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Biomedical subjects

W Seeger

Publications and source records attributed to W Seeger.

At least 379 records · Page 21Linked to original sources
PubMed1980

[Demonstration of ultra-hard X-radiation by means of silicon photo-elements (author's transl)].

Commercial silicon photo-elements were irradiated with 8 MV X-rays and 10 MeV electrons in the linear accelerator SL 75/10, and their usability as monitors and dosemeters was examined. The short circuit current of the photo-elements, which is linear to the transmitted dose rate, was measured with an expressly developed impulse amplifier which is sensitive to electricity. Further examinations as to the energy dependence proved a nearly constant sensitivity within the scope of 1 to 10 MeV. However, there are irradiation damages within this scope, which lead to a decrease of the sensitivity to photo-electricity producing a degeneration rate of 100 to 9 MGy-1. The examination showed on the other hand that, because of their simple measuring principle, the easily reproducible results, and the high sensitivity, the photo-elements can find various applications as monitors with direct display for relative measurements.

Mathematics↗
PubMed1979

[Techniques and results after embolization of meningiomas (author's transl)].

The different techniques and results are described for a total of 25 preoperative tumor embolizations in 21 patients with meningiomas of diverse localizations and extents. Transfemoral catheter techniques were superior to direct punctures of the carotid arteries because of the easier handling of the catheters, the better superselectivity of angiography, and, consequently, the more exact placement of the emboli. The results of the embolizations depended on the localization of the meningiomas. Meningiomas of the convexities (six patients) turned out to be particularly susceptible to complete embolizations. Satisfactory results were achieved operatively and histologically through embolization in meningiomas of the falx with large parasagittal expansion as well as in those of the lateral sphenoid wing, the sylvian fissure, and the cavum Meckeli (nine patients). Embolization of tumors which were localized exclusively at the falx, the tentorium, or of more medially situated meningiomas of the sphenoid wing were without beneficial effect, since these are predominantly vascularized by branches of the internal carotid arteries. Provided the localization and vascularization of a tumor are favourable the application of superselective angiography and preoperative embolization represents an important improvement of the basic conditions for a later operation.

Adult↗
PubMed1978

Microsurgery of tumours of the frontal white matter.

Seventy eight microsurgical extirpations of tumours located in the frontal white matter led to adjustment of the normal anatomy of the frontal brain according to microsurgical requirements, and also to relation with modern diagnostic procedures, especially computerized tomography (CT-scanning). The advantages of microsurgical treatment have been demonstrated. Thus, only exact comprehension of topographical anatomy allows a methodical, careful, and radical procedure. As vessels were commonly saved, postoperative courses were relatively benign because of less tendency to oedema. Out of 78 patients, 3 died while in hospital, and two recurrences were observed in the following 23 months. Postoperatively 51 patients improved, 18 stayed unchanged neurologically, and 9 patients deteriorated permanently. The usual microsurgical instruments were employed. Vascular problems were dealt with by the routine techniques used at our hospital.

Astrocytoma↗
PubMed1978

[Microsurgery of sphenoidal ridge meningiomas (author's transl)].

On the basis of 22 sphenoidal ridge meningiomas operated on in the last two years, the topographical relationship of these tumours to the brain and the base of the skull is described. The microsurgical technique which is used is described and its advantages discussed.

Adult↗
PubMed1978

[Results of 289 cadaver kidney transplantations at the Berlin-Friedrichshain centre (author's transl)].

Developement and organization of kidney transplantation in the GDR was studied, with data of 289 patients who underwent transplantation at the Kidney Transplant Centre, Berlin-Friedrichshain being analyzed. The five years graft survival was 42% and the patients survival 62%. In case of combined treatment of transplantation and dialysis it was 70%. The main cause of transplant failure was rejection with a frequency of 12,1%. On the basis of an improved immunosuppression regime the mortality rate decreased from 37,6% to 12,3%. The introduction of a new method of ureteroneocystostomy resulted in a lower rate of urological complications. The importance of the preparation of the recipients, of the HLA-tissue typing as well as the influence of blood transfusion on the late prognosis of grafts will be discussed.

Berlin↗
PubMed1977

[The microsurgical treatment of the so-called tuberculum-sellae-meningiomas (author's transl)].

Experience from five cases operated on within one year (among 50 microsurgical operations at the base of the brain) persuades us to discuss the topical relations of the meningiomas of the tuberculum sellae and the modifications in operating techniques necessary. For the two contrasting types of tumour found, which are:-- 1. Tumours en plaque with osseous reactions, particularly of the sphenoidal ridge, in which the exact predetermination of the positions of the optic nerve and of the carotid artery is facilitated by means of measurement and by fronto-temporal approach (which does not preclude a frontal or a bifrontal approach). 2. Suprasellar tumours whose topical relationships to the posterior surface of the chiasma, the pituitary stalk, the big vessels, and the perforating arteries increase the risk of operation. Radical operations for tumours near the pituitary stalk are not always advisable. Pre- and postoperative analysis of the anatomical characteristics of the individual case is essential before microsurgical intervention.

Aged↗
PubMed1977

[Comparison of myelographic and operative findings in lumbar disk lesions (author's transl)].

A comparative study has been made of the myelographic, clinical and operative findings in 140 patients with lumbar disk lesions. The myelographic and operative findings corresponded in 95%. The L 4-5 disk was the most frequently affected. With regard to the operation, some of the most important technical points are discussed. A myelography is strongly recommended before every disk operation.

