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A. M. Zimmer*, P. C. Cutrera, M. L. Schaffner,
G. Glesinger, S. M. Spies; Department of Nuclear Medicine, Northwestern
Memorial Hospital, Chicago, IL; Northern Shared Medical Services,
Madison, WI. (651462)
Monday, June 21, 2004, 9:12 AM, Scientific Paper
Session: Radiopharmaceutical Chemistry Track - PET Radiopharmacy
(8:00 AM-9:30 AM) 104 A/B
Objectives: F-18
dose calibration settings for major dose calibrator manufacturers
vary and can result in activity differences in measured F-18 Fluorodeoxyglucose
(FDG) doses. In order to minimize differences in measured F-18 FDG
doses, we report on a method to standardize F-18 calibration settings
using a National Institute of Standards and Technology (NIST) traceable
positron-emitting standard.
Methods: Specific
dose calibrators used included a Capintec CRC-15 (Capintec Inc.)
and a Biodex Atomlab 100 (Biodex Medical). A NIST traceable 1.73
mCi Ge-68/Ga-68 standard (Isotope Products) was obtained from Northern
Shared Medical Services. The traceable standard was calibrated on
the specific manufacturer’s dial setting for Ge-68/Ga-68.
From photon response curves and photon energies and yields, a F-18/Ge-68
ratio was calculated. In addition, the ratio was also experimentally
determined for the calibrators utilized.
Results: A F-18/Ge-68
calibration ratio of 0.95 was calculated and the same ratio was
also experimentally determined for both dose calibrator manufacturers.
With the 1.73 mCi Ge-68/Ga-68 standard, dose calibrator response
readings in a Capintec CRC-15 and a Biodex Atomlab 100 were 1.82
mCi and 1.70 mCi, respectively. Using a F-18/Ge-68 ratio of 0.95,
this would result in a 5.2% overestimation and a 1.7 % underestimation
of F-18 FDG with a Capintec and a Biodex dose calibrator, respectively.
If different dose calibrators were utilized by the radiopharmaceutical
vendor and end user, the same F-18 FDG activity would vary by 6.9
%.
Conclusions: Calibration
settings for F-18 in two commercial dose calibrator manufacturers
overestimate (5.2%) and underestimate (1.7%) F-18 FDG activity based
on a NIST traceable positron-emitting standard. Reevaluation of
F-18 calibration settings should be considered.
Keywords: Dose
calibrator | Fluorine-18 | Gallium-68 |
