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Understand the Uses and Dangers of Radiation

Worksheet Overview

QUESTION 1 of 10

In 2006, a former Russian spy called Alexander Litvinenko was taken critically ill after drinking some tea at a local café. He was taken into hospital and died 2 days later sparking the UK to try and find out what had happened to him. A real-life spy thriller started to take place in the heart of London. There were some clues as to what had killed Litvinenko – all his hair had fallen out, and he had developed black spots on his skin, signs for one type of poisoning – radiation sickness. 
The UK police and MI5 quickly broke out the GM tubes and traced the radiation throughout London, tracking the killer’s rout as small flecks of radioactive material had fallen off during travel. They examined the tea and found that it contained 0.2g of Polonium – 210, a radioactive material that gives off alpha radiation and can sometimes still be found in smoke detectors. But if this was able to kill someone in only 2 days, is it safe to be using in your home? Surprisingly, the answer is yes – very safe! In this activity, we will be looking at the different devices that use radiation and how we can go about using it safely. 

 

 

1 – Smoke detectors

 

Smoke detectors now commonly use a source of radiation called Americium. It is an alpha emitter with quite a low activity. It works by creating a flow of electrons in the air powering it. When the smoke gets in the way, this flow of electron is stopped an the alarm goes off. 

Is it safe?

Yes. 
First of all, α can only travel up to 15cm in air – so unless you are very tall, the smoke detector on your ceiling will not expose you to radiation. 
Secondly, it only takes paper to stop α and the smoke detector is surrounded by thick layers of plastic.
Thirdly, α is only dangerous to you if you get it inside your body – so don’t eat your fire alarm.
Finally, is it safe to have a low emitter of radiation in your house that cannot cause you any harm, or no smoke detector? Think about the benefits of having a smoke detector vs the risk of the radiation – what would you prefer? 

 

2 – Measuring the thickness of metal sheets

β is used for measuring the thickness of metal sheets during their manufacture. It makes sure that the sheets don’t get too thick or too thin so they can be used for their intended purpose. There is a detector on one side of the metal and a source of radiation on the other. If the sheet gets too think, the count will go down and the rollers will get thinner. If the sheet is too thin, the count will go up and the rollers will have to get further apart. 

Is it safe?


Most of the time.
There are strict controls about how closely people can get to the radiation. It is shielded by thick metal and checked for leaks regularly and only trained people who wear radiation meters are allowed close to it. It’s not going to explode, but you don’t want to increase the risk of people being exposed to it more than they have to be. 


3 – Killing cancer

γ is used to destroy tumours in hard to reach places. That’s right, something that can cause cancer is also used to kill it. You sit in a machine and are pinned in place so that you cannot move. The machine then shoots gamma radiation at you from lots of different angles. This makes sure that the area around the tumour is kept healthy and the tumour has the largest dose of radiation. They are normally given 15 Grey of radiation (1 grey is enough to instantly kill a human) but it is targeted at the tumour only, and so only kills the tumour.

 

Is it safe?
No.
You are receiving 15 times the amount of radiation that can kill a person, of course it is not safe. You have a chance of getting other cancers from doing this procedure!
Why do we do it then? 
Because it is worth the low risk of maybe getting another cancer to kill the cancer that you currently have. This type of therapy is generally used as a last resort because of the risks that come with it, but it will give the patient extra years on their life. 
What do you think – do the benefits of the radiotherapy outweigh the risks? 

 

Lets now have a go at some questions about what we have looked at in this activity. 

Jim hears that smoke detectors give off radiation and he is scared that his smoke detector is going to hurt him. Using ideas of benefit and risk, discuss why Jim should not be afraid of his smoke detector (3 marks)

An X-ray works by delivering a dose of radiation to the patient. This radiation is then absorbed by the bones in the body leaving shadows on some x-ray paper allowing the doctors to see the bones inside the body. It is considered safe to have a limited number of x-rays in a year, but the doctors have to wear protective clothing when conducting the X-rays. Using ideas of benefit and risk, suggest why it is considered safe for a patient, but not safe for a doctor. (4 marks)

What type of radiation does radiotherapy use? 

α

β

γ

Why would someone who has cancer choose to have radiotherapy, even though it comes with the risk of developing different cancers? (1 mark).

Which of the three types of radiation is the most harmful inside the body? 

Α

Β

Γ

At the supermarket, you can buy fresh fruit that has been irradiated. Irradiation makes the fruit last longer as it kills bacteria on the fruit. Jessie is worried that this fruit will give her cancer. Using ideas of contamination and irradiation, explain why she is wrong (3 marks) 

What type of radiation do smoke detectors use? 

What type of radiation is used to measure the thickness of a material? 

When using Beta to measure the thickness of a material, some scientists find that their reading goes down. Do they need to make the material thinker or thinner to return the reading to normal? 

