Projection Geometry: Intraoral Radiographic Technique- 9/19- DONE over powerpoint but add study guide stuff

Question 1

Geometric characteristics include: (3)

Answer 1

1. image sharpness
2. image magnification
3. image shape distortion

Question 2

Fuzzy, unsharp margin of radiographic image:

Answer 2

unsharpness

Question 3

Penumbra:

Answer 3

unsharp margin of the image

Question 4

umbra:

Answer 4

shadow

Question 5

We want to minimize ____ or maximize ____

Answer 5

unsharpness; sharpness

Question 6

What are the 3 rules to maximize sharpness?

Answer 6

1. Radiation source should be as small as possible
2. Source- to-object distance should be as long as possible
3. Object-to-receptor distance should be as short as possible

Question 7

What is the benefit of having a smaller focal spot?

Answer 7

Fewer x-ray photons that interact with the edge of the object leading to a sharper image

Question 8

The source is the ____, when referring to “source-to-object”

Answer 8

focal spot

Question 9

The closer the object is tot he focal spot, the more___ the x-ray photons are that are going to interact with the edge of the tooth

Answer 9

divergent

Question 10

The shorter the source-to-object distance, the greater the ___ meaning ____

Answer 10

penumbra; the greater the unsharpness of the margin

Question 11

How do we control the course-to-object distance?

Answer 11

by the length of the cone

Question 12

We prefer to use a ___ cone than a ___ cone because the x-rays that interact with the object are more parallel which will maximize sharpness.

Answer 12

longer cone; shorter cone

Question 13

You want the object or tooth to be as close to the ____ as possible

Answer 13

image receptor

Question 14

We have greater ____ with longer object-to-receptor distance

Answer 14

Penumbra

Question 15

The equal enlargement of the object:

Answer 15

magnification

Question 16

2 rules to minimize magnification include:

Answer 16

1. source-to-object distance should be as long as possible
2. Object-to-receptor distance should be as short as possible

Question 17

Enlargement of radiographic image, compared to actual size of the object:

Answer 17

magnification

Question 18

With magnification, the image shows the:

Answer 18

true shape of the object

Question 19

If the distance of the source to the tooth is short, then the x-rays that interact with the tooth will be fairly ____ leading to ____.

Answer 19

divergent; greater magnification

Question 20

If the distance of the source to the tooth is longer, then the x-rays in the beam that interact with the tooth will be more ____ leading to less ____.

Answer 20

parallel; magnification

Question 21

Unequal enlargement:

Answer 21

distortion

Question 22

Variation from tube shape of object:

Answer 22

distortion

Question 23

Shape distortion has more to do with ___ than ___.

Answer 23

angles; distances

Question 24

Unequal magnification of parts of an object:

Answer 24

distortion

Question 25

Distortion can be caused by:

Answer 25

improper alignment of receptor, object, or beam

Question 26

What are the rules for minimizing shape distortion? (2)

Answer 26

1. object and receptor should be parallel 2. beam should be perpendicular to object & receptor

Question 27

CR in the diagrams stands for:

Answer 27

central ray

Question 28

The radiographic image of the object is shorter than the object itself

Answer 28

foreshortening

Question 29

Tooth is not parallel to the receptor and beam directed perpendicular can lead to what type of shape distortion? (2)

Answer 29

foreshortening & elongation

Question 30

The radiographic image is longer than the object itself:

Answer 30

elongation

Question 31

5 rules for accurate image formation:

Answer 31

1. focal spot as small as possible 2. source-object distance as long as possible (cone length) 3. Object-receptor distance as short as possible (Film placement) 4. object parallel to receptor (image receptor placement) 5. beam perpindicular to object and receptor

Question 32

Projection techniques for periodical radiography include: (2)

Answer 32

1. paralleling technique: use long cone 2. bisecting angle technique: use long or short cone

Question 33

What are the two steps for the paralleling technique?

Answer 33

1. receptor parallel to tooth 2. beam perpendicular to tooth

Question 34

In the paralleling technique when having the receptor parallel to the tooth, we want ____ object-receptor distance, and ___ source-receptor distance

Answer 34

increased; increased

Question 35

What balances out the increased object-receptor distance when using the paralleling technique?

Answer 35

increased source-to-receptor distance (minimizing unsharpness & magnification)

Question 36

What type of cone is used to increase the source-to-receptor distance using the paralleling technique?

