Predictive preoperative clinical score for patients with liver-only oligometastatic colorectal cancer.

BACKGROUND: Resection of liver metastases from colorectal cancer (CRC) in the oligometastatic stage improves survival and is a potentially curative treatment. Thus, predictive scores that reliably identify those patients who especially benefit from surgery are essential. PATIENTS AND METHODS: In this multicenter analysis, 512 patients had undergone surgery for liver metastases from CRC. We investigated distinct cancer-specific risk factors that are routinely available in clinical practice and developed a predictive preoperative score using a training cohort (TC), which was thereafter tested in a validation cohort (VC). RESULTS: Inflammatory response to the tumor, a right-sided primary tumor, multiple liver metastases, and node-positive primary tumor were significant adverse variables for overall survival (OS). Patients were stratified in five groups according to the cumulative score given by the presence of these risk factors. Median OS for patients without risk factors was 133.8 months [95% confidence interval (CI) 81.2-not reached (nr)] in the TC and was not reached in the VC. OS decreased significantly for each subsequent group with increasing number of risk factors. Median OS was significantly shorter (P < 0.0001) for patients presenting all four risk factors: 14.3 months (95% CI 10.5 months-nr) in the TC and 16.6 months (95% CI 14.6 months-nr) in the VC. CONCLUSIONS: Including easily obtainable variables, this preoperative score identifies oligometastatic CRC patients with prolonged survival rates that may be cured, and harbors potential to be implemented in daily clinical practice.

Novel spectrometers for environmental dose rate monitoring.

A new generation of dosemeters, based on the scintillators LaBr3, CeBr3 and SrI2, read out with conventional photomultipliers, to be used in the field of environmental gamma-radiation monitoring, was investigated. The main features of these new instruments and especially their outdoor performance, studied by long-term investigations under real weather conditions, are presented. The systems were tested at the reference sites for environmental radiation of the Physikalisch-Technische Bundesanstalt. The measurements are compared with that of well characterized classical dose rate reference instruments to demonstrate the suitability of new spectrometers for environmental dose rate monitoring even in adverse weather conditions. Their potential to replace the (mainly Geiger Müller based) dose rate meters operated in about 5000 European early waning network stations as well as in environmental radiation monitoring in general is shown.

INFLUENCE OF RADON PROGENY ON DOSE RATE MEASUREMENTS STUDIED AT PTB'S RADON REFERENCE CHAMBER.

The responses of electronic dose rate meters were investigated in a large volume radon chamber at PTB in a wide range of radon activity concentrations. The measurements were conducted under controlled laboratory conditions and measured dose rate data are compared with Monte-Carlo simulations. Consequences concerning environmental monitoring are described. A further result is that the direct measurement of the dose rates produced by radon progeny in air is hardly possible in radon atmospheres with high activity concentrations, because the major contribution of measured dose rates is produced by radon progeny on the housing of the dose rate instruments. The latter effect largely depends on the ability of surfaces to absorb radon progeny. The Monte-Carlo simulations revealed quantitative results on the height of the single contributions to the total dose rate measured in the radon chamber. When environmental dose rate measurements are performed, the plate-out on detectors can be neglected.

EURADOS strategic research agenda: vision for dosimetry of ionising radiation.

Since autumn 2012, the European Radiation Dosimetry Group (EURADOS) has been developing its Strategic Research Agenda (SRA), which is intended to contribute to the identification of future research needs in radiation dosimetry in Europe. The present article summarises-based on input from EURADOS Working Groups (WGs) and Voting Members-five visions in dosimetry and defines key issues in dosimetry research that are considered important for the next decades. The five visions include scientific developments required towards (a) updated fundamental dose concepts and quantities, (b) improved radiation risk estimates deduced from epidemiological cohorts, (c) efficient dose assessment for radiological emergencies, (d) integrated personalised dosimetry in medical applications and (e) improved radiation protection of workers and the public. The SRA of EURADOS will be used as a guideline for future activities of the EURADOS WGs. A detailed version of the SRA can be downloaded as a EURADOS report from the EURADOS website (www.eurados.org).

