Exam Review 9/4 PPT3

Question 1

Bremss or Characteristic? Electrons interact with a nucleus

Answer 1

Bremss

Question 2

Bremss or Characteristic? Electrons interact with orbital e-

Answer 2

Characteristic

Question 3

A high speed electron passes near a nucleus and is deflected from its pass after being acted upon by Coulomb forces. They lose energy, slow down and propagates the energy through space.

Answer 3

Bremss

Question 4

T or F?
Electron can engage in multiple Bremsstrahlung interactions

Answer 4

T

Question 5

What determines the energy for Brem?

Answer 5

How close it gets to nucleus and how much it makes it change its path.

Question 6

Probability of bremms production varies with __ of the target

Answer 6

Z^2

Question 7

Bremms produces a ___energetic beam

Answer 7

Poly

Question 8

Average energy for bremss?

Answer 8

E avg = 1/3 max photon energy

Question 9

Explain this graph

Answer 9

…

Question 10

Why doesn’t graph start at 0?

Answer 10

Bc the beam is filtered

Question 11

Explain the peaks in this graph

Answer 11

Sharp peaks on graph occur when vacancies are produced and electrons drop down to fill the gap. They occur at specific energies for each element.

Question 12

What is the avg energy ?

Answer 12

1/3 of 150 = 50keV

Question 13

An electron interacts with an atom by ejecting an orbital electron, which leaves the atom ionized. A vacancy is created and an outer
orbital electron will fall down to a closer orbital. When an electron moves down there is an energy potential, which results in x-rays.

Answer 13

Characteristic

Question 14

Characteristic produces a ___energetic beam

Answer 14

mono

Question 15

mA and mAs: If you double mA, how does it affect output?

Answer 15

Output is doubled

Question 16

kVp.. slide 17

Answer 16

..

Question 17

What happens if you increase energy? Does it affect characteristic and bremss?

Answer 17

It does not affect characteristic.
It will only affect the Bremss.

Question 18

For characteristic x-rays, would you see the same energies produced for different targets?

Answer 18

No, they have diff binding energies

Question 19

Atomic # of tungsten

Answer 19

74

Question 19

What doe this graph show?

Answer 19

The higher the energy of the beam, the more forward the angular dependence is (the more forward the beam is)

Question 20

What does a voltage rectifier do?

Answer 20

allows current flow in only one direction

Question 21

Explain what is happening here and why?

Answer 21

HVL thickness will increase for each succeeding HVL in a polyenergetic beam due to the first one hardening the beam (filtering out the lower energy photons) and the resulting energy of the beam being higher.
In monoenergetic beams, the same HVL will be used.

Question 22

low E photons are filtered out and the beam therefore acquires a higher average energy than before

Answer 22

beam hardening

Question 23

What is meant by: To measure a beam’s transmission through an absorber, the
measurement must be done under “good geometry”?

Answer 23

Beam must be measured where there isn’t scatter - don’t want to measure scattered photons.

Question 24

Anode-heel effect

Answer 24

..

Question 25

Inherent filtration

Answer 25

..

Question 26

___ filtration attenuates both low & high-energy photons, but a larger fraction of low energy photons are attenuated

Answer 26

Added filtration

Question 27

___ filtration includes the glass or metal enclosure of an x-ray tube

Answer 27

Inherent