Chapter 7 Exam

Question 1

Radiographic density refers to overall _______ on image receptor

Answer 1

blackness

Question 2

Classical interactions has 3 names:

Answer 2

classical, coherent scattering, Thompson scattering

Question 3

What interactions and effects do we deal with the most?

Answer 3

classical interactions, Compton scattering, and photoelectric effect

Question 4

Classical interactions result in:

Answer 4

scatter x-rays

Question 5

high-energy photons interact with random electron and gets deflected in new direction
- Ionizes the atom (makes it unstable)
- Electron leaves the atom with enough energy to have an interaction with another atom close to it
- Results in image fog (also called noise)
- Happens a lot, not good

Answer 5

compton scattering interaction

Question 6

x-ray photons are totally absorbed

Answer 6

photoelectric interaction

Question 7

Increased tissue density _______ radiographic density

Answer 7

decreases

Question 8

Decrease tissue density (ex: adding air) ________ radiographic densities because x-rays can get through easier

Answer 8

increases

Question 9

Increasing tissue density ________ radiopaque

Answer 9

increases

Question 10

Decreasing tissue density ________ radiolucency

Answer 10

increases

Question 11

produces two particles-positron & electron, happens outside of diagnostic imaging

Answer 11

Pair production

Question 12

Incident photon =

Answer 12

1.022 MeV (very big)

Question 13

does not occur in radiography (10 MeV or more)

Answer 13

photodisintegration

Question 14

gives us the ability to have different tissue densities and contrast in an image
The higher the Z number the more dense the atom is and the more likely it is to absorbs

Answer 14

differential absorption

Question 15

____ creates more radiographic density

Answer 15

Air

Question 16

_____ creates less radiographic density

Answer 16

Metal

Question 17

Which of the following is a major source of occupational exposure?

Answer 17

Compton interactions

Question 18

Which interaction, within the diagnostic range, does not involve the removal of an orbital electron?

Answer 18

Classical scattering

Question 19

Which interaction requires 1.02 MeV of energy?

Answer 19

Pair production

Question 20

A photon of 10 MeV colliding with a nucleus will likely result in what type of interaction?

Answer 20

Photodisintegration

Question 21

Which technique will produce the greatest number of photodisintegration events in an average abdomen? 120 kV and 5 mAs, 108 kV and 10 mAs, 98 kV and 20 mAs, none of the above

Answer 21

None of the above

Question 22

Which of the following events will not occur in the diagnostic range of x-ray energies? Classical, compton, photoelectric, photodisintegration

Answer 22

Photodisintegration

Question 23

Positive contrast media is administered to increase what type of interactions?

Answer 23

Photoelectric

Question 24

Which of the following contributes most to image fog? Classical, photoelectric, pair production, compton

Answer 24

Compton

Question 25

Which interaction in the diagnostic range involves the total absorption of the incident photon?

Answer 25

Photoelectric effect

Question 26

When the kV selected is equal to or slightly greater than the inner-shell binding energy of a target tissue atom, which interaction predominates?

Answer 26

photoelectric

Question 27

* Also called coherent or Thomson scattering * The incident x-ray photon interacts with an orbital electron of a tissue atom and changes direction * Incident wavelength equal to scattered wavelength * Energy below 10keV (little importance to diagnostic x-ray)

Answer 27

classical interactions

Question 28

An incident x-ray photon enters a tissue atom, interacts with an orbital electron, and removes it from its shell; it loses up to one third of its energy and is usually deflected in a new direction

Answer 28

compton interaction

Question 29

compton interaction formula

Answer 29

Ei = Es + (Eb + Eke) Ei = incident photon energy Es = scatter photon energy Eb = electron binding energy Eke = photoelectron kinetic energy

Question 30

ionizes the atom making it unstable the ejected electron leaves the atom with enough energy to go through interactions of its own adjacent atoms the incident photon is deflected in a new direction and is now a compton scatter photon with enough energy to go through other interactions in the tissues or exit the patient and interact with the image receptor

