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Biomedical subjects

H V Piltingsrud

Publications and source records attributed to H V Piltingsrud.

At least 19 recordsLinked to original sources
PubMed1997

A field deployable gas chromatograph/mass spectrometer for industrial hygiene applications.

To study the feasibility and efficacy of field gas chromatograph/mass spectrometers (GC/MS), the National Institute for Occupational Safety and Health (NIOSH) conducted laboratory and field testing of a commercial transportable GC/MS. That unit was reengineered and reconstructed by NIOSH as a more portable GC/MS (can be moved, set up, and operated by one person), incorporating novel weight and size-reducing vacuum technology. Further laboratory and field tests were then accomplished. This NIOSH-developed vacuum technology has proven important in reducing the size and weight of the GC/MS by up to 50%, making it much more suitable for field use. Experience has shown that for a large class of survey situations involving monitoring of components of complex mixtures of vapors and gases field use of GC/MS can be very useful.

Air Pollution↗
PubMed1992

Personnel dosimeter angular response properties and the adoption of ICRU Report 39 quantities.

A new set of quantities for applied health physics has been proposed in the International Commission on Radiation Units and Measurements publication 39 (1985), with the recommendation that they be based on the ICRU sphere phantom model. The quantities proposed for individual monitoring, which incorporate specific non-isotropic angular response properties, are designed to provide an estimate of an individual's effective dose equivalent (HE). They are the individual dose equivalent superficial (Hs(d)) and penetrating (Hp(d)). Our study of typical dosimeter-wearing practices indicated that there were no consistent locations on or angular orientations of dosimeters to the wearer's body. This demonstrated the difficulties in the practical implementation of personnel dosimeters having an angular response approximating Hp(d) for a specifically selected point on a body, rather than the traditionally assumed design goal of dosimeters utilizing an isotropic response. It also indicated the importance that dosimeters utilizing a Hp(d) response have an adequate means of mounting the dosimeter on a body to assure the required dosimeter orientation to the body under a wide range of conditions of application. Questions also remain as to how the specified ICRU sphere reference phantom (or an approximation thereof) can be used as a practical testing laboratory phantom [corrected].

Humans↗
PubMed1986

Effects of selected materials and geometries on the beta dose equivalent rate in a tissue equivalent phantom immersed in infinite clouds of 133Xe.

Most calculations of dose equivalent (D.E.) rates at 70-micron tissue depths in tissue equivalent (T.E.) phantoms from infinite clouds (radius exceeds maximum beta range in air) of 133Xe do not consider the possible effects of clothing overlays. Consequently, a series of measurements were made using a 1-mm-thick plastic scintillation detector assembly mounted in a tissue equivalent (T.E.) phantom with an overlay of 70 micron of T.E. material. This assembly was placed in an infinite cloud containing a known concentration of 133Xe. Material samples were placed at selected distances from the detector phantom, both individually and in various combinations. Pulse-height spectra resulting from beta radiations were converted to relative D.E. rates at a 70-micron tissue depth. The relative D.E. rates were reduced from values with no clothing cover by as little as 45% when placing a single thin nylon cloth 1 cm from the phantom, to 94% for a T-shirt material plus wool material plus denim placed 1/2, 1 and 3 cm, respectively, from the phantom. The results indicate that even loosely fitting clothing can have an important effect on reducing the D.E. rate. Close-fitting clothing appears to provide better protection.

Beta Particles↗
PubMed1985

An evaluation of the external radiation exposure dosimetry and calculation of maximum permissible concentration values for airborne materials containing 18F, 15O, 13N, 11C and 133Xe.

To better understand the dose equivalent (D.E.) rates produced by airborne releases of gaseous positron-emitting radionuclides under various conditions of cloud size, a study of the external radiation exposure dosimetry of these radionuclides, as well as negatron, gamma and x-ray emitting 133Xe, was undertaken. This included a calculation of the contributions to D.E. as a function of cloud radii, at tissue depths of 0.07 mm (skin), 3 mm (lens of eye) and 10 mm (whole body) from both the particulate and photon radiations emitted by these radionuclides. Estimates of maximum permissible concentration (MPC) values were also calculated based on the calculated D.E. rates and current regulations for personnel radiation protection (CFR84). Three continuous air monitors, designed for use with 133Xe, were evaluated for applications in monitoring air concentrations of the selected positron emitters. The results indicate that for a given radionuclide and for a cloud greater than a certain radius, personnel radiation dosimeters must respond acceptably to only the photon radiations emitted by the radionuclide to provide acceptable personnel dosimetry. For clouds under that radius, personnel radiation dosimeters must also respond acceptably to the positron or negatron radiations to provide acceptable personnel dosimetry. It was found that two out of the three air concentration monitors may be useful for monitoring air concentrations of the selected positron emitters.

