DICOM is an acronym for Digital Imaging and Communications in Medicine. Files in this format will likely be saved with a DCM or DCM30 (DICOM 3.0) file extension, but some may have no extension at all.
Part 1, OnDemand 3D CBCT Software, Importing DICOM Dataset, by Dr. Khaled Ekram (in English)
DICOM is both a communications protocol and a file format, meaning it can store medical information, such as ultrasound and MRI images, along with a patient’s information, all in one file. The format keeps all of the data together and allows said information to be transferred between devices that support the DICOM format.
DCM or DCM30 files that you find on a disk or flash drive that you received after a medical procedure can be viewed with the provided DICOM viewer software that is also found on the disk or drive. Look for a file called setup.exe or something similar, or consult the documentation that came with the data.
If you can’t get the DICOM viewer to work, or if your medical images didn’t come with one, the free program MicroDicom is an option. It allows you to open the x-ray or other medical image directly from the disk, via a ZIP file, or even by having the program search your folders for the DICOM files. Once one is opened in MicroDicom, you can view the metadata, export it as a JPG, TIF, or other common image file type, and more.