I just ran across the excellent Polite Dissent blog, featuring comics and medicine, among other things.
A search of this blog's archive yields a number of examples of X-rays making it into the comic books.
The Horror of "Lead Lung Disease"
Health Care the Richie Rich Way
Superman using his X-ray vision on Sensor Girl
Dr. Kildare Reminds You to Get Your Annual Fluoroscopy Exam
A plain film of the skull showing Huntington's disease
A cervical spine film of The Phantom
Top Five Most Common Comic Book Writer Medical Errors -- see the section on Bad Radiology.
Delivering Bad News the Comic Book Way -- apparently X-rays are helpful for this.