EURADOS intercomparisons and the harmonisation of environmental radiation monitoring.

After the Chernobyl nuclear power plant accident in 1986, all Member States of the European Union have installed area dose rate monitoring networks so that radiological incidents can be detected quickly. However, the different technical approaches and procedures led to inconsistencies in the area dose rate data. In the last 15 years, the working group 'Environmental Radiation Monitoring' of the European Radiation Dosimetry Group (EURADOS) has performed six pan-European intercomparison exercises for detector systems operated in national dosimetric early warning networks. These intercomparisons aimed at the harmonisation of area dose rate measurements of radiation monitoring stations in Europe. The intercomparisons revealed differences in technical properties of the dose rate monitoring systems as well as in the calibration and measuring methods that led to deviations of measured dose rate values by a factor of 5 or more under the same measuring conditions. As a result of the intercomparisons, the accuracy of dose rate measurements could be improved considerably. Further progress in metrologically correct measurements of area dose rates in the natural environment and necessary steps towards a metrologically sound pan-European system for environmental radiation monitoring will be discussed.

PTB intercomparisons of passive H*(10) area dosemeters for environmental monitoring.

For measuring the quantity ambient dose equivalent, H*(10), various passive photon and neutron dosemeters have been newly developed and are used in particular for the monitoring of nuclear facilities in the radiation field of the natural ambient radiation. Since 2005, the Physikalisch-Technische Bundesanstalt (PTB) has been performing intercomparisons to study fundamental properties and the long-term behaviour of area dosemeters under real environmental conditions, i.e. the accuracy of photon and neutron measurements performed in the complex natural radiation field. Measuring bodies from four European countries were the participants, including Germany. The goal was, on the one hand, quality assurance for existing passive dosemeters and measurement procedures and, on the other hand, the experimental investigation of whether the requirements of the appropriate standards and guidelines are met in practical use.

A consecutive and prospective stroke database covers the state of Baden-Wuerttemberg with 10.8 million inhabitants in Germany.

BACKGROUND: In 1998 Baden-Wuerttemberg (BW), a federal state in southwest Germany with 10.8 million inhabitants, implemented a structured medical concept for the treatment of acute stroke. METHODS: Since 2004 participation in the BW stroke database is mandatory for all hospitals in BW involved in acute stroke care. The stroke database includes all inpatients ≥18 years of age who have suffered an ischemic or hemorrhagic stroke within 7 days before hospitalization. This article presents methodological aspects and first results of the BW stroke database in the time period from 2007 to 2011. RESULTS: Annual inclusion numbers increased continuously (29,422 vs. 35,724, p < 0.001). Median age of stroke onset was stable over time. The proportion of stroke patients ≥80 years increased from 36.9 to 38.8% (p < 0.001). Rates of patients treated in neurology departments rose from 50.7 to 60.9% (p < 0.001) and numbers of patients treated in stroke units rose from 59.1 to 68.4% (p < 0.001). Admission via emergency medical systems increased from 42.8 to 49.7% (p < 0.001) and arrival within 3 h increased from 29.8 to 34.4% (p < 0.001). CONCLUSION: We present results from a large, prospective and consecutive stroke patient database. This first analysis demonstrates a continuous increase of absolute and relative numbers of stroke patients who arrive within 3 h after onset, are hospitalized in neurology departments and treated in stroke units, and are aged ≥80 years.

[Elzach concept and intervention catalogue of nursing therapy in postacute neurological rehabilitation within the German DRG System]. / Elzacher Konzept und Leistungskatalog der therapeutischen Pflege in der neurologischen Frührehabilitation (Phase B).

The German DRG system defines specialized treatments through a set of minimal requirements, the documentation of which and its assessment by external specialists of the medical service of the statutory health insurance causing frictions between rehabilitation hospitals and the medical service. It is especially problematic to make a clear distinction between nursing care and treatment. To reduce frictions and interface problems, a catalogue of acts of therapy performed by nurses was agreed for neurological early rehabilitation in Baden-Württemberg. This Elzach concept and catalogue describe therapeutic nursing in neurological rehabilitation and increase transparency and accountability both for providers and cost carriers.

