Medical exposures relate to planned and deliberate exposure of a patient to Ionising Radiation for medical diagnosis or treatment. E.g. the use of X-Rays by dentists, CT Scans and incorporation of Sealed or Unsealed sources in the body. There are no 'Dose Limits' but there are usually recommended upper levels (e.g. diagnostic reference levels). The ICRP states that only necessary exposures should be made and these should be justified on the basis that the '..medical benefits of the exposure outweigh the radiation risk..' - i.e. a minimum dose that would be consistent with the medical benefit. The technology being medical exposures is advancing all the time. The use of collimated beams from advanced linear accelerators and proton beam irradiation is providing ever better cancer treatment.