X and Gamma Rays

1
X and Gamma Rays

• ? is the symbol for gamma

2
Making a radiograph

• X-rays pass through soft tissue but are absorbed
  by bone and thick metal plates
• X-rays from an X-ray tube directed at the patient
• A lightproof cassette of photographic film is
  placed the other side of the patient
• X-rays from the tube pass through the patients
  body
• Film is developed, parts exposed to X-rays are
  darker than other parts
• Areas under bones got less radiation so appear
  lighter.

3
Using gamma rays

• gamma rays similar to X-rays but a shorter
  wavelength
• used to kill bacteria in food
• used to sterilise surgical instruments
• used to kill cancer cells

4
Gamma therapy

• narrow beam of gamma rays directed at a tumour
  from different directions
• kills the tumour cells but little of the
  surrounding tissue
• cobalt-60 is the source of the gamma rays, stored
  in a lead container

5
Safety

• high doses of X rays and gamma rays kill living
  cells
• low doses of X rays and gamma rays cause cell
  mutation and cancerous growth
• living cells will always be damaged, even if the
  dose is very low
• Workers using X or gamma radiation need to use
  film badges, protective screens etc.