He's not talking about word processor files, but about data from other stuff. How do people open XRays or MRI scans or etc etc?
(And even word processors have problems when trying to open some obsolete format.)
(And even word processors have problems when trying to open some obsolete format.)
Essentially all modern medical scanners export data in this format.
This fantastic site will let you view (after upload) DICOM images in a web browser:
There are a number of accessible (ie not clinical radiology priced) viewers available, the best of the lot for general use being Osirix [1] (OS X only), and ClearCanvas [2] (Windows only). Ginkgo CADx [3] and Mint viewer [4] are also good, and both cross-platform.
There are several well-regard open-source libraries for DICOM: gdcm [5] and DCMTK [6]. Widely used open-source medical image visualization SDKs with DICOM support include MITK [7] and 3D Slicer [8] (the afore-mentioned ClearCanvas is also an SDK in some sense).
[edit: formatting and add link]
1. http://en.wikipedia.org/wiki/OsiriX
2. http://www.clearcanvas.ca/dnn/
4. http://www.mint-medical.de/
5. http://en.wikipedia.org/wiki/GDCM