Chapter 8

Question 1

X-ray photons are produced when the _________________ from the cathode strike an anode target.

Answer 1

High-speed electrons

Question 2

What is the primary difference between x-rays and gamma rays?

Answer 2

That x-rays are human-made.

Question 3

All target interactions occur within ____ - ____mm of the surface of the target.

Answer 3

0.25-0.5

Question 4

What percentage of the kinetic energy is the incident electrons is converted to heat?

Answer 4

Over 99.8%

Question 5

Why are modern x-ray tubes tremendously inefficient?

Answer 5

They waste over 99% of the energy they use

Question 6

As the kinetic energy of the incident electrons increases, so does ____________________________.

Answer 6

The efficiency of photon production

Question 7

What are the two types of target interactions that can produce diagnostic-range x-ray photons?

Answer 7

Bremsstrahlung interactions & characteristic interaction

Question 8

What two things will occur to decide which interaction will take place?

Answer 8

Electron kinetic energy and the binding energy of the electron shells of the atom

Question 9

What two metals are used as target materials?

Answer 9

Tungsten & rhenium

Question 10

Why are tungsten and rhenium used as target materials?

Answer 10

As an effort to provide appropriate-atomic-number atoms and a maximum number of similar electron-shell binding energies.

Question 11

How was bremsstrahlung interactions named?

Answer 11

By the German word for braking or slowing

Question 12

When will berms interactions occur?

Answer 12

When the incident electron interacts with the force field is the nucleus

Question 13

The incident electron must have enough _______ to pass through the orbital shells and approach the nucleus of the atom.

Answer 13

Energy

Question 14

Why is there a mutual attraction between atomic nuclei and the incident electron?

Answer 14

Because atomic nuclei have a positive charge and the incident electron has a negative charge.

Question 15

Why does the incident electron lose energy and change direction?

Answer 15

The force field is too powerful for the electron to penetrate. It causes it to slow down and diverts the electron.

Question 16

How can you determine the amount of kinetic energy lost by the incident electron in a berms interaction?

Answer 16

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

Question 17

What is the only way the electron would drift away to join the current flow in berms interaction?

Answer 17

When the incident electron loses all of its excess kinetic energy.

Question 18

Can a single incident electron cause more than one brems interaction?

Answer 18

Yes, they can cause numerous interactions in many different atoms before losing enough energy to become included in the current flow.

Question 19

A characteristic interaction can only occur when?

Answer 19

The incident electron interacts with an inner-shell electron.

Question 20

The incident electron must have enough energy to do what in a characteristic interaction?

Answer 20

To knock an inner-shell electron from orbit

Question 21

What happens to the atom when the incident electron knocks an inner-shell electron from orbit?

Answer 21

It ionizes the atoms

Question 22

After the incident electron interacts in a characteristic interaction, does the incident electron continue on its original path or go on a different path?

Answer 22

It goes on a new path in a slightly different direction.

Question 23

After the characteristic interaction the atom is considered _________, until an electron from another shell drops into the hole.

Answer 23

Unstable

Question 24

What is the characteristic cascade?

Answer 24

When an outer-shell electron has dropped to fill the hole, another electron will drop to fill the hole it left so on until only the outer- most shell is missing an electron.

Question 25

Is brems photons or characteristic photon energy so predictable?

Answer 25

Characteristic photon energy

Question 26

Is brems photon energy or characteristic photon energy used by spectroscopy using the measurements of their photon energies to determine what types of atoms make up the sun, stars, and other celestial bodies?

Answer 26

Characteristic

Question 27

What is the binding energy for the K-shell electrons?

Answer 27

69.5 keV

Question 28

What is the binding energy for the L-shell electron?

Answer 28

12.1 keV

Question 29

What is the binding energy for the M-shell electrons?

Answer 29

2.8 keV

Question 30

What is the binding energy for the N-shell electrons?

Answer 30

0.6 keV

Question 31

What is the binding energy for the O-shell electrons?

Answer 31

0.08 keV

Question 32

How can characteristic photons be created?

Answer 32

From the incident electron ionization of any shell and hole filling from any shell.

Question 33

A ____ variety of characteristics photon energy levels are produced.

Answer 33

wide

Question 34

Most characteristic interactions will produce?

Answer 34

heat

Question 35

Within the diagnostic x-ray range, mot photons are produced by __________ target interactions.

Answer 35

bremsstrahlung

Question 36

Characteristic photons will not comprise any useful beam until the kVp is above what number?

Answer 36

70 because removal of a K-shell electron from tungsten requires 69.5 keV

Question 37

Between 80 and 100 kVp, about __-__ percent of the primary beam is produced by brems interactions.

Answer 37

80-90

Question 38

Between 80 and 100 kVp, about __ -__ percent of the primary beam is produced by characteristic interactions.

Answer 38

10-20

Question 39

What two emissions combine to form the complete primary beam spectrum?

Answer 39

Brems and Characteristic

Question 40

The kilovolatage peak of the exposure is the _______ possible energy for any photons that exits the x-ray tube.

Answer 40

maximum

Question 41

kVp controls quality or quantity?

Answer 41

quality (energy)

Question 42

mAs controls quality or quantity?

Answer 42

quantity

Question 43

What is the x-ray emission spectrum affected by?

Answer 43

The quantity and composition of the materials through which it must pass to exit the x-ray tube and housing.

Question 44

While the x-ray beam is passing through the filtering materials what is being abasorbed?

Answer 44

lower-energy photons

Question 45

If filtration of the x-ray beam is increased, the image receptor exposure ______.

Answer 45

decreases; they are inverse