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Radiology Flashcards

1
Q

What does ionising radiation do?

A

Turns atoms into ions by knocking away electrons orbiting the nucleus

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2
Q

How much eV does each ionisation deposit?

A

35eV

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3
Q

What is are the direct effects of radiation on DNA?

A

Radiation interacts with the atoms of a DNA molecule or another important part of the cell

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4
Q

What are the indirect effects of radiation on DNA?

A

Radiation interacts with water in the cell producing free radicals which cause damage

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5
Q

What is the usual outcome for a single strand DNA damage?

A

Usually repaired

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6
Q

What is the usual outcome for double strand damage?

A

Sometimes repaired
May be faulty repair —> leads to mutations that affect cell function

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7
Q

What are the biological effects of radiation dependent on?

A

Type of radiation
Amount of radiation (dose)
Time over which the dose is recieved
Type of tissue/cell type irradiated

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8
Q

What is tissue radio sensitivity dependent on?

A

Function of the cells that make up tissues
If the cells are actively dividing (increased division = increased risk)

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9
Q

Which tissues are highly radiosensitive?

A

Bone marrow
Lymphoid tissue
Gastrointestinal glands
Gonads
Embryonic tissue

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10
Q

What tissues are moderately radiosensitive?

A

Skin
Vascular endothelium
Lungs
Lens of eye

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11
Q

What tissues are least radiosensitive?

A

Central nervous system
Bone and cartilage
Connective tissue

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12
Q

What are the three outcomes of DNA mutation?

A

Mutation repaired = viable cells
Cell death = unviable cells
Cell survives but is mutated = cancer

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13
Q

What is the absorbed dose?

A

Measurement of the energy deposited by radiation
Measures in Grays (Gy)

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14
Q

What is the equivalent dose?

A

Absorbed dose x weighting factor
Measured in Sieverts (Sv)

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15
Q

What is the equivalent dose of alpha?

A

20 Sv

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16
Q

What is the equivalent dose of beta, gamma and X-rays?

A

1 sV

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17
Q

What is the risk of cancer with a dose of 1mSv?

A

1 in 20,0000

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18
Q

What is the risk of cancer with an intra-oral x-ray?

A

1 in 10,000,000

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19
Q

What are the determinstic effects of radiation?

A

Tissue reactions (decreased bone marrow cells, cataract, sterility, hair loss)
Occur over certain (threshold) dose
Severity of effect related to dose

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20
Q

What are the stochastic effects of radiation?

A

The probability of occurence is related to dose received
Somatic: results in disease or disorder
Genetic: abnormalies in descendent

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21
Q

What are the effects of radiation during pregnancy?

A

Lethal potential with doses 100mGy before or immediately after after implantation of the embryo into uterine wall
During organogenesis >250mGy dose leads to growth retardation

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22
Q

What is the cancer risk in utero?

A

1 in 13,500 per 1mGy exposure

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23
Q

What is the effective dose of an intra-oral radiograph?

A

0.005mSv

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24
Q

What is the staff dose limit for body, skin and eyes?

A

Body: 20mSv
Skin/extremities: 500mSv
Eye: 20mSv

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25
Q

What is the minimum distance for staff from the X-ray machine?

A

1.5m

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26
Q

What percentage do circular collimators increase the dose by?

A

40%

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27
Q

What are the four factors of dose optimisation?

A

E speed or faster (film); fewer X-ray photons
KV range of 60-70kV
Fsd: >200mm
Rectangular collimation

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28
Q

What are the diagnostic reference levels in an adult for a digital sensor?

A

0.9mGy

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29
Q

What are the diagnostic reference levels in an adult for phosphor plates and film?

A

1.2mGy

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30
Q

What are the diagnostic reference levels in a child for a digital sensor?

A

0.6mGy

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31
Q

What are the diagnostic reference levels in a child with a phosphor plate and film?

A

0.7mGy

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32
Q

What are the two types of receptors?

A

Digital and Film

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33
Q

What are digital receptors made up of?

A

Phosphor plate
Solid state sensor

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34
Q

What are film receptors made of?

A

Direct action film
Indirect action film

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35
Q

How many shades of grey are in 8 bits?

A

256

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36
Q

What does DICOM stand for?

A

Digital Imaging and Communications in Medicine

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37
Q

What does PACs stand for?

A

Picture Archiving and Communication System

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38
Q

What are the two needs for radiographic localisation?

