Aim. The aim of this work was to assess the doses received by a diver exposed to a radiation source during maintenance work in the fuel transfer pool at a Swiss nuclear power plant, and to define whether the statutory limit was breached or not. Method. Onsite measurements were carried out and different scenarios were simulated using the MicroShield Software and the MCNPX Monte Carlo radiation transport code to estimate the activity of the irradiating object as well as the doses to the limbs and the effective dose delivered to the operator. Results. The activity of the object was estimated to 1.8 TBq. From the various dose estimations, a conservative value of 7.5 Sv was proposed for the equivalent dose to the skin on the hands and an effective dose of 28 mSv. Conclusion. The use of different experimental and calculation methods allowed us to accurately estimate the activity of the object and the dose delivered to the diver, useful information for making a decision on the most appropriate scheme of follow up for the patient.

In 2013, a nationwide investigation was conducted in Switzerland to establish the population's exposure from medical X rays. A hybrid approach was used combining the Raddose database accessible on-line by the participating practices and the Swiss medical tariffication system for hospitals. This study revealed that the average annual number of examinations is 1.2 per inhabitant, and the associated annual effective dose is 1.4 mSv. It also showed that computed tomography is the most irradiating modality and that it delivers 70 % of the total dose. The annual effective dose per inhabitant registered a 17 % increase in 5 y and is comparable with what was recently reported in neighbouring countries.

Whole-body counting is a technique of choice for assessing the intake of gamma-emitting radionuclides. An appropriate calibration is necessary, which is done either by experimental measurement or by Monte Carlo (MC) calculation. The aim of this work was to validate a MC model for calibrating whole-body counters (WBCs) by comparing the results of computations with measurements performed on an anthropomorphic phantom and to investigate the effect of a change in phantom's position on the WBC counting sensitivity. GEANT MC code was used for the calculations, and an IGOR phantom loaded with several types of radionuclides was used for the experimental measurements. The results show a reasonable agreement between measurements and MC computation. A 1-cm error in phantom positioning changes the activity estimation by >2%. Considering that a 5-cm deviation of the positioning of the phantom may occur in a realistic counting scenario, this implies that the uncertainty of the activity measured by a WBC is ∼10-20%.

Background The frequency of CT procedures has registered a significant increase over the last decade, which led at the international level to an increasing concern on the radiological risk associated with the use of CT especially in paediatrics. This work aimed at investigating the use of computed tomography in Switzerland, following the evolution of CT frequency and dose data over a decade and comparing it to data reported in other countries. Methods The frequency and dose data related to CT are obtained by means of a nationwide survey. National frequencies were established by projecting the collected data, using the ratio of the number of CT units belonging to the respondents to the total number of CT units in the country. The effective doses per examination were collected during an auditing campaign. Results In 2008 about 0.8 Million CT procedures (~ 100 CT examinations / 1000 population) were performed in the country, leading to a collective effective dose of more than 6000 man.Sv (0.8 mSv/caput). In a decade the frequency of CT examinations averaged over the population and the associated average effective dose per caput increased by a factor of 2.2 and 2.9 respectively. Conclusions Although the contribution of CT to the total medical X-rays is 6% in terms of the frequency, it represents 68% in terms of the collective effective dose. These results are comparable to those reported in a number of countries in Europe and America with similar health level.

Nationwide surveys on radiation dose to the population from medical radiology are recommended in order to follow the trends in population exposure and ensure radiation protection. The last survey in Switzerland was conducted in 1998, and the annual effective dose from medical radiology was estimated to be 1 mSv y(-1) per capita. The purpose of this work was to follow the trends in diagnostic radiology between 1998 and 2008 in Switzerland and determine the contribution of different modalities and types of examinations to the collective effective dose from medical x-rays. For this reason, an online database (www.raddose.ch) was developed. All healthcare providers who hold a license to run an x-ray unit in the country were invited to participate in the survey. More than 225 examinations, covering eight radiological modalities, were included in the survey. The average effective dose for each examination was reassessed. Data from about 3,500 users were collected (42% response rate). The survey showed that the annual effective dose was 1.2 mSv/capita in 2008. The most frequent examinations are conventional and dental radiographies (88%). The contribution of computed tomography was only 6% in terms of examination frequency but 68% in terms of effective dose. The comparison with other countries showed that the effective dose per capita in Switzerland was in the same range as in other countries with similar healthcare systems, although the annual number of examinations performed in Switzerland was higher. Health Phys. 102(3): 263-270; 2012

