Cherenkov counting of yttrium-90 in the dry state; correlations with phosphorus-32 Cherenkov counting data

Rapid screening methods for beta-emitters in food samples

In case of a nuclear emergency, many samples need to be measured in a short time period. Therefore, it is of vital importance to have a quick and reliable (screening)method. Most methods to determine total beta activity are time-consuming because of extensive sample preparation, such as ashing. In this article three different rapid screening methods for beta emitting nuclides in agriculture, livestock and fishery products were tested and compared to each other, and to an accurate but more time consuming reference method. The goal was to find the method with the optimal trade-off between accuracy, speed and minimal detectable activity (MDA). All of the methods rely on liquid scintillation counting (LSC) or Cerenkov counting, and differ mainly in sample preparation. For matrices with little or no colour, the direct LSC-method is the most accurate and fastest option, while for darker coloured samples this method is not suitable because of high colour quenching. For such samples, two additional methods using a microwave digestion during sample preparation, produced good results.

Fast determination of ⁹⁰Sr/⁹⁰Y activity in milk by Cherenkov counting

Cherenkov counting of the ⁹⁰Sr/⁹⁰Y pure beta emitters is an attractive method for ⁹⁰Sr activity determination, but the color quenching effect may be significant, especially for strongly colored or semi-opaque media. A quench correction method based on the external source of some liquid scintillation systems (named ESAR - external source area ratio) was proposed and checked for aqueous solutions and was proved to be effective also for urine samples. In the present work, the application of the ESAR method for fast determination of ⁹⁰Sr/⁹⁰Y activity in milk samples is described.

Radiopharmaceutical management of90Y/111In labeled antibodies: shielding and quantification during preparation and administration

BACKGROUND

The combined application of potent beta-emitting isotopes for therapy with remitting isotopes for scintigraphy requires a profound regimen concerning team member safety and radionuclide quantification.

METHODS

We have developed materials and methods for a proper and easy manipulation of 90Y during preparation and administration of 90Y/111In pharmaceuticals used for radioimmunotherapy.

RESULTS

The efficacy of the shielding measures is documented. Protocols for the calibration of gamma-dose calibrators with respect to 90Y are extended to the assessment of quench-corrected liquid scintillation counting of 90Y. The contribution of 90Y backscatter to 111 In counting is quantified. Newly developed shielding equipment allows an adequate administration of relatively large volumes (100 ml) of 90Y/111In labeled pharmaceuticals to patients.

CONCLUSIONS

The procedures described combine pharmaceutical (Good Manufacturing Practice) and radiation safety requirements with an accurate logging of relevant data.

Cerenkov counting of low-energy beta-emitters using a new ceramic with high refractive index

The threshold beta-ray energy for Cerenkov photon production can be reduced to about 0.07 MeV by using a transparent ceramic with a high refractive index. This makes it possible to measure the low-energy beta-emitters 14C and 45Ca by Cerenkov counting with efficiencies of 1.5% and 2.3%, respectively.