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Cara and Jason's Flashcards > Nucs Cara flashcards > Flashcards

Nucs Cara flashcards

1
Q

What is the appropriate protocol for receiving radioactive packages?

A

Survey and wipe test within 3 hours of receipt during workhours or from begining of business opening

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2
Q

What is the (external) wipe test limit?

A

2200 dpm/100cm^2 (6600 dpm/300cm^2)

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3
Q

What are the handling requirements for radioactive white I package label and what are its radiation limits?

A

No special handling; Surface < 0.005 mSv/hr (0.5 mrem/hr); 0 @ 1 meter

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4
Q

What are the handling requirements for radioactive yellow II package label and what are its radiation limits?

A

Special handling; surface < 0.5 mSv/hr (50 mrem/hr); < 0.01 mSv/hr (1 mrem/hr) @ 1 meter

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5
Q

What are the handling requirements for radioactive yellow III package label and what are its radiation limits?

A

Special handling; surface > 0.5 mSv/hr but < 2 mSv/hr (200 mrem/hr); < 0.1 mSv/hr (10 mrem/hr) @ 1 meter

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6
Q

On a radiation package, what deos TI stand for?

A

Transportation Index

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7
Q

What does TI measure/how is it measured?

A

Dose rate at the time of shipping measured with a G-M counter representing number of mrem/hr @ 1 meter

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8
Q

Which radioactive package label does NOT have a TI listed?

A

White I because TI will be zero

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9
Q

A yellow III package indicates a TI of at least how much radiation?

A

> 0.01 mSv/hr (or 1 mrem/hr) @ 1 meter

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10
Q

How long must records be kept for regulatory purposes?

A

Licensee must keep radiation protection program records for 3 years

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11
Q

What is the occupational radiation dose limit for a radiation worker?

A

50 mSv/year

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12
Q

What is the dose limit for a fetus in a radiation worker?

A

5 mSV during term (or 0.5 mSv/month)

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13
Q

What is the lens radiation dose limit?

A

150 mSv/year (more updated limit is 20 mSv/year)

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14
Q

What is the extremity and single organ radiation dose limit?

A

500 mSv/year

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15
Q

What is the nonoccupational/general public radiation dose limit for frequent and infrequent exposures?

A

Frequent: 1 mSv/year (or 0.02 mSv/hr). Infrequent: 5 mSv/year

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16
Q

What is an unrestricted area?

A

Area not controlled by radiation safety officer due to low levels of radiation; Examples include the waiting room, file room, office, nonradiation lab

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17
Q

What are the different levels of restricted areas?

A

Radiation area, high radiation area, and very high radiation areas

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18
Q

What is the dose limit in an unrestricted (uncontrolled) area?

A

Must be < 0.02 mSv/hr (and < 1mSv/7 consecutive days; or < 5 mSv/year) => Think frequent general public radiation exposure limits

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19
Q

What is a restricted area?

A

Occupational exposure area under supervision by the radiation protection officer due to certain levels of radiation exposure

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20
Q

What is the dose threshold for a restricted (controlled) area?

A

> 0.02 mSv/hr (and > 1 mSv/7 consecutive days or 50 mSv/yr) => Think occupational radiation exposure limits

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21
Q

What radiation level defines a “radiation area”?

A

Possible excess of 0.05 mSv/hr @ 30 cm

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22
Q

What radiation level defines a “high radiation area”?

A

Possible excess of 1 mSv/hr @ 30 cm

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23
Q

When are personal dosimeters needed?

A

Used on individuals who are likely to receive in excess of 10% of the allowable occupational dose limits.

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24
Q

What does CFR 19 cover?

A

Inspections

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25
Q

What does CFR 20 cover?

A

Radiation worker protection

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26
Q

What does CFR 35 cover?

A

Medical uses of radioisotopes

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27
Q

What detector is sensitive but cannot handle high radiation doses?

A

Geiger-Mueller counter

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28
Q

How often should a Geiger-Muller counter be calibrated?

