HomeStretch CRACK Physics NUCS Flashcards
(35 cards)
Isobaric transition means?
Which type of decay?
No change in mass (like a barbell)
beta minus decay and electron capture (mass doesn’t change)
beta minus decay
Situation 1: “Lots of Neutrons, Not enough Protons”
neutron excess (proton deficient)
changes neutron to proton and emits a beta particle - isobaric transition
e- emission can damage DNA - basis of radionucleotide therapy
The only graph thing that goes from right to left
alpha decay
heavy unstable atoms
lots of tissue damage
Beta Positive decay
Situation 2a: “Lots of Protons, Not Enough Neutrons - The Rich Guy”
Proton excess (neutron deficient) [rival of e- capture]
has at least 1.02MeV
positron emission, leading to two 511 keV photons which fly 180 degrees apart
e- capture
Situation 2b: “Lots of Protons, Not Enough Neutrons”
proton excess (neutron deficient) [rival of beta + decay]
Does not require 1.02 MeV
Leads to gamma emission and characteristic radiation
GIT! Gallium, indium and thalliam decay this way. . .
Cyclotron produce radioisotopes
Moly-99
F-18
Ga-67
Tl-201
Reactor produced radioisotopes
Moly-98 (which can then be placed in a cyclotron to make moly-99)
I-131
Xenon-133
Tl-201
Generator produced radionuclides
Tech-99m (from cyclotron produced Moly-99, which was made from reactor produced moly-98)
Krypton-81m (from cyclotron rubidium-81)
The NRC allows what moly99 to tech99m ratio in the ______ purity test
0.15 micro Ci of Mo to 1 milli Ci of Tech-99m in the radionuclide chemical test at the time of administration
(you can remember the units if you think you don’t want to have to much Mo!)
Chemical purity test
Performed with what?
Limit/number?
What do you see in a liver/spleen scan if this is not correct?
How about in other scans?
the chemical = aluminum!
performed with a pH paper
the allowed amount is < 10 microgram of Al / 1 mL
Liver/spleen scan + LUNG = Al contamination
Tc scan + LIVER activtiy = Al contamination
Radiochemical purity test
Limits
radiochemical = free tech99m!
thin-layer chromatography is used to test for this
95% Na99mTcO4
92% for 99mTc Sulfor colloid MAA
91% for all other Tc radiopharmaceuticals
What radioisotopes use collimator:
Low energy
Medium Energy
High energy
Low (1-200keV) = Tech99m, I123, Xe133, TI 201
Medium (200-400keV) = Ga67, In111
High (>400) = I131
Field uniformity recommended counts for both extrinsic and intrinsic range?
5-10 million
QA intervals for Gamma Cameras:
Field uniformity (external and internal) (and limit)
Energy window
Image linearity and spatial resolution
Center of rotation
- Field uniformity (external and internal)
- external (with collimator) = daily
- internal (without collimator) = weekly
- 2-5% non-uniformity is allowed (1% if SPECT!)
- Energy window = DAILY
- Image linearity and spatial resolution = WEEKLY
- Center of rotation = MONTHLY
Maximum dose a GM counter can handle before goes into dead time?
100 mR/h
Ion chambers can be used to detect exposure rates from ___ to ___
0.1 to 100 R/h
Well Counter - What kind of instrument is it?
Sodium Iodine (basically a small gamma camera, with just 1 PMT (good for low dose, can’t tell what types of radiation, good for Wipe test)
(doSe callibrator is a gaS ionization chamber)
Dose calibrator QA
Dose should be with __% of computed activity?
Consistency
Linearity
Accuracy
Geometry
- 5%
- Consistency = DAILY
- Linearity = Quarterly
- Accuracy = at instillation and annually
- Geometry = at installation and when you move the device
NRC Trivia
10 CFR Part 19
10 CFR Part 20
10 CFR Part 35
- 10 CFR Part 19 = notices, instructions, and reports to workers
- 10 CFR Part 20 = standards for protection against radiation
- 10 CFR Part 35 = medical use of by-product material
MAJOR Spills
- Tc-99m & Tl-201 (the lower energy ones) = 100 mCi
- Ga-67, In-111 & I-123 (medium energy ones) = 10 mCi
- I-131 (high energy) = 1 mCi
Regulations affecting the general public
Annual dose limit
No greater than what limit in an “unrestricted area”
“restricted area” = ?
- Annual dose limit = 100 mrem (1mSv)
- No greater than what limit in an “unrestricted area” = 2 mrem/hour
- “restricted area” = any place that receives a dose greater than 2mrem/h
Signs must be placed with the following slogans with what radiation levels:
Radiation area
High radiation area
Very high radiation area
- Radiation area = 0.005 rem (0.05mSv) in 1 hour at 30cm
- High radiation area = 0.1 rem (1mSv) in 1 hour at 30cm
- Very high radiation area = 500 rads (5gray) in 1 hour at 1 meter
1mSv = __ rem = ___ rad = ___ Gy
1mSv = 0.1 rem = 0.1 rad = 0.001 Gy
NRC occupational exposure dose limits
Total body dose per year
Dose to ocular lens per year
Total equivalent organ dose (including skin) per year
Total equivalent extremity dose per year
Total dose to embryo/fetus over entire 9 months
If fetus already got that dose, how much more for the remainder of the pregnancy?
- Total body dose per year = 5 rem (50 mSv)
- Dose to ocular lens per year = 15 rem (150 mSv)
- Total equivalent organ dose (including skin) per year = 50 rem (500 mSv)
- Total equivalent extremity dose per year = 50 rem (500 mSv)
- Total dose to embryo/fetus over entire 9 months = 0.5 rem (5 mSv)
- If fetus already got that dose, how much more for the remainder of the pregnancy? = 0.05 rem (0.5 mSv)