Monte Carlo simulations of the photon calibration fields at the underground laboratory of PTB.

A unique photon calibration facility operated by Physikalisch-Technische Bundesanstalt (PTB) provides photon fields with area dose rates in the order of the natural environmental radiation and even below. This facility is located in an underground laboratory in the Asse salt mine at a depth of 490 m below ground, where the ambient dose equivalent rate is only 2 nSv h(-1). Radioactive sources of the nuclides (241)Am, (57)Co, (137)Cs, (60)Co and (226)Ra are used to generate photon fields with different characteristics. In the past, the basic properties of the photon field, especially the area dose rate at the reference point and the mean energy of the photon spectra, were calculated by using analytic methods. However, information about scattered photons is only accessible through an investigation of spectra by performing Monte Carlos simulations. Therefore, the photon spectra at the reference point of the calibration facility were calculated using the Monte Carlo transport code MCNP. The results obtained by using this method are of relevance for the traceability of the reference dose rate values to PTB's primary standards, as well as for the determination of the mean photon energy of the spectra. The latter was calculated with respect to the different quantities 'photon fluence', 'air kerma' and 'ambient dose equivalent'. The origin of the scattered component in the photon spectrum is investigated in detail by studying the photon field produced by the quasi-monoenergetic gamma emitter (137)Cs (E(γ) = 662 keV) under various geometrical conditions. Implications of the Monte Carlo simulations on the traceability of the dose rate reference values as well as on the assessment of uncertainties will be described.

Environmental gamma dosimetry with OSL of alpha-Al(2)O(3):C for in situ sediment measurements.

The physical properties of alpha-Al(2)O(3):C are very similar to that of quartz, which make it an attractive dosimetric material for geological and archaeological dating applications. Storage experiments in an ultra-low-radiation underground environment (UDO at PTB) and gamma-ray spectrometry show that the optically stimulated luminescence (OSL) signal of this material does neither suffer from a significant inherent background caused by traces of radionuclides (<6 microGy a(-1)) nor from fading. After having performed a simple calibration procedure, gamma dosimetry based on alpha-Al(2)O(3):C detectors, which were exposed in a brick block and a lead castle for different periods of time, provided concordant results with dose values derived from independent gamma-ray spectrometric measurements using high-purity germanium and NaI:Tl detectors. These investigations indirectly confirm both the absence of a significant inherent background and fading of the detector material. Small doses of a few micro gray accumulated in short exposure times to environmental radiation can be accurately measured, even when doses (i.e. transport dose) much larger than the actual environmental dose have to be subtracted. It is shown that the OSL signal caused by small transport doses can be easily and reproducibly reset even under difficult field conditions by illuminating the dosemeters with the blue light from Luxeon LEDs. Summarised, alpha-Al(2)O(3):C appears to be the material of choice for dosimetric dating applications of quartz or related materials, when analysed by using OSL.

Traceability of the PTB low-dose rate photon calibration facility.

PTB operates an Underground laboratory for DOsimetry and spectrometry (UDO) in the Asse salt mine at a depth of 490 m below the ground. The ambient dose equivalent rate at UDO is only 2 nSv h(-1). Therefore, UDO is well suited for dosimetry at low dose rates as well as for other low-level measurements. UDO provides the only photon calibration facility worldwide for calibrations at low dose rates (comparable to those in the natural environment and even below), which are traceable to primary standards. Photon fields are generated by using radioactive sources of the following nuclides: (241)Am, (57)Co, (137)Cs, (60)Co and (226)Ra. The dose rates and mean photon energy values at the reference point of this calibration facility were calculated analytically after performing calibration measurements using a secondary standard. This procedure ensures for the traceability of the reference dose rate values to PTB's primary standards. The mean photon energy of each spectrum was calculated with respect to the different quantities air kerma and ambient dose equivalent, respectively. The assessment of the uncertainties of the basic properties of the photon calibration fields will be described.

EURADOS intercomparison 2006 to harmonise European early warning dosimetry systems.

