Radioactivity and radioisotopes

• Applications of Radioactivity • Radioactive tracers

Beneficial uses of radioactivityControlled radioactivity can be used to (click on the picture for

more information):

Kill cancer cells

Sterilize food and medical equipment

Find leaks in pipesControl thickness in industry

Check organs work properly

Tracers in medicineThe patient drinks some iodine 131. A -probe measures the amount of radioactive iodine the thyroid gland takes in to check it works properly.

N.B.

All isotopes taken into the body should be GAMMA or BETA sources and never ALPHA.

Explain why…These tracers must have short half-life

Tracers in industryGamma emitter injected in the pipe

High radioactivity escaping from the crack

-ray detector Why don’t they use or ?

These tracers must have short half-life

Gamma source

Curing cancerHigh doses of gamma rays will kill all living cells

Gamma rays can be directed only at the cancer cells to cure the cancer

Sterilizing foodFor the same reason gamma rays can be used to kill the microbes in food and medical instruments.

UNSTERILIZED STERILIZED

Thickness control in industryIn paper mills, the thickness of the paper can be controlled by measuring how

much beta radiation passes through the paper to a Geiger counter. The counter controls the pressure of the rollers to give the correct thickness. With paper, or plastic, or aluminium foil, b rays are used, because a will not go through the paper.We choose a source with a long half-life so that it does not need to be replaced often.