Radiological imaging used in cardiac procedures may result in significant radiation doses to the patient. The aim of this study was to estimate radiation risks from typical cardiac procedures. Monte Carlo simulations were performed to assess absorbed organ doses. Equivalent organ doses and effective doses were calculated using the recommendations in ICRP Publications 60 and 103 [1,2]. The differences in effective dose applying the two recommendations were found to be small. Cancer incidence risks for different organs were calculated for different sex and age at exposure using the lifetime attributable risks provided by the Biological Effects of Ionizing Radiations report VII. These results are a straightforward method to comprehend radiation risks.

In population surveys of the exposure to medical X-rays both the frequency of examinations and the effective dose per examination are required. The use of the Swiss medical tariffication system (TARMED) for establishing the frequency of X-ray medical examinations was explored. The method was tested for radiography examinations performed in 2008 at the Lausanne University Hospital. The annual numbers of radiographies determined from the "TARMED" database are in good agreement with the figures extracted from the local RIS (Radiology Information System). The "TARMED" is a reliable and fast method for establishing the frequency of radiography examination, if we respect the context in which the "TARMED" code is used. In addition, this billing context provides most valuable information on the average number of radiographs per examination as well as the age and sex distributions. Radiographies represent the major part of X-ray examinations and are performed by about 4,000 practices and hospitals in Switzerland. Therefore this method has the potential to drastically simplify the organisation of nationwide surveys. There are still some difficulties to overcome if the method is to be used to assess the frequency of computed tomography or fluoroscopy examinations; procedures that deliver most of the radiation dose to the population. This is due to the poor specificity of "TARMED" codes concerning these modalities. However, the use of CT and fluoroscopy installations is easier to monitor using conventional survey methods since there are fewer centres. Ways to overcome the "TARMED" limitations for these two modalities are still being explored.

The aim of this study was to investigate the radiation exposure of the Swiss population to interventional procedures. A nationwide survey was conducted in Switzerland. The annual effective dose per capita due to interventional procedures was found to be 0.14 mSv, corresponding to 12% of the total dose. Coronary angiography and percutaneous coronary interventions were found to be the most frequent and the most irradiating interventional procedures, accounting for 52% of the total examination frequency and 64% of the dose delivered to the population. Switzerland stands at the same level as other countries in terms of effective dose per capita due to interventional radiology.

The volume of diagnostic or therapeutic procedures in cardiology that require the use of ionizing radiation is increasing constantly. Currently, technological developments offer the possibility of exploring not only the cardiac function (measurement of ejection fraction, for example) but also the state of coronary and great vessels. In fact, the management of patients with heart disease often requires the use of investigative techniques using X-rays. For example 3.85 million cardiac catheterizations were performed in the United States in 2002 (Einstein et al., 2007). In Switzerland the last national survey on the exposure of the population by medical radiology revealed that nearly 34 000 coronary angiographies and more than 18 000 coronary dilatations were performed in 2008. They are associated to 65% of the collective dose related to interventional radiology and 8% to that related to all medical X-rays (Samara et al. 2011). The increase in radiological examinations using ionizing radiation has been mentioned for several years not only in medical journals for professionals but also in the press addressing the general public. For example, in its edition of 17 June, 2007, the New York Times questioned the public opinion about the justification of the increasing number of CT examinations. While most examinations deliver relatively low doses and thus add only a low risk to the procedure itself, there are situations where doses exceed the dose level where an excess risk of death from cancer has been demonstrated. In addition, some complex procedures may result in the occurrence of deterministic effects such as burns to the skin. The substantial increase of fluoroscopy-guided procedures in cardiology over the past few years has been accompanied by a parallel growth in concern for patient radiation safety and for the safety of the operators who perform these procedures. Thus, radiation safety has become a major issue in radiology departments. The aim of this chapter is: to recall the effects of ionizing radiation on the human body and the radiological risks; to introduce the dosimetric quantities (basic and operational) commonly used to quantify those risks; to briefly present the principles of radiation protection; to provide the tools (actions and means) necessary for operational radiation protection.

