X Ray Production

Front 1

all target interactions occur with ____ to ____

target surface

Back 1

0.25 to 0.5 mm

Front 2

incident electrons transfer kinetic energy to outer shell electrons of the target atoms causes

Back 2

infrared radiation ( heat )

Front 3

as filament electrons enter the anode target

Back 3

most interact with outer shell electrons of the tungsten atoms

they do not transfer enough kinetic energy to ionize the atom

they excite

give off heat

Front 4

rhenium z #

Back 4

75

Front 5

tungsten and rhenium melting point

Back 5

3410

Front 6

mammo target material

Back 6

molybdenum

Front 7

brems is the german work for ___

Incident electron (filament electron) interacts with electrostatic force field of the

Back 7

braking

nucleus

Front 8

Mutual attraction

Back 8

slow electron

Front 9

Strong nuclear force

Back 9

keeps them apart and deflects incident electron

Front 10

Brems Interactions accounts for ______

Back 10

85 to 100 percent of beam

Front 11

Photon energy dependent on

Back 11

how close electron comes to nucleus

Front 12

As incident electrons get closer to the nucleus the following occurs

Back 12

Photon energy increases

Larger deflection of the incident electron

Front 13

With a tungsten target, most of the photons produced are brems for several reasons

Back 13

With characteristic interactions, only those involving the K shell are of sufficient energy to be useful. All others are too weak to contribute to the radiographic image and are typically filtered out

The filament electron is more likely to miss the orbital electrons of the target atom because they are in constant motion and the atom is mostly empty space.

Front 14

Characteristic interactions involve the following:

Back 14

filament electron (incident electron)

An orbital electron of a target atomMust be a K shell to contribute to the primary beam

Front 15

Incident electron interacts with K-shell electron and removes it from orbit

Back 15

Incident electron continues in slightly different direction

Front 16

Kinetic energy of the incident electron must overcome ________of the K shell

Back 16

binding energy

Front 17

Occurs in techniques using _____ or higher

Back 17

70kvp

Front 18

Characteristic cascade

Back 18

Hole in inner shell and must be filled by an electron from outer shell

Electron energy difference

Secondary photons produced

Front 19

Only electron that drops into______ will contribute to the beam

Back 19

k shell

Front 20

Energy of photon emitted =

Back 20

to the difference of the two shells’ binding energies

Front 21

K shell L shell M shell N shell O shell P shell

binding energies

Back 21

69.5 ke12.1 keV2.82 keV0.6 keV0.08 keV0.008 keV

Front 22

To remove an orbital electron, the filament electron must have kinetic energy equal to or greater than

Back 22

the binding energy of the electron with which it interacts.

Front 23

Filtration

Back 23

absorbs low energy photons

reduce patient dose

Front 24

Inherent filtration

Back 24

Inherent to the tube head assemblyThe target window is the primary contributor.5mm Al equivalent

Front 25

Added filtration

Back 25

In a general radiography tube head assembly, added filtration comes in the form of another 2.0 mm Al placed between the target window and the top of the collimato

Front 26

Total filtration

Back 26

2.5 mm

Front 27

the collimator is

Back 27

inherent

Front 28

Beam Quantity

Back 28

The total number of x-ray photons in a beamAffected by mAs, kVp, distance, and filtrationThe radiographer should associate quantity with radiation doseAll other factors remaining constant, an increase in quantity increases the radiation dose delivered to the patient.When adjustments in quantity are desired, mAs is the factor adjusted.

Front 29

Beam Quantity

Back 29

Beam quantity varies as the square of the ratio of the change in kVp.If kVp is doubled, the intensity (quantity) increases by a factor of four.A 15% increase in kVp is equivalent to doubling the mAs.Beam quantity is strongly affected by changes in kVp because it is kVp that gives kinetic energy to the filament electrons.

Front 30

Beam Quantity

Back 30

Beam quantity varies inversely as the square of the distance.This is the inverse square law, which states that the intensity of a beam is inversely proportional to the square of the distance. The law is expressed as follows: I1/I2 = d22/d21

Front 31

Beam quality

Back 31

The penetrating power of the x-ray beam.

