Ionising Radiation

Learning Objectives• I must be able to recall when ionising

radiation is emitted.

• I should be able to describe the three types of ionising radiation.

• I might be able to explain the dangers of ionising radiation.

Infrared and Gamma Rays

• What are the similarities and differences between infrared and gamma rays?

The Incredible Hulk

What can make electromagnetic waves dangerous?

The higher the frequency.

The Higher the energy.

Ionising Radiation• What are the dangers of gamma rays?

• Gamma rays can cause mutations in DNA because they are a type of ionising radiation.

• But what is ionising radiation?

Ionising Radiation• Ionising radiation can remove

electrons from atoms to form ions.

Ions• Ions are chemically very reactive.

• If atoms in cells are ionised, the reactions that follow can damage DNA.

• Large amounts of exposure to gamma rays can kill cells! – How might this be useful?

How can gamma rays be used to treat cancer?

Radiotherapy is the use of high-energy ionizing radiation, such as gamma rays, to kill cancer cells.

The radiation dose may come from a radioactive source in a machine outside the body, which directs a beam of radiation at the cancer cells.

Steps to reduce the effects on healthy tissue include:splitting the radiation dose into a number of treatments; rotating the beam of radiation so that healthy cellsreceive a lower dose than the cancer cells.

Healthy cells can also be affected by the radiation applied to the body.

What are gamma rays?Gamma rays are emitted by certain radioactive materials and have many uses in medicine.

ultra-violetinfrared X-rays

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gammarays

wavelength of electromagnetic waves

Gamma rays are the highest-energy form of electromagnetic radiation and are beside X-rays in the electromagnetic spectrum.

Gamma rays have wavelengths between 0.001 and 0.1 nm (less than the size of an atom), which makes them the formof electromagnetic radiation with the shortest wavelengths.

Radioactive Elements• Some elements like radium, emit

gamma waves all the time and are said to be radioactive.

• Not all radioactive substances emit gamma waves, some emit particles called alpha particles or beta particles.

Alpha, Beta and Gamma• Alpha, Beta and Gamma are the

three types of ionising radiation and transfer energy.

• Alpha and Beta involve particles not waves

• But they can ionise atoms so are just as hazardous as gamma waves.