A

Annually

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29
Q

What is the max dose of a Geiger-Mueller counter can reliably detect?

A

100 mR/hr

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30
Q

What does a Geiger-Mueller counter detect?

A

Alpha, beta, gamma, etc. radiation

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31
Q

How does an ionization chamber differ from a G-M counter?

A

An ionization chamber can handle higher radiation levels

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32
Q

In what setting is a well-counter used, which has a mid-level sensitivity between G-M and ionization chamber and is therefore good for medium amounts of radiation?

A

For wipe tests

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33
Q

How does a well counter work?

A

It s a single photomultiplier tube, i.e. it uses a scintillation crystal.

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34
Q

Why do you have to specify what radionuclide is in the dose calibrator?

A

Some radionuclides have multiple gamma emissions per decay which would alter apparent activity unless the computer expects this

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35
Q

How often is dose calibrator constancy assessed?

A

Daily; max error +/-5%

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36
Q

What do you use for contancy testing?

A

Co-57 (2-5 mCi, 122 keV, 270 day half-life) or Cs-137 (100-200 uCi, 662 keV)

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37
Q

How often is dose calibrator linearity assessed?

A

Quarterly; max error +/-5%

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38
Q

What does linearity mean?

A

Accurate readings over a whole spectrum of activity levels (high to low)

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39
Q

How often is dose calibrator accuracy assessed?

A

Annually; max error +/-5%

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40
Q

What is accuracy?

A

Measuring a dose on the machine gives a reading in mCi equivalent to what the known standard value should read

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41
Q

How often is dose calibrator geometry assessed?

A

Upon repair or when the unit is moved; max error +/-5%

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42
Q

What is geometry?

A

Potential differences in measuring counts in a vial (which is placed at the bottom of the well) versus syringe (in the syringe holder higher up in the well)

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43
Q

Do dose calibrators contain sodium iodine scintillation crystals?

A

No

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44
Q

How often is extrinsic gamma camera uniformity assessed?

A

Daily with a flood

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45
Q

What is the upper limit of non-uniformity?

A

2-5% on a gamma camera or must be <1% on SPECT

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46
Q

What is the difference between intrinsic versus extrinsic uniformity?

A

Intrinsic is without a collimator; extrinsic is with the collimator.

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47
Q

How often is intrinsic uniformity tested?

A

Weekly with a point source, collimator removed.

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48
Q

What do you use to perform uniformity testing?

A

A Tc-99m water mixture (tank for extrinsic, less common, more problems; syringe “point” source for intrinsic) or a Co-57 flood source (sheet for extrinsic or point source for intrinsic)

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49
Q

What are the components that effect uniformity

A

Detector uniformity of response (intrinsic uniformity), collimator integrity (extrinsic uniformity), and the quality of the analog/digital signal conversions at the camera–computer interface

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50
Q

What is the most common non-uniformity artifact in SPECT?

A

Ring artifact

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51
Q

How often is the gamma camera photopeak calibrated?

A

Daily, automatic on the camera

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52
Q

How often is gamma camera spatial resolution and image linearity (not energy linearity) checked?

A

Weekly

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53
Q

What is used to perform weekly spatial resolution and image linearity gamma camera testing?

A

Quadrant bar phantom between the detector and a Co-57 sheet

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54
Q

What is the difference between spatial resolution and image linearity in the context of the quadrant bar phantom test?

A

Linearity: lines are straight versus spatial resolution: distinguishing individual small lines

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55
Q

How often is gamma camera center of rotation testing performed?

A

Weekly

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56
Q

If center of rotation is off, what is a classic resulting artifact?

A

Donut artifact (360 degree rotation, point source); tuning fork artifact (180 degree rotation)

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57
Q

What energy range defines a low energy collimator?

A

< 200 keV

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58
Q

What radionuclides use a low energy collimator?

A

Tc-99m, I-123, Xe-133, and Tl-201

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59
Q

What energy range defines a medium energy collimator?

A

200-400 keV

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60
Q

What radionuclides use a medium energy collimator?

A

Ga-67 and In-111

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61
Q

What energy range defines a high energy collimator?

