“Imaging” is a general term used instead of “taking x-rays,” because there are other ways to take pictures inside the body. X-rays employ radiation, which may have dangers if overused, although it’s very little (see Radiation Risks of X-rays). CT scans employ a lot more radiation than plain x-rays. Magnetic Resonance Imaging (MRI) doesn’t use any radiation, but is more expensive, takes a lot longer to do, can’t be done on people with metal inside them (pacemakers, bullets, etc.), and can’t be used for certain indications. Ultrasounds (also called “sonograms”) use sound waves, no radiation, but often can’t see as much as a CT scan or MRI can.