Chapter 4

Question 1

We owe it to our patients to…

Answer 1

Patients agree to be exposed to ionizing radiation

Ethical responsibility to produce the highest quality radiographs

to produce the radiographs at the lowest possible radiation dose

Question 2

3 requirements for acceptable quality

Answer 2

1. Accurate
   
   • close to natural shape and size
   • minimal Distortion and superimposition
2. The complete area has to be imaged
   
   • 2mm from the apex
     - Must show proper density, contact, and definition
3. Free from errors

Question 3

Radiolucent

Answer 3

See-through, less dense, shows up dark or black

ex, pulp chambers, maxillary sinus, or gum line

Question 4

Radiopaque

Answer 4

Shows up bright or white

Ex, bones, restorations, enamel

Question 5

Density

Answer 5

• The degree of darkness
• Dark image = more dense
• Increased when mA or exposure is increased
• Proper amount of density = quality, allows us to view radiolucent, radiopaque, and gray areas distinctly

Question 6

Undiagnostic

Answer 6

Too dark or light, teeth, and supporting structures can’t be visually separated

Question 7

Traditional film

Answer 7

X-rays strike crystals in film emulsion, and processing causes crystals to darken

Question 8

Digital image

Answer 8

X-rays strike sensor and sensitive pixels, and processing by computer software darkens the pixels

Question 9

Contrast

Answer 9

The difference between black and white

• a diagnostic radiograph shows dark, light, and gray areas

Short scale contrast is good

Question 10

Short scale contrast

Answer 10

Very few shades of gray, mainly black and white

Question 11

Long scale contrast

Answer 11

Many shades of gray

Question 12

Sharpness

Answer 12

The detail and clarity of the outline

Question 13

factors effecting sharpness

Answer 13

1. patient movement
   
   • Causes Penumbra- blurriness of edges
2. Receptor (sensor) movement
3. Tubehead too far away from the face

Question 14

Quality images

Answer 14

1. A long target-to-object distance
   
   • Keeps the primary beam focused longer
2. Short Object to sensor distance
3. Sensor and the long axis of the tooth parallel
4. Central ray must be perpendicular to the tooth

Question 15

Factors the affect radiographic images

Answer 15

1. contrast
2. Sharpness
3. magnification
4. Distortion

Question 16

How does contrast affect images

Answer 16

• Visible differences between densities on radiograph
  
  • Higher kVp= lower contrast (more shades of gray)
  • Lower kVp= higher contrast (more blacks and whites)
• Scatter radiation reduces contrast
  
  • Collimator controls scatter
    -Over or under exposure will result in poor contrast

Question 17

How does sharpness affect images

Answer 17

clarity of the outline of the structure
- Smaller the focal spot (tungsten target), the sharper the image will be

Question 18

How does magnification effect radiographs

Answer 18

influenced by target-object distance and object-sensor distance.

• Long target-object and short object- sensor, reduces magnification

Question 19

How does distortion effect images

Answer 19

-unequal magnifications of different parts of an object

results when the image receptor and object are not parallel and or when the dental ray is not perpendicular to the image receptor and object

Question 20

Inverse square law

Answer 20

The further the distance from the source the less intense the beam is

Question 21

Factors affecting density

Answer 21

Increase mA, kVp, or exposure the image darkens

Decrease mA, kVp, or exposure makes the image lighter

Question 22

Target to sensor distance

Answer 22

increase distance- decreases the magnification

Decreases distance- increases the magnification

Question 23

Object to sensor distance

Answer 23

Increase distance- increases magnification

Decreases distance- decrease the magnification