Due to the hazard associated with ionising radiation, limits are placed on the dose of ionising radiation that the public may receive. These limits are:

External Sources
Category Radiation dose limit
(mSv per annum)
Members of general public 1
Radiation workers 20
Patients No Limit

Hence patients may legally receive any dose of radiation requested by medical practitioners. This places a significant responsibility on medical practitioners to make sure that they only use ionising radiation when it will be of benefit to the patient. Hence they need to be aware of the risks of radiation and to understand when diagnostic investigations using ionising radiation will be beneficial.