Class Notes 10.06.08

Class notes 10.06.08

Distance – Effect on contrast SID – increase contrast will increase (short scale) SID – decrease contrast will decrease (long scale)

Image Image Low Contrast High Contrast Intensifying – effect on contrast Increasing the intensifying screen speed will increase the radiographic contrast, as compared to non-screen/ direct x-ray image. Grids – effect on contrast Increase with grid ratio will increase the radiographic contrast due to the greater absorption of the x-ray energy. Patient – effect on contrast Anatomic part thickness: More radiation is required to penetrate through the patient to the image receptor. KVp is adjusted based on patient thickness. Must use calipers to measure the anatomic part. Tissue Density Tooth Enamel Bone Cartilage Muscle Fluid filled air Fat Air Processing Radiographic contrast will decrease: 1. Increase developer time 2. Increase developer temperature 3. Increase in chemical concentration 4. Extraneous light fog 5. Increase in chemical fumes Contrast media High contrast/short scale Any type of contrast media will increase the contrast.

Radiopaque

Radiolucent

Class notes 10.06.08

mA

kV p

time

Dista nce 1

A 200

0.3

90

1

32 2

B 300

0.2 0.012 5

C 500

70

2

36 3

60

3

40 4

1 D 000

0.1

More Contrast = Answer is:

mA

0.3

44

Fast

kV p

Dista nce

Scre ens

90

0.2 0.012 5

4

32

70

3

36 2

60

2

40 1

1 D 000

0.1

Less Contrast = Answer is:

mA A 200

0.3

B 300 3

C 500 4

1 D 000

1

1

8:01 N ongrid

kV p

Dista nce

Scre ens

G rids 16:0 1 10:0 1

4

2

Fast

4

90

4

32 3

70 1

3

36 2

60 2

0.1

Par Rare Earth Detai l

44

3

0.2 0.012 5

3

50

4

2

1

4

OI D 18

2

SO D 14

T ota l 2

12 3

14

1

19

1

3

30

3

10

4

2

33

4

11

3

13 17 20

8:01 N ongrid

2

OI D 12

4

SO D 20

T ota l 4

21 3

22

3

14

3

3

28

2

12

2

4

30

1

14

3

16 15 12

A

time 1

4

3

50

3

C 500

Par Rare Earth Detai l

4

4

B 300

2

G rids 16:0 1 10:0 1

D

time

A 200

Scre ens

2

40 1

50

2

Par Rare Earth Detai l

1

44

4

1

3

Fast

G rids 16:0 1 10:0 1 8:01 N ongrid

2

OI D 11

4

SO D 21

T ota l 4

25 3

26

2

10

1

3

24

3

16

3

31

1

13

2

21 18 4

18

Class notes 10.06.08

More Density = Answer is:

mA

kV p

time 4

A 200

1

0.3 3

B 300 2

C 500

0.2 0.012 5

90

32

70 4

2

36 3

60

3

40 4

50

Scre ens 1

2

3

0.1

Dista nce 1

2

1

1 D 000

A

3

Par Rare Earth Detai l

4

44

1

4

2

Fast

G rids 16:0 1 10:0 1 8:01 N ongrid

4

OI D 9

2

SO D 23

T ota l 3

19 3

23

4

13

4

3

12

3

28

2

9

2

35

1

21 24 2

OID – Focal spot size – has no effect on density or contrast, but it does have on radiographic detail. SOD – increase SOD will increase density.

19