Why is a medical X-ray not really an X-ray?

A medical X-ray is picture of your body taken by shooting X-ray photons through you. As the X-rays pass through your body, more of them are absorbed by your bones than by your organs and soft tissue, so when the X-rays reach the film, there is a weaker signal where they have passed through bone material, allowing the doctor to see a picture of your bones. Rather than referring to such a picture as "a picture taken by shooting X-rays...", the medical community has shortened it to "X-ray." When high energy astrophysicists refer to an X-ray, they are talking about an energetic form of light, not the film that your doctor looks at to diagnose your broken leg.