Radioactivity was measured in a dose calibrator cross-calibrated to the PET scanner (Isomed 2000, Med Nuklear Medizintechnik, Germany).
SUV computation thus requires quantitative determination of the tracer concentration with PET which in turn necessitates a regularly performed thorough scanner calibration (and cross-calibration against a dose calibrator) based on suitable phantom measurements adhering to standardized procedures [2, 4 6].
PET image counts were calibrated to a dose calibrator to convert measured PET uptake to MBq of F-18.
Samples of blood and various tissues were excised, patted dry, weighed, and measured for radioactivity using an automatic gamma counter (1480 Wizard 3" Gamma Counter; EG & G Wallac, Turku, Finland) cross-calibrated with a dose calibrator (VDC-202, Veenstra Instruments, Joure, The Netherlands).
These are: normalization, correction for random coincidences, correction for scattered radiation, correction for dead time and cross-calibration with a dose calibrator or well counter.
First, it eliminates a common source of error – the need for precise cross-calibration between a dose calibrator and the PET scanner.
In conventional measurement of the SA of a radiotracer, the detector giving the mass response is calibrated for compound mass, and the radioactivity associated with a particular carrier mass peak is measured in a calibrated detector, invariably a dose calibrator (an ionization detector).
After separation of 43Sc from the 46Ti and 43CaCO3 target material, the activity of the obtained eluate was quantitatively determined with a dose calibrator (ISOMED 2010, Nuclear-Medizintechnik Dresden, GmbH, Germany – calibrated on a fortnightly basis).
Specifically, the output voltage from the radiation detector was calibrated to known radioactivity concentration, as measured by a dose calibrator and a precision scale.
Activity injected in phantoms was measured with a dose calibrator (ACAD 2000, Lemer Pax, Carquefou, France) that was initially calibrated using a reference 124I source provided by IBA (Amsterdam, The Netherlands).
