Platform & software · DICOM viewers

DICOM viewer software: which DICOM image viewers are FDA cleared for diagnostic reading

The short answer

A DICOM viewer is software that opens and displays medical imaging studies stored in the DICOM format, and the single question that separates one product from another is whether it is cleared by the FDA for diagnostic reading. In the United States, viewers intended for interpretation are regulated under 21 CFR 892.2050 as a medical image management and processing system, a Class II device, most often under product code LLZ. As of the openFDA pull behind this page on August 31, 2026, 2,285 devices have been cleared under LLZ, 93 of them since the start of 2025. The widely downloaded free viewers are not among them. MicroDicom states on its own product page that it "has no CE mark (EU) or FDA approval (USA) nor any other national or international approval as medical device", and the RadiAnt license agreement states that "The Program (including the Program with the key) is not certified as medical product". Those are the vendors talking about their own software, not our opinion. So the practical rule is simple: a free desktop viewer is fine for looking at a study you did not report, and a cleared viewer is what you read from.

Search for DICOM viewer software and you get a list of free downloads. Almost none of the pages ranking for that term mention the one fact that decides whether a radiology practice can use any of them, which is regulatory status.

The distinction is not subtle and it is not a marketing gray area. Viewers sold for interpretation go through FDA review; viewers given away for looking at images do not, and their own license agreements say so in plain language. MicroDicom's product page says the program has no FDA approval and is "therefore not to be used for clinical purposes and in any way to affect patient management". RadiAnt's end user license agreement says the program is not certified as a medical product and is not to be used in diagnostic decision-making or to interpret and report imaging studies. Even the open source lineage is split down the middle: OsiriX MD was cleared in 2010 under K101342, while OsiriX Lite is not intended for primary diagnostic use, and Horos MD reached clearance as K232589 in January 2024 while the free Horos build did not.

That matters commercially because the two products cost wildly different amounts and solve different problems. A referring physician who wants to glance at a chest film needs a browser tab. A radiologist signing a report needs software whose manufacturer has told the FDA what it is for, running on a display calibrated to the DICOM grayscale standard display function, inside a workflow your accreditation body will accept.

What follows sorts the market into the four things people mean when they say DICOM viewer, then gives the actual FDA record: cleared products, K numbers, decision dates and the applicant on the submission, pulled from the openFDA 510(k) database on August 31, 2026 so you can check every row yourself.

Last updated August 2026

The Reading Station

Assistant ready

Worklist

SERIES 1 · AX

SLICE 24/64

SAMPLE STUDY

NOT FOR DIAGNOSTIC USE

W 80 · L 40

Structured report

Draft

Run the assistant to draft this report for review.

You review & sign

Illustrative sample · not a real patient study, not a diagnosis

Drafted in · you review & sign Worklist re-prioritized

Decision support for qualified clinicians. Radiological.ai does not provide a diagnosis and is not a substitute for professional judgment.

Run the assistant

Flag · prioritize · draft · you review and sign

X-RAY CT MRI BUILT WITH RADIOLOGISTS

Decision support not a diagnosis

You review & sign

A viewer is one layer of a larger stack, and buying the wrong layer is the common expensive mistake. If the real problem is where studies live and how they survive a vendor change, that is enterprise imaging and vendor neutral archive software, where the universal viewer is ranked as its own separate category. If the problem is the reading platform the radiologists work in all day, that is PACS software and PACS system vendors compared by study volume. The operational half, meaning scheduling, worklists and charge capture, is radiology information system software.

On the regulatory side, the same 510(k) database behind the table on this page also drives our page on the FDA approved AI medical device list for radiology, which covers the triage and detection product codes rather than the image management code that governs viewers, and explains the four step procedure for verifying any K number before you sign. For budget, radiology software pricing breaks federal contract data down by software category. Groups reading across sites they do not own usually hit image distribution before they hit display, which teleradiology software works through, and radiology AI PACS integration over DICOM and HL7 covers how anything else reaches the reading path at all.

Side by side

The four things people mean by DICOM viewer software

These are four different products at four different prices, and the word viewer is used for all of them. Work out which row of the buying decision you are in before you compare anything, because a free desktop viewer and a cleared diagnostic workstation are not competing for the same job.

