Chapter 8 Notes Flashcards

1
Q

x-ray photons are produced when

A

high-speed electrons from the cathode strike an anode target

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2
Q

the greater the mass or speed of the incident electrons

A

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

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3
Q

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

A

bremsstrahlung (brems) and characteristic interactions

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4
Q

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

A

less than 1%

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5
Q

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

A

99%

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6
Q

brems interactions occur when

A

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

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7
Q

the photon energy from a brems interaction is

A

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

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8
Q

characteristic interactions occur when

A

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

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9
Q

the photon energy of a characteristic interaction is

A

difference between the binding energy of the outer and inner shells

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10
Q

most photons are produced by what interaction

A

bremsstrahlung interactions

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11
Q

an x-ray emission spectrum graph illustrates what

A

relationship between the two target interactions within the primary beam

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12
Q

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

A

30-40%

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13
Q

changing kVp changes what

A

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

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14
Q

bremsstrahlung makes up what percent of diagnostic x-rays

A

> 90%

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15
Q

the closer the incident electron gets to the nucleus

A

the more it brakes and changes direction

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16
Q

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

A

photon energy (keV)

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17
Q

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

A

intensity (number of photons)

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18
Q

bremsstrahlung radiation produces a _____ spectrum

A

continuous

19
Q

kVp is

A

peak voltage applied to the x-ray tube

20
Q

keV is

A

unit used to measure the energy of x-ray photons

21
Q

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

A

69.53 keV

22
Q

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

A

70 kVp or higher

23
Q

beam quality

A

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

24
Q

beam quality is controlled by what

A

the kVp setting

25
Q

beam quantity

A

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

26
Q

what controls beam quantity

A

mA

27
Q

increasing mAs or kVp does what to IR exposure

A

increases it

28
Q

increasing distance or filtration does what to IR exposure

A

decreases it

29
Q

what target material do mammographic tubes use

A

molybdenum

30
Q

changing the kVp does not change the energy of

A

the characteristic x-rays

31
Q

as kVp increases

A

so does average energy

32
Q

as mA is doubled

A

the energy doubles

33
Q

as filtration is increased

A

the x-ray intensity decreases, but effective energy increases

34
Q

as the pulse phase increases

A

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

35
Q

increasing kVp does what to the graph

A

graph shifts to the right and up

36
Q

increasing mA does what to the graph

A

graph shifts up

37
Q

increasing filtration does what to the graph

A

graph shifts to the right and down

38
Q

improving the generator does what to the graph

A

graph shifts to the right and up

39
Q

as current (mAs) is increased

A

quantity is increased

40
Q

as voltage (kVp) is increased

A

quantity and quality increase

41
Q

as filtration is increased

A

quantity decreases, but quality increases

42
Q

as target atomic number increases

A

quantity and quality increase

43
Q

as voltage ripple increases

A

quantity and quality decrease