Generator Quality Control
TYPES OF IMPURITIES IN A Mo-99/Tc-99m GENERATOR
Radionuclidic impurity is Mo-99; results in Increased Radiation Dose, poor image quality
Radiochemical HRTc-reults in Poor Image Quality; Increased Radiation Dose
Chemical impurity- Al3+ results in Poor Image Quality due to labeling problems
REQUIRED QC TESTING OF A Mo/Tc GENERATOR
Mo Breakthrough, Every Elution- specification: <0.15 µCi Mo/mCi Tc at time of injection
Al3+ Ion Breakthrough, Every Elution- specification: <10 ppm of Al3+; may be expressed as µg/ml
OPTIONAL QC TESTING OF A Mo/Tc GENERATOR
Hydrolyzed Reduced Tc- Every Elution, specification: < 2% (Reasonable Limit, presently no legal limit)
QC TEST PROCEDURES FOR Mo/Tc GENERATOR
1. Mo-99 Breakthrough: Mo-99 is assayed directly in the special lead pig supplied by the manufacturer of your dose calibrator. Tc-99m is then assayed directly in the plastic sleeve in your dose calibrator. Activity (uCi) of Mo-99is divided by activity (mCi) of Tc-99m to obtain a ratio. If this ratio is <0.15 µCi Mo-99 per mCi of Tc-99m at time of injection, the generator eluate has passed the Mo-99 Breakthrough Test. As a rule of thumb, if the ratio is <0.038 at time of elution, the material will be suitable for injection for at least 12 hours.
2. Aluminum Ion Breakthrough: Al3+ ion is measured colorimetrically. A drop of the eluate is placed on one end of a special test paper; a drop of a standard solution of Al3+, concentration 10 ppm, is placed on the other end of the test strip. If the color at the center of the drop of eluate is less red than that of the standard solution, the eluate has passed the Aluminum Ion Breakthrough Test. Units may be expressed as ug/ml.
|Stephen Karesh, PhD.||
Last Updated: August 14, 1996