Radiation Protection Regulations Research Articles

A National Survey: I. Performance of Medical Radiographic X-Ray Systems in Greece

This is the tirst of two papers on the assessment of medical conventional radiological X ray systems at the private sector in Greece. This paper presents the quality control results of radiographic X ray systems, while the quality control results of fluoroscopic X ray systems will be presented in a forthcoming paper. A total number of 387 privately owned (48% of the total installed in Greece) radiographic X ray facilities were surveyed during the period 1995 - 1997. Certain important radiographie parameters have been assessed according to a quality control protocol and the measured parameter values are compared to the relevant acceptance limits. The results show that the overall performance of the radiographic X ray systems is below optimal since only 36% of them have satisfactory performance in full compliance with the radiation protection regulations. The X ray systems installed recently, show better performance than those operating for some years. This can be attributed to the recent calibration and the performance of acceptance tests and quality control. Routine servicing as well as implementation of quality control on a regular basis will, it is believed, substantially improve the performance and reduce malfunctioning of the X ray systems.

A National Survey: II. Performance of Medical Fluoroscopic X-Ray Systems in Greece

The results from a survey in 297 (46 % of the total) fluoroscopie X ray facilities in the private sector in Greece are presented. Certain fluoroscopic parameters for under-table tube and remote control over-table tube fluoroscopic systems have been evaluated, according to a specific quality control protocol and compared with acceptance limits. The results show that the overall performance of the fluoroscopic systems is below optimal, since only 55.5% of the fluoroscopic systems performed satisfactorily and in compliance with the radiation protection regulations. Remote control over-table tube fluoroscopic systems had much better performance characteristics than under-table tube systems, with respect to patient dose and image quality. A system of routine servicing as well as implementation of quality control on a regular basis are believed substantially to reduce variation fron the normal performance and system malfunctioning.

The linear no-threshold dose-effect relation: is it relevant to radiation protection regulation?

Official radiogenic cancer risk estimates for low-dose, protracted exposure conditions have been based on linear, no-threshold downward extrapolation from medium and high-dose effects among a population of A-bomb survivors, with the application of a downward correction for an assumed reduced biological effectiveness at low doses and low dose rates (DDREF correction). Neither in the follow-up of populations exposed to the high-dose A-bomb flash, nor from epidemiological data after low-dose occupational or medical irradiation is there any convincing evidence for this DDREF hypothesis--even less for a zero-effect threshold dose. To the contrary, for external low-dose exposures of nuclear workers or general populations, cancer risks per unit dose have been found to be about 1 order of magnitude larger than those derived from the Japanese survivors, with larger discrepancies for persons above 50 years of age, and for x-rayed fetuses. This may be due to a dose and dose-rate effect exactly opposite from that postulated by the DDREF assumption, and a dose-dependent bias due to selection for exceptionally high immune competence among the > 5 years A-bomb survivor cohort. Excess cancer mortality following occupational exposures to ingested fission products and radiation-associated teratogenic, genetic, and cancer detriment among diverse populations who had ingested small amounts of radioactivity after the precipitation of fallout at great distances from the Chernobyl nuclear explosion, suggest discrepancies of as much as 2 orders of magnitude with official risk estimates. Contrary to widely publicized statements, claiming that current regulations of population exposures are far too restrictive, thus unnecessarily costly for the radiation industries, the aggregate of radiation epidemiological evidence suggests that current standards are inadequate to protect public health.

Auswirkung des Medizinproduktegesetzes (MPG) auf das Atomrecht

The regulations of the law for medical products have to be followed when medical products are put on the market or into service or when medical products are operated. On January, 1st, 1995 the law for medical products came into force, and the corresponding terms of the X-ray and radiation protection regulations were adapted. The present paper deals with the effects of the law for medical products upon the operators, manufacturers and suppliers of equipment subjected to the X-ray and radiation protection regulations. The impact upon the boards and the authorities as well as the experts is also discussed. Similar adaptions have been necessary in Austria since the Board's guidelines concerning medical products had to be included into national law, too. Switzerland, however, not being a member of the European Union, is not obliged to follow these regulations, although the essential proposals of these guidelines for medical products have also influenced the law in Switzerland.

ＩＣＲＰ ＩＣＲＰ勧告とわが国の法令

ＩＣＲＰ ＩＣＲＰ勧告とわが国の法令

Evaluation of ilmenite serpentine concrete and ordinary concrete as nuclear reactor shielding

The present study involves adapting a formal decision methodology to the selection of alternative nuclear reactor concretes shielding. Multiattribute utility theory is selected to accommodate decision makers' preferences. Multiattribute utility theory (MAU) is here employed to evaluate two appropriate nuclear reactor shielding concretes in terms of effectiveness to determine the optimal choice in order to meet the radiation protection regulations. These concretes are Ordinary concrete (O.C.) and Ilmenite Serpentile concrete (I.S.C.). These are normal weight concrete and heavy heat resistive concrete, respectively. The effectiveness objective of the nuclear reactor shielding is defined and structured into definite attributes and subattributes to evaluate the best alternative. Factors affecting the decision are dose received by reactor's workers, the material properties as well as cost of concrete shield. A computer program is employed to assist in performing utility analysis. Based upon data, the result shows the superiority of Ordinary concrete over Ilmenite Serpentine concrete.

