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BDS4 Revision > Radiology > Flashcards

Radiology Flashcards

1
Q

List 2 radiographic views you would use to examine a mandibular fracture.

A

2 Plain views at 90 degree angles to each other
OPT + posteroanterior mandible

Other radiographs:
* Occlusal
* Lateral oblique
* Towns view
* SMV
* CT scan or CBCT

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2
Q

(OPT provided)
Identify the;
* Condyle
* Hard palate
* Zygomatic buttress
* Styloid process
* Soft palate
* Hyoid bone
* Nasal septum
* Ear lobe
* Bite peg
* Ghost image of opposite lower mandible

A
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3
Q

What 2 imaging methods should you use to confirm a zygomatic-orbital complex fracture?

A

occipitomental view at 15 and 30 degrees

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4
Q

List and describe two common radiographic views used to assess the position of an unerupted second premolar tooth which is partially erupted. (4)

A

2x periapicals at differing angles to one another

(maxillary) oblique occlusal and OPT
= parallax

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5
Q

Explain the difference between horizontal and angular periodontal bone loss defects on a radiograph.

A

Horizontal bone loss- base of the pocket is located coronally to the alveolar crest.

Vertical bone loss-
Apical end of the pocket is located below the alveolar crest.

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6
Q

What radiograph(s) would you request before XLA of an 8?

A

OPT

CBCT - If tooth appears high risk to the IDN
only indicated if the results of this would alter tx plan

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7
Q

List 7 radiographic signs of M3M proximity to the IAN.

A

Root:
1. Darkened root where it is crossed by canal
2. Deflection of root
3. Narrowing of root.
4. Dark and bifid root (split/divide over canal)

IADN:
5.Interuption of white line (Lamina dura) of IADC
6.Diversion/deflection of IADC
7.Narrowing of IADC

High risk;
1. Diversion/deflection of the inferior dental canal
2. darkening of the root where crossed by the canal
3. interruption of the white lines of the canal

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8
Q

Which radiographs would you request when imaging an unerupted upper canine? (4)

What imaging method do we use to localise this tooth?

A

Parallax:
vertcial or horizontal

2x periapicals at differing angles to one another
or
maxillary occlusal and OPT

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9
Q

Give 4 differential diagnoses for a multilocular lesion in the mandible.

A

Ameloblastoma

odontogenic keratocyst

cherubism

Browns tumours in primary hyperpparathyroidism

central giant cell granuloma

Odontogenic myxoma.

Fibro-osseous lesions

osteomas

Calcifying epithelial odontogenic tumour.

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10
Q

Provide 2 examples of developmental bone pathology

A

Tori- benign lump of bone
Osteogenesis imperfecta- weak bone/multiple fraactures
Achondroplasia -poor enchodonral ossification
fibrous dysplasia- bone replaced by fibrous tissue.

Removed osteitis from answers (They are inflammatory pathology)

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11
Q

Provide 2 examples of inflammatory bone pathology

A
  • alveolar osteitis -dry socket
  • osteomyelitis -rare endogenous infection
  • Garres sclerosing osteomyelitis
  • Rarefying osteitis - localised bone loss in response to infection
  • scleroising osteitis- increase in bone density in response to low grade inflammation
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12
Q

Provide 2 examples of neoplasm bone pathology

A
  • Osteoma- benign
  • Osteoblastoma- likely to be a cementoplasm in the jaw
  • Ossifying fibroma - fibrous tissue becoming bone.
  • Cementoblastoma- neoplasm attached to the root.
  • Cemento-osseus dysplasia
  • Osteosarcoma- malignant (rare)

Ewings sarcoma
Chondrosarcoma

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13
Q

Provide 2 examples of metabolic bone pathology

A

Osteoporosis- more bone resorption (weaker bone)
Rickets and osteomalacia (Vit D deficency)
Hyperparathyroidism
Paget’s disease -disturbance between resorption and bone deposition

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14
Q

Describe what causes anterior teeth to be distorted on an OPT.

A

outside focal trough

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15
Q

Describe what causes a blurry OPT image.

A

Patient movement (objects become outwith the desired image layer)

(wavy lower border of mandible)

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16
Q

Describe what causes an OPT image which is too wide.

A

Canine behind vertical canine guide
= teeth are closer to the x-ray source than expected
= the speed of beam is slow and the speed through the Image Receptor is fast
= unmatched speeds causes distortion

We check the canine line on an OPT so we can compensate for this.

17
Q

Describe how we can reduce positioning errors for OPT imaging.

A

Utilising reference planes e.g. frankfort plane parallel to floor

utilising the positioning lights e.g. canine line, centre line, Frankfort plane line

utilising the temple rests, chin rest and bite block

18
Q

Give 3 characteristics of a ghost image

A

Further forward (due to change in anterior posterior position)

higher up (vertical beam angulation)

horizontally magnified

on the opposite side

19
Q

Give 3 ways in which we can reduce patient dose.

