.dcz is extension for DynaCAD. So I it's some sort of image generated with a CAD program (medical MRI scan?), so you need that CAD program or other compatible CAD program to open it. BTW, if it's important medical images, I'll get medical imaging specialist for help.
thanks so much. the photos were moved from a hard drive to an external hard drive and suddenly appeared and .dcz on the external hard drive. I may have to go back to the original hard drive to see if they are still there. The photos are of my son with his father - nothing sinister at all - they are getting around on a ride on lawn mower doing a plumb raid in the orchard. So if there is a way to get them back I would like to know it for sentimental reasons. I see this is the answer to a question in the post above.