A

To determine location of a structure in relation to other structures
Only if clinical examination is insufficient to provide an answer

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39
Q

What are 5 clinical situations where radiographic localisation may be used?

A

Position of unerupted teeth
Location of roots/root canals
Relationship of pathological lesions
Trauma
Soft tissue swelling

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40
Q

What is required for radiographic localisation?

A

2 views required
Views should be at right angles in their projection geometry
Aid of opaque objects

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41
Q

What is the rule for parallax?

A

Same
Lingual
Opposite
Buccal

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42
Q

What is the definition of parallax?

A

An apparent change in the position of an object caused by a real change in the position of the observer

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43
Q

What are the uses of radiographs?

A

Diagnosis
Treatment planning
Monitoring

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44
Q

What is the difference between radiology and radiography?

A

Radiology is a specialty of medicine
Radiography is an imaging technique

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45
Q

What does ALARA stand for?

A

As Low As Reasonably Practitionable

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46
Q

What is the main risk of dental radiology?

A

Carcinogenesis

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47
Q

What does IRR 2017 stand for?

A

Ionising Radiation Regulations 2017

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48
Q

What does IR(ME)R stand for?

A

Ionising Radiation (Medical Exposure) Regulation

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49
Q

What are some examples of justifications for radiographs?

A

Caries detection
Investigating infection
Orthodontic planning

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50
Q

What are the principles for radiographic protection?

A

Justification
Optimisation
Dose Limitation

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51
Q

What is processing in radiology?

A

Conversion of a latent image to a permanent visible image
Either digitally or chemically

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52
Q

What is the kV of a dental machine?

A

60-70kV

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53
Q

What are the three interactions with matter?

A

No effect
Complete absorption
Absorption and scatter

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54
Q

What is the receptor size for an anterior periapical?

A

0

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55
Q

What is the receptor size for a posterior periapical?

A

2

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56
Q

What is the receptor size for a bitewing?

A

2

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57
Q

What is the receptor size for an occlusal?

A

4

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58
Q

What side of the receptor should face the X-ray beam?

A

Blank side

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59
Q

What can be used to orientate a bitewing?

A

Curve of Spee

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60
Q
A
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61
Q

What are the specific attenuation interactions?

A

Photoelectric effect: complete absorption
Compton effect: partial absorption and scattering

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62
Q

When does the photoelectric effect take place?

A

Occurs when the energy of the incoming photon is equal to or just greater than the binding energy of an inner shell electron

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63
Q

What does the photoelectric effect result in?

A

Prevents X-ray photons from reaching the receptor- leads to lighter area on radiograph

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64
Q

What is the formula for the probability of the photoelectric effect?

A

Pe= p x Z3 / E3
P= proportion to physical density
Z3= cubed atomic number
E3= photon energy cubed

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65
Q

What is E3 affected by?

A

KV

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66
Q

What is the Z3 of lead?

A

551,368

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67
Q

What is the dose of a Periapical or Bitewing?

A

5uSV

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68
Q

What is the dose of a maxillary occlusal radiograph?

A

8

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69
Q

What is the dose of a lat cephalogram?

A

3

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70
Q

When does the Compton effect occur?

A

Energy of proton is much greater than binding energy of the electron

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71
Q

What do recoil electrons do?

A

Ionise and cause potential damage to adjacent tissues

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72
Q

Which photons cause forward scatter?

A

Higher energy

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73
Q

Which photons cause back scatter?

A

Lower energy

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74
Q

What does forward scatter present as

A

Darkening or fogging

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75
Q

What factors are associated with the probability of the Compton effect?

A

Independent of Z
Weakly proportionate to photon energy
Proportionate to density of material

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76
Q

What is the effect of collimation?

A

Decreased irradiated surface area
Decreased volume of irradiated tissue
Decreased number of scattered photons in tissue
Decreased scattered photons interacting with receptor
Decreased loss of contrast on image

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77
Q

What is the effect of lowering the kV?

A

Lower x-ray tube potential difference (kV)
Overall lower photon energy produced
Increased photoelectric interaction
Increased contrast between tissues with different Z (good)
Increased absorbed dose (bad)

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78
Q

What is electomagnetic radiation?

A

Flow of energy created by simultaneously varying electrical and magnetic fields

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79
Q

What are the features of electromagnetic radiation?

A

No mass
No charge
Travels at speed of light
Can travel in a vacuum

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80
Q

What is frequency in regard to EM waves?

