The standardization of 62Cu and experimental determinations of dose calibrator settings for generator-produced 62CuPTSM.
The Positron Emission Tomography agent 62Cu Pyruvaldehyde Bis(N4-methyl)thiosemicarbazone (PTSM) has been standardized by the National Institute of Standards and Technology (NIST) using 4 pi beta liquid scintillation counting with 3H-standard efficiency tracing. Using a measurement model developed at NIST for the determination of experimental dose calibrator dial settings for short-lived radionuclides, the correct dial settings for 62CuPTSM in a clinically useful geometry (a 35 ml plastic syringe containing 33 ml of solution) as well as the standard NIST 5 ml glass ampoule have been elucidated. This measurement model is fully described, as is the treatment of associated uncertainties. The correct instrument settings for the NIST Capintec CRC-12 re-entrant ionization chamber ('dose calibrator') were found to be '499 +/- 6' and '489 +/- 8', respectively, for the syringe and ampoule geometries. The stated uncertainties are expanded (k = 2) uncertainties. The expanded uncertainties in the measured activity arising from these new dial settings are +/- 0.8% and +/- 1.4%, respectively, for the syringe and ampoule. The measured activities using these settings are lower than those obtained from the manufacture's recommended setting of '448' by 9.7% for the syringe and 7.7% for the ampoule, and underscore the need for experimental verification of the dose calibrator settings for each radionuclide and each geometry used in the clinic.
Zimmerman
B E
BE
Physics Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA. bez@nist.gov
Cessna
J T
JT
D002138:Calibration; D003301:Copper Radioisotopes / Q000032:analysis* / Q000592:standards*; D009942:Organometallic Compounds / Q000032:analysis*; D019275:Radiopharmaceuticals / Q000032:analysis*; D012015:Reference Standards; D012588:Scintillation Counting / Q000379:methods / Q000592:standards*; D013882:Thiosemicarbazones / Q000032:analysis*; D014055:Tomography, Emission-Computed / Q000379:methods; D014316:Tritium
D003301:Copper Radioisotopes; D009942:Organometallic Compounds; D019275:Radiopharmaceuticals; D013882:Thiosemicarbazones; D014316:Tritium; C052629:copper pyruvaldehyde bis(N(4)-methylthiosemicarbazone) complex