What is a DICOM file?#
Step 1 — What the letters mean#
Think of DICOM as a contract: manufacturers agreed on how to store medical images so any hospital system can exchange them. Your disc might say "DICOM" on the sleeve even when the filenames look like IM0001 with no extension.
Step 2 — What is inside one file#
Beyond the grayscale picture you eventually see, the file carries technical notes: how thick the slice is, which direction you are looking from, sometimes the MRI sequence name, and patient identifiers unless someone anonymized the study. That is why sharing "just one slice" can still leak private data.
Step 3 — Why Preview, Photos, or Paint fail#
Consumer apps expect color photos. DICOM often uses 12–16-bit grayscale and needs a viewer that understands the header. OpenMyScan reads the folder locally and rebuilds the stack so you can scroll.
Step 4 — Tools that actually open DICOM#
Hospitals use heavyweight clinical workstations. At home, our free DICOM viewer runs in a browser without installing anything; desktop alternatives exist but often look like cockpit dashboards. Pick the option you can actually navigate calmly.
What confuses people first encountering DICOM?#
- I only see gibberish icons
- You are probably in the wrong app — drag the folder into OpenMyScan instead.
- Which file do I open first?
- None individually — select the parent folder that holds them all.
- Is DICOM the same as a radiology report PDF?
- No. The PDF is words from the doctor; DICOM is the raw images.
- Someone said DICOMDIR — what is that?
- A table of contents file; keep it beside the slices so software can load the whole study.
Common questions#
Is DICOM secure?
The format is not encrypted by default. Protect USBs and cloud links the same way you would any medical document.
What's the file size?
One slice might be a few hundred kilobytes; entire studies often range from tens to hundreds of megabytes.
Do all hospitals use DICOM?
Modern imaging centers export DICOM routinely; if you received a CD, it almost certainly contains DICOM or a viewer pointing to it.
Can I view my scan on my phone?
No. OpenMyScan needs a wider screen to show images alongside the series list — use a laptop, desktop, or tablet in landscape. Phone support is not planned.