A

> 400 keV

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62
Q

What radionuclides use a high energy collimator?

A

I-131

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63
Q

In comparing high versus low energy collimators, describe the septa height and spacing?

A

High energy: long thick septa with widely spaced holes (spacing counter balances septa construction preserving some sensitivity); Low energy: short thin septa closely spaced (spacing preserves resolution in light of sensitive septa contruction)

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64
Q

What is the most commonly used collimator?

A

Low energy and high resolution

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65
Q

What is the point of a callimator?

A

Obtain spatial localization

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66
Q

In contradistinction, how does PET obtain spatial localization?

A

Coincident registration

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67
Q

How would a collimation defect appear on a gamma camera?

A

Linear defect

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68
Q

Describe the porportionality between the sensitivity of the collimator to spatial resolution of the collimator?

A

Inversely proportion

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69
Q

When might a highly sensitive collimator be important to use?

A

In short imaging time sequences such as dynamic imaging

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70
Q

What is the effect of distance on sensitivity versus spatial resolution?

A

Distance does NOT effect sensitivity (despite inverse square law more of the body is included in the detector s field of view so net counts is unchanged); distance DECREASES spatial resolution

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71
Q

Where should the collimator-detector be placed in relation to the patient (far or close)?

A

As close as possible

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72
Q

What effect on spatial resolution does moving closer to parallel hole collimator do?

A

Increases resolution

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73
Q

What is star artifact and why does it occur?

A

Star artifact looks like beams emanating from a hot spot; occurs due to septal penetration of high energy gamma rays due to inappropriately low energy collimator being used, especially happens when imaging I-131 post-treatment thyroid bed

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74
Q

What happens when your gamma camera window is too wide?

A

Terrible image due to image inclusive of scatter

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75
Q

What happens when your pulse height analyzer is incorrect?

A

Too much scatter!

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76
Q

What is one advantage of dual head gamma camera?

A

Decreased scan time

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77
Q

What is the advantage of SPECT over planar gamma camera?

A

Better contrast resolution (due to less overlap of tissues)

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78
Q

What is an approximate estimate of the sensitivity of PET in comparison to SPECT?

A

PET is 10-20x more sensitive

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79
Q

Regarding the appearance of the scan, what organs are hotter on the non-attenuation corrected images?

A

Skin and lungs

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80
Q

What is the difference between 2D and 3D PET?

A

2D excludes scatter using septa in addition to coincident timing; 3D excludes scatter by coincident timing along

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81
Q

What is the purpose of time-of-flight in PET?

A

Improve spatial resolution and contrast

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82
Q

What is normalization testing for PET?

A

Normalizes detectors using point source

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83
Q

How often is normalization performed?

A

Monthly

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84
Q

How often does a “blank scan” need to be performed?

A

Daily

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85
Q

What is a “blank scan” used for and how is it performed?

A

Used to zero the scanner using the scanner s own transmission source; nothing is in the scanner when it s performed

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86
Q

How are SUV values effected in an obese person?

A

SUV values are falsely high, i.e overestimated. Using lean body mass can be used to overcome this limitation

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87
Q

In the case of truncation of CT data due to an extremely large person partially outside the field of view, how will this effect SUV?

A

Falsely lower SUVs, in contradistinction to the above abberation in SUV

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88
Q

What is the effect of when an FDG-PET scan is performed, i.e. time since injection of FDG?

A

Increasing SUV values over time when scanned later (e.g. @ 1 hour SUVs will be lower than @ 2 hours; increases to a point obviously limited by half-life)

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89
Q

What is the molybdenum breakthrough limit in a molybdenum-technetium generator?

A

0.15 uCi Mo/1 mCi Tc at the time of administration (amount of Mo @ time of elution does NOT matter); holds true also for 0.15 kBq Mo/1 MBq Tc

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90
Q

Which is assessed for first in Mo breakthrough testing, Mo or Tc?

A

Molybdenum

91
Q

What are the gamma emmisions of Mo?

