How to view your CT / MRI scan CD in your browser - stream or open it, phone or PC, no upload

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What the demo scans show

The demos show a left superior semicircular canal dehiscence (SCDS) - my own diagnosis, which is why I built this tool. So you can match what you see against a real reading, here are excerpts summarized from the professional radiology reports of these exact scans (identifying details removed):

• CT temporal bone - “A focal bony dehiscence at the superoposterior aspect of the left superior semicircular canal.” The right inner ear is unremarkable. Open the thin-slice IAC Lt cor/sag oblique 0.6 mm series (the reformats along the canal) and pick the Bone window preset.
• MRI brain / base of skull - reviewed for the same: “suspected focal thinning of the bony coverage at the posterior aspect of the left superior semicircular canal; dehiscence cannot be excluded”, with incidental sinus changes. Clinical picture: chronic dizziness.

Download the full CDs (GPL)

I release both anonymized scans under the GNU GPL v2 (same license as the site’s tools) - free to use for testing, learning and demos. Each is the complete CD as a zip, with a LICENSE.txt inside. Streaming is instant; downloading gives the smoothest scrolling if you open the file locally.

• Download the full CT temporal-bone CD (~1.2 GB zip, GPL)
• Download the full MRI brain / base-of-skull CD (~870 MB zip, GPL)

Open your own scan

1. Get the CD as a zip (hospitals often also give a zip download; or zip the CD folder). An unzipped folder or loose .dcm files work too.
2. Open https://www.clearevo.com/dicom/, hit Open (or drag the zip onto the page). On a phone: save the zip (from your hospital link), then pick it from Files.
3. Pick a series from the thumbnail list on the left.
4. Browse the way the desktop viewers do: mouse wheel / slider / arrow keys for slices; W/L drag for brightness/contrast (with CT presets - soft tissue, brain, lung, bone); Pan, Zoom, 📏 Measure (distance in mm), Tags (every DICOM tag).
5. On a phone it’s a photo app: swipe through slices, pinch to zoom, drag to pan when zoomed, double-tap to zoom.

The interface is available in English and ไทย (auto-selected from your browser; switch with the language box).

How streaming a gigabyte CD works (the SL45 trick)

A full CD is often a gigabyte-plus zip with thousands of slices. The viewer never downloads it. It reads the CD’s built-in DICOMDIR index (one file listing every series and image), then pulls only the slices you actually look at, straight from the server via HTTP range requests - with the next slice prefetched. Opening the 1.2 GB demo CT reads about 6 MB to show the first image, not 1.2 GB.

That’s the same approach I used back in 2003 on the Siemens SL45 for the Bangkok bus pathfinder (a Sun Microsystems Java contest winner): the phone’s KVM had almost no RAM, so all the bus stops and routes lived in indexed files and were read through tiny buffers - index first, then read only the buffer the current view needs. The same idea, twenty years later, streams a whole scan CD to your phone.

A local file works the same way (reading from disk instead of the network), so there’s no size limit for opening your own CDs.

Honest limits

• Decodes uncompressed DICOM, JPEG Lossless (most CT/MRI CDs) and standard JPEG (common for ultrasound). JPEG 2000 and RLE CDs aren’t supported yet - if yours won’t open, tell me in the comments.
• Multi-frame cine clips show their first frame only for now.
• Google Drive folder integration is planned; for now, download the zip first.
• Not a medical device: this is for looking at your own scans - diagnosis belongs to your radiologist and their certified tools.

Everything is client-side (Google Analytics for visit stats only - verify).

This tool is free software and open source: ykasidit/web_fun - issues and pull requests welcome. The demo CT/MRI scans are my own, anonymized, and released under GPL v2.

Full disclosure: this post - and any code or tool it describes - was co-authored with Claude (Anthropic’s AI, via Claude Code). I directed, guided and reviewed - though I have not personally tested every tool in every case; Claude wrote most of the code and most of the text. I don’t want to pretend otherwise.