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G Hagemann

Publications and source records attributed to G Hagemann.

At least 73 records · Page 4Linked to original sources
PubMed1985

[Image quality assurance in x-ray diagnostic units. Information on DIN 6868 standard series].

The Working Group for Standardisation justifies and comments on the establishment of a standard series for image quality assurance in X-ray diagnostic services (DIN 6868). In order to promote compliance with these standards, the users are given some background information on the structure of the standard series and on the recommended procedures to be followed. The definitions for the various hierarchically arranged tests, such as constancy test, status test, acceptance test as well as a definition for the term "base-line image quality" are explained.

Germany, West↗
PubMed1980

[Quality control in X-ray diagnostic equipment with automatic exposure using a newly-developed test phantom. I. Tube voltage and exposure time].

Results are reported on quality tests with 42 automatically exposed X-ray films of a phantom in respect of the seven parameters of tube voltage, time of exposure, surface dose, resolution close to and distant to film, optical density of dominant, film contrast and size of focus. In the first part of the study reported here, the electronically measured nominal value deviations of tube voltage and the distribution of exposure times are graphically represented and partly described quantitatively via their averages and standard deviations.

Mathematics↗
PubMed1980

[Quality control of Roentgen equipment with automatic exposure using a newly developed test phantom. Part II: surface dose, image parameters and quality number (author's transl)].

The article reproduces further results of quality control tests conducted with 42 automatically exposed roentgenographs of a test phantom, for the parameters surface dose (Do), film-distant (AF) and film-proximal (AN) resolution, optical density of dominant (SDom), film contrast (KF) and size of focus. By means of definition of the quality number z = AN x AF/log10 x Do, it is possible to state the sequence of qualitatively different X-ray films and to plot this against log10 t to take organ movements into consideration, thus supplying a simple criterion of the quality of Roentgen equipment. Good equipment will yield values of z/log10 t = 3, whereas medium-quality and insufficiently equipped apparatus will yield values around 2 or 1, respectively, or even below this figure. If the values are too low, analysis of all data obtained with the test phantom will supply indications with regard to the possible causes. Of the 42 X-ray films tested in this study, the z/log10 t values were above 2 in 15 cases, and below 2 in the same number of cases. Variations in the size of focus, optical density of dominant and contrast, are shown in the diagrams and described quantitatively by their average values anad standard errors.

Models, Structural↗
PubMed1978

[New intensifying screens in clinical radiology III: Screen-film combinations in mammography (author's transl)].

An industrial film was compared with four commercially available screen-film combinations with respect to dose, definition and signal to noise ratio. The demanded minimum resolving power requires definition of an object of 100 micrometer size. However, the defined minimum object sizes are approx. 180 micrometer with close-distance projection and approx. 240 micrometer with greater distance. In this study, therefore, the signal to noise ratios were measured at defined object sizes of 5 lp/mm and 2 lp/mm. The screen-film combinations have approximately the same values as the industrial film for a size of 250 micrometer (2 lp/mm) or are definitely higher. The signal to noise ratio of the Alpha M combination is superior by 50%, although the sensitivity of the combination is 4 to 6 times greater. The signal to noise ratio of the MinR system in 25% higher than that of the industrial film, the required dose being lower by a factor of 8. This results in skin doses of 0.7 rads instead of 6 rads with tissue layers of 4.8 cm thickness.

Female↗
PubMed1977

[The effect of bleomycin, ICRF 159 and of simultaneous X-ray application on CHO-fibroblasts].

The cell damage of the cytostatics Bleomycin and ICRF 159 were studied experimentally by the use of the following parameters: colony survival, colony-size-spectrometry and multiplicity of CHO-Fibroblasts. Series of increasing drug concentrations and simultaneous irradiation with 200 rds were measured. In the above mentioned tests an additive and no potentiating effect of damage by the cytostatics in combination with irradiation of 200 rds was found. Compared with Bleomycin, ICRF 159 showed a higher degree of damage to CHO-Fibroblasts.

Animals↗
PubMed1976

[Clinical and hemodynamic aspects of myocardial diseases (author's transl)].

Definition, arrangement into primary and secondary forms and classification of myocardial diseases are used irregularly in the literature. The great variety of clinical and hemodynamic parameters are shown with reference to our own patients and an attempt is made to arrange them in individual types. Followup examinations show that signs of congestive failure, heart size and other clinical and hemodynamic parameters may be considerably altered. For this reason it is proposed to describe myocardial diseases accoridng to clinical and hemodynamic parameters in order to obtain a closer insight into the pathomechanism of these diseases.

Cardiomegaly↗
PubMed1976

[New intensifying screens in clinical radiology. Paper I-Experimental investigations (author's transl)].

The degree of intensification and resolution was compared using rare-earth-screens and conventional calcium tungstate screens. -In order to approximate usual phantom (DIN 6, 815) was equipped with a lead grid at a depth of 6 cm. Nine screen-film combinations were exposed at 70 to 80 kv., using a 12-pulse generator and Bucky grid till blackening of S = 1 was obtained. -Resolution depends substantially on the inherent noise of the system and improves from 0.6 Lp/mm. for the most sensitive combinations (intensitification factor 8.0) to 1.15 Lp/mm (intensification factor 1.7). Compared with the standard combination with a resolution of about 0.9 Lp/mm., dose was reduced by more than 40% with an increase in resolution of 45% (combination 3M-Trimax A4/XD).

Dose-Response Relationship, Radiation↗
PubMed1976

[New intensifying screens in clinical radiology. II. Examinations in clinical practice].

A clinically applicable procedure for testing new intensifying rare earth screens, as well as the special Siemens' screen is described. The results are related to universal screens. The film-screen combination alpha 4XD (gadolinium oxysulphide with normal, green sensitive film) results in a reduction of radiation dose to half with detail comparable with universal screens. The Siemens' special screen has similar advantages. Screens with a higher intensification factor and reduction of the mAs to one sixth results in loss of detail. This does not necessarily reduce their clinical use if they are used for appropriate purposes. The results of this clinically orientated technique agreed well with physically objective methods using lead grids. The advantages of the new screens are discussed in terms of their practical application.

Evaluation Studies as Topic↗