A

How many waves per unit time
Measured in Hertz

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81
Q

What is speed in regard to EM waves?

A

Speed= frequency x wavelength

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82
Q

What is eV?

A

Energy gained by one electron moving across a potential difference of one volt

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83
Q

What are x ray photon energies?

A

124eV-124keV

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84
Q

What is amps?

A

How much charge flows past a point per second

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85
Q

What is current?

A

Flow of electrical charge

86
Q

What is voltage?

A

Difference in electrical potential between two points in an electrical field
Synonymous with potential difference

87
Q

What is the annual background radiation dose?

A

2.2mSv

88
Q

How can dose be limited in radiology?

A

Rectangular collimation
High kVp
Digital/fast film screens

89
Q

What are the roles in taking radiographs?

A

Referrer
Operator
Practitioner
Employer

90
Q

What are the roles in taking radiographs?

A

Referrer
Operator
Practitioner
Employer

91
Q

What does the referrer do?

A

Requests exposure

92
Q

What does the operator do?

A

Take the radiograph

93
Q

What does the practitioner do?

A

Decides if the exposure is justified

94
Q

What is the focal trough?

A

Layer in patient containing structures of interest
Affected by distance, X-ray beam width

95
Q

How do ghost images present?

A

Opposite side of
Horizontally stretched
Higher

96
Q

How are X-rays produced?

A

Rapid deceleration of electrons fired at high speed and collide, releasing kinetic energy which is converted into EM radiation and heat

97
Q

How can Compton scatter be reduced?

A

Collimation
Lead foil lining packers

98
Q

How can absorbed dose be decreased?

A

Using higher energy electrons

99
Q

What are the benefits of digital radiographs?

A

Faster
Digital manipulation
No physical space

100
Q

What are the disadvantages of digital radiographs?

A

Poorer resolution
Takes up data

101
Q

What are lateral cephalograms for?

A

Standardised and reproducible true lateral views of the facial bones

102
Q

What does an intensifying screen result in?

A

Less photons
Reduced dose

103
Q

What are the stages of radiograph development?

A

Develop
Wash
Fix
Wash
Dry

104
Q

What are the requirements for localisation?

A

Stable reference point
Horizontal /vertical tube shift

105
Q

What is the angle of a panoramic radiograph?

A

8 degrees

106
Q

What are examples of common abnormalities that can be seen on a radiograph?

A

Caries
Periodontal diseases/lesions
Impacted teeth
Hypodontia
Skeletal relationships

107
Q

What are examples of uncommon abnormalities that can be seen on a radiograph?

A

Jaw lesions such as cysts and tumours
Supernumeraries
Foreign bodies

108
Q

What does the term jaw lesions describe?

A

Cysts
Benign neoplasms
Cancers
Developmental abnormalities
Reactive lesions
Genetic conditions

109
Q

What are the seven factors in lesion description?

A

Site
Size
Shape
Margins
Internal structure
Effect on adjacent anatomy
Number

110
Q

What factors should be considered when discussing the site of a radiographic lesion?

A

Where is it?
Is there a notable relationship to another structure?
What is its position relative to a particular structure?

111
Q

What factors should be considered when discussing the size of a radiographic lesion?

A

Measure (estimate) dimensions
Describe the boundaries

112
Q

What factors should be considered when discussing the shape of a radiographic lesion?

A

General: rounded, scalloped, irregular
Locularity: unilocular, pseudolocular, multilocular

113
Q

What descriptions should be considered when discussing the margins of a radiographic lesion?

A

Well defined and corticated
Well defined and non corticated
Poorly defined and blending into the adjacent normal anatomy
Poorly defined and ragged or moth eaten

114
Q

What does a corticated lesion suggest?

A

Benign lesion

115
Q

What does a moth eaten lesion suggest?

A

Malignancy

116
Q

What descriptions should be considered when discussing the internal structure of a radiographic lesion?

A

Entirely radiolucent
Radiolucent with some radiopacity
Radiopaque (homogenous or heterogenous)

117
Q

What factors should be considered when discussing the internal structure of a radiographic lesion?

A

Amount- scant, multiple, dispersed
Bony septae; thin/coarse, prominent/faint, straight/curved
Particular structure: enamel and define radio density

118
Q

What can cause radiolucency in jaw lesions?

A

Resorption of bone
Decreased mineralisation of bone
Decreased thickness of bone
Replacement of bone with abnormal less mineralised tissue

119
Q

What can cause radiopacity in jaw lesions?

