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Biomedical subjects

K Merkle

Publications and source records attributed to K Merkle.

At least 55 records · Page 3Linked to original sources
PubMed1983

[Use of computed tomography for planning intracavitary radiotherapy of cervical cancer].

CT potentialities for irradiation planning have been demonstrated as a result of a study of 20 cervical cancer patients, Stages I-II, using a computerized tomograph for topometric preparation for intracavitary therapy with afterloading units, and subsequent gamma-beam therapy. Complete information on sections that are necessary for clinicodosimetric irradiation planning, has been obtained with the help of digital radiography, transversal tomography and mathematical reconstruction of secondary sections. The study was performed by inserting a centering mount and metrocolpostat after a preliminary determination of A point on the simulator. An effect of the degree of the bladder filling on the organs located in a given section has been shown. It has been established that the degree of the bladder filling at the level of A and B points does not influence a distance from its posterior wall to the metrostat. It is assumed that intestinal radiation injuries can be prevented by controlling the degree of the bladder filling.

Brachytherapy↗
PubMed1983

[2-dimensional ultrasonic scanning for irradiation planning].

The paper is concerned with the results of the utilization of echotomography in the topometric preparation of patients with malignant tumors for irradiation. Proceeding from the examination of 600 cancer patients in the All-Union Cancer Research Center. USSR AMS, it has been established that echotomography makes it possible not only to define the borders of pathology in the peritoneal cavity and retroperitoneal space but also to specify the relative position of the adjacent internal organs. Some practical aspects of the use of ultrasound for topometry are discussed. A possibility of using this method for the three-dimensional planning of irradiation is indicated. Using an echotomoscope one can obtain a contour of the section of a soft phantom with an accuracy of 5 +/- 1 mm that significantly exceeds the limits of precision of a contour measured with the help of a lead band where it equals 10 +/- 7 mm. Echotomography makes it possible to get a contour in any plane. In view of certain limitations of the echotomographic method one should also resort to x-ray methods for the topometric planning of irradiation to specify the position and size of the bearing osseous structures. While converting reduced ultrasound images in the scale of 1:1 the optic method with an episcope proved to be the most accurate one where an error of reproducibility of a contour reaches 1 mm. In the use of an optical-electronic device this value exceeds 10 mm and corresponds to 4 mm while utilizing a pantograph.

Humans↗
PubMed1982

[Effect of pulsed laser radiation on the lysosomes of Ehrlich ascitic tumor cells].

The results of a study on the effect of neodymium pulsed laser radiation on Ehrlich ascites tumor lysosomes are discussed. Tumor cell suspension was exposed in vitro to 10 pulses of laser irradiation with fluences of 10, 25 and 100 J/cm2, at a wavelength of 1.06 microns and a pulse duration of 1 microsecond. A rise in the free and total activities of acid phosphatase in the fraction of isolated lysosomes was registered one or four hours after exposure, particularly, at fluences of 10 and 25 J/cm2. However, laser radiation did not affect acid phosphatase activity in preparations of solubilized enzyme. Special experiments involving the use of detergents showed the increased activity of acid phosphatase in isolated lysosome fraction to be due to labilization of cytoplasmic membranes of tumor cells.

Acid Phosphatase↗
PubMed1978

Variation in U.V. primary fluorescence-intensity of vital cells depending on 60Co gamma-radiation dose.

Using impulse-cytofluorophotometry in the ultra-violet spectral region the author has shown on vital, unstained Ehrlich ascites tumour cells that the primary fluorescence intensity of this tumour is on day 11 after transplantation 20 per cent higher than on day 8. Storage of the vital cells for 25 min at 20 degrees C has no effect on this result. When the cells are exposed to 60Co to gamma-radiation on day 6, a new stable fluorescence level is established afted 20 hours. Measurements of the primary fluorescence intensity depending on dose have shown a significant rise starting from 75 rad at 48 hours after irradiation. The fluorescence intensity rises by 42.5 per cent of the control value at 3000 rad, but only by 31.5 per cent on exposure to 4000 rad.

Animals↗
PubMed1977

[Assesment of RBE of fast neutrons in Ehrlich ascites tumor cells by analysis of mitotic depression (author's transl)].

The depression of mitosis 1 hr following various doses of fast neutrons (6.2 Mev) and gamma rays was studied in an Ehrlich ascites carcinoma of mouse. Doses of 50, 100, 200 and 300 rad of either radiation yielded in the semilogarithmic plot a linear dose dependence of mitosis inhibition. From the regression straight line obtained the Relative Biological Effectiveness was determined, which declined from 2.8 at 50 rad to 1.8 at 300 rad neutron dose. The RBE is given analytically for the dose range investigated in dependence on neutron dose.

Animals↗