The other way of producing X-Ray is K-shell emission. The atoms of target material have their electrons arranged in closed shells of different energies and the K-shell is the lowest energy state of an atom. Tungsten target atom can give incoming electron enough energy to push electrons located on the shell of tungsten out of its energy state. Then, a tungsten electron of higher energy from an outer shell can fall into the K-shell. The energy lost by the falling electron shows up in an emitted x-ray photon. After that, higher energy electrons fall into the vacated energy state in the outer shell. K-shell emission produces higher intensity x-rays than Bremsstrahlung and the x-ray photon comes out at a single wavelength.
Peak kilovoltage(kVp), tube current (mA), exposure time (s) are significant factors for X-Ray production. Peak kilovoltage creates a potential difference between the cathod (source of the accelerated electrons) and the anod (Target Atom). Tube current determens the potential difference of the cathode`s terminals. Total energy delivered to tube is calculated according to the this formula;
Energy = kVp* mA* s = kVp* mAs
And the instantaneous power delivered to tube is calculated with the multipication of kVp and mA.
Power = kVp* mA
Anode characteristics also effect the efficiency and the kVp results of the X-Ray tube. Surface condition, composion, geometry are important factors. Aging of the anode surface can cause high probability of tungsten attanuetion to the patients. Also wrong chemical composions and the angle of the anode directly effects the final contrast of the X-Ray film.