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Biomedical subjects

B Kober

Publications and source records attributed to B Kober.

At least 19 recordsLinked to original sources
PubMed1992

[The surface dosage in the radiotherapy of a small breast carcinoma with 6-MV x-rays. A contribution to quality assurance in radiotherapy].

Radiation treatment of breast cancer with high-energy X-rays in breast conserving therapy tends to an under-dosage of the skin region. Results of our measurements with patients and in water demonstrate that the skin receives only 40% of the reference dose applying tangential opposed wedged fields with 6 MV X-rays. Doing so we must accept a dose inhomogeneity of about 60% in the target volume. That may cause an increased recurrence rate especially for superficially situated tumors and/or in the case of intraoperatively disseminated tumor cells. We show that utilizing bolus material of only 5 mm water equivalence on the skin above the tumor bed reduces the dose inhomogeneity to 8%.

Breast Neoplasms↗
PubMed1991

[Mounting devices for screening blocks on the linear accelerator--the drawbacks and modifications].

Block mounting devices for linacs--drawbacks and modifications: Shielding blocks are often used in radiotherapy. They are fixed on the linac's head by means of standard accessory mounting devices. The disadvantages of these parts are discussed and two modifications are presented: One device with adjustable focus-support distance for standard lead blocks and another with gliding planes to insert easily the heavy individually formed shielding blocks. Errors in mounting of all these devices are very dangerous, so we developed a simple locking lever providing a high security.

Equipment Design↗
PubMed1990

A psychological support concept and quality of life research in a liver transplantation program: an interdisciplinary multicenter study.

Considering the increasing number of liver transplantations with longer periods of transplant function, there is a growing need for quality of life research in the field. In addition to lethality, mortality and rehabilitation, parameters of 'quality of life' are to be evaluated: the patient's rating of his subjective physical symptoms, psychological condition (anxiety, depression and mental adjustment), social reintegration and life satisfaction. This paper describes our psychological support program that has been established at the Hamburg LTX center as well as the first results of the ongoing QoL research study. Using the methods developed by the Hamburg Study group on 'quality of life in surgery', 38 liver transplantation patients of the University of Chicago (cross-sectional study with control groups of patients with chronic liver disease as well as healthy individuals) and 29 patients of the University Clinic of Hamburg (longitudinal study with points of evaluation before and 2, 6, 12, 24 and 36 months after transplantation) have been evaluated. First results: (1) All successfully transplanted patients show a significant postoperative increase of their overall quality of life. (2) The psychological parameters of quality of life are only partly correlated with physical symptoms. (3) There is a high correlation between rejection crisis periods and the decrease of all quality of life parameters. (4) In both samples men have a lower quality of life than women, (5) Preoperative depression and lack of social support might be considered as being possible risk factors for long-term survival. (6) Long-term survivors rate their quality of life significantly higher than patients with chronic liver disease and--despite some persisting somatic restrictions--as high as healthy controls. (7) A psychotherapeutic support program increases the patient's compliance resulting a better adaption to the transplant procedure including rehabilitation.

Activities of Daily Living↗
PubMed1990

[A computer-supported method for the direct production of shielding blocks and compensators for radiotherapy].

The homogeneous irradiation of irregularly shaped targets with high doses and the simultaneous protection of the equally irregular surrounding high risk regions can be carried out with the help of shielding blocks and compensation filters specially cut for individual use. The machines offered on the market that help in their production have serious drawbacks in spite of the advanced technology used. These machines with limited usage are not only expensive but also require personnel to control the several steps the production of the blocks and filters involves. Safer radiotherapy however demands a more intensive use of these protective measures. However, it is now possible to overcome the drawbacks we have mentioned. The projection of the contours of the block marked on the X-ray on the shielding blocks can be carried out directly with the help of the computer that directs the radiotherapy. This computer could be connected to a multipurpose CNC milling machine. Similarly, one could, in the near future, use the data from computed tomograms in the computer used to plan the radiotherapy to mould three dimensional compensation filters. The cutting out of the negative moulds from Styrodur, the casting with fluid metal alloys, the imprecision that follows, as well as the health hazards and environmental pollution attached to his process could then be avoided, not to speak of the possibility of total reutilization of the rests. The positioning of the block ensemble can follow effortlessly and with precision on the lucite plates which have been drilled to accommodate the blocks.

Equipment Design↗
PubMed1989

Considerations on recombination losses in ionization chambers using pulsed electron beams with beam scanning.

Based on Boag's theory, referring to saturation effects in ionization chambers with pulsed electron beams, we developed a simple method of determining recombination losses. The correction factors for chamber readings result from slope and intercept of a regression line M1/3 = f(M/V) obtained with at least two different chamber voltages, V, and chamber readings, M. The deviation of these correction factors, compared with those of Boag's precise theory, does not exceed +/- 0.5%.

Electrons↗
PubMed1989

[Individual fixation during irradiation following breast-conserving surgery. Methodology and clinical results in 50 patients].

