Exposure Factors, Patient Exposure and Dose

Question 1

4 prime exposure factors

Answer 1

kVp
mA
time
distance

Question 2

increasing kVp will create a:

Answer 2

higher quality and more penetrating beam

Question 3

kVp also leads to a greater number of:

Answer 3

photons created at the anode target

Question 4

Increasing kVp by a factor of 2 does what to beam intensity?

Answer 4

increase by 4x

Question 5

increasing kVp increases:

Answer 5

patient dose

Question 6

increasing kVp will cause an increase in higher energy photons therefore:

Answer 6

decreasing image contrast

Question 7

a 15% increase in kVp:

Answer 7

will double IR exposure

Question 8

2 reasons why you double IR exposure when increasing kVp by 15%

Answer 8

increased number of photons created

increased number of photons penetrating the patient and reaching IR

(vice versa)

Question 9

a 15% increase in kVp is = to:

Answer 9

doubling the mAs

Question 10

a 15% decrease in kVp is = to:

Answer 10

halving the mAs

Question 11

when dealing with underexposure:

Answer 11

only change the kVp

Question 12

to increase exposure to IR, multiply kVp by

Answer 12

1.15

Question 13

to decrease exposure to IR, multiply kVp by

Answer 13

0.85

Question 14

increasing kVp by 15% and reducing mAs by 50% will reduce patient dose on average by:

Answer 14

20%

Question 15

increasing kVp by 15% ALONE will increase patient dose by:

Answer 15

30%

Question 16

beam intensity:

Answer 16

measurement of the concentration of photons in primary beam

Question 17

factors that affect beam intensity

Answer 17

mA
exposure time
kVp
distance
target material
target angle
generator type
filtration

Question 18

x-ray intensity and exposure will decrease as distance from the tube ________.

Answer 18

increases

Question 19

x-ray intensity and IR exposure will increase as distance from the tube ________.

Answer 19

decreases

Question 20

Doubling the distance between the x-ray tube and the IR does what to beam intensity at the IR?

Answer 20

4x decrease (divide intensity by 4)

Question 21

inverse square law:

Answer 21

I1/I2 =(D2/D1)^2

Question 22

increasing distance (SID) requires that the mAs be _________ to maintain exposure to IR

Answer 22

increased

Question 23

decreasing SID requires a _________ in the mAs to maintain exposure to IR

Answer 23

decrease

Question 24

mAs/distance formula

Answer 24

mAs1/mAs2=(D1/D2)^2

Question 25

In order to maintain optimal image receptor exposure, what adjustment to mAs must be made when increasing kVp from 80-92?

Answer 25

half the mAs

Question 26

how does mAs affect the primary beam?

Answer 26

increasing mAs will create a bigger beam

Question 27

how does filtration affect the primary beam?

Answer 27

higher filtration will create a harder average beam

low contrast, longer gray-scale