What you are comparing	Free desktop viewer	Cleared diagnostic viewer or workstation	Zero footprint or enterprise viewer	The viewer inside your PACS
What it is for	Opening a study on a CD or a downloaded folder, teaching, research and personal review	Primary interpretation: the study a radiologist reads and signs a report from	Showing studies to clinicians outside radiology, normally in a browser with nothing installed	The reading application your radiologists already use, bundled with the archive underneath it
Regulatory status in the United States	Generally none. Vendors state this themselves rather than leaving it implied	Cleared under 21 CFR 892.2050, Class II, usually product code LLZ, with a K number you can look up	Split. Some are cleared for diagnostic display and some are explicitly reference only, sold side by side by the same vendor	Cleared, because the diagnostic viewing component is part of what the PACS submission covers
What the vendor actually says	MicroDicom: "has no CE mark (EU) or FDA approval (USA) nor any other national or international approval as medical device". RadiAnt: "The Program (including the Program with the key) is not certified as medical product"	The Indications for Use statement filed with the 510(k), which names the modalities and the intended reader	Read the datasheet footnote. "For reference use only" and "cleared for diagnostic use" appear in the same product family	Covered by the PACS clearance, but confirm the specific version and module you are licensing
Verified examples with K numbers	Not applicable. MicroDicom, RadiAnt, Weasis, OsiriX Lite and the free Horos build carry no clearance	OsiriX MD K101342, Horos MD K232589, FlexView Diagnostic K233226, Visage Ease Pro K142196	eUnity K172490, Ambra ProViewer K202335, Merge Universal Viewer K250301, Change Healthcare Enterprise Viewer K181185	IntelePACS K192176, Ambra PACS K231360, Sectra Workstation IDS7 K081469, Visage PACS K082269
What it costs	Nothing, which is exactly why it is the wrong tool for the job it keeps getting used for	Per named reader or per concurrent seat, annually, quoted rather than published	Usually per site or per named user, and often bundled into an archive or exchange contract	Inside the PACS subscription, so the marginal cost of one more reading seat is a line in that contract
Display requirements that come with it	None. A laptop screen is fine for the job it is licensed for	A diagnostic interpretation display calibrated to the DICOM grayscale standard display function, per the ACR and AAPM technical standard	Consumer displays are normally acceptable, because the use is review rather than primary interpretation	Same diagnostic display requirements as any primary reading station
Who buys it	Individual clinicians, students, patients and researchers	Radiology groups, imaging centers and teleradiology practices that sign reports	Health systems that need referring physicians and specialists to see images without a PACS seat	Anyone who already runs a PACS, which is the majority of the market
The mistake this tier causes	Reading and reporting from software whose license explicitly forbids it, which is an accreditation and liability exposure long before it is an FDA one	Buying diagnostic seats for people doing review work, which is the most common way viewer spend gets inflated	Assuming zero footprint means diagnostic. It does not; it describes deployment, not clearance	Assuming the PACS viewer covers everyone, then discovering referring physicians need seats you did not budget
Where an AI assistant attaches	Nowhere. There is no workflow here to attach to	Here, alongside the reading application rather than inside it. Radiological.ai flags suspected findings for a second look and drafts the structured report	Not here. A review viewer displays; it does not analyze	Here, through the PACS over standard DICOM and HL7 interfaces

Compiled August 2026. Regulatory statements are quoted from each vendor's own published product page or license agreement, and clearance records are from the openFDA 510(k) API, product code LLZ, queried on August 31, 2026. Product code counts move as new clearances post, so re-run the query rather than quoting this page as a current figure. Vendor names are examples of who sells into each tier and are not an endorsement or a shortlist. Nothing here is legal or regulatory advice; confirm your own obligations with your accreditation body and counsel.

Primary source

DICOM viewers with a verified FDA 510(k) clearance

Every row below is a real record in the FDA 510(k) database, pulled through the openFDA API on August 31, 2026 under product code LLZ. Look any of them up by K number at accessdata.fda.gov. This is not a ranking and it is not a shortlist. It is the answer to one narrow question a lot of buyers never ask, which is whether the software you are being sold has actually been through review.