From February, 1986 through October, 1987, fifty patients with mammary carcinomas of the stages T1N0M0, T2N0M0, T1N1M0 and T2N1M0 were irradiated after breast-preserving surgery. The irradiation conditions were standardized with cobalt-60 gamma radiation or photons emitted by a linear accelerator and fixed oblique position in a specially manufactured, individual rigid foam bed. The position was checked every week at the therapy simulator with an analog tomographic attachment. The method, positioning in a 30 degrees oblique position and immobilization in an individually moulded rigid foam bed is described, and the necessity of regular tomographic controls in treatment position is underlined. Because of the short follow-up time of eight months, clinical results can only be presented with regard to early side effects and cosmetic results. A final assessment of this method is therefore not yet possible.

Adult↗
PubMed1988

[Results of palliative chemotherapy in advanced small cell bronchial carcinoma].

Results of chemotherapy for small cell bronchial carcinoma were analysed retrospectively on 36 of 40 consecutive patients with the disease, admitted to an oncology unit between January 1985 and December 1987. The survival curves indicated a highly significant trend (log-rank p = 0.001). Patients with extensive disease and Karnofsky index of 40-50% had a median survival of four months, but for those with Karnofsky index greater than 50% it was 15 months. There was virtually no age difference between the two groups, but there were significant differences regarding additional diseases (e.g. coronary heart disease, arteriosclerosis, etc.) frequency of liver and CNS metastases, rates of complete or partial remission, number of early deaths, haematological toxicity, and severe weight loss (greater than 5 kg). These results suggest that aggressive chemotherapy (primary designed for patients with limited disease) failed to improve the grave prognosis of patients with distant metastases and a low Karnofsky index (less than 50%). Supportive care should be intensified for these patients.

Adult↗
PubMed1988

[Dosimetry on a rotating phantom in remote electron irradiation].

The Therac-20 Saturne produces a high dose rate electron radiation allowing a whole-skin electron irradiation. The problem of producing large fields enclosing the whole patient has been solved by superposition of two tilted stationary fields. The angle regulations are optimized by a computer program fed with the TLD values of transverse dose distributions. A homogeneous irradiation is obtained by the patient's rotation on a turntable within the radiation field. In case of a distance of 3 m between focus and skin, the irradiation times are only 5 min for a body surface dose of 1 Gy.

Humans↗
PubMed1987

Effects of local irradiation and i.v. methotrexate on brain morphology in rabbits: early changes.

Brain damage following cranial radiation therapy can be crippling or even life-threatening and has been studied in both patients and animals. An additional toxic effect of chemotherapy has been found in children, who died following brain irradiation and systemic chemotherapy for the treatment of acute lymphoblastic leukemia. To study the interaction of radiation and drugs on brain tissue, we treated rabbits with brain irradiation and/or i.v. methotrexate. For a period of up to 3 months following radiation therapy, brain morphology was compared in seven treatment groups. Weekly doses of methotrexate administered i.v. produced no brain damage. Histological examination showed myelin swelling and beading 14 weeks after fractionated brain irradiation with 24 Gy. Combination of brain irradiation and methotrexate produced additional hypertrophy of microglia and pyknosis of adventitial cells. In none of these groups, even after doses of 48 Gy brain irradiation, was calcification or brain necrosis observed during the first 14 weeks following irradiation.

Animals↗
PubMed1987

Stereotactic percutaneous single dose irradiation of brain metastases with a linear accelerator.

The effectivity of stereotactic percutaneous single dose irradiations in the treatment of solitary brain metastases has been assessed in a series of 12 consecutive patients. Only radioresistant deeply localized metastases have been treated. Photon-irradiation was carried out with the convergent beam technique using stereotactic localization methods, in a linear accelerator facility. In 11 of the 12 patients no side effects occurred. The first 7 patients, who could be observed 3 months or longer, have been studied in detail. In each of these cases single dose irradiation with 20-30 Gy yielded arrest of tumor growth. In one case a marked decrease in contrast enhancement and in four cases shrinkage of the metastasis as well as a marked decrease of the edema occurred. In every patient a marked, sometimes dramatic improvement of the clinical condition was achieved, beginning a few days after irradiation. Stereotactic radiosurgery is a valuable tool in the treatment of inoperable, radioresistant brain metastases, the major advantage being high efficacy and smoothness of the procedure, as well as extremely short hospitalization times (2-3 days).

Adult↗
PubMed1987

[Results of radiation therapy in brain metastases with reference to computerized tomography].

