Development of a calibration methodology for large-volume, solid ⁶⁸Ge phantoms for traceable measurements in positron emission tomography.

We have developed a methodology to calibrate the (68)Ge activity concentration in large (9L) cylindrical epoxy phantoms in a way that is traceable to national standards. The method was tested on two prototype cylindrical phantoms that are being used in a clinical trial and gave (68)Ge activity concentration values with combined standard uncertainties of about 1.1%. Imaging data from the phantoms using a calibrated PET-CT scanner gave values consistent with the calibrated activity concentrations within experimental uncertainties.