Product as filed with the FDA	Applicant on the submission	K number	Decision date	Product code
AdvaView	AdvaHealth Solutions	K262449	2026-08-14	LLZ
ImageGrid StreamVue	Candelis	K262143	2026-07-23	LLZ
Avara Viewer	Avara Software	K262120	2026-07-10	LLZ
ResolutionMD	ResolutionMD, Inc.	K260500	2026-07-21	LLZ
Merge Universal Viewer	Merge Healthcare	K250301	2025-04-14	LLZ
Horos Mobile	Icat Solutions	K242552	2025-04-08	LLZ
aiCockpit AI Viewer	Fovia	K241546	2025-02-26	LLZ
FlexView Diagnostic	Radical Imaging	K233226	2024-01-17	LLZ
Horos MD	Icat Solutions	K232589	2024-01-03	LLZ
Ambra PACS	Ambra Health	K231360	2023-06-07	LLZ
Ambra ProViewer	Ambra Health	K202335	2020-09-04	LLZ
IntelePACS	Intelerad Medical Systems	K192176	2020-04-02	LLZ
Change Healthcare Enterprise Viewer	Change Healthcare Canada	K181185	2018-08-29	LLZ
eUnity	Client Outlook	K172490	2018-02-06	LLZ
Visage Ease Pro	Visage Imaging	K142196	2015-04-28	LLZ
OsiriX MD	Pixmeo	K101342	2010-08-20	LLZ
Sectra Workstation IDS7	Sectra Imtec	K081469	2008-06-12	LLZ

Source: openFDA 510(k) API, product code LLZ, queried August 31, 2026. The list is a sample of recognizable products, not the full 2,285 devices cleared under this code. A clearance is specific to the version and the Indications for Use filed at the time, so an old K number does not tell you the current release is unchanged. Ask the vendor which K number covers the exact version and modules you are buying.

Why it works

What your group gets with DICOM viewers

Clearance is a claim about the manufacturer, not a permission slip for you

FDA clearance governs what a company may market its software to do. It does not regulate a physician directly. That is why nobody gets a letter from the FDA for opening a study in a free viewer. The exposure sits elsewhere and it is more practical: accreditation programs and payers expect primary interpretation on qualified equipment, and a plaintiff attorney reading a license agreement that says the software is "not certified as medical product" has an easy paragraph to write. Use the free viewer for the job its license describes.

Zero footprint describes deployment, not clearance

A zero footprint viewer runs in a browser with nothing installed. That is an IT property. It says nothing about whether the product is cleared for diagnostic reading, and vendors sell both kinds under names that look identical on a datasheet. eUnity, Ambra ProViewer and the Merge Universal Viewer all hold their own 510(k) clearances. Plenty of browser viewers do not. Ask for the K number and the Indications for Use text, not the marketing sheet.

The assistant sits beside the viewer, not inside it

Radiological.ai is not a DICOM viewer and it does not replace one. It connects to the PACS you already run over standard DICOM, flags suspected findings for a second look, pushes time-critical studies up the worklist and drafts the structured report into your template. It is decision support. The responsible radiologist opens the study in whatever cleared viewer you use, reviews, edits and signs.

What it handles

Flagged, prioritized and drafted for your review

The assistant pre-reads each study, surfaces a region of interest for review, re-prioritizes the worklist, and drafts the structured report in your template. You confirm, edit and sign.

Works with the viewer and PACS you already run
Connects over standard DICOM and HL7 interfaces
Flags suspected findings for a second look
Reorders the worklist so urgent studies surface first
Drafts the structured report into your template
No change to your reading application or display setup
Radiologist reviews, edits and signs every study

DICOM VIEWERS STAT

Region of interest flagged for review

A focal region is surfaced on the sample study for the radiologist to review. The assistant does not characterize it as a diagnosis.

Draft impression

Suspected finding flagged for radiologist review. Correlate clinically and confirm. Draft for review and sign-off.

Illustrative sample · not for diagnostic use You review & sign

Why Radiological.ai

One assistant across the whole read

Not three vendors stitched together. Flag, prioritize and draft in one calm pane, on X-ray, CT and MRI, with the radiologist signing every study.

Flags suspected findings

A second set of eyes surfaces regions of interest for review on every study, so a suspected finding is less likely to slip past late in a shift.

Prioritizes the worklist

Suspected-critical studies move to the top, so urgent reads surface ahead of routine follow-ups across your sites and shifts.

Drafts the report

A structured draft arrives in your template, ready to edit and sign. The draft saves the typing and the measuring, never the judgment.

Good questions

Questions about DICOM viewers

A DICOM viewer is software that opens medical imaging studies saved in the DICOM format, the standard every CT, MRI, ultrasound and X-ray system writes. At minimum it displays the images and the study metadata. Diagnostic viewers add windowing, measurement, multi-planar reconstruction, hanging protocols and comparison against prior studies, which is the difference between looking at a study and reporting one.

