Uses of Radioisotopes

Question 1

What are radioisotopes?

Answer 1

Isotopes of elements that are radioactive

Question 2

What are the medical uses of radioisotopes?

3 uses

Answer 2

Gamma rays used to destroy cancerous tissue
Gamma radiation used to sterilise medical instruments
Iodine-131 which emits beta particles is used to measure the uptake of iodine by the thyroid gland

Question 3

How is gamma radiation used to destroy cancerous tissue?

Answer 3

A controlled dose of gamma radiation is used in radiotherapy to destroy cancer cells without damaging healthy tissue

Question 4

How is gamma radiation used to sterilise medical instruments?

Answer 4

Instruments are sealed in plastic bags and irradiated with gamma radiation which destroys all microorganisms resulting in sterile equipment

Question 5

How is iodine-131 which emits beta particles used the measure the uptake of iodine by the thyroid gland?
2 points

Answer 5

The patient ingests food containing iodine-131 which has a half-life of eight days
By measuring the amount of radioactivity in the thyroid gland doctors can tell how much of the iodine-131 has been taken up by the gland

Question 6

What is radiocarbon dating (carbon-14 dating)?

2 points

Answer 6

It is a technique used to determine the age of an object containing carbon.
It is based on the ratio of carbon-14 to carbon-12 in the object

Question 7

How are radioisotopes used in agricultural research?

3 points

Answer 7

Phosphorus-32 is used in ‘tracer studies’ when studying the uptake of fertiliser by a plant
A fertiliser containing phosphorus-32 is fed to a plant
By measuring the radioactivity of the leaves of the plant, scientists can find out how much of the fertiliser has reached them.

Question 8

How are radioisotopes used in food irradiation?

Answer 8

Food is irradiated with gamma rays to destroy microorganisms responsible for food spoilage and food poisoning

Question 9

How are radioisotopes used in smoke alarms?

2 points

Answer 9

Americum-241 emits alpha particles which allow a small current to flow into the smoke alarm
If smoke enters the alarm the alpha particles are absorbed and the current is reduced which causes the the alarm to sound

Question 10

How are radioisotopes used in industry?

2 points

Answer 10

Leaks in water pipes can be located without digging by adding a radioisotope at one end of the pipeline
The ground can then be rested for any leaking radioisotope using a Geiger-Muller counter

Question 11

List the three main uses of radioisotopes?

Answer 11

Medical uses 
Archaeological uses 
Agricultural Research 
Food Irradiation 
Smoke Alarms
Industrial Uses

Question 12

Explain how the carbon-14 isotope allows certain archaeological discoveries to be dated
3 points

Answer 12

Carbon-14 decays by beta radiation but is continuously replaced when an organism is alive
When an organism dies the amount of carbon-14 present decreases but the amount of carbon-12 remains the same
Therefore, by measuring the ratio of carbon-14 to carbon-12 in the remains of a material scientists can date an object.