tomogram vs X-ray

tomogram and X-ray both are nouns.

Word	Noun	Adjective	Verb	Adverb
tomogram	Yes	No	No	No
X-ray	Yes	No	No	No

As nouns, X-ray is a hypernym of tomogram; that is, X-ray is a word with a broader meaning than tomogram:

tomogram: A tomogram is an X-ray image produced by tomography.
X-ray: a radiogram made by exposing photographic film to X rays; used in medical diagnosis

Other hypernyms of tomogram include roentgenogram, X-ray photograph, X-ray picture, X ray.

tomogram (noun)	X-ray (noun)
A tomogram is an X-ray image produced by tomography.	a radiogram made by exposing photographic film to X rays; used in medical diagnosis
	electromagnetic radiation of short wavelength produced when high-speed electrons strike a solid target