Physics Ch 9 Nuc Med Flashcards

1
Q

neutrons > protons –> what kind of decay?

A

beta minus

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2
Q

protons > neutrons –> what kind of decay?

A

beta plus

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3
Q

what happen in beta minus decay?

A
  • beta particle eject
  • anti-neutrino eject
  • neutron change to proton
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4
Q

beta minus decay –> involve kind of transition? –> isobar/isotope/isotone?

A

isobaric –> same mass

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5
Q

beta minus decay –> should use what kind of shield –> lead/plastic?

A

plastic

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6
Q

what happen in beta plus decay?

A
  • positron eject
  • neutrino eject
  • proton change to neutron
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7
Q

what happen after positron emission?

A
  • travel very short distance
  • annihilate w electron
  • two 511 keV photons –> 180 deg apart
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8
Q

what happen in electron capture?

A
  • K shell electron –> into nucleus
  • proton change to neutron
  • release gamma photon
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9
Q

electron capture –> involve kind of transition? –> isobar/isotope/isotone/isomer?

A

1) isobaric –> same mass

2) isomeric –> release gamma photon

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10
Q

good for imaging?

  • beta minus decay
  • beta plus decay
  • electron capture
A
  • beta minus decay: no
  • beta plus decay: Y –> positron
  • electron capture: Y –> gamma
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11
Q

Tc-99m –> release what kind of photon? keV?

A

gamma –> 140 keV

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12
Q

cyclotron –> radioisotopes? (4)

A
  • molybdenum-99
  • fluorine-18
  • gallium-67
  • thallium-201
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13
Q

nuclear reactor –> radioisotopes? (4)

A
  • molybdenum-98
  • iodine-131
  • xenon-133
  • thallium-201
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14
Q

nuclear reactor –> radioisotope production –> cons? (2)

A
  • low yield of desired radioisotope

- produce undesired things

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15
Q

radionuclide generator –> radioisotopes? (2)

A
  • Tc-99m

- krypton-81m

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16
Q

radionuclide generator –> molybdenum-99 –> Tc-99 –> what must be done before can use Tc?

A

Tc in + state –> stannous ions –> reduce Tc to useable state

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17
Q

Tc-99 –> radionuclide purity test –> what is break-thru?

A

Mo that is in sample

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18
Q

NRC: Tc-99 –> how much breakthru is allowed?

A

time of admin –> 0.15 microCi Mo per 1 milliCi Tc

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19
Q

Tc-99 –> chemical purity test –> test for what?

A

Aluminum contamination

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20
Q

Tc-99 –> Aluminum contamination –> allowable amt?

A

<10 microgram Al per 1 mL

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21
Q

Tc-99 –> Aluminum contamination –> how test for it?

A

pH paper

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22
Q

Tc-99 –> Aluminum contamination –> manifestation on imaging? (2)

A
  • Tc scan –> liver activity

- sulfur colloid scan –> lung activity

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23
Q

Tc-99 –> radionuclide purity test –> which assay 1st? –> Mo vs Tc

A

Mo

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24
Q

presence of free Tc –> MOA? (2)

A
  • lack of stannous ions

- accidental air inject into syringe/vial

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25
Q

presence of free Tc –> imaging finding?

A

uptake in:

  • gastric
  • salivary gland
  • thyroid
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26
Q

Tc-99 –> radiochemical purity test –> test for what?

A

free Tc

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27
Q

Tc-99 –> radiochemical purity test –> how test for it?

A

thin layer chromatography

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28
Q

Tc-99 –> radionuclide purity test –> how test for it?

A

dose calibrator w lead shield

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29
Q

what is equilibrium?

A

concentration of parent isotope = conc daughter isotope

[Mo-99] = [Tc-99]

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30
Q

what is transient equilibrium? how many half lives to reach equilibrium? example?

A

parent isotope half life > daughter half life

4 half lives –> equilibrium for short time

Mo-99 –> Tc-99

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31
Q

what is secular equilibrium?

A

parent isotope half life&raquo_space;> daughter half life

parent & daugther reach equilibrium –> in equilibrium for long time

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32
Q

what is half life?

  • physical
  • biological
  • effective
A
  • physical: activity –> dec by 1/2
  • biological: eliminate (pee/poo) 1/2 substance
  • effective: considering both physical + biological half life
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33
Q

effective half life –> formula?

A

1/effective = 1/physical + 1/biologic

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34
Q

radioactive activity –> unit?

A
  • curie (Ci)

- SI unit –> Becquerel (Bq) = 1 disintegration per sec

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35
Q

nuc med –> what is specific activity?

A

activity per unit mass (Bq/g)

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36
Q

how specific activity relate to half life?

A

longer half life –> lower specific activity

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37
Q

how does collimator sensitivity affect resolution?

A

inc collimator sensitivity –> inc counts to be imaged –> dec resolution

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38
Q

how does distance affect collimator sensitivity?

A

no effect

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39
Q

collimator –> how does septal length (collimator depth) affect sensitivity? spatial resolution?

