Biomedical subjects

K Rossmann

Publications and source records attributed to K Rossmann.

At least 19 recordsLinked to original sources

PubMed1986

Energy cost determination using a portable accelerometer.

The purpose of this study was to determine the physical activity of physical therapists during clinical practice. Nineteen physical therapists from three clinical facilities wore portable accelerometers on their waist belts or chest pockets for the duration of their work shifts. The subjects repeated the experiment on the second day. The accelerometer readings (in arbitrary units) were converted to oxygen consumption VO2 and energy expenditure (kcal) values using previously derived regression equations. The PTs worked an average of 7.9 hours during each shift. The total energy expended during the work shift ranged from 933.6 to 1,689.6 kcal. A correlation coefficient of .91 was found between the accelerometer readings (count X hr-1) recorded on day 1 and day 2 of the study. The analysis of variance revealed that the PTs in the three clinical facilities were not significantly different in age, height, and work-shift duration, but were significantly different (p less than .05) in weight, mean accelerometer readings, and estimated VO2 (L X min-1). When the VO2 was expressed in mL X kg-1 X min-1, no significant difference was found between the PTs in the three clinical facilities. The implications and limitations of the findings are discussed.

Adult↗

PubMed1982

Ointments for the protection against organophosphate poisoning.

Ointments for the protection against poisoning of the skin by highly toxic organophosphates or organophosphate insecticides were prepared and examined for their protective effect both on guinea-pig skin in vitro and on guinea-pigs in vivo. The results of these investigations were as follows: 1. The prophylactic application of the ointments yields 20 fold reduction of the permeation rate of the toxic organophosphate compared with unprotected skin. 2. The ointments on a polyethyleneglycol basis show their best protective effect if they contain both a base and an active substance. 3. Maximum possible protection can be achieved by applying a thick layer of ointment which should be mechanically removed (by wiping with a damp cellulose tissue) from the contamination site within 30 min.

Animals↗

PubMed1977

Application of longitudinal magnification effect to magnification stereoscopic angiography: a new method of cerebral angiography.

A new method of stereoscopic cerebral angiography has been developed which employs 2X radiographic magnification. In order to obtain the same depth perception in the object as with conventional contact stereoscopic angiography, one can made the x-ray exposures at two focal spot positions which are separated by only 1 inch (2.5 cm), whereas the contact technique requires a separation of 4 inches (10 cm). The smaller distance is possible because, with 2X magnification, the transverse detail in the object is magnified by a factor of two, but the longitudinal detail, which is related to the stereo effect, is magnified by a factor of four, due to the longitudinal magnification effect. The small focal spot separation results in advantages such as improved stereoscopic image detail, better image quality, and low radiation exposure to the patient.

Cerebral Angiography↗

PubMed1977

Screen/film system speed: its dependence on x-ray energy.

Dependence of the speed of various screen/film systems on x-ray energy was studied using the nearly monoenergetic x rays emitted by a filtered fluorescent source. The results show that response depends on screen phosphor composition and thickness. Barium and rare earth screens having K absorption energies lower than that of calcium tungstate are relatively more sensitive to x rays in the 40-70-keV region.

Technology, Radiologic↗

PubMed1976

Comparison of image quality obtained with optical and radiographic magnification techniques in fine-detail skeletal radiography: effect of object thickness.

High-resolution radiography may be done using either optical or radiographic magnification. In the former technique, industrial Type M film was used without screens and the image was viewed with 4-10X optical magnification. In the latter technique, RP film was used with Detail screens and 4X geometric magnification together with a microfocus x-ray tube having a nominal focal spot size of 50 mum. The imaging properties of both techniques were evaluated by means of H & D curves, modulation transfer functions, and Wiener spectra. It was found that for thin objects such as the hand, optical magnification provides better bone images than radiographic magnification; whereas for thicker parts such as the knee, radiographic magnification is superior.

Bone and Bones↗

PubMed1976

The effect of x-ray spectra from molybdenum and tungsten target tubes on image quality in mammography.

The measured x-ray spectra from a molybdenum anode Senographe mammography unit and a tungsten anode unit were used to calculate the x-ray energy spectra transmitted through various thicknesses of fat and water (breast-equivalent materials). The dependence of subject contrast and patient exposure on (a) x-ray spectra, (b) attenuation properties of two breast-equivalent materials, and (c) thickness of breast-equivalent material was predicted. Radiographs of resected breast tissue confirmed these predictions and demonstrated the general relative effects of x-ray beam quality on image contrast in mammography.

Adipose Tissue↗

PubMed1975

Effect of focal spot distribution on blood vessel imaging in magnification radiography.

From a computer simulation study of blood vessel imaging with uniform, triangular, gaussian, and twin gaussian line spread functions (LSF) corresponding to various focal spot distributions, it is found that vessel images magnified less than 6 times are not strongly dependent upon the focal spot distributions when the size of the focal spot is equal to or smaller than the vessel diameter. When the focal spot is larger than the vessel, image distributions vary appreciably with focal spot distributions, except at low magnification. It is concluded that, in many practical cases, the focal spot distribution does not seriously affect magnified image distributions of blood vessels.

Angiography↗

PubMed1975

Longitudinal magnification in radiologic images of thick objects: a new concept in magnification radiography.

New concepts which are useful for evaluating image resolution and distortion in magnification radiography are introduced. It is shown theoretically and experimentally that "longitudinal magnification" defined as the ratio of the magnified image size to the conventional image size for objects located in a plane perpendicular to the film, is given approximately by the square of the conventional magnification. Resolution in the radiographically magnified image of such objects is much higher than that obtained by optical magnification. This is confirmed experimentally by radiographs of square-wave test objects. The related image distortion is also discussed.

Mathematics↗

PubMed1974