Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

4th year > Radiography > Flashcards

Radiography Flashcards

1
Q

Describe the 3 radiation protection principles.

A

Justification- must do more good than harm.

Optimised- ALARP- As low as reasonably practiciple

Limitation- individual dose limits are used to ensure no one has an unacceptable exposure.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the inverse square law and why is it relevant to radiographs?

A

The X-ray follows this law.

That the further away from the source, the intensity of the x-ray reduces.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the pattern of attenuation?

A

This is how we produce a radiographic image using the pattern produced by the interaction of x-rays with matter.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Compare the ways that an x-ray can be absorbed?

A

Full absorption (e.g. amalagam showing up white on an x-ray)

Partial absorption and scatter- individual components of the beam change direction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Name this type of radiograph

A

Bitewing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Name this type of radiograph

A

Periapical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Name this type of radiograph?

A

Occlusal. There are 2 types:

  • True - cross sectional
  • Oblique- image receptor is put in the occlusal plane.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Name this type of radiograph

A

Panoramic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Name this type of radiograph

A

Cephalometric

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Name and describe the two legislations in the uk for radiation.

A

IRR17- for the general public and occupational exposure (those paid to be exposed to radiation)

  • Employer must (register for x-rays, consult a radiation protection advsier and ensure radiation risk assessments are carried out)
  • Controlled areas must be defined & local rules for that area.

IRMER- For Medical exposure of patients and those not paid for exposure (e.g. patient’s parents)

  • Patient identifcation procedures
  • Staff entitlement procedures
  • procedures to provide information.
  • 4 roles (referrer/ practioner/ operator/ employer.)
  • Clinical evaluation.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How often and why do we test radiographic equipment?

A

To ensure It :

  • is working correctly
  • Is administering the expected dose level.

We test it:

  • Every 3 months by a staff member
  • Every 1-3 years by specialist staff.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the ideal projection geometry and why can we not achieve it?

A

These are the principles we want for achieving a good image:

  • That the image receptor and object are in contact- cannot fully contact as the tooth is supported by bone.
  • That the x-rays are a parallel beam- x-ray beam is divergent so cannot be parallel.
  • That the image size is indentical to the object size- we can’t do this because the divergent beam causes mangification.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is paralleling.

A

Where the image receptor and object are parallel but not touching.

The central ray is perpendicular to the long axis of the tooth.

Outer rays are at slight angles (the x-ray is divergent)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the FSD?

A

The focus to skin distance. This helps us line up the x-ray beam with the patient.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What FSD do we use for Radiography and why?

A

We use a long FSD to reduce magnification.

The longer FSD makes the x-ray beam near parallel compared to the diverging x-ray beam of a short FSD.

e.g. 20cm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is rectangular collimation?

A

A device that reduces the dose of the x-ray and allows us to control the shape and size of the x-ray beam.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the blue film holder used for?

A

Anterior teeth.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the yellow film holder used for?

A

Posterior teeth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the red film holder used for?

A

Bitewings.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the 3 components of a film holder?

A

Bite block

Beam aiming device

Image receptor support

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Compare the curve of Spee and the curve of Monsoon?

A

Curve of spee is the upward slope of the teeth as seen in a radiograph

Curve of monsoon is that the buccal cusps of molars are slightly higher than the palatal cusps.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the bisecting angle technique?

A

When the receptor and the object are touching but not parallel.

They are touching at the crown & far apart at the apex.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the soft tissue checkpoints for a maxillary occlusal radiograph?

A

Alatragus line should be paralell to the floor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the horizontal angle we want for radiographs?

A

90* to the line of the arch.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the centuring point of the maxilla for a periapical

A

On the ala tragus line

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the centuring point of the maxilla for an oblique occlusal?

A

1cm above the ala-tragus line.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the centuring point of the mandible for a periapical

A

1cm above the lower border of the mandible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Why does the vertical angle drop as you reach the back of the mouth?

A

As the teeth become more upright as we reach the molars.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is a Dental Panoramic Tomograph?

A

A radiograph which displays details from a specific image layer of the teeth with specific resolution.

Also known as DPT/DPR/OPT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Describe linear Tomography

A

We form images by the continuous movement of the x-ray machine and receptor.

The X-ray machine moves from L to R.

The receptor moves from R to L.

The focal trough is what we want to see and this remains in one place.

We use 2 location centres to achieve this (an anterior and a posteiror location centre)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Compare taking panoramic radiographs of anterior teeth and posterior teeth

A

Anterior teeth:

  • Slower beam passage through the teeth
  • Slower image receptor movement to match.

Posterior teeth

  • faster beam passage through the teeth
  • faster image receptor movement to match.

If the speeds don’ t match there will be image distortion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

How does the distance from the rotation centre to the teeth affect radiographs?

