Gamma-Ray Emitting Radionuclides in People Living in Northern Sub Arctic Regions

In 1960 Caesium-137 activity from atmospheric nuclear weapons test was discovered in measurements at the whole body gamma-ray counting laboratory in Lund. This event initiated measurements of the Swedish Sami population, and in products from reindeer that bite lichens in the Swedish mountains. A semi-portable whole-body counter designed with a detection limit for 137Cs at high radiation background areas which was good enough for measuring people with high body concentration of 137Cs. The 137Cs activity concentration in Sami people increased during 1963–1965 from 300 to 600 Bq/kg body weight. Some individual males had values above 1000 Bq/kg. The catastrophic nuclear accident on the 25–26 April 1986 at the Chernobyl Nuclear Power Plant caused a massive release of fission- and neutron-activation products to the atmosphere. Already the following day the atmospheric plume of released radioactivity reached Sweden and was deposited over the central part of Sweden also in Sami populated reindeer raising districts. During 1991 and 1992 whole-body content of 137Cs was measured in the Sami population of northern Sweden and similar levels were found as during 1963–1965. These levels are about twice those estimated in people living in the Chernobyl contaminated area

Gel chromatography column scanning for the analysis of 99mTc-labelled compounds

The gel chromatography column scanning (GCS) method has been studied, special attention being paid to its suitability for the analysis of 99mTc-labelled compounds and radio-pharmaceuticals. The sample to be analyzed was applied at the top of a column filled with Sephadex G gel. Elution was carried out with 0.9% sodium chloride solution with such a volume that all the radioactivity was retained in the column. The column was then sealed and scanned with a 1 mm slit-collimated NaI(Tl) crystal. The GCS method is discussed and different factors influencing the scanning profile are considered. The relationship between the position of the activity peak in the scanning profile and the molecular weight of the sample is given for Sephadex G-25 Medium gel

Labeling plasmin with technetium-99m for scintigraphic localization of thrombi

A detailed study has been made of the method for labeling plasmin (NOVO Indstri A/S Denmark) with 99mTc in order to prepare a radioactive indicator for early scintigraphic visualization of thrombi and tumors. The best method found for preparing 99mTc-plasmic involved the reduction of 2.5 ml 99mTc-pertechnetate solution with 0.5 ml of 4 mM SnCl2, 2 M NaCl and 70 mM HCl. This mixture was then added to 5 mg of plasmin to give a final pH of about 2. After 60 min of reaction the labeling efficiency was 80-90% as determined by gel chromatography column-scanning. The labeling kinetics and influence of pH, concentration of SnCl2, NaCl, plasmin and lysine were studied. The enzymatic activity of plasmin was reduced by less than 15% by the labeling process. Preliminary experiments in rabbits with artificially induced thrombi indicate accumulation of 99mTc activity in the same areas as 125I-fibrinogen after the administration of 99mTc-plasmin

Quality control of 99mTc-radiopharmaceuticals - Evaluation of GCS minicolumns in routine clinical work with scintillation cameras

Gel chromatography column scanning (GCS) is a rapid and reliable method for the quality control of 99mTc-radiopharmaceuticals. With this method the labelled compound and various impurities such as free pertechnetate, hydrolyzed reduced technetium or other 99mTc-complexes are obtained in one testing procedure. Using minicolumns results can be obtained with a simple testing procedure within a few minutes after the sample is taken; this is significant in routine radiopharmaceutical work. The resolution of the recording system is important, so as to be able to utilize fully the good separation ability of the minicolumn. Minicolumns were studied with some commonly used radiopharmaceuticals. A scintillation camera was used to record minicolumn data under various conditions and the results were compared to those obtained using a scanner to reveal optimal recording conditions for the scintillation camera

Global fallout of curium

THE search for 242mAm (t1/2=152 yr) in environmental samples has involved detection of its daughter 242Cm (t 1/2=163 d) (refs 1-3). These samples were contaminated by transuranium nuclides either from a nuclear fuel reprocessing plant or from a thermonuclear test fallout. A logical consequence was then to analyse global fallout-contaminated samples for 242Cm and 244Cm to establish the present distribution and global contamination of our environment by these transuranium elements. We have chosen the lichen Cladonia alpestris, which is an excellent bioindicator for atmospheric fallout and we present the results here. The samples have been stored in the laboratory for 5-16 yr. Thus, 242mAm and 242Cm were in sequelar radioactive equilibrium. The 242Cm present in the aged samples therefore represents the 242mAm present in the fallout. The results indicate a 242mAm/239+240Pu activity ratio of about 0.003% in global fallout

Safety aspects of magnetic resonance examinations

No Abstrac

Polonium-210 in the bio-sphere : Bio-kinetics and biological effects

Polonium-210 is an alpha particle emitting radioactive element with a half-life of 138 days. It appears at the end of the decay-chain of Uranium-238 where the long lived Lead-210 (22.3 a) decays to Bismuth-210, and finally Polonium-210. 210Po is introduced into the biosphere through various routes of terrestrial and marine radioecological pathways. The level of 210Po activity in drinking water (5 Bq.kg-1) and in most common food items of terrestrial origin are usually low (0.04-0.1 Bq.kg-1 wet mass) and considered to be without concerns for human health. In some terrestrial food items such as reindeer and caribou, high 210Po levels (10 Bq.kg-1 wet mass) are due to their habit of grazing lichens (250 Bq.kg-1 dry weight). The food chain lichen-reindeer and man in arctic and sub-arctic regions is a unique pathway of 210Po to man. The enhancement of 210Po concentrations is also very pronounced in marine organisms feeding upon phytoplankton at the base of the food chain. Fish and seafood therefore have high activity concentrations of 210Po (2-15 Bq.kg-1). The daily dietary intakes of 210Po vary widely around the world with an estimated average median of about 160mBq.day-1. That corresponds to annual effective doses of about 70μSv.a-1 for 210Po. Populations mainly living on reindeer meat or marine food have a 5-10 fold higher annual effective doses. High activity concentrations (13 ± 3 Bq.kg-1) of Po-210 and Pb-210 are found in tobacco and its products. The annual effective radiation dose from 210Po for the whole body of a smoker who smokes 20 cigarettes per day has been estimated to 400μSv.a-1. The concentrations of 210Po in the air-ways and the lung tissues caused by smoking of tobacco contributes to a high radiation adsorbed dose to the respiratory epithelium, which contribute to the increased incidence of lung cancer observed among smokers, In December of 2006, former Russian intelligence operative Alexander Litvinenko died by what proved to be ingestion of polonium-210. This incident brought with it an increased interest of the bio-kinetics and radio-toxicity of 210Po. Alpha particles have a greater relative biological effectiveness (RBE) than gamma and X-rays considering cancer induction. But there are still no significant proofs in terms of increased risk in humans of in vivo bystander effects of 210Po alpha particle radiation. More work has to been done in studying RBE and the mechanism of the bystander effect and its relevance to cancer induction in man