Chapter 8 Notes

Question 1

x-ray photons are produced when

Answer 1

high-speed electrons from the cathode strike an anode target

Question 2

the greater the mass or speed of the incident electrons

Answer 2

the greater the quality (energy) and quantity (number) of photons produced

Question 3

what are the two target interactions that produce x-ray photons

Answer 3

bremsstrahlung (brems) and characteristic interactions

Question 4

what percent of the total kinetic energy of the incident electrons produces interactions

Answer 4

less than 1%

Question 5

what percent of the kinetic energy of the incident electrons is converted to heat

Answer 5

99%

Question 6

brems interactions occur when

Answer 6

the incident electron interacts with the force field of the nucleus; causes electron to brake and then diverts its course

Question 7

the photon energy from a brems interaction is

Answer 7

the difference between the entering and exiting kinetic energy of the electron

Question 8

characteristic interactions occur when

Answer 8

the incident electron interacts with an inner-shell electron; an electron hole is created, making the atom unstable; causes cascade effect

Question 9

the photon energy of a characteristic interaction is

Answer 9

difference between the binding energy of the outer and inner shells

Question 10

most photons are produced by what interaction

Answer 10

bremsstrahlung interactions

Question 11

an x-ray emission spectrum graph illustrates what

Answer 11

relationship between the two target interactions within the primary beam

Question 12

average primary beam photon has a keV energy of only about _____ percent of the kVp

Answer 12

30-40%

Question 13

changing kVp changes what

Answer 13

the quality (energy) of electrons striking the target; changes the number of higher-energy photons and the amplitude of the emission spectrum graph

Question 14

bremsstrahlung makes up what percent of diagnostic x-rays

Answer 14

> 90%

Question 15

the closer the incident electron gets to the nucleus

Answer 15

the more it brakes and changes direction

Question 16

the x-axis on the x-ray spectrum represents what

Answer 16

photon energy (keV)

Question 17

the y-axis on the x-ray spectrum represents what

Answer 17

intensity (number of photons)

Question 18

bremsstrahlung radiation produces a _____ spectrum

Answer 18

continuous

Question 19

kVp is

Answer 19

peak voltage applied to the x-ray tube

Question 20

keV is

Answer 20

unit used to measure the energy of x-ray photons

Question 21

what is the binding energy of the K-shell in tungsten

Answer 21

69.53 keV

Question 22

must select what kVp for characteristic radiation to be produced with tungsten

Answer 22

70 kVp or higher

Question 23

beam quality

Answer 23

the penetrating ability of the x-ray beam (energy of the photons produced)

Question 24

beam quality is controlled by what

Answer 24

the kVp setting

Question 25

beam quantity

Answer 25

the x-ray beam's intensity (number of photons actually produced)

Question 26

what controls beam quantity

Answer 26

mA

Question 27

increasing mAs or kVp does what to IR exposure

Answer 27

increases it

Question 28

increasing distance or filtration does what to IR exposure

Answer 28

decreases it

Question 29

what target material do mammographic tubes use

Answer 29

molybdenum

Question 30

changing the kVp does not change the energy of

Answer 30

the characteristic x-rays

Question 31

as kVp increases

Answer 31

so does average energy

Question 32

as mA is doubled

Answer 32

the energy doubles

Question 33

as filtration is increased

Answer 33

the x-ray intensity decreases, but effective energy increases

Question 34

as the pulse phase increases

Answer 34

the number of x-rays and x-ray energy increases

Question 35

increasing kVp does what to the graph

Answer 35

graph shifts to the right and up

Question 36

increasing mA does what to the graph

Answer 36

graph shifts up

Question 37

increasing filtration does what to the graph

Answer 37

graph shifts to the right and down

Question 38

improving the generator does what to the graph

Answer 38

graph shifts to the right and up

Question 39

as current (mAs) is increased

Answer 39

quantity is increased

Question 40

as voltage (kVp) is increased

Answer 40

quantity and quality increase

Question 41

as filtration is increased

Answer 41

quantity decreases, but quality increases

Question 42

as target atomic number increases

Answer 42

quantity and quality increase

Question 43

as voltage ripple increases

Answer 43

quantity and quality decrease