A wide variation in patient exposure has been observed in interventional radiology and cardiology. The purpose of this study was to investigate the patient dose from fluoroscopy-guided procedures performed in non-academic centres when compared with academic centres. Four procedures (coronary angiography, percutaneous coronary intervention, angiography of the lower limbs and percutaneous transluminal angioplasty of the lower limbs) were evaluated. Data on the dose area product, fluoroscopy time and number of images for 1000 procedures were obtained from 23 non-academic centres and compared with data from 5 academic centres. No differences were found for cardiology procedures performed in non-academic centres versus academic ones. However, significantly lower doses were delivered to patients for procedures of the lower limbs when they were performed in non-academic centres. This may be due to more complex procedures performed in the academic centres. Comparison between the centres showed a great variation in the patient dose for these lower limb procedures.

Diagnostic reference levels (DRLs) were established for 21 indication-based CT examinations for adults in Switzerland. One hundred and seventy-nine of 225 computed tomography (CT) scanners operated in hospitals and private radiology institutes were audited on-site and patient doses were collected. For each CT scanner, a correction factor was calculated expressing the deviation of the measured weighted computed tomography dose index (CTDI) to the nominal weighted CTDI as displayed on the workstation. Patient doses were corrected by this factor providing a realistic basis for establishing national DRLs. Results showed large variations in doses between different radiology departments in Switzerland, especially for examinations of the petrous bone, pelvis, lower limbs and heart. This indicates that the concept of DRLs has not yet been correctly applied for CT examinations in clinical routine. A close collaboration of all stakeholders is mandatory to assure an effective radiation protection of patients. On-site audits will be intensified to further establish the concept of DRLs in Switzerland.

The number of fluoroscopy-guided procedures in cardiology is increasing over time and it is appropriate to wonder whether technological progress or change of techniques is influencing patient exposure. The aim of this study is to examine whether patient dose has been decreasing over the years. Patient dose data of more than 7700 procedures were collected from two cardiology centres. A steady increase in the patient dose over the years was observed in both the centres for the two cardiological procedures included in this study. Significant increase in dose was also observed after the installation of a flat-panel detector. The increasing use of radial access may lead to an increase in the patient exposure. The monitoring of dose data over time showed a considerable increase in the patient exposure over time. Actions have to be taken towards dose reduction in both the centres.

The aim of this work is to compare two methods used for determining the proper shielding of computed tomography (CT) rooms while considering recent technological advances in CT scanners. The approaches of the German Institute for Standardisation and the US National Council on Radiation Protection and Measurements were compared and a series of radiation measurements were performed in several CT rooms at the Lausanne University Hospital. The following three-step procedure is proposed for assuring sufficient shielding of rooms hosting new CT units with spiral mode acquisition and various X-ray beam collimation widths: (1) calculate the ambient equivalent dose for a representative average weekly dose length product at the position where shielding is required; (2) from the maximum permissible weekly dose at the location of interest, calculate the transmission factor F that must be taken to ensure proper shielding and (3) convert the transmission factor into a thickness of lead shielding. A similar approach could be adopted to use when designing shielding for fluoroscopy rooms, where the basic quantity would be the dose area product instead of the load of current (milliampere-minute).

Over the past few years the frequency of computed tomography (CT) examinations has dramatically increased. Simultaneously, there has been also a significant increase in CT patient dose due to high-resolution imaging and application of more complex scan techniques. Since no dose limit exists for patients, the International Commission on Radiological Protection introduced the concept of diagnostic reference levels (DRL) as a means of dose optimization. The aim of this project is to collect patient doses for the most frequently applied CT protocols and to provide a realistic basis for establishing DRL in CT in Switzerland. Starting in 2007, patient doses of every Swiss radiological institute operating a CT scanner were going to be collected. Volume computed tomography dose index (CTDIvol) and dose-length product (DLP) for standard patients was collected for selected clinical CT protocols. The 75th percentile of the CTDIvol and DLP distribution was calculated and compared to the proposed DRL which is partly based on the Swiss survey in 1998 and recommendations of the European Union. For standard examination of the skull/brain the 75th percentiles are higher than the proposed DRL (72 mGy vs. 60 mGy; 1180 mGy∙cm vs. 1000 mGy∙cm). For examination of thorax and abdomen/pelvis the 75th percentiles are close to the proposed DRL (thorax: 15 mGy vs. 15 mGy; 511 mGy∙cm vs. 450 mGy∙cm; abdomen/ pelvis: 16 mGy vs. 15 mGy; 701 mGy∙cm vs. 700 mGy∙cm). In conclusion, there is always a trade-off between dose reduction and diagnostic image quality. However, especially for skull/brain examinations, optimization is still feasible. The concept of DRL provides a valuable means for practitioners and manufacturers in optimizing CT protocols.

