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Radiology Flashcards

1
Q

What is the SLOB rule in radiology?

A

used in the parallax technique. Same lingual, opposite buccal. Used to locate position of tooth

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2
Q

What is the name of the UK legislation that requires a radiographic report to be recorded for every radiograph

A

IRMER; Ionising Radiation (Medical Exposures) Regulations 2017

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3
Q

What is cervical burnout on a radiograph and what causes it?

A

It is caused by the varying attenuation of the x-ray beam by the normal anatomy present.
The dentine in the crown is surrounded by enamel, and the dentine in the more apical parts of the root are surrounded by bone, but the dentine in the cervical region is surrounded by neither and so there is less attenuation of x-ray photons. This results in a radiolucent band around the neck of the tooth, and this band is more radiolucent at the mesial and distal aspects of the tooth because roots have a round cross section and are therefore narrower at the edges.

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4
Q

What is the main benefit of rectangular collimation and why is this important?

A

It reduces the radiation dose to the patient by around 30%
This is important as ionising radiation in dentistry carries a small risk of carciogenesis.

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5
Q

In radiology, outline the steps in the bisecting angle technique.

A

*Place image receptor as close to subject as possible.
*Estimate the angle between the long axis of the subject and receptor.
*Bisect this angle with an imaginary line
*Aim the x-ray beam perpindicular to this bisecting line

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6
Q

From the OPT what is your assessment of this patients development in relation to his chronological age (12 yo boy)

A

Delayed lower premolars. Lower 5s developing ahead of lower 4s. Would normally expect lower first premolars at 10-11 and second premolars at 11-12 years.

This may be happening because of crowding in the lower arch. Also, lower 5s appear to be larger than normal.

ULQ is delayed in comparrison to URQ. UL4 expected to have erupted by now. Upper first premolars tend to erupt around 10-11

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7
Q

What is the purpose of quality assurance in dental radiology?

A

To ensure consistently adequate diagnostic information, whilst radiation doses to patients (and other persons) as kept ALARP, taking into account the relevant requirements of IRMER17 and IRR17

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8
Q

What checks are required for digital image receptors?

A

* Formally checked every 3 months or sooner if issue suspected.

* Receptor; visible damage to casing, wiring. Ensure cleanliness

* Image uniformity; expose receptor to unattenuated x-ray beam and check if resulting image is uniform

* Image quality; take radiograph of test object and assess the resulting image against baseline

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9
Q

How can damage affect a phosphor plate?

A

Scratches will appear as white lines

Cracking will appear as a network of white lines

Delamination will appear as white areas around the edges

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10
Q

How can damage effect a solid state sensor?

A

White squares or straight lines

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11
Q

What constitutes a diagnostically acceptable radiograph?

A

No errors or minimal erros in either patient preparation, exposure, positioning, image (receptor) processing or image reconstruction and of sufficient image quality to answer the clinical question.

Digital no less than 95%

Film no less than 90%

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12
Q

What consittutes a radiograph being diagnostically unacceptable?

A

Errors in either patient preparation, exposure, positioning, image (receptor) processing or image recontruction which render the image diagnosically unacceptable

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13
Q

What are the requirements of a bitewing to be diagnostically acceptable?

A

* Show entire crowns of upper and lower teeth

* Include the distal aspect of the fore standing posterior tooth an the mesial aspect of the last standing tooth (may require more than one image)

* Every aproximal surface shown at least once without overlap (where possible)

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14
Q

What are the requirements of a PA radiograph to be diagnostically acceptable?

A

Shows entire root

Shows periapical bone

Shows crown

Must also have adequate contrast, sharpness and resolution as well as minimal distortion

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15
Q

Give 2 examples of each type of bone pathology for; developmental, inflammatory, neoplasm, metabolic

A

Developmental; tori, dysplasia

Inflammatory; dry socket, osteomyelitis

Neoplasm; osteoma, osteosarcoma

Metabolic; osteoperosis, ricketts, Pagets, Giant cell lesion

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16
Q

Give 4 differential diagnosis for multilocular radiolucency

A

* Ameloblastoma

* KCOT

* Giant cell lesion

* Odontogenic myxoma

* Cherubism

* Aneurysmal bone cyst

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17
Q

What is the reason for distorted anteriors in an OPT?

