Projection Geometry: Intraoral Radiographic technique (Exam 2)

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

The unsharp margin of the image

Question 4

Umbra:

Answer 4

Shadow

Question 5

We want to minimize the _____ or maximize the ____

Answer 5

unsharpness; sharpness

Question 6

What are the three 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

When we say the Source-to-object distance should be as long as possible, what is the source?

Answer 8

The focal spot

Question 9

The closer the object is to the focal spot, the more _____ the X-ray photons are that are going to interact with the edges 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 source-to-object distance?

Answer 11

By the length of the cone (longer cones better)

(its not exactly synonymous to source-to-object distance but we think of it as this way)

Question 12

The X-rays beams will be more parallel to the object if we use a:

Answer 12

Longer cone

Question 13

We have greater _____ with a longer object-to-receptor distance

Answer 13

Penumbra

Question 14

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

Answer 14

Image receptor

Question 15

The equal enlargement of the object:

Answer 15

Magnification

Question 16

Two rules to minimize magnification:

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 object:

Answer 17

Magnification

Question 18

If the distance from the source to the tooth is short then the X-rays that interact with the tooth are still going to be fairly _____ leading to ____

Answer 18

Divergent; greater magnification

Question 19

If the distance form the source to the tooth is longer than the X-ray beam that interacts with the tooth is going to be fairly ____ leading to ____

Answer 19

Parallel; less magnification

Question 20

Shape distortion has more to do with ____ than ____

Answer 20

Angles; distance

Question 21

Unequal enlargement:

Answer 21

Distortion

Question 22

not only is the object larger but the shape is inaccurate:

Answer 22

Distortion

Question 23

Variation from true shape of object; unequal magnification of parts of object:

Answer 23

Distortion

Question 24

Distortion can be caued by:

Answer 24

Improper alignment of receptor, object or beam

Question 25

What are the rules for minimizing distortion?

Answer 25

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

Question 26

CR in the diagrams stands for:

Answer 26

Central ray

Question 27

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

Answer 27

Foreshortening

Question 28

Tooth is not parallel to receptor and beam directed perpendicular can lead to what type of distortion?

Answer 28

Forshortening & elongation

Question 29

The radiographic image is longer than the object itself:

Answer 29

Elongation

Question 30

Tooth not parallel to receptor, and beam directed perpendicular to tooth:

Answer 30

Elongation

Question 31

Five rules for accurate image formation:

Answer 31

1. focal spot as small as possible 2. source-object distance as long as possible 3. object-receptor distance as short as possible 4. object parallel to receptor 5. beam perpendicular to object and receptor

Question 32

Projection techniques for periapical radiography: (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 to the paralleling technique?

Answer 33

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

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're using the XCP correctly and you line up the beam with the cone, the X-ray beam will image:

Answer 38

the entire area of interest (no cone cuts)

Question 39

Getting a cone cut autonatically means you have to retake image (T/F):

Answer 39

False (as long as you obtain the area of interest you don't have to retake)

Question 40

Cone cuts show up on radiographs as:

Answer 40

White areas

Question 41

If the contacts are open in the area of interest this tells us the _____ angulation is correct

Answer 41

horizontal

Question 42

The _____ is the preferred technique but the ___ technique may be used if the first choice technique does not work

Answer 42

Paralleling technique; bisecting angle technique

Question 43

With the bisecting angle technique, you are not trying to get the image receptor parallel to the tooth, but rather just trying to get it _____ to the tooth

Answer 43

Close

Question 44

The bisecting angle technique is based on:

Answer 44

The rule of isometry

Question 45

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

Answer 45

The two triangles are equal

Question 46

According to the bisecting angle technique if you direct the X-ray being perpendicular to the bisecting line that you estimated when lining things up you should:

Answer 46

Get a pretty good image

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

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

Answer 48

a little more distortion with the bisecting angle technique

Question 49

preferred image for checking bone level:

Answer 49

Bitewing

Question 50

The ___ technique has more limitations than the ____ technique

Answer 50

Bisecting angle technique; paralleling technique

Question 51

The bitewing is used to see:

Answer 51

Crowns, interproximal bone levels, alveolar bone support, caries, periodontal condition, calculus and crown margins

Question 52

Bitewings are not used to view:

Answer 52

Periapical regions of the tooth

Question 53

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

Answer 53

Horizontal; vertical

Question 54

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

Answer 54

slightly positive (+5 to 10 degrees depending on location)

Question 55

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

Answer 55

Overlapping contacts

Question 56

____ includes periapical and bitewing radiographs showing all teeth

Answer 56

Full mouth series

Question 57

When viewing radiographs, whats on the providers right is actually the patients:

Answer 57

Left

Question 58

Radiographic localization includes: (2)

Answer 58

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

Question 59

States if you take radiographs at right angles to eachother of the areas of interest you can localize the area in question:

Answer 59

Right angle method

Question 60

The right angle method states:

Answer 60

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

Question 61

SLOB stands for:

Answer 61

Same Lingual Opposite Buccal

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 or distally (or even vertically)

Question 64

If the object moves in the same diredction as you move the tube head, than the object is ____ to the reference point (same)

Answer 64

Lingual

Question 65

When using the slob rule, if the object moves in the opposite direction as the tube head was moved, than the object is ____ to the reference point (opposite)

Answer 65

Buccal

Question 66

First radiograph: supernumerary tooth overlapping mesial of the root Using SLOB method you move tube mesially in second radiograph Second radiograph: the supernumerary tooth now does not overlap the mesial root of the second molar (shifter slightly mesial) This means the lesion is:

Answer 66

Lingual

Question 67

The tube shift method for radiographic localization may also be referred to as:

Answer 67

SLOB

Question 68

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

Answer 68

Penumbra

Question 69

What do we try to minimize when taking radiographs?

Answer 69

Penumbra

Question 70

How do we minimize penumbra?

Answer 70

By having an increased source to object ratio

Question 71

Three factors that affect the quality of a ra