Diagnostic Imaging Flashcards

1
Q

Wavelength and frequency are __ proportional

A

Inversely

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2
Q

List 3 properties of x-rays

A
  1. Short wavelength
  2. High frequency
  3. High energy
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3
Q

Which materials can x-rays penetrate?

A

Materials that absorb or reflect visible light

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4
Q

How do x-rays cause direct tissue damage?

A

By direct interaction with DNA

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5
Q

How do x-rays cause indirect tissue damage?

A

By the ionization of water molecules leading the formation of radicals

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6
Q

Which tissues are more affected by x-rays?

List 3

A
  1. Bone marrow
  2. Epithelial cells of the GI tract
  3. Early stage embryonic cells
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7
Q

What are the 2 classes of biological effects of x-rays?

A
  1. Stochastic effects
  2. Deterministic effects
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8
Q

Define stochastic effects

Give one example

A

Effects that have a random probability of distribution, and cannot be predicted precisely

Cancer or genetic effects

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9
Q

Define deterministic effects

Give one example

A

Effects that happen because of certain known conditions

Erythema, hematopoietic damage or cataracts

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10
Q

What does ALARA stand for?

A

As low as reasonably achievable

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11
Q

What are the units for absorbed radiation?

A

Gray (Jkg-1)

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12
Q

What are the units for effective dose of radiation?

A

Sievert

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13
Q

Define radiation exposure

A

Amount of ionization per mass air

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14
Q

Define absorbed radiation

A

Amount of energy transferred by radiation per mass

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15
Q

Define effective dose

A

A measure of radiation and organ system damage in humans

I.e. doses that are NOT received as a patient

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16
Q

What is the annual dose limit of radiation for the public vs a professional?

A

Public: 1mSv
Professional: 20mSv

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17
Q

What are 3 exceptions for the UK Veterinary Radiation Protection Regulations?

I.e. when can you go in to manually restrain the patient?

A
  1. Critical illness in which sedating the animal is dangerous
  2. Specific radiographic technique is required
  3. Patient type (i.e., large animal)
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18
Q

List 6 methods of radiation protection

A
  1. Filtration of the x-ray tube
  2. Time
  3. Distance
  4. Sheilding
  5. Collimation
  6. Personnel monitoring
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19
Q

What is the inverse square law when relating to the distance of radiographic imaging?

A

If the distance from the primary source is doubled, the intensity will decrease by a factor of four

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20
Q

List 3 ways you can sheild yourself from radiation

A
  1. Lead gloves
  2. Lead aprons
  3. Lead thyroid collar
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21
Q

What is a collimator?

A

A light beam diaphragm (like a view finder)

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22
Q

What are 2 types of dosimeters?

A
  1. Film badge
  2. Thermoluminescent (TLD)
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23
Q

How are x-rays produced?

A

Through conversion of kinetic energy of accelerated electrons into electromagnetic radiation

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24
Q

What is the source of electrons in an x-ray?

A

A cathode

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25
Q

Define x-ray tube current

A

Number of electrons flowing per second from the filament to the target

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26
Q

What is the source of deceleration in radiography?

A

The anode

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27
Q

A high potential difference leads the to __ of the electrons in a vacuum towards the anode

A

Acceleration

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28
Q

What is the charge of an anode

A

Positive

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29
Q

What is the function of the actual focal spot of an anode

A

It reduces over heating

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30
Q

What is the function of the effective focal spot of an anode

A

Improves detail

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31
Q

Compare small and large filament size in x-ray production

A

Small: finer detail and concentrates heat
Large: reduced detail but can use higher exposures

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32
Q

An x-ray beam is __

A

Polychromatic

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33
Q

List 3 things that happen when you increase KVp

(i.e., what else does it increase)

A
  1. Increases electron velocity
  2. Increases number of x-ray photons
  3. Increases energy
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34
Q

List 2 things that happen when you increase mA

(i.e., what else increases)

A
  1. Increases filament heating and tube current
  2. Increases number of x-rays being produced
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35
Q

Define attenuation

A

Decrease in intensity of an x-ray beam as it passes through matter

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35
Q

Define transmission

A

When an x-ray passes through matter without interaction

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35
Q

Define scatter

A

When the photon changes direction

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36
Q

What creates the image in an x-ray?

I.e., the shadowgram

A

The attenuation of the x-ray beam by the different tissues in the patient

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37
Q

Describe the photoelectric effect

A

When the x-ray photon is completely absorbed, and a photoelectron is removed from the shell of the tissue atom (it is ionized)
This gives off some radiation, but not enough to leave the body so it is not a safety hazard

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38
Q

Describe the compton effect

A

When the x-ray photon ejects an electron from the outer shelll of the tissue atom and the photon is scattered
The scattered photon has a lower energy than the x-ray photon and this may fog the film or be a safety hazard (scatter radiation)

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39
Q

The photoelectric effect is seen with __ radiation, and the compton effect is seen with __ radiation

A

Photoelectric: low range (up to 30kVp)
Compton: high range

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40
Q

Which form of x-ray absorption provides the best image contrast?

