Paul L. Ziemer

A 2π liquid scintillation counter for determining the radioactivity of large samples including man and animals

Abstract The design and operating characteristics of a 2 π large-volume liquid scintillation counter are described. The counter is used for measuring natural and tracer amounts of added radioactivity in people, animals and large samples. The detector tank, containing more than 90 gal of scintillator solution, is mounted in a horizontal position and is shielded by 6 in. of steel. The tank has a semicircular center well in which the samples are placed. This well is 72 in. long and has a 20-in. diameter. Six 16-in. dia. photomultiplier tubes provide good light collection efficiency. A conveyor system permits rapid and convenient loading and unloading of samples. The counter is currently being used to count Cs 137 and K 40 simultaneously. The counting efficiency for a Cs 137 point-source is 30.5 per cent with an average background of 13,300 counts/ min, and the counting efficiency for a 3.32 kg potassium chloride standard is 18.6 per cent with an average background of 8600 counts/min. The natural K 40 level in humans can be determined with an error of less than 2.5 per cent in a counting time of 4 min.

Distribution and clearance of63Ni administered as63NiCl2 in the rat: Intratracheal study

Microgram amounts of nickel as63NiCl2 were administered intratracheally to male rats. Regardless of time after instillation, the lungs and kidneys retained the greatest concentration of63Ni, and 21 days after dose administration they were the only organs where63Ni was still measurable. Urinary excretion was the main excretion route with 72% of the initial body burden eliminated by the urine at one day. By day 21, almost all63Ni was excreted in the urine (96.5% of the initial body burden). The lungs retained 29% of their initial (35 min) burden at day 1, decreasing to 0.1% on day 21.

Radionuclide content of and 222Rn emanation from building materials made from phosphate industry waste products.

The radionuclide content and 222Rn emanation coefficients of selected construction materials were determined. The materials were analyzed for 226Ra, 228Ra and 40K by gamma-ray spectrometry. Mineral wool insulation, which is made from Tennessee phosphate slag, and commonly used insulation, which is made from blast furnace slag, had similar concentrations of these radionuclides. Concrete blocks made with phosphate slag had enhanced 226Ra and 228Ra contents when compared to ordinary concrete block. The mineral wool insulation materials which were examined had emanation coefficients that were a few (2-6) times 10(-3). All other materials had emanation coefficients that ranged from 6 X 10(-4) to 4 X 10(-2).

A mathematical model of cadmium transport in a biological system

Abstract The research was undertaken to analyze the uptake and distribution of 109Cd in the mouse following repeated administrations and to develop a mathematical model that would describe the transport of cadmium in an animal organism. The model used was a mammillary compartmental model with the compartments corresponding to selected organs and tissues analyzed for 109Cd content. The nine-compartment model was described by first-order kinetics. From the research it was observed that no administration of cadmium was influenced by previous administrations, and this allowed the use of the same rate constants in the model for each of the multiple dosings. The linear mammillary compartmental model was able to approximate the observed laboratory values in the present investigation. The derived model was also shown to be valuable for predicting the retention of cadmium in other species without adjusting any of the rate constants.

Health physics aspects of neutron activated components in a linear accelerator.

The purpose of this study was to investigate the residual radioactivity in the therapy accessories of a medical x ray linear accelerator. The residual radioactivity mainly originated from nuclear activation reactions by neutrons, which are present as a contamination radiation in the x-ray beam. The radiation used in this study was the 25 MV x-ray beam produced by a CGR Saturne III linear accelerator. The five treatment aids include four wedges of various angles and one cerrobend block. The decrease in dose rates with time was followed for 60 min for each of the five treatment aids immediately after 999 monitor units of irradiation. The integral doses from the surface of each of four activated therapy accessories following three different radiation doses were measured by using thermoluminescent dosimeters (CaF2). In the TLD measurement, polyethylene filters were used to differentiate β− or β+ particles from the mixed decay radiation. A high-purity germanium detection system was utilized to collect and to analyze the γ spectra from the activated therapy accessories. The residual radioisotopes found in the 15° wedge and 30° wedge included 52V, 49Cr, 51Cr, 56Mn, 53Fe, 61Co, and 57Ni. In the 45° and 60° wedges, the radionuclides identified were 61Co, 57Ni, 62Cu, and 187W. The principal nuclides identified in the irradiated cerrobend block were 111mIn, 111Sn, 105Cd, 203Pb. The corresponding nuclear reactions from which the residual radionuclides produced were confirmed by consulting the current literature.

Thermoluminescence dosimetry of fast neutrons using silver activated lithium borate phosphors

Abstract A thermoluminescence dosimeter was developed consisting of a series of individual tubes of Li 2 B 4 O 7 :Ag powder covered with various thicknesses of polyethylene to enhance fast neutron response by means of increased proton recoil interactions.

A 4π liquid-scintillation whole-body counter—I. Design, operating characteristics, and calibration☆

Abstract A 4π large volume liquid-scintillation counter composed of two 2π detector tanks is described. This counter is used primarily for measuring 40 K activity in human beings and large animals.

Responsibilities and activities of the Advisory Board on Radiation and Worker Health.

As noted in the introductory editorial by Moeller and Toohey, the Energy Employees Occupational Illness Compensation Program Act (EEOICPA) was passed by the U.S. Congress in October 2000 and became effective on 31 July 2001. The Act provides a lump-sum compensation of

Uptake and distribution of cadmium in mice following repeated administrations

150,000 to workers who contracted certain diseases due to exposures to beryllium, silica, or radiation while working for the U.S. Department of Energy (DOE), its contractors, or subcontractors, in the nuclear weapons industry. The Secretaries of DOE, the U.S. Department of Health and Human Services (HHS), and the U.S. Department of Labor (DOL) share responsibilities for administering this program. In accordance with the provisions of EEOICPA, the President, in October 2001, appointed an Advisory Board on Radiation and Worker Health. The work of the Board, which began in January 2002, is conducted with staff support provided by the National Institute for Occupational Safety and Health (NIOSH). NIOSH is responsible for establishing scientific guidelines for determining whether a worker’s cancer is “at least as likely as not” related to occupational exposure to radiation (probability of causation) and developing methods to estimate worker exposure to radiation (dose reconstruction). During its first 5 years of operation, the Board has provided substantial input on the rulemaking activities of NIOSH. It also is establishing methodologies for auditing the validity and quality of the dose estimates. The Board expects to sample and examine approximately 2–3% of the completed dose reconstructions. Random audits of approximately 1% of these are now underway.

Thermoluminescence and microwave induced thermoluminescence fading of rare-earth-doped barium titanate ceramics

The research was undertaken to analyze the uptake and distribution of cadmium-109 in mice following repeated injections and to observe how the simultaneous administrations of zinc affected the cadmium retention. Mice were given one, two, or three intravenous administrations at 48-hr intervals. Animals were sacrificed 2 min to 48 hr after each injection. Zinc had little effect on the retention of cadmium in the samples analyzed, and injections behaved independently of each other.