Nucs Flashcards
Mo-99 is the mother isotope for elution of Tc-99m
what is used to test for breakthrough in the eluate?
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
what effect does glucagon have on peristalsis and vasodilation?
decreases peristalsis and increases vasodilation
What is the T1/2 of Rb 82, what is it used for
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.
History of thyroid cancer, elevated thyroglobulin and negative I131 whole body survey. What exam can you do?
PET can be used to look for mets
what is the critical organ in a hepatobiliary scan?
gallbladder wall
If you double your matrix size by how much does your # of pixels increase?
4x
Remember that the smaller the pixel the less counts per pixel which increase STN
What type of scan?
Octreoscan
avid lesion in the pancreas
most likely islet cell tumor like gastrinoma or insulinoma
could also be carcinoid (more rare)
21M without trauma
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
dipyramidole mechanism of action?
Indirect vasodilator for coronary arteries
acts via preventing reuptake and deamination of adenosine—> increases tissue levels of adenosine
Which drug limits release of pertechnetate by gastric mucosal cells and thus enhances sensitivity for meckel’s scan?
cimetidine (H2 blockers)
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
what drug causes dose related increase in heart rate, blood pressure, and myocardial contractility?
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.
what med changes might you make before a 131I- NaI (sodium iodide) scan after ablation/treatment for thyroid cancer?
either decrease dose of levothyroxine (to increase endogenous TSH) or give thyrotropin alpha
What is the half life of Xe133?
Photon Energy?
5.3 days
gamma energy: 81 keV
What measures the biological damage caused by ionizing gamma radiation exposure?
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.
Half life of Thallous Chloride?
TI-201
73 hours
Dose calibrator has what checked on installation or anytime it is moved?
Geometry
Geometry assesses the effect of sample volume &/or configuration in a vial or syringe on the measurement of a sample’s activity.
What are the advantages of In III WBC vs Tc99m HMPAO for infection/inflammation?
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)
Half life of Sodium Fluoride F18
109 minutes
Same as F18 used for PET (with FDG label)*
Mechanism of action Tc99m Tetrofosmin
Passive diffusion
amount delivered to myocytes is 2/2 perfusion
What radiotracer used to evaluate renal cortex?
Tc99m DMSA
Renal cortical imaging—differentiates scar from pyelonephritis
DMSA works by tubular (cortical) binding
Half life of I131 NaI
I123?
I 131 = 8 days, 364 keV
I123 = 13 hours, 159 keV
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.
In which type of nucleus does position decay occur?
Beta particle emission?
proton rich nucleus (neutron poor)
Beta particle emission happens in neutron rich nuclei
Perfusion agent for V/Q scans?
Ventilation choices?
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
What tracer was used?
Ga^68 DOTATATE
Binds SSTR2 receptors
What does Nuclear Regulatory Commission (NRC) regulation 10 CFR Part 35 deal with?
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
what med is used to evaluate chronic cholecystitis?
Syncalide
(c terminal octopeptide of cholecystokinin)
GB ejection fraction should beat at least 38%
recommendations for breastfeeding and I-131?
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.
Is this pattern typical for graves?
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
