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MI 132 > MI 132 unit 4 > Flashcards

MI 132 unit 4 Flashcards

1
Q

target interactions

A

incident electrons interact w/ target atoms (tungsten) to produce x-rays in the following 2 ways: characteristic and Brems

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2
Q

what is the most common interaction ?

A

Heat

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3
Q

incident electrons

A

aka: filament electrons and projectile electrons
-electrons are boiled off from the cathode and interact at the anode

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4
Q

less than _% of electrons interact w/the ability of making x-ray

A

1%

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5
Q

excitation

A

related to the production of heat
-takes an ion/electron and makes it at a higher state
-not enough to kick out of orbit

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6
Q

what is a heat a result of

A

excitation, not ionization

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7
Q

Bremsstrahlung

A

interacts with the force field of the nucleus
-slows down incident electrons
-electron loses energy because It slowed down
-1 incident electron can have multiple interactions with its target

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8
Q

what is Brem’s course

A

Doesnt divert course because it is losing energy

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9
Q

how does distance effect Brem’s

A

distance from nucleus determines how much energy your electron is going to lose and how much the photon energy will be

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10
Q

what is the line difference in Brem’s and incident photons

A

=xray photons are a squiggly line
-incident photons are straight lines

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11
Q

Brem math

A

find the difference between energy it comes in with and what it leaves with

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12
Q

how does distance effect incident electrons

A

distance effects the amount of kinetic energy lost by incident electrons
-the CLOSER to the nucleus, the MORE energy LOST
-the FURTHER from the nucleus, the LESS energy LOST

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13
Q

where does Brems energy fall?

A

1/3 of kVp

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14
Q

how is max and min Brem’s determined

A

max: determined by kVp (if kVp is 80, Brems wont exceed 80)
min: immeasurable because it is so low

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15
Q

characteristic xray photons

A

ionization pf a target electron needed first and then electron will be kicked out of orbit
-higher energy electron will drop into lower energy shell and an xray photon is created

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16
Q

ionization in characteristics

A

ionization of k-shell (most inner shell) is important when thinking about characteristic interactions

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17
Q

characteristic math

A

difference in shell energy/ electron binding

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18
Q

what is the kVp for K-shell?

A

69.5
-for tungsten
highest photon energy will be farthest shell to closest shell

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19
Q

what changes characteristic xray photons ?

A

change in target material because it has a different binding energy

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20
Q

what happens to low kEv?

A

it is absorbed into the patient

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21
Q

k shell electrons

A

the only useful electrons that contribute to the image of your xray and its useful to characteristic interactions

22
Q

what does kVp change?

A

kVp does not change effect energy of the shell in Characteristics but it DOES in Brems

23
Q

characteristic cascade

A

when ionizing a shell, the shell that fills an open space will be empty until another shell fills the space

24
Q

characteristic photon produce when…

A

produce when an outer shell electron fills inner shell vacancy

25
Q

majority of photons exiting the shell are..

A

Brems
-because they are utilized with the nucleus

26
Q

what must kVp be set at to be useful ?

A

70
-this is in order to create k-shell characteristic xrays
-because the k shell is at 69.5

27
Q

what does filtration do?

A

filtration absorbs low energy because low energy doesn’t contribute to the images but it affects patients dose and filtration would help lower patient absorbed dose

28
Q

low energy vs high energy

A

low energy- soft and long wave length
high energy- hard and short wave length

29
Q

HVL

A

amount of absorbing material; that reduce intensity of beam to one half of its original value
-increasing technique increases dose given
-too much filtration would increase the HVL
-quality of beam as well

30
Q

what effects HVL

A

kVp and filtration

31
Q

what is the best measurement of beam quality

A

HVL

32
Q

inherent filtration

A

strictly part of the equipment
-tube and housing
-both windows
equal to 0.5 mm Al

33
Q

added filtration

A

outside of the tube housing
-can be removed

34
Q

why is Al used?

A

higher material will absorb more x-ray photons
-Al is easily shaped, cheap and readily available

35
Q

compensating filters

A

solve the problem of unequal or thickness exposure
-wedge: T spine and foot
-trough: chest
-boomerang: shoulder

36
Q

quality

A

energy
- high energy is more penetrating
-the more the penetration the darker the area on the xray
-effected by kVp

37
Q

quantity

A

increase in quantity in an increase inpatient dose
-mAs is directly proportional and the main control for quantity
-kVp will also increase quantity so it is direct but not proportional because there is a bigger change

38
Q

what happens when kVp is doubled ?

A

increasing kVp will quadruple quantity
-doubling kVp doesnt really exist

39
Q

how much does kVp increase by?

A

15%

40
Q

how does SID effect quantity ?

A

double SID and inverse square law have an inverse re;ationship
-double the SID is 1/4th of beam quantity

41
Q

distance

A

cutting distance will quadruple exposure because it is closer to the patient

42
Q

why don’t we change filtration ?

A

we are unsure how much it would change by

43
Q

what does decreasing mAs do

A

decreases quantity and doesnt effect quality

44
Q

what does increasing kVp do

A

increases quantity and increases quality

45
Q

what does decreasing distance do

A

increases quantity and doesnt effect quality
-inverse square law

46
Q

what does increasing filtration do

A

decreases quantity and increases quality

47
Q

x axis and y axis

A

x axis is quality (kVp)
y axis is quantity (mAs)

48
Q

characteristic is what type of graph

A

discrete emission spectrum (line)
-can only be created at specific energy or kVp level
-homogenous

49
Q

what type of graph is Brem’s

A

continuous (curve)
-can be created from 0 to anywhere
-top of the bell curve always falls at 1/3 of the kVp (peak

50
Q

quantity and quality appearance

A

quantity is amplitude and quality is shift on x- axis

51
Q

what happens when target material goes up ?

A

increase in quantity and quality

MI 132 (2 decks)

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