In 2006, the European Radiation Dosimetry (EURADOS) Working Group on Environmental Radiation Monitoring (WG3) organised a third European intercomparison of dosimetry systems operated in national early warning networks. Similar to the intercomparisons in 1999 and 2002, the main aim of this exercise was to support the process of harmonisation of area monitoring in Europe by providing the network operators with basic information on the calibration and performance of their dosimetry systems. In order to characterise these systems, their following basic parameters were investigated: the response to terrestrial and cosmic radiation, the detectors' inherent background, the response at low dose rates, the energy dependence of the response as well as the sensitivity of the detector systems to small changes of the dose rate in a natural environmental radiation field. In the 2006 EURADOS intercomparison, scientists from seven countries participated to study the characteristics of 11 detector systems. All results are presented in terms of the operational quantity ambient dose equivalent, H*(10). The advent of this quantity has caused the development of new detector systems for area monitoring. Some of these new systems participated in a EURADOS intercomparison for the first time. The results are consistently presented together with uncertainties so that statistical effects can be distinguished from real detector features, which improves the interpretation of the results. By using the results of this intercomparison, some detectors were re-calibrated. The achievable improvements concerning harmonisation in dose-rate measurements in the natural environment are discussed.

Improvements of a low-level gamma-ray spectrometry system at the underground laboratory "UDO".

The Physikalisch-Technische Bundesanstalt (PTB) operates various low-background gamma-ray spectrometry systems at the underground laboratory for dosimetry and spectrometry "UDO" in the Asse salt mine. Experiences gained with these detector systems within 10 years of operation have led to technical changes and improvements of the most sensitive detector system at UDO. Key aspects are the precautions to suppress radon (and its progenies) and the performance of the detector system after exchanging the end cap. In addition, a brief summary of recent applications of this gamma-ray detector system will be presented.

A new low-level gamma-ray spectrometry system for environmental radioactivity at the underground laboratory Felsenkeller.

A low-level gamma-ray spectrometry system, based on an HPGe-detector with 92% relative efficiency recently installed in the underground laboratory Felsenkeller at 110 m water equivalent (w.e.) depth, is described. The integral background count rate normalised to the Ge-crystal mass in the energy range from 40 keV until 2.7 MeV of 0.034 s(-1)kg(-1) has been achieved by careful material selection of the detector construction material, a graded shielding construction and effective radon suppression. The detector is highly suitable for the effective surveillance of water for human consumption with decision thresholds for (226)Ra and (228)Ra in the order of some mBq L(-1).

The second EURADOS intercomparison of national network systems used to provide early warning of a nuclear accident.

In 1999 and 2002, the EURADOS Working Group on Environmental Monitoring organised two European intercomparison exercises of national network systems used to provide early warning in case of a nuclear accident. In total, 12 European countries, represented by more than 40 scientists, participated in these two intercomparisons with more than 35 different dose rate detectors. In addition, an in situ gamma spectrometry intercomparison was performed by a group of European scientists during the 2002 exercise. Results of these spectrometry measurements will be reported elsewhere. This report summarises the results of the second intercomparison, performed in 2002, at the environmental dosimetry facilities of the Physikalisch-Technische Bundesanstalt (PTB) in Germany. The unique combination of the ultra-low background Underground Laboratory (UDO) and two free-field sites (a floating platform on a lake showing an almost pure cosmic radiation field and a free-field gamma ray irradiation facility) provide the particular opportunity to precisely quantify the inherent background of the detectors and to calibrate them almost free of any background and traceable to PTB's primary standards. In addition, the intercomparison comprised investigations on the energy and dose rate dependence of the detectors' response to gamma radiation as well as on the response to cosmic radiation. Finally, the sensitivity of the detector systems to small dose rate variations, similar to that caused by a passing overhead radioactive plume, was studied under realistic free-field conditions. Following the Council Directive 96/29/EURATOM, the participants of the 2002 intercomparison were asked to report their results in terms of the operational quantity ambient dose equivalent, H(*)(10). Although the verification of the individual calibrations showed smaller discrepancies than those in the 1999 intercomparison, in a few cases, these discrepancies would be still unacceptably high in the case of a real emergency situation as demonstrated by the plume results. This shows the clear need for further efforts towards a European harmonisation in environmental dosimetry. For this purpose, a further intercomparison shall be held at the PTB in 2006, especially with the participation of new members of the European Union.