A

Pt was not in the focal trough

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18
Q

What is the reason for a blurry image in an OPT?

A

Patient moved during exposure

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19
Q

What is the reason for an OPT image being too wide?

A

Canine guide set in front of the canines

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20
Q

When taking an OPT how can positioning errors be limited?

A

Use guides; temple rest, chin rest, bite block, hand rest, guide lights

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21
Q

Give 3 characteristics of a ghost image

A

Appears higher than the true image

Shows on opposite side

Appears larger/wider

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22
Q

Give 3 ways to reduce patient dose

A

* Beam diameter no greater than 60mm at end of spacer

* Rectangular collimation 40x50mm

* Focal skin distance 20-30cm

* 60-70kV

* Fast film F

* Aluminium filtration

* Lead absorption

* Limit exposure

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23
Q

What is compton scatter vs photoelectric effect?

A

Compton fogs and decreases image quality due to the xray hitting outer electrons and losing direction and energy.

Photoelectric complete absorption giving a white image as xray doesnt reach film

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24
Q

Besides lead, what metal is used in the xray tube head?

A

Aluminium, tungsten, copper

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25
Q

Regarding IRR17 give 5 safety features advised

A

* Controlled area

* Warning sign for controlled area

* A sign that lights up to indicate when equipment is on

* Light and audible sound during exposure

*Exposure with continuous pressure only

* Exposure stops automatically

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26
Q

What is ALARP

A

As low as reasonably practicable. Minimises exposure and dose

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27
Q

How is ALARP achieved?

A

Rectangular collimation 40-50mm, FSD 20-30cm, Fastest film available F speed or digital, 60-70kV. Aluminium filtration. Beam diameter no greater than 60mm at end of spacer

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28
Q

What is a radiation protection supervisor?

A

Ensures regulations and training are followed

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29
Q

What is a radiation protection advisor?

A

Advises on risk, regulations, training, quality etc

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30
Q

Compare and contrast the paralleling technique and bisecting angle technique

A

Paralleling; no contact but object and receptor are parallel and beam perpendicular to receptor.

Bisecting angle; in contact but not parallel and beam perpendicular to receptor

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31
Q

Why should radiographs be reported?

A

Medico-legal

Best practice

IRMER17

Records

Audit

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32
Q

According to IRMER17 what is the role of the employer

A

legal person, safety, make sure equipment in line with IRR17, staff follow regulations

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33
Q

According to IRMER17 what is the role of the referrer?

A

Check patient demographics, clinically justify radiograph, be trained

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34
Q

According to IRMER17 what is the role of the practitioner

A

Justifies exposure, benefits vs risks, check no recent relevant radiographs

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35
Q

According to IRMER 17 what is the role of the operator

A

Check patient demographics, ALARP, takes exposure, processes and reports

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36
Q

Identify this structure

A

Maxillary sinus

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37
Q

Identify this

A

Pneumatized maxillary sinus. When the sinus extends into an old extraction site

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38
Q

Identify

A

Pterygomandibular fissure. The space between the posterior border of the maxilla and the lateral pterygoid plate

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39
Q

Identify this structure

A

Lateral pterygoid plate; thin bony extension of the spenoid bone

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40
Q

Identify

A

Hamulus; small bony spine extending downward below the lateral pterygoid plate

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41
Q

Identify

A

Glenoid fossa

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42
Q

Identify

A

Articular eminence

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43
Q

Identify

A

Zygomaticotemporal suture

44
Q

Identify

A

Zygomatic air cells

45
Q

Identify

A

Zygomatic process

46
Q

Identify

A

External auditory meatus

47
Q

Identify

A

Mastoid process

48
Q

Identify

A

Middle cranial fossa

49
Q

Identify

A

Orbit

50
Q

Identify

A

Infra orbital foramen

51
Q

Identify

A

Infra orbital canal

52
Q

Identify

A

Nasal cavity

53
Q

Identify

A

Nasal turbinates

54
Q

Identify

A

Incisive foramen

55
Q

Identify

A

Ghost image of hard palate

56
Q

Identify

A

Palatine torus (Hard palate appears thicker than normal)

57
Q

If a cyst is suspected, what would be the initial radiographic investigations taken?

