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Biomedical subjects

H E Johns

Publications and source records attributed to H E Johns.

At least 19 recordsLinked to original sources
PubMed1995

How consumers view chiropractic advertising.

Chiropractic, as a medical profession, is finally receiving acceptance from the American Medical Association (AMA) and other medical groups. However, what do consumers think about chiropractors and how do they respond to the advertising efforts of chiropractors? This paper presents the findings of a survey concerning consumers' opinions of advertising by chiropractors. Although the opinions of the respondents were mixed, an analysis of the results of the survey suggests important implications for chiropractors and other medical practitioners who wish to use advertising media in marketing their services.

Advertising↗
PubMed1989

How consumers view physician advertising.

In this study, it was found that consumers generally favor advertising by physicians. They felt that newspaper and professional magazines were more appropriate media for such advertising than television, radio, billboards, telephones, direct mail, and popular magazines. Finally, most consumers have not seen physicians advertise, but of those who have, most have noticed such advertising in a newspaper.

Advertising↗
PubMed1988

How consumers view hospital advertising.

The purposes of this study were to determine: (a) consumers' attitudes toward advertising by hospitals; (b) which media consumers feel are appropriate for hospital advertising; and (c) whether consumers are seeing hospital advertisements, and if so, through which media. It was found that consumers indeed have a favorable attitude toward hospitals that advertise. It was also found that consumers feel that most media are appropriate for hospital advertising. Finally, it was found that most consumers have seen hospitals advertise their services, especially on television and radio and in the newspaper.

Advertising↗
PubMed1984

Measurement of the effective dose equivalent in a nuclear reactor environment with a personal thermoluminescent dosimeter.

A study was performed on the measurement of the effective dose equivalent (EDE) with a personal thermoluminescent dosimeter. A Rando phantom with dosimeters inserted at the sites of the tissues specified by ICRP Publication 26 (ICRP77) was exposed at selected locations inside nuclear power stations. The effective dose equivalent was calculated and compared to the personal dosimeter response worn at the normal chest and waist locations. It was found that the EDE could be adequately measured and that the average rem/R conversion factor varied between 0.79 and 0.87, depending on the wearing position and sex of the worker.

Female↗
PubMed1980

A technique for the treatment of large irregular fields.

Each method of producing irregular shaped fields has its own particular advantage. This report describes one technique of irregular field production with minimal handling of the shielding material, tapered shielding to provide the greatest accuracy in the field shape, and rapid achievement of patient setup. The reproducibility of these fields is considered.

Humans↗
PubMed1979

Variations in x-ray exposures to patients.

X-ray exposures to patients were measured in 30 rooms in Toronto hospitals. For a given procedure, the total exposure for a satisfactory examination differed from one room to another by as much as a factor of 30, skin exposures reaching 90 R and more for barium enemas and barium meals. The factors primarily responsible for these large differences in exposure were fluoroscopic exposure rate (0.65-12 R/min) and time 1.5-12 min), kVp and filtration (8:1), choice of screen-film combination (6:1) and attenuation of table tops and phototimers (4:1). The increase by a factor of 5 in exposure of pelvic organs, when using beams directed AP instead of PA, requires that remote-controlled GI machines be used cautiously, particularly on women of childbearing age. It is also important that these machines have tables with low attenuation. The use in some rooms of minimal fluoroscopic exposure rates and 70 mm fluorography at total exposures of less than 5 R shows that radiographic examinations can be made virtually "safe" with modern, properly adjusted equipment.

Barium Sulfate↗
PubMed1978

Edge contrast in ionography.

The effect of Mylar foil thickness on the appearance of ionography images has been investigated. Approximate expressions for the depletion width of strips and halfplanes of charge are given with supporting experimental measurements. In microdensitometer traces of charged strips and halfplanes the density is shown to be proportional to the vertical field profile of the charge pattern near the Mylar. This work suggests a simple means of altering edge contrast for ionography by using different thicknesses of Mylar. Ionography images of a hand phantom illustrate this effect.

Radiographic Image Enhancement↗
PubMed1976

New methods of imaging in diagnostic radiology Sylvanus Thompson Memorial Lecture.

A brief history of the recent developments in computer-assisted tomography (CAT) is presented. The development of whole-body scanners from the basic brain scanner, the trend towards higher-speed scanners using multiple detectors in a fan-type geometry, and some of the unsolved problems related to CAT scanners are discussed, as well as the potential use of whole-body scanning in radiotherapy treatment planning and in radiobiology. A review of recent developments in electrostatic imaging is presented and a new method of imaging called ionography is described in detail. It is shown how a single exposure can be used to produce a number of copies, each with a different amount of edge contrast, under the control of the radiologist. Further, it is shown how this can be done using a closed system so that the ionography chamber never needs to be opened. Some of the recent commercial developments in this field are described. It is suggested that in the future radiology departments may be replaced by departments of imaging, which will include all ways of obtaining diagnostic information and where such a department would be problem oriented rather than technique oriented. The need for basic scientific support by a medical physics and engineering group in such a department is emphasized.

Electrons↗
PubMed1975

New methods of imaging in diagnostic radiology.

The basic ideas of electrostatic imaging with special reference to ionography are reviewed. The concept of edge contrast is explained in terms of calculated powder particle trajectories and methods for controlling edge contrast are presented. Also, methods for reading a foil from outside the ionography chamber using the electric field extending through the foil are described. An example of an image taken with liquid in the chamber (liquid lonography) is presented, and the possible extension of liquid ionography to nuclear medicine is discussed.

Absorptiometry, Photon↗
PubMed1975

X-ray depth doses from linear accelerators in the energy range from 10 to 32 Mev.

The depth dose characteristics of the x-ray beam from a linear accelerator have been studied in the electron energy range from 10 to 32 MeV for various target and flattening filter combinations. At all energies the most penetrating x-ray beam is obtained with a low atomic number flattening filter. At energies below 15 MeV a high atomic number target should be used, while at energies above 15 MeV a low atomic number target should be employed to get the best depth dose distribution. The optimum target thickness is approximately equal to the mean range of electrons in the target material. The study of some physical parameters such as depth dose, average dose, and integral dose, suggests that the optimum energy for linear accelerators used in the x-ray mode is about 25 MeV.

Aluminum↗