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Science and Technology 1 > Practical Radiation Protection > Flashcards

Practical Radiation Protection Flashcards

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1
Q

What law does radiation follow?

A

The inverse square law

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2
Q

What are the 3 ways to reduce radiation exposure?

A

Limit time

Increase distance

Use shielding

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3
Q

What are the 2 types of fluoroscopy?

A

Fluoroscopy

Acquisition

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4
Q

How can we limit time to reduce radiation exposure?
(6)

A

If using fluoroscopy, limit exposure time (fluoroscopy uses moving x-rays)

Use pulsed exposure if possible

Reduce the pulse rate in fluoroscopy if lots of movement

If in nuclear medicine, spend less time around patients

If in nuclear medicine, patients have a yellow note to identify them

If you can leave the area, then leave it

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5
Q

What does last image hold mean in fluoroscopy?

A

The image is present even if the radiation isn’t being exposed to the patient anymore

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6
Q

If we double the distance from the source of radiation to us, what happens to the area over which the radiation is spread?

A

The area increases by a factor of 4

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7
Q

How does increasing the distance reduce radiation exposure?
(2)

A

The Rutherford we are from the source of radiation, the better

The effect increases as you increase the distance from the source

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8
Q

What are rules to follow in fluoroscopy?
(3)

A

Position the x-ray tube as far from the patient as possible

The x-ray tube must not be less than 30cm from the patient’s skin

Position the detector as close as possible to the patient, otherwise a higher dose of radiation will be received by the patient to get the same image

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9
Q

What is the half value layer of a material?

A

The thickness (amount) of a material that’s needed to reduce the dose by half

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10
Q

What does it mean if the half value layer of a material is thicker?

A

The material is less effective at reducing radiation

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11
Q

Do softer photons have more or less energy?

A

Less energy

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12
Q

Do harder photons have more or less energy?

A

More energy

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13
Q

Are softer photons more or less penetrating?

A

Less penetrating

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14
Q

Are harder photons more or less penetrating?

A

More penetrating

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15
Q

What’s the link between soft and hard photons and the penetration?

A

Th harder the photons are, the more penetrating they are

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16
Q

How much lead is added to shield us from radiation?

A

0.05mm

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17
Q

How does adding 0.05mm of lead shield us from radiation?
(2)

A

It reduces the number of photons, so the intensity in the beam decreases and the energy increases in the beam.

The softer lower energy photons are removed, so the beam contains harder and higher energy photons (beam hardening)

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18
Q

What is beam hardening?

A

When we remove the softer lower energy photons, causing the beam to move up to the harder end of the photon spectrum

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19
Q

When does lead ted to be used for shielding?

A

At lower energies

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20
Q

Why is a high atomic number used for shielding at lower energies?

A

Because it’s more attenuating for the photoelectric effect

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21
Q

What is used for shielding at lower energies?
(2)

A

Lead

High atomic number

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22
Q

What is used for shielding at higher energies?

A

Concrete

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23
Q

Why is concrete used for shielding at high energies?

A

Because it has a high density, which is more attenuating for the Compton effect

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24
Q

How does the half value layer work?
(4)

A

Low energy photons are removed when the material is present for the 1st half value layer

Now there’s only high energy photons so it’s harder to stop them. So the material needs to be thicker to stop it.

This keeps happening and the material keeps getting thicker

So the 2nd half value layer is more than the 1st half value layer

25
Q

Where is most of the scatter located around the x-ray tube?

A

It’s located towards the x-ray tube

26
Q

Why are the x-ray tubes under patients in fluoroscopy?

A

Because the scatter is towards the x-ray tube

27
Q

Since we know that the scatter is towards the x-ray tube in fluoroscopy, how can we protect ourselves from scatter?

A

Stand on the opposite side of the patient, away from the source

28
Q

What should we do if out hands end up in the primary beam during fluoroscopy?

