Factors Affecting X-ray Beam Intensity (Lec 5)

Question 1

Total amount of energy contained in the x-ray beam:

Answer 1

intensity

Question 2

intensity =

Answer 2

quantity x quality

Question 3

the average energy in the x-ray beam:

Answer 3

quality

Question 4

quality is related to:

Answer 4

tube voltage (kVp)

Question 5

according to quality, the x-ray beam is:

Answer 5

heterogeneous

Question 6

the number of photons in the x-ray beam:

Answer 6

quantity

Question 7

quantity is related to tube ____ and ___

Answer 7

current; exposure time (mAs)

Question 8

List the factors affecting intensity: (6)

Answer 8

1. kilovoltage
2. milliamperage
3. exposure time
4. filtration
5. collimation
6. source to film distance (inverse square law)

Question 9

The inverse square law describes:

Answer 9

Source to film distance (factor affecting intensity)

Question 10

As tube voltage increases:

1. the number of photons generated ____ (_____)
2. mean energy of photon _____ (_____)
3. maximum energy of photon _____

Answer 10

1. increases (increased quantity)
2. increases (increased quality)
3. increases

Question 11

As exposure time increases:

1. number of photons generated _____ (_____)
2. the mean energy of photons _____ (_____)
3. maximum energy of photons ______ (_____)

Answer 11

1. increases (increased quantity)
2. is unchanged (unchanged quality)
3. is unchanged (unchanged quality)

Question 12

As tube current (mA) increases:

1. number of photons generated ____ (____)
2. the mean energy of photons is _____ (____)
3. the maximum energy of photons _____ (____)

Answer 12

1. increases (increased quantity)
2. is unchanged (unchanged quality)
3. is unchanged (unchanged quality)

Question 13

selectively removes long wavelength (low energy) x-rays:

Answer 13

filtration

Question 14

-glass envelope
-immersion oil
-metal housing
-tube window

these are all considered:

Answer 14

Inherent filtration

Question 15

the aluminum discs are considered:

Answer 15

added filtration

Question 16

As filtration increases:

1. number of photons _____ (_____)
2. the mean energy of photons _____ (_____)
3. the maximum energy of photons ____

Answer 16

1. decreases (decreased quantity)
2. increases (increased quantity)
3. is unchanged

Question 17

Restricts the size and shape of the beam:

Answer 17

Collimation

Question 18

a method of calculating the new beam intensity when changing the source-to-receptor distance:

Answer 18

inverse square law

Question 19

according to the inverse square law:

if distance is doubled (8 to 16) = new intensity will be:

if distance is tripled (4 to 12) = new intensity will be:

if distance is halved (8 to 16) = new intensity will be:

Answer 19

1/4 (inverse of 2^2)

1/9 (inverse of 3^2)

4x (inverse of 1/2^2)

Question 20

With collimation:

1. number of photons _____
2. mean energy of photons _____
3. maximum energy of photons ____

Answer 20

1. decreases
2. is unchanged
3. is unchanged

Question 21

intensity of the beam varies inversely to:

Answer 21

the square of the source-to-receptor distance

Question 22

as source to receptor distance increases:

1. number of photons ____ (____)
2. mean energy of photons _____ (___)
3. maximum energy of photons ____

Answer 22

1. decreases (decreased quantity)
2. is unchanged (unchanged quality)
3. is unchanged

Question 23

Increasing the source to film distance by 2:

Answer 23

decreases photons by 1/4 (by 4)

Question 24

Which of the six factors affect the quantity of the x-ray beam?

1. tube voltage (kVp)
2. tube current (mA)
3. exposure time (s)
4. mAs
5. distance
6. filtration

Answer 24

all of them affect quantity

Question 25

Which of the six factors affect the quality of the x-ray beam?

1. tube voltage (kVp)
2. tube current (mA)
3. exposure time (s)
4. mAs
5. distance
6. filtration

Answer 25

Filtration & tube voltage (kVp)

Question 26

Density is altered by factors affecting the ____ of the beam

Answer 26

quantity

Question 27

Contrast is altered by factors affecting the ____ of the beam

Answer 27

quality

Question 28

amount of blackness of an image:

Answer 28

density

Question 29

Density is the amount of blackness in an image which is related to:

Answer 29

How many x-rays reach the receptor

Question 30

Density is primarily controlled by ____ and less so by ____

Answer 30

mAs (mA and exposure time); kVp

Question 31

Increasing the source-to-film distance will decrease _____ due to decreased number of photons

Answer 31

density

Question 32

Increasing the source-to-film distance has what effect on density?

Answer 32

Decreases density (due to decreased number of photons)

Question 33

mA and exposure time are inversely proportional describing:

Answer 33

mAs rule (density)

Question 34

if mA is increased, what must happen to exposure time to maintain the same density of the image?

Answer 34

exposure time must be decreased

Question 35

if mA is decreased, what must happen to exposure time to maintain the same density of the image?

Answer 35

exposure time must be increased

Question 36

the difference in densities between light and dark regions of a radiograph:

Answer 36

Contrast

Question 37

contrast is primarily controlled by the:

Answer 37

voltage

Question 38

-air
-bone
-metal
-tongue
-enamel

Put in order from lowest to highest contrast
(dark to light on radiograph)

Answer 38

1. air (darkest)
2. tongue
3. bone
4. enamel
5. metal (lightest)

Question 39

The short gray scale is involved in:

Answer 39

High contrast

Question 40

The long gray scale is involved in:

Answer 40

Low contrast

Question 41

High contrast (short gray scale) = ____ kVp

Answer 41

low kVp (long wavelengths, less penetrating)

Question 42

In the short gray scale (high contrast), density differences between adjacent areas are ____

____ shades of gray

Answer 42

greater; fewer

Question 43

Low contrast (long gray scale) = ___ kVp

Answer 43

high kVp (short wavelengths, more penetrating)

Question 44

In the long gray scale (low contast), density differences between adjacent areas are ___

___ shades of gray

Answer 44

more subtle; more

Question 45

Effect of kVp on contrast:

Low kVp = _____ contrast

High kVp= _____ contrast

Answer 45

high contrast (short gray scale)

low contrast (long gray scale)