A
  • It affects the width of the layer in focus (focal trough)
  • Can cause horizontal distortion if the patient is in the incorrect position.
  • Ghost images can be formed.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Why is the canine position so important in an OPT?

A

This allows you to prevent distortion of the image by compensating the speed dependent onthe canine position.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What are ghost images?

A

A second image of something in the wrong place formed by the beam x-ray going through the back of the object again at the position of the premolars.

It will always be:

  • Higher due to the negative 8* beam angle
  • horizontally magnified (i.e. wider)
  • Further forward.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

How frequently should you take bitewings for a high risk caries patient?

A

Every 6 months

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

How frequently should you take bitewings for a moderate risk caries patient?

A

Anually

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

How frequently should you take bitewings for a low risk caries patient?

A

Primary teeth (12-18 months)

Permanent teeth (2 years)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What does this image show?

A

Cervical burnout.

The Mesial and distal area between the enamel margins and crest of bone appear radiolucent.

This is commonly found in periodontal disease where the drop in bone level creates the larger distance between the enamel margins and crest of bone. There is a lower absorption of x-rays.

This looks similar to root surface caries (but cannot be seen clinically)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

what are the soft tissue checkpoints for a mandibular occlusal?

A

Corner of the mouth to the tragus of the ear are parallel.

Head is tilted backwards.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What is the centuring point of the mandible for an oblique occlusal?

A

Through the lower border of the mandible.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Distinguish between the two types of restorative mateiral in this radiograph:

A

Brighter is amalgam.

Matter is composite.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Compare these two radiographs:

A

Left image- Internal root resorption (results from chronic pulpitis)

Image shows radiolucency within canal space

Right image- External root resorption (originates in the PDL)

image shows radiolucency overlying the root canal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Compare the continuous and characteristic spectrum

A

Continuous spectrum -

Electron gets close to the nucleus & is slowed down and defelected.

Kinetic energy is lost and released as photons (low energy)

Characteristic spectrum

Electron collides with an inner shell electron

Inner shell e- is displaced to an outer shell or completely knocked from the atom.

The atom is unstable so the electrons re-arrange producing the x-ray photon.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What is the filament?

A

A cathode (negative) used to pull the electrons towards the positive side of the electron tube.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What is the function of the transformer?

A

To increase the voltage from the mains supply to kVp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What is the target surround and why do we need it?

A

A copper layer that surrounds the target to remove heat. (99% of the energy produced by the target is heat)

47
Q

What is the function of the evacuated glass envelope?

A

It is a vaccum that prevents the risk of interaction of electrons with air atoms prior to meeting the target.

48
Q

What is the sheilding in a tubehead?

A

This is a led surrounding that absorbs the x-rays in order to cap the dose rate.

49
Q

What is the filtration of the tubehead?

A

An aluminium layer used to interact and get rid of the low x-rays that we don’t want. (the high energy x-rays can travel through this)

50
Q

Compare the process of the Photoelectric and Compton Effects

A

Photoelectric

X-ray photon interacts with an inner shell & disapears

The electron knocked out (photoelectron) has some kinetic energy and can have other interactions.

This leaves an empty space & causes the atom to re-organise.

Characteristic radiation is released due to the movement between shells.

Compton

X-ray photon interacts with an outer shell electron (outer electron is ejected)

There is lots of energy left in the x-ray photon (Scatter photon)

The scatter photons journey is altered as it leaves the atom & it can be involved in other compton or photoelectric reactions. .

51
Q

What is does the photoelectric effect contribute to?

A

The image, as the photons interact with material, resulting in a varied interaction with the image receptor.

52
Q

How does the energy level affect the direction of scattered photons?

A

High energy scatter photons travel forward.

Low energy scatter photons travel backwards.

53
Q

What sort of materials is the compton effect more likely to happen to and why?

A

Dense materials (more electron dense) as it is more likely that an incoming photon is going to bump into the electrons.

54
Q

Compare how the photoelectric effect and Compton effect impact the image and dose.

A

The photoelectric absorption produces the image and increases the dose.

The compton effect only increases the dose.

55
Q

Compare direct and indirect damage to DNA

A

Indirect damage- Radiation interacts with water in the cell to produce free radicals (that cause damage)

Direct damage-Radiation interacts directly with atoms of a DNA molecule.

56
Q

Compare the deterministic effects and Stochastic effects of radiation

A

Deterministic Effect-

Only occurs above a certain dose & the severity is related to the dose.

e.g. hair loss due to chemotherapy

Stochastic Effect-

There is no threshold for the effect.

These can be somatic (causing a disease or disorder)

Genetic (causing abnormalities in descendants)

57
Q

What are tissue weighting factors?

A

A number used to account for the varying sensitivites of different organs and tissues to radiation.

