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Biomedical subjects

K Merkle

Publications and source records attributed to K Merkle.

At least 37 records · Page 2Linked to original sources
PubMed1989

[Results of intensive radiotherapy of bladder cancer following transurethral tumor resection].

During the period from 1977 to 1984 173 patients with a bladder carcinoma were exposed a combined operative-radiological therapy. It includes the transurethral tumor resection and the percutaneous high voltage irradiation after an interval of six weeks. After individual irradiation planning--since 1981 by means of CT--pendulum technique has been applied exclusively for careful treatment of risk organs. The total target dose (= 80% isodose) was 56 Gy with daily application of 1.8 Gy. We attained a 5-years-healing of 27%, obviously the first two years therapy beginning were deciding for fate (2-years-survival 45%). Among infiltration grade and histological type also the primary tumor localization had prognostic relevance. In locally advanced bladder carcinoma with invasion into the environment the radiotherapy gives chance for permanent healing. Acute passing side-reactions during intensive therapy, mainly as cystitis, we recorded in 2/3 of the patients. Only with the combined occurrence of cystitis and proctitis we had to record chronic effects in 2.5% of the cases for a period of more than 5 years.

Aged↗
PubMed1987

[Results of irradiation using different radiation sources in the treatment of malignant parotid tumors].

Patients with malignant parotid tumors were treated at two different centres with slightly ionizing radiation (110 patients) and neutron therapy (15 patients). The treatment results are compared. The principles of comparison applied in this analysis are identical. The histologic classification was made according to the W.H.O. recommendation of 1972 and the staging according to Becske. Local tumor control is the criterion applied in the comparative assessment of both methods. The analysis has shown that there is no significant difference in the treatment results within the individual stages of tumor's advancement after application of an orthovolt therapy and a telecobalt therapy. Patients treated in early stages (stages I and III) had a substantially higher rate of local tumor control (72%) than patients in advanced stages (46%, stages III and IV). A more favorable treatment results was achieved by neutron therapy in all stages of tumor's advancement. In this case the rate of patients with local tumor control (87%) was significantly higher than after radiotherapy with slightly ionizing radiation (46%).

Adenocarcinoma↗
PubMed1987

[A review. Current problems of experimental and clinical radiotherapy].

Although there has been dramatic progress in radiotherapy for several tumor types during the last decades, it cannot be overlooked that the overall success is far from being satisfactory. Since in the course of their disease, radiotherapy is indicated for more than two-thirds of cancer patients, improvement of treatment results become of great health-political importance. As a rule a successful procedure can be realized only, if radiotherapy is integrated into the multidisciplinary overall concept of cancer treatment and the patients will receive optimal attention in diagnosis, therapy and after-care in centralized oncological institutions. Based on the principle of individualized cancer therapy, possibilities are outlined to improve quality in carrying out the different steps of the process of radiotherapy. Special importance is attached to measures of the modification of the radiation effect. In particular, scientific tackle of questions of dose fractionation, the use of neutron therapy as well as radiosensitizers and protectors and of local hypothermia are considered starting points for further improvement of radiotherapeutic results. In addition to these problems, topical research tasks are outlined.

Fast Neutrons↗
PubMed1987

[Principles of dosimetric planning in contact therapy with highly active Cf-252 sources].

In clinical practice, some dosimetric problems of contact therapy with CF-252 are not yet sufficiently clarified. One possibility to solve these problems is to apply the conception of total photon-equivalent energy doses. This conception serves to calculate clinical guidance values of the RBE of the Cf-252 neutron constituent for radiogenic late effects in dependence on the total dose rate of the mixed radiation. The correlations indicated are valid for dose rates of 0.05 to 4 Gy/h and 4 to 1.25.10(4) Gy/h. On the basis of these functional correlations and taking into consideration the critical normal tissues of rectum and urinary bladder, the minimum RBE values of the tumors are indicated which allow a therapeutic effect of more than 1 in case of application of Cf-252. The formulas for the RBE dependence of the Cf-252 neutron constituent on the total dose rate permit to take into account any modifications of this value caused by varying source distances in contact therapy. It is concluded from these investigations that in oncologic patients, better results are to be expected from a treatment with high-energy Cf-252 sources, if the other treatment conditions are identical.

Brachytherapy↗
PubMed1986

[Cf-252 neutron therapy of cervical carcinoma: topometrical radiotherapy planning using an afterloading technic and computerized tomography].

The introduction of the afterloading technique with Cf-252 sources of high dose rate into the clinical practice has made necessary a topometrical radiation treatment planning (RTP) with increased accuracy in order to keep the risk of post-irradiation complications as low as possible. The possibilities of computerized tomography (CT) for topometrical RTP have been examined on 20 patients with histologically verified carcinoma of the cervix (stage Ia and Ib). The systematic use of the methods provides comprehensive information on anatomical relations and the localization of the applicator on all levels required for physical RTP. Thus, it was revealed that the cervix is enclosed by the bladder and that the distance from the dorsal wall of the bladder to the applicator in the cervical canal is, as a rule, not or little dependent on the level of bladder filling. By controlling the level of bladder filling it may be possible to reduce radiation load on the ileum, and thus to diminish the risk of radiation damage in case of intracavitary brachytherapy with Cf-252.

Brachytherapy↗
PubMed1986

[Topometric preparation of patients with cervix cancer for intracavitary irradiation on the ANET-B apparatus].

