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23 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What physical qualities assure quality of RP?
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Color and clarity are important characteristics of RP’s. Most RP’s are clear and a quick check of their appearance in the vial or syringe should be done prior to drawing the dose or administering the dose. Another visual check is particle assessment of MAA, sulfur colloid, colloidal albumin and other particulate RP’s. This requires a microscope and a hemocytometer.
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Chemically how do you know you have a neutral solution?
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For neutral solutions, the H3O+ and OH- are equal. A higher H3O+ conc. Indicates the solution is acidic, a higher OH- conc. Indicates the solution is basic. The conc. Can be expressed as the molarity (moles/liter) of ions in solution.
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What is pH?
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The concentration has been simplified through the use of pH, which is the power of hydrogen.
Specifically, pH is the negative log of the hydrogen ion concentration, a number between 0 and 14. What indicates basic or acidic solutions? |
Solutions with a pH larger than 7 are basic, a pH below 7 is acidic.
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What is the numerical difference between pH 6 and pH7?
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10
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What is the ideal pH for any pharmaceutical?
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THE IDEAL RADIOPHARMACEUTICAL WILL HAVE A pH OF 7.4 AS THIS IS THE pH FOR BLOOD.
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What is ionic strength and what is isotonic?
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Radiopharmaceuticals are normally isotonic, meaning they have approximately the same amount of dissolved salts, and electrolytes.
What does this mean on the cellular level? |
The solute concentration and the free water concentration are the same inside and outside the cell, water flows in and out of the cell at an equal rate
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What are the 3 Measures of Purity for Radiopharmaceuticals?
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Radionuclidic Purity
Radiochemical Purity Chemical Purity |
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What is Radionuclide Purity?
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The fraction of the radioactivity present that is in the desired form is the radionuclidic purity. Radionuclidic impurities can add to patient dose, and degrade the image by causing uptake in non-target tissues and or increase background.
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Radionuclidic impurites can be identified by a gamma spectroscope or scintillation counter. How do you identify impurites with similar energies as the desired isotope?
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by identifying half life
What is the most probable contaminant for Tc-99m? |
Mo-99, allowable level is .15 microcuries per millicurie of Tc
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What is it called when the accepted level of Mo-99 of .15microcuries per 1 millicurie of Tc-99 is exceeded since the half life of Mo-99 is longer?
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Mo breakthrough
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What impurity would you expect to find in I-123 capsules?
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I-127, 125, 124
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What is radiochemical impurity and why is it important to imaging?
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The action of radiochemical impurities is similar to that of radionuclidic impurities, they degrade the image and add to patient dose. The fraction of the total activity in the desired form is the radiochemical purity
What causes decomposition of RP? |
-light
- action of the solvent - change in temperature - change in pH - oxidation/reduction - radiolysis |
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What is the importance of chemical purity?
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Non-radioactive substances in the preparation of the RP when contaminated will cause interference with the labeling process
What is the most common one with Tc-99m? |
Aluminum contamination, any presence of Al is called aluminum breakthrough
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What is the problem with aluminum breakthrough?
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It can cause colloidal Tc99m, like SC will cause uptake in lungs, liver and spleen
How do you test for the presence of Al and what is the allowable level of contamination? |
Colorimetric methods, drop of eluate is placed on test strip, compared with standard, if darker than standard then Al concentration is too high.
10 micrograms/ml is allowable limit |
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What is another impurity that appears in reduced complexes of Tc?
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tin or the stannous ion
this can cause formatin of tin colloids and or unwanted labeling of RBC's |
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What is used to help stabilize the chemical purity of RP?
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additives of sodium ascorbate, ascorbic acid, sodium sulfite
as well as keeping it refrigerated and in the dark |
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What is chromatography?
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placing a small drop of RP on ITLC (Instant Thin Layer Chromotography) strip and allowed to dry. Then the strip is placed in solvent, allowed to develop, cut into sections and counted with a well counter
What solvents are used? |
Water, saline, acetone, methanol, methel ethyl ketone (MEK)
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What is the primary reason for chromatography?
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To verify the radiochemical purity of the RP
What is the accepted level of purity? |
90%
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What is the goal for processing Tc99m or any RP?
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To reduce it to the proper level and to get it to bind to the labeling agent like MDP, etc
When it doesn't bind what is it called? |
Free Technetium or if it reduces and doesn't bind it is hydrolyzed free tech
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What is detected by ITLC?
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Free TcO4-
99mTc Tin Colloid 99mTcO2 (technetium dioxide) |
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How are the chemical impurities measured with chromatography?
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by measuring the chemical components as they travel up the paper called the Rf # by this equation:
Rf= d of center of spot from the origin/d of solvent front from origin what is the result if components migrate with solvent? remain at origin? |
If Rf = 1.0 the components migrate with the solvent If Rf = 0 the component remains at the origin.
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What are the methods of sterilizing RP?
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autoclaving (pressurized steam)
membrane filtration |
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What is apyrogenicity?
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products of the metabolism of bacteria and other microorganisms that can cause fever. Sterilization can't rid of this but the bacteria that causes it
what is the test for this? |
injecting rabbits or LAL test (opaque gel forms if pyrogens are present)
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