Ionising Radiation

Key Stage 3

Meaning

The hazard symbol for ionising radiation.

Ionising Radiation is radiation which can cause atoms to lose electrons and become ions.

About Ionising Radiation

Ionising radiation damages living organisms.

Ionising radiation may kill cells by damaging the parts inside them, particularly the DNA.

Ionising radiation can cause the appearance of burns to the skin. A high enough dose of Ionising Radiation can cause instant death.

Precautions

Safety Goggles - To reduce the chance of damage to the eyes.
Safety Gloves - To reduce the chance of getting any on the skin.
Tongs - To keep a distance from the radioactive source reducing the chance of damaging the skin.

Key Stage 4

Meaning

Ionising Radiation is radiation emitted from the nucleus of an atom which can cause other atoms to lose electrons and become ions.

About Ionising Radiation

The units of exposure to ionising radiation are the Sievert which is 1 Joule of energy from ionising radiation being absorbed by 1 kilogram of flesh.

In Nuclear Physics there are three types of ionising radiation:

Alpha Radiation - The emission of an alpha particle from the nucleus of an unstable isotope.
Beta Radiation - The emission of a beta particle from the nucleus of an unstable isotope.
Gamma Radiation - The emission of a gamma-ray from the nucleus of an unstable isotope.
Neutron Radiation - The emission of a neutron from the nucleus of an unstable isotope.

Ionising Atoms


When an alpha particle interacts with an atom the alpha particle can remove one or two electrons to ionise the atom.


When a Beta minus particle interacts with an atom the beta minus particle can pass on some of its kinetic energy to an electron in the outer shell causing the electron to escape ionising the atom.


When a gamma-ray interacts with an atom the gammarray is absorbed by an electron in the outer shell causing the electron to escape ionising the atom.

Neutron radiation is referred to as indirectly ionising because it does not affect the electrons orbiting an atom but it can cause the release of directly ionising radiation in two ways:

It can be absorbed by a nucleus making it unstable and causing it to release a gamma-ray.

It can decay into a proton and a beta particle releasing a gamma-ray

Comparison of Ionising Radiation

Radiation	Symbol	Relative Penetration Depth	Relative Ionising Potential	Extra Info
Alpha Radiation	α	Low	High	Alpha is the least dangerous outside the body as it cannot penetrate the skin, but the most dangerous inside the body because it is the most highly ionising.
Beta Radiation	β-	Medium	Medium	Beta is equally dangerous inside as outside the body as easily penetrates skin.
Gamma Radiation	\(\gamma\)	High	Low	Gamma easily penetrates the skin but mostly passes through the body without interacting with any atoms. However, at high intensities it is extremely dangerous.
Neutron Radiation	n	High	Indirect	Neutrons are the most dangerous to living tissue as it penetrates the skin easily and is likely to be captured by the nucleus of atoms inside the body making them radioactive.

Precautions

Safety Goggles - To reduce the chance of irradiation of the eyes.
Safety Gloves - To reduce the chance of contamination or irradiation of the skin.
Tongs - To keep a distance from the radioactive source reducing the chance of contamination or irradiation of the skin.
Point the radioactive source away from living organisms to reduce irradiation.
Store in a Lead container to reduce the irradiation of living organisms.

Ionising Radiation and Cancer

Exposure to ionising radiation is a risk factor in cancer because ionising radiation can cause DNA molecules to break. When the cell tries to repair the DNA it can make mistakes called mutations. If this mutation tells the cell to replicate constantly then this becomes cancer.

Medical Uses of Ionising Radiation

Ionising Radiation can be used for both medical imaging and irradiating tumors.

Radioactive Tracers

Radioactive tracers can be used to image specific glands, organs or trace the flow of fluids through organs.

Different glands and organs collect different compounds from the blood stream. A compound containing a radioactive isotope can be injected into the blood and this will accumulate in the desired gland or organ. While there the unstable isotopes decay and this can be detected. This can be used to create an image of that gland or organ.

Fluids in certain organs can become blocked. These blockages can be detected by injecting or ingesting a radioactive isotope which will accumulate at the blockage. This accumulation can then be detected as the unstable isotopes decays to produce ionising radiation.

Irradiating Tumours

The irradiation of tumours can be done using radioactive isotope.

Cancer cells are more sensitive to ionising radiation than healthy cells so they can be targeted by a stream of ionising radiation to kill those cells.

One method to irradiate tumours is to place a pellet of radioactive material into the centre of a tumour. This pellet is encased in a protective layer (to prevent contamination) of other tissues. Once the pellet has destroyed the cancer cells it can be removed.

Another method is to send multiple beams of ionising radiation from different directions so that they all cross over at the same point in the body (the location of the tumour). Where the beams cross over there will be a very high intensity of ionising radiation which will destroy the tumour.

Extra Information

References

Ionising Radiation

Contents

Key Stage 3

Meaning

About Ionising Radiation

Precautions

Key Stage 4

Meaning

About Ionising Radiation

Ionising Atoms

Comparison of Ionising Radiation

Precautions

Ionising Radiation and Cancer

Medical Uses of Ionising Radiation

Radioactive Tracers

Irradiating Tumours

Extra Information

References

AQA

Edexcel

OCR