A
  • shorter septa: inc sens –> dec resolution

- longer septa: dec sens –> inc resolution

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40
Q

collimator –> how does hole diameter affect sensitivity? spatial resolution?

A
  • small hole: dec sens –> inc resolution

- bigger hole: inc sens –> dec resolution

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41
Q

collimator: low vs high energy tracer –> should use short/long septa length? small/big hole?

A

low energy:

  • short septa
  • small hole

high energy:

  • long septa
  • big hole
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42
Q

collimator –> 4 types?

A
  • parallel
  • pinhole
  • converging
  • diverging
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43
Q

pinhole collimator –> used to image what organ?

A
  • thyroid

- other small parts

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44
Q

pinhole collimator –> image charact:

  • not/magnify?
  • not/invert?
A
  • mag

- invert

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45
Q

converging collimator (cone beam) –> image charact:

  • not/magnify?
  • not/invert?
A
  • mag

- not invert

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46
Q

scintillation crystal –> thin vs thick –> how affect..

  • sens
  • spatial resolution
A

thin xl:

  • worse sens
  • better resolution

thick:
- better sens
- worse resolution

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47
Q

V/Q scan –> which image first? –> Xe vs Tc? why?

A

lower energy photon 1st: Xe –> Tc

if Tc first –> downscatter –> Xe –> can’t accurately pick up Xe peak

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48
Q

what is star artifact? MC seen in what situation?

A

collimator holes –> hexagonal pattern –> focal intense energy –> penetrate collimator septa –> star artifact?

high therapeutic dose –> thyroid scan –> use med energy collimator instead of high

49
Q

gamma camera –> quality control –> tested parameters? (4)

A
  • field uniformity
  • window setting
  • image linearity & spatial resolution
  • center of rotation
50
Q

gamma camera –> quality control –> what is field uniformity –> what test?

A

flood –> camera produce uniform image across entire xl surface?

51
Q

gamma camera –> quality control –> field uniformity –> how often?

A
  • extrinsic (w collimator) –> daily

- intrinsinc (no collimator) –> wkly

52
Q

gamma camera –> quality control –> field uniformity –> recommended count for extrinsic & intrinsic flood test?

A

5-10million counts

53
Q

gamma camera –> quality control –> energy window setting –> how often?

A

daily

54
Q

gamma camera –> quality control –> image linearity & spatial resolution –> how often?

A

wkly

55
Q

gamma camera –> quality control –> center of rotation –> how often?

A

monthly

56
Q

gamma camera –> quality control –> center of rotation –> how test?

A

done w Tc-99 point sources along axis of rotation –> axis should be straight

57
Q

ring badge –> how to properly wear?

A

dominant hand –> index finger –> label towards source (usu towards palm) –> glove over

58
Q

no lead apron in nuc med –> why? (2)

A
  • thin lead not stop gamma rays

- lead –> slow down gamma ray –> transform into Bremmstrahlung XR –> worsen dose exposure

59
Q

sodium iodine well counter –> like a small gamma camera –> good for what kind of samples? (3)

A
  • “wipe test” samples
  • blood
  • urine
60
Q

Geiger-Muller counter –> click once then stop –> what happened?

A

lrg radiation –> overload device –> “dead time” before device can respond again

61
Q

Geiger-Muller counter –> max dose before dead time?

A

100 mR/h

62
Q

when use ion chamber over Geiger-Muller counter? (2)

A
  • measure dose rate

- expect higher doses

63
Q

ion chamber –> exposure rate –> detectable range?

A

0.1-100 R/h

64
Q

dose calibrator (ionizing chamber) –> quality assurance –> what parameters need to be tested? (4)

A
  • consistency
  • linearity
  • accuracy
  • geometry
65
Q

dose calibrator (ionizing chamber) –> quality assurance –> what is tested? (4) how often?

A

CLAG:

  • constancy: daily
  • linearity: qtrly
  • accuracy: annual
  • geometry: when mv
66
Q

what is major spill?

  • Tc-99m
  • Tl-201
  • In-111
  • I-123
  • Ga-67
  • I-131
A
  • Tc-99m: >100 mCi
  • Tl-201: 100
  • In-111: 10
  • I-123: 10
  • Ga-67: 10
  • I-131: 1
67
Q

major spill occurs –> what do you do?

A
  • do NOT clean it up

- call radiation safety officer

68
Q

minor spill occur –> what do you do? 5 steps?

A

1) protect pt
2) confine spill/limit spread
3) clean spill
4) survey cleanup items
5) survey cleanup ppl

69
Q

minor spill occur –> contaminated items –> how many half lives to decay to safe level?

A

10

70
Q

wipe test –> does NOT work for what kind of radioistope contamination?

A

Xenon

71
Q

general public –> annual dose limit?

A

100 mrem

72
Q

Sv to rem –> conversion?

A

1 mSv = 100 mrem

73
Q

NRC occupation exposure dose limit?

  • total body dose per yr
  • ocular lens
  • organ (incl skin)
A
  • total body dose per yr: 5 rem (50mSv)
  • ocular lens: 15 rem (150 mSv)
  • organ (incl skin): 50 rem (500 mSv)
74
Q

NRC occupation exposure dose limit –> fetus over entire 9 mo?

