Radioactivity And Ionising Radiation

Question 1

What is a proton

Answer 1

Realtime mass 1

Charge +1

Question 2

What is a neutron

Answer 2

Mass 1

Charge 0

Question 3

What is an electron

Answer 3

Mass 1/2000

Charge -1

Question 4

What is alpha

Answer 4

A helium nucleus
Slow and heavy
Strongly ionising
Stopped by paper and skin

Question 5

What is beta

Answer 5

An electron
Light and fast
Moderately ionising
Stopped by thin metals

Question 6

What is gamma

Answer 6

Electromagnetic wave
No mass very fast
Weakly ionising
Stopped by thick lead or very thick concrete

Question 7

What is a positron

Answer 7

It is an anti particle of an electron
Relative mass 1/2000
Charge +1
They have the same properties as an electron
If they meet an electron they are annihilated

Question 8

What is neutron radiation

Answer 8

They are more penetrating than alpha beta or gamma
They’re not directly ionising but can be absorbed by nuclei of atoms in substances they pass through
Absorbing a neutron can make a nucleus radioactive
Neutrons are absorbed best by light nuclei such as hydrogen
Often neutron absorption makes nuclei emit gamma radiation

Question 9

What makes a nucleus unstable

Answer 9

Too many neutrons
Too few neutrons
Too many protons and neutrons together
Too much energy

Question 10

What does the curve of stability show

Answer 10

Any isotope not on the curve is unstable
An isotope above the curve has too many neutrons to be stable
An isotope below the curve as too few neutrons to be stable

Question 11

When does beta- decay happen

Answer 11

When there are too many neutrons

Question 12

What happens in beta- decay

Answer 12

Emission of an electron from the nucleus
It happens when there’s more neutrons than protons so one of the neutrons is changed into a proton
The proton number is increased by one and the mass number stays the same

Question 13

When does beta+ decay happen

Answer 13

When there are too few neutrons

Question 14

What happens in beta+ decay

Answer 14

A positron is emitted from the nucleus
A proton gets changed into a neutron
So the proton number decreases by one and the mass number stays the same

Question 15

When does alpha decay happen

Answer 15

When there are navy atoms with a z value (number of protons) above 82 like uranium and radium

Question 16

What happens is alpha decay

Answer 16

A helium nucleus is emitted

The proton number decreases by two and the mass number decreases by four

Question 17

When does gamma radiation happen

Answer 17

After alpha or beta decay the nucleus has lots of energy

Question 18

What happens in gamma radiation

Answer 18

It always goes with alpha or beta decay there’s no change in the proton on mass number of the atom

Question 19

What are quarks

Answer 19

Small particles that make up protons and neutrons

Question 20

Describe an up quark

Answer 20

Charge 2/3

Mass 1/3

Question 21

Describe a down quark

Answer 21

Charge -1/3

Mass 1/3

Question 22

What is a proton made up of

Answer 22

Two up quarks and one down quark
The charge is 2/3+2/3+{-1/3} = 1
The mass is 1/3+1/3+1/3=1

Question 23

What is a neutron made up of

Answer 23

One up quark and two down quarks
Charge is 2/3 +{-1/3}+{-1/3}
Mass is 1/3+1/3+1/3

Question 24

What happens when a neutron is turned to a proton

Answer 24

A down quark turns into an up quark

The overall charge still has to be 0 so an electron is also produced

Question 25

What happens when a proton turns into a neutron

Answer 25

An up quark turns into a down quark and a positron is released

Question 26

How are radioactive isotopes used in tracers

Answer 26

The trader is injected into the the patient or swallowed and an external detector follows its process as it moves around the body
A computer uses these images to create and image of where the strongest radiation comes from
Only isotopes with beta and gamma are used because they can pass out of the body they also have short half lives to reduce the amount of radioactivity inside the patient

Question 27

How is iodine 131 used in tracers

Answer 27

It is absorbed into the thyroid gland it gives out radiation which can be detected to indicate if the thyroid gland is taking in iodine like it should

Question 28

What are pet scans used for

Answer 28

They show areas of damaged tissue in the heart by detecting areas of decreased blood flow
This can show coronary heart disease or damaged or dead heart muscle caused by heart attacks
They can record blood flow and activity in the brain to diagnose diseases like epilepsy
They can identify active cancer Tumors by showing metabolic activity in tissue cancer cells have a much higher metabolism than healthy cells because they grow fast

Question 29

How do pet scans work

Answer 29

Inject the patient with a substance used by the body e.g. Glucose containing a positron emitting radioactive isotope
Positrons meet electrons and annihilate emitting high energy gamma rays which are detected
The distribution of radioactivity matches up with metabolic activity this is because more of the radioactive substance is taken into the cells that have increased metabolism

Question 30

Why do hospitals have their own cyclotrons

Answer 30

The isotopes in pet scanning have short half lives so it’s important they’re made close to where they are used otherwise the isotopes could have to be transported over long distances and their activity could be low by the time they are used so they’re no longer useful

Question 31

How does ionisation effect cells

Answer 31

It can kill a cell completely or damage it so it can’t divide causing tissue damage
It can change the genetic material in a cell this can cause mutations or make the cell divide and grow uncontrollably this is what causes cancer

Question 32

How is exposure to radiation limited

Answer 32

The lowest possible doses of radiation is used and a short exposure time
The patients could wear lead shielding to protect areas not being treated
Intensity decreases with distance so the staff should stand well away from the source
Staff can wear lead aprons or lead lined clothing to stop the radiation
The radiation dose must be carefully monitored

Question 33

How is radiation used internally to treat tumours

Answer 33

Internal radiation therapy means a radioactive material is placed inside the body into or near the tumour this can be done by injections or implanting a small amount of a radioactive substance this gives a high dose of radiation to a small part of the body limiting damage to the normal tissue

Question 34

How are tumours treated externally

Answer 34

Using high energy x rays or gamma rays aimed at the tumour

The radiation is focused at one part of the body but can affect healthy cells

Question 35

What are the pros internal radiation therapy

Answer 35

It is shorter than using external radiation methods so reduces the amount of visits a patient has to take to hospital
It has few side effects apart from some discomfort from the implant

Question 36

What are the bad things about internal radiation

Answer 36

They can cause the person to emit radiation after the source is emitted so they may have to limit contact with people until it is removed
Where as external sources mean the radiation only lasts a few minutes and they’re not radioactive now

Question 37

What are the downsides of using radiation in treatment

Answer 37

Even if precautions are taken the radiation can still harm some healthy cells leading to side effects such as sickness hair loss and skin irritation
There are long term effects such as bowel damage or infertility
The person could develop a second cancer caused by the treatment of the first treatment
Some people may refuse treatment because of these risks

Question 38

Why do some people chose to ignore the risks of radiation therapy

Answer 38

It doesn’t always lead to a cure but can be used to reduce suffering this is known as palliative care
It increases their life expectancy even if one of the risks were to happen their life would still be longer

Question 39

What are the ethical arguments against testing radioactive techniques

Answer 39

The new techniques could have harmful side effects but doctors won’t know for certain what the side effects are until it is tested on humans
Lots of patients might want to get onto the medical trial but places are limited
When a trial seems to work how long should it be before it is offered to anyone else because of the long term effects

Question 40

How are treatments tested

Answer 40

First on cells then animals then humans