What is a DICOMDIR file?
Almost every disc from a hospital has a file called DICOMDIR at the top. It looks like the thing to open — but it holds no pictures at all.
An index, not an image
DICOMDIR is a table of contents defined by the DICOM standard for removable media. It lists the patients, studies and series on the disc, and for each image the path of the file that holds it. The images themselves are separate files, usually in a folder named DICOM, IMAGES or a code like S0001.
That is why opening DICOMDIR alone shows nothing: there are no pixels inside it. Programs that read it then go and fetch the files it points to — which only works when the whole disc is there.
How to open the images
- Copy the whole disc to your computer, keeping the folders as they are.
- Drag the copied folder — not the
DICOMDIRfile — onto OsonKit. On a phone, choose all the files in the folder at once. - OsonKit reads the header of every file and sorts the images into patients, studies and series. It does not need the
DICOMDIRfor that and skips it.
If you open the DICOMDIR by itself, OsonKit tells you that it is a study index and asks for the folder.
Files without extensions
Image files on such discs often have names like IM000123 or 00000001 with no extension, so your computer does not know what they are. That is normal. OsonKit recognises DICOM by the content of the file, not by its name.