The purpose of this paper is to present a strategy to define diagnostic reference levels DRL for fluoroscopic, dose-intensive examinations in cardiology and interventional radiology. This work is part of the project of the Federal Office of Public Health of Switzerland to translate the guidelines of the ICRP and the EU into action. After the 2002 survey in all University Hospitals in Switzerland this work will present the results of the 2006-2007 survey performed in small and medium sized hospitals. The data of the small and medium sized hospitals are analyzed to establish DRL. They are corrected to patient size and analyzed in respect to the difficulty of the examination, the experience of the operator and the type of image detection system. The results of the study will be compared to those of the former study in the University Hospitals.

Surveying the frequency of medical x-ray examinations is of prime importance in the assessment of the collective detriment due to diagnostic and interventional radiology. In the past, this was performed using paper questionnaires, but today there is an increasing interest in the automatic collection of the frequency data for reasons related to reducing the work load and increasing the accuracy of the results. This paper present the work performed in Switzerland to explore the use of the Tarmed coding system for this purpose. The preliminary investigation covering a sample of examinations indicates that Tarmed coding can easily be used for the collection of radiography and CT examinations, but presents some difficulties for fluoroscopy, mainly in the case of complex angiography and interventional examinations.

Ziele: Bei der Bewertung von Daten zu Häufigkeit und Dosis strahlendiagnostischer Maßnahmen ist ein internationaler Vergleich unerlässlich. Dieser ist jedoch schwierig, da aufgrund der unterschiedlichen Gesundheitssysteme die Auswertungsschemata in den verschiedenen Ländern sehr verschieden und zum Teil auch nicht hinreichend transparent sind. Um diesbezüglich die Datenlage auf europäischer Ebene zu verbessern, wurde im Jahre 2004 die europäische Arbeitsgruppe DOSE DATAMED gegründet. Methode: Die Methoden zur Datenerfassung und -auswertung der teilnehmenden Länder (Vereinigtes Königreich, Belgien, Dänemark, Deutschland, Frankreich, Luxemburg, Niederlande, Norwegen, Schweden, Schweiz) sowie die Ergebnisse bezüglich Häufigkeit von strahlendiagnostischen Maßnahmen, Dosis pro Untersuchung und kollektiver effektiver Dosis wurden erfasst und gegenübergestellt. Der Vergleich beinhaltete auch mögliche Einflussfaktoren wie z.B. Gesundheitssysteme. Ergebnis: Computertomographien, Angiographien und Interventionen tragen in allen DOSE DATAMED Ländern den größten Teil zur kollektiven effektiven Dosis (S) bei. Für alle Röntgenuntersuchungen zusammengenommen unterscheiden sich die Länder bezüglich der Häufigkeit max. um den Faktor 2,5 (Min: 0,7; Max: 1,8 Unters. pro Einw. pro Jahr) und bezüglich S max. um den Faktor 4,5 (Min: 0,4; Max: 1,8 mSv pro Einw. pro Jahr) mit den höchsten Schätzwerten für Belgien, Deutschland und Luxemburg und den niedrigsten für Dänemark, die Niederlande und das Vereinigte Königreich. Schlussfolgerung: Die zum Teil beträchtlichen Unterschiede bei der Häufigkeit von Röntgenuntersuchungen und der zugehörigen kollektiven effektiven Dosis, die in den zehn Ländern beobachtet wurden, wurden von der DOSE DATAMED Gruppe als real eingeschätzt. Die Unterschiede sind sehr viel größer als die statistischen Unsicherheiten, die unvermeidbar mit der Datenerhebung und -analyse einhergehen. Die Unterschiede können zum großen Teil auf die verschiedenartigen Gesundheitssysteme der betrachten Länder zurückgeführt werden.

This document gathers the slides of the available presentations given during this conference. Sixty six presentations out of 68 are assembled in the document. The conference is organized in 11 sessions dealing with: 1 - radioprotection regulations and standards; 2 - radioprotection of patients; 3 - radiation effects on man and ecosystems; 4 - advances in dosimetry and metrology; occupational radioprotection (2 sessions); 5 - radioprotection of populations and ecosystems (2 sessions); 6 - radioprotection in incident, accident and post-accident situations; 7 - radioprotection and society