1. Combined Science (1-9): Radioactivity Uses and Dangers of Radiation

2. Objectives:

3. Uses and Dangers of Ionising Radiation
Draw a line under last lesson’s work and write today’s title in your book...
13/11/2018
c/w
Uses and Dangers of Ionising Radiation

4. FLASHBACK
FLASHBACK: Why are some telescopes situated on the Earth’s surface, and others need to be fixed to satellites [6 marks]

5. FLASHBACK- AFL
FLASHBACK: Why are some telescopes situated on the Earth’s surface, and others need to be fixed to satellites [6 marks]
There are many types of telescopes that detect different parts of the EM spectrum
Some parts of the EM spectrum are absorbed by the Earth’s atmosphere
Telescopes that detect these parts must be located on satellites for the waves to reach them
Others detect parts that are not absorbed and these can be situated on the Earth
Radio/Microwaves/visible as example of non-absorbed
UV/gamma/x-rays as example of absorbed

6. Uses
In groups suggest a real-life context use the ionisation and penetrance capabilities of alpha, beta and gamma radiation We will then go through the uses of each of the forms of ionising radiation separately

7. Put these in order, this will provide you with the information!
ALPHA: Smoke Alarms
Put these in order, this will provide you with the information!
If there is smoke in the way, the air is not ionised, so no current flows.
It ionises the air particles creating a current, that flows around the alarm circuit.
This sounds the alarm.
Alpha passes from the source to the detector.
Why would alpha radiation be the optimal choice to use in this context?
An alpha source is used because it is the most ionising, and because it can only travel a few cm in air so minimises risk to humans.

8. BETA: Thickness Checking
Draw the diagram opposite and then use what you know about the penetrance of beta radiation to determine how it is used to control the thickness of paper/foil
A beta source is placed on one side of the material, and a detector on the other.
The amount of radiation detected will change if the material become too thick or thin.
This is linked to a computer system which adjusts the rollers to change the thickness of the material accordingly.
A beta source must be used because……
If alpha it wouldn’t get through any paper and if gamma, it would be unaffected by any thickness of foil or paper

9. GAMMA (1): Environmental Tracers
Gamma can penetrate through the soil
Explain why using a gamma source in a gas pipe will help to indicate the source of leaks. Why must gamma be used and not alpha or beta?

10. GAMMA (2): Environmental Tracers
How might scanning radiation over food or medical instruments reduce the chances of sickness and infection?
Pieces of medical equipment are placed in a sealed bag and then exposed to gamma radiation.
When equipment is exposed to gamma radiation, any bacteria is killed.
This is also done for food, it travels through a gamma scan, killing off any bacteria!

11. Pain in their right side, under the diaphragm
A liquid containing a radioactive source is injected / swallowed by the patient.
It passes through their body, and collects around cancerous cells.
These areas of increased radioactivity are detected from the outside of the body.
A gamma source must be used so that can pass through the skin to be detected outside of the body.
As the leading general surgeon, a very special case has come to you. Patient X has been admitted to hospital for the following symptoms:
Nausea and Vomiting
Pain in their right side, under the diaphragm
Yellowing of the skin
What may possibly be the cause of these symptoms?

12. A liquid containing a radioactive source is injected / swallowed by the patient.
It passes through their body, and collects around cancerous cells.
These areas of increased radioactivity are detected from the outside of the body.
A gamma source must be used so that can pass through the skin to be detected outside of the body.
Your medical students who are shadowing you have been asked to come up with some possible causes. When the medical history and blood report come back, you ask them to reassess…what can be eliminated?
Record what can be eliminated and why
Possible Causes:
Skin inflammation
Allergy to medication
Gastric Ulcer
Skin Cancer
Liver Cancer
Diabetes
Name: John Doe
Date of Birth:
Height: 178cm Weight: 13st 1lb
Family History:
Family history of stomach ulcers and digestive carcinomas. Mother died of severe septicaemia following complications with a gastric biopsy.
Details:
Smoker- smokes 10 a day
Non-drinker- sober since the age of 22
Drugs- Aspirin and beta-blockers for heart fluctuation twice daily. No other medication
Sun exposure- low, works in an office
Factor
Normal Range
Patient Result
Glucose Levels
3.2
Red cell count
5-12 8
White cell count
3-9 12
Inflammatory factors
5.2
AFP- organ function
5.36

13. Pain in their right side, under the diaphragm
Nausea and Vomiting
Pain in their right side, under the diaphragm
Yellowing of the skin
A liquid containing a radioactive source is injected / swallowed by the patient.
It passes through their body, and collects around cancerous cells.
These areas of increased radioactivity are detected from the outside of the body.
A gamma source must be used so that can pass through the skin to be detected outside of the body.
You deduce that the patient has either a gastric ulcer or liver cancer…
What should the medical team do now?
You order a complete set of scans including an X-ray and a PET scan. You later receive these images…
What can you see?
PET
What is the likely cause of the symptoms?
XRAY

14. What shape is the tumour you need to remove? Are you sure of this?
The patient has a clear tumour in their liver, they also have metastases (spreading of cancer) in the stomach and kidneys.
You decide to operate. Your students think that this image is suitable to plan the removal of the liver tumour…why is this not necessarily true..
What shape is the tumour you need to remove? Are you sure of this?

15. A full 360 degree PET scan of the body reveals that the tumour is not just a round ball but has a second lobe to it!
How does this image now improve the chances of a successful cancer removal?
Thanks to your quick thinking, the patient makes a swift recovery after a course of chemo!

16. But what exactly is a PET scan and are they 100% safe?
A liquid containing a radioactive source is injected / swallowed by the patient. This is bound to a simple molecule that goes into every cell, such as glucose!
Tumours deal with glucose differently and so interact with the source. This causes it to emit positrons
When positrons in the tumours meet electrons of your cell’s atoms, they collide and turn into pure energy…GAMMA waves!

17. Is there a hidden risk though? Remember…this is still gamma radiation!
But what exactly is a PET scan and are they 100% safe?
When these waves are made, they come out perpendicular to the collision. This occurs in lots of different places in the tumour.
When the gamma is emitted, it passes out of the body and can be detected by cameras that are rotated around
This produces a 3D image of the tumour!
Is there a hidden risk though? Remember…this is still gamma radiation!

18. The BENEFITS of a PET scan definitely OUTWEIGH the RISKS
Although you are using this to detect cancer, there is still a possibility of causing it via ionisation due to gamma. That’s why you use a radiotracer with a short half life!
If it were to remain active in the body for too long, it could cause damage!
If you’re using a short half life tracer, where must the tracer be made?
The BENEFITS of a PET scan definitely OUTWEIGH the RISKS
Justify this statement

19. Gamma can also be used the opposite way, targeted AT cancers to kill the cells!
A narrow beam of gamma radiation is fired at the cancerous cells.
The angle of the beam is changed to limit the exposure of healthy cells to the radiation.
Gamma is used because it is penetrating and can be targeted more accurately.

20. 6 mark question!
Ionising radiation has many medical uses. Explain and compare medical uses for two forms of ionising radiation

21. 6 mark question!
Ionising radiation has many medical uses. Explain and compare medical uses for two forms of ionising radiation
Gamma radiation used in medical treatment of cancer cells
Used by aiming the ray directly at cancerous cells to kill them
Gamma can also be used in PET scans
PET scans make a 3d image of the tumour
X rays are used to take photographs of broken bones
Both can cause damage to DNA leading to cancer or healthy cell damage if used for extended periods
X-rays are a 2D image but PET scans are a 3D image