Final answer:
A hyphen is used with 'X-ray' when it modifies a noun as in 'X-ray technician', serving as a compound-modifier. It is a verb when expressing the action of using X-rays, such as 'The doctor will X-ray the patient's arm'. It functions as an adjective when it describes something related to X-rays, for example, 'X-ray image'.
Step-by-step explanation:
The term X-ray should use a hyphen when it functions as a compound modifier before a noun, for instance, 'X-ray technician' or 'X-ray machine'. This is consistent with the general rule to use hyphens with modifiers that serve as a single idea to describe a noun. When used as a verb, 'X-ray' describes the action of applying X-ray technology, for example, 'The doctor will X-ray the patient's arm to check for a fracture.' The term acts as an adjective when it modifies a noun to denote something related to or involving X-rays, such as 'X-ray image' or 'X-ray procedure'.
It is important to understand the distinction between hyphenation for compound modifiers and the non-hyphenated use of terms. Terms like 'X-ray' do not require a hyphen when they do not immediately precede the noun they are modifying. For example, after a noun as in 'The images are X-rayed.'