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SRNAChem&Physics > Radiation/Imaging > Flashcards

Radiation/Imaging Flashcards

1
Q

Conduction

A

• Direct transfer of energy through physical contact

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2
Q

Convection

A

• Indirect transfer of energy through a medium (ex. Heated air)

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3
Q

– Radiation

A

• Transfer/Emission of energy as electromagnetic waves or moving subatomic particles, especially high-energy particles that cause ionization.

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4
Q

Energy can be transferred from one object to

another in three ways

A

Conduction
Convection
Radiation

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5
Q

&Electromagnetic (EM) - photons

A

– Gamma rays
– X-rays
– UV

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6
Q

Particulate

A

– Alpha (He2+ nucleus)

– Beta (electron or positron)

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7
Q

Electromagnetic Radiation (EM)
• Composed of________
• Varying amounts of energy depending on_________

A

photons

wavelength (λ) & frequency (ƒ)

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8
Q

Isotopes –

A

two or more forms of the same element with an equal numbers of protons but different numbers of neutrons in their nuclei

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9
Q

differ in relative____________but not in ________

A

atomic mass but not in chemical

properties

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10
Q

________emit subatomic particles to decay down

to a stable state

A

• Unstable,

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11
Q

AS it loses protons, becomes less stable

A

also lose neutrons

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12
Q

Ex. of alpha decay – atom of Uranium 238

–

A

Emits an alpha particle (Helium nucleus)

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13
Q

β− decay (electron emission) –

n → p + e- + oῡe

A

neutron is converted into a proton, an electron, and an

antineutrino

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14
Q

Formula for B- decay

A

n → p + e- + oῡe

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15
Q

β+ decay (positron emission) –

A

proton is converted into a neutron, a positron, and a

neutrino

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16
Q

Formula for B+ decay

A

p → n + e+ + υe

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17
Q 
Electron Capture Decay (“K-capture”)
Define
The neutrino is \_\_\_\_\_\_\_\_From the 
If the new nucleus is left in an excited state, \_\_\_\_\_\_\_\_will also be emitted
formula?
A

• When an inner shell e- is drawn into the nucleus
and combines with a proton, forming a neutron and
a neutrino.
The neutrino is ejected from the atom’s nucleus.
• If the new nucleus is left in an excited state, gamma
rays (γ) will also be emitted.

p+ + e- → n + υe + γ

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18
Q

Half-Life (t1/2)

A

• The time it takes for the radioactivity of a specified

isotope to decay to half its original value.

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19
Q

• Example of Half life

A

• If we start with N0 atoms, after one half-life ½N0
remain.
• After two half-lives, ¼ N0 are left.
• After three half-lives 1/8 N0 are left and so forth.
• After seven half-lives, only (1/2)7 N0 remain.

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20
Q

Scatter Radiation

A

Occurs as a result of attenuation of the incident

beam to the patient’s body.

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21
Q

Three types of scatter radiation are

A

Coherent, Compton, Photoelectric

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22
Q

***Coherent scatter

• a.k.a.

A

“Thompson scatter”
– Occurs when an incident photon collides with an atom.
– The atom momentarily absorbs the energy and moves
into an excited states.
– The atom then releases the same energy as another
photon traveling in a different direction as scatter rad.

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23
Q

***Compton Scatter

A

Occurs when incident photon collides with outer
orbital e-. The e- is ejected from its orbit. The
photon is deflected from its original path and
continues with decreased energy in a new direction
as a scatter radiation.

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24
Q

*****Photoelectric scatter

A

• Occurs when an incident photon collides with an
inner shell orbital e-. The e- is ejected. When an
outer orbital e- moves to the inner orbit to fill the
vacated space, the difference in binding energy
between the 2 electron shells is emitted in the form of a new scatter photon.

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25
Q

Ionizing vs. Non-ionizing

A

• Ionizing radiation carries enough energy to free
electrons from atoms or molecules, thereby ionizing
them.
• Ionization of cell structures, organelles and DNA cause
severe cellular damage.

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26
Q

Penetrating energies are measured in electron volts

eV

A
  • a unit of energy ~ equal to 1.6×10^-19 joules
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27
Q

Alpha particles can be stop by

A

paper or skin

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28
Q

Beta particles can be pass ______And stop by _____

A

Human tissue: thin aluminum

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29
Q

Gamma rays particles and xray

A

thick sheet of iron and lead can stop it

30
Q

Neutrons

A

thick wall containing hydrogen can stop

31
Q

Boundary of ionizing photon energy is

A

between 10eV and 33 eV in the UV range.

32
Q

Non ionizing

A

Radio
Microwave
Infrared
Visible

33
Q

Ionizing

A

mid ultraviolet
Xray
Gamma

34
Q

2 types of cell interactions from ionizing radiation:

A

– Direct hit

– Indirect hit

35
Q

• Direct hit:

A

breakage of a DNA molecule as a result of

being struck directly by EM or Particulate radiation.

