Last reviewed 01/2018
X-ray therapy is a type of external beam irradiation used in radiotherapy where only relatively low energy irradiation is needed - 40 to 140kV. The low energy means that adjacent structures can be easily shielded with a thin lead sheet.
X-rays are derived from braking energy - bremstrahlung, where the change of velocity of high speed electrons as they pass atoms results in the emission of a photon of electromagnetic radiation.
This radiation is usually used only in diagnostic circumstances - the intensity drops exponentially with depth, thus it is poor for deep tumours
It is reserved mostly for skin and surface lesions.