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M4 Radiology > Radiation Safety > Flashcards

Radiation Safety Flashcards

1
Q

Who was the first person to discover that radiation exposure had had adverse affects on the skin?

A

Dr Edmund Kells

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2
Q

What are the 2 types of biological effects of radiation?

A
  1. Deterministic (non-stochastic) - those we know will occur

2. Non-deterministic (stochastic) - those which may occur

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3
Q

When looking at DETERMINISTIC effects;

What happens with the biological effects below and above the threshold dose?

A

In deterministic effects;

Below threshold - the biological effects do NOT occur.

Above threshold - the biological effects DO occur.

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4
Q

Who can be damaged by deterministic effects?

In relation to the person affected, what are these effects known as?

A

All the damage effects the person exposed to the radiation.

It effects their body and therefore they are known as somatic effects.

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5
Q

Can somatic effects be positive and if so why?

A

Yes they can be positive.

This means you can determine the threshold dose and expose a patient to a specific dose of radiation for treatment (eg. kill of cancer cells that give rise to tumours)

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6
Q

Can deterministic effects be adverse?

A

Yes they can also be adverse

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7
Q

What are the two grades of biological deterministic effects of ionising radiation?

A
  1. Acute

2. Chronic

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8
Q

Give 2 examples of ACUTE deterministic effects of ionising radiation?

A
  1. Radiation sickness - If they receive 2-10 Sv whole body irradiation.
  2. Death - If they receive >10 Sv whole body irradiation
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9
Q

Give 4 examples of CHRONIC deterministic effects of ionising radiation?

A
  1. Hair loss
  2. Cataracts
  3. Sterility
  4. Obliterative endarteritis
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10
Q

When do deterministic effects occur?

A

They occur at random - chance or probability.

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11
Q

Is there a threshold dose associated with non-deterministic effects of ionising radiation?

A

No, there is no threshold dose.

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12
Q

Who can be damaged by non-deterministic effects of ionising radiation?

In relation to those affected, what are these 2 types of effects known as?

A

Can damage both the patient exposed to radiation and future children

These effects are known as somatic and genetic effects.

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13
Q

With non-deterministic effects;

Is the amount of damage related to the radiation dose?

A

No.

Although, there is less chance of damage if exposed to a low dose of radiation over a high dose.

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14
Q

With non-deterministic effects;

What do somatic effects often give rise to?

A

They often give rise to the development of malignancy

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15
Q

With non-deterministic effects;

What do genetic effects often give rise to?

A

Can give congenital abnormality which may include malignancy.

However, for these effects to occur the reproductive organs of either male or female would have to be exposed to radiation.

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16
Q

Out of deterministic and non-deterministic effects; which effects are most likely to occur in dentistry?

A

Non-deterministic effects

This can be problematic.

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17
Q

Why do non-deterministic effects occur more often than deterministic effects in dentistry?

A

As exposure is not sufficient enough for the radiation to reach a threshold dose that would cause deterministic effects.

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18
Q

List 3 factors that affect radiation dose?

A
  1. Type of radiation – we are interested only in x-rays
  2. Tissues being irradiated
  3. Age of the patient
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19
Q

Based on SEDENTEXCT, what is the typical effective dose for bitewings/periapicals ?

A

0.0003 – 0.022 mSv

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20
Q

What is the typical effective dose for DPT ?

A

0.0027 – 0.038 mSv

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21
Q

What is the typical effective dose for a maxillary occlusal ?
—

A

0.008 mSv

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22
Q

What is the typical effective dose for a Lateral Cephalometric ?

A

0.0022 – 0.0056 mSv

23
Q

What is the typical effective dose for a PA skull ?

A

0.02 mSv

24
Q

What is the typical effective dose for a —lateral skull?

A

0.016 mSv

25
Q

What is the typical effective dose for a Chest PA ?

A

0.014 mSv

26
Q

What is the typical effective dose for a dento-alveolar CBCT ?

A

0.01 – 0.67 mSv

27
Q

What is the typical effective dose for a craniofacial CBCT ?