36
Q

• Indirect hit:

A

H2O breakage into H+ + OH- free radicals,
which then chemically damage DNA.
Cells may mutate and die

37
Q

Somatic effects

A

– Short-term

– Long-term (“latent”)

38
Q

Short term effects
Heme
GI
CNS

A

Further categorized according to body system
affected:
– Hematologic (dysplastic anemia)
– GI (“radiation sickness” damaged mucosal lining w/ infx)
– CNS (seizures, coma, death)

39
Q

Short term effects occurs

A

3 months after exposure

Involve very high doses (

40
Q

Long-term Effects

• Observed at_______Avg________

A

5 – 30 years, avg. at 10 – 15 years

41
Q

• Latent effects of long term low dose ionizing radiation

–

A

Cataracts (with extensive fluoroscopy)
– Cancer (skin, thyroid, breast & leukemia)
– Shortened Life span

42
Q

Genetic effects

A

• Occurs with radiation exposure to reproductive
organs (testes & ovaries)
• Involve mutations to the genes of the reproductive
cells
• Mutations carried over to progeny

43
Q

Two systems used to measure radiation dose:

A

conventional and SI units

44
Q

Conventional units

A

Roentgen
Rad
Rem

45
Q

Roentgen (R) is a

A

unit of Exposure

46
Q

1 R =

A

2.58 x 10^-4 C/kg

47
Q

Rad (rad) is a unit of
• Absorbed Dose =
• Rad stands for “

A

Absorbed Dose (D)
the amt. of energy per unit mass
absorbed by tissue.
Radiation absorbed dose”

48
Q

1 roentgen ~ 1Rad
• Corresponding SI unit is the
• 1 Gy = rad
• 1 rad =

A

of absorbed dose in muscle tissue
Gray (Gy)
100
0.01 Gy

49
Q

Rem (rem) is a unit of
• Biologic effects of radiation vary according to the_________
• Rem stands for_________
• Corresponding SI unit is the Corresponding SI unit is the

A 
Equivalent Dose (EqD)
type of radiation involved.
“radiation equivalent man”
Sievert Sievert (Sv)
50
Q
  • To calc. occupational dose, a radiation_____________

* WR values are based on

A 
weighting factor (WR) is assigned to each type of radiation.
variation of biologic
damaged produced by each type of radiation.
51
Q 
Equivalent dose (EqD) is calculated by multiplying
absorbed dose by
A

D x W(r)R = EqD

52
Q

• Ex. Worker receives 10rads alpha particles and

5rads x-rays. EqD =

A

• (10rads x 20 = 200) + (5rads x 1 = 5)

53
Q

1 Sv = _____rem

• 1 rem = ______Sv

A

100

0.01

54
Q

Doses are__________ in occupational exposure, devices (dosimeters) are worn to

A

cumulative

monitor doses received.

55
Q

______of the common units are typically used

A

1/1000

56
Q

Dosimeter “film badges”

A
  • Common types include thermoluminescent-type
    (TLD)
  • optically stimulated luminescence-type (OSL)
57
Q

ALARA -acronym:

A

As Low As Reasonably Achievable

58
Q

3 Factors of ALARA: –TDS

A

Time – Distance – Shielding

59
Q

Shielding Equipment:

A
  • Lead aprons
  • Thyroid shields

Pb gloves
Leaded glasses

60
Q

Ionizing Tests: examples

A

x-rays, CT, nuclear scans

61
Q

Non-ionizing Tests:

A

US, MRI

62
Q

______most common ordered imaging study (second

to________

A

CXR

dental films

63
Q

PET – Positron Emission Tomography

A 
• Pt. injected with beta emitter
• FDG (fluorodeoxyglucose)
• Fluorine
-18 tagged to glucose
• Sensors detect emissions from pt.
64
Q

PET/CT

A

• Combines both tests in one machine, provides
highly detail information of anatomy and cell
physiology in one test.

65
Q

SPECT scan

A

• Single-photon emission computed tomography
• Unlike PET/CT, Spect uses gamma emitting
radioisotope (ex. Galium111)
• 3D images for neurologic and cardiac studies

66
Q

MRI

A

• Non-ionizing. Magnetic field aligns H2O molecules
• RF disturbs H2O, molecules reorient, sensors record
as image

67
Q

ECHO 2 types

A

TEE vs. TTE

68
Q

TEE Advantages: –

A 
Heart rests on esophagus, only a few mm of tissue vs.
chest wall (skin, fat, muscle, bone, lung tissues) – Better visualization of structures
69
Q

TEE Disadvantages: –

A

Pt. must be NPO – Takes longer than TTE – Requires sedation or Gen. anesthesia

70
Q 
Ultrasound: Ionizing/nonionizing
Transducer contain what?
waves reflect?
Receiver senses
Used in \_\_\_\_\_\_\_\_\_
• For optimal visualization of structures, transducer must
be
A

• Non-ionizing. Uses sound waves to image.
• Transducer contains piezoelectric crystal that
vibrates to generate high freq. sound waves.
• Waves reflect off internal structures.
Receiver senses reflected signal echo.
•Used in regional anesthesia.
manipulated.

71
Q

Echogenic needles

A

Common needles used for regional blocks
• Smooth needles (A.) reflect sound energy away
from transducer.

SRNAChem&Physics (13 decks)

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