A DICOM backup for a dental clinic comes down to one rule: keep at least three copies of every CBCT and X-ray study, on two kinds of storage, with one copy outside the building and disconnected from the clinic network, and prove that you can restore from it. This guide applies that plan, usually called 3-2-1, to a small practice that keeps its images on a DICOM server such as Orthanc. Sources were checked on 19 October 2026. Status: Not tested yet — the steps follow the official documentation; we have not run a restore on a clinic network.
A note on the rule itself: neither of the official sources used below prints the words “3-2-1”. It is a widely used planning habit, not a standard, and what follows is our way of organising the official advice. Nothing here is legal advice, and clinics outside the US should check their own retention and privacy rules.
The 3-2-1 plan at a glance
| Copy | Where | Purpose |
|---|---|---|
| 1 — live data | The imaging server’s own disk | What the clinic works from every day |
| 2 — local backup | A different device in the practice (external drive or NAS) | Fast restore after a disk failure or a deleted study |
| 3 — off-site, offline | Encrypted media or storage kept away from the practice network | Survives fire, theft and ransomware that reaches the network |
“Two kinds of storage” means the live disk and the backup should not be the same technology or the same device. A second folder on the same drive is not a backup.
Step 1: Know what you must copy
For Orthanc with its default SQLite storage, the Orthanc Book names three things: the configuration file, the DICOM files, and the SQLite index. The DICOM files live in subfolders of the storage folder, and the index is the index* files next to them. Copying only the images without the index leaves you with files Orthanc does not know about.
If you use a different archive, such as dcm4chee Archive, which runs with a separate database and directory service, the list is longer: the image storage, the database and the configuration all need copies. Follow that project’s own documentation for the exact parts. If your imaging software keeps studies in its own database instead of a DICOM server, ask the vendor in writing where the images and the patient index live and how they are exported.
Whatever you run, also keep the list of your imaging units with their AE titles, ports and IP addresses. After a rebuild it saves hours.
Step 2: Take a consistent copy
The Orthanc Book explains that the Orthanc core assumes it is the only process using the SQLite database, so for SQLite the documented procedure is: stop Orthanc, copy the configuration, the DICOM files and the index, then restart it. For a clinic this means a scheduled window outside opening hours, with the service stopped automatically before the copy job and started after it.
If you cannot stop the server every night, the same page points to the PostgreSQL and MySQL/MariaDB back ends, where the database can be backed up while Orthanc runs, using that database’s own tools. The cost is more moving parts to look after. For a single-chair practice, a short nightly stop is usually simpler. Our Orthanc setup guide covers installation and the security settings.
If the database and the image files are copied at slightly different moments, they can disagree. After a restore, the Orthanc Book suggests re-sending the last day or so of studies from the imaging units with OverwriteInstances set to true, so that anything missing is rewritten. Your units must still hold those recent studies, so do not clear a unit’s local storage on the day of a restore test.
Step 3: Make the local copy
- Choose a device that is not the imaging server: an external drive that is attached only during the job, or a NAS used for nothing else.
- Run the stop-copy-start job on a schedule and write the result to a log someone reads.
- Keep several dated versions instead of one folder that is overwritten each night. A study deleted by mistake on Monday is gone from an overwritten copy by Tuesday.
- Do not leave the backup share permanently mounted and writable from every workstation. The CISA ransomware guide warns that ransomware variants often try to find and delete or encrypt backups that are reachable.
Step 4: Make the off-site, offline copy
The CISA guide recommends keeping offline, encrypted backups of critical data. For a small clinic there are two practical ways to do that:
- Rotating encrypted drives. Two or three drives, one always away from the practice, swapped on a fixed day. Encrypt the drive, and store the recovery key separately from the drive.
- Encrypted cloud or remote storage. Acceptable if the data is encrypted before it leaves the clinic and the provider’s terms fit your privacy rules. Check this with whoever handles your compliance. The Orthanc Book itself advises getting local legal advice before putting patient images in the cloud.
CISA also notes that immutable storage should be used with caution, because it may conflict with some regulatory requirements and a mistaken setting can be costly to undo. Decide the retention period for images first, then configure storage to match.
Step 5: Replication is not a backup
The Orthanc Book describes ways to replicate studies from one Orthanc server to another, for example for upgrades or a mirrored server, including a script that uses the REST API, and a Transfers accelerator plugin for moving studies between peers. A second server that receives every study is useful for availability, but it is not an offline backup: a deleted or encrypted study can be copied across just as easily. Treat a mirror as an extra, not as the “one copy elsewhere”.
Step 6: Test the restore
CISA’s advice is to test backup procedures on a regular basis, and to check availability and integrity in a disaster recovery scenario. For this plan, a restore test means:
- Install the same Orthanc version on a spare machine, never on top of the live server.
- Restore the configuration, DICOM files and index from the off-site copy. Stop Orthanc while the database is restored.
- Open a few recent and a few old studies in the web interface and compare the study count with the live system.
- Write down how long it took and what was missing. That time is your real recovery time.
Repeat after any major upgrade and at least once a year. An untested backup is a hope, not a plan.
A routine checklist
| When | Task |
|---|---|
| Every night | Automatic stop-copy-start job finishes; log shows no errors |
| Weekly | Someone checks the log and the free space on the backup device |
| Weekly or fortnightly | Swap the off-site drive or confirm the remote upload completed |
| After each upgrade | Take a manual copy first; keep it until the new version has run for a while |
| Yearly (or more often) | Full restore test on a spare machine |
For the wider picture of free imaging servers and viewers, see free dental imaging software.
Limitations
- Not tested yet: we have not run these steps ourselves; the procedure follows the Orthanc Book and the CISA guide.
- The Orthanc Book’s exact wording on stopping the server for SQLite copies has changed over time. Read the current backup page before you write your script.
- The plan does not replace your imaging vendor’s instructions if images live in a proprietary database.
- HIPAA and other legal obligations on retention, encryption and breach handling depend on your jurisdiction. NIST publishes a general implementation guide for the HIPAA Security Rule (SP 800-66 Rev. 2), but this article is not legal advice.
FAQ
How do I back up DICOM images?
Copy the image files together with the database or index that tracks them, on a schedule, to a second device and to an off-site offline copy. For Orthanc with SQLite that means the configuration, the DICOM files and the index files, copied while the service is stopped.
How do I back up CBCT data?
Treat CBCT studies like any DICOM study: if they are in a DICOM server, back up the server as above. If they sit in the imaging software’s own database, ask the vendor how to export or back up both the images and the patient index.
Can I back up Orthanc while it is running?
With the default SQLite storage the documented procedure is to stop it first. With PostgreSQL or MySQL/MariaDB the database can be backed up while Orthanc runs, using that database’s tools.
What do I do after restoring an Orthanc backup?
Stop Orthanc while the database is restored, and if the files and database were copied at different times, resend the last day of studies from your imaging units with OverwriteInstances set to true.
Is a second server or a NAS enough?
No. A second server or NAS that is always online and writable can be encrypted or deleted along with the first. Keep one copy offline and away from the practice.
Last updated: 19 October 2026 · DentIIT editorial team. Licence, version and platform details are checked against each developer's official documentation; none of the tools listed here should be treated as a certified medical device unless its vendor says so.
