What is the conversion between kV (X-Rays) and keV (Gamma)? Posted on April 18, 2018July 3, 2019 kV is actually the kilo Voltage at which an x-ray tube is operated. keV is the is the energy that an electron gains when it travels through a potential of one thousand volt. When an x-ray tube is operated at 50kV the electrons from the cathode are accelerated towards the anode and the electrons, on hitting the anode, produce the x-rays. The x-rays thus produced will have a spectrum of energies from a few keV to a maximum of 50keV. The average energy of the x-rays will be approximately one-third of the maximum energy 50 keV.