A

0.5 rem (5 mSv)

75
Q

difference: recordable event vs reportable medical event? (2)

A

recordable event:

  • whole body dose <5 rem
  • organ dose <50 rem

reportable medical event

  • whole body dose >5 rem
  • organ dose >50 rem
76
Q

recordable event –> keep document –> how long?

A

5yr

77
Q

reportable medical event occurs –> next step?

A

notify:
- NRC
- ordering physician
- pt

78
Q

exposure rate?

  • radiation area
  • high radiation area
A
  • radiation area: 5 mRem/hr (0.05mSv)

- high radiation area: 100 mRem/hr

79
Q

what is target organ?

A

organ of interest –> want tracer to accumulate in

80
Q

what is critical organ?

A

organ –> inc susceptibility for cancer –> limit dose of radiopharmaceutical

81
Q

HIDA –> critical organ?

A

GB wall

82
Q

DMSA –> critical organ?

A

kidney

83
Q

pertechnetate –> critical organ?

A

stomach

84
Q

sulfur colloid –> critical organ?

  • IV
  • PO
A
  • IV: liver

- PO: prox colon

85
Q

sestamibi –> critical organ?

A

prox colon

86
Q

MAG3 –> critical organ?

A

bladder

87
Q

I-123 MIBG –> critical organ?

A

bladder

88
Q

I-131 MIBG –> critical organ?

A

liver

89
Q

gallium –> critical organ?

A

distal colon

90
Q

thallium –> critical organ?

A

kidney

91
Q

octreotide –> critical organ?

A

spleen

92
Q

In-WBC –> critical organ?

A

spleen

93
Q

damage RBC –> critical organ?

A

spleen

94
Q

1 advantage of SPECT over planar?

A

improved contrast from overlapping struct

95
Q

SPECT is depth-dependent –> T/F?

A

T

96
Q

PET is depth-dependent –> T/F?

A

F

97
Q

brain SPECT –> use what kind of collimator?

A

fan beam

98
Q

cardiac SPECT –> what is tuning fork artifact?

A

error w center of rotation (misregistration error) –> point source look like tuning fork

99
Q

SPECT vs PET –> match:

  • few cameras rotate around pt
  • set of complete rings/detectors around pt
A
  • SPECT –> few cameras rotate around pt

- PET –> set of complete rings/detectors around pt

100
Q

PET –> uses thicker crystal than SPECT –> T/F?

A

T

101
Q

PET: inc dose –> inc random coincidence –> T/F?

A

T

102
Q

PET: what is noise equivalent counts (NEC)?

A

ratio: true coincidences/total coincidences (true/true+false)

same as signal to noise ratio (SNR)

103
Q

PET: scintillator crystal –> which has best density/resolution/decay time? worst?

A
  • best –> lutetium oxyorthosilicate (LSO)

- worst –> bismuth germanate (BGO)

104
Q

PET: spatial resolution –> #1 limiting factor?

A

xl thickness

105
Q

PET: obese pt –> what can use to improve spatial resolution & image contrast?

A

time of flight

106
Q

time of flight PET vs standard PET –> is there a difference in SUV values?

A

time of flight –> higher SUV than standard PET

107
Q

contraindications for vasodilator pharmacologic stress? (2)

A
  • 2nd- or 3rd-degree atrioventricular (AV) block without a pacemaker
  • sick sinus syndrome
108
Q

antidote for adenosine?

A

Aminophylline

109
Q

F-18 FDG –> cardiac –> eval for?

A

cardiac viability

110
Q

Dipyridamole –> MOA?

A

indirect coronary artery vasodilator

111
Q

Exercise stress test –> need to reach heart rate of?

A

85% of age-predicted maximal heart rate

112
Q

what is transient ischemic dilation (TID)?

A

paradoxical phenomenon seen in myocardial perfusion SPECT imaging –> severe balanced coronary artery disease, myocardial ischemia may result in apparent enlargement of the left ventricular cavity during stress

113
Q

cardiac study –> Tc-99m tetrofosmin –> mech of uptake?

A

passive diffusion

114
Q

what is Roentgen?

A

measure of exposure to x-ray or gamma ray radiation. One roentgen is that amount of x-ray or gamma radiation that will deposit enough energy to liberate 1 electrostatic unit in 1 cubic centimeter of dry air.

115
Q

what is absorbed dose? unit?

A

amount of energy that ionizing radiation imparts to a given mass of matter

  • Gy
  • rad
116
Q

what is equivalent dose? unit?

A

dose equivalent relates the absorbed dose to the biological effect of that dose. The absorbed dose of specific types of radiation is multiplied by a “quality factor” to arrive at the dose equivalent

  • Sv
  • rem
117
Q

Tl-201 thallous chloride –> CNS lymphoma vs toxo?

A
  • lymphoma: pos

- toxo: neg

118
Q

Gastric emptying study - what is normal study?

A

4 hours –> 10% or less of initial activity should remain in the stomach