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The aim of this study was to investigate the effectiveness of different shielding materials in protective clothing using dicentric frequency in human peripheral lymphocytes as a marker of radiation-induced damage. Blood samples from a healthy donor were exposed to 70 kV x-rays behind shielding materials lead (Pb), tin/antimony (Sn + Sb) and bismuth barrier/tin/tungsten (Bi + Sn + W) with the same nominal lead equivalent value of 0.35 mm lead. Irradiation was performed either in contact (exposure position A, containing secondary radiation) or at a distance of 19 cm behind the shielding materials (exposure position B, containing only the unaffected transmitted photons). Using shielding material Sn + Sb, a significantly higher dicentric yield was determined at exposure position A relative to position B, whereas no significant differences were found between the exposure positions using shielding materials Pb or Bi + Sn + W. For doses up to 434.4 mGy at exposure position A, the slopes of the linear dose-response curves for dicentrics obtained behind shielding materials Pb and Bi + Sn + W were not significantly different, whereas a significantly higher slope was determined behind Sn + Sb relative to Pb and Bi + Sn + W. Using moderately filtered 220 kV x-rays as a reference, maximum RBE values at low doses (RBE(M)) of 1.22 ± 0.10, 2.28 ± 0.19 and 1.03 ± 0.12 were estimated immediately behind shielding materials Pb, Sn + Sb and Bi + Sn + W, respectively. These findings indicate a significantly higher RBE(M) of 70 kV x-rays behind shielding material Sn + Sb with respect to Pb or Bi + Sn + W. Using previous dicentric data obtained for exposure of blood from the same donor to x-rays at energies lower than 70 kV, it can be assumed that the increased RBE(M) of the broad spectrum of 70 kV x-rays (mean energy of 44.1 keV) may be attributed predominately to secondary (mainly fluorescence) radiation generated in the shielding material Sn + Sb that is able to leave the shielding material. Even if it is uncertain whether the marked dependency of the RBE at low doses on photon energy for chromosome aberrations is also representative for late radiation effects in healthy subjects, it should be taken into account that several prospective cohort studies have shown positive associations between higher chromosome aberrations in lymphocytes of healthy subjects and increased cancer incidence. Thus, it can be concluded that any additional biological damage by radiation exposure of healthy subjects, e.g. by using certain non-lead based shielding materials of protective clothing, should be avoided.

This paper presents the results of the 4th International Comparison of in vitro electron paramagnetic resonance dosimetry with tooth enamel, where the performance parameters of tooth enamel dosimetry methods were compared among sixteen laboratories from all over the world. The participating laboratories were asked to determine a calibration curve with a set of tooth enamel powder samples provided by the organizers. Nine molar teeth extracted following medical indication from German donors and collected between 1997 and 2007 were prepared and irradiated at the Helmholtz Zentrum Munchen. Five out of six samples were irradiated at 0.1, 0.2, 0.5, 1.0 and 1.5 Gy air kerma; and one unirradiated sample was kept as control. The doses delivered to the individual samples were unknown to the participants, who were asked to measure each sample nine times, and to report the EPR signal response, the mass of aliquots measured, and the parameters of EPR signal acquisition and signal evaluation. Critical dose and detection limit were calculated by the organizers on the basis of the calibration-curve parameters obtained at every laboratory. For calibration curves obtained by measuring every calibration sample three times, the mean value of the detection limit was 205 mGy, ranging from 56 to 649 mGy. The participants were also invited to provide the signal response and the nominal dose of their current dose calibration curve (wherever available), the critical dose and detection limit of which were also calculated by the organizers.

Seit 2007 gehort in Niedersachsen die Intensivverlegung zu den Aufgaben des Rettungsdienstes. Vor diesem Hintergrund hat sich die Arbeitsgemeinschaft Evaluation Intensivverlegung (AGEIV) gebildet. Durch sie wurden einheitliche Kriterien fur die Anforderungen von Intensivtransportmitteln definiert und ein landesweites Monitoring fur Intensivverlegungen eingefuhrt, um zu analysieren, ob die parallel vorgehaltenen Systeme [Intensivtransporthubschrauber (ITH) und Intensivtransportwagen (ITW)] bedarfsgerecht und effizient eingesetzt werden konnen. Es wurde eine prospektive Verlaufsbeobachtung und Evaluation der Intensivverlegungen in Niedersachsen vom 01.04.2008 bis zum 31.07.2010 durchgefuhrt. Insgesamt wurden 6779 Datensatze ausgewertet. Bei 4941 Einsatzen (72,9%) lag der Zielort in Niedersachsen. Durch Rettungshubschrauber (RTH)/ITH wurden 2928 Einsatze (43,2%) und 3851 Einsatze (56,8%) durch ITW durchgefuhrt. Im Mittel dauerte ein Einsatz 3 h 59 min±2 h 25 min, bodengebunden 4 h 39 min±2 h 23 min und luftgebunden 2 h 21 min±30 min. Alle Systeme erwiesen sich fur den Intensivtransport als geeignet. Bei 94,8% der bewerteten Einsatze war die Dringlichkeit zutreffend eingeschatzt; es waren 58,0% der Verlegungen nichtdisponibel. Von den Patienten wurden 76,8% in Kliniken hoherer Versorgungsstufe verlegt. Zur Intensivtherapie wurden 51,7% der Patienten und 40,4% zur Operation/Intervention verlegt. Es waren 38,2% der Patienten beatmet, und bei 48,3% wurde ein invasives Monitoring durchgefuhrt. Mit einer begrenzten Zahl von Intensivtransportsystemen, die parallel vorgehalten werden, ist es moglich, Intensivverlegungen bedarfsgerecht durchzufuhren, wenn der Einsatz der Rettungsmittel durch eine einheitliche Disposition effektiv und im Sinne der Aufgabenstellung erfolgt. Das kontinuierliche Monitoring mit fruhzeitigem Feedback an die Leistungserbringer hilft, zeitnah Korrekturmasnahmen bei Abweichungen vom gewunschten Ziel einzuleiten.

