DICOM images are created by sophisticated medical scan equipment. These images are special formats that cannot be read by normal graphics viewers. Therefore, to read DICOM images in Linux, you can use a software called AMIDE in Ubuntu. AMIDE is open source and is available at http://amide.sourceforge.net/
You can install AMIDE to your computer in Ubuntu. Open a terminal window on your computer and enter:
sudo apt-get install amide <enter>
Mileage varies and you should view these files in the original software that was used to create them in the first place.