Between 1979 and 1985, 193 patients were submitted to radiotherapy of the brain for formation of metastases. A primary irradiation was performed in 159 patients, 34 patients had been treated by surgery. The median survival time after diagnosis of all irradiated patients (40 to 60 Gy within four to six weeks) was 4.9 months, 22% of the patients survived one year. Patients with mammary carcinomas and patients with bronchial carcinomas showed marked differences in median survival times (4.2 and 6.9 months, respectively) and one-year survival rate (11% and 32%, respectively). In histologic examination, the extent of extracerebral formation of metastases was the decisive parameter for survival. At the end of radiotherapy, 47% of patients showed an amelioration in neurologic deficiency, 16% deteriorated. A follow-up by computed tomography with observation periods between four and 34 months was possible in 84 patients. Most of these patients showed improvement in computed tomography during a period of four to twenty weeks after the beginning of radiotherapy. Later on, about two thirds of the controlled patients had again deterioration with local progression or new formation of metastases in spite of total brain irradiation. A long-term normalization (greater than one year) was observed only in patients with mammary carcinomas.

Brain Neoplasms↗
PubMed1986

[Functional heterogeneity of liver metastases in 3-phase computerized tomograms].

Ninety patients with liver metastases (68 colorectal carcinomas, 22 breast carcinomas) were examined by triphasic angio-CT. This included demonstration of the entire liver after a bolus-like injection of contrast. Originally, the metastases were hypodense, but showed four patterns of contrast enhancement. Quantitative evaluation of the mammary carcinomas showed a marked increase in density during the bolus phase, with similar contrast values in the liver and at the centre and edge of the metastasis at ten minutes after the injection. Colorectal carcinomas showed only slight increase in density after contrast injection. The difference in density between the centre and the periphery of the metastasis was still present on later images. This finding indicates that there are differences in the vascularisation of these metastases.

Breast Neoplasms↗
PubMed1986

[Intra-arterial dynamic computed tomography in characterizing liver metastases of colorectal cancer].

Locoregional chemotherapy of liver metastases from colorectal tumours is a promising new approach. The results of CT in fifteen patients after intravenous and intra-arterial contrast injection are compared. The liver metastases are supplied mainly by the arterial route and this permits a means of assessing therapy. Contrast injections through a hepatic catheter may result in flow phenomena which limits the value of this investigation. It is unknown whether such flow phenomena may influence the result of intra-arterial chemotherapy. Although the margins of the metastases were more clearly defined, diagnostic accuracy was not increased, as compared with intravenous CT enhancement.

Colonic Neoplasms↗
PubMed1986

[Nuclear magnetic resonance tomographic staging of tumors of the oral cavity, oro- and hypopharynx and the larynx. A comparison with computed tomography and sonography].

Thirty-six patients with tumours of the mouth, the oropharynx and hypopharynx and the larynx were examined by nuclear resonance tomography. The results were compared with the clinical findings of inspection and palpation and with CT and sonography, with respect to T and N classification. In seven patients the classification could be confirmed at operation. NMR provides very good anatomical detail and marked contrast between tumour and the surrounding tissues, particularly on T2 weighted images. NMR showed the best correlation with the clinical findings as regards the T classification and was the most accurate method, as confirmed by surgery. It is superior to CT and sonography for diseases in the oropharynx and hypopharynx. For the examination of the cervical lymphatics, sonography remains the recommended method.

Adult↗
PubMed1986

[Radiotherapy of pathological fractures and skeletal lesions in danger of fractures].

Radiotherapy is of great importance in the treatment of pathologic fractures and skeletal lesions bearing the risk of fracture which are induced by malignomas, especially if these are in an advanced stage. In dependence on site and extent of skeletal destruction as well as on the general tumor dissemination, it can be distinguished between palliative radiotherapy and curative radiotherapy aiming at analgesia and remineralization. A retrospective analysis of 27 pathologic fractures and 56 skeletal lesions bearing the risk of fracture in malignoma patients showed an analgetic effect obtained by radiotherapy in 67% of pathological fractures and in 80% of skeletal lesions bearing the risk of fracture, whereas a remineralization could be demonstrated for 33% of pathological fractures and 50% of destructions bearing the risk of fracture. A stabilization of destructions progressing before therapy was found in 55% of pathological fractures and 40% of skeletal lesions bearing the risk of fracture. Thus a partial loading, supported by orthopedic prostheses, was possible for more than 50% of all patients.

Adult↗
PubMed1986

[Nuclear magnetic resonance tomography in the diagnosis of head and neck tumors. A comparison of methods].

36 patients with carcinomas of different ENT regions were investigated by means of MRI, CT and B-mode ultrasonography (US). The images were evaluated by parameters of clinical importance: tumour detectability marginal appearance, internal architecture, regional extension, and artifact degradation. The results were compared with the clinical tumour staging in accordance with the TNM system. In MRI, a multiplanar imaging of tumour extension with horizontal, frontal and sagittal sections is possible. Together with a good contrasting of the tumour against the surrounding structures, these are major advantages over CT in the imaging of carcinomas of the tonsils, the hypopharynx and the larynx. For both methods, tumours of the tongue base and the floor of the mouth are a real challenge. Lymph node metastases can be visualised with MRI, but US is the method of choice for the evaluation of cervical lymph nodes.

Carcinoma, Squamous Cell↗