Calibration setting numbers for dose calibrators for the PET isotopes 52Mn, 64Cu, 76Br, 86Y, 89Zr, 124I

Abstract

For PET radionuclides, the radioactivity of a sample can be conveniently measured by a dose calibrator. These devices depend on a "calibration setting number", but many recommended settings from manuals were interpolated based on standard sources of other radionuclide(s). We conducted HPGe gamma-ray spectroscopy, resulting in a reference for determining settings in two types of vessels containing one of several PET radionuclides. Our results reiterate the notion that in-house, experimental calibrations are recommended for different radionuclides and vessels.

Monte Carlo calculated calibration settings for commercially available nuclear medicine ionization chambers

“…The activity read out using the NIST measured calibration setting is of the order $$20\%$$ larger than that measured in this work. Capintec R series calibration settings for $$^{124}$$I measured by Beattie et al and Wooten et al 3,4 . both show discrepancies with the NIST measurement similar in magnitude to those presented in this work.…”

“…While previously published work has demonstrated independent validation of calibration settings with HPGe detector spectroscopy 1–4 , taking a Monte Carlo approach to characterizing the efficiency of the detector eliminates the need for the standard source to have a calibrated photopeak at a desired energy, rather it requires only sufficient sampling of a photopeak within a validated energy range. While a standardized $$^{68}$$Ge source provides a means of validating calibration settings for positron emitting isotopes, it cannot be directly extended to general nuclear medicine isotopes, in particular general therapeutic isotopes for which hypothetical discrepancies in calibration settings as large as $$20\%$$ like those reported in the literature for $$^{124}$$I 3,4,10 or $$^{86}$$Y 4 could result in an administration of activity discrepant from the prescribed activity to the extent of a reportable incident.…”

“…A more practical approach is using a primary standard source in a replicable geometry to characterize the photon detection efficiency (PDE) of a high-resolution spectroscopic detector such as a high purity germanium (HPGe) detector, and performing relative activity quantitation. Reference measurements made with HPGe detector spectroscopy were employed by Wooten et al 4 and Beattie et al 3 to derive calibration settings for a range of positron emitting isotopes and successfully highlighted inaccuracies in manufacturer recommendations. A more comprehensive approach of characterizing the PDE of the detector with Monte Carlo modeling provides a means of accurately interpolating the PDE over a validated energy range for various extended source geometries and accounts for each isotope-specific PDE at 511 keV due to differences in beta spectra.…”

“…A more practical approach is using a primary standard source in a replicable geometry to characterize the photon detection efficiency (PDE) of a high‐resolution spectroscopic detector such as a high purity germanium (HPGe) detector, and performing relative activity quantitation. Reference measurements made with HPGe detector spectroscopy were employed by Wooten et al 4 . and Beattie et al 3 .…”

Quantitative PET-Bildgebung für die Dosimetrie an Beispielen von 124I, 86Y, 68Ga und 44Sc

“…Darüber hinaus ist auch die Abhängigkeit vom Material des Probengefäßes (Spritze, Kapsel, Glasampulle) zu beachten. Dies gilt insbesondere für 124 I und 86 Y, die einen hohen Anteil an Röntgenstrahlung emittieren [13,78].…”