Physics - Nucs Flashcards
Mass number: A means what?
sum of protons (Z) and neutrons (N) within nucleus
If A is the same what’s that called?
Isobars
If Z is the same what is that called?
Z = Protons , Isotope
Transmutation is what?
Decay involving the change in the number of protons
What state is the most stable?
Ground State
Isomeric states are
Higher / excited states which are unstable
Excited states transform back to lower-energy states by what?
Gamma-radiation
Gamma rays are what?
Electromagnetic radiation from a nuclear process
What is the change between in the parent and daughter of A and Z after an isomeric transition
They are the same Mass number (A) and Atomic number (Z) is unchanged between parent and daughter
Isomeric states with long lifetimes are called?
Metastable
What happens to A/Z/N from a parent to daughter for the following transition?
Isomeric
No change to A (Mass number) Z (Atomic Number) N (Neutron number)
What happens to A/Z/N from a parent to daughter for the following transition?
Beta Minus
A (Mass number) Z (Atomic Number) N (Neutron number)
A = no change
Z + 1
N - 1
Nucleus emits electrons
What happens to A/Z/N from a parent to daughter for the following transition?
Beta plus
A (Mass number) Z (Atomic Number) N (Neutron number)
A = no change
Z - 1
N + 1
Nucleus emits positrons
What happens to A/Z/N from a parent to daughter for the following transition?
Electron Capture
A (Mass number) Z (Atomic Number) N (Neutron number)
A = no change
Z - 1
N + 1
Atoms emit characteristic x-rays
What happens to A/Z/N from a parent to daughter for the following transition?
Alpha decay
A (Mass number) Z (Atomic Number) N (Neutron number)
A - 4
Z - 2
N - 2
heavy nuclei (Z>82)
What nucs isotopes decay via electron capture?
67-Ga
111 - In
123 - I
What is activity?
transformations per unit time
What is the SI unit of activity
Becquerel = 1 nuclear transformation / second
Non-SI unit of activity
Millicuries 9MCi) 1 mCi = 37 MBq
How is activity related to the decay constant?
Directly proportional
What is the relationship between the decay constant (lambda) and the halflife?
T(1/2) = 0.69/(lambda)
What is effective half-life as related too Physical and biologic half-life
1/effective = 1/phsical decay + 1/biologic
What are the isotopes created by cyclotron?
Ga-67, I-123, F-18, In-111
What isotopes can be made from fission products?
I-131, Xe-133, Sr-90 Mo-99
How do fission products decay
beta minus
Ga-67
Half life
Photons
Production
Decay
78 hours
90,190,290,390
Cyclotron
EC
Tc-99m
Photons
Production
Decay
Half Life
140
Generator
IT - Isomeric transition
6 hours
IN - 111
Photons
Production
Decay
Half life
173, 247
Cyclotron
EC
68 hours
123 I
Photons
Projection
Decay
Half life
159
Cyclotron
EC
13 hours
131 I
Photons
Production
Decay
Half - Life
364
Fission product
Beta
8 days
What is specific activity?
Activity per unit mass (Bq/g)
How is Tc-99m obtained
Moly Mo99 generator
How is Rb82 obtained? Half life?
Sr-82 generator. 1.25 minutes
Starting with a fresh generator how long before equlibrium is reached between parent and daughter?
About 4 half-lives of the daughter
Half life of Mo99. How long is the generator useful?
66 hours (HL), and about 5 working days.
What is transient equilibrium?
What is secular equilibrium?
How long until they are reached?
When the parent is short lived
When the parent is long lived
~ 4 (HL)
In nucs what is an example of: Active transport?
Thyroid Update I 123
In nucs what is an example of: Capillary blockade
MAA for lung perfusion
In nucs what is an example of: Compartmental localization?
Tc99m red cells for blood pool scanning
In nucs what is an example of: Compartmental leakage
Tc99 RBC GI bleed study
In nucs what is an example of: Diffusion
DTPA renal scan
In nucs what is an example of: Phagocytosis
Tc99m sulfur colloid for liver/spleen function
In nucs what is an example of: Physiochemical adsoprtion
Tc99 pyrophosphates for bone scan
In nucs what is an example of: Cell sequestration
111In leukocytes for spleen scan
In nucs what is an example of: Metabolism?
FDG pet
In nucs what is an example of: Neuroreceptor imaing?
F18-florbetaben
In nucs what is an example of: Antibiody reactions
TC-99m monoclonal antibiodies
What is the regulatory limit for moly breakthrough?
5.5 kBq moly per 37 MBq of Tc99m
How do you test for alumina breakthrough?
color paper
How do you check for radionuclide purity
Photopeak in spectroscopy (Mo in Tc)
How do you test for radiochemical purity?
Thin-layer chromatography (Free pertechnetate in 99mTc-DTPA)
What is chemical purity?
Amount of unwated chemical contaminants in the agent
What testing should be performed on radionuclides prior to administration to patients?
Sterility and pyrogen testing
What is the rate of adverse reactions in radiopharmaceuticals?
2 per 100,000
What is the photopeak for 123 - I?
160
What is the photopeak for Tc99m?
140
What is decetion efficiency as it relates to NaI?
% of incident gamma rays totally absorbed in the scintillator via photoelectric effect
How does increasing photon energy effect detection effiency?
decreases it.
How is photoelectric effect and energy related?
PE = 1/E^3
FWHM of Tc99M in a 10 mm NaI crystal is 14 KeV what is the energy resolution?
10% (140 KeV energy for Tc)
The PHA window is likely set to what?
Twice energy resolution
What is a well counter? What is is good for?
Sample is inserted into a well within the crystal.
Identify radionuclides from photopeak energy
Can also measure activity
What is an uptake probe used for?
Quantify radioiodine in patients
Iodine update is measured at once distance and what time after administration?
30 cm and 24 hours after administration.
What is a dose calibrator?
An ionization chamber, meausing dose in MBq or mCi
Administered dose must be within what of the perscrived dose?
20%
Dose calibrator response is checked how often and with what?
Daily, 137 Cs. Measurements should be within 5%
Accuracy of dose calibrators is checked when?
Installation and annually
Linearity of dose calibrators is checked when? How?
Quaterly.
Decay of Tc99m over 72 hours or with lead cylinders to attenuate the signal.
How is location of interaction determined in a PMT system?
Pulse arithemitc circuit board
How do parallel hole collimators change the image size? How does it change with distence? What about resolution as a function of distance?
They don’t. FOV stays the same with distance.
Resolution drops dramaticlly with distance.
How do converging columnators affect image size?
They magnifiy it
How do diverging columnators affect image size?
They minify it
How do pin-hole collimators affect image size?
magnified and inverted
What are useful to use with a low-energy collimator? (Isotope wise)
99m-Tc and 123 I
What isotopes are good to use with a medium-energy collimator?
67 Ga and 111 In
In plannar imaging what is system reolution dominated by?
Collimator resolution
How is collimator sensitivity related to distance?
independent of distance.
How many counts are in a typical scintillation images?
500,000
What is the usual matrix size for nuclear medicine scintillation images?
64^2 or 128 ^2
What is the count/pixel roughtly in NM images?
100
Number of 140 Kev photons absorbed by a 10mm NaI crystal? (percent)
90%
Gamma camera energy resolution is changed how often?
Annually. Measured by FWHM