Front 32

Penetration

Back 32

This refers to those x-ray photons that are transmitted through the body and reach the image receptor.Some x-ray photons must penetrate the anatomic area of interest, or no image would result. Photons that reach the image receptor create the dark shades of the image.Areas where no photons reach result in the light or clear areas of the image.

Front 33

x axis

Back 33

photon energy

Front 34

y axis

Back 34

quantity

Front 35

Emission Spectrum

Back 35

Brems radiation produces a continuous spectrum

Front 36

Average keV is approximately _____ of the selected kVp

Back 36

30-40%

Front 37

Characteristic peaks at

Back 37

69

Front 38

Change in mA, time, or mAs

Back 38

changes beam amplitude

Front 39

Change in kVp

Back 39

Changes beam amplitude and average energy

due to increase in kinetic energy provided to incident electrons

Front 40

decrease voltage ripple

Back 40

increase quanity and increase quality

Front 41

What 3 things are needed for the production of x-rays

Back 41

A means of separating electronsA means of accelerating electrons (How fast do these electrons travel?)A means of stopping the electrons

Front 42

Which type of interaction produces x-rays through out the diagnostic range

Back 42

Bremsstrahlung interactions produce x-rays through out the diagnostic range.

Front 43

What factors have an effect on the x-ray emission spectrum and describe how the spectrum is affected by each factor

Back 43

A change in kVp affects both the amplitude and position of the x-ray spectrum. Changing mA will have a direct proportional change in the amplitude of the x-ray spectrum at all energies. Adding filtration increases the quality of the beam because low-energy x-rays are removed from the beam, thereby hardening the beam. As the atomic number of the target material increases high-energy x-ray production increases. Finally, using three-phase power instead of single-phase power effectively doubles the mAs; therefore, the amount of mAs used for an exposure can be decreased.

Front 44

Describe the characteristic interactions

Back 44

The characteristic interaction occurs when an incident electron has sufficient energy to remove an inner-shell electron that leaves a hole in that orbital shell. The hole is then filled with an electron from a higher power shell and the process continues on until the outer most shell has a vacant electron hole.

Front 45

What is an incident electron

Back 45

An incident electron begins in the thermionic cloud, which is burned off the filament in the cathode. When there is sufficient charge, the incident electrons leave the thermionic cloud and bombard the anode target.

Front 46

How does the x-ray circuit influence the production of x-rays?

Back 46

Three-phase and high-frequency circuits are more efficient and have a higher average voltage compared to a single-phase unit. This higher average voltage creates higher energy and higher intensity for the same mA and kVp settings. This increase in intensity allows the radiographer to use less mAs for an exposure, thereby reducing patient and radiographer exposure to radiation.

Front 47

If a filament electron leaves the tungsten atom with 15 keV of energy and the brems photon produced was 65 keV, how much energy did the incoming filament electron have?

Back 47

80

Front 48

With characteristic interactions, only those involving the _____ are of sufficient energy to be useful. All others are too weak to contribute to the radiographic image and are typically filtered out

Back 48

k shell

Front 49

The filament electron is more likely to miss the orbital electrons of the target atom because they are in _____ _______ and the atom is mostly empty space.

Back 49

constant motion

Front 50

The total number of x-ray photons in a beamAffected by mAs, ____, distance, and _______

Back 50

kvp, filtration

Front 51

.Beam quantity is strongly affected by changes in kVp because it is kVp that gives ________ to the filament electrons.

Back 51

kinetic energy

Front 52

Brems radiation produces a ________ spectrum

Back 52

continous

Front 53

A change in kVp affects both the________ and ________ of the x-ray spectrum

Back 53

amplitude, position

Front 54

Changing mA will have a _______ _______ change in the amplitude of the x-ray spectrum at all energies.

Back 54

direct proportional

Front 55

As the atomic number of the target material increases high-energy x-ray production _______

Back 55

increases