A

181, 740, 780 keV

92
Q

When is Mo breakthrough measured?

A

With EVERY generator elution; due to longer Mo half-life in comparison to Tc, an elution that is Mo breakthrough compliant may no longer be compliant @ the time of administration, hence why time of administration is key in this regulation

93
Q

What are the radiochemical purities mandated?

A

>95% for Tc-pertechnetate, >92% for Tc-MAA and >91% for other Tc agents

94
Q

How do you test for radiochemical purity?

A

Thin Layer Chromatography

95
Q

What does TLC detect?

A

Free tecnetium

96
Q

Where is the free tech on TLC?

A

Front on the acetone and origin on saline

97
Q

What is a stannous ion?

A

Tin (II)

98
Q

What is a stannous ion used for?

A

To reduce free pertechnetate from +7 valence state at elution to a lower valence state to allow binding of the radionuclide to a chemical

99
Q

How do unwanted radiochemical impurities occur?

A

Insufficient stannous ion (Tc not reduced sufficiently), accidental air injection (stannous ion is oxidized to stannic ion by oxygen or sometimes water) or exposure to saline preservatives (hydrolyzed-reduced Tc)

100
Q

What has to happen before Tc-99m can be conjugated to RBC?

A

It must be reduce with stannous ion, also called tinning

101
Q

How can EXCESS stannous ion appear?

A

For example, unexpected liver activity in a bone scan

102
Q

What does pyrogen testing assess for and how it is performed?

A

Endotoxin impurities tested by limulus amebocyte lysate test

103
Q

What is the aluminum breakthrough limit for an elution of Tc-99m?

A

Must be <10 ug/mL, performed on every elution

104
Q

Aluminum testing is what kind of purity?

A

Chemical

105
Q

What test is performed when doing chemical purity testing for Al?

A

pH

106
Q

What causes clumped hot spots in the lungs on a liver/spleen (sulfur colloid) scan?

A

Too much aluminum in the Tc-99m

107
Q

When is 95% maximum activity for Mo/Tc generator reached?

A

24 hours after last elution

108
Q

What does equilibrium mean with regard to a parent/daughter isotope?

A

When the activity of the daughter is equal to the parent

109
Q

What is transient equilibrium?

A

When the half-life of daughter < parent. For example, in the case of Mo/Tc generator, transient equilibrium is reached in 4 half-lives. Activity of the daughter slightly exceeds parent @ equilibrium in a “transient equilibrium” relationship. At this point, both start to slightly decrease in activity.

110
Q

What is secular equilibrium?

A

Half-life of daughter <<< parent, so the activity of the daughter approaches the parent and stays level

111
Q

What is effective half-life, how is it calculated and how does it compare to physical or biologic half-lives?

A

Accounts for both physical and biologic half-lives; 1/Te=1/Tp+1/Tb; Te is always less than the smaller of either Tp or Tb.

112
Q

Which are usually carrier free, isotopes created by neutron bombardment or by cyclotron production?

A

Cyclotron produced radionuclides

113
Q

Are fission products known for being carrier free?

A

Yes

114
Q

How do isotopes differ from one another?

A

Same protons but different neutrons

115
Q

How do isomers differ?

A

Different energy, but same number of protons and neutrons

116
Q

How do isotones differ?

A

Same number of neutrons but different protons and different atomic number

117
Q

How do isobars differ?

A

Same atomic number (protons + neutrons) but different numbers of protons and different numbers of neutrons

118
Q

What is the most a dose can differ from the prescribed radioactive dose?

A

20% (10% in some agreement states)

119
Q

What qualifies as a medical event and needs to be reported?

A

1) Wrong patient, wrong radiopharmaceutical, wrong route, wrong dose (>20%) or dose to wrong site of body resulting in >50% excess to the body part than otherwise expected for appropriate administration AND (must ALSO result in) 2) HARM to the patient, i.e. a whole body dose > 50 mSv or organ/extremity dose > 500 mSv

120
Q

If the “harm to the patient” dose levels are not met, what then?

