Physics Flashcards
What type of atom undergoes: Beta minus, beta plus, Electron caputre and alpha decay?
- Beta negative - Neutron rich elements - want to gain a proton so have to get rid of that negative energy
- Electron capture and Beta plus: Proton rich elements - need to get rid of proton
- Electron capture is low energy bitches that just take in an electron and grab its negative power!
- Alpha is large elements.
What is isobaric or isomeric change?
Isobaric - Mass stays the same but the structure of the nucleus changed
Isomeric - energy changed… nothing else
What is an isotope, isotone, isobar and Isomer?
Isotope = protons stayed the same
Isotone = neutrons are the same
Isobar = Mass is the same
Isomer = Energy changed
How does Mo99 turn to Tc99?
First it undergoes beta - and turns into a metastable 99mTc, then it undergoes isomeric gamma release of 140keV and becomes 99Tc.
What can happen in isomeric transition that would be bad for imaging?
Internal Conversion - instead of giving off a gamma ray the energy is transited to an electron that flies off as an auger electron and characteristic electrons.
A nuclear reactor makes what while a cyclotron produces?
Nuclear reactor produces neutrons
Cyclotron produces charged particles
What does Carrier free mean?
Carrier free means no left over parent element… a cyclotron is carrier free.
What are the three types of half life and how do they relate?
Phyiscal, biological and effective
1/Effective = 1/physical + 1/Biological
How long till the radioactive material is considered gone?
10 half lives.
What is the biologic and physical half life of I131?
Biologic = 24 days
Physical = 8 days
What does Ci and Bq measure and how do they relate to eachother?
Becquerel and Ci = number of disintegrations per second
1 Ci = 3.7 x 1010 dis/sec
1 Bq = 1 dis/sec
37 Bq = 1 mCi
What are the parts of a gamma camera?
Collimator
Scintillator - NaI and thallium
Photomultipler
Computer
What collimator is the workhorse of nuke med?
Parallel Hole collimator
What radiopharms use a low energy collimator?
99mTc
I123
X133
Thallium 201
Co57
What radiopharms use a medium energy collimator?
Ga 67
In111
What radiopharms use a high energy collimator?
Fluoine18
I131 (beta emitted as well)
Ga68
What size holes and septa do we use for high energy radiopharms?
Long thick septa
Large holes
What does the pinhole collimators due to the image?
Magnifies and inverts
If the detector:pinhole length is the same as the pinhole:patient length than no magnification
What are the types of collimator holes?
Pinhole
Parallel
Converging - magnifies
Diverging - minifies
What do photomultipler tubes do?
Detect light and turn it into elctric signal which it accelerates
What is downscatter?
It is when you use two different radiopharms with different energies. If you use the higher energy first it may cause masking of the lower energy. So USE THE LOWER ENERGY FIRST.
What are the advantages and disadvantages of a Geiger-Muller counter?
Detects ionizing radiation (particle or not)
Very sensitive
Great for low level surveying
Terribel for very high radiation - gas in the counter becomes ionized and creates a voltage… then the ionization must dissipate before it response again.
Max dose 100 mR/H
What are the advantages and disadvantages of a ion chamber?
Measure dose rates
Used in higher rates
Lower sensitivity
Max dose 100R/h
What are the different types of dosimeters?
- Pocket ionization detector:
- ionization chamber
- real-time estimates - must be charged and zeroed to get this
- Solid state dosimeter:
- Acumulated dose or rate with real time LCD display
- Film Badge:
- Cummulative dose
- Optically stimulated dosimeter:
- Replaced film badge with chip or strips under a filter
- Thermo-luminsecent dosimeter:
- Ring badge
- Worn facing the palm/target
What is a well-counter?
Small gamma camera (NaI) with one PMT
Used in wipe test
What are considered major spills?
100mCi of Tc or Thallium
10mCi of I123, Indium, Ga67
1mCi of I-131
What is the highest mrem/hr for people (general public) in a unrestricted area? What’s the annual dose for the general public?
2mrem/hr
100mrem for general public annual dose
NRC occupational exposure dose limits:
- Total body dose per year
- Dose to ocular lens per year
- Total equivalent organ dose per year
- Total equivalent extremity dose per year
- Total embroy dose over 9 months
- 50mSv - body
- 150mSv - ocular
- 500mSv - Organ
- 500mSv - Extremity
- 5mSv (this is after declaration of pregnancy) - fetus
How does rads relate to rem?
How do rad relate to Gray?
How does mSv relate to mrem?
What are the first three decimal places called?
1 rad = 1 rem
1 rad = 0.01 Gy
1mSv = 100mrem = 0.1 rem
Deci (0.1), centi (0.01), milli (0.001)
What is radionuclide purity in regards to Tc and how is it done?
Making sure it is Tc and not Mo.
Put it behind lead and see if you get a signal. Mo will break through with 740keV while Tc at 140keV will not.
What is chemical purity in regards to Tc and how is it done?
Testing for Al by pH
Al will cause uptake of Tc in the liver and lungs
So on a Tc scan it will light up the liver, and on a liver scan with MAA it will light up the lungs
What is radiochemical purity in regards to Tc and how is it done?
Testing for free Tc
Use a chromatography
Where is uptake of free Tc?
Gastric
Salivary gland
Thyroid
Sweat glands
Choroid plexus
What causes free Tc to be present?
Air in vial causing oxidation
What is transient equilibrium and where is it seen?
Seen in Mo and Tc generators
The daughter (Tc) has a shorter half life and therefore equilbrium between birth and death of Tc happens at 4 half lives.
