Cathode rays and Roentgen ray

Roentgen ray and cathode rays are semantically related In some cases you can replace phrase "Roentgen ray" with "Cathode rays", this phrases are similar.

Roentgen ray noun - Electromagnetic radiation of short wavelength produced when high-speed electrons strike a solid target.

Cathode rays and roentgen ray are semantically related in picture of inside a body topic. You can use "Cathode rays" instead a noun phrase "Roentgen ray".