[en] Lead aprons are used in medical facilities to protect workers and patients from unnecessary x-ray radiation exposure from diagnostic radiology procedures. A lead (or lead equivalent) apron is a protective garment which is designed to shield the body from harmful radiation, usually in the context of medical imaging. Both patients and medical personnel utilize lead aprons, which are customized for a wide range of usages. As is the case with many protective garments, it is important to remember that a lead apron is only effective when it is worn properly, matched with the appropriate radiation energy and is used in a safe and regularly inspected environment and also need stored properly. They should not be folded or thrown on the floor since it may produce creases that develop into breaks in the protective barrier. The integrity of lead aprons should be assessed annually. For reasons of weight, lead aprons generally have shielding equivalence equal to a 0.25 to 0.50 mm lead barrier and will only attenuate the radiation. Lead aprons absorb 90 % to 95 % of scattered radiation that reaches them. The main purpose of this study is to determine the radiation attenuation properties of different material lead apron against an X-ray beam in the diagnostic energy range (80 & 100 kVp) by employing an appropriate procedure. The shielding effectiveness of lead aprons was determined by performing simple transmission experiments. The results of evaluation of the effectiveness various type of lead apron with different energy range test will be presented in brief. (author)

[en] Aim of study: In this study, both the direct and indirect methods by conditional maximum likelihood (CML) and moments for fitting Johnson’s SBB were evaluated. To date, Johnson’s SBB has been fitted by either indirect (two-stage) method using well-known procedures for the marginal diameter and heights, or direct methods, where all parameters are estimated at once. Application of bivariate Johnson’s SBB for predicting height and improving volume estimation requires a suitable fitting method. Area of study: E. globulus, P. pinaster and P. radiata stands in northwest Spain. Material and methods: The data set comprised of 308, 184 and 96 permanent sample plots (PSPs) from the aforementioned species. The suitability of the method was evaluated based on height and volume prediction. Indices including coefficient of determination (R2), root mean square Error (RMSE), model efficiency (MEF), Bayesian Information Criterion (BIC) and Hannan-Quinn Criterion (HQC) were used to assess the model predictions. Significant difference between observed and predicted tree height and volumes were tested using paired sample t-test at 5% level for each plot by species. Main results: The indirect method by CML was the most suitable method for height and volume prediction in the three species. The R2 and RMSE for height prediction ranged from 0.994 – 0.820 and 1.454 – 1.676, respectively. The percentage of plot in which the observed and predicted heights were significant was 0.32%. The direct method was the least performed method especially for height prediction in E. globulus. Research highlights: The indirect (two-stage) method, especially by conditional maximum likelihood, was the most suitable method for the bivariate Johnson’s SBB distribution.

[en] Aim: to test whether image processing methods are suitable for detecting differences in the image quality of digital mammography units and whether the methods are more sensitive than visual test methods like the evaluation of CDMAM test images. Methods: test images according to PAS 1054 were acquired with CR and DR systems and analyzed automatically. Only parameters were used that are obligatory for calculating the detective quantum efficiency (DQE), the noise power spectrum (NPS), the spatial resolution (MTF, modulation transfer function), and the averaged glandular dose (AGD). The derived value, the NEQ index, is linked to the noise equivalent quanta (NEQ). Additionally CDMAM test images were acquired and evaluated at one CR and one DR system. Results:0e accuracy of the evaluated values is in the range below of 2%. The accuracy requirements are fulfilled to establish values for detecting changes in image quality related to changes in dose no greater than one exposure value. If a visual evaluation of test images is used, a significant difference in image quality can only be detected when the dose is doubled. Conclusion: a method is proposed for establishing dose-correlated tolerances for values used in constancy and acceptance tests independently of the type of mammography unit (CR and DR systems). A method which abstains from visual tests for establishing the performance of digital mammography units could be used in acceptance tests. (orig.)

No abstract available

[en] More than 50% of cancer patients survive for more than 5 years, owing to modern and effective treatment. Therefore, long-term sequelae of treatment are more frequently seen than in the past. Such effects on normal tissue may both mimic and obscure tumor recurrences. Besides the direct consequences of surgery, tissue damage due to radiation or chemotherapy frequently cause problems in differential diagnosis. Among the numerous sequelae of radiotherapy, the most prominent are disturbance of the blood-brain barrier, radiation pneumonitis, osteodystrophy and osteoradionecrosis, fatty changes of bone marrow, or increased radiodensity of breast parenchyma. Chemotherapy may cause, e.g., diffuse abnormalities of white matter, pneumonitis and lung fibrosis, cardiomyopathy, or diffuse and patchy changes in bone marrow signals in MRI. The most devastating long-term complications are secondary cancers and leukemia induced by both radiotherapy and chemotherapy. (orig.)

[en] The content of the six chapters of the WHO Handbook on Indoor Radon is briefly sketched, and an evaluating comment is given on some points which leave room for interpretation or are disputed. (orig.)

