDB and ODBC back ends in place of the built-in SQLite, and cloud object storage.
• An official STL plugin that generates STL meshes from RT-STRUCT or NIfTI volumes and stores STL files in DICOM.
• A Modality Worklist plugin, disk-space recycling and patient protection.

How dental teams use it

A central archive for CBCT and X-ray units

1. Install Orthanc on an always-on clinic computer or server.
2. In your CBCT or imaging software, add a DICOM destination with Orthanc’s IP address, port 4242 and AE title ORTHANC, if the software supports DICOM sending.
3. Send a test study and check that it appears in Orthanc Explorer 2.

Viewing studies from any workstation

1. Keep the viewer plugins selected when you install (the Windows installer selects them by default).
2. Open the web interface, find the patient and open the study in the Stone Web Viewer or OHIF.
3. For desktop viewing, add Orthanc as a DICOM node in Weasis or Horos and query or retrieve studies from it.

Importing discs from referrals

1. In Orthanc Explorer 2, open the upload page.
2. Drag the DICOM files or folder from the disc and click Upload.
3. The study is then available to everyone who has access to the server.

Install and first run

• Windows: run the installer from the official downloads. It installs Orthanc as a Windows service that starts with the computer and lets you choose plugins; all are selected by default. The installer is not code-signed, so SmartScreen may ask you to confirm.
• First login: open http://localhost:8042/ui/app/. The Windows quick-start guide gives the default login; change it straight away.
• Configuration: settings live in JSON files in the Configuration folder of the install directory (for example orthanc.json). Edit them as administrator, then restart the service. One missing comma stops Orthanc from starting, and Windows paths need doubled backslashes or forward slashes.
• Linux: use your distribution’s orthanc package or the official Docker images (orthancteam/orthanc, configured with environment variables, or the minimal jodogne/orthanc).
• macOS: official packages exist for Intel and universal builds.
• Security: by default the web server accepts only local connections. If you allow remote access, turn on authentication. Put Orthanc behind a reverse proxy with HTTPS before exposing it to the internet. Since 1.13.0, Orthanc refuses to start with remote access and authentication on but no users defined.

Limitations

• The project makes no medical-device (FDA or CE) claim. The documentation says security of each deployment is the operator’s responsibility.
• It stores and routes images; it is not a practice management system and has no charting or billing.
• No implant planning or dental-specific tools. The STL plugin works from RT-STRUCT or NIfTI segmentations; it does not segment teeth for you.
• Advanced set-ups (PostgreSQL, authorisation plugin, HTTPS proxy) need someone comfortable with servers and JSON configuration.
• Your imaging units must be able to send DICOM. Some dental software exports only proprietary formats.

Orthanc vs alternatives

FAQ

Where can I get an Orthanc download for Windows?

Official Windows installers, 64-bit and 32-bit, are listed on the Orthanc downloads pages and are provided by Orthanc Team.

Is Orthanc free?

Yes. The Orthanc server is free and open source under GPLv3 or later; some plugins use AGPLv3 or later.

Is Orthanc a PACS?

It is a lightweight DICOM server that covers the core of a PACS: storage, DICOM networking, web access and viewers through plugins.

Which ports does Orthanc use?

By default, 8042 for HTTP and the web interface, and 4242 for DICOM.

Does Orthanc have a DICOM viewer?

Yes, through plugins: the Stone Web Viewer, OHIF and VolView all run in the browser.

How do I run Orthanc in Docker?

Use the official orthancteam/orthanc image and configure it with environment variables, or the minimal jodogne/orthanc image.

Orthanc vs dcm4chee: which should I choose?

Orthanc is simpler to install and run for a single clinic. dcm4chee targets larger, standards-heavy deployments and needs more infrastructure.

Last checked against official sources: 28 September 2026 (developer website: orthanc-server.com). Versions and licence terms change — confirm on the developer's site before deploying in a clinic.