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Biomedical subjects

S Reichmann

Publications and source records attributed to S Reichmann.

At least 19 recordsLinked to original sources
PubMed1992

Cerebral symptoms after whiplash injury of the neck: a prospective clinical and neuropsychological study of whiplash injury.

Twenty one unselected patients with an acute whiplash injury of the neck had neurological and neuropsychological assessment, cervical x rays, EEG, BAEP, MRI, and an otoneurological examination within two weeks of the injury. Subjectively, 13 patients reported concentration deficits, 18 reported sleep disturbances, 9 had symptoms of depression, and 7 female patients told of menstrual irregularities. Neuropsychological examination revealed significantly lower performance in tests related to attention and concentration compared to sex, age and educational matched control subjects. Otoneurological examination showed abnormalities in 9 of 17 whiplash subjects. EEG showed questionable changes in 8 of 18 recordings. MRI and BAEP were normal in all patients. Repeat neuropsychological testing in 15 patients at three months showed that attention deficits had improved but were still shown in 12 of 14 and the concentration deficits in 8 of 13 patients. At one year all patients had returned to work, 16 to full and 5 to part time employment. In 4, cognitive dysfunction remained the only significant problem. These findings are discussed as being compatible with possible damage to basal frontal and upper brain stem structures after whiplash injury of the neck.

Adolescent↗
PubMed1979

Influence of radiation dose on image quality.

When the speed of a recording medium is doubled the background quantum mottle is increased by a factor square root 2. However, the signal/noise ratio is changed not in proportion to the square root of the exposure, but in a linear fashion, i.e. by a factor 2. The change in the depiction of objects with a very high attenuation difference in relation to its surroundings appears not to be linear, but proportional to the square root of the exposure. Such objects (metal wire meshes, lead bar grids) should thus be avoided in routine evaluation of image quality since they give incomplete information as to image impairment when high-speed recording media are used.

Angiography↗
PubMed1979

Visual evaluation of microscopic mottle.

According to Rose the resolution of an imaging system is under certain conditions limited by noise rather than by the finite geometric response as expressed by the modulation transfer function. In order to investigate whether this applies to clinical radiography as well, a technique for magnification of roentgen films has been devised, making possible visual evaluation of microscopic noise.

Methods↗
PubMed1979

Relevance of radiographic resolution capacity.

Resolution capacity is traditionally evaluated by radiography of metal objects (lead bar grids or fine slits). These objects yield high image contrast. Resolution, then, is limited by the sideways spread of information as expressed by the MTF. However, biologic objects of fine dimensions give rise to much less image contrast than the test objects of metal. Since the amplitude of the signals thus becomes reduced the signal/noise ratio in fact limits resolution capacity much more effectively than does the sideways spread of information. Thus, the MTF expresses a property of the radiographic system which appears only rarely to affect the information capacity of clinical radiographic images.

Contrast Media↗
PubMed1979

Influence of microscopic mottle on the definition of small image details.

By a special technique of enlarging films, a microscopic mottle caused by quantum fluctuations was demonstrated. It was found to affect depiction of small details in such a way as to suggest that it would be of importance for determining resolution capacity, especially in high-speed radiography. Thus, the modulation transfer function appears not to be the only factor determining radiographic resolution. The resolution of high-speed screens may be improved if the film speed is reduced, which leads to a diminished microscopic mottle.

Photography↗
PubMed1979

Optimised tomography for clinical use.

A technique elaborated by the present authors (1974) for the establishment of optimum tomographic movements was applied to ear tomography in order to design a movement that is not too complex, but yielding good tomographic depiction. Such a movement was found to consist of a spiral of 5 revolutions. Modern engineering appears to allow such complex movements to be carried out with satisfactory stability within a reasonable exposure time.

Ear, Inner↗
PubMed1979

Tomographic localization of motion axes.

Localization of motion axes within joints and junctures in living humans has been carried out by means of roentgen stereophotogrammetry. Another technique is presented here, in which the localization of the axis is carried out by means of tomography. The field of application for this technique has been examined in a series of phantom experiments. It may be employed in certain situations where roentgen stereophotogrammetry is not useful. No other equipment is needed than a pluridirectional tomograph and conventional dark-room facilities.

Arthrography↗
PubMed1979

Choice of screens in high-speed angiography.

In phantom experiments a number of intensifying screens were tested as regards their usefulness for angiography. Film speed was adjusted so as to make possible a constant radiographic exposure despite screen speeds varying by a factor of 3. Thus, screen unsharpness varied considerably. However, it was of no practical importance as long as the radiographic exposure was kept constant. This observation indicates that the modulation transfer function is of limited value in differentiating between screens for high-speed angiography. Likewise, film contrast was of little significance for image quality, as compared with radiographic exposure to the intensifying screens.