A

0.03 – 1.1 mSv

28
Q

What is the typical effective dose for a CT mandible & maxilla ?

A

0.25 – 1.4 mSv

29
Q

Who does the dose limitation apply to ?

A

Applies to workers.

30
Q

What is the mean dose limit for dental workers ?

A

<0.1mSv

31
Q

What dose is recommended that should never exceed?

A

1mSv (dose limit for the public)

32
Q

What is the dose limits for patients?

A

There are no set dose limits for patients.

  • Although there are no limits, you must keep in mind the ALARP principle
33
Q

When should patients be exposed to radiation?

A

Only if it is clinically necessary, in order to diagnose and treatment plan their problems

34
Q

What does ALARP stand for?

A 
As
Low
As
Reasonably
Practicable
35
Q

What is the chance of dying from a periapical?

A

1:5,000,000

36
Q

What is the chance of dying from a DPT?

A

1:1,000,000

37
Q

Does age of the patient affect their risk of developing adverse affects from radiation?

A

Yes,

The younger the patient is = the GREATER the risk of developing adverse affects from radiation.

38
Q

What are the 4 different sources of ionising radiation?

A
  1. Natural background incl. food 84%
  2. Fallout & radioactive waste <1%
  3. Medical & Dental 15%
  4. Occupational <1%
39
Q

Which source emits the highest % of ionising radiation?

What is the % of radiation emitted by this source?

A

Natural background incl. food

84%

40
Q

Which sources emit the lowest % of ionising radiation?

What is the % of radiation emitted by these sources?

A
  • Fallout & radioactive waste
  • Occupational

<1%

41
Q

List 5 radioactive foods

A

Any 5 of these:

  • —Brazil nuts
  • —Butter beans
  • Bananas
  • Potatoes
  • —Carrots
  • —Red meat
  • Avocado
  • Beer
  • Water
  • Peanut butter
42
Q

What is the banana equivalent dose (BED)?

A

1 banana is equivalent to 1% of the average daily exposure

43
Q

What is the average daily exposure in BED?

A

100 BED

44
Q

What is a chest CT scan in BED?

What is this value in mSv?

A

70,000 BED

7mSv

45
Q

What must you consider before exposing a patient to radiation?

A

Consider:

The benefits of gaining the desired info in order to carry out diagnosis and treatment planning against

vs.

The potential harm of radiation dose to the patient (non-deterministic effects in dentistry which can occur at a low dose)

46
Q

What is Justification in Radiology?

A

Justification is the process in which we must undertake under current legislation, every time before exposing a patient to ionising radiation.

47
Q

List 3 ways that we can reduce dose?

A

Any 3 of these:

  1. Avoid unnecessary radiographs
  2. Use of Selection Criteria
  3. Film speed – use highest speed possible - preferably use F speed
  4. —Digital radiography may help - similar to f speed
  5. kV of machine – higher the kV, lower the dose
  6. —Rectangular collimation - much lower than round shaped beam
  7. Collimated DPT views - restricts radiation to areas of interest
  8. —Regular servicing of machines
  9. Knowledge & Understanding!
48
Q

What is beam intensity?

A

The number of “photons” in a beam at a specific place.

49
Q

What is inverse square law?

What does this mean?

A

Where the intensity of radiation is proportional to 1/the distance squared.

This means the further we are away from the source of radiation, the less likely we are to be exposed to many x-ray photons.

50
Q

What is the controlled area?

A

The area around the patient and the x ray tube, where only the patient should be present.

The rest of the controlled area is considered a ‘no go zone’.

51
Q

What is the size of the controlled area if the X-ray machines are working <70kv?

A

1.5m in diameter

It also extends in the primary beam for as long as it would take for the intensity of radiation to be almost minimum.

52
Q

What else is also important to have in your controlled area?

A

Protective barrier

53
Q

Where must the radiation activation button be found?

A

The button must also be behind this barrier.

54
Q

How far away should staff stand from all machines?

A

—DDHstand 2m away for all machines

M4 Radiology (12 decks)

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