There is no single best one, because the tiers do not compete. For primary interpretation you need a viewer cleared under 21 CFR 892.2050, which includes products such as OsiriX MD, Visage Ease Pro, FlexView Diagnostic and the viewers inside IntelePACS and Sectra IDS7. For browser-based review across a health system, eUnity, Ambra ProViewer and the Merge Universal Viewer all hold their own clearances. For opening a study on a CD, a free desktop viewer is the right tool. Pick the tier first, then compare inside it.

No. MicroDicom says so on its own product page: the program "has no CE mark (EU) or FDA approval (USA) nor any other national or international approval as medical device. It is therefore not to be used for clinical purposes and in any way to affect patient management." The vendor positions it for research, education and personal review. It is a capable viewer for those purposes and it is not a diagnostic reading tool.

No. The RadiAnt end user license agreement states that "The Program (including the Program with the key) is not certified as medical product" and restricts it from use in diagnostic and therapeutic decision-making and from interpreting and reporting imaging studies. That applies to the paid license as well as the free build, which surprises people, because paying for a key does not change a product's regulatory status.

The free Horos build is not, but a cleared product exists under the same name. Icat Solutions holds K232589 for Horos MD, cleared January 3, 2024, and K242552 for Horos Mobile, cleared April 8, 2025, both under product code LLZ. The same split exists in the software Horos was forked from: OsiriX MD was cleared in August 2010 under K101342, while OsiriX Lite is not intended for primary diagnostic use. Check which build you actually installed.

You should not, and the reason is contractual and clinical before it is regulatory. The license agreements of the common free viewers explicitly exclude diagnostic use, so reading from one puts you outside the terms you agreed to. Accreditation programs expect primary interpretation on qualified equipment, and free viewers generally lack the calibration, hanging protocols and prior comparison a reporting workflow depends on. Use them for what they are licensed for.

Ask the vendor for the K number covering the specific version and modules you are buying, then look it up in the FDA 510(k) database at accessdata.fda.gov or through the openFDA API. Read the Indications for Use statement rather than the clearance letter alone, because that is where the modalities, body regions and intended reader are named. If a vendor cannot produce a K number, that is your answer.

In the United States, 21 CFR 892.2050 defines a medical image management and processing system as "a device that provides one or more capabilities relating to the review and digital processing of medical images for the purposes of interpretation by a trained practitioner of disease detection, diagnosis, or patient management." It is a Class II device with special controls. Most viewers clear under product code LLZ, which had 2,285 clearances as of August 31, 2026, with 93 of them since the start of 2025.

A zero footprint viewer runs entirely in a web browser with no software installed on the device, which is why health systems use them to give referring physicians image access without buying PACS seats. Zero footprint describes how it is deployed, not what it is cleared to do. Some carry their own diagnostic clearances, such as eUnity and Ambra ProViewer, and some are explicitly reference only. Confirm which one you are buying.

A DICOM viewer displays studies. A PACS stores them, routes them, manages the worklist and provides the viewer that radiologists read from. Every PACS includes a viewer; not every viewer is a PACS. If your problem is that clinicians outside radiology cannot see images, you need a viewer. If your problem is storage, workflow or reading throughput, you are shopping for a PACS or an archive, which is a much larger purchase.

Usually only for people outside radiology. Your PACS already provides the diagnostic viewer for the radiologists reading in it. The gap that drives a separate purchase is referring physicians, specialists and outside sites who need to see images without a PACS license, which is what universal and zero footprint viewers exist for. Price that against adding PACS seats before you assume a second product is cheaper.

Free viewers cost nothing and are licensed for non-diagnostic use. Cleared diagnostic viewers are quoted rather than published, normally per named reader or per concurrent seat on an annual subscription. Enterprise and zero footprint viewers are usually priced per site or bundled into an archive or image exchange contract. Because none of it is published, the useful move is to ask for the fully loaded first-year total including interfaces and training, then what it renews at in year three.

A diagnostic interpretation display calibrated to the DICOM grayscale standard display function, with a documented quality assurance program behind it. The ACR and AAPM publish the governing technical standards for diagnostic interpretation displays and for the electronic practice of medical imaging, and AAPM Report 270 sets out the display quality assurance procedures. This is the part of the setup that a cleared viewer does not solve for you.

No. Radiological.ai is decision support that works alongside your existing viewer and PACS. It reads the study over standard DICOM, flags suspected findings for a second look, prioritizes the worklist and drafts the structured report into your template. It does not display studies for primary interpretation, it does not store your archive and it does not provide a diagnosis. The responsible radiologist reviews, edits and signs every study.

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