A

Periapical.

OPT

Occlusal

Supplemental include

CBCT

PA mandible

Occipitomental view

58
Q

How should the radiographic features of a cyst be described?

A

Location

Shape (often spherical or egg shaped, most grow by hydrostatic pressure)

Margins (often well defined, often corticated)

Locularity (unilocular, multi, pseudo)

Multiplicity (single, bilateral, multiple, multiple may indicate a syndrome)

59
Q

General overview of odontogenic cysts

A

Occur in tooth bearing areas.

Most common cause of body swelling in the jaws.

Account for 90% of all cysts in the oral and maxillofacial region.

All lined with epithelium

60
Q

What are the three odontogenic sources of epithelium?

A

Rests of malassez - remnants of hertwigs epithelial root sheath

Rests of Serres - remnants of the dental lamina

Reduced enamel epithelium - remnants of the enamel organ

61
Q

What is a radicular cyst and what is its clinical presentation?

A

Inflammatory odontogenic cyst.

Always associated with a non vital tooth

Initiated by chronic inflammation at apex of tooth due to pulpal necrosis

Incidence; more common in 4th and 5th decades, affects males and females equallly, 60% occur in maxilla, can involve any tooth

Often asymptomatic unless infected.

Typically slow growing with limited expansion

62
Q

What are the radiographic features of a radicular cyst?

A

Well defined round/oval radiolucency

Corticated margin continuous with lamina dura of non vital tooth

Larger lesions may displace adjacent structures.

Long standing lesions may cause external root resorption and/or contain dystropic calcificaiton

63
Q

What are residule and lateral cysts?

A

A residule cyst is when a radicular cyst persists after loss of tooth (of after successful RCT) Clinical history important to avoid mis diagnosis.

A lateral radicular cyst is related to a lateral canal. Located at the side of the tooth instead of the apex.

64
Q

What is a dentigerious cyst?

A

A developmental odontogenic cyst. Associated with crown of unerupted (and usually impacted) tooth eg mandibular 3rd molar or maxillary canine.

Cystic change of dental follicle.

Most common in 2nd to 4th decades.

Affects males more than females

More common in the mandible

65
Q

What are some clinical and radiological features of a dentigerous cyst?

A

Corticated margins attached to cemento-enamel junction of tooth.

Larger cysts may begin to envelope root of tooth.

May displace involved tooth

Tend to be symmetrical initially.

Larger cysts may begin to expland unilaterally.

Variable displacement of cortical bone ie bony expansion

66
Q

How can you identify a dentigerous cyst vs an enlarged follicle

A

Consider cyst if follicular space >4mm (measure from surface of crown to edge of follicle)

Assume cyst if >10mm

Consider cyst if radiolucency is asymmetrical.

67
Q

What is an odontogenic keratocyst?

A

A developmental odontogenic cyst. No specific relationship to teeth.

Most common in 2nd and 3rd decades

More common in males than females

More common in the mandible, and more common posteriorly

Often have scalloped margins.

25% are multilocular

Often cause displacement of adjacent teeth.

Root resorption uncommon.

Characteristic expansion (can expand mesio distally without bucco lingual expansion)

High chance of recurrance due to thin friable lining and difficulty of surgery

68
Q

What syndromes can be associated with odontogenic keratocysts?

