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isotope
two or more nuclides of the same element. EX: I-131, I-123
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isotones
nuclides that have the same number of neutron, but different numbers of protons.
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isobars
have the same mass number, but different numbers of protons and neutrons.
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isomers
- nuclides that have the same number of neutrons and protons but have different amounts of energy in their nuclei. ex.
- tc-99 and tc-99m
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the stability of a nucleus is related to two factors:
- the ratio of protons to neutrons in the nucleus.
- the nuclear binding energy
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a neutron rich radionuclide tends to decay by
beta emission to decreases the number of neutrons in the nucleus
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a proton rich radionuclide tends to decay
by positron emission or electron capture
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what is carrier state
radioactive products of a reactor or cyclotron may contain stable isotopes
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what is specific activity?
how radioactive based on weight.
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what is secular equilibrium?
relationship that exists when the half life of the parent is many times greater usually 100x or more than the daughter.
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transient equilibrium?
relationship exists when the half life of the parent is not more than about 10 to 50x greater than the daughter.
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factors affecting tc-99m yield in an elution.
- channeling
- reduced oxidation state
- mechanical problems
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what is channeling>?
caused by an air pocket in the alumina, causing some tc-99m to remain on the column.
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oxidation state?
tc-99m on the column should be in the +7 oxidation state. tc-99m in the reduced state can become bound to the column and not removed by elution.
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limit of mo-99?
.15uCi Mo99/ mCi Tc-99m
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when must a generator be tested for Mo-99 breakthrough?
first elution of a new generator.
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other radionuclidic impurities include
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3 tests performed on tc99m eluate
- measure total activity in Dose calib
- assay radionuclidic purity (Mo99 breakthrough)
- assay chemical purity (Al+3 breakthrough)
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breakthrough limits for Sr-82 and Sr-85??
Sr-82= .02uCi Sr-82 / mCi Rb 82
Sr-85= .2uCi Sr-85 / mCi Rb 82
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what is the chemical impurity tested for in a Rb-82 generator, and what are its limits?
Tin, 1ug/mL
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3 steps for Q/C of RB-82 generator
- column wash
- breakthrough test
- calibration of system check
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kits contain 3 main ingredients
- the compound(chelate) to be labeled with Tc
- a chemical reducing agent
- additives to maintain the quality of the the prepared radiopharm.
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what is the reducing agent in kits for?
it makes the Tc-99m from the generator chemically active so that it will combine with tthe chelate to form the radiopharmecutical.
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The reducing agent used in most kits is ?
a stannous (tin) compound, usually stannous chloride
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what are the only Tc-99m labeled agents that incorporate Tc in its nonreactive state?
- Tc-99m Sulfur colloid
- Tc-99m Sodium pertechnetate
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recommended number of MAA particles?
200k to 700k
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parameters used to monitor biological purity
- sterility
- pyrogenicity
- toxicity
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sterilization methods
- Autoclaving
- membrane filtering
- irradiation
- chemical
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how is sterility testing done?
- done after the fact b/c of short T 1/2
- growth media is inoculated with radiopharmaceutical sample.
- take 5-14 days
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How to preserve sterility of Radiopharmecutical?
- Use proper aseptic technique
- work in clean enviroment
- good personal hygiene
- use flow hood
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What is a pyrogen?
any substance that induces a fever. pyrogens are not destroyed by sterilization.
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Two ways to test for Pyrogenicity
- LAL test ,limulus amoebocyte lysate, uses horsecrab blood, if sample turns LAL gel opaque pyrogens are present.
- RPT test, rabbit pyrogen test, inject sample into rabbit, and monitor temp.
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Toxicity
the extent quality or degree of being posionous.
tested on animals.
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