Air Pollutants↗
PubMed1984

A study of the performance of selected instrumentation for 133Xe personnel hazard measurements in nuclear medicine laboratories.

Past studies of others, as well as the authors' experiences in measuring 133Xe concentrations in nuclear medicine laboratories, have indicated that significant and somewhat unpredictable levels of personnel exposure to 133Xe may occur in such facilities. Previous studies by the authors indicate that most personnel dosimeters do not respond to 133Xe radiations adequately for use in personnel protection applications. This indicates the need for using some types of 133Xe measuring devices for determining that 133Xe personnel exposure limits (CFR82) are not exceeded for workers in nuclear medicine laboratories. Based on these needs, selected instruments for this application were evaluated. These include four continuous 133Xe air-concentration monitors and nine survey instruments. Responses of the instruments were measured in both normal background radiation conditions and in a 133Xe atmosphere containing known concentrations of 133Xe. Based on these measurements, minimum detectable activity values were calculated for various measurement conditions. It was concluded that three of the four continuous 133Xe air-concentration monitors were suited for general applications in indicating long-term integrated personnel exposure to 133Xe. Two of the nine survey instruments evaluated were, under certain conditions, capable of measuring 133Xe concentrations under 0.015 maximum permissible concentration (MPC).

Air Pollutants↗
PubMed1982

Evaluation of 133Xe radiation exposure dosimetry for workers in nuclear medicine laboratories.

Evaluation of past studies of 133Xe dosimetry and nuclear medicine laboratory air concentrations of 133Xe indicates that significant levels of 133Xe may exist in routine operational environments of a nuclear medicine laboratory. This leads to the question of whether present health physics radiation control methods are adequate to keep occupational personnel exposures within acceptable levels. It would appear that if personnel dosimeters (film and TLD badges) respond properly to the radiation of 133Xe, normal health physics control procedures are probably adequate. If they do not respond adequately, personnel exposures may exceed recommended levels and special instrumentation or administrative procedures are called for. Therefore, the first step in studying potential problems in the subject area is to evaluate the response of a variety of personnel radiation dosimeters to 133Xe. This paper describes the methods and materials used to expose personnel dosimeters to known amounts of 133Xe radiations in an exposure chamber constructed at the BRH Nuclear Medicine Laboratory. Also presented are calculated values for Dose Equivalents (D.E.) in a phantom from external radiation resulting from immersion in clouds having a constant concentration of 133Xe but varying cloud radii. This implies the relative importance of the beta and the X + gamma radiation responses of the personnel dosimeters under various exposure conditions. Results of this study indicate that none of the dosimeter systems evaluated provide adequate performance for use as a primary indicator of the D.E. resulting from 133Xe radiations for a worker in a nuclear medicine laboratory, and that personnel dosimetry considerations in 133Xe-containing atmospheres are very dependent on the radii of the 133Xe clouds.

Environmental Exposure↗
PubMed1982

Development of a correction factor for Xe-133 vials for use with a dose calibrator.

Manufacturers of dose calibrators who gave calibration settings for various radionuclides sometimes do not specify the type of radionuclide container the calibration is for. The container, moreover, may not be of the same type as those a user might purchase. When these factors are not considered, the activity administered to the patient may be significantly different from that intended. An experiment is described in which calibration factors are determined for measurement of Xe-133 activity in vials in a dose calibrator. This was accomplished by transferring the Xe-133 from the commercial vials to standard NBS calibration ampuls. Based on ten such transfers, the resulting correction factor for the dose calibrator was 1.22.

Drug Labeling↗
PubMed1979

The low-temperature scintillation properties of bismuth germanate and its application to high-energy gamma radiation imaging devices.

Bismuth germanate is a scintillation material with very high z, and high density (7.13 g/cm3). It is a rugged, nonhygroscopic, crystalline material with room-temperature scintillation properties described by previous investigators as having a light yield approximately 8% of that of NaI(Tl), emission peak at approximately 480 nm, decay constant of 0.3 microsec, and energy resolution congruent to 15% (FWHM) for Cs-137 gamma radiations. These properties make it an excellent candidate for applications involving the detection of high-energy gamma photons and positron annihilation radiation, particularly when good spatial resolution is desired. At room temperature, however, the application of this material is somewhat limited by low light output and poor energy resolution. This paper presents new data on the scintillation properties of bismuth germanate as a function of temperature from -- 196 degrees C to j0 degrees C. Low-temperature use of the material is shown to greatly improve its light yield and energy resolution. The implications of this work to the design of imaging devices for high-energy radiation in health physics and nuclear medicine are discussed.

Bismuth↗
PubMed1978

An evaluation of ultraviolet radiation personnel hazards from selected 400-watt high intensity discharge lamps.

