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Biomedical subjects

W R Hendee

Publications and source records attributed to W R Hendee.

At least 19 recordsLinked to original sources
PubMed1991

Personal and public perceptions of radiation risks.

Risks often are accompanied by benefits, which are not attainable without incurring the risks. When a person voluntarily decides to take a risk, he or she assumes responsibility for the outcome, whether beneficial or adverse. The converse concerning involuntary risks is also true, with the result that many people oppose involuntary risks with their threat of adverse outcomes. Medical exposure to radiation can be perceived as both an involuntary and voluntary risk. In American culture, the entertainment and news media have contributed greatly to the public's abhorrence of radiation, radioactivity, and nuclear energy. Because people respond emotionally rather than intellectually to risk information, the risks of radiation exposure are best communicated by someone who is knowledgeable, is recognized as a health expert, is trustworthy, and has no conflict of interest but a stake in the community, such as a community physician. Such a spokesperson must respond first to perceptions of risks and underlying emotions, since use of only facts often fails to counteract fears. With trust established, a rational discussion of risks and benefits can begin.

Attitude↗
PubMed1978

Transport phenomena in laminar flow of blood.

Recently it has been shown experimentally that transport of heat and gas (specifically oxygen and helium) are augmented in the laminar flow of aqueous suspensions of polystyrene spheres 50 and 150 micrometer in diameter. In this report, data on heat and gas transport are correlated. Application of this correlation to flowing blood leads to the following conclucions. There is no significant augmentation of oxygen and heat transport in flowing blood even at shear rates much higher than physiological shear rates; an observation which is in accord with the experimental results. The augmentation of the diffusion coefficient of plasma proteins in flowing blood, though not very high, appears to be measurable. Of the total measured augmentation of about 6000--30 000% in platelet diffusivity in flowing blood, quoted from the literature, about 500% is attributable from this correlation to fluid mechanical forces, and the balance is hypothetically attributed to other forces (electrical or biochemical) present in blood.

Biological Transport↗
PubMed1978

Thermal design of a heat exchanger for heating or cooling blood.

Experimental data, and their correlation with predictions from theory, are presented for the thermal design of a countercurrent heat exchanger for heating or cooling blood. The thermal design considers the influence on the Nusselt number of blood and the heat exchanger effectiveness of variables such as the blood flow rate, tube diameter and length, and the thermal properties of blood. The data presented are compared with data from the literature and with predictions from theory. Insofar as the design of a blood heat exchanger is concerned, flowing blood can be considered a single-phase fluid. Results of the thermal design analysis are applicable to attempts to produce and control blood hyperthermia for applications such as the perfusion of tumours of the extremities, and to efforts to induce hypothermia during open-heart surgery.

Blood↗
PubMed1978

Optimization of xeroradiographic exposures.

Xeroradiographs were exposed over a range of mAs and kVp in the mammographic energy range. At each kVp, the technique yielding the widest halo also produced the greatest detectability of small aluminum specks in mammographic phantoms. As the kVp increased, the maximum halo width and number of visible specks decreased. At all kVps, the techniques yielding the widest halo furnished almost constant energy deposition in the selenium plate. This constant plate dose was correlated to patient exposure at the entrance of the breast, and the relationships between patient entrance exposure, kVp, and minumum detectable speck size were determined.

Female↗
PubMed1978

A variable aperture fluoroscopic unit for reduced patient exposure.

A real time fluoroscopic imaging system which provides capability for reduced patient exposure by as much as a factor of five has been developed. Modifications to the system include the incorporation of a variable aperture iris between the image intensifier output phosphor and television camera and the use of the video signal as the feedback element in the fluoroscopic automatic exposure rate control system. Quantitative and qualitative performance of the system is described.

Fluoroscopy↗
PubMed1977

Radiation exposure in radiographic examinations of the newborn.

Radiation exposure of the newborn during routine chest and abdominal radiographic examinations has been determined. The exposure has been measured at sites representing the entrance and exit chest, entrance, midline, and exit abdomen, the gonads, and the thyroid. Results of these measurements are reported as a function of kVp and in terms of mR received at the anatomical site per mR output of the generator at 24 in. (61 cm). This reporting procedure facilitates application of the results to exposure estimates under similar conditions at other institutions.

Humans↗
PubMed1977

Effects of motion on the radiological image.

A method to study the loss of resolution of radiological images caused by patient motion is presented. Optical transfer functions (OTF) are computed for motion with uniform velocity and with simple harmonic oscillation. The line spread function (LSF) of a pattern of motion can be generated from the image of a long, narrow moving slit. Once the LSF is known the OTF of the motion can be obtained by Fourier transform.

Mathematics↗
PubMed1976

Performance evaluation of phototimers.

Phototimers detect x rays impinging on or emerging from an x-ray film cassette and terminate the exposure after a predetermined amount of radiation has been received by the film. A phototimer must provide reproducible film exposures over a wide range of target-to-film distances, patient thicknesses, and technique variables. A method is needed which verifies that the phototimer is functioning properly and identifies exposure techniques and practices which are compatible with its use. Several techniques are presented for evaluating phototimer performance, and data accumulated during application of these techniques to the use of three spot-film phototimers are presented.

Technology, Radiologic↗
PubMed1976

Performance specifications for diagnostic x-ray equipment.

The specification of performance characteristics for diagnostic x-ray equipment involves an interplay between purchaser and supplier which often results in inadequate understanding of imaging requirements by the supplier, and unfulfilled expectations by the purchaser. A statement of performance specifications has been prepared and accompanies requests for bids distributed to suppliers. The statement is described in its general form; modifications bay be needed to adapt it to a specific radiographic system.

Humans↗
PubMed1976

An evaluation of rare earth screen/film combinations.

The physical and imaging characteristics of a number of commercially available rare earth screen/film combinations were evaluated and compared to those of conventional calcium tungstate/X-Omat RP-14 systems. All systems were evaluated for base-plus-fog density, relative speed, resolution, noise, and overall performance. The results indicate that despite certain limitations, rare earth screen/film combinations offer significant advantages for imaging.

Calcium↗