Physics Ch 9 Nuc Med Flashcards
neutrons > protons –> what kind of decay?
beta minus
protons > neutrons –> what kind of decay?
beta plus
what happen in beta minus decay?
- beta particle eject
- anti-neutrino eject
- neutron change to proton
beta minus decay –> involve kind of transition? –> isobar/isotope/isotone?
isobaric –> same mass
beta minus decay –> should use what kind of shield –> lead/plastic?
plastic
what happen in beta plus decay?
- positron eject
- neutrino eject
- proton change to neutron
what happen after positron emission?
- travel very short distance
- annihilate w electron
- two 511 keV photons –> 180 deg apart
what happen in electron capture?
- K shell electron –> into nucleus
- proton change to neutron
- release gamma photon
electron capture –> involve kind of transition? –> isobar/isotope/isotone/isomer?
1) isobaric –> same mass
2) isomeric –> release gamma photon
good for imaging?
- beta minus decay
- beta plus decay
- electron capture
- beta minus decay: no
- beta plus decay: Y –> positron
- electron capture: Y –> gamma
Tc-99m –> release what kind of photon? keV?
gamma –> 140 keV
cyclotron –> radioisotopes? (4)
- molybdenum-99
- fluorine-18
- gallium-67
- thallium-201
nuclear reactor –> radioisotopes? (4)
- molybdenum-98
- iodine-131
- xenon-133
- thallium-201
nuclear reactor –> radioisotope production –> cons? (2)
- low yield of desired radioisotope
- produce undesired things
radionuclide generator –> radioisotopes? (2)
- Tc-99m
- krypton-81m
radionuclide generator –> molybdenum-99 –> Tc-99 –> what must be done before can use Tc?
Tc in + state –> stannous ions –> reduce Tc to useable state
Tc-99 –> radionuclide purity test –> what is break-thru?
Mo that is in sample
NRC: Tc-99 –> how much breakthru is allowed?
time of admin –> 0.15 microCi Mo per 1 milliCi Tc
Tc-99 –> chemical purity test –> test for what?
Aluminum contamination
Tc-99 –> Aluminum contamination –> allowable amt?
<10 microgram Al per 1 mL
Tc-99 –> Aluminum contamination –> how test for it?
pH paper
Tc-99 –> Aluminum contamination –> manifestation on imaging? (2)
- Tc scan –> liver activity
- sulfur colloid scan –> lung activity
Tc-99 –> radionuclide purity test –> which assay 1st? –> Mo vs Tc
Mo
presence of free Tc –> MOA? (2)
- lack of stannous ions
- accidental air inject into syringe/vial
presence of free Tc –> imaging finding?
uptake in:
- gastric
- salivary gland
- thyroid
Tc-99 –> radiochemical purity test –> test for what?
free Tc
Tc-99 –> radiochemical purity test –> how test for it?
thin layer chromatography
Tc-99 –> radionuclide purity test –> how test for it?
dose calibrator w lead shield
what is equilibrium?
concentration of parent isotope = conc daughter isotope
[Mo-99] = [Tc-99]
what is transient equilibrium? how many half lives to reach equilibrium? example?
parent isotope half life > daughter half life
4 half lives –> equilibrium for short time
Mo-99 –> Tc-99
what is secular equilibrium?
parent isotope half life»_space;> daughter half life
parent & daugther reach equilibrium –> in equilibrium for long time
what is half life?
- physical
- biological
- effective
- physical: activity –> dec by 1/2
- biological: eliminate (pee/poo) 1/2 substance
- effective: considering both physical + biological half life
effective half life –> formula?
1/effective = 1/physical + 1/biologic
radioactive activity –> unit?
- curie (Ci)
- SI unit –> Becquerel (Bq) = 1 disintegration per sec
nuc med –> what is specific activity?
activity per unit mass (Bq/g)
how specific activity relate to half life?
longer half life –> lower specific activity
how does collimator sensitivity affect resolution?
inc collimator sensitivity –> inc counts to be imaged –> dec resolution
how does distance affect collimator sensitivity?
no effect
collimator –> how does septal length (collimator depth) affect sensitivity? spatial resolution?
- shorter septa: inc sens –> dec resolution
- longer septa: dec sens –> inc resolution
collimator –> how does hole diameter affect sensitivity? spatial resolution?
- small hole: dec sens –> inc resolution
- bigger hole: inc sens –> dec resolution
collimator: low vs high energy tracer –> should use short/long septa length? small/big hole?
low energy:
- short septa
- small hole
high energy:
- long septa
- big hole
collimator –> 4 types?
- parallel
- pinhole
- converging
- diverging
pinhole collimator –> used to image what organ?
- thyroid
- other small parts
pinhole collimator –> image charact:
- not/magnify?
- not/invert?
- mag
- invert
converging collimator (cone beam) –> image charact:
- not/magnify?
- not/invert?
- mag
- not invert
scintillation crystal –> thin vs thick –> how affect..
- sens
- spatial resolution
thin xl:
- worse sens
- better resolution
thick:
- better sens
- worse resolution
V/Q scan –> which image first? –> Xe vs Tc? why?
lower energy photon 1st: Xe –> Tc
if Tc first –> downscatter –> Xe –> can’t accurately pick up Xe peak