Nucs

Question 1

Mo-99 is the mother isotope for elution of Tc-99m

what is used to test for breakthrough in the eluate?

Answer 1

Dose calibrator

When eluting a Tc-99m generator, the mother isotope Mo-99 can contaminate the eluate. It is required to test for Mo-99 breakthrough in each eluate

Question 2

what effect does glucagon have on peristalsis and vasodilation?

Answer 2

decreases peristalsis and increases vasodilation

Question 3

What is the T_1/2 of Rb 82, what is it used for

Answer 3

Rb-82 is used as a cardiac perfusion agent and produced from a Sr-82/Rb-82 generator. The physical half-life of Rb-82 is 75 seconds.

Question 4

History of thyroid cancer, elevated thyroglobulin and negative I₁₃₁ whole body survey. What exam can you do?

Answer 4

PET can be used to look for mets

Question 5

what is the critical organ in a hepatobiliary scan?

Answer 5

gallbladder wall

Question 6

If you double your matrix size by how much does your # of pixels increase?

Answer 6

4x

Remember that the smaller the pixel the less counts per pixel which increase STN

Question 7

What type of scan?

Answer 7

Octreoscan

avid lesion in the pancreas

most likely islet cell tumor like gastrinoma or insulinoma

could also be carcinoid (more rare)

Question 8

21M without trauma

Answer 8

Osteosarcoma.

with MR to help we see soft tissue extension and cortical breakthrough

Ewing and other small round blue cell tumors are also in diffx (or smoldering infx) but less likely based on age

Question 9

dipyramidole mechanism of action?

Answer 9

Indirect vasodilator for coronary arteries

acts via preventing reuptake and deamination of adenosine—> increases tissue levels of adenosine

Question 10

Which drug limits release of pertechnetate by gastric mucosal cells and thus enhances sensitivity for meckel’s scan?

Answer 10

cimetidine (H2 blockers)

Question 11

Answer 11

Superscan 2/2 prostate mets

Metabolic superscans usually affect entire skeleton while metastatic are more likely to be axial and proximal appendicular skeleton

breast and prostate most likely to cause superscan

Question 12

what drug causes dose related increase in heart rate, blood pressure, and myocardial contractility?

Answer 12

Dobutamine

direct B1 and B2 activity

Dobutamine increases regional myocardial blood flow

secondary pharmacologic stressor, recommended only in patients who cannot undergo exercise stress and who also have contraindications to pharmacologic vasodilator.

Question 13

what med changes might you make before a ₁₃₁I- NaI (sodium iodide) scan after ablation/treatment for thyroid cancer?

Answer 13

either decrease dose of levothyroxine (to increase endogenous TSH) or give thyrotropin alpha

Question 14

What is the half life of Xe133?

Photon Energy?

Answer 14

5.3 days

gamma energy: 81 keV

Question 15

What measures the biological damage caused by ionizing gamma radiation exposure?

Answer 15

Roentgen equivalent man

—> REM

term for dose equivalence, equals the biological damage that would be caused by 1 radiation absorbed dose (RAD). The REM accounts for the fact that not all types of radiation are equally effective in producing biological change or damage. That is, the damage from 1 RAD deposited by beta radiation is less than that caused by 1 rad of alpha radiation.

Question 16

Half life of Thallous Chloride?

TI-201

Answer 16

73 hours

Question 17

Dose calibrator has what checked on installation or anytime it is moved?

Answer 17

Geometry

Geometry assesses the effect of sample volume &/or configuration in a vial or syringe on the measurement of a sample’s activity.

Question 18

What are the advantages of In III WBC vs Tc99m HMPAO for infection/inflammation?

Answer 18

Tc-99m HMPAO labeled leukocyte scintigraphy: advantages of earlier and shorter imaging times, lower absorbed radiation dose, and a smaller blood sample for labeling leukocytes.

In-111 leukocyte scintigraphy: preferred in the abdomen/pelvis, because there is normally no excretion into gastrointestinal or urinary tracts. (Fewer false positives)

Question 19

Half life of Sodium Fluoride F18

Answer 19

109 minutes

Same as F18 used for PET (with FDG label)*

Question 20

Mechanism of action Tc99m Tetrofosmin

Answer 20

Passive diffusion

amount delivered to myocytes is 2/2 perfusion

Question 21

What radiotracer used to evaluate renal cortex?

Answer 21

Tc99m DMSA

Renal cortical imaging—differentiates scar from pyelonephritis

DMSA works by tubular (cortical) binding

Question 22

Half life of I₁₃₁ NaI

I₁₂₃?

Answer 22

I ₁₃₁ = 8 days, 364 keV

I₁₂₃ = 13 hours, 159 keV

Question 23

Answer 23

Sacral insufficiency fracture

2/2 normal force applied to demineralized bone

Causes: postmenopausal osteoporosis, disuse osteopenia, steroids, metabolic bone disease, testicular atrophy/testosterone deficiency, and prior radiation to region.

Question 24

In which type of nucleus does position decay occur?

Beta particle emission?

Answer 24

proton rich nucleus (neutron poor)

Beta particle emission happens in neutron rich nuclei

Question 25

Perfusion agent for V/Q scans?

Ventilation choices?

Answer 25

Perfusion: Tc99m MAA

Ventilation:

Either Tc99m DTPA—multiple projections, renal filtration

OR

Xe-133– 1-3 views, washes out, requires a special Xenon trap and is fat-soluble and has high sensitivity for COPD

Question 26

What tracer was used?

Answer 26

Ga^68 DOTATATE

Binds SSTR2 receptors

Question 27

What does Nuclear Regulatory Commission (NRC) regulation 10 CFR Part 35 deal with?

Answer 27

Medical use of by-product radioactive material

10 CFR Part 35 is titled “Medical Use of By-product Material,” and is a key regulation for Nuclear Medicine Authorized Users and physicians performing radiation therapy

Question 28

what med is used to evaluate chronic cholecystitis?

Answer 28

Syncalide

(c terminal octopeptide of cholecystokinin)

GB ejection fraction should beat at least 38%

Question 29

recommendations for breastfeeding and I-131?

Answer 29

Cessation prior to therapy

Issues include:

radiation to the mother’s breast as lactating breasts accumulate more of the I-131. radiation dose to the child due to proximity of the child to the breast during feeding, actual I-131 expressed in breast milk.

For these reasons, the recommendation is to stop breastfeeding several weeks (4-6) prior to radioactive ablation.

Question 30

Is this pattern typical for graves?

Answer 30

No, would be diffusely enlarged and homogenous uptake without nodules (although CAN have superimposed nodules)

Toxic multinodular goiter, toxic adenoma, hashimoto’s toxicosis, endemic goiter can all look like this