Dispensing Therapeutic Amounts of Holmium-166 with a Radionuclide Calibrator

Abstract

Objective: A high-purity germanium detector (HPGe) spectrometry system was used to calibrate a radionuclide calibrator for the accurate dispensing of therapeutic amounts of ¹⁶⁶Ho to be administered to patients.

Methods: A calibrated ⁶⁰Co source was counted simultaneously in the same geometry as the ¹⁶⁶Ho for acquisition of gamma ray spectra. The sensitivity of the HPGe detector for the 1.379-MeV photons emitted by ¹⁶⁶Ho was determined from the 1.333-MeV photons emitted from ⁶⁰Co. This measured amount of ¹⁶⁶Ho was placed in an assay calibrator and the sensitivity control adjusted so that the readout matched the ¹⁶⁶Ho content.

Results: The dial setting required for the Capintec CRC-15R was found to be 748 times 10.

Conclusion: This assay of ¹⁶⁶Ho with a HPGe detector has proved useful for adjusting the sensitivity of a clinical radionuclide calibrator and can be extended to provide calibration factors for other assay calibrators used to dispense therapeutic amounts of other radionuclides used for clinical nuclear medicine procedures.