Is X-ray a proper noun

Answer 1

No, the word x-ray is a common noun, a word for any x-ray of any kind.

A proper noun is the name of a person, place, thing, or a title; for example:

• "The Man With the X-Ray Eyes", 1963 movie with Ray Milland
• X Ray Drive, Gastonia, NC; X Ray Street, Bloomer, WI; or X-Ray Lane, Dallas, TX
• The 200mA Medical Diagnostic X-Ray Machine, manufactured by Taixing Suxing Co., Ltd.

Answer 2

Yes, x-ray is a noun, a singular, common, concrete noun for the unit and a picture taken by the unit.

The word x-ray is also a verb for the act of taking an x-ray.