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trisemester 3 TCC > week 6 Xray physics up too chapter 10 > Flashcards

week 6 Xray physics up too chapter 10 Flashcards

1
Q

higher energy photons are produced by increasing what?

A

KVp

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2
Q

as you increase filtration what is affected?

‘beam hardening’

A

decreases the xray energy keV by absorbing the lower energy photons

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3
Q

inherent filtration

A

is built into the machine to remove the low energy photons

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4
Q

added filtration is done when you need?

A

to balance the intensity of x-ray exposure over an area of anatomy that is not uniform in density and/or thickness

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5
Q

what portion of the wedge is over the thin part of the thoracic spine?

A

the thick part

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6
Q

collimator is set to go straight through?

A

the dense part of the anatomy of the pt.

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7
Q

Penetrability =

A

ability of x-ray beam to penetrate

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8
Q

Attenuation =.

A

reduction of beam intensity due to absorption and scattering

of photons not quality

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9
Q

Half-value layer (HVL) =

A

that thickness of absorbing material that will cause the exiting beam intensity to be one-half of the entering (ie, incident) beam intensity

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10
Q

uniform attenuation is not seen in what kind of imaging?

A

diagnostic xray beam

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11
Q

For a beam NOT composed of monoenergetic photons, what actually happens to the half-value layer as the beam passes thru matter?

A

becomes thicker as the beam passes through matter

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12
Q

what do you think a tenth-value layer would be?

A

reduce it too a 10th of that value

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13
Q

Five basic interactions may occur betweeen matter and xray

A 
Coherent scattering
Photoelectric interaction
Compton interaction
Pair production
Photodisintigration
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14
Q

photons of electromagnetic radiation tend to interact with structures similar in size to their ________?

A

wavelength

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15
Q

Low energy photons (longer wavelength) tend to interact with

A

atoms

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16
Q

Moderate energy photons tend to interact with

A

electrons

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17
Q

Higher energy photons tend to interact with

A

nuclei

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18
Q

“classical scattering” or “Thompson scattering”

occurs at what energy levels?

A

photon energy levels below 10keV

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19
Q

coherent scattering affects what amount of xray photons?

A

small amount

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20
Q

during coherent scattering the xray energy is ______ and ________ from the atom

A
  1. absorbed

2. re-emitted

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21
Q

pair production?

A

Photon disappears and 2 oppositely charged pieces of matter (one electron and one positron) are formed

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22
Q

what is the Photodisintigration energy level

& this is between what two structures?

A

(>10MeV) photon and nucleus

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23
Q

pair production energy level between what two structures?

A

Interaction of high energy (>1.02MeV) photon and electromagnetic field of nucleus

24
Q

in photodisintigration what happens to the photon?

A

Photon disappears a nuclear fragment is emitted

25
Q

Photoelectric interaction?

A

Interaction of lower energy photons in the diagnostic x-ray beam

26
Q

does ionization occur during Photoelectric interaction?

A

yes, the photoelectron is ejected

27
Q

Photoelectric interaction involves electron from where atomic orbit?

A

inner shell

28
Q

what absorbs the energy of the xray?

A

inner shell electron due to

29
Q

KE + BE is equal to what?

A

the energy of the xray

30
Q

the photon that is produced in the photoelectric interaction?

A

secondary xray photon produced by xray not inside the tube (tungsten)

31
Q

is all of the energy absorbed in photoelectric interaction?

A

yes

32
Q

probability of photoelectric interaction is dependent on?

A

energy of the xray and the atomic number of the atom involved

33
Q

relationship of the xray energy and PE event?

A

inversely proportional to the 3rd power of the xray energy

34
Q

atomic number and PE relationship?

A

directly proportionally to the 3rd power of the atomic number (z#)

35
Q

compton interaction involves?

A

photons within the diagnostic spectrum that have intermediate to high energy

36
Q

in compton interaction the incident photon interacts with the

A

outer shell e-

37
Q

does ionization occur in compton?

A

yes

38
Q

what is the characteristic of incident photon in comptone?

A

scattered

39
Q

scattered photon means?

A

redirected from their original vecter and contains 2/3 or more of the incident photon NRG;

40
Q

with minimal direction change of a e- what happens to the energy loss

A

it will be minimally loss

41
Q

are scattered photons useful in image production?

A

no

42
Q

what is the caution of scattered photons?

A

potential to have othoer ionizing events to go on so they are hazardous

43
Q

Atomic number of the involved atom _____ affect Compton interaction probability

A

does not

44
Q

as compton interactions decrease what happens to the photon energy?

A

it will increase

45
Q

why are compton interactions more predominant when the average beam energy increases?

A

because photoelectric energy decreases more in xray energy; in turn increasing chance of compton interaction

46
Q

how do you control photon energies?

A

with kVp

47
Q

at about 80 kVp what is happening in regards to compton vs photoelectric?

A

about equal to eachother

48
Q

which one predominates at higher kVp in comparison to compton and photoelectric?

A

comptom

49
Q

differential absorption defintion?

A

difference in the absorbing ability between 2 different materials

50
Q

what influences the differential absorption (photoelectric interactions)?

A

the atomic energy

51
Q

as you from fat > soft tissue > lung > bone what happens to the atomic number?

A

it increases

* little difference between fat and other soft tissue

52
Q

how can you use contrast materials?

A

use the ones with greater atomic number to give an outline.

53
Q

what is the difference between compton interaction and photoelectric interactions in reagards to diagnostic imaging?

A

compton: does not contribute
Photoelectric: does contribute

54
Q

photoelectric interactions effect attenuation in what way?

A

they play a big role in it by decresing the number of photons as it goes through tissues

55
Q

how does scatter e- effect the attenuation?

A

decreases the # of photons in the beam with some backscatter

56
Q

mass density?

A

how many atoms are present per unit volume of material

trisemester 3 TCC (25 decks)

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