A

Photoelectric

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41
Q

What are the purpose of grids?

Bonus: when would you use them?

A

To reduce scatter & improve radiographic contrast

When using high range radiation (producing the compton effect)

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42
Q

What do you need to change about your x-ray when using grids?

Think lighting

A

Increase exposure

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43
Q

What are the 3 types of radiography?

A
  1. Conventional
  2. Computed
  3. Digital
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44
Q

Define latent image

A

The image that reflects the pattern of the part being radiographed

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45
Q

What are the 3 steps in manual film processing?

A
  1. Developer
  2. Fixer
  3. Wash
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46
Q

When is it recommended to use a grid?

A

When body part thickness is greater than 10 cm

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47
Q

Why do you need to increase the exposure when using a grid?

Bonus: how much do you need to increase exposure by?

A

To compensate for the portion of the primary beam absorbed by the grid

Increase exposure by a factor of 2-3

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48
Q

List 3 advantages of using an intensifying screen

A
  1. Reduce personnel exposure
  2. Reduce patient exposure
  3. Increase image contrast
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49
Q

Where is the image captured in computed radiography?

I.e., what is in the x-ray cassette?

A

A cassette containing a phosphor storage layer (no film)

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50
Q

List 3 advantages of computed radiography

A
  1. Time efficient
  2. Lower radiation dose
  3. Cost effective
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51
Q

List 3 disadvantages of computed radiography

A
  1. Laser reader is sensitive to dust
  2. Maintenance
  3. Manual labour required
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52
Q

How is the image produced in computed radiography?

A
  1. Cassette is put into a laser film reader
  2. Laser beam stimulates phosphor crystals to release stored light energy
  3. Computer generates a digital image in DICOM format
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53
Q

List 3 advantages of digital radiography

A
  1. Quick
  2. Good quality
  3. Lower radiation dose
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54
Q

List 2 disadvantages of digital radiography

A
  1. More expensive
  2. Fragile
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55
Q

How is the image produced in digital radiography?

A

There is an imaging receptor plate containing many small detector elements that transform x-rays into an electrical signal

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56
Q

Explain the difference between direct and indirect digital radiography

A

Direct: x-ray photon hits a selenium plate and the charges are transmitted to a computer for image construction
Indirect: x-ray photon hits a flat panel that creates visible light, the light photon then stimulates a photocathode which transmits energy to a computer for image construction

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57
Q

Describe image stiching

Bonus: how big can an image get?

A

When an x-ray tube takes multiple radiographs and fuses images together

Image size up to 1.2m

58
Q

Describe the process of fluoroscopy

A

X-rays are directed into a cathode ray vacuum tube to produce an image

59
Q

What is an advantage of using dynamic digital radiography over fluoroscopy?

A

DDR produces higher image quality

60
Q

What is the main advantage of using computed or digital radiography over conventional radiography

A

Computed and digital radiography do not require film or development, and all images are viewable from computers

61
Q

What does DICOM stand for?

A

Digital Imagine & Communication in Medicine

62
Q

What does PACS stand for?

A

Picture Archiving & Communication System

63
Q

Where are computed and digital radiographs sent after they are developed?

A

To PACS

64
Q

List 3 things an x-ray can/will do when it interacts with matter

A
  1. Absorbed
  2. Scattered
  3. Transmitted
65
Q

The photoelectric effect (for x-ray absorbtion/scatter) depends on __

Think principles of image formation

A

The atomic number of the tissue atoms

66
Q

The compton effect (for x-ray absorption/scatter) depends on __

Think principles of image formation

A

The density of the tissue

67
Q

Define radiolucent

A

Appears dark on radiographs

68
Q

Define radiopaque

A

Appears light on radiographs

69
Q

How can you visualize a 3D structure in 2D images like radiographs?

A

By taking at least 2 radiographic views of a given area

70
Q

Define penumbra

A

The partially shaded outer region of the shadow cast by an opaque object

71
Q

Define summation

A

The superimposition of structures in different planes

Remember: resulting image is the summation of opacities

72
Q

What is a DMPLO radiographic view?

A

Dorsomedial-palmaro/plantarolateral oblique

72
Q

Explain border effacement

A

When two structures of the same radiopacity are in contact with each other (their margins cannot be identified)

73
Q

What is a DLPMO radiographic view?

A

Dorsolateral-palmaro/plantaromedial oblique

74
Q

Which side of the patient does the marker annotate?