Answer 30

compton interactions

Question 31

Is one of the most prevalent interactions between x-ray photons and the human body in general diagnostic imaging

Answer 31

compton scatter

Question 32

Probability NOT dependent on the atomic number of atoms involved but is related to the energy of the photon

Answer 32

compton scatter

Question 33

The incident x-ray photon interacts with the inner-shell electron of a tissue atom and removes it from orbit

Answer 33

photoelectric interactions

Question 34

The tissue atom is ionized and the inner-shell vacancy makes the atom unstable To regain stability, a ________________ occurs, producing secondary x-ray photons These secondary photons are of low energy, are absorbed by the body in other photoelectric events, and contribute to patient dose

Answer 34

characteristic cascade photoelectric interactions

Question 35

photoelectric interaction equation

Answer 35

Ei = Eb + Eke Ei = Incident photon energy Eb = Electron binding energy Eke = Photoelectron kinetic energy

Question 36

The probability of photoelectric interaction depends on the following:

Answer 36

The atomic number of the tissue atoms with which they interact The incident x-ray photon energy

Question 37

factors affecting the photoelectric-compton ratio

Answer 37

Z# of the material Photon energy

Question 38

Occurs when the incident x-ray photon has enough energy to escape interaction with the orbital electrons and interact with the nucleus of the tissue atom

Answer 38

pair production

Question 39

Produces two particles: a positron and an electron

Answer 39

pair production

Question 40

For these particles to exist, they must each have energy of 0.51 MeV. Both particles travel out of the atom. The electron undergoes many interactions before coming to rest in another atom. The positron travels until it strikes an electron, causing an annihilation event. Does not occur in radiography

Answer 40

pair production

Question 41

Occurs when photons with extremely high energies strike the nucleus of the atom and make it unstable The nucleus of the atom involved regains stability by ejecting a nuclear particle Does not occur in radiography (10 MeV or more)

Answer 41

photodisintegration

Question 42

The difference between x-ray photons that are absorbed photo-electrically versus those that penetrate the body Different body structures absorb x-ray photons to different extents

Answer 42

differential absorption

Question 43

those photons that are attenuated by the body and do not reach the image receptor

Answer 43

absorption

Question 44

those x-ray photons that pass through the body and reach the image receptor

Answer 44

transmission

Question 45

factors affecting differential absorption:

Answer 45

higher atomic number (Z), increased kVp, increased mass density

Question 46

what are the three most common effects in radiobiology:

Answer 46

main-chain scission cross-linking point lesions

Question 47

which of the following is NOT one of the five basic x-ray interactions with matter?

Answer 47

bremsstralung

Question 48

after compton scattering, the scattered x-ray has:

Answer 48

longer wavelength

Question 49

the probability that an x-ray will interact with an outer-shell electron is influenced principally by:

Answer 49

the energy of the incident x-ray

Question 50

the compton effect is:

Answer 50

independent of Z

Question 51

which term describes how different body structures absorb x-ray photons to different extents?

Answer 51

differential absorption

Question 52

how does a higher atomic number (Z) affect PE absorption?

Answer 52

increases PE absorption

Question 53

how does a higher atomic number (Z) affect compton scatter?

Answer 53

compton scatter is unaffected

Question 54

how does a higher atomic number (Z) affect transmitted x-rays?

Answer 54

decreased transmitted x-rays

Question 55

how does higher kVp affect PE absorption?

Answer 55

decreases PE absorption

Question 56

how does higher kVp affect compton scatter?

Answer 56

relatively increases compton scatter

Question 56

how does higher mass density affect PE absorption?

Answer 56

increases PE absorption

Question 56

how does higher kVp affect transmitted x-rays?

Answer 56

increases transmitted x-rays

Question 57

how does higher mass density affect compton scatter?

Answer 57

increases compton scatter

Question 58

how does higher mass density affect transmitted x-rays?

Answer 58

decreases transmitted x-rays