A

Increased thickness of bone
Osteosclerosis of bone
Presence of abnormal tissue
Mineralisation of normally non-mineralised tissues

120
Q

What factors should be considered when discussing the involvement of tooth of a radiographic lesion?

A

Around apex/apices
At side of root
Around crown
Around entire tooth

121
Q

What is the effect of jaw lesions on teeth?

A

Displacement/impaction
Resorption
Loss of lamina dura
Widening of pdl space
Hypercementosis

122
Q

What is the effect of jaw lesions on bone?

A

Displacement of cortices
Perforation of cortices
Sclerosis of trabecular bone

123
Q

What is the effect of jaw lesions on the inferior alveolar canal/ maxillary sinus/nasal cavity?

A

Displacement
Erosion
Compression

124
Q

What factors should be considered when discussing the number of a radiographic lesion?

A

Single
Bilateral
Multiple

125
Q

What do multiple jaw lesions suggest?

A

Syndrome

126
Q

What are the potential causes of a periapical radiolucency?

A

Periapical granuloma
Periapical abscess
Radicular cyst
Perio-endo lesion
Cemento-osseous dysplasia (in early stage)
Surgical defect (following peri-radicular surgery)
Fibrous healing defect (following resolution of lesion)
Ameloblastoma occurring next to tooth

127
Q

What features should be considered when facing a periapical radiolucency?

A

Clinical symptoms and signs
Condition of tooth, periodontal condition, treatment history
Patient demographic

128
Q

What can happen to infected cysts over time?

A

Can lose their well-defined, corticated margins
Can mimic radiographic features of malignancy
Check for signs of secondary infection- pain, swelling, purulent exudate

129
Q

What are some examples of not uncommon radiopacities?

A

Idiopathic osteosclerosis
Sclerosis osteitis
Hypercementosis
Buried retained roots

130
Q

What is idiopathic osteosclerosis?

A

Localised area of increased bone density of unknown cause
Asymptomatic

131
Q

Discuss the incidence of idiopathic osteosclerosis

A

6% population
Presents in adolescents
Commonly affects premolar region of mandible

132
Q

What is the radiographic presentation of idiopathic osteosclerosis?

A

Well defined radiopacity- often homogenous without radiolucent margin
Variable shapes- round, elliptical, irregular
Usually <2cm
Not associated/ not affecting teeth

133
Q

What is sclerosis osteitis?

A

Localised area of increased bone density in response to inflammation
May be symptomatic due to inflamamtion

134
Q

What is the radiographic presentation of sclerosis osteitis?

A

Well defined or poorly defined radiopacity
Variable shape
Associated with infective source

135
Q

How can we determine the difference between sclerosis and idiopathic osteosclerosis?

A

Look for signs/symptoms of infection

136
Q

What is hyper cementosis?

A

Excessive deposition of cementum around root- non-neoplastic and asymptomatic, tooth usually vital
Unknown cause
Can make extractions more difficult

137
Q

How does hypercementosis present on radiographs?

A

Single or multiple teeth involved
Homogenous radiopacity continuous with root surface
PDL space of tooth extends around periphery
Margins well defined and often smooth

138
Q

Where is the greatest biting force generated?

A

Between 1st molars- greatest root area

139
Q

What does the term clinical evaluation mean?

A

Covers the interpretation and documentation of any findings relevant to the patient’s management, treatment or prognosis
Covers the entire image
Must be recorded for every exposure and completed on the same day

140
Q

What is the difference between a clinical evaluation and a radiograph report?

A

A radiograph report is more comprehensive

141
Q
A
142
Q

What are skull radiographs primarily used for?

A

Maxilofacial trauma

143
Q

What types of maxilofacial trauma is not assessed using a skull radiograph?

A

Extensive/complex cases

144
Q

What are examples of skull radiographs?

A

Occipitomental
Postero-anterior mandible
Reverse towne’s
True lateral skull

145
Q

What is the main use of occipitomental radiographs?

A

Fractures of midface

146
Q

What is the main use of a postero-anterior mandible radiograph?

A

Fractures of the posterior mandible (except condyles)

147
Q

What is the main use of reverse towne’s radiograph?

A

Fractures of mandibular condyles

148
Q

What is the main use of reverse towne’s radiograph?

A

Fractures of mandibular conduces

149
Q

What is the x-ray machine like for skull radiographs?