Answer 36

Long cone

Question 37

Getting the image receptor parallel to the teeth allows for correct ____ angulation

Answer 37

vertical

Question 38

If you are using the XCP correctly and you line up the beam with the cone, the x-ray beam will image:

Answer 38

entire area of interest (no cone cuts)

Question 39

Cone cut shows up on the radiograph as:

Answer 39

white area

Question 40

Getting a cone cut means you automatically have to retake the image (T/F)

Answer 40

False; as long as you obtain the area of interest

Question 41

In a PA radiograph, we want ___ mm of bone around the apices

Answer 41

2-3mm (pretty sure)

Question 42

If the contacts are open in the areas of interest this tells us that ____ angulation was correct

Answer 42

horizontal

Question 43

The ____ technique is the preferred technique but the ____ technique may be used if the first choice technique does not work.

Answer 43

paralleling technique; bisecting angle technique

Question 44

With he bisecting angle technique, you are not trying to get the image receptor parallel to the tooth, you are just trying to get it ___ to the tooth

Answer 44

close

Question 45

The bisecting angle technique is based on:

Answer 45

The rule of isometry

Question 46

In the bisecting angle technique, if two triangles have two equal angles and a common side, then:

Answer 46

the two triangles are equal

Question 47

The bisecting angle technique states that the angle formed by the plane of the tooth and plane of receptor is bisected and the beam is directed ____ to the bisecting line

Answer 47

perpendicular

Question 48

The ____ technique has more limitations than the ____ technique

Answer 48

bisecting angle technique; paralleling technique

Question 49

Why is the paralleling technique preferred technique over the bisecting angle technique?

Answer 49

a little more distortion with the bisecting angle technique

Question 50

The bitewing is used to see:

Answer 50

crowns, inter proximal bone levels, alveolar bone support, caries, periodontal condition, calculus, crown margins

Question 51

Bitewings are not used to view:

Answer 51

periapical regions of the tooth

Question 52

Bitewing technique: The ___ angle is more of a challenge than the ____ angle.

Answer 52

horizontal; vertical

Question 53

In the bitewing technique, you'd like to us a ____ vertical angulation

Answer 53

slightly positive (+5 to10 degrees depending on location)

Question 54

If the horizontal angulation is incorrect in the bitewing technique, then the image will display:

Answer 54

overlapping contacts

Question 55

____ includes periapical and bitewing radiographs showing all teeth:

Answer 55

full mouth series

Question 56

When viewing radiographs, what's on the providers right is actually the patients:

Answer 56

left

Question 57

Radiographic localization includes: (2)

Answer 57

1. right angle method 2. tube shift method (SLOB)

Question 58

The right angle method states that:

Answer 58

if you take radiographs at right angles to each other of the areas of interest you can localize the area in question

Question 59

If you take radiographs at right angles to each other of the areas of interest, you can localize the area in question:

Answer 59

right angle methodT

Question 60

Same Lingual Opposite Buccal:

Answer 60

SLOB rule

Question 61

Tube shift method may also be called:

Answer 61

SLOB rule

Question 62

In the tube shift method, you will take a second radiograph of the same area but alter the ____.

Answer 62

horizontal angulation

Question 63

In the tube shift method, if you take the first radiograph straight on, you may take the second radiograph ____ (for example)

Answer 63

mesially

Question 64

If the object moves in the same direction as what you moved the tubehead, then the object is ____ to the reference point (SAME)

Answer 64

lingual

Question 65

If you take a straight on view of the premolars and you see the lesion apical to the apex, you rotate the tube head mesially, and the the lesion now moved distal to the apex of the tooth. This is the example of:

Answer 65

Opposite- buccal

Question 66

The tube shift method technique, you can move the tube ___ or ____ on the second image.

Answer 66

mesially or distally (potentially even vertically)

Question 67

First radiograph: supernumerary tooth overlapping the mesial of the root of the second molar Move tube mesially Second radiograph: the supernumerary tooth now does not overlap the mesial root of the second molar (shifted slightly mesial), This means the lesion is:

Answer 67

lingual

Question 68

SLOB stands for:

Answer 68

same lingual opposite buccal

Question 69

shadow; the image of the object we receive

Answer 69

umbra

Question 70

Edge gradient; the unsharp area; area around the margins of the object

Answer 70

penumbra

Question 71

What do we try to minimize when taking radiographs?

Answer 71

penumbra

Question 72

How do we minimize penumbra?

Answer 72

by having an increased source to object ratio

Question 73

3 factors that affect the