Angiography↗
PubMed1979

Quantity of tomographic blurring.

A spiral tomographic movement gives rise to a lower quantity of blurring than does a circular movement with the same tomographic angle since in the former the focus comes nearer to the central point. It has been demonstrated that the transfer function may be used to express the quantity of blurring for different tomographic movements. For the sake of convenience the blurring quantity for every type of spiral movement may be expressed in terms of the tomographic angle of a circular movement giving rise to the same transfer function.

Technology, Radiologic↗
PubMed1978

Medichrome film as an alternative to silver-free recording systems.

A shortage of silver is forcing film manufacturers to lower the silver content of radiographic films. No further lowering seems possible without film quality being adversely affected. Various ways to solve the silver problem in the future are discussed and colour radiography is regarded as one solution since it makes possible a high degree of immediate recovery of silver. The feasibility and proper use of the only colour film available, Medichrome, is discussed. Suitable screens in order to compensate for the low sensitivity of the film without loss of image quality and a strong light source containing a monochromatic sodium lamp for inspection of dense areas are recommended.

Radiography↗
PubMed1978

Testing of roentgen film quality.

Evaluation of film quality is often based upon the film's characteristic curve. A practical test method implying radiography of sandpaper sheets has been devised, yielding crucial information about the quality, which cannot be derived from the characteristic curve. Since this test appears to give more valid information about film quality than conventional sensitometry, it is suggested that the test procedure should be standardised and used by the manufacturers.

Absorptiometry, Photon↗
PubMed1977

High-density failure of radiographic films.

The recording of weak signals of high spatial frequency emanating from intensifying screens has been analysed in different films at varying densities. Even if the gamma value is kept constant over a wide range of densities, the recording of these signals is impaired at high densities above a certain optimum density, coinciding with the lower part of the straight part of the characteristic curve. The recording of these signals appears to be related to the number of silver halide grains per unit area available for signal recording rather than to the contrast as represented by the gamma value. When the density of the image is increased more grains are precipitated in creating the background density, leaving a smaller number of grains unaffected for the signals added on top of the background. If the signal frequency is high and the amplitude is low the remaining grains appear to become too few and too scattered for a proper recording, so that the signal cannot appear in the image. Since this occurs at densities where the film is not usually considered to be overexposed the phenomenon is called high-density failure. Different films may display great differences in high-density failure even if the sensitivity is the same.

Technology, Radiologic↗
PubMed1977

Xerographic tomography.

Tomographic depiction using Xerox plates was compared with that of screen film tomography. The Xerox plates entail much higher demands as to the quality of tomographic blurring than screen film combinations. Circular or hypocycloid movements give rise to errors of depiction which are more disturbing in xerographic tomography due to the fact that the screen film combination has such properties as to be unable to record certain spurious signals present in the radiation relief, which appear in the higher-precision recording of the Xerox plates. This indicates that these plates are to be preferred if only the spurious signals can be eliminated. Suitable tomographic movements are described. To counteract the high radiation doses in xerotomography, it is suggested that specially constructed cassettes for simultaneous multisection tomography should be used.

Ear↗
PubMed1977

The biomechanical influence of traction on the cervical spine.

The effects exerted on the cervical spine by a traction of 150 N was studied by means of an improved radiographic technique. The technique is presented together with results from a study including fifteen test subjects with and without clinical symptoms of neck pain. In a minority of discs a widening not exceeding 1 mm was seen. This widening was not correlated to presence of roentgen signs indicating degenerative disease of the disc nor to clinical symptomatology.

Adult↗
PubMed1976

Adverse effects of stationary grids.

By means of simple tests, the mechanisms of image impairment due to stationary grids were demonstrated. Several contributing factors were found. The fact that the grid strips are not clearly visible in the film does not indicate that image quality is not lowered by the grid. To a certain degree it demonstrates that the image quality is so low that not even the grid lines are perceptible.

Evaluation Studies as Topic↗
PubMed1975

Intensifying screens in soft tissue radiography.

Certain screen-film combinations were tested in the low voltage range (26 to 40 kV, tungsten target) and compared with an optimal non-screen industrial film. The dose reduction was of no consequence as compared with the loss in image quality. Some physical properties of the screens giving rise to the failure are discussed.

Evaluation Studies as Topic↗
PubMed1975

Filtration in soft tissue radiography.

The influence of K-edge filters in combination with tungsten target tubes has been analysed in the low voltage range. It appears that these filters do not offer any advantages with this target material. Al-filtration, applicable to different types of soft tissue radiography of joints is discussed.

Aluminum↗