Year 10 Science · Unit 2 · Lesson 25

Using Radioisotopes, Medicine, Industry and the Environment

Apply Worksheet

Name

Date

Class

Learning Goals

Identify the odd one out in groups of radioisotope applications and properties.
Apply reasoning to a real medical scenario using technetium-99m.
Connect isotope choice, radiation type, half-life, and safety in a structured response.

Warm Up

Odd one out

Circle the item that does not belong in each group. Then explain why it doesn't fit in the answer column.

#	Group	Odd one out + reason
1	Technetium-99m Cobalt-60 Iodine-131 Americium-241
2	Thickness gauge Gamma radiography Leak detection Cancer radiotherapy
3	Short half-life Gamma emitter Used as a tracer Stored for centuries
4	Sterile insect technique Fertiliser tracing Food irradiation Smoke detector
5	Shielding Distance Limiting time Long half-life

Your Turn

Application scenario: a bone scan

A patient is given an injection containing technetium-99m, ^99m₄₃Tc. This isotope emits gamma rays and has a half-life of about 6 hours. A gamma camera detects the rays leaving the body and builds an image, showing where the tracer has collected in the bones. The hospital orders fresh technetium-99m each morning because it cannot be stored for long.

Type of use Is this a diagnostic (imaging) use or a treatment use? Justify your answer.
Radiation type Why is a gamma emitter, rather than an alpha emitter, needed for this scan?
Half-life Explain why a short half-life of about 6 hours is an advantage for the patient.
Supply problem Use the half-life to explain why the hospital must order fresh technetium-99m each day.
Compare Cobalt-60 is used to treat cancer, not to scan. Explain why a long-lived gamma source suits treatment but not imaging.

Wrap Up

In one sentence, explain why the same property (the type of radiation given off) can be both useful and dangerous, using one example from this worksheet.