The purpose of this study was to investigate the proportion of patients cur
rently being investigated by CT that could be investigated by MRI with a po
tential reduction in exposure to ionizing radiation. The health detriment a
rising from the radiation dose associated with CT has been quantified in te
rms of the number of likely cases of serious health effects. The results sh
ow that a significant saving in the collective radiation dose is possible,
with an associated detriment of between 0.23 and 0.33 cases of cancer or se
vere hereditary effects averted in one imaging department every year. In se
lecting the balance of provision of MRI and CT facilities, the health detri
ment associated with the radiation dose from CT should be considered.