Guidance on Milligray (mGy)

What is a "mGy"?

The "mGy" is a unit used to express radiation dose. It is a measure of the energy absorbed in the organ or tissue exposed to radiation.

How many mGy of exposure are in everyday life events?

Everyone is exposed to radiation in the course of everyday life. There is a natural "background" radiation (from, for example, cosmic rays) and on average this background radiation exposes a person's thyroid to about 1 mGy per year.

A single chest x-ray gives a thyroid dose to a person of about 0.07 mGy. One transcontinental round-trip flight gives a thyroid dose of about 0.05 mGy.