Presentation on theme: "Nuclear Medicine Department Loyola University Medical Center"— Presentation transcript:
1 Nuclear Medicine Department Loyola University Medical Center QUALITY CONTROLIN THE HOT LABStephen M. Karesh, Ph.D.Nuclear Medicine DepartmentLoyola University Medical CenterMaywood, IL 60153
2 RATIONALE FOR PERFORMING QUALITY CONTROL For certain procedures, IT'S THE LAW.Non-Diagnostic Study ==> Procedure must be repeated; increased radiation dose and patient discomfort; delayed diagnosis
3 "Would I inject this into my mother?" CRITERIONYou must be able to answer "yes" to the question,"Would I inject this into my mother?"
4 CLASSIFICATION OF IMPURITIES TYPE EXAMPLE EFFECTRadionuclidic Mo Radiation Dose Poor Image QualityRadiochemical HR Tc Poor Image Quality Altered Radiation DoseChemical Al3+ Poor Image Quality
5 DETECTION OF IMPURITIES TYPE OF IMPURITY METHODRadionuclidic Dose Calibrator or Multichannel AnalyzerRadiochemical Thin Layer ChromatographyChemical Colorimetric
6 Required QC Testing of a Mo/Tc Generator TEST FREQUENCY SPECIFICATIONSMo Breakthrough Every Elution <0.15 mCi Mo/mCi Tc at tadministrationAl3+ Breakthrough Every Elution <10 ppm of Al3+; may be expressed as mg/ml
7 OPTIONAL QC TESTING OF A Mo/Tc GENERATOR TEST FREQUENCY SPECIFICATIONSHR Tc Every Elution < 2% (Reasonable limit; presently no legal limit)
8 QC test procedures for mo/Tc generator Mo-99 breakthrough:Mo-99 is assayed directly in the special lead pig supplied by manufacturer of your dose calibrator. Tc-99m is then assayed directly in the plastic sleeve. Activity (mCi) of mo-99 is divided by activity (mCi) of Tc-99m to obtain a ratio.
9 QC Test Procedures for Mo/Tc Generator Mo-99 Breakthrough:If this ratio is <0.15 mCi Mo-99 per mCi of Tc-99m at time of administration, 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.
10 with your dose calibrator with your dose calibrator Mo-99 Breakthrough TestStep 1 Step 2Special Pb pigdesigned for usewith your dose calibratorPlastic sleevedesigned for usewith your dose calibrator
11 QC TEST PROCEDURES FOR Mo/Tc GENERATOR 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 Al3+ Ion Breakthrough Test. Units may be also be expressed as mg/ml.
12 Aluminum Ion Breakthrough Test Special paper saturated with aluminon reagent,sensitive to Al3+ on a ppm basisGeneratorEluate10 ppm Al3+standardIf “generator eluate” spot is less redthan “Al3+ standard” spot, then eluatehas passed the Al3+ ion breakthrough test.
13 Radiochemical Impurities in 99mTc Radiopharmaceuticals Free Tc Chemical form: pertechnetate, TcO4-Hydrolyzed Reduced Tc (Chemical form is probably TcO(OH)2.H2O, a hydrated Tc-oxideFor 99mTc MAG3, possible impurity is 99mTc tartrateFor 99mTc HMPAO, there are stereochemical impurities.
15 Tc-99m CHROMATOGRAPHY: SEPARATION ON STRIP SEPARATION OFSYSTEM RADIOCHEMICAL SPECIESSilica Gel/saline HR Tc in bottom half; all other species in top half.Paper/acetone or Free Tc in top half; all other paper/MEK species in bottom half.
17 Tc-99m CHROMATOGRAPHY:SEPARATION ON STRIPSEPARATION OF SYSTEM RADIOCHEMICAL SPECIESITLC-SA/20% saline HR Tc in bottom half; all other species in top half.ITLC-SG/water Free Tc in top half; all other species in bottom half.
18 EXCEPTION TO THE RULEFor insoluble Tc-99m Radiopharma-ceuticals (e.g., Tc-MAA, Tc-SC), it is only necessary to test for the presence of free Tc. No simple system can effectively separate colloidal HR Tc from an insoluble product, so HR Tc cannot be measured in these products. We therefore ignore its presence.