A

It is a recordable but not reportable event

121
Q

What do you have to do in a medically reportable event?

A

Call the referring doctor, call the NRC/state if agreement state, call the patient, write a letter to the NRC within 15 days

122
Q

What do you have to do for a recordable event?

A

Keep record for 3 years; institutional review

123
Q

How many days are given to submit a written report to the NRC when a medical event occurs?

A

15 days

124
Q

What is a MINOR spill?

A

< 100 mCi of Th-201 or Tc-99m; < 10 mCi Ga-67, In-111, I-123; < 1 mCi I-131

125
Q

What is a MAJOR spill?

A

> 100 mCi of Th-201 or Tc-99m; > 10 mCi Ga-67, In-111, I-123; > 1 mCi I-131

126
Q

What do you have to do for a minor spill?

A

Clean it up

127
Q

What do you have to do for a major spill?

A

Don t clean it up; Call the radiation safety officer

128
Q

How long do you have to keep radioactive waste?

A

Approximately 10 half-lives i.e. when indistinguishable from background radiation

129
Q

What is the frequency of an ambient radiation survey?

A

Daily, end of the work day

130
Q

Name two radionuclides made with generators?

A

Tc-99m and Rb-82

131
Q

When is a writtern directive from the authorized user required?

A

Anytime >30 uCi of I-131 is administered or any therapeutic radioactive material

132
Q

Written instructions are given to a patient after being dosed with I-131 given the possible radiation exposure to others with the goal of the patient keeping exposure to others below certain threshold to the general public. What is this level?

A

Written instructions given to the patient on avoiding others if the potential exists for an exposure in excess of 1 mSv to the general public.

133
Q

What are the threshold levels for release after therapeutic I-131 administration?

A

The patient may be released when any one is met 1) A calculated level of potential exposure to other people is < 5 mSv to any individual 2) Actual activity measures < 0.07 mSv/hr @ 1 meter (< 7 mrem/hr) measure by a G-M counter or 3) An oral dose of < 33 mCi was administered.

134
Q

Are outpatients actually measured before they leave our department?

A

Not if the expected (calculated) exposure is < 5mSv to any individual

135
Q

Is there a dose limit to the caregiver of an individual who received I-131?

A

No regulated dose limit for caregiver, only that which does not cause health problems.

136
Q

On average, how much higher is a retreatment dose of I-131 in comparison to the initial dose?

A

50% higher

137
Q

When is recombinant TSH used (thyrogen)?

A

Pre-treatment with I-131 to prime uptake

138
Q

What radiotracers can you use to perform thyroid imaging?

A

Tc-99m pertechnetate and I-123; I-131 less commonly but done sometimes in preparation for; imaging is always does after I-131 treatment which uses the gamma rays emitted by I-131

139
Q

How does the thyroid treat Tc-pertechnetate versus Iodine?

A

Technetium pertechnetate is trapped but not organified; Iodine is trapped and organified.

140
Q

What is normal thyroid uptake on I-123 or I-131?

A

10-30% @ 24 hours

141
Q

What scan most effectively images medullary thyroid CA?

A

In-111 pentetriotide (and second to that FDG-PET)

142
Q

What is suspected if you see brain or kidneys in the perfusion portion of a V/Q scan?

A

Right to left shunt is present (in the heart or lungs)

143
Q

What radiopharmaceuticals can be used for V/Q?

A

Xe-133 gas or Tc-99m DTPA for ventilation; Only Tc-99m MAA for perfusion.

144
Q

With what radiotracer can you do ventilation washout imaging?

A

Only Xenon

145
Q

What criteria are used to assess V/Q scans for PE?

A

Modified PIOPED II

146
Q

How do you diagnose a PE using the modified PIOPED II criteria?

A

Using the modified PIOPED II criteria, two or more large V/Q mismatches are needed to make a determination of PE present. There are limited specific criteria used to make a determination of PE-absent (very low probability or a normal scan). All other findings are nondiagnostic.

147
Q

What renal agents are used for functional imaging and what are used for structural imaging?

