two or more nuclides of the same element. EX: I-131, I-123
nuclides that have the same number of neutron, but different numbers of protons.
have the same mass number, but different numbers of protons and neutrons.
- 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
the stability of a nucleus is related to two factors:
- the ratio of protons to neutrons in the nucleus.
- the nuclear binding energy
a neutron rich radionuclide tends to decay by
beta emission to decreases the number of neutrons in the nucleus
a proton rich radionuclide tends to decay
by positron emission or electron capture
what is carrier state
radioactive products of a reactor or cyclotron may contain stable isotopes
what is specific activity?
how radioactive based on weight.
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.
relationship exists when the half life of the parent is not more than about 10 to 50x greater than the daughter.
factors affecting tc-99m yield in an elution.
- reduced oxidation state
- mechanical problems
what is channeling>?
caused by an air pocket in the alumina, causing some tc-99m to remain on the column.
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.
limit of mo-99?
.15uCi Mo99/ mCi Tc-99m
when must a generator be tested for Mo-99 breakthrough?
first elution of a new generator.
other radionuclidic impurities include
3 tests performed on tc99m eluate
- measure total activity in Dose calib
- assay radionuclidic purity (Mo99 breakthrough)
- assay chemical purity (Al+3 breakthrough)
breakthrough limits for Sr-82 and Sr-85??
Sr-82= .02uCi Sr-82 / mCi Rb 82
Sr-85= .2uCi Sr-85 / mCi Rb 82
what is the chemical impurity tested for in a Rb-82 generator, and what are its limits?
3 steps for Q/C of RB-82 generator
- column wash
- breakthrough test
- calibration of system check
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.
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.
The reducing agent used in most kits is ?
a stannous (tin) compound, usually stannous chloride
what are the only Tc-99m labeled agents that incorporate Tc in its nonreactive state?
- Tc-99m Sulfur colloid
- Tc-99m Sodium pertechnetate
recommended number of MAA particles?
200k to 700k
parameters used to monitor biological purity
- membrane filtering
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
How to preserve sterility of Radiopharmecutical?
- Use proper aseptic technique
- work in clean enviroment
- good personal hygiene
- use flow hood
What is a pyrogen?
any substance that induces a fever. pyrogens are not destroyed by sterilization.
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.
the extent quality or degree of being posionous.
tested on animals.