4pibeta-gamma Coincidence Counting Research Articles

Standardization of 99mTc and 99Mo by the use of a 4πβ−4πγ counter

Technetium-99m is widely used for many diagnostic investigations in nuclear medicine, thus the standardization of this nuclide is important. In classical 4pibeta-gamma coincidence counting of (99m)Tc, the steep slope of the efficiency function and the large extrapolation range may cause a large measurement uncertainty. In order to overcome these difficulties, we apply the 4pibeta+4pigamma sum counting technique for the standardization. Furthermore, we adopt both the 4pibeta-4pigamma coincidence counting method and the 4pibeta+4pigamma sum counting technique for the standardization of its parent nuclide (99)Mo. High efficiencies for both nuclides were easily achieved by the use of our 4pibeta-4pigamma counter. All the results were consistent with the reference value obtained by the conventional method obtained by NMIJ.

Determination of 51Cr and 241Am X-ray and gamma-ray emission probabilities per decay

In this paper results of X-ray and gamma-ray emission probabilities per decay of (51)Cr and (241)Am are presented. The measurements were carried out by means of HPGe planar and REGe spectrometers. The activity of (51)Cr and (241)Am samples was determined in a 4pibeta-gamma coincidence counting system. The HPGe spectrometers were calibrated in a well defined geometry by means of (54)Mn, (55)Fe, (57)Co, (133)Ba, (152)Eu, (166m)Ho and (241)Am sources, previously standardized in a 4pibeta-gamma coincidence system. The MCNP Monte Carlo code was used for simulation of the REGe spectrometer calibration curve, for the selected geometry, and compared with the experimental curve. The experimental results were compared with data from literature.

Activity standardisation of 18F and ionisation chamber calibration for nuclear medicine

Primary activity standardisations were performed on solutions of (18)F using 4pibeta-gamma coincidence counting and liquid scintillation counting (LSC) according to the CIEMAT/NIST method. A beta(+)-emission probability of 96.86% was used for both methods. The various standardised (18)F solutions were measured in ionisation chambers of the Physikalisch-Technische Bundesanstalt (PTB) and compared by determining radionuclide calibration factors. Already in 2001 an (18)F solution had been standardised at the PTB and compared with the results of nine national metrology institutes (NMIs), using the ISOCAL IV secondary radionuclide calibrators of the National Physical Laboratory (NPL) as transfer instruments and a (68)Ge check source solution. These results were linked to the International Reference System (SIR) at the Bureau International des Poids et Mesures (BIPM) by aliquots of solutions sent by the Laboratoire National Henri Becquerel (BNM-LNHB) and the NPL. Further on, in 2005, PTB sent an aliquot of an (18)F solution to the SIR for ionisation chamber measurements. A value of the equivalent activity was determined and included in the key comparison database (KCDB). The recent PTB value of the equivalent activity of the SIR is in good agreement with the key comparison reference value determined from five NMIs. These results confirm that the standardisation of (18)F solutions can be achieved with the accuracy required for use in nuclear medicine and, in particular, for applications in positron emission tomography (PET).