A

Has a specialised skull unit
Patient positioned either standing up (erect) or lying on back (supine)

150
Q

What is the receptor like for skull radiographs?

A

Digital and larger enough to capture relevant areas

151
Q

What is the orbitomeatal line?

A

Reference line used in patient positioning for skull radiographs

152
Q

What is the orbitomeatal line also known as?

A

Canthomeatal line or radiographic baseline

153
Q

What are the landmarks for the orbitomeatal line?

A

Outer canthus of eye
Centre of external auditiory meatus

154
Q

What do occipitomental radiographs show?

A

Facial skeleton (avoiding superimposition of skull base)
Can be taken at different angles

155
Q

What are the indications for occipitomental radiographs?

A

Middle third fractures-
Le Fort I, II, III
Zygomatic complex (inc arch)
Naso-ethmoidal complex
Orbital blow out

Coronoid process fractures

156
Q

How is an occipitomental radiograph positioned?

A

Face towards receptor
Head tipped back so that orbitomeatal line is 45 degrees to receptor.

157
Q

Where should the X-ray Beam be positioned in a 0 degree OM?

A

Perpendicular to receptor and centred through occiput

158
Q

Where should the x-ray beam be positioned in a 30 degree occipitomental?

A

30 degrees above perpendicular line to receptor and centred through lower border of orbit

159
Q

Why is the postero-anterior radiograph not suitable for viewing facial skeleton?

A

Superimposition of base of skull and nasal bones

160
Q

What are the indications for a postero-anterior radiograph?

A

Lesions and fractures involving: posterior third of body, angles, rami, low condylar necks

Mandibular hypoplasia/hyperplasia

Maxilofacial deformities

161
Q

How is the patient positioned for an antero-postero radiograph?

A

Head tipped forward so that the orbitomeatal line is perpendicular to the receptor

162
Q

How is the X-ray beam positioned for a postero-antero radiograph?

A

Perpendicular to receptor and centred through cervical spine at the level of rami

163
Q

Why is the X-ray beam positioned posteriorly in a posterio-antero radiograph?

A

Reduces magnification of face (since close to receptor): less distortion of relevant structures, back of skull will be more magnified as a result but this is less important

Reduced effective dose: X-ray beam partly attenuated by back of skull before reaching face, lower radiation dose to radiosensitive tissues (lens of eye) as a result

164
Q

What does a reverse Townes radiograph show?

A

Condylar heads and necks

165
Q

What is the difference between an antero-postero and a reverse Townes?

A

Reverse Townes has a slightly different xray beam angle and the mouth is open

166
Q

What are the indications for a reverse Townes radiograph?

A

High fractures of condylar necks
Intracapsular fractures of TMJ
Condylar hypoplasia/hyperplasia

167
Q

What is the positioning for a reverse Townes radiograph?

A

Face towards the receptor
Head tipped forward so orbitomeatal line is perpendicular to receptor (forehead nose)
Mouth open

168
Q

Why is the mouth open during a reverse Townes radiograph?

A

Moves condylar heads out of glenoid fossa

169
Q

How is the xray beam positioned for a reverse Townes radiograph?

A

30 degrees below perpendicular line to receptor and centred through condyles

170
Q

What is cone beam computed tomography?

A

A form of cross-sectional imaging that is used to assess radiodense structures

171
Q

What are examples of non-DMFR used of CBCTs?

A

Temporal bone imaging
Paranasal sinus imaging
Orthopaedic imaging
Radiotherapy planning

172
Q

What are the basic principles of CBCT?

A

Ionising radiation:
Conical/pyramidal x-ray beam and square digital receptor rotate around the head

173
Q

What is the maximum beam rotations for a CBCT scan?

A

1

174
Q

How does a CBCT scan work?

A

Captures many 2 dimensional images which are reconstructed into a cylindrical 3D image

175
Q

What are the examples of unit types for CBCT?

A

CBCT only
CBCT + panoramic +/- ceph

176
Q

What is the patient positioning for CBCT?

A

Sitting or standing (depending on unit)
Rarely supine

177
Q

What is the head positioning for CBCT?

A

Same as panoramic:
Horizontal: Frankfort plane
Vertical: midsaggital line

178
Q

What are the benefits of CBCT over plain radiography?

A

No superimposition
Ability to view subject from any angle
No magnification/distortion
Allows for volumetric (3D) reconstruction

179
Q

What are the downside of CBCT over plain radiography?