The authors worked out methods of topometric investigation of cervical cancer patients during preparation for intracavitary irradiation using 252Cf fast neutron sources. The use of balloon catheters made it possible to determine a coefficient of projection enlargement in the point of interest, to determine accurately the distance between endostats, sources and contrasted organs of interest: the bladder and rectum. The results of the studies were used for individual design of intracavitary treatment as well as for the determination of radiation exposure of the pelvic organs in 38 patients. The patients received a total of 138 investigations.

Brachytherapy↗
PubMed1986

[Analysis of the reproducibility of conditions of intracavitary irradiation of patients with cervix cancer].

The paper is concerned with the results of an analysis of reproducibility of conditions for intracavitary irradiation of 20 cervical cancer patients using metracolpostat, a combined therapeutic endostat consisting of 3 tubes: the central one to introduce radiation sources into the cervical canal and cavity of the uterus and 2 lateral ones with ovoids to deliver the sources to the vaults of the vagina. Topometric investigations for each patient were performed 4 times: before the first session of fractionated intracavitary irradiation with high activity 252Cf sources using the ANET-B unit and after each session of irradiation. It was shown that discordances between distances from the central endostat to the right and left lateral ovoids determined during roentgenotopometric preparation of each patient and taken as a basis of dosimetric design, and discordances between these distances determined as a result of roentgenotopometric control after each laying, are a random value distributed according to the normal law.

Brachytherapy↗
PubMed1984

[Computed tomography in the diagnosis of ovarian, cervix and uterine cancer].

By means of computer assisted tomography (CAT) 22 patients with ovarian and 13 with uterus cancer were examined for diagnostic reasons. The results were compared with surgical findings. The advantage of CAT over objective clinical examination was shown particularly in cases where the tumour goes beyond the organ and lymphnodes are affected. In spite of the high information value of the CAT a differential diagnosis is difficult in cases of ovarian cancer. The method is little effective in case of corpus carcinoma in the stage I. In 14 patients with cervix cancer it could be shown, that CAT is inefficient for an early detection of malignant tumours of this localisation. By means of CAT, however, one can get additional information about the spreading of the process, particularly in cases with relatively high localized and not well detectable by bimanuel examination and information to clear up concomitant diseases of pelvic organs as well.

Adult↗
PubMed1984

[The role of computerized tomography in the diagnosis and treatment planning of prostatic cancer].

The influence of computerized tomography on planning the therapy of 58 patients with histologically confirmed carcinoma of the prostate gland was examined. In classifying the early tumour stages there were differences from the clinical findings. With more advanced stages CT in some cases gave much more detail for diagnosing the extension. In 11.5% of the cases this led to the irradiation field being either enlarged or reduced. CT also proved to be useful for follow-up, especially as regards decisions on increasing the irradiation dose.

Aged↗
PubMed1983

[Computer tomography in determining lung density for irradiation planning].

The paper is concerned with the problems of the determination of lung density in the irradiation planning for thoracic tumors using CT. The mean value of density that was equal to 0.252 +/- 0.118 g/cm3 was obtained proceeding from a study of 118 CT sections of the lungs during quiet breathing. The respective value gets equal to 0.162 +/- 0.022 g/cm3 in deep breathing and 0.282 + 0.050 g/cm3 in full expiration. The values of lung density can vary in different persons. The range of measured values is equal to 0.119 = 0.441 g/cm3 in quiet breathing. The values of lung density vary within the limits of one section from the minimum value in its front part to the maximum one in the rear part. To determine lung densities that are representative for radiation therapy, CT should be performed with a patient breathing quietly in an uninterrupted manner. In significant deviations of density values from those accepted for isodose value calculation, individual consideration of lung density for each person is found appropriate.

Esophageal Neoplasms↗
PubMed1983

[Experience in using echotomography in planning the irradiation of cervical cancer patients].

A possibility to use echotomography (ET) in the topometric preparation of patients with cervical cancer for radiation therapy is shown. In addition to ET computerized tomography (CT) was performed to 15 patients at the level of classic points A and B. Proceeding from the results of both studies topometric maps were prepared. Using the maps distances between points of interest were compared. It was shown that the mean value of the distance from the middle of the uterine cervix to the bladder posterior wall was 24 and 23 mm in ET and CT, respectively. Some methodological problems of ET for irradiation planning are discussed. It should be noted that ET provides ample information on the small pelvic anatomical structures that are of interest in gamma-beam and intracavitary radiation therapy of cervical cancer. ET positive features are its safety for a patient, insignificant costs and an opportunity to get information for a 3-dimensional irradiation planning.

Female↗
PubMed1983

[Conventional roentgenologic methods and computerized tomography in the preirradiation planning for patients with esophageal cancer].

During the planning of irradiation of patients with esophageal cancer significant divergence is frequently noted between topometric maps obtained by conventional x-ray methods including axial tomography, and computerized tomography. Topometric maps based on these two methods were compared. Using a typical example of a series of 12 patients, divergences in expected dose loads on critical points were analysed on the basis of 3 variants of superposed topometric maps. Divergences in topometric maps result from errors in topometric methods and from an impossibility to reproduce precisely the level of a section and physiological conditions during repeated layings of a patient. Divergences in a focal dose (on the esophagus) can reach 8% in rotation radiotherapy, 20% in static irradiation, and on the vertebral canal 28 and 13% respectively. Factors that influence such divergences are discussed.

Cobalt Radioisotopes↗