tomogram vs roentgenogram

tomogram and roentgenogram both are nouns.

Word	Noun	Adjective	Verb	Adverb
tomogram	Yes	No	No	No
roentgenogram	Yes	No	No	No

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

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

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

tomogram (noun)	roentgenogram (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