A

Increased radiation dose to patient
Lower spatial resolution
Susceptible to artefacts
Equipment more expensive (initial, running and maintainance)
Images more complicated to manipulate and interpret
Requires additional training (to justify, operate and interpret)

180
Q

What are the main benefits of CBCT in comparison to conventional CT?

A

Lower radiation dose
Potential for ‘sharper’ images
Cheaper (initial, running and maintenance costs)
Smaller footprint

181
Q

What are the main benefits of conventional CT opposed to CBCT?

A

Able to differentiate soft tissues better
Cleaner images (better signal to nose radio)
Larger field of view possible

182
Q

What are the common uses of CBCT in dentistry?

A

Clarifying relationship between impacted mandibular third molar and inferior alveolar canal prior to intervention (after a plain RG has suggested a possible close relationship)

Measuring alveolar bone dimensions to help plan implant placement

Visualising complex root canal morphology to aid endodontic treatment

Investigating external root resorption next to impacted teeth (if not clear on plain RG)

Assessing large cystic jaw lesions and their involvement of important anatomical structures

183
Q

What are the common orthogonal planes?

A

Axial
Sagittal
Coronal

184
Q

What are the uses of 3D volume reconstruction?

A

May help clinician to picture the extent/shape of disease
Can be an informative teaching aid for the patient

185
Q

What are the drawbacks of 3D volume reconstruction?

A

It is a modified reconstruction of the data and so can create misleading images

186
Q

When should imaging factors/variables be set for CBCT?

A

Before the scan starts
Should be considered case-by-case using ALARP

187
Q

What are examples imaging factors/variables?

A

Field of view
Voxel size
Acquisition time (e.g. 10 seconds)

188
Q

What is the field of view?

A

The size of the captured volume of data

189
Q

What does an increased field of view lead to?

A

Increased radiation dose
Increased number of tissues irradiated
Increased scatter

190
Q

What is voxel size?

A

The image resolution

191
Q

What are voxels?

A

3D pixels

192
Q

What is the comparison between CBCT and radiograph pixels?

A

IO radiograph pixels are smaller

193
Q

What does decreased voxel size lead to?

A

(Indirectly) leads to increased radiation dose
Increased scan time

194
Q

What is the typical range of options for voxel size in CBCT scans?

A

0.4mm3-0.085mm3

195
Q

What imaging factors suit an endodontic case?

A

FOV as small as possible, unless there is large apical pathology
Small voxel size

196
Q

What imaging factors suit an implant case?

A

FOV depends on number/position of implants
Larger voxel size

197
Q

What does the radiation dose depend on in CBCT?

A

Equipment
Size of FOV
Position of FOV
Voxel size

198
Q

What is the approximate dose for a CBCT?

A

13-82 uSv

199
Q

What is the approximate effective dose for a CT?

A

474-1160 uSv

200
Q

What is the approximate effective dose for panoramic radiographs?

A

3-24 uSv

201
Q

What is the approximate dose for an intraoral radiograph?

A

4uSv

202
Q

What are artefacts?

A

Visualised structures on the scan that were not present in the object investigate

203
Q

What are the 2 main types of artefacts?

A

Movement artefacts
Streak artefacts

204
Q

When does a movement artefact occur?

A

If the patient is not completely still during the full exposure

205
Q

What are the features of a movement artefact?

A

Affects whole scan
Can lead to blurriness or extra contours
Typically reduced using fixation aids

206
Q

What are examples of fixation aids?

A

Chin rest
Head strap

207
Q

What are streak artefacts caused by?

A

High attenuation objects (metals)

208
Q

What are the main issues with streak artefacts?

A

Can prevent caries assessment adjacent to restorations
Can prevent assessment of perforations/missed canals in RCT teeth

209
Q

What are the contra-indications for CBCT?

A

If plain radiographs are sufficient

Pathology requiring soft tissue visualisation: malignancy, infection spreading in soft tissue

If high risk of debilitating artefacts

Patient factors; unable to stay still, unable to fit in machine

210
Q

Why may a patient be unable to stay still in the CBCT machine?

A

Parkinson’s disease
Learning difficulties
Uncooperative child

211
Q

Why may a patient be unable to fit in the CBCT machine?

A

Kyphotic patient (curving of the spine that causes bowling/rounding of back)
Unfavourable neck-shoulder ratio (obese, body builder)

212
Q

What is the justification for CBCT scan?

A

Must be preceded by a clinical exam
Only if plain radiography unable to provide sufficient information

Finals (20 decks)

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