Nucs Flashcards
Isobaric transition
No change in mass (beta +, beta -, EC)
Isometric transition
Nrg release (gamma)
Cyclotron isotopes
Produced by bombarding charged particles: 99Mo, 18F, 67Ga, 201Th
Nuclear reactor isotopes
Produced by neutron: 98 Mo (makes 99Mo), 131I, 133Xe, 201Th
Generator
Produced by decay/elution. 99Mo -> 99mTc
Radionuclide purity 99mTc
Breakthrough Mo. < 0.15uCi Mo / 1 mCi Tc. Measured with shields
Chemical purity 99mTc
Free Al -> liver, spleen, LUNG uptake.
< 10ug Al per mL
Radiochemical purity 99mTc
Free Tc -> stomach, salivary glands, thyroid uptake
> 95% Na99mTcO4
> 92% 99mTcMAA
> 91% all other 99mTc radiotracers
-assessed by liquid chromotography
Types of collimators
1) Parallel (workhorse) IIIIII
2) Pinhole (thyroid) - mags and inverts
3) Converging - mags //II
4) Diverging - minimizes \II//
Downscatter
Use lower nrg isotope first if pt needs multiple isotopes
- Compton scatter from higher nrg isotop obscures lower nrg peaks
Star artifact
septal penetration from hexagonal collimator
Field Uniformity Test (SPECT)
Flood test. Daily w/ collimator
Nrg Window Test (SPECT)
Daily
Image linearity and spatial resolution test (SPECT)
Weekly
Geiger Counter/Ion chamber calibration test
Yearly
Center of rotation (SPECT)
Monthly
Consistency test (Ionization chamber)
Daily
Linearity test (ionization chamber)
Quarterly
Accuracy (Ionization chamber)
During installation, annually
Geometry test (Ionization chamber)
During installation, when moved
Major Spills
> 100 mCi Tc, Th
10 mCi In, 123I, 67Ga
1 mCi 131I
Clear area, cover spill, notify Rad safety
Dose limit - general public
< 2 mrem/hr
Occupational limit body
5 mrem (50 mSv) / yr
Occupational limit lens
15 mrem (150 mSv)
Occupational limit single organ (ie: skin)
50 mrem (500 mSv)
Occupational limit extremity
50 mrem (500 mSv)
Occupational limit embryo
0.5 mrem (5 mSv)
Limit hot sink
1 Ci
Dose limit 131I to general public
5 mSv
Reportable event
> 5 rem or > 50 rem single organ
Call NRC 24 hrs
Write letter 15 days
Notify doctor 24 hrs
White 1 Receiving Isotopes
< 0.5mRem/hr @ surface
0 mRem/hr @ 1m
Yellow 2 Receiving Isotopes
< 50 mRem/hr @ 1m, > 0.5
Yellow 3 Receiving Isotopes
< 200 mRem/hr @ 1 m, > 50
Yellow 2 Transporting Isotopes
< 1 mRem/hr
Yellow 3 Transporting Isotopes
> 1 mRem/hr, < 10 mRem/hr
Uniformity test (PET)
Blank scan. Daily
Normalization scan (PET)
Monthly
99mTc
140 keV, 6hr
201Tl
69-83 keV, 3 days
133Xe
81 keV, 5.2 days
123I
159 keV, 13 hr
131I
364 keV, 8.1 days
67Ga
93, 184, 296, (388) keV, 78 hr
111In
171, 245 keV, 2.8 days
BioD 123I-MIBG
Liver > spleen
Peds patient
Salivary glands
Myocardial activity
BioD 111In Octreoscan
Spleen > liver
Salivary glands
No myocardial activity
BioD 99Tc-Sestamibi
Thyroid
Heart
Liver
BioD 18F-FACBC (Axumin)
Intense pancreas
No brain
BioD 67 Ga
Lacrimal glands
BioD DOTATATE
Intense Pituitary
No brain
Intense spleen
Low NRG collimator
< 150 keV (Tc)
Medium NRG collimator
< 300 keV. NOT Tc, NOT 131I
High NRG collimator
> 300 keV. 131I only
Written Directive
- Name
- Radioisotope (Therapy)
- Dosage
- Route
*Required for 131I > 30 uCi, or any therapy
Stochastic model
(Random), no threshold. Increase radiation dose increases chance
Deterministic model
Threshold dose -> effect
Most sensitive phase of cell cycle
M phase.
Followed by G2. S least sensitive.
Acute radiation syndrome (ARS)
NVD, Feel OK, Possible death
Faster symptoms appear, worse outcome.
> 2 Gy
Fetal radiation effects
Implantation -> can result in fetal loss if > 100 mGy. No lasting effects.
8-15 wks - sensitive time. Mental retardation/decreased head diameter
> 15 wks - less sensitive
Fetal IQ drops 30 pts for every sv. 40% risk of retardation at 1 sv.
Skin erythema
2 Gy
Telangiectasia
10 Gy, 52 wks
Desquamation
13-18 Gy
Ulceration
18-24 Gy
Temporary Epilation
3 Gy
Permanent Epilation
7 Gy
Radiation-induced cataracts
Posterior lens
Male temporary sterility
0.15 - 2.5 Gy
Male permanent sterility
5 Gy
Female sterility
2-10 Gy (higher in young females)
Background radiation
~3 mSv/yr
Fetal death
100 mGy in first 2 weeks
Most radiosensitive organ
Breast > gonads
Shielding
Gamma rays - high Z material (lead, concrete)