Radiation Dose

Key Stage 4

Meaning

Radiation dose is the energy absorbed by living tissue from a source of ionising radiation.

About Radiation Dose

The SI Unit of radiation dose is the Sievert (Sv).

Radiation dose is a scalar quantity as it has magnitude but does not have a direction.

The magnitude of a radiation dose is related to the harmful effects of ionising radiation. 1 sievert represents a 5.5% risk of causing cancer.

There are sources of ionising radiation everywhere and humans receive a radiation dose from this so called background radiation.

The level of background radiation a person is exposed to depends on a number of factors including their diet and where they spend their time living and working.

The yearly radiation dose of pilots is likely to be higher than average because at high altitude people are exposed to more cosmic rays.

The yearly radiation dose of miners is likely to be higher than average because many rocks are sources of ionising radiation.

The yearly radiation dose of hospital workers is likely to be higher than average because sources of ionising radiation are used in medical imaging.

The effects of a radiation dose range from the severe such as instant death due to a dose of several Sieverts at once through radiation sickness and cancer.

Radiation dose has a cumulative effect over a lifetime so for people in jobs which expose them to a higher dose is it important to limit their exposure as much as possible. This is done using protective clothing, barriers and limiting their time exposed to the ionising radiation.