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Veterinary Diagnostic Techniques > Radiation > Flashcards

Radiation Flashcards

1
Q

What is radiation?

A

Energy that moves from one place to another in a form described as waves or particles.

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2
Q

What are the 3 types of radiation and how are they made?

A

Alpha, Beta, Gamma.

Made of unstable atoms which convert into more stable forms during a process of radioactive decay.

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3
Q

What do alpha, beta, and gamma radiation penetrate through?

A

Alpha - paper
Beta - aluminium foil
Gamma - Lead

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4
Q

What are the 3 principles of radiation safety?

A

Justification - any activity involving radiation must be justified by a clear benefit that outweighs the risk.

Dose limitation - The dose of radiation should be kept as minimal as possible. Every step should be taken to minimise exposure to radiation such as use of shielding, limit exposure time, maintaining distance from radiation.

Optimisation of Protection - All practices involving radiation should be optimised to ensure that the risks are minimised. Includes using appropriate equipment, training personnel and following established procedures.

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5
Q

What is the purpose of the 3 principles of radiation safety?

A

Essential for protecting individuals and the environment from the harmful effects of radiation.

Provide a framework for decision-making in various industries.

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6
Q

What are the 4 properties of radiation that make them hazardous?

A

Invisible
Painless
Latent effects
Cumulative

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7
Q

What are the biological damages of radiation?

A

Somatic damage: direct changes in the body tissues.

Carcinogenic Damage: Induction of cancer in tissues.

Genetic Damage: Effects on the gonads.

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8
Q

What is the difference between Stochastic and Non-Stochastic adverse effects of radiology?

A

Stochastic - occurs by chance, relating to any dose rate.

Non-Stochastic - dose specific threshold, with a potential to lead to radiation burns.

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9
Q

What are somatic effects and the causes?

A

Direct changes in body tissues, can occur soon after exposure.
- skin reddening
- skin cracking
- blood disorders
- baldness
- digestive upset - dehydration
- cataracts

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10
Q

What are carcinogenic effects and the causes?

A

Induction of cancer in tissues that have been exposed to radiation.
Tumour develop in exposed tissues.

  • leukaemia
  • skin cancers
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11
Q

What are genetic effects?

A

When the gonads are exposed to radiation - i.e., the ovaries and testicles.

Leads to mutation within the chromosomes of the germ cells.
Can lead to inherited abnormalities with offspring.

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12
Q

What are 3 potential sources of hazardous x-rays?

A

Tube head
Primary beam
Secondary/Scattered radiation

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13
Q

What are the 3 types of x-ray machines?

A

Portable - commonly used in general and equine practices. Easy to transport. Output - 60mA.

Mobile - large and more powerful portable machines. Moved on wheels. Output - 100-500mA.

Fixed - most powerful, built into x-ray room, attached to floor. Output - 1250mA.

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14
Q

What are the principles of X-ray?

A

Produced when electricity from the mains is transformed into a high voltage current, with energy converting to X-rays.

Tiny packets of energy referred to as photons which travel in straight lines and can be focused into the primary beam.
Some photons can be absorbed or scattered, others can pass through the patient and reach photographic x-ray film or by a digital recording system.

An image is produced by computer manipulation of the data.

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15
Q

What are the 6 properties of X-rays?

A

X-rays are part of the electromagnetic spectrum which determines wavelength and frequency of radiation.

Energy is directly proportional to frequency and indirectly proportional to wavelength.

The frequency is the number of waves that pass a certain point in a specified amount of time.

The wavelength of a wave is the distance between any 2 corresponding points of adjacent waves.

X-rays and Gamma rays are very similar types of electromagnetic radiation.

High frequency and shortwave = HIGH energy.

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16
Q

What are the properties of atoms?

A

Protons: +ve charge, in the nucleus.

Neutrons: No charge, in the nucleus.

Electrons: -ve charge, orbit around the nucleus in planes.

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17
Q

How are X-rays produced?

A

X-ray photons are created when rapidly moving electrons are slowed down or stopped.
When travelling at high speeds they collide with other atoms and lose their kinetic energy.
Most of this energy is transformed into 99% heat and 1& x-ray energy.

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18
Q

What is the function of the tube head?

A

X-rays are produced in the tube head.
Responsible for a controlled x-ray beam.

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19
Q

How is an image formed?

A

Image is produced when exposure takes place and will appear, black, white and grey.

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20
Q

What is the ‘atomic number’ in relation to absorption during x-ray?

A

Bone has a higher atomic number than soft tissue which absorbs more x-ray photos and produces the paler areas of radiographs.

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21
Q

What is the ‘specific gravity’ in relation to absorption during x-ray?

A

Density or mass per unit volume:
Bone - high specific gravity
Gas - low specific gravity

AKA - thicker areas absorb more x-ray photons whereas thinner areas absorb less photons.

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22
Q

What do the different colours of the X-ray mean?

A

Very dark = gas
Dark grey = fat
Mild grey = soft tissue/fluid
Bone = nearly white
Metal = white

23
Q

How are exposures controlled?

A

Via Kilovoltage, Milliamperage/Milliamperage time, and Time.

24
Q

What is Milliamperage (mA)?

A

A current that measures the quantity of X-rays produced, controls the electrical current to the cathode and controls the heating of the filament.

25
Q

What happens when the Milliamperage is too low/high?

A

Too low - The radiograph will be pale.

Too high - The radiograph will be dark.

