A Mobile Bioassay Laboratory for the Assessment of Internal Doses Based on in Vivo and in Vitro Measurements

Abstract

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.

Review of methods to measure internal contamination in an emergency

“…The DL for 137 Cs in whole body for the former system is 5000 Bq and 100 Bq for the latter for a 10 min count time. Details of other shielded NaI(Tl) detector based systems with similar characteristics to those described above have been published by Dantas et al (2010), Mizushita (1977) and Summering (1980). The National Radiological Protection Board (now part of PHE) developed and built a transportable whole body monitoring system (Youngman 2001).…”

Assessment of Applicability of Portable HPGe Detector with In Situ Object Counting System based on Performance Evaluation of Thyroid Radiobioassays

“…Radioactive sources are widely used in nuclear power, nuclear medicine, radiopharmaceutical production, and research laboratories. However, their use can lead to health problems in occupational workers and the public via radiation or radionuclides entering the body through various routes such as inhalation, ingestion, skin absorption, and wound absorption [1][2][3][4][5][6]. Thus, it is necessary to prepare appropriate mea-JRPR surement methods and equipment for assessing the internal radiation dose in case of a radiation accident [6].…”

“…Internal contamination in the thyroid gland is generally detected using a thyroid monitoring system. Typically, thyroid monitoring involves a type of gamma spectroscopy that measures gamma-emitting radionuclides in the sample [1,9]. A typical thyroid monitor for radiobioassays is a detector with NaI(Tl) scintillation material.…”

An experimental study of detection limits and corresponding doses of IRSNin vivomonitoring vehicles in the case of post-accident scenarios

“…Several mobile laboratories have been developed all over the world (Boddy, 1967;Hille et al, 2000;Bondarkov et al, 2001;Castagnet et al, 2007;Dantas et al, 2010). The French Institute for Radiological protection and Nuclear Safety (IRSN) has updated the former SCPRI fleet of Mobile Units (MUs) dedicated to emergency situations (Pellerin and Moroni, 1969).…”