Thicker

Thinner

Explain how radiation can lead to cell death (3 marks)

  • Question 1

Jim hears that smoke detectors give off radiation and he is scared that his smoke detector is going to hurt him. Using ideas of benefit and risk, discuss why Jim should not be afraid of his smoke detector (3 marks)

CORRECT ANSWER
EDDIE SAYS
Okay, so for this question you needed to spot a few things before you attempted to answer the question, let's take a look at them in order. 1 - this question was worth three makes, that means that the examiner will be looking for 3 things in your answer - so make 3 points! 2 - The keyword Discuss. This has a specific meaning - 'talk around the topic'. So, they are expecting you to talk about the good and bad points and how they can be applied to this scenario. 3 - 'Benifists and risks'. If ever you see this in a question, then you always put 'Benefits outweigh risks' in the answer. 4 - This is a science exam, and they have specifically mentioned α, so they more than likely want you to talk about alpha radiation. the rest of this question is about remembering the stuff that was discussed int the introduction. Or you could work it out from the information that you know from when we looked at alpha radiation.
  • Question 2

An X-ray works by delivering a dose of radiation to the patient. This radiation is then absorbed by the bones in the body leaving shadows on some x-ray paper allowing the doctors to see the bones inside the body. It is considered safe to have a limited number of x-rays in a year, but the doctors have to wear protective clothing when conducting the X-rays. Using ideas of benefit and risk, suggest why it is considered safe for a patient, but not safe for a doctor. (4 marks)

CORRECT ANSWER
EDDIE SAYS
This is a classic question. they give you a load of information that hints at the answer, and then ask you a question that you feel like you can answer, but you're not sure. That will happen every time you see the word suggest. Suggest means 'You probably haven't been told this, but we're given you enough information to work it out'. So, for this question, you are expected to dig through the question and find that the doctors have to wear protective clothing and that a limited number of x-rays are safe. This tells us that the more x-rays you get the more likely it is that something is going to go wrong and we have to take steps to slow that process down in people who are exposed to a lot of x-rays. Did you get all of that? Read it through again with this in mind and see if you can spot the clues!
  • Question 3

What type of radiation does radiotherapy use? 

CORRECT ANSWER
γ
EDDIE SAYS
Radiotherapy is designed to be a high dose of radiation to kill cancerous cells in the body. They need to be able to penetrate the skin (so not alpha) and have a high chance of hitting the tumor (so not beta). This means that they need to be gamma in order to destroy the part of the body that they need to.
  • Question 4

Why would someone who has cancer choose to have radiotherapy, even though it comes with the risk of developing different cancers? (1 mark).

CORRECT ANSWER
EDDIE SAYS
This is a strange question, but there are questions that cannot be answered by science. We call these ethical questions, and they don't really have a correct or incorrect answer - the answer will depend on the person you are asking. It is not the role of science to give answers, but it can help. In this case, it helps by giving information like the risk of developing a secondary cancer is low and the radiotherapy will help in the short term. The decision is still down to the patient, however, and some chose not to have radiotherapy.
  • Question 5

Which of the three types of radiation is the most harmful inside the body? 

CORRECT ANSWER
Α
EDDIE SAYS
The most harmful inside the body is the one that is going to cause the most harm to in the shortest space. Α is this one because it is the most ionizing and therefore will cause the most damage to atoms in your cells. Outside the body, it is stopped by your skin, but inside the body, you don't have that protection anymore and it will reak havoc on your body.
  • Question 6

At the supermarket, you can buy fresh fruit that has been irradiated. Irradiation makes the fruit last longer as it kills bacteria on the fruit. Jessie is worried that this fruit will give her cancer. Using ideas of contamination and irradiation, explain why she is wrong (3 marks) 

CORRECT ANSWER
EDDIE SAYS
This is where things get interesting - things that have been exposed to radiation are not dangerous - otherwise, we would not use radiation to clean medical instruments. It is only things that are contaminated that are dangerous. The firefighters in Chernobyl where irradiated by the exposed reactor core, but their suits were also contaminated by the radioactive dust. This means that they had to get the suits off as soon as possible to stop them from being exposed to more radiation. Contamination is when it has radiation on it or it has become radioactive and irradiation is when something has been exposed to radiation.
  • Question 7

What type of radiation do smoke detectors use? 

CORRECT ANSWER
Alpha
EDDIE SAYS
Smoke detectors need to use a type of radiation that is going to be stoped by a thin layer of smoke. This means that they need to use Alpha, as beta and gamma would go straight though think smoke, not set off the alarm, not wake you up and you might burn. Nobody wants that.
  • Question 8

What type of radiation is used to measure the thickness of a material? 

CORRECT ANSWER
Beta
EDDIE SAYS
To measure the thickness of a material, you need to be able to have radiation that is able to go through some materials but be stoped if that material is too think. This rules of Alpha, which will be stopped by almost anything and Gamma which will not be stopped by anything. This leaves us with Beta - it will go through metals, but only thin metals.
  • Question 9

When using Beta to measure the thickness of a material, some scientists find that their reading goes down. Do they need to make the material thinker or thinner to return the reading to normal? 

CORRECT ANSWER
Thinner
EDDIE SAYS
If it is stopping all of the radiation then that means that the radiation cannot pass through the sheet. This means that they need to make it thinner to return the readings to normal.
  • Question 10

Explain how radiation can lead to cell death (3 marks)

CORRECT ANSWER
EDDIE SAYS
The key thing here is remembering to use the term ionizing to describe what the radiation can do to the atoms in the cell. The ionization stops the cell from doing its job in the correct way - this leads to the cell either dying because it can\'t replicate itself or killing itself off because it knows that there is something wrong with it.
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