Hintergrund Die praklinische Sicherung der Atemwege stellt besondere Anspruche an das notfallmedizinische Personal. Spezifische Daten uber die individuelle Qualifikation der Notarzte (NA) und die Ausstattung der Rettungsmittel in der Region Norddeutschland liegen bisher nicht vor.

The RADIUS (Radiological Imaging Unification Strategy) project addresses the assessment of image quality in terms of both physical and clinically relevant measures. The aim is to unify our understanding of both types of measure as well as the numerous underlying factors that play a key role in the assessments of imaging performance. In this way it is expected to provide a solid basis for the improvement in radiological safety management, where not only radiation risks are considered but also diagnostic risks of incorrect clinical outcomes (i.e. false positive/false negative). The project has applied a variety of relevant experimental and theoretical methods to this problem, which is generic to medical imaging as a whole. Digital radiography of the chest and the breast has been employed as the clinical imaging domain vehicles for the study. The project addressed the problem from the following directions: role and relevance of pathology, human observer studies including receiver operating characteristics, image quality criteria analysis, structural noise analysis, physical measurements on clinical images, physical measurements on imaging system, modelling of imaging system, modelling of visual processes, modelling of doses delivered and IT-based scientific support strategies. This paper presents an overview of the main outcomes from this project and highlights how the research outcomes actually apply to the real world. In particular, attention will be focused on new and original findings and methods and techniques that have been developed within the framework of the project. The relevance of the project's outcomes to future European research will also be presented.

Purpose Currently, lead-free x-ray-protective clothing is classified by the European production standard EN 61 331-3. To evaluate protective effects of lead-free materials according to this standard, the certifying offices as well as customers solely refer to the lead equivalent (LE). The LE of lead-free protective clothing, however, depends on the tube voltage (energy spectrum). Therefore, stating a single value for x-ray-protective clothing does not reveal the protective efficacy for the complete range of energy as applied in clinical practice. Moreover, the method of narrow beam geometry does not account for information on secondary radiation (scattered and fluorescent radiation) generated within the material. Lead-free materials, however, generate large-scale fluorescent radiation, especially for elements with atomic numbers below 60. As a consequence, full-scale secondary radiation of a given material can only be detected with a broad beam setup. Materials and methods In accordance with IEC 61 331-1, we compared commercially available radiation-protective aprons manufactured with lead-free or partially lead-free materials with aprons manufactured on a lead-oxide basis. In addition to the LE, attenuation ratios and dose-build-up-factors under broad beam-conditions were evaluated. Results In comparison with lead-oxide materials, protection efficacy of lead-free materials is reduced by up to 70 %, particularly for a tube voltage below 80 kV. Lead-composite materials (partially lead-free materials) are less affected. Conclusion Users and patients wearing lead-free x-ray-protective clothing might unknowingly be exposed to a much larger dose than generally assumed. In the future, radiation protection rating should exclusively refer to the "attenuation ratio", which is based on broad beam geometry and characterizes radiation attenuation much more precisely than the lead equivalent.

There is an increasing need for efficient beta detectors to fulfil ICRU recommendations for new quantities especially in the field of medical physics and retrospective dosimetry. The thermoluminescence properties of thin LiF:Mg, Cu, P (GR-200F) tapes produced in 1998 by Sange Company, People's Republic of China, are investigated and compared with those of highly sensitive thin Al2O3:C beta detectors as regards their applicability in the detection of low energy photons and beta particles. The radiation dose response, minimum detectable dose, reproducibility of measurements and effect of residual signal at low dose are assessed for the possible low level beta dosimetry use. The radiation dose response and photon and beta detection efficiencies are tested underpractical laboratory conditions. The effects of indoor fluorescent light and residual signal after the first read-out are investigated with a view to optimising handling conditions such as post-irradiation and pre-heating treatments for routine dosimetry. The photon energy responses of the detectors are investigated using 150 keV filtered x-rays and 60Co gamma-rays.

Neoplastic transformation of human CGL1-hybrid cells was examined after exposure to 29 kV x-rays (mammography x-rays) and conventional 220 kV x-rays. The study was designed to repeat, under well-defined irradiation and culture conditions, an earlier investigation by Frankenberg et al. (Radiat Res, 2002), and to assess the validity of the high RBE values of 29 kV x-rays that had been reported. The experiments with the two types of x-rays were performed simultaneously and shared the same controls. The transformation yields with both radiation qualities were fitted to the linear-quadratic dependence on absorbed dose, and a corresponding analysis was performed for the data earlier obtained by Frankenberg et al. The transformation yields in the present study exceed those in the earlier investigation substantially, and it appears that the difference reflects inadequate feeding conditions of the cell cultures in the early experiments. The standard error bands of the dose response curves are derived and are seen to be considerably more narrow in the present results. The lowest dose of the 29 kV x-rays was 1 Gy in both studies, and at this dose the RBE vs. the conventional x-rays has now been found to be 2 with a 95% confidence interval of 1.4-2.6. The previous result was about 3.2, but the 95% confidence is very broad for these data. The estimated limit at low doses is 3.4 in the present experiments with a confidence interval that extends from less than 2 to large values.

This paper uses the task of microcalcification detection as a benchmark problem to assess the potential for dose reduction in x-ray mammography. We present the results of a newly developed algorithm for detection of microcalcifications as a case study for a typical commercial film-screen system (Kodak Min-R 2000/2190). The first part of the paper deals with the simulation of dose reduction for film-screen mammography based on a physical model of the imaging process. Use of a more sensitive film-screen system is expected to result in additional smoothing of the image. We introduce two different models of that behaviour, called moderate and strong smoothing. We then present an adaptive, model-based microcalcification detection algorithm. Comparing detection results with ground-truth images obtained under the supervision of an expert radiologist allows us to establish the soundness of the detection algorithm. We measure the performance on the dose-reduced images in order to assess the loss of information due to dose reduction. It turns out that the smoothing behaviour has a strong influence on detection rates. For moderate smoothing. a dose reduction by 25% has no serious influence on the detection results. whereas a dose reduction by 50% already entails a marked deterioration of the performance. Strong smoothing generally leads to an unacceptable loss of image quality. The test results emphasize the impact of the more sensitive film-screen system and its characteristics on the problem of assessing the potential for dose reduction in film-screen mammography. The general approach presented in the paper can be adapted to fully digital mammography.

