A new approach for the determination of 210Pb by liquid scintillation counting.

A new approach to the calibration procedure is presented, as there is no need to discount bismuth from lead spectrum when constructing the efficiency curve. This work presents two calibration methods: one considering mostly lead spectrum contributions and other that considers both lead and bismuth contributions. Both methodologies provide consistent results when evaluated in an intercomparison program. Furthermore, this methodology allows simultaneous analysis of several samples and is suitable for any type of sample after proper digestion in liquid form.

A mobile bioassay laboratory for the assessment of internal doses based on in vivo and in vitro measurements.

Internal exposures may occur in nuclear power plants, radioisotope production, and in medicine and research laboratories. Such practices require quick response in case of accidents of a wide range of magnitudes. This work presents the design and calibration of a mobile laboratory for the assessment of accidents involving workers and the population as well as for routine monitoring. The system was set up in a truck with internal dimensions of 3.30 m × 1.60 m × 1.70 m and can identify photon emitters in the energy range of 100-3,000 keV in the whole body, organs, and in urine. A thyroid monitor consisting of a lead-collimated NaI(Tl)3" × 3" (7.62 × 7.62 cm) detector was calibrated with a neck-thyroid phantom developed at the IRD (Instituto de Radioproteção e Dosimetria). Whole body measurements were performed with a NaI(Tl)8" × 4" (20.32 × 10.16 cm) detector calibrated with a plastic-bottle phantom. Urine samples were measured with another NaI(Tl) 3" × 3" (7.62 × 7.62 cm) detector set up in a steel support. Standard solutions were provided by the National Laboratory for Metrology of Ionizing Radiation of the IRD. Urine measurements are based on a calibration of efficiency vs. energy for standard volumes. Detection limits were converted to minimum committed effective doses for the radionuclides of interest using standard biokinetic and dosimetric models in order to evaluate the applicability and limitations of the system. Sensitivities for high-energy activation and fission products show that the system is suitable for use in emergency and routine monitoring of individuals under risk of internal exposure by such radionuclides.

Methodology for radionuclides quantification through "in vitro" bioassay.

In Brazil, the radionuclides used for therapy are: (131)I, (153)Sm, (90)Y and (177)Lu, both for routine or research protocols. The radionuclide activity excreted by patients may be quantified by bioassay analysis and constitutes a powerful tool for individual treatment planning. The Bioassay Laboratory (LBIOVT) of the Institute of Radiation Protection and Dosimetry (IRD) has equipments for gamma and beta spectroscopy. These systems are calibrated in energy and efficiency using reference sources supplied by the National Laboratory of Radiation Metrology (LMNRI/IRD). The LBIOVT has operational procedures according ISO-ABNT-17025 recommendations and participates of international and national intercomparisons. The patient samples are collected immediately after radiopharmaceutical administrations, at the hospital or at the patient residence, and are handled, stored and transported according national radiation protection regulations. The radionuclide specific activity (Bq/L) is referenced to date and time of excretion, for the estimation of the individual biological half-live. The volume of excreta may carefully manipulated in order to avoid losses and misinterpretation in the activity quantification. The process of the LBIOVT accreditation and its participation in intercomparisons may guarantee the confidence of the results, allowing the minimization of the uncertainties in the individual monitoring.

Lidocaine excretion in breast milk.

Nursing mothers are occasionally treated with intravenous lidocaine for ventricular dysrhythmias. There have been no reports on the excretion of lidocaine into breast milk. This case documents the excretion of lidocaine into breast milk in small amounts and shows the validity of the TDx methodology used in the whole-milk lidocaine assay. We observed breast-milk concentrations of lidocaine at 40 percent of the serum levels. Clinical practitioners should be aware the lidocaine is excreted into breast milk in small amounts and the mother could probably continue to safely breast-feed her child while on parenteral lidocaine. Any adverse reactions in the nursing infant would probably be limited to an idiosyncratic or allergic reaction.