Speaker
Description
The Radionuclide Metrology (RM) group at ANSTO maintains the Primary Standard for Activity of Radionuclides for Australia. To support measurement accuracy in nuclear medicine, RM develops primary standards for radioisotopes significant for their role in patient imaging and treatment. In particular, Tc-99m, I-131 and Lu-177, which are produced using the Open Pool Australian Lightwater (OPAL) reactor and make up the majority of nuclear medicine procedures in Australia. Primary Standards have been developed for these radionuclides by applying the 4πβ-γ coincidence method. International measurement traceability was established by participation in key comparisons, specifically APMP.RI(II)-K2.I-131, CCRI(II)-K2.Lu-177 and BIPM-RI(II)-K4.Tc-99m.
To enable the dissemination of Primary Standards, RM maintains a Secondary Standard Ionisation Chamber (SSIC) for which radionuclide-specific calibration factors are developed during primary standard campaigns. In addition to the widely used measurement geometry of 3.6 mL in a glass ampoule, RM develops calibration factors for measurement geometries routinely used in clinical settings. Applying sources prepared in these geometries for calibration provides more relevant instrument settings than simply adopting the manufacturer's specification.
ANSTO developed the Australian Nuclear Medicine Traceability Program (ANMTP) in consultation with the Australian and New Zealand Society of Nuclear Medicine. Following a successful pilot in 2014, ANSTO have provided opportunity for Nuclear Medicine Departments to access the Australian Standard in the same measurement geometries used for distribution of radiopharmaceuticals. The program is run in October-December each year and includes on-site measurements of Certified Reference Materials in Hospital dose calibrators. Results are recorded using a custom-designed tablet application, allowing measurements to be time stamped and discrepancies calculated in real time. There is then the opportunity for the instrument calibration factor(s) (or dial setting) to be adjusted to minimise any discrepancy. Results are subsequently reported to clients. ANSTO has successfully executed eight of these measurement campaigns, with a ninth planned for late 2022. Thirty-nine departments have gained access to the Australian Standard through this program, from six States and Territories.
The consistent manner in which data is collected allows trends to be identified year on year. Where drift is identified for an instrument, departments are provided with an awareness of the behaviour of their instrument. For older instruments, this is of particular importance as manufacturers will routinely decline to support models which are no longer produced.
Acknowledgements:
1.We acknowledge the contribution of B Caruana, who worked to set up this program.
2.L Mo and L Bignell developed the Lu-177 and I-131 primary standards.
