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Biomedical subjects

K Mück

Publications and source records attributed to K Mück.

6 recordsLinked to original sources
PubMed2000

Design and dosimetry of a novel 90Y beta source to prevent restenosis after angioplasty.

PURPOSE: Post-dilatation irradiation of the vessel wall is currently under investigation for prevention of restenosis after balloon dilatation. For the irradiation, special sources were designed for animal experiments which would give equivalent irradiation conditions and doses to the vessel wall that would later be employed for human application. METHODS AND MATERIALS: For the planned irradiations, a specially designed yttrium-wire of 0.45-mm diameter coated with a thin shrink tube to prevent contamination was deployed. Several leakage tests applied before and after application proved that the irradiation source was leakproof. Dosimetry was performed by using 0.1-mm-thick thermoluminescent dosimeters (TLD-100) calibrated against a primary standard. A shielding transport and application container was designed to facilitate the handling of the source during use, while reducing exposure of the medical personnel. RESULTS: The designed source proves to be flexible for the insertion into proximal coronary vessels, and positioning at the site of stenosis. It provides an optimum protection of the animal and requires little radiation protection efforts on behalf of the medical staff. Dosimetric calculations and measurements showed that a centering of the source inside the vessel could be achieved with a maximum deviation of 50% between maximum and average dose levels. CONCLUSION: A yttrium-90 beta brachytherapy source was designed which provides high flexibility within proximal coronary arteries, ensures an adequate centering inside the artery, and provides irradiation conditions to the vessel wall of the experimental animal comparable to the application inside a human artery.

Angioplasty, Balloon, Coronary↗
PubMed1997

Long-term effective decrease of cesium concentration in foodstuffs after nuclear fallout.

The long-term decrease in activity concentrations in various foodstuffs relevant for the long-term ingestion dose after a nuclear fallout is reviewed. The effective decrease observed in various countries of Central Europe after the Chernobyl accident are compared to the effective decrease observed after the atmospheric nuclear weapons testing. The presentation also includes the short-term decline immediately after fallout and the time course in the first year, which are relevant to the first year ingestion dose. The initial effective decrease is dominantly controlled by plant growth and follows an approximate half-life of 4.2 d in lettuce and spinach, and 10.5 d in grass during the growing season, resulting in an effective half-life of 33 d in milk. In order to avoid artifacts due to local fallout or plant variations or differences in the metabolism of single animals, the sampling of each foodstuff was spread over very large areas of production and a large number of samples including investigations in several individual provinces. The long-term decrease over the following years, which is vital for the long-term internal exposure, is slower but still follows an effective half-life for different foodstuffs: milk = 1.4-2.2 y, vegetables = 1.4-2.7 y, potatoes = 2.0-2.6 y, cereals = 3.0-3.4 y, and fruit = 1.2-1.6 y. Differences observed between the different products and areas are discussed. Half-lives in milk vary between three central-European countries from 708 d (Austria), to 663 d (Germany), to 538 d (Czechia). The observed effective half-life is much shorter than observed after nuclear weapons testing where a half-life of approximately 4.5-4.9 y was observed, which is explained by the weapons tests' fallout lasting for several years compared to the single short-term fallout after the Chernobyl accident.

Animals↗
PubMed1995

Longterm reduction of caesium concentration in milk after nuclear fallout.

Time trends in activity concentrations in milk as observed in Austria after the Chernobyl accident are presented. Both the short term decrease immediately after fallout and the medium term decline in the years following the event are very important for estimating the total exposure to be expected from a given deposition. In order to avoid artifacts due to local fallout, plant variations, or differences in the metabolism of single animals, large areas of production were used for the observations. This was achieved by observations of activity concentrations in milk powder, produced in large milk powder plants in Austria. After an initial decay with an approximate half-life of 34 days for the period of May to August 1986, a slower decrease in activity was observed during the following years. Observed half-lives are in the range of 1.5-2.0 a. Differences in the decrease observed between the different producing areas are discussed. The radiocesium contamination of milk and milk products depends directly on its presence in grass or hay and therefore, time trends observed in milk correspond closely to the time trend in these fodders. Other foodstuffs which are also produced on grass and hay, such as beef or lamb, should therefore display similar decay patterns, except for the early period after fallout when the biological half-lives in the animals influences the decrease.

Animals↗
PubMed1990

Estimate of the dose due to 90Sr to the Austrian population after the Chernobyl accident.

In order to estimate the contribution of 90Sr to the exposure of the Austrian population, the ratio of 90Sr to 137Cs in 126 food samples and nine drinking water samples was determined. From this and the average activity concentration of 137Cs in each type of food as obtained by the measurement of some 100,000 food samples after the Chernobyl accident, a good estimate of the average activity concentration of 90Sr in these food items could be obtained. Samples were investigated at various times after the accident to take into account possible changes with time in the 90Sr-activity concentration and its ratio to 137Cs. Also, pre-Chernobyl samples were measured to estimate the relative contribution of the reactor accident and the fallout of the atomic bomb testing to the intake of 90Sr. Assuming average food consumption, the intake of 90Sr for an adult person amounted to 168 Bq in the first year and 115 Bq in the second year after the accident, resulting in an effective dose equivalent of 5.9 muSv and 4.0 muSv, respectively. This is a minor fraction of the dose due to the ingestion of Cs isotopes, which amounted to 360 muSv in the first year and 97 muSv in the second year. For the one-year-old infant, a 90Sr intake of 96 Bq (10.5 muSv) in the first year and 65 Bq (7.1 muSv) in the second year is estimated. Approximately 50% of the intake in the first year and 70% of that in the second year are due to 90Sr from nuclear weapons testing.

Accidents↗