Using Radiation

Question 1

Give example uses of radioactivity

Answer 1

● Household fire alarms (smoke)
● Irradiating food
● Sterilisation of equipment
● Tracing and gauging thicknesses of materials
● Diagnosis and treatment of cancer

Question 2

How do smoke alarms work?

Answer 2

● Aradioactive substance is in the alarm which emits
alpha radiation
● The emitted alpha particle ionises the air in the detector
and causes a current to flow between the plates
● When smoke interferes with the radiation, the air is no
longer ionised and so no current can flow
● This reduction in current flow triggers the alarm

Question 3

State two uses of nuclear radiation in the field of

medicine

Answer 3

1. Examining of internal organs
2. Radiotherapy in the treatment of
   cancer

Question 4

What is the role of beta radiation in tracers?

Answer 4

● The tracer is inserted in your body, and targets
a specific part of the body
●The radioactive substance in the tracer
releases beta radiation which can be detected
by external machines

Question 5

How is beta radiation used to determine thickness?

Answer 5

● Abeta source is placed above the material and a
detector is placed below it
● If there is an increase in radiation detected by the
detector, too much radiation is passing through the
material, and so it is too thin
● If there is a decrease in radiation is detected, then the
material blocks too much radiation, and so it is too
thick

Question 6

Why is ionising radiation dangerous?

Answer 6

● It can damage tissue and kill cells

● It can cause cell mutations

Question 7

What is a consequence of cell mutation?

Answer 7

Cancer

Question 8

What precautions should people take when using

ionising radiation?

Answer 8

● Avoid handling the source directly (use tongs)
● Wear radiation protective clothing
● Keep the radiation in lead containers to reduce
the amount of radiation that can escape
● Keep exposure time to a minimum

Question 9

Does a long half life or a short half life make a

source more dangerous?

Answer 9

If it has a long half life then it would
remain highly radioactive for longer
therefore making it more dangerous

Question 10

What precautions are taken to reduce harm for

doctors and patients using ionising radiation?

Answer 10

● Only a small dose is given to the patient so they are not
exposed to too much.
● The radiation used has a short half life so it won’t remain
highly radioactive for long. This reduces the risk to the
doctors using it as well as the patient.
● Doctors and patients (when applicable) wear protective
clothing

Question 11

What is radioactive contamination?

Answer 11

The presence of unwanted radioactive

nuclei on other materials.

Question 12

What is irradiation?

Answer 12

● The process of exposing a material to
nuclear radiation
● The material does not become
radioactive

Question 13

How is a radioactive tracer used in medicine?

Answer 13

● The tracer is placed inside the body (it can be in a
drink, eaten or injected)
● The tracer releases gamma radiation which is
detected by a detector which moves around the
body
● This can then be used to produce a picture of the
patient’s body

Question 14

How does a PET scanner work?

Answer 14

● PET (positron emission tomography) uses a
tracer, which is injected into the patient’s body

Positron + electron= annihilation =gamma rays
● The scanner detects the gamma rays which
are released by the trace
● Multiple images are taken and this is used to
form a 3D image of the patient’s body

Question 15

Isotopes are used in PET scanners. What is

important about where they are produced and why?

Answer 15

They must be produced near the hospital
because the isotopes used have a short
half life so must be used soon after
production