A

It needs to be reported, so that the practice can be improved

29
Q

When can our hand only end up in the primary beam?

A

During safeguarding cases

30
Q

What does PPE stand for?

A

Personal
Protective
Equipment

31
Q

How much lead does PPE have?

A

0.2mm

32
Q

When is PPE mainly used?

A

In fluoroscopy

33
Q

When do we wear PPE?

A

As a last resort- to keep us safe

34
Q

What is the primary beam?
(2)

A

The x-ray between the detector and x-ray
Or
The x-ray between the patient and x-ray

35
Q

Will PPE protect us from the primary beam?

A

No

36
Q

Which is lower intensity- scatter or the primary beam?

A

Scatter

37
Q

When professionals, e.g. surgeons, have to put their hands in the primary beam, what is worn?

A

Lead gloves

38
Q

What is the issue with wearing lead gloves when needing to put hands in the primary beam?

A

The lead gloves cover the detector, so not all the x-rays are detected. So the detector increases the dose of radiation, causing more scatter and increasing the dose of radiation to the patient

39
Q

What is the most protective PPE equipment?
Why?

A

Ceiling mounted screens in fluoroscopy areas

Because they have 0.5mm of lead, but sometimes 2mm of lead

40
Q

Why have lead glasses been introduced?

A

Because radiologists began getting cataracts

41
Q

What does a thyroid shield do to the radiation?

A

It halves the dose of radiation

42
Q

When are rad pads used?

A

In cardiac cathatar

43
Q

What happens if we don’t position the rad pads properly?

A

The dose of radiation will increase for us and the patients

44
Q

What do rad pads do?

A

They protect the operator from scatter

45
Q

What should we do with ceiling mounted screens?
(4)

A

Use wherever possible

Challenge the clinician that we should use it

Place it as close to the individual to shield them as much as possible

If they’re multiple people and there’s not other ways of shielding them, the playing the screen closer to the patient may provide a larger shadow and protect them too. But it’ll be less effective for the operator

46
Q

What are the features of dosimeters?
(3)

A

They’re a form of PPE

They won’t protect us from the radiation- they only measure the amount of radiation that we’re exposed to

They’re treated as PPE, so we have a legal duty to use them and take care of them

47
Q

What parts of the body do dosimeters measure?
(3)

A

Whole body

Skin

Lens of eye

48
Q

What are the 2 types of dosimeters?

A

TL

OSL

49
Q

How do TL dosimeters work?

A

They emit light when heated

50
Q

How do OSL dosimeters work?

A

They emit light when stimulated by lasers

51
Q

What are the features of OSL dosimeters?
(3)

A

They’re small devices

They can be worn on fingers

They’re reusable

52
Q

What’s an example of digital readout dosemeters?

A

EPDs

53
Q

What are the features of digital readout dosemeters (EPDs)?
(3)

A

They read what your radiation dose is right now

They measure very low doses

They read background radiation too

54
Q

How should we wear dosimeters correctly?
(5)

A

Must be worn within the holder

Worn when in radiation areas

Label showing wearers name visible

Between hip and shoulder

Don’t wear it where it could be obscured (seen) by metal

55
Q

How should we store dosimeters correctly?
(5)

A

Keep away from hot pipes or radiators

Protect from chemical attack

Don’t store near luminous articles

Don’t pierce, bend or damage

Don’t take onto an aeroplane

56
Q

Where are dosimeters worn?
(3)

A

Collar- worn above PPE

Chest- worn below PPE

Waist- worn below PPE

57
Q

When should radiation safety be notified regarding dosimeters?
(5)

A

A dosimeter is lost

Doses are above investigation levels

A dosimeter is suspected to be damaged

If it’s dropped in a radiation area

If a staff member is involved in a radiation incident while wearing it

58
Q

Why does it benefit us to reduce the patient’s exposure?

A

Because the scatter we receive is related to the patient’s dose

Science and Technology 1 (17 decks)

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