The international reference system for beta-particle emitting radionuclides: Validation through the pilot study CCRI(II)-P1.Co-60

The Bureau International des Poids et Mesures (BIPM) is developing a new transfer instrument to extend its centralized services for assessing the international equivalence of radioactive standards to new radionuclides. A liquid scintillation counter using the triple/double coincidence ratio method is being studied and tested in the CCRI(II)-P1.Co-60 pilot study. The pilot study, involving 13 participating laboratories with primary calibration capabilities, validated the approach against the original international reference system based on ionization chambers, which has been in operation since 1976. The results are in agreement and an accuracy suitable for purpose, below 5×10-4, is achieved. The pilot study also reveals an issue when impurities emitting low-energy electrons are present in the standard solution, which have a different impact on liquid scintillation counting compared to other primary measurement methods.

14 MeV Neutrons for 99Mo/99mTc Production: Experiments, Simulations and Perspectives

Background: the gamma-emitting radionuclide Technetium-99m (^99mTc) is still the workhorse of Single Photon Emission Computed Tomography (SPECT) as it is used worldwide for the diagnosis of a variety of phatological conditions. ^99mTc is obtained from ⁹⁹Mo/^99mTc generators as pertechnetate ion, which is the ubiquitous starting material for the preparation of ^99mTc radiopharmaceuticals. ⁹⁹Mo in such generators is currently produced in nuclear fission reactors as a by-product of ²³⁵U fission. Here we investigated an alternative route for the production of ⁹⁹Mo by irradiating a natural metallic molybdenum powder using a 14-MeV accelerator-driven neutron source. Methods: after irradiation, an efficient isolation and purification of the final ^99mTc-pertechnetate was carried out by means of solvent extraction. Monte Carlo simulations allowed reliable predictions of ⁹⁹Mo production rates for a newly designed 14-MeV neutron source (New Sorgentina Fusion Source). Results: in traceable metrological conditions, a level of radionuclidic purity consistent with accepted pharmaceutical quality standards, was achieved. Conclusions: we showed that this source, featuring a nominal neutron emission rate of about 10¹⁵ s⁻¹, may potentially supply an appreciable fraction of the current ⁹⁹Mo global demand. This study highlights that a robust and viable solution, alternative to nuclear fission reactors, can be accomplished to secure the long-term supply of ⁹⁹Mo.

Evaluation of the radon interference on the performance of the portable monitoring air pump for radioactive aerosols (MARE)

A compact portable aerosol sampling and measurement device was developed at Jožef Stefan Institute (JSI). A CeBr₃ scintillation detector is positioned centrally within a concertinaed filter assembly. It provides continuous and via network communications on-line monitoring of low levels of airborne radioactive particulates. The evaluation of the response of the device to the natural background at controlled conditions with elevated radon concentrations, performed at the National Institute of Ionizing Radiation Metrology of ENEA, is presented.

(18)F primary standard at ENEA-INMRI by three absolute techniques and calibration of a well-type IG11 ionization chamber

A new (18)F primary standardization carried out at ENEA-INMRI by three different absolute techniques, i.e. 4πγNaI(Tl)γ high-efficiency counting, TDCR and 4πβ(LS)-γ[NaI(Tl)] coincidence counting method, allowed the calibration of a fixed well-reentrant IG11 ionization chamber (IC), with an uncertainty lower than 1%, and to check the calibration factor of a portable well-type IC NPL-CRC model, previously calibrated. By the new standard the ENEA-INMRI was linked to the BIPM International Reference System (SIR) through the BIPM SIR Transfer Instrument (SIRTI).

A prototype of a portable TDCR system at ENEA

A prototype of a portable liquid scintillation counting system based on the Triple-to-Double Coincidence Ratio (TDCR) technique was developed at ENEA-INMRI in the framework of the European Metrofission project. The new device equipped with the CAEN digitizers was tested for the activity measurements of pure β-emitters ((99)Tc and (63)Ni). The list-mode data recorded by the digitizers were analyzed by software implemented in the CERN ROOT environment, which allows the application of pulse shape discrimination using the new device.

Experimental determination of the radionuclide calibrator setting for Technesium-99m, by using a primary standardisation method

BACKGROUND

A new 99mTc national standard has been developed at the Italian National Metrology Institute for Ionizing Radiation quantities of ENEA (ENEA-INMRI).

METHODS

The stock radioactive solution was prepared at the Ospedale Pediatrico Bambino Gesù (OPBG) and standardized at the ENEA-INMRI by using the 4pigamma absolute measurement method. The new standard was used to calibrate the dose calibrator of the OPBG Nuclear Medicine Unit (NMU) and the ENEA-INMRI portable ionization chamber which was employed as the secondary standard measurement system to calibrate the dose calibrator of another Italian nuclear medicine unit.

RESULTS AND CONCLUSION

Remarkable improvement of measurement accuracy was achieved. The importance of traceable calibrations is underlined. Specific comments are made about quality control performance and measurement accuracy for the instrumentation used in nuclear medicine units of paediatric hospitals.