A

rectangular collimation 40x50mm = 25% dose reduction (compared to circular)

FSD at least 20cm

using faster film speed (min E & F = faster )

aluminium filtration to absorb low energy photons which have been scattered

lead absorption to absorb excess photons

limit exposures

20
Q

Describe the comptom scatter vs photoelectric effect.

A

Difference is:
Compton effect = scatter & absorption of the photon
Photoelectric = complete absorption of the photon (does not reach the film)

CE: scatter & absorption
X-ray photon interacts with losely bound electron in outer shell
photon energy greater than electron binding energy
electron is ekected taking some of the photons energy as kinetic energy
= atom is positively charged

PE: absorption
X-ray photon interacts with inner shell electron
photons energy is higher than the electrons binding energy
Photon disappears
The energy not used to overcome the electron binding energy is given to the electron = photoelectron
The photoelectron is ejected
Atom has a void where the electron has been lost (+ve charge) and an electron from the outer shell drops down to fill the void
difference in energy between the 2 shells is emitted as light/heat energy
the void in the outer shell is filled by free electrons
= complete absorption of the photon energy = photon does not reach the film

21
Q

What metal is used for absorption of excess photons?

A

Lead

22
Q

List another metal which is used in the x-ray tube head.

A

Copper - heat conductor

Tungsten - in the target

23
Q

List the 5 safety features advised in IRR17.

A

Ensure controlled area has a warning sign

When exposure being taken = light and audible sound for the full duration

Exposure automatically stopped when finger taken off the exposure button

Intra-oral has a controlled area of 1.5m from the primary beam

An entire room for CBCT - the full room is the controlled area

The anual dose limits
6mSv per year (Staff)
1mSv per year (general public)

24
Q

Describe ALARP.

A

as low as reasonably practicable (part of optimisation)

25
Q

How do we achieve ALARP?

A

rectangular collimation 40x50mm = 25% dose reduction (compared to circular)

FSD at least 20cm

using faster film speed (min E & F = faster )

aluminium filtration to absorb low energy photons which have been scattered

lead absorption to absorb excess photons

limit exposures

26
Q

What is a radiation protection supervisor?

A

Part of the IRR17 legislation:
A radiation protection supervisor should be consulted on radiation safety (equipment checks/safety feature testing/radiation risk and dose assessment)

This is someone who meets the Health and Safety executive requirements to advise on radiation safety.

They ensure compliance with Regulations in respect of work carried out in any area subject to local rules

27
Q

Compare the parallelling technique with the bisecting angle technique.

A

Paralelling- where the image receptor and object are parallel but not touching.
Beam is divergent/perpendicular so image receptor and object is some distance apart. A long spacer cone is used to achieve a long x-ray FSD 20cm to redue magnification. (e.g. bitewings)

Bisecting angle technique- The image and receptor are partially touching but not parallel. The x-ray beam is perpendicular to the image receptor and the objects are close together at the crowns but apart at the apex.
We use a long x-ray FSD of 20cm . (e.g. occlusals)

28
Q

Why should we report radiographs? (3)

A

Record of the radiograph being taken

record of exposure justification??

Medico-legal reasons

Audit purposes

29
Q

According to IRMER2017, describe the role of the employer. (5)

A

Establishment of;
general procedures
protocols
quality assurance programmes
clinical audits
accidental/unintended exposures

30
Q

According to IRMER2017, describe the role of the referrer.

A

Who? registered healthcare professional
(Refers to practitioner for exposure)

The referrer must supply the practitioner with sufficient medical data (such as previous diagnostic information or medical records) relevant to the exposure requested by the referrer to enable the practitioner to decide whether there is a sufficient net benefit/justification.

31
Q

According to IRMER2017, describe the role of the practitioner. (4)

what must they consider? (4)

A

Who? registered healthcare professional

The practitioner:
Authorises request
confirms justification of an exposure
ensuring dosages are ALARP
compliance with the employers procedures.

Practitioner must consider;
Efficacy
Benefits - directly and in society
Risk to the individual
Alternatives

32
Q

According to IRMER2017, describe the role of the operator.

A

Who? - anyone who caries out the practical aspects that can affect patient dose. (Takes the x-ray)

The operator is responsible for each practical aspect which is carried out as well as for any authorisation given in accordance with the regulation.
Will not perform the exposure unless it is authorised and justified by the practitioner

Taking the radiographs
Annotating the images
Sending them to PACS
Recording the findings
Select equipment and method to limit dose
Follow employers procedures

BDS4 Revision (14 decks)

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