[en] When measuring absolute neutron flux-spectra, thin detector foils are irradiated in a neutron field. The absolute activity of isotopes generated by activation or fission reactions (fission products) is then measured, using an efficiency calibrated high resolution gamma-ray spectroscopy system, and the absolute reaction rates for their production is determined. Finally the flux-spectrum is determined based upon the reaction rate values. A general method to obtain flux-spectra from the reaction rate is the unfolding method. The above process involves computations of photopeak area, reaction rate, flux perturbation corrections and flux-spectrum. The PC's are well suited for the data processing system outlined above. Using available interfaces, the PC's can be involved even in the data acquisition. Graphical facilities allow decision upon the data processing flow

[en] The aim of the study was to assess the risk to the personnel and neighbouring patients exposed to ionizing radiation during their stay at the Isotopic Therapy Clinic in Warsaw where therapeutic applications of I-131 are routinely performed. To this end, thermoluminescent dosimeters were deposited in various places throughout the Clinical ward and the absorbed doses were read after 125 days of the exposition. Additionally, exposure dose rates were determined at the skin surface over the thyroid gland at 0.5 and 1.0 m away from 71 patients treated with I-131 for hyperthyroidism or thyroid cancer (as a supplementary therapy after thyroidectomy) and the potential dose equivalents were calculated. From these values ''restriction times'', i.e., the amounts of time needed for the potential dose equivalents to decline below the limit recommended for occupational or public exposures to ionizing radiation were derived. The results indicate that - a) the probability to exceed the recommended annual dose limit by the personnel (50 mSv y^-1) and neighbouring patients not subjected to radiotherapy (1 mSv y^-1) during their exposition at the Isotopic Therapy Clinic to the I-131 treated patients is practically equal to zero; b) no restrictions in terms of limiting the duration of contact with the I-131-treated patients are necessary during the occupational exposures of the personnel of the Clinic; and c) the treated patients may incur some risk to the general public only when injected with high doses of I-131 and/or only within about 3 days upon the application of the radionuclide. (author)

[en] The LNT-theory of cancer generation by ionizing radiation is commonly vindicated by 3 arguments: The stochastic character of irradiation hits to cells, the monoclonality of cancer generation, and the error proneness of DNA-repair. It is shown that this conclusion is logically inadmissible. Equally, the rescuing attempts tried by some LNT-supporters are not successful. It contradicts the laws of thinking to exclude threshold and hormesis in this way. (author)

[en] So far, the chromosomal studies are the most established method of biological dosimetry. We compared this method with micronucleus and apoptosis detection method simultaneously in V-79 cells. The frequency of apoptotic cells in low doses (0.1-0.5Gy) are more prominent than two other methods in Vitro. Presumably, apoptosis may be chosen as a preferable alternative biological dosimetry or environmental assessment of biological effects of ionizing radiation. (author)

[en] The Philippine Nuclear Research Institute (PNRI) initiated various nuclear regulatory conferences with its licensees in the years 1995 and 1996. The purpose of these conferences was mainly to reach a common understanding of the provisions of the Code of PNRI Regulations (CPR) and foster openness between PNRI and licensees. Each conference was designed for a specific category of licensees, i.e., commercial, medical, industrial (nuclear gauges), industrial radiography, research and teaching. The regulatory group of PNRI discussed the applicable regulations to each category of licensees including experiences in implementation and enforcement. This was followed by licensees' feedback on experiences in dealing with the regulatory group and complying with applicable regulations. The outcome of these conferences brought out generic and specific issues and concerns. Majority of the general issues and concerns were directed towards PNRI. This brought to the realization that although safety is the primary responsibility of the licensee, PNRI as the only competent authority on radioactive material and radiation safety matters, carries the bigger share of preparing the licensees for this kind of responsibility. (author)

[en] Before 1974 about 5000 children were irradiated at the Institut Gustave-Roussy for a skin hemangioma of whom 20% were treated with radium applicators. To evaluate the absorbed doses to these patients at any site, we have developed a software program which permits simulation of the actual patient and treatment conditions. Part of this software is devoted to constructing an Individual Computerized Tomography Anatomy (ICTA) based on real human transverse slices and auxological tables. From the generated phantom, 160 anatomical sites of epidemiological interest are defined and localized according to a Cartesian co-ordinate system. The gamma doses at all sites from Ra-226 applicators are calculated by an algorithm which permits separation of the radiation paths in air, tissue, and lungs. It includes a correction for attenuation and scatters in infinite and semi-infinite mediums. To evaluate the factor φ(r) for these corrections at any distance or position from the applicator, we have modelled the results from several Monte Carlo simulations. In the range of 1 to 10 cm, the φ(r) values obtained from our model showed good agreement with those obtained by published methods. For several cases, the absorbed doses at points in water and patients from radium applicators estimated by this software, were compared to those measured and estimated at the Karolinska Hospital. The results showed good agreement. (author)

[en] In 1990, the International Commission on Radiological Protection recommended the introduction of a supplementary dose limit for pregnant staff so that the foetus was adequately protected. This dose limit was framed in terms of an abdomen surface dose of 2 mSv for the duration of the pregnancy, once it had been declared. The philosophical basis underlying this supplementary dose limit was the desire to treat the foetus as a member of the public in respect of the occupational exposure of the mother. In the Basic Safety Standards, the International Atomic Energy Agency endorsed the need to limit the foetal dose, but in this document the dose limit refers to the foetus. The introduction of dose limits for foetal exposure to radiation has significant implications for hospitals as many workers are women of child bearing age. The practical implications of this dose limit will be discussed as well as suggested monitoring arrangements. (author)

[en] Radiation background in Tbilisi City has been studied; collective and annual average statistic dozes have been ascertained, parameters of stochastic effects' (cancerogenic, genetic) risks caused by low dozes of ionizing radiation have been calculated. From 21 cases of total risk 7 are stipulated by genetic defects, 14 - by lethal malignant tumor. The conclusion is that we should not expect important changes in health condition of population caused by existing in Tbilisi City radiation background. (author)

[en] In Tanzania, the radiation protection law was issued in 1983. Under this law, the National Radiation Commission is responsible for safe uses of ionizing radiation. The regulatory control of the resulting doses from the uses of radiation sources in medicine, industry, research and teaching is presented. The system of control reflects the existing interactions between the National Radiation Commission and users through the established radiation protection infrastructure. From the national dose registry data, it is found that the highest annual individual doses over 10 years ago, came from less than 5% of total monitored workers and were in the range 10 - 15 mSv y^-1. The experienced radiation levels in uncontrolled areas of potential workplaces is less than 1 μSv h^-1. The possibility for associating such low dose levels to the effectiveness of the existing regulatory dose control framework is discussed. Despite of this achievement, the need to improve further the radiation protection and safety programs is found necessary. (author)

[en] The study of adaptive possibilities and cancer risk in animals exposed at low doses of ionizing radiation was the object of the present work. The action of immunostimulating treatment on these processes was studied as well. In previously irradiated animals the diminution of adaptive possibilities and of the antitumoral resistance of the organism was observed. The stimulating action of Bufostimulin on these processes in irradiated animals was less pronounced than in unirradiated ones. (author)