Sources Of Radiation:
An Electron volt is an amount of energy equal to the energy. Gained by one electron when it is accelerated by one volt.
If one electron were accelerated by a potential of 100 Thousand volt ( 100 KV ). X-ray machine, The electron would have an energy of 100 thousand electrons volt/ 100 KeV.
When X- rays are produced, there is a wide range of energies ( wave Length ) Not all electrons are accelerated to the maximum voltage set on the X-ray machine.
However every gamma producing isotope emits rays of one or more specific energies.
Regardless of curies strength (Activity) or size of an isotope. The energy of individual rays remains the same