58
Q

Compare the different types of dose

A

Absorbed dose- energy deposited by radiation

Equivalent dose- Dose taking into account the damage to the specific tissue (absorbed dose x tissue weighting factor)

Effective dose- the dose for the whole body (sum of equivalent dose x tissue weighting factor for each organ involved)

59
Q

What is a cephalometric radiograph?

A

A standardised and reproducable form of skull and facial bone radiography

60
Q

What do we use a cephalometric radiograph for?

A

Orthonathic surgery (pre-op and post op)

Patients with skeletal/vertical or antero-posterior discrepancy

Patient’s requiring fixed or functional appliance therapy (for labio-lingual movement of incisors)

Implant planning

61
Q

What is the MSP?

A

Mid sagital plane (Or line)

62
Q

Compare the OM and FP lines.

A

Orbito-meatal line- a line from the outer corner of the eye to the centre of the external auditory meatus.

Frankfort plane- From the external auditory meatus to the lowest part of the infra-orbital rim.

There is a 10° difference.

63
Q

Compare the two types of lateral radiography

A

True-

The film and midsagital line are paralell.

X-ray beam is perpendicular to them both.

Oblique-

The film and MSP are not parallel

X-ray beam is oblique to both of them.

uncommon.

64
Q

What is the distance between the source and the patient’s MSP for a cephalometric radiograph

A

5 feet or 152.4cm

65
Q

What does this image show?

A

An unerrupted third molar.

66
Q

What does this radiograph show?

A

A permanent canine coming through (They are found higher up than premolars)

67
Q

What does this radiograph show

A

The tooth has erupted but the root is not fully formed.

68
Q

Which teeth are more likely to be congenitally absent?

A

the last tooth of each group of teeth

Lateral incisor

Second premolar

third molar

69
Q

How do we grade a radiograph?

A

You need to know what the radiograph should contain. Then grade.

A- Diagnostically acceptable (No errors/ minimal errors/sufficient quality to answer the Q)

N- Diagnostically unacceptable .

70
Q

What is radiographic localisation?

A

Using radiographs to determine the position.

71
Q

When would we use radiographic localisation?

A

To find out:

  • Position of unerupted teeth
  • Location of roots/root canals
  • Relationship of pathological lesions
  • Trauma
  • Soft tissue swellings.
72
Q

Compare the two view choices used for radiographic localisation?

A

Right angle- using two radiographs at right angles to each other. (e.g. panoramic and lower true occlusal

A known projection geometry -This requires a horizontal or vertical tube shift in order to interpret the image (but we need to know the difference in projection)

73
Q

What is paralax?

A

where an aparent change in the position of the object is caused by an actual change in the observers position.

74
Q

What are the rules of thumb for paralax

A

My PAL goes with me.

If the object in question moves in the same direction as the source (it is LINGUAL/PALATAL)

75
Q

Compare the two types of tube shift.

A

Horizontal tube shift- The same radiographic view but centred on different places. (e.g. two periapicals)

Vertical tube shift- different views (e.g. a panoramic and an oblique occlusal)

76
Q

Compare paralleling and bisecting angle technique

A

Parallelling- the image receptor and object are not touching but are parallel.

Used for periapicals/bitewings

disadv-more limited by mouth anatomy & if the source is too close we get magnification.

Bisecting techinque- the receptor and object are touching but not parallel.

Used for: Periapicals/oblique occlusals/true occlusals.

Disadv- wrong angle can cause distortion.

77
Q

What are contingency plans and why do we need them?

A

These are immediate actions to be taken in the instance of a reasonably foreseeable radiation incident.

So we know what do to if certain incidents occur.

78
Q

What is meant by dose monitoring?

A

This is montoring :

  • The staff who enter the controlled area (should have an annual personal dose of 1msv)
  • The controlled area itself (is it big enough? Do we need to count adjacent rooms aswell)
79
Q

When would we use other maxillofacial views for a radiograph

A

When we cannot use a cone beam CT.

80
Q

What is a grid and describe the function?

A

A grid of led strips used to get images as clear as possible (cuts out any x-rays not going straight)

81
Q

What is the disadvantage of using a grid?

A

Need to increase the dosage to achieve the same number of photons reaching the film.

82
Q

Name this line used for patient positioning

A

Frankfort plane

83
Q

Name this line used for patient positioning

A

Orbitomeatal line

84
Q

What does a lateral skull radiograph show?

A

A lateral view of the whole skull as well as facial bones and the upper cervical spine.

85
Q

Describe the posteroanterior view and explain why it is more commonly used.

A

X-ray beam enters from behind the pateint into the receptor infront of the patient.
It is more commonly used
-to reduce mangification (the things we want to see are closer to the receptor)
-Reduce dose (low energy photons are attenuated before they reach radiosensitive tissues (e.g. lens)

86
Q

What is the occiptomental view and when would we take it?

