The Japan earthquake and Tsunami has lead to critical incidents at nuclear power stations, and, understandably, concern over radiation levels throughout Japan. At the site of the incident, radiation levels soared to 400mSv per hour, but quickly fell to 0.6mSv per hour at the front gate of the plant hours later. Levels throughout Japan have been reported as 6uSv per hour this morning.

But what does these figures actually mean? And how do they relate to the doses of radiation we expose our patients to in clinical practice?

A CXR is about 0.02 mSv

Background radiation for a year in Dundee is 2.5 mSv

A helical CT scan of the Chest, Abdomen and Pelvis is about 12 mSv

Radiation sickness usually occurs at 1 Sv

Louis Slotin received 5.1 Sv during the criticality accident in 1946 that lead to his death

Radical radiotherapy is usually of the order of 50 Sv, in a number of fractions

If you want to learn more about the risks of ionising radiation associated with common radiological investigations, you can visit the Radiation Tutorial that Smithy devised last year.

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