Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard X-rays are the higher energy, shorter wavelength X-rays. Soft x-rays or Grenz rays are less energetic and longer in wavelength. The short wavelength end of the X-ray spectrum overlaps the GAMMA RAYS wavelength range. The distinction between gamma rays and X-rays is based on their radiation source.

Descriptor ID	D014965
MeSH Number(s)	G01.358.500.505.970 G01.750.250.970 G01.750.750.918
Concept/Terms	X-Rays X-Rays X Rays X-Ray Xrays Xray X-Radiation X-Radiations Roentgen Rays Rays, Roentgen Radiation, X X Radiation Grenz Rays Grenz Rays Rays, Grenz

Below are MeSH descriptors whose meaning is more general than "X-Rays".

Below are MeSH descriptors whose meaning is related to "X-Rays".

Below are MeSH descriptors whose meaning is more specific than "X-Rays".