THE GERMAN DOSE RATE MONITORING NETWORK AND IMPLEMENTED DATA HARMONIZATION TECHNIQUES.

Environmental radiation monitoring networks have been established in Europe and world-wide for the purpose of protecting population and environment against ionizing radiation. Some of these networks had been established during the cold war period and were improved after the Chernobyl accident in 1986. Today, the German Federal Office for Radiation Protection (BfS) operates an early warning network with roughly 1800 ambient dose equivalent rate (ADER) stations equally distributed over the German territory. The hardware and software of all network components are developed in-house allowing the continuous optimization of all relevant components. A probe characterization and quality assurance and control program are in place. Operational and technical aspects of the network and data harmonization techniques are described. The latter allows for calculating of the terrestrial and net ADER combined with uncertainties mainly from site specific effects. Harmonized data are finally used as input to the German emergency management system and the European radiological data exchange platform.

Estimating the terrestrial gamma dose rate by decomposition of the ambient dose equivalent rate.

An extensive network of dose rate monitoring stations continuously measures ambient dose rate across Europe, as part of the EURDEP system. Its purpose is early warning in radiological emergencies and documenting its temporal and spatial evolution. In normal conditions, when there is no contribution to the dose rate signal coming from fresh anthropogenic contamination, the data represent the radiation "background", i.e. the combined natural radiation and existing anthropogenic contamination (by global and Chernobyl fallout). These data are being stored, but have so far not been evaluated in depth, or used for any purpose. In the framework of the EU project 'European Atlas of Natural Radiation' the idea has emerged to exploit these data for generating a map of natural terrestrial gamma radiation. This component contributes to the total radiation exposure and knowing its geographical distribution can help establishing local 'radiation budgets'. A further use could be found in terrestrial dose rate as a proxy of the geogenic radon potential, as both quantities are related by partly the same source, namely uranium content of the ground. In this paper, we describe in detail the composition of the ambient dose equivalent rate as measured by the EURDEP monitors with respect to its physical nature and to its sources in the environment. We propose and compare methods to recover the terrestrial component from the gross signal. This requires detailed knowledge of detector response. We consider the probes used in the Austrian, Belgian and German dose rate networks, which are the respective national networks supplying data to EURDEP. It will be shown that although considerable progress has been made in understanding the dose rate signals, there is still space for improvement in terms of modelling and model parameters. An indispensable condition for success of the endeavour to establish a Europe-wide map of terrestrial dose rate background is progress in harmonising the European dose rate monitoring network.

Cervical cord and ventricle affection in neuromyelitis optica.

OBJECTIVES: Cervical cord involvement is common in neuromyelitis optica (NMO) and multiple sclerosis (MS), but its impact on disability in NMO has rarely been studied. Recent publications on NMO examined the periventricular system, areas of high aquaporin-4 expression, but not yet by using ventricle volumetry. PURPOSE: To compare cervical cord atrophy, ventricular widening, and supra- and infratentorial brain measures between NMO and MS, and study their impact on clinical disability. METHODS: Magnet resonance imaging-based volumetry of upper cervical cord, third and fourth lateral ventricles, grey matter, white matter, brainstem, cerebellum and clinical status of 18 NMO and 20 MS patients, was compared between the groups and with 26 healthy controls. Patterns of ventricular widening relative to healthy controls were inspected by voxel-based morphometry of the cerebrospinal fluid. RESULTS: Cervical cord atrophy was similar in NMO and MS (75.2 ± 10.0 mm2 , respectively, 76.5 ± 9.5 mm2 vs 84.1 ± 8.6 mm2 in controls).Third ventricle increase in both groups, and specific fourth ventricle widening in MS were detected. Patient groups differed in third to fourth ventricle ratio (P = 0.002). In NMO, white matter correlated inversely with the affected cord segments (P = 0.001) and with cervical cord area (P = 0.043). The disability status was explained by cervical cord area and third ventricle volume (R2 =0.524) in NMO, and by grey matter and fourth ventricle volume (R2 =0.565) in MS. CONCLUSION: Cervical cord atrophy and third ventricular enlargement are both clinically relevant in NMO. Third and fourth ventricle volumetry shows differences between NMO and MS regarding the involvement of periventricular structures.

