Hard X-rays have low photon energies , while soft X-rays have higher energy .
Spelling of X-ray ( s ) in the English language includes the variants x-ray ( s ) , xray ( s ) , and X ray ( s ) .X-rays with high photon energies ( above 5–10 keV , below 0.2–0.1 nm wavelength ) are called hard X-rays , while those with lower energy are called soft X-rays .
X-ray