A

DTPA and MAG3 for function; DMSA for structure

148
Q

What is the appearance of pyelonephritis on a renal scan?

A

Perfusion on a functional renal scan can be normal; focal or diffuse photopenic defect may be seen in structural renal imaging

149
Q

How will ATN appear on functional renal imaging?

A

Normal perfusion but poor excretion

150
Q

When is lasix given and why?

A

20 minutes into a functional renal scan in the setting of retained tracer in the renal pelvis (i.e. obstruction versus dilated collecting system)

151
Q

Why is an ACEi given in specific renal scans?

A

To assess for renal artery stenosis

152
Q

What would be seen in an ACEi provocation renal scan?

A

Delayed perfusion of a kidney with prolonged retention

153
Q

Describe the liquid gastric emptying curve.

A

Liquid empties exponentially

154
Q

What is the cause of a medially displaced liver from the ribs on sulfur-colloid scan?

A

Ascites usually in the setting of chronic liver dysfunction (cirrhosis)

155
Q

Name the intrathecal radiotracers.

A

In-111 DTPA or Tc-99m DTPA.

156
Q

Which is preferred, an exercise or pharmacologic stress test?

A

Exercise

157
Q

What medications can be used in a pharmacologic stress test?

A

Vasodilators (dipyridamole, adenosine, or regadenson) or dobutamine

158
Q

What are the contraindications to vasodilator stress tests?

A

Severe obstructive airway disease, high-grade heart block (2nd- or 3rd-degree atrioventricular (AV) block without a pacemaker or sick sinus syndrome), arterial hypotension, recent caffeine ingestion, or dipyridamole or theophylline containing medications.

159
Q

What are the contraindications for dobutamine stress tests?

A

Cardiac issues (e.g. critical aortic stenosis, hypertrophic cardiomyopathy, uncontrolled hypertension, uncontrolled atrial fibrillation, known severe ventricular arrhythmias) and disorders in potassium homeostasis

160
Q

Concerning vasodilators, what are the indications for stress testing?

A

Patients who are taking a beta blocker, calcium channel blocker, or have a pacemaker and cannot achieve the required target heart rate (85% of maximum predicted heart rate) should undergo a pharmacologic stress in lieu of an exercise stress.

161
Q

What is dipyridamole?

A

Inhibits breakdown of adenosine, indirectly causing vasodilatation through prolonging lifespan of endogenous adenosine

162
Q

What is regadenoson?

A

Selective A2a receptor agonist, which is a vasodilator

163
Q

What is the antedote to adenosine and/or dipyridamole?

A

Aminophylline (caution: its half-life is shorter than dipyridamole)

164
Q

What is dobutamine?

A

Beta 1 agonist increasing heart rate and contractility (chronotrope and inotrope)

165
Q

When is dobutamine contraindicated?

A

Severe aortic stenosis

166
Q

What medication is contraindicated for a dobutamine stress?

A

Beta-blockers (would block it s action)

167
Q

How do you reverse dobutamine?

A

Beta-blockers

168
Q

What is the signficance of normal wall motion with an apparent perfusion defect?

A

Think something other than ischemia (e.g. artifact like attenuation)

169
Q

Where does the breast classically cause attenutation defects?

A

Anterior or lateral wall

170
Q

How would left bundle branch block present on a myocardial perfusion test?

A

Can cause a false-positive reversible septal perfusion defect with exercise; therefore a pharmacologic stress is preferred.

171
Q

What is the reason for an apparent defect when there is adjacent extra-cardiac activity (e.g. inferior wall defect with adjacent liver/bowel activity?

A

It is the result of filtered back projection using a ramp filter

172
Q

A similar result is seen due to the diaphragm but the diaphragm is not hot unlike liver/bowel. Why does this occur?

A

Attenuation; overcome by attenuation correction or prone imaging

173
Q

What does transient ischemic dilatation (TID) suggest?

A

Severe or multivessel disease

174
Q

What is the TID cutoff ratio?

A

1.4

175
Q

What would be a cause of apparent left ventricular wall divergence toward the apex with an apical defect?