Multicenter Validation of Mean Upper Cervical Cord Area Measurements from Head 3D T1-Weighted MR Imaging in Patients with Multiple Sclerosis.

BACKGROUND AND PURPOSE: Spinal cord atrophy is a common and clinically relevant characteristic in multiple sclerosis. We aimed to perform a multicenter validation study of mean upper cervical cord area measurements in patients with multiple sclerosis and healthy controls from head MR images and to explore the effect of gadolinium administration on mean upper cervical cord area measurements. MATERIALS AND METHODS: We recruited 97 subjects from 3 centers, including 60 patients with multiple sclerosis of different disease types and 37 healthy controls. Both cervical cord and head 3D T1-weighted images were acquired. In 11 additional patients from 1 center, head images before and after gadolinium administration and cervical cord images after gadolinium administration were acquired. The mean upper cervical cord area was compared between cervical cord and head images by using intraclass correlation coefficients (ICC) for both consistency (ICCconsist) and absolute (ICCabs) agreement. RESULTS: There was excellent agreement of mean upper cervical cord area measurements from head and cervical cord images in the entire group (ICCabs = 0.987) and across centers and disease subtypes. The mean absolute difference between the mean upper cervical cord area measured from head and cervical cord images was 2 mm(2) (2.3%). Additionally, excellent agreement was found between the mean upper cervical cord area measured from head images with and without gadolinium administration (ICCabs = 0.991) and between the cervical cord and head images with gadolinium administration (ICCabs = 0.992). CONCLUSIONS: Excellent agreement between mean upper cervical cord area measurements on head and cervical cord images was observed in this multicenter study, implying that upper cervical cord atrophy can be reliably measured from head images. Postgadolinium head or cervical cord images may also be suitable for measuring mean upper cervical cord area.

Cervical cord area is associated with infratentorial grey and white matter volume predominantly in relapsing-remitting multiple sclerosis: A study using semi-automated cord volumetry and voxel-based morphometry.

BACKGROUND AND PURPOSE: Atrophy of the brain and the upper cervical cord, which both have major impact on the severity of clinical symptoms in multiple sclerosis (MS), may be interrelated by neuraxonal degeneration. Aiming to identify possible spatially remote effects of neuraxonal brain damage on spinal cord atrophy, we studied regional and global brain volumes and the upper cervical cord area (UCCA) in a large group of MS patients and a healthy control group. METHODS: In a group of 132 MS patients (71 relapsing-remitting MS; 61 secondary progressive MS; median [range] of EDSS: 5 [0-7], respectively 6 [2-8.5] and mean±standard deviation of age/disease duration: 37±11 years/6.7±6.3 years; respectively: 49±8 years/14.5±8.0 years) and 45 healthy subjects UCCA, regional and global brain volumes, and brain lesion load were assessed. Associations between MRI results and clinical parameters in the entire cohort and differentiated according to MS-subtype were investigated using t-tests, partial correlation analyses, voxel-based morphometry and statistical parametric mapping. RESULTS: Exclusively in RRMS, a significant positive correlation of UCCA with cerebellar cortical grey matter (GM) in the vermis and with regional white matter volume in the entire brainstem, corresponding to the corticospinal tracts, was detected. Although SPMS patients were considerably more affected by disability and decrease of UCCA (RRMS:75.2±10.4 mm(2); SPMS: 66.0±11.8 mm(2),controls: 84.5±8.7mm(2)), brain grey matter (RRMS:585.8±53.6 ml; SPMS: 528.2±61.5 ml, controls: 608.7±48.1 ml) and total brain volume (RRMS:1162.9±41.8 ml; SPMS: 1117.9±51.2 ml, controls: 1194.1±19.5 ml) than RRMS patients, significant positive associations in this group were found only between UCCA and a cluster of white matter in the medulla, but not in grey matter. CONCLUSION: Cervical cord and brain atrophy were present in both, RRMS and even more severe in SPMS. Still, spatial associations between cervical cord area and remote cerebellar and brainstem volume, possibly driven by neuraxonal degeneration, were detected mostly in RRMS patients with predominantly short disease durations. Future longitudinal studies may elucidate the interplay between affection of spinal cord and infratentorial structures in MS, and contribute to the understanding of the conversion processes from relapsing-remitting to secondary progressive MS.