1. Ionising Radiation

2. 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.

3. Infrared and Gamma Rays
What are the similarities and differences between infrared and gamma rays?

4. The Incredible Hulk

5. What can make electromagnetic waves dangerous?
The higher the frequency. The Higher the energy.

6. 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?

7. Ionising Radiation
Ionising radiation can remove electrons from atoms to form ions.

8. 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?

9. 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.
Healthy cells can also be affected by the radiation applied to the body.
Photo credit: Martin Dohrn/Science Photo Library
Gamma radiotherapy using a "cobalt bomb", radioactive cobalt-60 being the most common source of gamma radiation. The cobalt source is housed in the large treatment head, and gamma radiation is released through a shutter when the machine is in operation.
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 cells
receive a lower dose than the cancer cells.

10. What are gamma rays? ultra-violet gamma infrared X-rays rays
Gamma rays are emitted by certain radioactive materials and have many uses in medicine.
Gamma rays are the highest-energy form of electromagnetic radiation and are beside
X-rays in the electromagnetic spectrum.
ultra-violet
infrared
X-rays
10-3
10-9
10-6
10-12
gamma
rays
wavelength of electromagnetic waves
Gamma rays have wavelengths between and 0.1 nm (less than the size of an atom), which makes them the form
of electromagnetic radiation with the shortest wavelengths.

11. 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.

12. 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.