Ch. 7 X-ray production

Question 1

Kinetic energy is…

Answer 1

energy in motion

Question 2

Objects in motion have kinetic energy proportional to their…

Answer 2

mass and to the square of their velocity

Question 3

KE =

Answer 3

1/2 mv^2 (m= mass; v = velocity)

Question 4

all electrons have the same…

Answer 4

mass

Question 5

In an xray tube the projectile is the…

Answer 5

electron

Question 6

electron kinetic energy is increased how?

Answer 6

by raising the kVp

Question 7

When electron kinetic energy is increased what happens/

Answer 7

both the intensity (quantity) and energy (quality) of the xray beam are increased

Question 8

What is the distance of the filament to the xray tube target?

Answer 8

about 1 cm

Question 9

How fast are the electrons moving from the time it leaves the filament to the time it hits the target?

Answer 9

almost half the speed of light

Question 10

What are projectile electrons?

Answer 10

electrons traveling from cathode to anode

Question 11

What happens when projectile electrons hit the heavy metal atoms of the xray tube target?

Answer 11

They transfer their kinetic energy to the target atoms

Question 12

What do the projectile electrons interact with?

Answer 12

orbital electrons or the nuclear field of target atoms.

Question 13

What is the result of the interactions between the projectile electrons and orbital electrons?

Answer 13

a conversion of electron kinetic energy into thermal energy (heat) and electromagnetic energy in the form of infrared radiation and xrays.

Question 14

How much of the projectile electron kinetic energy is used for the production of xrays?

Answer 14

only 1%

Question 15

doubling the xray tube current doubles what?

Answer 15

it doubles the heat produced

Question 16

Heat production increases directly with…

Answer 16

increasing kVp

Question 17

The efficiency of xray production increases with…

Answer 17

increasing kVp

Question 18

When are characteristic xrays produced?

Answer 18

When a projectile electron interacts with an inner shell electron of the target atom rather than with an outer shell electron.

Question 19

When the interaction is sufficiently violent to ionize the target atom through total removal of an inner shell electron what happens?

Answer 19

characteristic xrays

Question 20

Characteristic xrays are emitted when an ____ electron fills and _____ void.

Answer 20

outer shell; inner shell

Question 21

The transition of an orbital electron from an outer shell to an inner shell is accompanied by…

Answer 21

the emission of an xray

Question 22

The energy of an xray is equal to…

Answer 22

the difference in the binding energies of the orbital electrons involved.

Question 23

The energy from M-K, N-K, O-K, and P-K can be…

Answer 23

calculated

Question 24

When are characteristic x-rays produced?

Answer 24

when the target atom is ionized by removal of electrons from shells other than the K shell.

Question 25

Only the K-characteristic x-rays of ____ are useful for imaging.

Answer 25

tungsten

Question 26

Characteristic x-rays can only be produced at specific...

Answer 26

energies equal to the differences in electron-binding energies for the various electron transitions.

Question 27

Why is characteristic x-ray production called characteristic?

Answer 27

Because it is characteristic of the target element.

Question 28

The effective energy of characteristic x-rays increases with...

Answer 28

increasing atomic number of the target element.

Question 29

The production of hea and characteristic x-rays involves interactions between...

Answer 29

the projectile and the electrons of x-ray tube target atoms.

Question 30

Describe a bremsstrahlung interaction.

Answer 30

Bremsstrahlung x-rays are produced when a projectile electron is slowed by the nuclear field of a target atom nucleus.

Question 31

What does the word bremsstrahlung mean?

Answer 31

it is a german word meaning slowed down radiation

Question 32

Bremsstrahlung x-rays can be considered radiation that results from...

Answer 32

the braking of projectile electrons by the nucleus.

Question 33

A projectile electron can lose any amount of its kinetic energy in an interaction with the nucleus of a target atom and the bremsstrahlung x-ray associated with the loss can take on what?

Answer 33

the corresponding values

Question 34

How does a low energy brems x-ray result?

Answer 34

When the projectile electron is barely influenced by the nucleus.

Question 35

How does a high energy brems x-ray result?

Answer 35

when the projectile electron loses all its kinetic energy and simply drifts away from the nucleus.

Question 36

What kind of brems x-rays are most frequent?

Answer 36

The ones between low and highest energy.

Question 37

In diagnostic range, which type of x-rays are the most common?

Answer 37

brems

Question 38

What does the energy of the electron have to be in order to create at brems x-ray?

Answer 38

it can be at any energy

Question 39

A discrete spectrum contains....and a continuous spectrum contains....

Answer 39

only specific values....all possible values

Question 40

What kind of x-ray spectrum do characteristic x-rays have?

Answer 40

the energies of characteristic x-rays are fixed so the emission spectrum would be discrete

Question 41

The Brem x-ray emission spectrum extends from ___ to ____

Answer 41

0 to maximum projectile electron energy

Question 42

The highest number of brem x-rays only have about ____ of the maximum energy of the beam.

Answer 42

1/3

Question 43

Brem x-rays have a ___ of energies and form a _____ emission spectrum.

Answer 43

range; continuous

Question 44

With brems, the number of x-rays emitted ____ at very low energies.

Answer 44

decreases

Question 45

The energy of an x-ray is equal to..

Answer 45

the product of its frequency and Planck's constant

Question 46

x-ray energy is inversely proportional to what?

Answer 46

its wavelength

Question 47

As x-ray wavelength increases, x-ray energy....

Answer 47

decreases

Question 48

If the curve of an emission spectrum goes to the right what does that indicate?

Answer 48

he higher the effective energy or QUALITY of the x-ray beam

Question 49

The larger the area under the curve of an emission spectrum indicates...

Answer 49

higher x-ray intensity or QUANTITY

Question 50

A change in mA or mAs results in what kind of change in the emission spectrum?

Answer 50

a change in the amplitude but not the position

Question 51

As kVp is raised, how does the emission spectrum change? (factor)

Answer 51

the area under the curve increases to an area approximating the square of the factor by which kVp was increased.

Question 52

When kVp changes, how does the appearance of the spectrum change?

Answer 52

in amplitude and position

Question 53

What is the % of change in kVp that needs to happen to be equal to doubling mAs?

Answer 53

15%....15/50 rule

Question 54

What affect does adding filtration have on the beam?

Answer 54

It reduces intensity while increasing the average energy.

Question 55

What is a word used when adding filtration to a beam?

Answer 55

hardening

Question 56

Does the atomic number of the target affect the quantity and quality of the beam? How?

Answer 56

yes as the atomic number of the target material increases, the efficiency of the production of bremsstrahlung radiation increases, and high energy x-rays increases in number to a greater extent than low energy x-rays.

Question 57

What are the 5 voltage waveforms?

Answer 57

half wave rectified, full wave rectified, 3 phase/6 pulse, 3 phase/12 pulse, and high frequency

Question 58

What is the relationship between full wave and half wave rectified?

Answer 58

They are the same except for the frequency of x-ray pulse repetition.

Question 59

What is the relationship between 3 phase/6 pulse and 3 phase/12 pulse?

Answer 59

There is reduced ripple with 12 pulse generation compared with 6 pulse generation

Question 60

What produce the lowest voltage ripple of all high voltage generators?

Answer 60

high-frequency generators

Question 61

Because of reduced ripple, operation with 3 phase power or high frequency is equivalent to ....

Answer 61

about 12% increase in kVp, or almost a doubling of mAs over single phase power.