26
Q

What is Kilovoltage (kV)?

A

Energy that determines the speed and energy of which electrons hit the target (penetrating power).
Increasing the kV gives greater penetrating power.

27
Q

What happens if the kilovoltage is too low/high?

A

Too low - underexposed.

Too high - overexposed.

28
Q

What is Time (S)?

A

Controls the amount of time that a high voltage is applied for.

AKA - a longer time will produce more x-rays.

29
Q

What is Film Focal Distance (FFD)?

A

The distance between the focal spot and the x-ray film/cassette.
75cm is common in veterinary practice.

30
Q

What is the hazards of the primary beam and how are these helped?

A

High energy x-rays are produced.
For safety:
Light beam diaphragm - helps to visualise area of exposure.
Collimation - adjusts the area of exposure that should be no larger than the cassette.

31
Q

What is secondary/scattered radiation?

A

Produced in all directions when hitting a solid object.
Scatter is low energy/soft and is absorbed by protective clothing.

32
Q

How is Secondary/scatter radiation reduced?

A

Wear protective clothing.
Rotate staff taking part in X-ray.
Stay away from primary beam.
Use of lead backed cassettes and lead tabletops.
Collimating.

33
Q

What does ALARA stand for?

A

As low as reasonably achievable.

34
Q

What is ALARA?

A

A guiding principle in radiation safety.
Goal is to keep radiation exposure to people and the environment as low as possible whilst still achieving desired benefits.

35
Q

What are the 3 basic principles of ALARA?

A

Time: limit the amount of time near a radioactive principle.

Distance: increase the distance between yourself and the radiation source.

Shielding: put a barrier between you and the radiation source.

36
Q

How would you limit handler exposure to radiation? (4 points)

A

Never go under the primary beam, even in lead clothing.

Always use an LBD to collimate the beam if available.

Tabletop must be covered by lead to prevent the X-ray passing through the table to the handlers feet.

Stay 2m away from the beam when x-rays are in progress - out of the room where possible.

37
Q

How is a controlled area (x-ray room) known?

A

Must be labelled with the correct warning notices on the door - containing the radiation warning symbol and a simple legend.

When the x-ray machine is in use, a light source (usually red) above the door should be present on the outside of the room, warning not to enter.

38
Q

How is X-ray equipment kept safe? (5 points)

A

All machines serviced annually by a qualified engineer.

Leakage of radiation from the tube housing must not exceed certain level.

Beam filtration must be equivalent to at least 2.5mm aluminium.

Must be fitted with a collimation device, a light beam diaphragm.

Table should be lead lined (minimum 1mm thick) and larger than the maximum size of the beam.

39
Q

What should be included when recording exposures?

A

Bound book
Date
Patient identity and description
Which views have been taken
Exposure factors
Means of restraint
Quality of image
Depth of tissue
Personnel involved - especially if manually restrained (and what PPE was used)
X-ray lights - warning light function must be checked daily and recorded.

40
Q

What PPE should be worn?

A

Lead aprons
Gowns
Thyroid protectors
Gloves
Dosemeters

41
Q

What is a dosemeter?

A

A device used to monitor radiation in the x-ray room.
Should be worn on the trunk beneath the lead gown to monitor human exposure.

42
Q

What is a Film Badge Dosemeter?

A

Measures radiation exposure.
Contains a small piece of film which contains small metal filters which allow the assessment of the type of radiation to which the badge has been exposed.

Only worn by the person it is issued to.

Legal requirement for those working with radiation.

Normally used for 8-12 weeks.

43
Q

What is a Personal Electronic Dosemeter?

A

Assess an individuals exposure to ionising radiation in real time.

Can be expensive.

Can be used to monitor personnel that are infrequently involved in radiation work.

44
Q

What is a Thermoluminescent (TLD) Dosemeter?

A

Less commonly used.

Contains radiosensitive lithium fluoride crystals.

Can monitor patient and personnel.

TLD cards can be placed around rooms to ensure public isn’t exposed to more than 100 millirems a year from outside a building.

Needs to be sent away to be read.

45
Q

Who supplied Dosemeters?

A

National Radiological Protection Board.
UK Health Security Agency.

46
Q

What are the dose limits for employees or trainees over the age of 18?

A

Skin - 500mSv - 1cm squared

Extremities - 500mSv

Lens of the eye - 20mSv

47
Q

What are the dose limits for trainees under 18 years of age.

A

Skin - 150mSv

Extremeties - 150mSv

Lens of the eye - 15mSv

48
Q

What are the dose limits of any other person (members of public or employees under 18 years of age)?

A

Skin - 50mSv

Extremeties - 50mSv

Lens of the eye - 15mSv

49
Q

What positioning aids are available?

A

Sandbags
Ties
Foam wedges
Troughs/Cradles

50
Q

What is the use of sandbags for positioning?

A

Prevent movement of the patient.

They are radiopaque and will show up on x-ray.

Should not be present in the primary beam.

51
Q

What is the use of ties for positioning?

A

Used to prevent limb movement.

Can only be used on patients under a general anaesthetic.

52
Q

What is the use of foam wedges for positioning.

A

Used to prevent rotation.

Various shapes and sizes.

Radiolucent - can be within the primary beam.

53
Q

What is the use of troughs/cradles for positioning?

A

Used to prevent rotation.

Various sizes - depends on size of patient.

Radiopaque - cannot be within the primary beam.

Veterinary Diagnostic Techniques (17 decks)

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