A

Basal cell naevus syndrome;

multiple OK

multiple carcinomas

plamar and plantar pitting

Calcification of intracradial dura mater known as Gorlin-Goltz syndrome

69
Q

What is a naso palatine duct cyst?

A

Developmental non odontogenic cyst.

Arises from nasopalatine duct epithelial remnants

Most common in 4th to 6th decades

More common in males than females

Often asymptomatic

Pt may note a salty discharge

Larger cysts may displace teeth or cause swelling in palate

Always involve the midline but not always symmetrical

Non keratinised stratified squamous and modified respiratory

70
Q

What is the radiographic presentation of a nasopalatine duct cyst?

A

Need a PA and/or standard maxillary occlusal radiograph.

Corticated radiolucency between/over roots of central incisors

Often uniloclear

May appear heart shaped due to superimposition of anterior nasal spine.

CBCT indicated for surgical planning

If radiolucency <6mm assume it is the incicive fossa

Incisive fossa not visibly corticated

71
Q

What is a solitary bone cyst?

A

Non odontogenic cyst without an epithelial lining.

AKA simple/traumatic bone cyst

Most common in 2nd decade

Males more than females

Mandible more than maxilla

Can occur in association with other bone pathology eg fibro-osseous lesions

72
Q

What is the clinical presentation of a solitary bone cyst?

A

Usually asymptomatic and an incidental finding

Rarely pain or swelling

Radiologically;

Majority in premolar/molar region of mandible but can also occur in non tooth bearing areas

Variable definition and cortication

May have scalloped margins giving a pseudoloclear appearance

May project up between the roots of adjacent teeth

73
Q

What is a stafne cavity?

A

Not a cyst but commonly mistaken as one. It is actually a depression in the bone. (cortical bone preserved)

Only occur in mandible and almost exclusively lingual.

Contains salivary or fatty tissue

Most common in 5th and 6th decades

Often in angle or posterior body

Often inferior to IAC

Asymptomatic

Well defined, often corticated radiolucency

Rarely displaces adjacent structures

74
Q

What are the 3 options for obtaining material from a cyst for histology?

A

Aspirational biopsy (drainage of contents)

Incisional biopsy (partial removal)

Excisional biopsy (complete removal)

75
Q

Describe an aspiration biopsy

A

Wide bore needle

5-10ml syrings

Can get; air, blood, pus or cyst fluid

Cyst fluid can be clear straw coloured fluid in inflammatory or developmental cysts. White or cream semi solid may indicate keratocyst

May be unable to withdraw plunger

76
Q

Describe an incisional biopsy

A

Taken to obtain a sample of the lining for histological analysis

Usually under LA

Select area where lesion appears superficial.

Raise mucoperiosteal flap

Remove bone as required using rongeurs or a round bur

Incise and remove a section of linin

Procedure may be combined with marsupialisation

77
Q

What is enucleation of a cyst

A

All of the cystic lesion is removed.

Treatment of choice for most cysts.

Advantages; whole lining can be examined pathologically, primary closure, little aftercare needed.

Contraindications/disadvantages; Risk of mandibular fracture with very large cysts

Dentigerous cyst? May wish to preserve tooth

Old age/ill health

Clot filled cavity may become infected.

Incomplete removal of lining may lead to recurrance

Damage to adjacent structures

78
Q

What is marsupialisation of a cyst? and what are the indications?

A

Creation of a surgical window in the wall of the cyst, removing the contents of the cyst and suturing the cyst wall to the surrounding epithelium.

Encourages the cyst to decrease in size and may be followed by enucleation at a later date.

Idications; if enuculeation would damage surrounding structures eg IAC

Difficult to access area

May allow eruption of teeth affected by the dentigerous cyst.

Elderly or medically compromised patients unable to wishtand extensive surgery

Very large cysts that would risk jaw fracture if enucleation was performed

Can combine with enucleation as a later procedure

79
Q

What are some advantages of marsupialisation?

A

Simple to perform

May spare vital structures.

80
Q

What are some contraindications/disadvantages of marsupialisation?