A

The anatomical side (right maker notes right side of patient)

Means the patient left will always be the image right

75
Q

To which side do we always position the patients head?

A

To the left of the image

76
Q

What do the markers annotate when the patient is in lateral recumbancy?

A

The side the patient is laying on (right marker means right lateral recumbency)

77
Q

Increased motion means you need to __ exposure time

A

Decrease

78
Q

What does kV represent

A

Penetrating power

Kilovoltage

79
Q

What does mA represent

Hint: exposure, but not exposure

A

Number of x-ray photons

80
Q

List 5 signs you are looking for to identify abnormalities on an x-ray

Bonus: what are the names of these signs

A
  1. Size
  2. Shape
  3. Opacity
  4. Location
  5. Number

Rontgen signs

81
Q

List 2 methods for radiograph interpretation

A
  1. Systematic (logical approach)
  2. Pattern (intuitive approach)
82
Q

What are Mach lines?

A

Thin light and dark grey lines at square borders on radiographs

These are visual inaccuracies

83
Q

List the following order of increasing radiopacities:
Fat, mineral/bone, gas, metallic, soft tissue

A

Gas < fat < soft tissue < mineral/bone < metallic

84
Q

Describe the fluorescent effect when using an intensifying screen

A

When using a screen, 95% of the film exposure is from the light given off by the screen

85
Q

Define contrast

A

The degree of perceptible difference between two colour tones

86
Q

Define object contrast

A

The difference in radiographic gray tones between two structures

87
Q

Define film contrast

A

The ability of an x-ray film to produce a degree of image contrast

88
Q

List 2 things that will decrease an image contrast

Think about settings on an x-ray

A
  1. Under/over exposure
  2. High kVp
89
Q

What is kVp?

A

The potential difference applied to an x-ray tube (the penetrating power)

The kilovoltage peak or kilovoltage

90
Q

How can fat increase and decrease contrast?

I.e., in which situations would it do one or the other

A

Normal fat provides contrast by prevent silhouetting
An excess amount of fat decreases contrast because you need a high kVp for penetration (high kVp decreases contrast)

91
Q

Gas surrounding abdominal organs __ contrast

A

Increases

92
Q

Define contrast medium

A

A substance applied to a patient to enhance the natural contrast of the organ of interest

93
Q

What is a negative contrast medium?

Provide an example

A

A medium that does not absorb x-rays (is radiolucent)

Air, CO2

94
Q

What is the purpose of using a negative contrast medium

A

To outline hollow organ walls

95
Q

What is a positive contrast medium?

Provide an example

A

A medium that absorbs lots of x-rays (radiopaque)

Barium sulphate or iodinated compounds

96
Q

What is the purpose of using a positive contrast medium

A

To outline the internal surface of hollow organs, vessels & ducts

97
Q

List 2 ways barium sulfate can be used and why

A
  1. Orally (for an upper GI study)
  2. Rectally (for an enema study)
98
Q

List 1 advantage and 1 disadvantage of barium sulfate

A

Advantage: provides a mucoprotective coating of the GI tract
Disadvantage: can be aspirated

99
Q

What is the main difference between ionic and non-ionic contrast media?

Bonus: What is the difference in their osmolarities?

A

Ionic: dissociates into cations and anions
Non-ionic: do not dissociate

Ionic: hyperosmolar
Non-ionic: iso- or low osmolar

100
Q

How is iodinated contrast media excreted?

Where is it excreted if this organ fails?

A

Mostly by the kidneys (glomerular filtration)

Via biliary or GI tract

101
Q

What are 2 types of iodinated contrast media?

A
  1. Ionic
  2. Non-ionic
102
Q

List 3 abdominal applications for iodinated contrast media

A
  1. Positive contrast cystography
  2. Angiography
  3. Portography
103
Q

What is a double contrast study?

Where would it be used?

A

When positive and negative contrast media are used

Esophagus, stomach, colon, urinary bladder

104
Q

What is the advantage of a double contrast study?

A

It highlights the mucosal detail with positive contrast while providing a dark background with negative contrast

105
Q

What is myelography?

A

When contrast medium is injected into the subarachnoid space outlining the spinal cord

106
Q

What are 3 advantages of myelography?

A
  1. Relatively inexpensive
  2. No special equipment
  3. Localizes spinal cord lesions
107
Q

What are 3 disadvantages of myelography?

A
  1. Invasive
  2. Technically challenging
  3. May be non-diagnostic
108
Q

How is contrast medium used in computed tomography?

A

IV iodinated contrast media is used, usually following a survery scan

109
Q

How is contrast media in magnetic resonance tomography?

