Files with the .DCM extension contain digital medical images as well as patient information, encoded in the standardized DICOM format, which is short for Digital Imaging and Communications in Medicine.

The format allows for the saving of medical examination images, such as magnetic resonance imaging, or MRI for short, computer tomography, also known as CT, as well as ultrasonography, abbreviated as USG. The DCM format was introduced by the NEMA, which is short for National Electrical Manufacturers Association, for the purposes of establishing a homogenous method for storing examination images and patient information, as well as examination descriptions.