A

Left ventricular aneurysm

176
Q

Which has less attenuation, Th or Tc cardiac studies?

A

Tc due to higher energy gamma rays

177
Q

Which requires active transport into cells, Th or Tc cardiac agents?

A

Th (N/K ATPase pump) versus Tc agents rely on passive diffusion into mitochondria

178
Q

Which needs to be imaged immediately after injection (in the stress portion of a study)?

A

Th because it redistributes; Tc images acquired 30-90 minutes after (lungs back to nl volume, liver activity cleared but not yet to transverse colon)

179
Q

What does a matched true defect represent on a Tc cardiac study?

A

Either infarct or hibernating myocardium

180
Q

In a cardiac PET, what does F-18 FDG uptake in an area of absent myocardial perfusion suggest (such as seen previously on Tc-Sestamibi)?

A

Anaerobic utilization of the radioactive glucose due to viabile myocardium in the setting of hibernating myocardium (i.e. NOT infarct)

181
Q

How do you calculate EF for a MUGA?

A

(ED counts-ES counts)/(ED counts-background counts) x 100 = %

182
Q

What background activity will make EF falsely HIGH on MUGA?

A

High background

183
Q

What background activity will make EF falsely LOW on MUGA?

A

Low background

184
Q

Inclusion of what organ can commonly falsely alter background counts in a MUGA study?

A

An error can occur if the processing includes counts from the spleen.

185
Q

On a MUGA scan, drawing the background ROI over the spleen will do what?

A

Falsely elevated EF

186
Q

What classically causes a photopenic halo on a MUGA?

A

Pericardial effusion

187
Q

What medication is used for cerebrovascular reserve?

A

Acetazolamide

188
Q

What does an acetazolamide cerebral flow reserve study distinguish?

A

Vascular versus another cause of dementia

189
Q

How is a balloon occlusion test performed for cerebral flow reserve testing?

A

The carotid is occluded to evaluate for collateral cerebral blood flow/reserve; if sx occur inject Tc immediately, if no sx occur inject 5 min prior to deflation of the balloon.

190
Q

What two scans are useful in sarcoid?

A

Ga-67 and FDG-PET

191
Q

What s the sign associated with sarcoid in the chest on Ga-67?

A

Lambda sign

192
Q

After intraarterial injection of Y-90 theraspheres, what imaging is done?

A

Brehmstralung liver imaging to evaluate for lung shunt fraction, a potential contraindication to treatment

193
Q

What does Y-90 emit?

A

Beta particles (negatively charged electrons)

194
Q

What then creates the brehmstralung radiation in a Y-90 Brehmstralung scan?

A

The electrons by brehmstralung interactions in the patient forming x-rays

195
Q

What scans are helpful in distinguishing CNS toxoplasmosis from CNS lymphoma?

A

Th-201 and Ga-67: Toxoplasmosis will be cold on Th but hot on Ga (Similar to PCP/PJP); Lymphoma will be hot on Th AND Ga (Unlike Kaposi s which is hot only on Th but cold on Ga).

196
Q

What agent/agents could be used for ictal imaging?

A

Tc-99m ECD or HMPAO, lipophilic brain agents

197
Q

Which is more sensitive a test, ictal or interictal?

A

Ictal

198
Q

What might the underlying pathology be when increased soft tissue uptake is seen in the lower extremity (one or both) on a bone scan?

A

Diffuse lymphedema or IVC obstruction

199
Q

You see a solitary lesion in rib or elsewhere on PET for mets. Is it a met or not?

A

Likelihood of a met is 15-20% of cases overall. If it were actually a met, usually it would be in the spine. < 10% of the time does it represent a met when the solitary lesion is in a rib and usually these are more longitudinally oriented in the rib.

200
Q

Significance of heart activity on bone scan?

A

amyloidosis, myocarditis, pericarditis, prior myocardial infarction, or previously administered radiopharmaceutical.

201
Q

What scans should be considered in the setting of an orthopedic prosthesis when the ddx is infection versus aseptic loosening?