A

Gadolinium is used as a paramagnetic substance to enhance the magnetic properties of neighouring molecules and provide contrast

Iodine is not used

110
Q

How is contrast media used in ultrasound?

A

IV injection of contrast media (ex. agitated saline) to enhance blood flow, and ultrasound is produced by the reflection of sound off gas bubbles produced by this enhanced blood flow

111
Q

List 3 clinical applications of a contrast ultrasound

What are they good at looking for?

A
  1. Portosystemic shunt
  2. Perfusion imaging
  3. Echocardiography
112
Q

List 3 clinical applications of contrast magnetic resonance tomography

What are they good at looking for?

A
  1. Increased vascularity
  2. Leaky vessels
  3. Selective distruption of BBB
113
Q

List 3 applications of contrast computed tomography

What are they good at looking for?

A
  1. Neoplasia
  2. Inflammation
  3. Abscess & cyst
114
Q

What is nuclear scintigraphy?

How are the images formed?

A

A branch of nuclear medicine that allows us to image the extent of a disease based on cellular function and physiology

Images formed by the detection of gamma radiation

115
Q

List 5 uses of muscuoloskeletal imaging

What can it identify?

A
  1. Lameness
  2. Swelling
  3. Localised mass
  4. Known trauma
  5. Pain
116
Q

List 3 soft tissue changes you can identify on an x-ray

A
  1. Generalized or localized swelling
  2. Soft tissue masses
  3. Calcification of soft tissues
117
Q

List the 4 types of new bone formation

A
  1. Osteophytosis
  2. Enthesophytosis
  3. Periosteal reaction
  4. Hyperostosis
118
Q

Define osteophytosis

A

New bone at joint surfaces

119
Q

Define enthesophytosis

What can it indicate?

A

New bone formation related to ligament/tendon attachments

Indicates soft tissue disease

120
Q

Define periosteal reaction

What can it indicate?

A

New bone formation resulting from stimulation of periosteum

Can indicate the aggression of the disease

121
Q

Define hyperostosis

A

An excessive growth of bone

122
Q

List 2 examples of hyperostosis

A
  1. DISH (Diffuse Idiopathic Skeletal Hyperostosis)
  2. Craniomandibular osteopathy
123
Q

Define osteosclerosis

A

Increase in bone density without a change in shape

124
Q

List 2 diseases where you will see osteosclerosis

A
  1. Osteopetrosis
  2. Canine panosteitis/equine enostosis
125
Q

What is osteopetrosis?

A

Defective osteoclastic resportion with loss of medullary cavity

126
Q

Define osteopenia

A

A reduction in bone mineral density

127
Q

What are the 2 types of osteopenia?

A
  1. Metabolic
  2. Disuse
128
Q

Describe the mechanism of metabolic osteopenia

In which condition can this occur?

A

Excessive Ca resorption from bone to maintain blood Ca levels results in a reduction in density

Hyperparathyroidism

129
Q

What is Wolff’s law?

A

The bone of a healthy person or animal will adapt to the loads under which it is placed

130
Q

List 3 types of fractures

A
  1. Traumatic
  2. Pathological
  3. Fatigue (stress)
131
Q

How do you classify fractures?

List 6 ways

A
  1. Location
  2. Transverse, oblique or spiral
  3. Complete vs incomplete
  4. Simple, comminuted, segmental
  5. Open vs closed
  6. Displaced vs non-displaced
132
Q

List the 5 steps of fracture healing

A
  1. Haematoma formation
  2. Woven bone + cartilage
  3. Ossification of cartilage
  4. Lamellar bone
  5. Recontoured lamellar bone
133
Q

List 3 things you should look for to assess fracture healing

A
  1. Reduction
  2. Alignment
  3. Soft tissues
134
Q

Define osteomyelitis

A

Inflammation of bone with medulla

135
Q

Define osteitis

A

Inflammation of bone without medulla

136
Q

Which pathologies are generally seen in infectious osteomyelitis

A

Periosteal reaction and osteolysis

137
Q

List 5 things you can see on a radiograph to indicate joint disease

A
  1. Osteophytosis
  2. Alterations in the subchondral bone
  3. Altered joint space
  4. Subluxation/luxation
  5. Periarticular structures
138
Q

How can you distinguish between an aggressive vs non-aggressive osteolytic lesion?

List 3 ways

A
  1. Look at the zone of transition
  2. Look at the rate of progression
  3. Look at the associated periosteal reaction
139
Q

Describe how cysts/slow growing lesions can lead to bone atrophy

A

Cysts can exert chronic pressure on adjacent bone resulting in thinning and deviation of adjacent bone structures

140
Q

Define sequestrum

A

A small avascular bone fragment from a fracture

141
Q

What is the name for a new bone formed surrounding a fracture?

A

Involucrum

142
Q
A