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Flashcards in Nucs basics Deck (50)
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1
Q

V/Q scan is rarely done in pregnancy

A

Only if CT can’t be done, and it should be with low dose

2
Q

When to image in In-111 leukocyte scan?

A

In-111 leukocyte imaging requires a blood draw on day 1 followed by same day reinjection. Images are typically acquired 24 hours after reinjection. Imaging within the 1st few hours after reinjection can lead to false-positive uptake in the lungs bilaterally.

3
Q

triple match in the upper or middle zones

A

low probability for PE

4
Q

triple match in the lower lung zone

A

Intermediate probability for PE, Non-diagnostic

5
Q

I-131 or I-123 metaiodobenzylguanidine (MIBG)

A

is a norepinephrine analogue incorporated in adrenergic storage granules.

6
Q

When is Axumin PET/CT indicated?

A

F-18 fluciclovine is indicated in patients who have been previously treated with radiation therapy or prostatectomy and present with biochemical recurrence.

7
Q

severe aortic stenosis, and family history of cardiac disease presents for myocardial perfusion imaging. Which of the following is the most appropriate stress modality?

A

Pharmacologic stress is preferred in patients with aortic stenosis because exercise stress is associated with hypotension, syncope, and sudden cardiac death. Dobutamine is contraindicated in patients with severe aortic stenosis. Vasodilator stress modalities such as regadenoson and persantine are preferred in this case.

8
Q

Which of the following structures shows hypometabolism on F-18-FDG PET in cases of Lewy body disease and not typically in other dementias?

A

Although there can be hypometabolism in all of the above regions in Lewy body dementia, the hallmark finding in this type of dementia is reduced glucose metabolism in the occipital lobe on F-18-FDG PET.

9
Q

When is bone scan indicated for Pagets disease?

A

When there’s suspicion for malignant transformation

10
Q

How to differentiate between Acute rejection and ATN by MAG3 scan?

A

By looking at the perfusion; ATN will have NORMAL perfusion and acute rejection will have decreased perfusion. BOTH will have DELAYED excretion.

11
Q

What’s uterine blush in nucs?

A

Fint uptake seen in the uterus in bone scan and meckle scan during the first 10 minutes. Observed in ALL phases of the menstrual cycle. NORMAL Finding.

12
Q

2ry osteosarcoma from Pagets looks on bone scan:

A

Photopenic lesion

13
Q

How Radionuclides can be produced in a nuclear reactor

A

by adding neutrons to a stable nuclide. Neutron activation products cannot be chemically separated, and are therefore not carrier free. (Nuclear reactor = Neutron added = Not carrier-free)

Then decay by beta minus process.

14
Q

How can Radionuclides be produced in cyclotrons

A

charged particles (e.g., protons) are added to stable nuclides.

Cyclotron-produced radionuclides generally decay by a beta plus or EC.

15
Q

Fission product radionuclides generally decay by

A

beta minus process, similar to neutron activation.

16
Q

In generators, when equilibrium is reached?

A

after four daughter half lives.

17
Q

What’s secular equilibrium?

A

when the parent is long lived.

In secular equilibrium, parent and daughter actives are exactly equal.

18
Q

What’s transient equilibrium?

A

when the parent radionuclide is short lived.

In transient equilibrium, parent and daughter actives are only approximately equal, and directly proportional to each other.

19
Q

What’s an example of active transport?

A

Thyroid uptake scanning with iodine (e.g., 123 I)

20
Q

What’s an example of compartmental localization?

A

Blood pool scanning can be performed with 99m Tc-labeled red blood cells

21
Q

What’s an example of compartmental leakage?

A

GI bleeding can be studied with 99m Tc-labeled red blood cells

22
Q

What’s an example of diffusion?

A

Kidney filtration can be assessed using 99m Tc-labeled DTPA

23
Q

What’s an example of phagocytosis?