[en] Purpose: The aim of this study was to identify and evaluate the work-related satisfaction of radiologists and its influencing factors in Germany. Materials and Methods: For this purpose an invitational letter for an online opinion survey was sent to all member physicians of the Deutsche Roentgengesellschaft in 2008. 1200 questionnaires were completed (response rate 21 %) and evaluated statistically. Results: 81.7 % of radiologists declared themselves as being 'very' or 'rather satisfied'. The level of satisfaction was largely independent of age, gender, status, salary or family status. It increased over the last 5 years for 37.5 % of participants and decreased for 24.8 %. Nevertheless, 72 % of respondents indicated that they would not choose to specialize in radiology again. The main reason given was the workload. 65.6 % deemed it to be 'considerably' or 'rather too high'. Concomitantly, more than 70 % of respondents indicated that the workload had increased 'a lot' or 'rather'. Further reasons for not wanting to select the radiological profession again were 'unfavorable working hours' and 'unsatisfactory career perspectives'. Conclusion: The job satisfaction of radiologists in Germany is generally very high in spite of the perception of an extensive and frequently increasing workload. The high workload was the dominant factor against a renewed selection of the field of radiology. These data have to be interpreted in light of the current lack of residents and trained radiologists in Germany to counteract the trend toward emigration. (orig.)

[en] Purpose: Evaluation of 2 'fast' software tools, a biplane area-length method, and a new automatic 'shape tracking' method, for the calculation of left ventricle volumes (end-diastolic volume EDV, end-systolic volume ESV, stroke volume SV) and ejection fraction (EF) in retrospectively ECG-gated multidetector computed tomography. Materials and Methods: 60 contrast-enhanced cardiac CT datasets (16 x 0.75 mm collimation, normal dose: 120 - 140 kV, 400 - 500 mAs_eff [n = 44], low dose 120 kV, 100 mAs_eff [n = 16]) were acquired from eight intubated healthy pigs on different days. Images were reconstructed with a slice thickness and increment of 2 mm every 10 % of the cardiac cycle. The LV function was evaluated via the common short axis method as the reference method, the biplane area-length method, and the automatic 'shape tracking' method. In the latter a three-dimensional triangulated deformable surface model was used to segment the endocardial border of the left ventricle and to track its motion through the cardiac phases. The results were compared using the Bland-Altman-plot, the correlation coefficient, and the Wilcoxon test. Results: All 60 data sets could be evaluated with all three methods. Good correlations were found for left ventricular functional parameters for all data sets, the normal dose (ND), and low dose (LD) data sets between 0.65 and 0.89 for the 'shape tracking' method and between 0.7 and 0.87 for the area-length method. The 'shape tracking' method showed a mean overestimation of the EDV of 3.1 (LD, p 0.38) to 4.3 ml (ND, p < 0.05), the SV of 4.0 (LD, p = 0.08) to 4.9 ml (ND, p < 0.05) and the EF of 1.3 (LD, p = 0.16) to 2.0 % (ND, p < 0.05). The EDV was underestimated between 0.3 (LD, p = 0.7) and 1.1 ml (ND, p = 0.08). The area-length method showed an overestimation of the EDV (6.6 to 6.7 ml [p < 0.05]), the SV (5.9 to 8.4 ml [p < 0.05]), the EF (1.2 to 3.0 % [p < 0.05]) and the normal dose ESV (0.6 ml [p = 0.74]). The low dose ESV was underestimated (1.3 ml [p = 0.21]). (orig.)

[en] Purpose: Radiological-morphological response evaluation plays a major role in oncological therapy and studies for approval. Specific criteria have been developed for some tumor entities and chemotherapeutics. Application, limitations and definitions of the most frequently used criteria for tumor response evaluation will be presented. Materials and Methods: Review based on a selective literature research. Results: In clinical oncological therapy studies, WHO and RECIST are the most frequently used criteria to evaluate morphological therapy response. RECIST criteria have been modified recently, especially with respect to the evaluation of lymph nodes, and were published as RECIST 1.1 in 2009. All criteria were originally developed and defined to review clinical multicenter trials for approval. Using these criteria in a clinical situation, certain limitations have to be considered. To evaluate response, a baseline scan before therapy start is mandatory. Special tumor response criteria have been defined for some certain tumor entities. Oncologists and radiologists should define in advance which criteria are used before starting therapy. Conclusion: The use of defined criteria is very important in oncology response evaluation. In-depth knowledge of the criteria and their limits is required for correct usage. (orig.)

[en] The purpose of study was to develop a computer-simulated liver phantom for hepatic CT studies. A computer-simulated liver phantom was mathematically constructed on a computer workstation. The computer-simulated phantom was calibrated using real CT images acquired by an actual four-detector CT. We added an inhomogeneous texture to the simulated liver by referring to CT images of chronically damaged human livers. The mean CT number of the simulated liver was 60 HU and we added numerous 5-to 10-mm structures with 60±10 HU/mm. To mimic liver tumors we added nodules measuring 8, 10, and 12 mm in diameter with CT numbers of 60±10, 60±15, and 60±20 HU. Five radiologists visually evaluated similarity of the texture of the computer-simulated liver phantom and a real human liver to confirm the appropriateness of the virtual liver images using a five-point scale. The total score was 44 in two radiologists, and 42, 41, and 39 in one radiologist each. They evaluated that the textures of virtual liver were comparable to those of human liver. Our computer-simulated liver phantom is a promising tool for the evaluation of the image quality and diagnostic performance of hepatic CT imaging. (orig.)