A

Opening may close and cyst may reform

Complete lining not available for histology

Difficult to keep clean, lots of aftercare needed.

Long time to fill in

An obturator is used to keep marsupialisation window open

81
Q

Identify

A

Condyle of mandible

82
Q

Identify

A

Coronoid process

83
Q

Identify

A

Sigmoid notch

84
Q

Identify

A

Ramus of mandible

85
Q

Identify

A

Styloid process

86
Q

Identify

A

Styloid ligament ossicles

87
Q

Identify

A

Inferior border of mandible

88
Q

Identify

A

External oblique line

89
Q

Identify

A

Posterior border of ramus

90
Q

Identify

A

Submandibular fossa

91
Q

Identifyy

A

Genial tubicles

92
Q

Identify

A

Body of hyoid bone superimposed on mandible

93
Q

Identify

A

Tongue

94
Q

Identify

A

Palatoglossal air space

95
Q

Identify

A

Soft palate

96
Q

Identify

A

ear

97
Q

What is the incidence of odontogenic tumours?

A

1% of all lesions sent to histopathology come back as OT

Benign>malignant 100:1

Most asymptomatic and discovered investigating unerupted teeth

Pain usually secondary to infection

Most arise within bone

98
Q

What are the three classifications of odontogenic tumours?

A

Epithelial

Mesenchymal

Mixed

ONLY mixed tumours can have dentine/enamel formation

99
Q

Give description of ameloblastoma

A

Benign epithelial tumour

Locally destructive but slow growing

Typically painless

Most common in 4th to 6th decades

80% occur in posterior mandible

Male more than Female

Radiologically 85% multicystic. Unicystic carries lower recurrance rate

Histilogica

100
Q

What types of tumours can fall into the different classifications?

A

Epithelial; ameloblastoma. Adenomatoid odontogenic tumour. Calcifying epithelial odontogenic tumour

Mesenchymal; odontogenic myxoma

Mixed; odontoma

101
Q

Give the incidence and some features of ameloblastoma

A

Benign epithelial tumours

Locally destructive but slow growing

Typically painless

Most common in 4th to 6th decades

80% occur in posterior mandible

male more than female

Radiological; 85% multicystic, unicystic lower rate of recurrence

Histological; follicular, flexiform, desmoplastic

Margins well defined and corticated. Potentially scalloped

Adjacent structures can be displaced, thinning on bony cortices ‘knife edge’ extended root resorption

102
Q

What is the management of an ameloblastoma/

A

Surgical resection with margin

Recurrance relatively common, up to 15%

Risk of malignant change <1% Ameloblastic carcinoma

103
Q

AOT Adenomatoid Odontogenic Tumour

A

Benign epithelial tumour

Classic presentation - unilochlear radiolucency with internal calcifications around crown of unerupted maxillary canine

Incidence/presentation;

3% of odontogenic tumours

Most common in 2nd decade

female more than male

Mostly anterior maxilla

75% associated with unerupted tooth

Similar to dentigerious cyst but attached to CEJ

Impedes eruption

Unilocular

Majority have internal calcifications

External root resorption is rare

104
Q

CEOT

A

Benign epithelial tumour

Most common in 5th decade

male more than female

Post mandible most common

Slow growing

50% associated with UE tooth

Internal radiopacities

105
Q

Odontogenic myxoma

A

Benign mesechymal tumour

Most common in 3rd decade

female = male

mandible more than maxilla

well defined

small lesions unilocular

larger soap bubble appearance

slow growth m-d

scallops between tooth, may displace if large

management; curettage or resection. 25% recurrance rate

106
Q

Odontoma

A

Benign mixed tumour

Malformation of dental tissue

Similarities to teeth; do not grow indefinitely, surrounded by dental follicle, lie above IAC

Most common in 2nd decade

Female = male

Compound; ordered dental structures (resembles multiple mini teeth) more common in maxilla

Complex - disorganised mass more common in post mandible

Final Flashcards (13 decks)

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