radionuclide metrology-SIRTI

SIRTI – SIR Transfert Instrument

The BIPM offers an on-site comparison service for short-lived gamma-emitting radionuclides. Samples of the radionuclides are measured with a stable and highly reproduceable transfer instrument and the results compared to those from other NMIs and DIs. The transfer instrument is a well-type NaI(Tl) detector.

The BIPM organizes the transport of the SIRTI instrument to and from the NMI/DI, and work with NMI/DI staff on-site to carry out the measurements. A remote control of the SIRTI from the BIPM is used when possible. Participants are invited to compare several radionuclides at once.

The SIRTI is linked to the SIR when practicable. The results are reported on the Key Comparison Database and can be part of the evidence needed by the independent assessors approving claims for Calibration and Measurement Capabilities.


Radionuclides covered 11C, 13N, 18F, 56Mn, 64Cu, 99mTc, 123I, 153Sm
BIPM comparator High-precision scintillation counter
Quantity compared Activity / Bq
Level From 10 kBq to 150 kBq (radionuclide dependent)
Uncertainty of comparator Depends on the radionuclide, typically 0.15% (k = 2)
plus, when appropriate, the uncertainty of the link to the SIR of typically 0.3 % (k = 2)
Comparison service identifier BIPM.RI(II)-K4
Underpins equivalence for... Radionuclides set out in the MMM
Validity Results remain valid for 15 years
Key comparison reference value Power-moderated weighted mean of results (from the corresponding SIR comparison when appropriate)


Guidance document MMM

How to participate - SIRTI

How to participate


SIR/SIRTI reporting form - radioactive solution


SIR Transfer Instrument - Protocol for the continuous activity comparisons at the NMIs - BIPM.RI(II)-K4



Dr Carine Michotte

Ionizing Radiation Department

radionuclide metrology - KCDB