Concept for Internal Dosimetry and Approval of Internal Dosimetry Services in Switzerland

The new Swiss radiation protection regulations will require approval of the internal dosimetry laboratories. The procedures allow for two types of bioassay measurements: The «screening measurements» for the local staff using relatively simple instrumentation to make sure that no unexpected intake has occurred and the «incorporation measurements» by a dosimetry service approved for internal dose assessment. The use of standard biokinetic models and retention functions is recommended as long as dose limits are not exceeded and it is assumed that the intake took place in the middle of the monitoring interval. Nuclide-specific data sheets give detailed guidance on monitoring methods, intervals, and dose calculation. Effective dose due to internal and external exposure of the radiation workers is recorded by the central dose registry

Technical note: a new afterloading applicator for primary brachytherapy of endometrial cancer.

Surgery is the treatment of choice for carcinoma of the endometrium. If the patient is not eligible for surgery because of advanced age or internal problems, primary irradiation—in most cases a combination of external beam radiation with brachytherapy—is indicated. In the following we present a new applicator used for intrauterine brachytherapy. In 1936 Heyman showed that the packing technique—which was later modified by Ries (1944), who introduced the so-called radium tamponade method, and by Becker and Scheer (1952)—was superior to the radium tandem method. This was documented by the 20–25% improvement in survival rates (Heyman et al, 1941). Radiation protection regulations have forced us to abandon the radium method in favour of the afterloading technique (Henschke, 1960; Waltstam, 1962). With the afterloading technique the results for cervical cancer are just as good as those of the radium method. Several afterloading methods have been described to treat cancer of the endometrium. However, to date there has been no satisfactory simulation (Simon et al, 1971; Rotte et al, 1973; Busch et al, 1977; Pernot, 1977; Bauer et al, 1981; Nori et al, 1982). Irradiation using a single applicator is only suitable for brachytherapy of small uteri. Radiation treatment using curved tubes to reach into the corners of the uterus results in a very inhomogenous dose distribution in the uterine mucosa, the tumour, and the target volume of the entire uterus.

Ein Überblick über die administrativen Aspekte der Qualitätssicherung in der Röntgendiagnostik

The aim of quality assurance in diagnostic radiology is to optimize image quality under the important boundary condition of the smallest possible exposure of the patient. One of the tasks of the „Röntgenverordnung”, the radiation protection regulation for medical radiology, is to convey this aim into practice. The regulation therefore requires all the operating institutions to arrange acceptance and constancy checks of their X-ray installations. The regulation also requires to install special institutions, the medical and dental boards („ärztliche Stellen”), which have been entitled to give advice along with the conduction of quality assurance. Medical staff not always reaffirm the performance of quality assurance. It is plausible to conjecture that difficulties of mutual understanding or misinterpretations at the administrative level could be involved. The present paper aims at some clearing up under these aspects.

Determination of Low Activities Released by a Decommissioned Fuel Fabrication Plant Through Natural Air Exchange

A method to determine the release of low activities through natural air exchange from a decommissioned fuel fabrication plant is described. The method has been applied to the buildings of the NUKEM-A plant and was important in obtaining governmental authorization for the plant decommissioning. The air exchange rate in the NUKEM-A plant was measured by using a tracer gas method. For that purpose, N2O as inert gas was injected into representative rooms, and the decrease of concentration caused by exfiltration processes was measured by an infrared gas analyzer as a function of time. The knowledge of this decay curve allows the calculation of low activities, which may be released into the environment by the natural air exchange. The activity is determined according to the German radiation protection regulation. From this, an air exchange rate of ∼25 h−1 would be equivalent to 10% of the tolerable activity emission. The measured exchange rates are less than ∼0.5 h−1. This results—at least for the meteorological conditions during the measurement period—in a significantly lower activity release than that permitted. The measuring method was successfully performed and can be recommended for similar investigations.

Chapter 6: Radiation Protection Regulations

The basis for the radiation protection regulations that apply to the transport of radioactive materials are the Atomic Energy Act related provisions in the Radiation Protection Ordinance (StrlSchV) and the provisions of the Directives on the Transport of Hazardous Goods. The applicability of the Radiation Protection Ordinance is, however, limited as the provisions of §§ 29 to 80 do not apply to the transport of radioactive materials according to current legislation, with the exception of the principles of radiation protection contained in § 28 (e.g. minimisation principle).

