Schweizerische Radionuklid Referenzkammern: IRA CIR II und METAS TCIR

• Forschungsstelle: METAS
• Projektnummer: F-5155.30014
• Projekttitel Englisch: Swiss reference chamber for radioactivity: IRA CIR II and METAS TCIR

Schlüsselwörter (Englisch)

Radioactivity, reference ionization chamber, nuclear medicine, dose calibrators, secondary standard, activity measurement, becquerel

Kurzbeschreibung (Englisch)

The primary standard realization of radioactivity requires specific realizations for each individual isotope, the method determined by the decay scheme and nature of the isotope. For this reason, primary standard laboratories operate a secondary reference ionization chamber with a very high long term stability. There the isotope specific activities in Becquerel, determined beforehand by truly primary measurements, are stored as relative ionization current values. The scope of the project is to develop both a  new Swiss secondary reference chamber for radioactivity at IRA and a transportable version for METAS for calibration of dose calibrators at the nuclear medicine institutes.

Projektziele (Englisch)

Development of a new Swiss secondary reference chamber for radioactivity (CIR) and a transportable version for METAS (TCIR). Determination of calibration factors for new radioisotopes at nuclear medicine institutes and improvement of uncertainty of calibration factors owing to on site calibrations.

Abstract (Englisch)

The TCIR is completed and the first measurements on site have demonstrated that it is fully operational. It can be used for several isotopes of short half-life (Tc-99m, F-18, C-11, O-15, N-13) but also can be calibrated for other isotopes on demand. The traceability is obtained using the CIR and the final standard relative uncertainty is better than 1%. Several measurements have been performed to validate the operation of the TCIR at IRA with calibrated sources and clinical measurements on site at CHUV. All have proved TCIR’s good operation on the field, and it is now ready to do its work of measuring short half-life isotopes on site and will provide a novel and relevant tool to METAS.

The CIR II has been built and tested. A new acquisition system has been developed as well as new containers for the reference sources which use a new isotope Ho-166m. However, an unexpected level of impurities in the Ho-166m solution has greatly delayed the whole manufacturing of the reference sources. The solution is currently in the purification process and the reference sources will be realized quickly. Nevertheless and as expected, the validation will be completed slowly taking advantage of the submission and measurements performed on the old CIR.

Umsetzung und Anwendungen (Englisch)

The first tests in real conditions of the TCIR are successful and showed an interesting potential for future services, which could be offered to the clinical community by METAS.

The CIR II is operational and the long procedure of validation towards the CIR is ongoing. This instrument is clearly meant to be the next Swiss reference and it will be systematically compared to the CIR, which is the keeper of the Swiss Calibration and Measurement Capabilities in the field of radioactivity.

Publikationen / Ergebnisse (Englisch)

1. Nedjadi et al., “A new measurement of the half-life of ^166mHo”, Applied Radiation and Isotopes 70 (2012)1990-1996.
2. Bailat et al., “Development, design and validation of solid reference samples”, Applied Radiation and Isotopes 87 (2014) 480-484.