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Biomedical subjects

C S Sims

Publications and source records attributed to C S Sims.

15 recordsLinked to original sources
PubMed1992

Modification of neutron-induced hematopoietic effects by chemical radioprotectors.

Nine drugs, WR-347, WR-1065, WR-2529, WR-2721, WR-3689, WR-44923, WR-151327, WR-109342, and WR-168643, were assayed for intraperitoneal pharmacological toxicity, hematopoietic lethality, and spleen stem cell survival in C57/Bl mice in conjunction with whole-body fission neutron irradiation. In addition, WR-3689, WR-109342, and WR-168643 were used with per os administration to determine hematopoietic lethality. Drug toxicities after intraperitoneal administration, as determined by LD50's, ranged from 37 mg/Kg for WR-109342 to 2901 mg/Kg for WR-2529. Following oral administration drug toxicities ranged from 58 mg/Kg (WR-109342) to 1816 mg/Kg (WR-3689). Dose modification factors as determined by LD50(30)'s following intraperitoneal administration ranged from 1.08 for WR-347 to 1.49 for WR-2529. Of the drugs orally administered, WR-168643 was the best protector with a DMF of 1.51. Spleen stem cell survival, which was performed only after intraperitoneal drug administration, provided no significant differences in dose modification factors.

Animals↗
PubMed1992

Summary statements from the Third Conference on Radiation Protection and Dosimetry.

The Third Conference on Radiation Protection and Dosimetry was conducted in Orlando, FL, on 21-24 October 1991. At the end of the conference, each member of the Technical Program Committee summarized the events considered to be of particular importance. Subjects discussed included dosimetry accreditation programs, regulations, standards, compliance, advances in dosimeters and instrumentation, training, needs in metrology, and funding of dosimetry research. These statements have been collected and combined and are presented as a brief summary of the conference.

Radiation Protection↗
PubMed1992

A proposed four-element neutron-photon-beta thermoluminescence dosimeter.

It is common practice for a worker exposed to a mixed field with neutrons to wear both a photon-beta dosimeter and a neutron dosimeter. In this study, a thermoluminescence dosimeter has been designed and is proposed for use in mixed fields. The maximum applicable ranges of the mixed field can have photons with unknown energy from 20 keV to 2 MeV, betas with unknown energy from 147Pm to 90Sr-Y, and neutrons of known energy from thermal to 15 MeV. This proposed dosimeter (a combination of Harshaw beta-gamma thermoluminescence dosimeter and albedo neutron thermoluminescence dosimeter) has an advantage of using a minimum number of thermoluminescence dosimeter elements (therefore, making it less costly) to measure the dose equivalents in a mixed field of neutron, photon, and beta radiation. The basic dosimeter design consists of four thermoluminescence elements of TLD-600 and TLD-700 with different filtrations. Using the high-temperature peak methodology for TLD-600 and a filtration algorithm, the neutron, photon, and beta dose equivalents in a mixed field can be determined. The design, detection principle, and three dosimetric algorithms for three versions of the basic design of the four-element dosimeter are presented and discussed. The work that is required for the proposed dosimeter to be usable when it is made is also presented.

Algorithms↗
PubMed1992

Neutron dosimetric quantities for several radioisotopic neutron sources.

The fluence-weighted and dose equivalent-weighted average energies, and the spectrum-averaged fluence-to-dose equivalent conversion factors have been calculated for 52 spectrum variations of 20 different radioisotopic neutron sources. An internally consistent method of determination enables comparison of values for different spectra. The methodology and results are presented.

Neutrons↗
PubMed1989

Nuclear accident dosimetry intercomparison studies.

Twenty-two nuclear accident dosimetry intercomparison studies utilizing the fast-pulse Health Physics Research Reactor at the Oak Ridge National Laboratory have been conducted since 1965. These studies have provided a total of 62 different organizations a forum for discussion of criticality accident dosimetry, an opportunity to test their neutron and gamma-ray dosimetry systems under a variety of simulated criticality accident conditions, and the experience of comparing results with reference dose values as well as with the measured results obtained by others making measurements under identical conditions. Sixty-nine nuclear accidents (27 with unmoderated neutron energy spectra and 42 with eight different shielded spectra) have been simulated in the studies. Neutron doses were in the 0.2-8.5 Gy range and gamma doses in the 0.1-2.0 Gy range. A total of 2,289 dose measurements (1,311 neutron, 978 gamma) were made during the intercomparisons. The primary methods of neutron dosimetry were activation foils, thermoluminescent dosimeters, and blood sodium activation. The main methods of gamma dose measurement were thermoluminescent dosimeters, radiophotoluminescent glass, and film. About 68% of the neutron measurements met the accuracy guidelines (+/- 25%) and about 52% of the gamma measurements met the accuracy criterion (+/- 20%) for accident dosimetry.

Accidents↗
PubMed1988

Neutron personnel dosimetry intercomparison studies at the Oak Ridge National Laboratory: a summary (1981-1986).

To provide an opportunity for dosimetrists to test and calibrate their neutron personnel monitoring systems, the staff of the Dosimetry Applications Research (DOSAR) Facility at the Oak Ridge National Laboratory (ORNL) has conducted personnel dosimetry intercomparison studies (PDIS) periodically since 1974. During these studies, personnel dosimeters are mailed to ORNL, exposed to low-level (less than 15 mSv) neutron dose equivalents in a variety of mixed-radiation fields, and then returned to the participants for evaluation. These intercomparisons have provided more data on neutron dosimeter performance than any other periodic test program conducted to date. This report presents a summary and analysis of about 3450 neutron dose equivalent measurements reported for PDIS 7 through 12 (1981-1986) with emphasis on low dose equivalent sensitivity, accuracy and precision, and performance relative to accreditation standards for the basic types of personnel dosimetry systems. Relationships of the PDIS results to occupational neutron monitoring, accreditation testing, and methods to improve personnel neutron dosimetry performance are also discussed.

Environmental Exposure↗
PubMed1982

Personnel dosimetry intercomparison studies at the Health Physics Research Reactor: a summary (1974-80).

Six personnel dosimetry intercomparison studies using the Health Physics Research Reactor at the Oak Ridge National Laboratory were conducted between 1974 and 1980. These studies allowed participants to test their neutron and gamma-ray dosimeters under a variety of mixed-field spectral conditions and to compare their results with those of others making measurements under identical conditions. Fifty-eight participant organizations, about half of which participated in more than one study, made approx. 2000 measurements of the neutron and gamma-dose-equivalent. Dose equivalents in the 0.1-12 mSv (i.e. 10-1200 mrem) range were determined for five different shielded reactor spectra using three basic types of dosimeters (thermoluminescent albedo, nuclear emulsion film and track etch) for neutron measurements and two basic types (film and thermoluminescent dosimeters) for the gamma-measurements. The data from the six studies are summarized, analyzed and explained. Intercomparison of the participants' results and consideration of reference dosimetry allows several conclusions to be made relative to the status of and trends in personnel neutron and gamma-ray dosimetry.

Film Dosimetry↗