Past and revised risk estimates for cancer induced by irradiation and their influence on dose limits

The present is a time of great change in the assessment of radiation risk and its influence on dose limits. The main sources of risk estimates arise from irradiation for medical reasons and from the use of atomic weapons. The effects of radiation on humans and animals are reviewed by such august bodies as the International Commission on Radiological Protection (ICRP), the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and the Biological Effects of Ionizing Radiation (BEIR) Committee in the USA. Over the years they have developed many of the concepts that give structure to the science of limiting radiation-induced cancers and other harmful effects. These concepts are mentioned here for completeness and because they also provide relative stability in a time of change. Central in its importance on radiation risk estimates is the analysis of excess cancer risks of the Japanese bomb survivors which was based on a dosimetry system (T65DR) devised in 1965. Reassessment commenced in the early 1970s, with a new dosimetry system employed in the extended study of the Nagasaki and Hiroshima populations in 1985. The considerable debate that the new “DS86” dosimetry of the Japanese Life Span Study has caused reminds us again of the key position of this Japanese population in influencing radiation risk estimates and protection regulations.

Policy and Technical Matters for the Application of ICRP 1977 Recommendations to Japanese Radiation Protection Regulations

Policy and Technical Matters for the Application of ICRP 1977 Recommendations to Japanese Radiation Protection Regulations

An evaluation of the external radiation exposure dosimetry and calculation of maximum permissible concentration values for airborne materials containing 18F, 15O, 13N, 11C and 133Xe.

To better understand the dose equivalent (D.E.) rates produced by airborne releases of gaseous positron-emitting radionuclides under various conditions of cloud size, a study of the external radiation exposure dosimetry of these radionuclides, as well as negatron, gamma and x-ray emitting 133Xe, was undertaken. This included a calculation of the contributions to D.E. as a function of cloud radii, at tissue depths of 0.07 mm (skin), 3 mm (lens of eye) and 10 mm (whole body) from both the particulate and photon radiations emitted by these radionuclides. Estimates of maximum permissible concentration (MPC) values were also calculated based on the calculated D.E. rates and current regulations for personnel radiation protection (CFR84). Three continuous air monitors, designed for use with 133Xe, were evaluated for applications in monitoring air concentrations of the selected positron emitters. The results indicate that for a given radionuclide and for a cloud greater than a certain radius, personnel radiation dosimeters must respond acceptably to only the photon radiations emitted by the radionuclide to provide acceptable personnel dosimetry. For clouds under that radius, personnel radiation dosimeters must also respond acceptably to the positron or negatron radiations to provide acceptable personnel dosimetry. It was found that two out of the three air concentration monitors may be useful for monitoring air concentrations of the selected positron emitters.

On Some Symmetries That May Influence Radiation Protection Regulations

The International Commission on Radiation Units and Measurements (ICRU) recommended a 30-cm-diameter sphere of a specific tissue-equivalent composition as a regulatory standard for specification of ambient radiation levels 13 years ago. In spite of this, the ICRP-defined permissible fluence limits for neutrons and photons derived from depth-dose calculations in cylindrical or slab phantoms are still in common use. This is probably why so much effort has recently been devoted to radiation transport and energy deposition calculations in the ICRU sphere. In all these studies, the three-dimensional (3-D) Monte Carlo approach was applied, resulting in enormously long CPU times and in high statistical uncertainties information. The author proposes the 1-D approach whereby the obvious symmetries of spherical geometry and of radiation transport itself are used.

New regulations for old (radiation protection)

British radiation protection will have new regulations: these cannot be in force before 1985 however. The author reviews regulations over the past 40 years. The topics discussed include: ICRP recommendations; the Protection against Ionising Radiations Committee of the Medical Research Council (1950); the Ministry of Labour's thoughts on radiation protection regulations (1940); the Health and Safety at Work Act (1974).

Specific Activity Estimation of Minerals and Other Materials Containing Natural Radionuclides

Most radiation protection regulations and codes define limits on gross specific activity below which radiation protection measures are not required. The question arises as to which radionuclides contained in a sample have to be taken into account in calculating the gross activity. This paper considers natural radionuclides according to their radiotoxicity and relative dose contributions and suggests criteria against which radiological relevance can be judged. Several examples of naturally occurring materials are discussed.

Exposure to radiation in percutaneous cervical cordotomy (author's transl)

During eleven high cervical percutaneous cordotomies using the image intensifier, the amount of exposure to X-radiation was measured at various sites on both the patient and the operator. The values lay below the maximum doses allowed by the radiation protection regulations (Röv; section 33. Para 1).

Radiation Protection Regulations in Various Countries (III)

Radiation Protection Regulations in Various Countries (III)

Radiation protection regulations in various countries (IV) (author's transl)

Radiation protection regulations in various countries (IV) (author's transl)