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Biomedical subjects

A Kriester

Publications and source records attributed to A Kriester.

At least 19 recordsLinked to original sources
PubMed1989

[Results of combined operative-radiologic therapy of bladder cancer from the viewpoint of optimizing the physical-technical irradiation planning].

In 294 patients with bladder carcinoma, in which after transurethral or transvesical operation a high-voltage irradiation with daily 1.5 Gy and a total target dose of 60 Gy (four fields cross firing technique) was done, the influence of quality of physical-technical irradiation planning is studied on survival rates, portion of recurrences, side-, and late effects. The group of patients with individually computer-based optimizing of irradiation parameters based on a patient's cross-section, ascertained on therapy simulator, significantly shows better results with regard to above-mentioned criteria than the groups of patients with standard irradiation technique without and with definition of bladder topography.

Aged↗
PubMed1988

[A prospective randomized study on the fractionation of afterloading therapy of cancer of the cervix and endometrium].

A prospective randomized clinical study is made on patients with uterine cervix and endometrium carcinomas treated only by radiotherapy. The fractionation schemes of 4 times 10 Gy, and 5 times 8 Gy, and 8 times 5 Gy at the reference points A and My, respectively, of a short-term afterloading therapy combined with percutaneous telecobalt therapy with 45 Gy at the pelvic wall are investigated. A tendency is shown towards better tumor control and less radiogenic effects with an increased number of fractions. The results are discussed on the basis of the NSD and LQ models. The problems caused by the equipment type and dosage specificity hampering the applicability of the results on other afterloading therapy units are pointed out.

Aged↗
PubMed1988

[Dose-time optimization in fractionated radiotherapy].

On the basis of an evaluation of different isoeffect correlations for normal tissue reactions supported by a clinical study, a number of correlations for the dose-time optimization of irradiations with equal fractionation intervals are derived from a simple approach for the survival rate of irradiated tumor cells based on a linear quadratic dose-effect function for an exponential cell proliferation. This allows to determine optimum single doses for every given fractionation interval which, applied with the number of fractions tolerated by normal tissue, lead to a maximum reduction of tumor cells. The values of these optimum fractionation parameters depend from cell proliferation and radiosensitivity of the tumoral tissue and vary with respect to a normal tissue tolerance for early and late reactions. The results are described for several fractionation examples. It is shown that, within the tolerance limits of normal tissue, a greater tumor remission is achieved by hyper-fractionated irradiation than by a small number of high-dose irradiations.

Dose-Response Relationship, Radiation↗
PubMed1986

[Histologic changes in the normal bladder wall following fractionated irradiation--an animal experimental study].

The histopathologic alterations of the bladder wall were investigated in 180 rabbits irradiated with different fractionations and total focal doses. Animals sacrificed on week after the end of irradiation showed alterations of the urothelium (desquamation, increased polymorphism of nuclei vacuolizations) as well as oedematous and hyperemic reactions in submucosa and muscularis. These alterations became stronger when the single and total focal dose and the ret value were increased. Animals sacrificed three to six months after the end of irradiation showed dystrophic-sclerotic processes as well as vascular obliterations in the submucosa and muscularis. The alterations were only clearly visible in case of a total focal dose of at least 30 Gy. With regard to a minimization of histopathologic alterations of the bladder wall, a fractionation of 1.5 Gy per day has to be considered as favorable in radiotherapy of the carcinoma of the urinary bladder.

Animals↗
PubMed1985

[Results of percutaneous radiotherapy of bladder cancer using 1 and 2 series of irradiation].

In a randomized prospective clinical study, the authors investigate the results of percutaneous radiotherapy (telecobalt) with two rhythms of fractionation in patients with vesical carcinomas. A one-series irradiation with 1.5 Gy daily (except the weekends) up to a total dose of 60 Gy is compared to a two-series irradiation (in the first series 3 Gy three days per week up to 30 Gy, then irradiation-free interval of four weeks, in the second series 1.5 Gy daily up to a total focal dose of 60 Gy). The five-year survival rates are 52% after one-series irradiation and 39% after two-series irradiation. The surgical treatment consisted in a most radical resection of the vesical tumor by TUTUR, partial resection of the wall, of transvesical tumor resection.

Aged↗
PubMed1985

[Results of radiotherapeutic optimization within the scope of combined operative-radiologic therapy of urinary bladder cancer].

The results of a prospective randomized clinical study for the comparison of a uniserial irradiation with a biserial irradiation are demonstrated. The investigations were performed on altogether 191 patients. Patients after cystectomy and supravesical by-pass of the urine were excluded. The operative treatment consisted of TUTUR, transvesical tumour resection or partial resection of the urinary bladder. According to the life table method the uniserial irradiation a survival rate of 52% and for the biserial irradiation of 39% after 54 months was calculated.

Aged↗
PubMed1982

[The problem of preoperative radiotherapy of renal adenocarcinomas from the viewpoint of tumor biology].

Tumour biological examinations were carried out on 26 patients with pulmonary metastases of renal adenocarcinomas; growth functions were used to calculate the point in time at which metastases began to grow, in relation to the time of operation. The aim was to derive information on the indications for pre-operative radiation therapy. In 3 patients out of 26 (11.5%) there is an indication for pre-operative irradiation. For comparative clinical tests on the value of pre-operative irradiation a minimum of 871 patients are needed in each group for comparison to evaluate the 3-year survival rate and 489 patients to evaluate the 5-year survival rate in order to be certain of the positive effect of pre-operative irradiation with 1% statistical probability. Our examinations are to be considered as a model.

Adenocarcinoma↗