A study of selected mercury and multi-vapor lamps, commonly used for working environment illumination, was underta ken to evaluate the scope of the ultraviolet personnel hazards one may expect under various operating conditions of the lamps. Spectral irradiance measurements were made for operating conditions with and without reflector-type luminaires, glass covers on luminaries and outer glass bulbs on the lamps.

Environmental Exposure↗
PubMed1976

A portable spectroradiometer for use at visible and ultraviolet wavelengths.

To date there has been a lack of a suitable survey instrument for evaluating occupational hazards of ultra violet radiations. A portable optical spectroradiometer has been developed consisting of a miniature tandem grating monochromator with a photomultiplier detector. This instrument appears to satisfy operational requirements for an ultraviolet hazard survey meter.

Environmental Exposure↗
PubMedDate not supplied

Design of a target system for producing clinically useful quantities of oxygen-15 using an electron linear accelerator.

The nuclear medicine uses of short-lived positron emitters, such as 15O and 11C, rely primarily on the cyclotron production of these radionuclides. This paper presents an alternate approach to production of 15O by the use of photonuclear reactions on 16O, using bremsstrahlung radiation produced by an electron linear accelerator. Methods are described which produce useable quantities of relatively high specific activity 15O (25.1 mCi/4 min at 27.9 Ci/g), using a reboiling H2O target, with an electron linear accelerator having an electron beam energy of 26 MeV and a beam current of 100 microamperemeter. Results of this target system are compared to those of a target system developed recently by other investigators.

Methods↗
PubMedDate not supplied

Measurement of activity yields for 12C(gamma, n)11C, 14N(gamma, n)13N, and 16O(gamma, n)15O reactions as a function of electron beam energy and angle from the electron beam using thick target produced bremsstrahlung.

The calculation of activity yields from practical photonuclear target systems designed to produce short-lived positron emitting radionuclides for nuclear medicine purposes requires certain basic information. These include a knowledge of the photon source (bremsstrahlung energy spectrum and intensity as a function of angle from the electron beam) and the gamma, n activation cross section of the secondary target element. A lack of adequate information concerning these parameters motivated the present study in which activity yields for the reactions 12C(gamma, n)11C, 14N(gamma, n)13N, and 16O(gamma, n)15O were measured as a function of energy of and angle from the electron beam between 16 and 30 MeV and 0 degree and 30.5 degrees, respectively. The data indicate highly complex relationships between the activity yield and the experimental variables. Also indicated are possible applications of the data to indicate the energy of an electron beam producing a given bremsstrahlung field in which activation measurements are made.

Carbon Radioisotopes↗
PubMedDate not supplied

Photonuclear target systems for producing clinically useful quantities of 11C using an electron linear accelerator.

Described in this paper are what we believe to be the first practical photonuclear target systems for production of 11C containing CO and CO2 using bremsstrahlung produced from an electron linear accelerator similar to certain radiotherapy accelerators. This is a continuation of work reported earlier concerning a similar target system presently being used for production of 15O-O2. The 11C producing systems utilized liquid carbon dioxide, liquid cyclohexane, and liquid glacial acetic acid target materials. The carbon dioxide and glacial acetic acid target materials produced principally a 11C-CO product material. The cyclohexane target material produced a 11C-hydrocarbon product which was then oxidized to CO2. Target activity yields for these systems, normalized to a 20-cm-long by 10-cm-diam target chamber irradiated in a bremsstrahlung field produced by a 26-MeV, 100-microA electron beam, were 1.9 X 10(8) Bq (5 mCi) at 7.4 X 10(8) Bq g-1 (20 mCi g-1) for carbon dioxide, 1.4 X 10(8) Bq (3.8 mCi) at 3.7 X 10(10) Bq g-1 (1 Ci g-1) for cyclohexane, and 7.4 X 10(8) Bq (20 mCi) at 3.7 X 10(10) Bq g-1 (1 Ci g-1) for glacial acetic acid.

Acetates↗
PubMedDate not supplied

A system for quantitatively assessing certain performance parameters of gamma camera systems from reflective print and film transparency final images.

Past efforts at routine evaluation of gamma camera systems performance, using final product images, primarily resulted in qualitative assessments. This paper describes a system for quantitatively determining certain performance parameters of gamma camera systems using paper-backed print and transparent film test images of the same type used for viewing by the nuclear medicine physician. By use of appropriate transmission and line source phantoms, the gamma camera system's spatial resolution, distortion, and flood field uniformity as a function of position in the image field, are determined using a semiautomated image scanning and data reduction system. This system consists of a high-resolution scanning microdensitometer/reflectometer, interfaced to a computer, along with necessary programs to locate bar and line grid intersection points in the image. Also included are algorithms for calculating the various image parameters desired. This system may provide an analytical method for quantitatively assessing certain performance parameters of gamma camera systems, using the final-product images from the cameras.

Densitometry↗