4.3 Hazards and Uses of Radioactive Emissions and Background Radiation

Question 1

give 4 sources of background radiation.

Answer 1

1. rocks
2. cosmic rays from space
3. nuclear weapon testing
4. nuclear accidents

Question 2

what is the unit used to measure radiation dosage?

Answer 2

sieverts (Sv).

Question 2

how should background radiation be dealt with in calculations?

Answer 2

the background count should be subtracted from any readings before calculations (half lift etc.) are attempted.

Question 3

state two uses of nuclear radiation in the field of medicine.

Answer 3

1. examining of internal organs
2. controlling and destroying unwanted tissue

Question 3

why might the radiation dosage that different people experience differ?

Answer 3

• some occupations involve working with radiation
• background radiation differs with location due to things such as the locality of nuclear power stations or radiation related testing

Question 3

how many millisieverts equal 1 sievert?

Answer 3

1000 millisieverts = 1 sievert

Question 4

how is radiation used in sterilisation?

Answer 4

gamma emitters are used to kill bacteria/parasites on equipment.

Question 4

what factor determines how dangerous a particular radioactive isotope is?

Answer 4

the half-life of the isotope.

Question 4

why are isotopes with long half-lives particularly harmful?

Answer 4

• they remain radioactive for much longer periods of time
• they must be stored in specific ways to avoid humans and the environment from being exposed to radiation for too long

Question 5

explain the process of radiotherapy.

Answer 5

• gamma emitters direct gamma rays at the cancerous cells
• the cancerous cells absord the radiation and are killed

Question 6

how are medical tracers chosen?

Answer 6

they should have a short half life and decay into a stable isotope which can be excreted.
they should only release gamma radiation since it is weakly ionising and can easily pass through body tissue without damaging it.