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Biomedical subjects

K Ewen

Publications and source records attributed to K Ewen.

At least 91 records · Page 5Linked to original sources
PubMed1979

[Determination of the quality of radiation and the dose rate in radiodiagnostics and radiotherapy by means of thermoluminescence dosemeters (author's transl)].

According to article 13, para. 1 of the Röntgenverordnung (regulations for the application of radiology) the dose rate of the useful radiation of radiotherapeutic units must be measured twice a year. The authors demonstrate that it is not absolutely necessary to use very complicated systems for these measurements which can also be performed with LiF thermoluminescence dosemeters. If CaF2 thermoluminescence dosemeters are used simultaneously, it is also possible to obtain an information about the quality of radiation.

Radiation Dosage↗
PubMed1978

[Dose reduction in xeromammography (author's transl)].

The use of a total filter of 3 mm of aluminium permits a considerable reduction of the radiation dose in xeromammography using the senographe. In comparison with conventional xeroradiography radiation is reduced by a factor of 2 to 3, in comparison with foilless film by a factor of 10 to 12. The applied tissue dose is between 0.14 and 0.30 rad per exposure. The presently still hypothetic radiogenic risk of carcinoma due to mammography is thus lower for this system than with other systems. The quality of the radiograph and the diagnostic validity are not reduced by this technique.

Female↗
PubMed1978

[Radiation exposure of the operator during angiography (author's transl)].

Radiation exposure to the forehead, hand, sternum and gonads of the operator was measured with a LiF dose meter during 134 angiocardiograms and 56 angiograms of the abdomen and the extremities. Average exposure during angiocardiography to the forehead was 3.2 mrem., to the hand 4.2 mrem. and the gonads and sternum about 0.5 mrem. per examination. During angiography of the abdomen and extremities, exposure was rather higher. The results of these measurements are compared with the findings of other authors and relate to dose-dependant somatic damage.

Angiocardiography↗
PubMed1978

[Value of different systems of mammography records with regard to their exposure to radiation and their information content (author's transl)].

We learned from our examinations that, if there were optimum conditions, the combination Medichrome MR50 as a form of low dose method offers the same information content as the film without intensifying screens PE 4006. We found out that the discernibleness of details of 70 non selected mammographies which had each been taken by both systems was absolutely identical. By xeroradiography, however, a more precise representation of details, especially if there are microcalcifications, is possible because of its effect which renders the edges more visible. If the Medichrome low dose method was applied, the exposure to radiation of the breast was, depending on the density and width or the organ, only 1/12 to 1/14 of the dose measured if the film without intensifying screens was used. The exposure to radiation connected with xeroradiography is between these two values. We came to the following conclusion: the low dose method is recommended for routine mammographies, and only if there are special problems or if suspicious findings are to be clarified, xeroradiography is applied as supplementary examination method. Before using the film without intensifying screens, one should consider the high radiation exposure which, however, does not involve a greater information content.

Breast Neoplasms↗
PubMed1978

[Diagnostic significance of high-filtration xeromammography in relation to radiation hazard and image quality (author's transl)].

The use of additional filtration through 3 mm aluminium enables significant reduction of the radiation dose in xeromammography with the Senographe, compared with conventional xerography, by a factor of 2-3, and, compared with film not requiring an intensifying screen, by a factor of 10-12. The applied tissue doses are between 0.14 and 0.30 rad per exposure. Hence, the radiogenic carcinoma risk, which is still largely hypothetic, is very low as far as this mammographic system is concerned. The high quality of the mammographs guarantees absolute diagnostic safety.

Filtration↗
PubMed1978

[Possibilities of dose reduction in extramammographic xeroradiography (author's transl)].

The soft radiation within the inhomogeneous spectrum of bremsstrahlung, being unable to penetrate the object and not contributing to the build-up of the xeroradiographic picture, only being the cause of additional radiation exposure, is considerably reduced by means of added filters, copper filters in particular. This effect can be demonstrated qualitatively by means of the recorded X-ray spectra. In comparison with the standard record it is possible by hardening of the radiation to reduce the surface dose by a factor 8 at a tube voltage of 120 kV, and by a factor 10 at a tube voltage of 130 to 150 kV if a 0.5 mm thick copper filter is added. The surface dose measured with high-filtration in xeroradiography is within the same order of magnitude as the dose obtained with a conventional film-foil-combination (Cronex 4/Cawo high-definition foil, 75 kV, automatic exposure control, time of development 90 s) and amounts to circa 0.1 R. A loss of information in so-called high-filtration xerograms as compared to conventional xerograms could be excluded, at least with regard to the test object. The practicability of this method e.g. for angiography, particularly angiographic exploration of the limbs, needs further clinical examination.

Angiography↗
PubMed1977

[Recent data on the radiation exposure to the patient in diagnostic radiology (author's transl)].

As a consequence of the x-ray decree (GFR 1973) data are obligatory to assess the radiation exposure to the patient. These data can easily be obtained with an additional device for recording the dose surface product. The value of the fluoroscopy time for calculating the radiation exposure of different organs is discussed. By a high standard of technical equipment and training of the technical personnel, radiation exposure to the patient may be kept low. Recent data on the exposure to the patient in diagnostic radiology and the corresponding somatic and genetic hazards are summarized in this review.

Body Weight↗
PubMed1977

[Actual radiation hazards for the examiner in diagnostic radiology (author's transl)].

Few data are available about radiation exposure of the physician in diagnostic radiology. They are in a range of greater than or equal to 0.1 to 40 mrads per examination. A whole body exposure of approximately 20 mrads per week may result from a rather high frequency of examinations. This value corresponds to 1/5 of the dose limit for radiation workers per week. At the present time, there is no evidence that exposures at such low doses and dose rates increase the genetic and carcinogenic hazards of radiation workers.

Germany, West↗
PubMed1977

[The medical uses of radio-active substance in North Rhine-Westphalia during the last ten years (author's transl)].

On 1st April 1977, legislation for protection from ionising radiation has replaced the law of 24th June 1960. This appears to be an appropriate occasion to consider the medical use of radioactive substances in North Rhine-Westphalia in the last ten years. The supervisory function of the competent authority has been statistically investigated. The extent to which the most commonly used controlled radioactive substances are employed in medical practice has been studied. The controls used and the radiation dose received by personnel are summarised.

Body Burden↗
PubMed1977

[Gonadal dosis in intravenous urography and voiding cystourethrography of children (athor's transl)].

Measurements of gonadal doses of 92 children during intravenous urography and voiding cystourethrography are reported. The high deviation of doses in the testes is discussed. The application of a lead protector for the testes is demanded to decrease exposure by a factor 15 in the central beam and a factor 1.3-2 in scattered radiation. By choice of spot film radiography instead of large radiography the ovarian dose is reduced to a factor 7-40. The gonadal dose is clearly lower if 70 mm technique instead of large film technique is used. A correlation between area ionisation product and gonadal dose could not be found; therefore the genetic radiation dose cannot be calculated by data recorded as required by law.

Child↗