19 STRIP DESIGN top of strip 6 cm solvent front 5 cm cut line 3 cm origin 1 cmstrip bottom 0 cm
20 Labeling efficiency =100% - % HR Tc - % Free Tc CALCULATIONS% Impurity = CPM IN HALF OF STRIP X 100%CPM IN WHOLE STRIPLabeling efficiency =100% - % HR Tc - % Free Tc
21 Migration Patterns of Tc-MDP Paper/acetone Si gel/salineFree TcTc-MDPHR Tc
22 Migration Patterns of Tc-MDP Paper/acetone Si gel/saline1,00099,00099,0001,000Free TcTc-MDPHR Tc
24 Quality Control Of Dose Calibrators Test Frequency Regulatory AgencyAccuracy Annually NRC/Dept Of Nuclear SafetyConstancy Daily NRC/Dept Of Nuclear SafetyLinearity Quarterly NRC/Dept Of Nuclear SafetyGeometry Tinstallation NRC/Dept Of Nuclear Safety
25 GEOMETRY TEST MUST ALSO BE PERFORMED AFTER REPAIR, RECALIBRATION OR AFTER MOVING INSTRUMENT
26 ACCURACY TESTThis test is designed to show that the calibrator is giving correct readings throughout the entire energy scale that we are likely to encounter. Low, medium, and high energy standards (usually Co-57, Ba-133 or Cs-137, and Co-60, respectively), are measured in the dose calibrator using appropriate settings. Standard and measured values are compared.
27 ACCURACY TEST: Tc-99m Standard Energy expected measured (keV) value (mCi) value (mCi)CoCsCo ,
28 CONSTANCY TESTThis test measures precision and is designed to show that a long-lived source, usually 30 y Cs-137, yields reproducible readings on a daily basis on all isotope settings we are likely to use. The Cs-137 source is placed in the dose calibrator. Activity is then measured on the Cs-137 setting and all other settings used on a daily basis. Values are recorded in the dose calibrator logbook and are compared with recent values to determine if instrument is maintaining constancy on a daily basis.
29 CONSTANCY TEST USING Cs-137 Isotope Reading (mCi)Setting Mon Tues Wed Thu FriCsGaTlTc-99mIIInXe
30 LINEARITY TESTThis test is designed to prove that the dose calibrator readout is linear for sources varying from the mCi range through the mCi range. A high activity Tc-99m source ( mCi) is measured at T0 and at predetermined time intervals up to 48 hours. Expected and actual measurements are compared (and may be analyzed graphically) to determine if the instrument is linear throughout the activity range we are likely to encounter.
31 LINEARITY TEST: Tc-99m Elapsed expected measured time (hr) value value
32 GEOMETRY TESTThis test is designed to show that correct readings can be obtained regardless of the sample size or geometry. One ml of Tc-99m in a 10 ml syringe (activity 25 mCi) is measured in the dose calibrator and the value obtained is recorded. The activity is then diluted with water to 2 ml, 3 ml, 5 ml, and 10 ml. At each of these points a reading is taken and the value recorded. Data are then evaluated to determine the effect of sample geometry on the dose calibrator reading. If instrument is geometry-dependent, it may be necessary to routinely correct readings obtained when using calibrator.
33 GEOMETRY TEST: 10 ml SYRINGE Sample Volume Activity (mCi)
34 Specifications: Dose Calibrator QC Tests 1. Deviation from standard or expected values must be within + 10%.2. If Deviation > 10%, then obligation is to record value, note repair or recalibration of instrument, retest, and record new values.3. In addition to the above steps, every dose must be corrected mathematically until the instrument is repaired. There is NO LONGER a reporting requirement.
35 FULL-WIDTH HALF-MAXIMUM VALUE Determines ability of a sodium iodide (thallium) or solid state crystal to resolve gamma ray energies. Measures only resolution, not sensitivity.for NaI(Tl), Normal Value is 6-10%for Ge(Li) Crystal, typical value is <1% across entire energy spectrum.
36 FULL-WIDTH HALF-MAXIMUM VALUE % FWHM = DE x 100%Epeak
37 What is % Full Width Half Maximum for the Curve Shown Below? E = 662 keVE = 70 keV
38 Full Width Half Maximum Determination E = 662 keV% FWHM = DE x 100%Epeak% FWHM = x 100% = 10.6 %662E = 70 keV