Characteristic x-rays

Question 1

Characteristic x-rays result when the interaction is violent to ionize the target atom through total removal of an _____________ _________.

Answer 1

inner-shell electron

Question 2

What happens if an incident electron from the cathode possesses at least 69 keV?

Answer 2

it can collide with and remove a K-shell electron from a tungsten atom

Question 3

What percentage of characteristic x-rays make up the primary beam when 70+ kVp are selected?

Answer 3

about 10%

Question 4

What is the cascading effect?

Answer 4

when the cathode electron ionizes a target atom by removing a K-shell electron, and the L-shell moves into the vacancy

Question 5

What happens when there is a void in the K-shell?

Answer 5

the L outer-shell falls into the void

Question 6

The transition of an orbital electron from an outer shell to an inner shell is accompanied by the emission of an _______.

Answer 6

x-ray

Question 7

What happens when an outer shell electron drops into an inner shell to fill a void left by ionization?

Answer 7

a characteristic photon is produced

Question 8

L-shell electrons have a binding energy of ________

Answer 8

12 keV

Question 9

How much keV is the leftover electron in a Tungsten atom?

Answer 9

69 keV - 12 keV = 57 keV

Question 10

The energy of x-rays created by the K-shell electron interaction is _____________.

Answer 10

predictable
(they’re always 57 keV)

Question 11

What does it mean when we say characteristic x-rays make up the “discrete” spectrum of x-rays?

Answer 11

they make up a very small portion of the total spectrum of the beam

Question 12

At 100 kVp, the percentage of characteristic x-rays will increase to approx. ______ of the primary beam.

Answer 12

15%

Question 13

Characteristic x-rays are ______________ than bremsstrahlung x-rays and vice versa

Answer 13

no better

Question 14

In the spectrum graph, characteristic x-rays are the _______ and everything else is bremsstrahlung

Answer 14

spike

Question 15

the number of protons determines the ________ __________ of the atom

Answer 15

atomic number

Question 16

What are atoms comprised of?

Answer 16

a nucleus surrounded by shells that contain electrons

Question 17

What does the nucleus contain?

Answer 17

the atom’s protons and neutrons

Question 18

At 65 kVp how many characteristic x-ray photons will be produced?

Answer 18

none

Question 19

What is the minimum energy for a cathode electron to ionize a tungsten atom?

Answer 19

69 keV

Question 20

What happens if there is no ionization?

Answer 20

there is no cascading effect, which results in no characteristic x-ray

Question 21

What percentage of the primary beam will be made of characteristic photons with a kVp setting of 65?

Answer 21

0%

Question 22

During the process of characteristic x-ray production, the cascade effect refers to the:

Answer 22

electron transfer from the outer shell to the inner shell

Question 23

Electron binding energy is defined as the:

Answer 23

energy required to remove an electron from orbit

Question 24

What is the approx. energy of photons at position C (characteristic photons) of the spectrum?

Answer 24

69 keV

Question 25

The most useful characteristic x-ray photons are produced when incident electrons interact with what?

Answer 25

inner shell electrons

Question 26

How much energy is required to remove a K-shell electron from a tungsten atom?

Answer 26

69 keV

Question 27

What name is given to the innermost electron shell within an atom?

Answer 27

K-shell

Question 28

A characteristic photon’s energy depends on what two variables?

Answer 28

energy of the incident electron

binding energy of orbital electrons