Underground measurements of radioactivity.

The exceptional sensitivity of gamma-ray spectrometry in underground laboratories has increasing application because of the important science and technology that it allows to be studied. Early work focused on rare fundamental phenomena, e.g. double beta decay, but a growing number of underground measurements is being performed in fields such as environmental monitoring, surveillance of nuclear activities, benchmarking of other physical techniques and materials selection for equipment which require materials with extremely low levels of radioactivity. This report describes the state of the art in underground gamma-ray spectrometry. Backgrounds of HPGe-detectors at various underground laboratories are presented and compared. Improved techniques and detectors are described and needs of deep underground facilities for higher sensitivity measurements are discussed.

Measurements of 60Co in spoons activated by neutrons during the JCO criticality accident at Tokai-mura in 1999.

Neutron activated items from the vicinity of the place where the JCO criticality accident occurred have been used to determine the fluence of neutrons around the facility and in nearby residential areas. By using underground laboratories for measuring the activation products, it is possible to extend the study to also cover radionuclides with very low activities from long-lived radionuclides. The present study describes gamma-ray spectrometry measurements undertaken in a range of underground laboratories for the purpose of measuring (60)Co more than 2 years after the criticality event. The measurements show that neutron fluence determined from (60)Co activity is in agreement with previous measurements using the short-lived radionuclides (51)Cr and (59)Fe. Limits on contamination of the samples with (60)Co are evaluated and shown to not greatly affect the utility of neutron fluence determinations using (60)Co activation.

Lessons learnt from an international intercomparison of national network systems used to provide early warning of a nuclear accident.

As part of the European Research Council's Fourth Framework Programme, the EURADOS Action Group on Monitoring of External Exposures held an intercomparison of national network systems. This took place during May/June 1999 at the Risø Natural Enviromental Radiation Measurement Station in Denmark and at the Underground Laboratory for Dosimetry and Spectrometry (UDO) of the Physikalisch-Technische Bundesanstalt (PTB) in Germany. The network systems are used continuously to monitor radiation levels throughout a country in order to give early warning of nuclear accidents having transboundary implications. The radiation levels measured are used to estimate the radiation risks to people arising from the accident. Seven European countries participated in the intercomparison with detector systems used in their national network systems as well as with detectors being developed for future use. Since different radiation quantities were measured by the systems (namely exposure, air kerma and ambient dose equivalent), the initial analysis of the intercomparison results was made in terms of the quantity air kerma rate. This report completes the analysis of the results and these are given in terms of air kerma rate in order to be consistent with the preliminary report. In addition, in some cases the results are also given in terms of the quantity measured by each national network system. The experience gained from this intercomparison is used to help organise a follow-up intercomparison to be held at the PTB Braunschweig in September 2002 and in which a further seven or eight countries from Europe will participate.

Experience in long-term neutron dose equivalent measurements using etched track detectors with (n,alpha) converters in moderators.

Etched track Makrofol detectors combined with Kodak BN-1 boron (n,alpha) converters were used inside a 30 cm diameter polyethylene (PE) sphere for the measurement of the neutron ambient dose equivalent. We found unexpectedly high values for the neutron dose equivalent of about 250 microSv instead of 25 microSv for 3 months' exposure in the natural environment. Results from such detectors etched in the authors' labortories revealed that the tracks could only be induced by spontaneous particle emission from the converter. This was confirmed by track diameter analysis and additional special etching of deeper detector layers. Eight surface barrier detectors were used simultaneosly for several days to measure the alpha spectra of the converters. The overall count rate in the energy range 2.5-7.5 MeV was 10 alpha particles d(-1) x cm(-2) for most of the converters and about 10 times less than this for some of them. To identify the nuclides responsible for alpha emission within the converters, gamma spectra of converters were measured for 8 days using a highly sensitive low-background gamma spectrometry system The spectra clearly indicated a small contamination (10 +/- 3 mBq) of the converter foils with 225Ra (T(1/2) = 5.7 y) typically originating from 232Th.