Standardization of Ni-63 by 4 pi beta liquid scintillation spectrometry with H-3-standard efficiency tracing

Abstract

The low energy (Eβmax = 66.945 keV ± 0.004 keV) β-emitter 63Ni has become increasingly important in the field of radionuclidic metrology. In addition to having a low β-endpoint energy, the relatively long half-life (101.1 a ± 1.4 a) makes it an appealing standard for such applications. This paper describes the recent preparation and calibration of a new solution Standard Reference Material of 63Ni, SRM 4226C, released by the National Institute of Standards and Technology. The massic activity CA for these standards was determined using 4πβ liquid scintillation (LS) spectrometry with 3H-standard efficiency tracing using the CIEMAT/NIST method, and is certified as 50.53 kBq ·g−1 ± 0.46 Bq · g−1 at the reference time of 1200 EST August 15, 1995. The uncertainty given is the expanded (coverage factor k = 2 and thus a 2 standard deviation estimate) uncertainty based on the evaluation of 28 different uncertainty components. These components were evaluated on the basis of an exhaustive number (976) of LS counting measurements investigating over 15 variables. Through the study of these variables it was found that LS cocktail water mass fraction and ion concentration play important roles in cocktail stability and consistency of counting results. The results of all of these experiments are discussed.

Toxicity and dosimetry of177Lu-DOTA-Y3-octreotate in a rat model

“…Due to the short half-life of 176m Lu and the delivery time for the isotope, its contribution to the absorbed dose estimates was not considered. The 0.02% presence of 177m Lu, a value recently confirmed and published by the NIST, 8 was considered, but the dose contribution of this contaminant was not included in our dosimetry calculations. It was assumed that this small impurity would only alter the absorbed dose estimates to the second decimal place and was easily within the reported standard deviations of the estimated absorbed doses.…”

“…An alternative radionuclide for targeted radiotherapy is 177 Lu (t 1/2 ϭ 6.65 d), 8 10 In patients with ovarian cancer, the 177 Lu-labeled monoclonal antibody (Mab) CC49 showed considerable efficacy at controlling micrometastatic disease. 11 The groups at the University of Rotterdam and Mallinckrodt, Inc. have evaluated 177 Lu-labeled somatostatin analogs in a tumor-bearing rat model and demonstrated impressive therapeutic efficacy.…”

Recommendations of the American Association of Physicists in Medicine on dosimetry, imaging, and quality assurance procedures for 90Y microsphere brachytherapy in the treatment of hepatic malignancies

“…Due to the high efficiency of the method, approximately 98% for 90 Y, liquid-scintillation (LS) counting is routinely used for activity measurements of beta-emitting radionuclides in solution. Two different methods may be used to determine the efficiency: the CIEMAT=NIST (Centro de Investigaciones Energeticas, Medioambientales y Technologicas) efficiency tracing method 46,47 or the Triple-to-Double Coincidence Ratio method. 48 Both of these methods are used at NIST.…”

Combined effect of gamma-radiation and pH on corrosion of Ni–Cr–Fe alloy inconel 600

“…Uniform corrosion introduces dissolved metal impurities in the reactor coolant and their accumulation can lead to the formation of insoluble metal oxide particulates and deposits in the coolant system. In the reactor core stable isotopes can absorb a neutron and become radioactive (e.g., forming 54 Mn, 58 Co, 59 Fe, 60 Co, or 58 Ni) [1][2][3]. Deposition of radioactive materials on coolant system components outside of the biological shielding of the reactor core creates a potential source of radiation exposure for plant workers.…”