The Commission of the European Communities (CEC) research project "Predictivity and optimisation in medical radiation protection" addressed fundamental operational limitations in existing radiation protection mechanisms. The first part of the project aimed at investigating (1) whether the CEC image quality criteria could be used for optimization of a radiographic process and (2) whether significant differences in image quality based on these criteria could be detected in a controlled project with well known physical and technical parameters. In the present study, chest radiographs on film were produced using healthy volunteers. Four physical/technical parameters were varied in a carefully controlled manner: tube voltage (102 kVp and 141 kVp), nominal speed class (160 and 320), maximum film density (1.3 and 1.8) and method of scatter reduction (grid (R=12) and air gap). The air kerma at the entrance surface was measured for all patients and the risk-related dose H(Golem), based on calculated organ-equivalent dose conversion coefficients and the measured entrance air kerma values, was calculated. Image quality was evaluated by a group of European expert radiologists using a modified version of the CEC quality criteria. For the two density levels, density level 1.8 was significantly better than 1.3 but at the cost of a higher patient radiation exposure. The correlation between the number of fulfilled quality criteria and H(Golem) was generally poor. An air gap technique resulted in lower doses than scatter reduction with a grid but provided comparable image quality. The criteria can be used to highlight optimum radiographic technique in terms of image quality and patient dose, although not unambiguously. A recommendation for good radiographic technique based on a compromise between image quality and risk-related radiation dose to the patient is to use 141 kVp, an air gap, a screen-film system with speed 320 and an optical density of 1.8.

Regulla, D., Panzer, W., Schmid, E., Stephan, G. and Harder, D. Detection of Elevated RBE in Human Lymphocytes Exposed to Secondary Electrons Released from X-Irradiated Metal Surfaces. Radiat. Res. 155, 744-747 (2001). Monolayers of human lymphocytes, attached to a 2-microm Mylar film, were irradiated with 60 kV X rays in the presence and absence of a 150-microm gold film backing the Mylar film. With the gold film present, the absorbed dose imparted to the cells was increased by a factor of 45.4 due to the release of photoelectrons from the gold film. The frequencies of dicentric chromosomes and centric rings as well as of excess acentric fragments were increased in agreement with this dose enhancement, and in addition an RBE of about 1.7 compared to the frequencies observed in the absence of the gold film was found. These radiation effects, which contribute to risk considerations in radiology, are interpreted in terms of the increased dose-mean restricted LET of the photoelectrons backscattered from the metal and slowed down in the Mylar film before they enter the cell layer.

The total measured dose-area product (DAP), fluoroscopic screening time and the number of radiographic exposures were surveyed in a study on micturating cystourethrography (MCU) performed in 1997/1998 in 12 children's clinics in seven European countries. The examination technique and, consequently, total DAP varied widely within and between radiology departments. The evaluation of image quality of original radiographic exposures from the MCUs also showed a wide variation which was not correlated to dose. The quality criteria developed for and used for the MCU in this study proved to be useful for evaluation of spot film images. The wide variations in technique, dose and image quality, even for the relatively homogeneous infant group, indicate the necessity of further optimisation in fluoroscopy.

The aim of the first this work part of the EU-project, Trial I, was to evaluate and possibly improve the CEC image criteria for radiographic chest images. Chest images of healthy volunteers were acquired using different technique factors. The image criteria were used as a tool to discriminate between the different images. The technique factors were chosen so that the image quality would differ slightly. Four different technique parameters, each with two possible settings, used in clinical practice today, were used: tube voltage - 102 and 141 kV; screen/film speed - 160 and 320; maximum optical density in the parenchyma - 1.3 and 1.8; method for scatter reduction - air gap 30/390 and moving grid40/12. The results showed that the image criteria were able to separate between different technique groups. Some conclusions can be drawn from the results Optical density 1.8 was better than 1.3 independent of the other parameters. . Among the six combinations ranked best , four used tube voltage 141 kV and four used air gap technique for scatter reduction. No difference was seen for screen/film speed. No correlation was seen between the ranking of the systems and patient dose. (Less)

The voxel phantom Golem was used for the dosimetric part of the EU research project 'Predictivity and Optimisation in Medical Radiation Protection'. A risk-related dose quantity, H Golems , was evaluated using calculated organ equivalent dose conversion coefficients and entrance air kerma values measured during the clinical examinations. Two types of examinations were considered: chest PA examinations, which were performed in 16 groups involving different speed classes, mean optical densities, tube voltages and methods of scatter reduction; and lumbar spine AP examinations, for which four different combinations of speed class and tube voltage were used. For the chest examinations, the expected effects of different examination techniques are clearly mirrored by the dosimetric results. For the lumbar spine examinations, part of the expected results was concealed by the unwanted influence of the patient diameters on the doses, which could be partially eliminated by adapting the voxel phantom to different sizes.

Physical and radiobiological evidence is summarised conceming significant dosimetric effects in tissue adjacent to a solid gold surface, when this interface zone is irradiated with X rays of qualities common in medical diagnosis. Physical measurements result in a more than 100-fold dose enhancement attributable to photoelectrons and Auger electrons emerging from the gold surface. The enhanced interface doses are shown to correspond with significantly diminished cell growth and cell survival as well as with enhanced oncogenic transformation and chromosome aberrations. Preliminary results of Monte Carlo based track structure calculations at the interface show electron spectra with a noticeable component of low energy electrons, so that LET effects might be expected.

The revised EC patient Directive 97/43/EURATOM introduces a number of new and extremely relevant requirements into the legal framework of radiation protection of persons who undergo medical exposure throughout Europe. Key elements of the most relevant changes involve a more objective assessment of radiological performance. In particular, the establishment of optimisation strategies involving clinical and patient dose audits, as well as quality assurance, will be required. There is no doubt that within this changing framework for radiation protection of the patient, advice and guidance regarding best practice at a European level will play a vital role in the achievement of consistent and harmonised practice. In order to establish a starting point for both the structure and content of advice and guidance on best practice for radiation protection of the patient, the Commission of European Communities has established European Guidelines on Quality Criteria for diagnostic radiographic images for adult and paediatric patients as well as computed tomography. These documents have already been made available throughout Europe in English and translation into a number of European Languages is under way for re-circulation within specific Member States. Whilst this process was continuing a Fourth Framework Research Programme has been under way in the period 1996-2000 to develop and evaluate further the robustness of the Quality Criteria for diagnostic radiographic images for adult patients. An overview is presented of the most relevant findings of the Fourth Framework Research Project with a strong emphasis on operational outcomes relevant to focused multipartner, multinational research programmes of a multidisciplinary nature. Detailed findings of the project will be presented elsewhere in the meeting and through future publications.

The rapid technological development within CT has resulted in a continuing expansion of CT examinations. Due to the high radiation dose often delivered by CT it is important to ensure that the required diagnostic information is achieved with minimum dose to the patient. The European Guidelines on Quality Criteria for CT includes anatomical/diagnostic image quality criteria for six main groups of examinations: cranium, face and neck, spine, chest, abdomen and pelvis, and bones and joints. The clinical use of such criteria has been limited and a pilot multicentre study has therefore been performed with regard to their utility in clinical practice for five types of examinations: (1) face and sinuses, (2) vertebral trauma, (3) HRCT of the lung, (4) liver and spleen, and (5) osseous pelvis. The results show that the diagnostic criteria can be used to optimise CT procedures to achieve doses that are as low as consistent with required diagnostic image quality.

Computed tomography (CT) is firmly established as a major source of population exposure from diagnostie X ray examinations. National surveys have highlighted significant variations in dose between individual scanners and potential scope for improvement in practive. Reference doses are already recognised as a practical way of promoting optimisation of patient protection and accordingly this concept has been claborated for CT by the European Commission in Working Document EUR 16262 (1997 ) on Quality Criteria for CT. Two reference dose quantities have been defined on the basis of measurements of the computed tomography dose index (CTDI ) made with a pencil ionisation chamber in standard head or body CT dosimetry phantoms: weighted CTDI for a single lice and, with due account of the thickness and number of slices in a complete examination, dose-lenght product. Pending trials of the quality criteria, some initial reference doses have been proposed using survey data from the UK for 1989.

Backscatter factors were determined for x-ray beams relevant to diagnostic radiology using Monte Carlo methods. The phantom size considered most suitable for calibration of dosimeters is a cuboid of 30 x 30 cm2 front surface and 15 cm depth. This phantom size also provides a good approximation to adult patients. Three different media were studied: water, PMMA and ICRU tissue; the source geometry was a point source with varying field size and source-to-phantom distance. The variations of the backscatter factor with phantom medium and field geometry were examined. From the obtained data, a set of backscatter factors was selected and proposed for adoption as a standard set for the calibration of dosimeters to be used to measure diagnostic reference doses.

Es wird uber den Fall einer 43 Jahre alten Patientin berichtet, die im Rahmen eines akuten Hinterwandinfarktes zu Hause einen Kreislaufstillstand erlitt. Nach 20minutiger Reanimation durch den Ehemann sowie den in der Nachbarschaft wohnenden Hausarzt stellte der eintreffende Notarzt Kammerflimmern fest. Bei zweiundvierzig Defibrillationen lies sich kein dauerhafter Eigenrhythmus herstellen. Unter mechanischer Reanimation durch einen Anasthesisten wurde die Patientin in unsere Klinik transportiert, wo sie 90 min nach Beginn des Kammerflimmerns eintraf. Unter Fortfuhrung der mechanischen Reanimationsmasnahmen erfolgte uber die Leistengefase die perkutane Implantation einer Herz-Lungen-Maschine (pHLM) durch den vorab uber Funk informierten Kardiologen. Dadurch war es moglich, unter laufender pHLM (4–5 l/min) die Patientin von der Notaufnahme in den Herzkatheter zu transportieren. Es fand sich ein proximaler Verschlus einer dominanten rechten Kranz-arterie. Nach Rekanalisation des Gefases konnte durch Defibrillation ein stabiler Sinusrhythmus hergestellt werden. Nach Einlegen einer intraaortalen Ballonpumpe (IABP) konnte die Pumpleistung der pHLM in 2stundigen Abstanden reduziert werden. Nachdem der Kreislauf der Patientin schrittweise von der pHLM entwohnt wurde, erfolgte nach 10 h die Explantation der pHLM. Eine Augmentation durch die IABP war noch drei weitere Tage notwendig. Nach insgesamt neun Wochen konnte die Patientin ohne neurolo-gische Defizite nach Hause entlassen werden. Durch den Einsatz einer pHLM konnen Patienten, die unter mechanischer Reanimation in eine Klinik eingeliefert werden, initial stabilisiert und so weiteren diagnostischen und therapeutischen Masnahmen zugefuhrt werden. Die Indikation fur den Einsatz einer pHLM im therapierefraktaren Kreislaufstillstand ist durch den Notarzt vor Ort zu stellen, wenn sich aufgrund von Anamnese und klinischem Bild therapeutische Optionen ergeben.

Zusammenfassung Es wird eine Methode beschrieben, nach welcher die spektralen Dosisbeitrage aus der Anzeige eines allgemein gebrauchlichen Filmdosimeters, den optischen Dichten der Filmfelder hinter den einzelnen Filtern, bestimmt werden konnen, wenn dieses mit Rontgenstrahlung im Energiebereich bis 150 keV senkrecht von vorne bestrahlt wurde. Grundlage des Verfahrens ist die genaue Kenntnis der Antwort des Dosimeters auf einen Satz von Kalibrierexpositionen durch Rontgenstrahlung definierter Dosis und spektraler Verteilung und die parametrisierte Darstellung der Optische-Dichte-Kurven (Schwarzungskurven). In einem Optimie-rungsverfahren, basierend auf dem Programmpaket MINUIT, werden die in einer zu analysierenden Dosimeterantwort enthaltenen Beitrage aus diesem Satz von Kalibrierexpositionen bestimmt. Durch Anwendung des Verfahrens auf die Auswertung der Dosimeterantwort von Kalibrierexpositionen wurde in einem ersten Konsistenztest festgestellt, ob diese eindeutig wiedererkannt werden. Im weiteren wurden Filmdosimeter mit bekannten Strahlenqualitaten und Dosen bestrahlt, um die Resultate zu uberprufen.

A 24-year old student died from asphyxiation while filling flasks with liquid nitrogen. The upper and lower extremities and the back were frozen. The face, ears and neck were livid with a horizontal line of demarcation. A few wide ventricular complexes were seen in the initial ECG, followed by asystole. The patient's trachea was intubated, his lungs ventilated with 100% oxygen and CPR initiated. The site of larynx and pharynx were without pathological findings. 250 ml of a crystalloid solution were infused into the external jugular vein. It was not possible to measure the body temperature. Venous blood gas analysis showed a metabolic acidosis and hyperkaliaemia. CPR was terminated after 90 minutes. Own protection is most important for the rescue team if a nitrogen atmosphere is expected.

Photon spectra are reported that result from the scatter of diagnostic X rays at an appropriate water phantom that represents a patient. The tube voltages considered are between 52 kV and 110 kV, the scatter angles range from 10° to 142° to the normal radiation incidence direction. All spectral measurements were performed with a high-purity germanium detector. Spectral photon fluences are computed from the measured pulse height distribution by using an unfolding procedure. The required response functions of the detection system were obtained by using Monte Carlo methods. Reference is made to a catalogue compiling 35 spectra of scattered X rays in diagnostics resulting from a human substitute, together with information on relevant primary field parameters as well as air kerma for the scattered X rays.

Background: Basic life support guidelines of the European Resuscitation Council (ERC) suggest a modified type of recovery position compared to that recommended by the American Heart Association (AHA). However, anecdotal reports and the results of a small study by Fulstow and Smith (Resuscitation 1993; 26: 89–91) gave evidence that the new ERC position may cause an impairment of perfusion of the lower forearm. The aim of our study was to evaluate the effects of different recovery positions on arterial perfusion and venous drainage of the forearm. Methods: We placed 20 young healthy volunteers randomly in either ERC or AHA position for 15 min first, and in the other position thereafter. Before and between volunteers were positioned supine. In a second series 10 volunteers were positioned according to the same protocol in semiprone positions as described by Morrison, Mirakhur and Craig (MMC), and Rautek's position, respectively. Forearm perfusion indices of the dependent arm were continuously assessed by photoplethysmographic pulsatility change, photoplethysmographic volume change, invasive peripheral venous pressure and non-invasive blood pressure amplitude. Subjective discomfort was assessed non-qualitatively. Results: All indices of arterial perfusion demonstrated an impairment of arterial inflow in ERC, MMC and Rautek's position as well as venous congestion in these three positions. On the contrary, AHA position was associated with no significant changes of arterial flow and only moderate, insignificant signs of venous congestion. Conclusion: The results of this study suggest that AHA position causes less circulatory disturbances than the ERC, MMC and Rautek's positions.

PURPOSE Estimation of radiogenic risks for patient and radiologist in chemoembolisation of hepatocellular carcinoma (HCC) and laser angioplasty of the pelvic arteries. METHODS In 5 chemoembolisations of HCC (4 males, one female) and 6 laser angioplasties of the pelvic arteries (5 males, one female) the surface doses received by patient and operator were measured using thermoluminescent dosimeters in standardised positions. The organ doses of the patient were derived by conversion factors employed on the measured surface doses. Effective dose was determined according to the recommendations of ICRP 60. RESULTS The risk of lethal malignant disease and genetic disorder derived from the doses in the patient was found to be of the magnitude of 10(-4)-10(-5). The thresholds for transient erythema of the skin and depression of hematopoiesis can be reached after high expositions. A theoretical maximum of 700 laser angioplasties of the pelvic arteries allowable in one year was calculated based on the dose to the operator's left hand. For chemoembolisation of HCC, the dose to the left eye lens would reach the yearly maximum after approximately 1000 procedures. Remarkable risks for malignant disease of skin and thyroid as well as detectable opacities of the eye lens can occur after frequent interventions for many years. CONCLUSIONS Because of the lower life expectancy the patient's risk for stochastic effect can be seen as minimal. No clinically relevant deterministic effects will occur. In the case of frequent interventions, the dose absorbed by the radiologist is likely to exceed the prescribed dose limit and to cause remarkable risk for stochastic and non-stochastic effects after many years.

A 38-year-old physician presented with a 9-month history of progressive self-administration of oral prednisone < or = 160 mg per day for Addison's disease. Examination demonstrated typical Cushingoid features and bilateral proptosis with elevated intraocular pressure. Computed tomography disclosed increased intraorbital adipose tissue. We hypothesize that the increased intraorbital adipose deposition was due to the differential binding of glucocorticoids to adipose tissue receptors and an enhancement of lipoprotein lipase activity. We conclude that the findings in this case may be related to glucocorticoid-induced changes in the ocular and periorbital structures. Cushing's syndrome should be considered in the differential diagnosis of acquired exophthalmos and elevated intraocular pressure and findings of increased orbital fat on orbital imaging.

Since 2007 interhospital transport of intensive care patients in Lower Saxony appertains to the performance requirements of emergency medical services. Against this background the Working Group for Evaluation of Intensive Care Transport (Arbeitsgemeinschaft Evaluation Intensivverlegung) was established. This group formulated standardized definitions for the requirements of intensive care transport vehicles and a federal statewide monitoring of intensive care transport was implemented to analyze if simultaneously on-call intensive care transport systems (intensive care helicopter and ground based mobile intensive care units) can be deployed need-based and efficiently.A prospective follow-up study and evaluation of intensive care transport in Lower Saxony between April 1(st) 2008 and July 31(st) 2010 was carried out.A total of 6,779 data records were evaluated in this study of which 4,941 (72.9%) missions were located in Lower Saxony, 2,928 (43.2%) missions were carried out by helicopters and 3,851 (56.8%) by ground based mobile intensive care units. The mean duration of a mission was 3 h 59min±2 h 25 min, 4 h 39 min±2 h 23 min by ground based mobile intensive care units and 2 h 21 in±30 min by helicopter units. All systems proved to be feasible for intensive care transport. The degree of urgency was estimated correctly in 94.8% of the evaluated missions and 58.0% of the transfers could not be deployed. In 76.8% patients were transferred to hospitals with a higher level of medical care, 51.7% of patients were transferred for intensive care therapy and 40.4% for an operation/intervention. Of the patients 38.2% required mechanical ventilation and in 48.3% invasive monitoring was carried out.Interhospital transfer of intensive care patients can be carried out need-based with a limited number of intensive care transport vehicles if the missions are deployed effectively by standardized disposition in accordance with performance requirements.

Zusammenfassung Im Rahmen eines EG-Projektes wurde die Patientenexposition bei padiatrischen Rontgenuntersuchungen in 90 Kinderkliniken durch unmittelbare Dosismessung im Nutzstrahlenbundel ermittelt. Als Dosimeter dienten TLD-chips aus CaF 2 , die bei 70 kV zur Messung der Oberflachendosis in µGy kalibriert worden waren und mit der Post versandt wurden. Die Dosen pro Rontgenaufnahme liegen je nach Untersuchung zwischen dem unteren Bereich 26 - 80 µGy fur Thorax ap bei Fruhgeborenen und dem oberen Bereich 597 - 1686 µGy fur Schadel ap/pa im Alter von 10 Monaten. Die (hier durch das 1. und 3. Quartil der bei einer bestimmten Untersuchung erhaltenen Dosiswerte dargestellte) Streubreite kann als Hinweis auf noch bestehende Optimierungsmoglichkeiten gewertet werden.

Zusammenfassung In einem Alderson-Rando-Rumpfphantom wurden bei einer Ganzkorpertomographie (125 kV, 2.2 mm Al + 0.4 mm Cu, 122 Schichten) und bei 60 Co-Ganzkorperbestrahlungen (ap und pa) Gewebedosismessungen mit TLD an 28 Targetpositionen ausgefuhrt. Aus den CT-Daten wurde auserdem ein dreidimensionales Voxel-Phantom konstruiert, das aus 8 verschiedenen Medien bestand und Monte-Carlo-Simulationen der gleichen Ganzkorpertomographie und Ganzkorperbestrahlungen erlaubte. Der resultierende Unterschied zwischen gemessenen und berechneten Gewebedosen an den einzelnen Targetpositionen variierte zwischen - 15 % und + 15 %; sein mittlerer Betrag war stets kleiner als 5 %. Diese Untersuchung erbringt somit eine direkte und detaillierte experimentelle Prufung und Bestatigung von Dosisberechnungen mithilfe dreidimensionaler Voxeiphantome.

The use of CT scans has increased rapidly during the last years in adults and children as well. CT involves larger radiation doses than the more common conventional x – ray imaging procedures. To examine the biological effect in the peripheral blood of the paediatric patients chromosome analysis was carried out in 10 children for whom the medical justifications for CT examinations were accidental injuries and not diseases as investigated in earlier studies. Blood samples were taken before and after CT scans. Chromosome analysis was carried out in lymphocytes by fluorescence plus Giemsa (FPG) staining exclusively in metaphases of the first cell cycle in vitro. The mean blood dose of the 10 children was about 12.9 mGy which was determined by a newly developed dose estimation. Based on more than 20,000 analysed cells it was found that after CT examination the mean frequencies of dicentrics and excess acentric fragments in lymphocytes were significantly increased. By subdividing the children into two age groups, those with an age from 0.4 years to 9 years and from 10 years to 15 years, it became obvious that the observed increase in chromosome aberrations was mainly contributed by the younger age group. In this group the frequency of dicentrics was significantly increased whereas in the older group the observed increase was not significant. Further investigations will be necessary to confirm these results.

Evaluation of the results of routine personnel monitoring and extra routine field measurements revealed that occupational whole-body doses, as determined by means of the routine personnel dosemeter, are normally very low, while partial body doses, especially doses to the hands and fingers may reach dose limits. This indicates the need for suitable monitoring of partial body doses

To determine whether computed tomography (CT) could enhance the chromosome aberration yields in paediatric patients.Blood samples were taken before and after CT scans from 10 children for whom the medical justifications for CT examinations were accidental injuries and not diseases as investigated in earlier studies. Chromosome analysis was carried out in lymphocytes by fluorescence plus Giemsa (FPG) staining exclusively in metaphases of the first cell cycle in vitro.The mean blood dose of the 10 children was about 12.9 mGy which was determined by a newly developed dose estimation. Based on more than 20,000 analyzed cells it was found that after CT examination the frequencies of dicentrics (dic) and excess acentric fragments (ace) in lymphocytes were significantly increased. By subdividing the children into two age groups, those with an age from 0.4 years to 9 years and from 10 - 15 years, it became obvious that the observed increase in chromosome aberrations was mainly contributed by the younger age group. In this group the frequency of dicentrics was significantly increased whereas in the older group the observed increase was not significant.Our results demonstrate that CT examinations enhance the dicentrics yields in peripheral lymphocytes of children aged up to 15 years. Since in particular significantly increased dicentric yields could be observed in children with an age from 0.4 - 9 years, it can be assumed that children younger than 10 years may be more radiation sensitive than older subjects.

A non-standard scanning device with dose-reduction potential was proposed at the SPIE Medical Imaging conference 2006. The new device obtains the Radon data after the X-ray beam is collimated through a special mask. This mask is combined with a new geometry that permits an efficient data collection, thus the device has the potential of reducing the dose by a factor of two. In this work, we report a prototype of the new device and experimental data acquisition using only the mask of the new scanning geometry. In order to obtain the optimal parameters for the scanning device, several factors have been considered, including detector elements and shielding shape, fan beam angle, speed of the source rotation and materials employed. The calibration of the detector elements needs especial attention, due to the dependence of the detector response on the energy of the X-rays. A simplfied version of the device was designed and mounted. Phantom data were acquired using this prototype and were used to test the performance of the new design. The results obtained are highly promising, even though the prototype developed does not make use yet of all the potential features proposed in the theory.

Out-of-hospital airway management confronts emergency medical teams with complex challenges. To date no specific data are available on the qualifications of emergency physicians (EPs) and the quality of emergency equipment in northern Germany.This study surveyed individual EPs at regional emergency dispatch centres about their personal knowledge and skills, and the procedures and equipment used in out-of-hospital airway management.A total of 606 EPs from 59 of the 66 (89.4%) regional emergency dispatch centres surveyed responded and 56.1% of the EPs questioned were anesthesiologists. The other EPs were qualified in either internal medicine (22.6%), surgery (12.4%), general medicine (5.6%) or other specialties (3.3%). All (100%) of the EPs trained in anesthesia and 35.2% of the other EPs reported that they had performed more than 100 in-hospital endotracheal intubations (ETI). 93% of all EPs rated out-of-hospital ETI as more difficult than in-hospital ETI. A total of 33.0% of anesthesia-trained EPs and 6.1% of the other EPs used muscle relaxants for ETI in more than 20% of the cases. Of the anesthesia-trained EPs 38.1% used expiratory CO(2) monitoring to verify tube placement compared to 12.1% of the other EPs. A total of 97.8% of anesthesia-trained EPs reported having used an extra-glottic airway device more than 20 times compared to 11.1% of the other EPs. For the emergency equipment 44.4% included an extraglottic airway device, 57.8% a cricothyrotomy set and 27.1% CO(2) monitoring options.Neither the emergency equipment nor the physicians' knowledge and skills were sufficient to meet the special demands of out-of-hospital airway management, particularly among non-anesthesiologists.

Experiments were designed and performed in order to investigate whether or not the different cellular energy deposition patterns of photon radiation with different energies (29 kV, 220 kV X rays; Co-60, Cs-137-gamma-rays) and alpha-radiation from an Am-241 source differ in DNA damage induction capacity in human cells. For this purpose, the alkaline comet assay (single cell gel electrophoresis) was applied to measure the amount of DNA damage in relation to the dose received. The comet assay data for the parameters '% DNA in the tail' and 'tail moment' for human peripheral lymphocytes did not indicate any difference in the initial radiation damage produced by 29 kV X rays relative to the reference radiations, 220 kV X rays and the gamma rays, whether for the total mean dose range of 0-3 Gy nor in the low-dose range. In contrast, when the 'tail length' data were analysed saturation of the fitted dose response curve appeared for X rays at about 1.5 Gy but was not apparent for gamma rays up to 3 Gy. Preliminary data for alpha exposures of HSC45-M2 cells showed a significant increase in DNA damage only at high doses (2 Gy Am-241), but the damage at 2 Gy exceeded the damage induced at 2 Gy by Cs-137-gamma-rays by a factor of 2.5. In contrast, other experiments involving different cell systems and DNA damage indicators such as chromosomal aberrations have detected a significant increase in DNA damage at much lower doses, that is at 0.02 Gy for Am-241 and depicte a higher biological effectiveness. These results indicate that differences in biological effects arise through downstream processing of complex DNA damage.

For 8 voxel models of a compressed breast (4-7 cm thickness and two orientations for each thickness) and 14 radiation qualities commonly used in mammography (HVL 0.28-0.50 mm AI), tissue dose conversion coefficients were calculated for a focus-to-film distance of 60 cm using Monte Carlo methods. The voxel models were segmented from a high-resolution (slice thickness of 1 mm) computed tomography data set of an ablated breast specimen fixated while being compressed. The contents of glandular tissues amounted to 2.6%, and were asymmetrically distributed with regard to the midplane of the model. The calculated tissue dose conversion coefficients were compared with the recent literature values. These earlier tissue dose conversion coefficients were also calculated using Monte Carlo methods and breast models of various thickness, but these consist of homogeneous mixtures of glandular and adipose tissues embedded in 5 mm pure adipose tissue both at the entrance and exit sides. The results show that the new glandular tissue dose conversion coefficients agree well with the literature values for those cases where the glandular tissue is predominantly concentrated in the upper part of the model. In the opposite case, they were lower by up to 40%. These findings reveal a basic problem in patient dosimetry for mammography: glandular dose is not only governed by the average breast composition, which could be derived from the breast thickness, but also by the local distribution of glandular tissue within the breast, which is not known.

Though mammography is one of the most sensitive methods to detect breast cancer, the benefit of the mammography screening programmes is still not clearly proven. One of the reasons is the radiation dose delivered by the examinations. Simulations of the radiation transport based on realistic breast phantoms are a useful tool to estimate the dose for the risk relevant parenchymal tissue. Specimens of real breasts have been fixated using a specially designed process while being compressed as in mammography. They have been scanned using the high-resolution mode of a CT. A segmentation has been carried out by assigning the voxels to different tissues. The resulting voxel phantom allows the assessment of tissue doses by Monte-Carlo calculations and can be used to simulate the diagnostic outcome of different imaging procedures. Three different tissues were separated: skin, adipose and 'breast tissue'. This allows reasonable calculations of the average glandular doses in mammography.

The European Commission (EC) quality criteria for screen-film mammography are used as a tool to assess image quality. A new set of criteria was developed and initially tested in a previous study. In the present study, these criteria are further evaluated using screen-film mammograms that have been digitised, manipulated to simulate different image quality levels and reprinted on film. Expert radiologists have evaluated these manipulated images using both the original (EC) and the new criteria. A comparison of three different simulated dose levels reveals that the new criteria yield a larger separation of image criteria scores than the old ones. These results indicate that the new set of image quality criteria has a higher discriminative power than the old set and thus seems to be more suitable for evaluation of image quality in mammography.

Experiments using the alkaline comet assay, which measures all single-strand breaks regardless of their origin, were performed to evaluate the biological effectiveness of photons with different energies in causing these breaks. The aim was to measure human lymphocytes directly for DNA damage and subsequent repair kinetics induced by mammography 29 kV X rays relative to 220 kV X rays, 137Cs gamma rays and 60Co gamma rays. The level of DNA damage, predominantly due to single-strand breaks, was computed as the Olive tail moment or percentage DNA in the tail for different air kerma doses (0.5, 0.75, 1, 1.5, 2 and 3 Gy). Fifty cells were analyzed per slide with a semiautomatic imaging system. Data from five independent experiments were transformed to natural logarithms and fitted using a multiple linear regression analysis. Irradiations with the different photon energies were performed simultaneously for each experiment to minimize interexperimental variation. Blood from only one male and one female was used. The interexperimental variation and the influence of donor gender were negligible. In addition, repair kinetics and residual DNA damage after exposure to a dose of 3 Gy were evaluated in three independent experiments for different repair times (10, 20, 30 and 60 min). Data for the fraction of remaining damage were fitted to the simple function F(d) = A/(t + A), where F(d) is the fraction of remaining damage, t is the time allowed for repair, and A (the only fit parameter) is the repair half-time. It was found that the comet assay data did not indicate any difference in the initial radiation damage produced by 29 kV X rays relative to the reference radiation types, 220 kV X rays and the gamma rays of 137Cs and 60Co, either for the total dose range or in the low-dose range. These results are, with some restrictions, consistent with physical examinations and predictions concerning, for example, the assessment of the possible difference in effectiveness in causing strand breaks between mammography X rays and conventional (150-250 kV) X rays, indicating that differences in biological effects must arise through downstream processing of the damage.

Currently, lead-free x-ray-protective clothing is classified by the European production standard EN 61 331-3. To evaluate protective effects of lead-free materials according to this standard, the certifying offices as well as customers solely refer to the lead equivalent (LE). The LE of lead-free protective clothing, however, depends on the tube voltage (energy spectrum). Therefore, stating a single value for x-ray-protective clothing does not reveal the protective efficacy for the complete range of energy as applied in clinical practice. Moreover, the method of narrow beam geometry does not account for information on secondary radiation (scattered and fluorescent radiation) generated within the material. Lead-free materials, however, generate large-scale fluorescent radiation, especially for elements with atomic numbers below 60. As a consequence, full-scale secondary radiation of a given material can only be detected with a broad beam setup.In accordance with IEC 61 331-1, we compared commercially available radiation-protective aprons manufactured with lead-free or partially lead-free materials with aprons manufactured on a lead-oxide basis. In addition to the LE, attenuation ratios and dose-build-up-factors under broad beam-conditions were evaluated.In comparison with lead-oxide materials, protection efficacy of lead-free materials is reduced by up to 70 %, particularly for a tube voltage below 80 kV. Lead-composite materials (partially lead-free materials) are less affected.Users and patients wearing lead-free x-ray-protective clothing might unknowingly be exposed to a much larger dose than generally assumed. In the future, radiation protection rating should exclusively refer to the "attenuation ratio", which is based on broad beam geometry and characterizes radiation attenuation much more precisely than the lead equivalent.

The "European Guidelines on Quality Criteria for Diagnostic Radiographic Images" do not address the choice of the film characteristic (HD) curve, which is an important parameter for the description of a radiographic screen-film system. The image contrast of clinical lumbar spine and chest radiographs was altered by digital image processing techniques, simulating images with different HD curves, both steeper and flatter than the original. The manipulated images were printed on film for evaluation. Seven experienced radiologists evaluated the clinical image quality by analysing the fulfilment of the European Image Criteria (ICS) and by visual grading analysis (VGA) of in total 224 lumbar spine and 360 chest images. A parallel study of the effect of the HD curve has also been made using a theoretical model. The contrast (DeltaOD) of relevant anatomical details was calculated, using a Monte Carlo simulation-model of the complete imaging system including a 3D voxel phantom of a patient. Correlations between the calculated contrast and the radiologists' assessment by VGA were sought. The results of the radiologists' assessment show that the quality in selected regions of lumbar spine and chest images can be significantly improved by the use of films with a steeper HD curve compared with the standard latitude film. Significant (p0.05) correlations were found between the VGA results and the calculations of the contrast of transverse processes and trabecular details in the lumbar spine vertebrae, and with the contrast of blood vessels in the retrocardiac area of the chest.

Die Sicherung freier Atemwege kann vielfaltige Gefahren vom Patienten abwenden, beinhaltet aber auch eigene Risiken. Gerade bei erkennbar schwierigen Verhaltnissen oder unter ungunstigen Umstanden gilt es daher, das Risiko fur den Patienten durch Verbesserung der Bedingungen und gute Uber-wachung zu minimieren. Dazu gehoren sowohl die genaue Beobachtung des Patienten („klinischer Eindruck“) als auch der Einsatz von Monitoren. Auch wenn der klinische Eindruck oft das erste wichtige Alarmsignal darstellt, kann er den Beobachter in trugerischer Sicherheit wiegen, wenn der Patient eigentlich noch gar nicht so schlecht aussieht, der Monitor aber schon deutlich pathologische Werte anzeigt. Dies gilt vor allem dann, wenn scheinbar keine Alternative zum geplanten Vorgehen zur Verfugung steht: weil nicht sein kann, was nicht sein darf. Besondere Bedeutung erlangt in diesem Zusammenhang die allgemeine Weisheit, dass in Zweifelsfallen der Blick eines bis dahin Unbeteiligten schnell Klarheit schaffen kann. Deshalb gilt: Wenn moglich, fruhzeitig Hilfe holen!