A

When the x-ray beam comes through the occipital region of the head and comes out at the mental region of the cin.

Middle 1/3 facial or coronoid process fractures.

87
Q

How is the occiptomental radiograph taken?

A

Nose to chin position.
Orbitometal line at 45 to the image receptor.

88
Q

What is the posteroanterior mandible view and when is this taken?

A

Beam enters behind the head and comes out at the front with the receptor in front of the face.

This is taken for fractures of the angle of the mandible.
Cysts and tumours

89
Q

How do we take a posterior-anterior mandible radiograph?

A

In what radiographs do we see all the margins of the maxillary sinus

90
Q

What is shown in this radiograph & how does it influence treatment?

A

Hypercementosis. (material around the root is the same colour as the tooth)
This affects your ability to extract the tooth.

91
Q

Name and describe what is shown in this radiograph

A

Coritcation
The white line around the lesion shows the cortical margin.
(Lost if the lesion is infected)

92
Q

What becomes radiolucent in a radiograph?

A

Previously opaque materials
e.g. cystic lesions of bone.
Caries in tooth.

93
Q

What causes radiopaque in a radiograph

A

An increase in attenuation due to changes in natural tissue.
e.g. increased density. Increased thickeness (Overlap)
Alteration
Replacing air with something (e.g. soft tissue in a sinus)

94
Q

Compare unilocular and multiocular lesions

A

Unilocular- one obvious lesion (simple shape)
Multiocular- Scalloped margin or internal divisions.

95
Q

A lesion has displaced other structures. What does this tell us about the lesion’s growth.

A

Slow growing lesion (bone is remodelling)

96
Q

A lesion has expanded other structures. What does this tell us about the lesion’s growth.

A

Slow growing lesion (bone is remodelling)

97
Q

A lesion has resorbed other structures. What does this tell us about the lesion’s growth.

A

Fast growing lesion (body does not show any response)

98
Q

How does a CT produce images?

A

It produces images as slices of a patient’s body.

99
Q

Compare the views of a cbct?

A

Axial- from below
Coronal- from the front
Sagittal- from the side.

100
Q

Compare conventional CTs to a cone beam CT

A

Conventional- Fan shaped beam. Multiple rotations. Shows soft and hard tissues.

Cone beam- cone shaped beam. Single rotation.Only shows hard tissues.

101
Q

Why do we image the salivary glands?

A

To look for obstructions (mucous plugs/salivary stones/ neoplasia)
Dry mouth (sjrogrens)
Swelling (e.g. mumps)

102
Q

How does an ultrasound work?

A

The use of high frequency sound waves (we cannot hear) and a coupling agent to get the sound waves into tissues.

The image comes out upside down .

103
Q

What are we looking for in an ultrasound of the salivary gland?

A
  • Parenchymal pattern (tissues within the gland)
  • Vascularity
  • Ductal dilation- to allow better visualisation we give a sialoguge to stimulate the salivary gland.
  • Neoplastic masses
104
Q

What is sialography?

A

Injection of a iodinated radiographic contrast into the salivary duct. 2 radiographs are used (one which is delayed so we can identify an obstruction)

105
Q

What are the indications for a sialography?

A

Suspected blockages or stricture.
Planning for access for interventional procedures

106
Q

What are the advantages and disadvantages of a sialography?

A

Adv.
No need for LA.
A small volume of contrast is used.
It is isomolar and water based so if it gets into tissues it won’t cause damage.
Disadv-
Discomfort
Swelling
If there are any signs of infection we cannot use it as it would push the infection further back.
Patient could also be allergic to contrast.

107
Q

What gland is shown in this radiograph?

A

Parotid gland. ( tree in winter)

108
Q

What gland is shown in this radiograph?

A

Submandibular gland (bush in winter)

109
Q

How do we manage a salivary stone?

A

**Remove it: **
* The stone must be mobile
It must be located:
Within the lumen on the main duct distal to the posterior border of the mylohyoid
Distal to the hilum
At the anterior border of the parotid gland.

The duct needs to be patent and wide to allow passage of the stone

110
Q

What is the radiographic appearance of a patient with sjogren’s

A

We lose the outline of the gland- it just merges into all the other tissues.

111
Q

How would a benign tumour look in an ultrasound?

A

Well defined
Encapsulated
Peripheral vascularity
No lymphadenopathy.

112
Q

Compare an MRI to a CT

A

MRI- no radiation dose. Takes longer. Contradicated for pacemakers/cochlear implants/ if patients are claustrophobic)

CT- radiation dose. quicker . Risk of allergy to contrast.

113
Q

What is a PET scan

A

Positron Emission Tomography where the radioactive fluorine labelled glucose is injected and goes to the metabolically active tissues.
This is used for unknown primary tumours/ distance spread and as a follow up to check for recurrence.

4th year (51 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions