Radiographic Techniques

Question 1

What are the three basic components of radiographs?

Answer 1

X-ray source
Object
Receptor

Question 2

What is key to the quality of an image?

Answer 2

The relationship of X-ray source, object and receptor to one another

Question 3

What are three types of intra-oral radiograph?

Answer 3

periapical

bitewing ( horizontal and vertical)]

occlusal (maxilla and mandible)

Question 4

When taking an intra-oral radiograph, where would the receptor be placed?

Answer 4

Inside the mouth

Question 5

When taking an extra-oral radiograph, where would the receptor be placed?

Answer 5

Alongside the patient

Question 6

What are five types of extra-oral radiographs?

Answer 6

dental panoramic tomogram
lateral cephalogram
postero-anterior mandible
lateral oblique mandible
Occipital-mental views of facial bones

Question 7

On a peri-apical radiograph, what should be visible?

Answer 7

The crown to the apices of the root, and inter-proximal spaces

Question 8

What are the limitations of a horizontal bitewing?

Answer 8

You are not able to visualise the roots

Question 9

What radiograph would you consider taking if you wanted to assess bone levels of posterior teeth?

Answer 9

Bitewing, either horizontal or vertical

Question 10

What type of extra-oral radiograph is described:

The x-ray tube rotates round the patients head with a constant long exposure of 14 seconds, forming an image of the patient’s teeth and supporting structures

Answer 10

DPT

Question 11

What type of extra-oral radiograph is described:

A standardised and reproducible form of skull radiography, used extensively in orthodontics to asses the relationships of the teeth to the jaws and the mandible to the rest of facial skeleton

Answer 11

Lateral cephalogram

Question 12

What type of extra-oral radiograph is described:

Shows fractures of the mandible and is used in conjunction with a DPT. it requires two views taken at right angles to one another to show full extent of fracture.

Answer 12

Posterior-anterior mandible

Question 13

It is common for there to be multiple fractures in the mandible. True or false?

Answer 13

True

Question 14

What type of extra-oral radiograph is described:

Most commonly carried out in a dental hospital in children that cannot tolerate bitewings. Also carried out on adults for, mandibular fractures if a DPT is not available.

Answer 14

Lateral oblique mandible

Question 15

Q
What type of extra-oral radiograph is described:

Most commonly carried out in the first instance when patient reports with facial trauma. Shows fractures of the orbit, maxilla and zygomatic arches. Two views are taken, the first angle at 10 degrees and the second angle at 30 degrees.

Answer 15

Occipito-mental views of facial bone

Question 16

Q
When taking an occipital mental view of the facial bones, why is it beneficial to take the films erect?

Answer 16

As this can help demonstrates fluid levels in antra

Question 17

Why are intra-oral radiographs in more detail that extra-oral?

Answer 17

Because the object is closer to the receptor

Question 18

What selection criteria helps decide the most appropriate form of imaging required when deciding what radiograph to take?

Answer 18

FGDP selection criteria for dental radiography

Question 19

What are the two main types of technique used for intra-oral radiographs?

Answer 19

paralleling technique
bisected angel technique

Question 20

What is the standardised intra-oral technique?

Answer 20

Paralleling technique

Question 21

When would you opt for the bisected angle technique over the paralleling technique?

Answer 21

When a patient cannot tolerate a holder in their mouth

Question 22

What is the main issue surrounding bisected angle technique?

Answer 22

Exposure of patients fingers to radiation as they are required to hold film in mouth

Question 23

What is the downside of the paralleling technique?

Answer 23

Holders are bulky and may not be tolerated by patient.

Question 24

What part of the mouth are blue holders used to visualise?

Answer 24

Anterior teeth

Question 25

What part of the mouth are yellow holders used to visualise?

Answer 25

Posterior teeth

Question 26

What colour of holder is used for bitewings?

Answer 26

Red holder

Question 27

What colour of holder is used for endodontic procedures?

Answer 27

Green holder

Question 28

What are the three components of holders?

Answer 28

Bite-block Indicator arm/rod Aiming ring

Question 29

What is the function of a bite-block?

Answer 29

Retains the receptor

Question 30

What is the function of the indicator arm/rod?

Answer 30

Fits into the bite-block

Question 31

What is the function of the aiming ring?

Answer 31

Slides onto the arm to establish alignment of collimator with receptor, guiding direction of the x-ray beam

Question 32

What is a receptor?

Answer 32

The object an image is taken on

Question 33

what type of receptors are used in dundee dental hospital?

Answer 33

Phosphor plates

Question 34

What reduces the variables in geometry?

Answer 34

Use of a holder

Question 35

What are examples of variables in geometry?

Answer 35

Receptor-tooth relationship X-ray tube position

Question 36

How should the vertical plane of the film be positioned?

Answer 36

So that it is parallel to the long axis of the tooth

Question 37

How should the horizontal plane of the film be positioned?

Answer 37

Parallel to the central arch under examination

Question 38

If the film isn’t parallel with the tooth vertically, what may happen?

Answer 38

Distortion of the image (teeth elongated and apices missing)

Question 39

If horizontal positioning of the film is incorrect what may happen?

Answer 39

Teeth appear overlapped, obscuring pathology

Question 40

What angle should the x-ray beam be to the tooth/receptor?

Answer 40

90 degrees ( right angle )

Question 41

If the angle of the x-ray beam is up too much, how will the image be distorted?

Answer 41

Elongation of image

Question 42

If the angle of the x-ray beam is down too much, how will the image be distorted?

Answer 42

Fore-shortening of image

Question 43

What is the rectangular attachment at the end of the x-ray tube known as?

Answer 43

Collimater

Question 44

what will help achieve the most diagnostic, reproducible image?

Answer 44

Having the 4 corners of the collimator fitting nicely into the aiming ring

Question 45

What two factors affect image size?

Answer 45

X-ray source to receptor distance Object to receptor distance

Question 46

Explain how the object comes to appear larger on the receptor

Answer 46

X-ray beam spreads out in all directions from the source and it continues to spread as it passes through the object, thus making it appear larger.

Question 47

What action should be taken in regards to the x-ray source in order to get a more accurate depiction of the image?

Answer 47

X-ray source should be positioned further away from the object (beam diverges less)

Question 48

What should the distance between source and film be?

Answer 48

Long

Question 49

What should distance between tooth and film be?

Answer 49

Short

Question 50

What is ‘cone cutting’ a result of?

Answer 50

Vertical angulation, when corners of the collimator have not been touching the guiding ring.

Question 51

What are the four main barriers to good positioning?

Answer 51

-mouth size -gag reflex -film size -digital sensor size and shape

Question 52

What are the 4 most common sizes of film/ PSP receptors?

Answer 52

0, 1, 2, 4

Question 53

What should the film size be for: Periapical radiograph of anterior adult teeth

Answer 53

0 or 1

Question 54

What should the film size be for: Periapical radiograph of anterior adult teeth using bisected angel technique

Answer 54

2

Question 55

What should the film size be for: Periapical radiograph of posterior adult teeth

Answer 55

2

Question 56

What should the film size be for: Bitewing radiograph of adult teeth

Answer 56

2

Question 57

What should the film size be for: Periapical radiograph of anterior children’s teeth

Answer 57

0

Question 58

What should the film size be for: Periapical radiograph of posterior children’s teeth (deciduous and permanent)

Answer 58

Deciduous = 0 Permanent = 2

Question 59

What should the film size be for: Bitewing radiograph of children over 10

Answer 59

2

Question 60

What should the film size be for: Bitewing radiograph of children under 10

Answer 60

0 or 1

Question 61

what is the “controlled area”?

Answer 61

The area in the immediate vicinity around the x-ray source

Question 62

What are the key four reasons to take bitewing radiographs?

Answer 62

To detect caries To monitor caries progression To assess periodontal status To assess existing restorations

Question 63

What happens in a caries risk assessment?

Answer 63

You perform images at regular intervals

Question 64

What happens in a caries risk assessment?

Answer 64

You perform images at regular intervals

Question 65

What are the advantages of horizontal bitewing over vertical?

Answer 65

Usually only two images taken whereas verticals require 4 images to be taken

Question 66

What is the advantage of vertical bitewings?

Answer 66

They demonstrate more of the roots

Question 67

In a horizontal bitewing, where should the centre of the bite block be placed so to cover the whole region of interest?

Answer 67

On the centre of the 6

Question 68

When would you pick a vertical bitewing over a horizontal bitewing?

Answer 68

When you need to see more of the root and supporting bone

Question 69

What are the positioning requirements for bitewings?

Answer 69

Film and object parallel Film close to object X-ray beam perpendicular to object and film

Question 70

How do we achieve good positioning?

Answer 70

By always using a holder

Question 71

what could be used as an alternative to film holder if patient cannot tolerate it?

Answer 71

Paper tab

Question 72

What does use of a guiding ring ensure?

Answer 72

That the x-ray beam is certain to hit the centre of the receptor

Question 73

When may horizontal overlap of teeth be difficult to avoid?

Answer 73

If there is crowding or tilting of teeth

Question 74

When would horizontal overlap of teeth be deemed acceptable?

Answer 74

If less than half of enamel is superimposed

Question 75

What are the two problems associated with vertical angulation of x-ray beam to receptor?

Answer 75

Upper bone levels will be projected off the receptor Resultant distortion of the teeth has caused separation of the cusps

Question 76

On a bitewing, where does the ‘dot’ on the receptor go?

Answer 76

Always to the palate

Question 77

If a child refuses to cooperate with bitewings what is the alternative?

Answer 77

Lateral oblique mandible images

Question 78

what can reduce the dose of radiation to patients by up to 50%?

Answer 78

Use of rectangular collimation

Question 79

Why is legislation for radiology necessary?

Answer 79

Helps to minimise risks from radiation exposure