Adolescent↗
PubMed1977

Long-term haemodialysis-an enhancing factor for cadaveric graft survival.

In 220 consecutive cadaveric kidney transplants, graft survival in patients dialysed for a period of two years or longer was significantly greater than in those dialysed for less than two years. More blood transfusions were received and the formation of HLA antibodies was greater in the group dialysed for more than two years. A positive cross match was the basis for excluding 21% of the HLA positive patients from transplantation during a one year period of observation. When these same HLA positive patients had more than two subsequent opportunities for donor-recipient selection the exclusion rate dropped to 2%. The longer period of dialysis with more blood transfusions had a favourable influence on cadaveric graft survival whereas the formation of HLA antibodies had a negative influence. Even in HLA positive patients graft survival was better in the long-term dialysis group when compared with the group dialysed for a shorter period. These results suggest that longer dialysis with more blood transfusions represents an enhancing factor for cadaveric kidney grafts.

Blood Transfusion↗
PubMed1977

[Embolization in neurosurgery (author's transl)].

Based on the literature and own experiences the indications for embolization in neurosurgical diseases are presented. This procedure is used for the treatment of arteriovenous malformations and fistulas, preoperatively in richly vascularized neoplasm and non operable tumors. Modern techniques (super-selective angiography, double-lumen balloon-catheter and catheters with detachable balloons) enable to occlude the territory of A. carotis ext., the cavernous portion of A. carotis int., the cervical portion of A. vertebralis, and the dorsal spinal radicular arteries. Complications are rare. There is a limited indication for embolization of the intracerebral area and the territory of A. spinalis and the ventral radiscaular arteries because of additional damage of the central nervous system. Various techniques and possible complications are discussed and own cases are presented.

Basilar Artery↗
PubMed1977

[Dosimetry using the linear accelerator (author's transl)].

On the basis of data employed in radiation therapy with megavoltage X-radiation from the linear accelerator Philips SL 75/10 have been developed clearly arranged and practicable treatment schedules for the use of the radiotherapist. Application of a fixed focal dose, for instance 250 R per session, makes the number of days needed for irradiation easy to calculate. The possible field sizes are classified with regard to equivalent relative deviations at the class limits, and represented by a pattern of diaphragms. Thus, and by the use of constant focus-skin distance of 90 cm, well-arranged tables are obtained. Two-year experiences with the utilization of these schedules as well as the check-up by daily measurements and the necessary controls of operating conditions are summarized in diagrams.

Humans↗
PubMed1976

[Microsurgery in pre-pontine tumours (author's transl)].

On the basis of some selected examples, the problems of micro-surgical operations on parasellar and pre-pontine tumours are discussed. The tumours are divided into five types, according to their localisation. The particular anatomical aspects are discussed in detail.

Adolescent↗
PubMed1975

[Internal fixation with soft-tissue lesions: fracture with nerve damage (author's transl)].

Typical nerve damage after fractures due to the topographical proximity of the nerves to the bones, are shown and therapeutic principles are discussed. Primary traumatic lesions are differentiated from so-called "creeping paralysis". The methods of choice are neurolyses, nerve suture or transplantation, each at the appropriate time. Evaluation of 83 of the 128 Patients undergoing microsurgical operations on the nerves in recent years is presented after re-exmination by independent neurologists. One-third showed definite signs of regeneration, more than one-third had good functional results, and poor results were recarded for 25 percent of the patients.

Fractures, Bone↗
PubMed1975

[Diagnostic possibilities of positive contrast ventriculography (author's transl)].

A comparison has been made of the relative merits of air, Conray 60, and Dimer X ventriculography in 100 cases. The great virtue of positive contrast ventriculography is its superior ability to demonstrate abnormalities in the midline and in the posterior cranial fossa. Tomoventriculography using a multiple layer cassette permits exact localization of intraventricular lesions without causing additional discomfort to the patient. The subtraction technique confers additional benefits. Positive contrast ventriculography has its limitations when there are large extraventricular masses.

Adult↗
PubMed1975

[Dose distribution and irradiation technique in the radiotherapy of breast cancer stage I].

A method for homogenous irradiation of the breast by means of opposite standing fields, with the use of wedge filters, is described here. The field is focussed so that the interior thoracic wall under symmetric position of the mamma is still completely situated in the irradiation field, and the lateral area of the ray beam passes 1-2 cm into the pulmonary tissue. On a series of typical breast models, made under consideration of the irradiation position, the isodose distributions were determined by film-dosimetry. The therapeutically most important 80%-isodose corresponds in practically every case with the mamma contour. Peak doses or areas of underdosage were not observed. The thoracic wall is still exposed to about 75% of the maximum dose. In order to reach a more accurate irradiation by the desired maximum dose of, for example, 250 r, the deviation of which does not exceed plus or minus 7%, it is necessary, at the beginning of an irradiation series, to use ionisation chamber measurements with an intensifying hood on the surface of the mamma, 1.5 cm above the border of the field. In the case of lateral irradiation, the measurement need only be made laterally, in medial irradiation it is only necessary on the medial side. The portion of the dose affecting the opposite field on the measuring place can be calculated by the use of depth dose tables. From the values so gained the desired maximum dose within the mamma may be ascertained by multiplication by the factor 1.03.

Breast Neoplasms↗