A

Tc-99m sulfur colloid (to look for normal marrow, cold in infx), Tc-99m MDP (non-specific for any reactionary change but helpful if totally negative), and Indium-111 (hot in normal marrow or infection, helpful? maybe in septic arthritis)

202
Q

What are distinguishes peri-prothetic infection versus loosening?

A

Both appear hot on Indium-111 oxime WBC scan, but only aseptic loosening will be hot on Tc-99 sulfur colloid. Bone scan hot in either, so only helpful if cold ruling out both etiologies as source of pain.

203
Q

What does prominent renal cortical activity on a bone scan suggest?

A

Hemochromatosis

204
Q

What don t you see in a superscan?

A

Kidneys and bladder (also less soft tissue)

205
Q

What are the causes of a superscan?

A

Diffuse mets (prostate and breast, skull possibly not as stunningly hot) or metabolic (hyperparathyroidism, Paget s, thyrotoxicosis, and renal osteodystrophy; skull markedly hot)

206
Q

What is Prostacint?

A

In-111 capromab which is an antibody to PSA, does NOT pick up bone mets, used AFTER bone scan to look for soft tissue mets

207
Q

What are the three radiopharmaceuticals used for therapeutic reasons for bone pain caused by mets?

A

Sr-82 (Strontium)-Chloride [Metastron, pure beta emitter, high myelotoxicity, 50 DAY half life], Sa-153 (Samarium)-EDTMP [Quadramet, beta and gamma emitter, transient bone marrow suppression, 46 hour half life], and Ra-223 (Radium)-dichloride [Xofigo, alpha emitter and minimal gamma, GI excretion rather than renal, less hematologic toxicity although more diarrhea/nausea/vomiting/bone pain, 64 hour half life]

208
Q

Which therapeutic radiopharmaceutical improves survival?

A

Ra-223 dichloride

209
Q

Absolute contraindications for treatment with Sr-82 or Sa-153?

A

For Sr 82-Cl and Sa 152-EDTMP: pregnancy, breast feeding, and GFR <30, and possibly extensive (superscan level) mets [although this is controversial]

210
Q

What scans are known for having a hot spleen?

A

In-111 WBC and In-111 pentetriotide scans (Both In-111 scans!)

211
Q

What does renal uptake on a liver/spleen scan suggest?

A

CHF

212
Q

What does renal transplant uptake on a liver/spleen scan suggest?

A

Rejection

213
Q

How might renal cancer activity on PET appear?

A

Variable, can be hypermetabolic but known for being HYPOmetabolic. For instance, an oncocytoma is known for being hot and clear cell RCC is known for being cold.

214
Q

What is peculiar about a lymphoscintigraphy study (i.e. how does it look)?

A

Co-57 flood source behind patient, soft tissues photopenic, nodes hot

215
Q

What is the radiotracer of choice for neuroblastoma imaging?

A

I-123 MIBG

216
Q

What is the radiotracer of choice for pheochromocytoma imaging?

A

I-123 MIBG

217
Q

What is Lugol s solution?

A

Potassium iodide

218
Q

Why is Lugol s solution given?

A

To suppress thyroid uptake

219
Q

When is Lugol s solution used?

A

Prior to I-123 MIBG scan

220
Q

What does a salivagram detect?

A

Aspiration; a salivagram is DIFFERENT than salivary gland scintigraphy (parenchymal and excretory function of glands)

221
Q

What is dacryscintigraphy?

A

Tc-99m pertechnetate drops in the eye; normal flow into nasal cavity if nasolacrimal duct not occluded at medial canthus

222
Q

What is the rate of bleeding necessary for detection on angio and on a GI bleeding scan?

A

Angio: 1 mL/min. Tagged RBC: 0.1 mL/min.

223
Q

At what size should a PET/CT be considered in the evaluation of a solitary solid pulmonary nodule?

A

> 8 mm

224
Q

What is the spatial resolution limit of PET?

A

5-8 mm

Cara and Jason's Flashcards (8 decks)

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