A

Liver and spleen function can be assessed with 99m Tc-labeled sulfur colloid

24
Q

What’s an example of physicochemical adsorption?

A

bone scan

25
Q

What’s an example of cell sequestration?

A

Spleen scanning can use 111 In-labeled leukocytes

26
Q

What’s an example of receptor binding agent?

A

Neuroreceptor imaging can be performed with 18 F-labeled florbetaben

27
Q

What’s Detection efficiency in nucs?

A

the percentage of incident gamma rays totally absorbed in the scintillator (i.e., via photoelectric effect).

28
Q

What’s energy resolution?

A

aka Photopeak broadening.

expressed as a percentage of the photopeak energy,

Width of the 99m Tc photopeak (140 keV) in a 10 mm NaI crystal is about 14 keV, so the energy resolution is 10%

29
Q

Day-to-day measurements of the dose calibrator should vary by

A

Less than 5%

30
Q

Linearity is checked

A

quarterly by measuring the decay of 99m Tc over 72 hours.

  • Linearity can also be checked by using a source placed into cylinders of lead which attenuate the source by known amounts.
31
Q

How Corrections are made for nonuniformities

A

Nonuniformity corrections are computed from flood images obtained with a high number of counts to minimize random noise

32
Q

Gamma camera energy resolution is most likely checked:

A

Annually

Broadening of the photopeak is checked annually and is measured as the full width half maximum.

33
Q

What’s an example of a common iterative reconstruction algorithm used in SPECT?

A

Ordered subset expectation maximization (OSEM)

34
Q

What’s Low-pass filters in SPECT?

A

Low-pass filters remove the high frequencies, resulting in smoother (i.e., less noisy) images, but that have less distinct edges.

35
Q

What’s High-pass filters in SPECT?

A

High-pass filters will pass more high frequencies, resulting in sharper and noisier images that have enhanced edge definition.

36
Q

How frequent Photopeak window of the pulse height analysis (PHA) is evaluated

A

Daily

37
Q

What’s the limit for Nonuniformities checked by extrinsic flood test?

A

5%

Chcked daily with the collimator. (checks system performance)

38
Q

How frequent Center of rotation is performed?

A

Monthly.

“Residents do monthly rotations.”

39
Q

How’s Spatial resolution different between SPECT and planar imaging?

A

Spatial resolution of SPECT is always poorer than for planar imaging because SPECT images are derived from planar images.

40
Q

The major benefit of SPECT is

A

improved contrast that results from the elimination of overlapping structures.

Similar concet in radiography which has better resolution whereas cross sectional imaging has better contrast (MRI)

41
Q

Which PET detector has the best photoelectric absorption?

A

bismuth germanate (BGO)

But also has the worst energy resolution.

42
Q

What’s the difference between 2D and 3D PET imaging?

A

In 2D mode, coincidences are detected within each individual ring of detectors, but not between adjacent rings

In 3D mode, septal collimator rings are not used

43
Q

What’s Fourier rebinning in PET?

A

is used to rebin 3D data into 2D data sets.

44
Q

Breastfeeding cessation is not needed for

A

FDG-18

45
Q

Daily surveys are required in areas where

A

written directive procedures are carried out. like 131-I therapy.

46
Q

How’s spatial resolution of 82Rb images compared to FDG?

A

Spatial resolution of 82 Rb is worse than 18 F because the 82 Rb positron travels further

47
Q

An ideal radionuclide for therapeutic nuclear medicine application would most likely only emit:

A

Beta minus

48
Q

In NM, personnel must be provided with a dosimeter when their occupational dose may exceed ______% of a regulatory dose limit.

A

10%

49
Q

What technical differencee between 18F-Fluciclovine and FDG?

A

In fluciclovine, image acquisition starts immediately after injection and it begins from pelvis upwards. The reason is to avoid any excretion of radiotracer into bladder that might obscure the prostate.

50
Q

Most likely cause of diffuse thyroid uptake on FDG PET?

A

Autoimmune thyroditis.