Biokinetic modelling of natural thorium in humans by ingestion.

The retention of naturally occurring thorium (228Th, 230Th, 232Th) in model compartments and its daily urinary and faecal excretion after acute and chronic injections and ingestions were calculated for male and female subjects of six age groups based on the current age-dependent biokinetic model for thorium (Th) recommended by the International Commission on Radiological Protection (ICRP). The results are tabulated in a database. The calculated contents of 228,230,232Th in organs or tissues using their reference concentrations in foodstuffs for the European population are compared with autopsy data. The model prediction of 232Th in whole body for a 50-year-old unexposed person is 22 mBq, 86% of that in skeleton, 9.7% in other soft tissues, 3.4% in liver, 0.7% in kidneys and 0.01% in blood. The modelling predicts lower contents of the natural Th isotopes in whole body, especially in blood compared with measured data for the unexposed public. Modelled 232Th daily urinary excretions are 5 to 10 times less than bio-assay data from the authors' own laboratory.

Potential of modern technologies for improvement of in vivo calibration.

In the frame of IDEA project, a research programme has been carried out to study the potential of the reconstruction of numerical anthropomorphic phantoms based on personal physiological data obtained by computed tomography (CT) and Magnetic Resonance Imaging (MRI) for calibration in in vivo monitoring. As a result, new procedures have been developed taking advantage of recent progress in image processing codes that allow, after scanning and rapidly reconstructing a realistic voxel phantom, to convert the whole measurement geometry into computer file to be used on line for MCNP (Monte Carlo N-Particule code) calculations. The present paper overviews the major abilities of the OEDIPE software studies made in the frame of the IDEA project, on the examples of calibration for lung monitoring as well as whole body counting of a real patient.

Overview of active personal dosemeters for individual monitoring in the European Union.

In 2001, the European Radiation Dosimetry Group, EURADOS, started a working group on 'Harmonisation of Individual Monitoring in Europe and the Dissemination of Information on New Techniques in this Field'. Within this group, one of the projects consisted of analysing the status of active personal dosemeters (APDs) in Europe. This paper reviews the regulatory requirements for APDs in 15 EU member states and summarises the main characteristics of commercial and new developments in this field. In particular, it focuses on the comparison of APD performance and standard passive dosimetry systems. Based on this information, an evaluation is initiated to establish why several countries are reluctant to accept APDs for dose records.

Improvements in routine internal monitoring--an overview of the IDEA project.

The IDEA project aimed to improve the assessment of incorporated radionuclides through developments of advanced in vivo and bioassay monitoring techniques and making use of such enhancements for improvements in routine monitoring. Many of these findings are not new in the sense that they are being already employed in advanced laboratories or for specialised applications. The primary goal was to categorise those new developments regarding their potential and eligibility for the routine monitoring community. Attention has been given to in vivo monitoring techniques with respect to detector characteristics and measurement geometry to improve measurement efficiency with special attention to low energy gamma emitters. Calibration-specifically supported by or through methods of numerical simulation-have been carefully analysed to reduce overall measurement uncertainties and explore ways to accommodate the individual variability based on characteristic features of a given person. For bioassay measurements at low detection limits, inductively coupled plasma mass spectroscopy offers significant advantages both in accuracy, speed, and sample preparation. Specifically, the determination of U and Th in urine and the associated models have been investigated. Finally, the scientific achievements have been analysed regarding their potential to offer benefits for routine monitoring. These findings will be presented in greater detail in other papers at this conference, whereas this paper intends to give an overview and put both the scientific achievements as well as the derived benefits into perspective.

Practical implications of procedures developed in IDEA project--comparison with traditional methods.

The idea of the IDEA project aimed to improve assessment of incorporated radionuclides through developments of more reliable and possibly faster in vivo and bioassay monitoring techniques and making use of such enhancements for improvements in routine monitoring. In direct in vivo monitoring technique the optimum choice of the detectors to be applied for different monitoring tasks has been investigated in terms of material, size and background in order to improve conditions namely to increase counting efficiency and reduce background. Detailed studies have been performed to investigate the manifold advantageous applications and capabilities of numerical simulation method for the calibration and optimisation of in vivo counting systems. This calibration method can be advantageously applied especially in the measurement of low-energy photon emitting radionuclides, where individual variability is a significant source of uncertainty. In bioassay measurements the use of inductively coupled plasma mass spectrometry (ICP-MS) can improve considerably both the measurement speed and the lower limit of detection currently achievable with alpha spectrometry for long-lived radionuclides. The work carried out in this project provided detailed guidelines for optimum performance of the technique of ICP-MS applied mainly for the determination of uranium and thorium nuclides in the urine including sampling procedure, operational parameters of the instruments and interpretation of the measured data. The paper demonstrates the main advantages of investigated techniques in comparison with the performances of methods commonly applied in routine monitoring practice.

Implementation of bioassay methods to improve assessment of incorporated radionuclides.

The present work which was carried out in the framework of an EU project (IDEA: Internal Dosimetry-Enhancements in Application; Contract Number: FIKR CT2001 00164) shall provide commonly acceptable guidelines for optimum performance of ICP-MS measurements with focus on urinary measurements of uranium, thorium and actinides. From the results of this work it is recommended that, whenever feasible, 24 h urine sampling should be conducted to avoid large uncertainties in the quantitation of daily urinary excretion values. For storage, urine samples should be acidified and kept frozen before analysis. Measurement of total uranium in urine by ICP-MS at physiological levels (<10 ng.l(-1)) requires no sample preparation besides UV photolysis and/or dilution. For the measurement of thorium in urine by ICP-MS, it can be concluded, that salt removal from the urine samples is not recommended. For the measurement of actinides in urine it is shown that ICP-MS is well-suited and a good alternative to alpha-spectrometry for isotopes with T1/2>5x10(4) years. In general, ICP-MS measurements are an easy, fast and cost-saving methodology. New improved measuring techniques (HR-SF-ICP-MS) with detection limits in urine of 150 pg.l(-1) (1.9 microBq.l(-1)) for 238U, 30 pg.l(-1) (2.4 microBq.l(-1)) for 235U and 100 pg.l(-1) (0.4 microBq.l(-1)) for (232)Th, respectively, meet all necessary requirements. This method should therefore become the routine technique for incorporation monitoring of workers and of members of the general public, in particular for uranium contamination.

Aspects of harmonisation of individual monitoring for external radiation in Europe: conclusions of a EURADOS action.

Following the publication of the EU Council Directive 96/29, EURADOS coordinated two working groups (WGs) for promoting the process of harmonisation on individual monitoring of occupationally exposed persons in Europe. An overview of the major findings of the second WG is presented. Information on the technical and quality standards and on the accreditation and approval procedures has been compiled. The catalogue of dosimetric services has been updated and extended. An overview of national regulations and standards for protection from radon and other natural sources in workplaces has been made, attempting to combine the results from individual monitoring for external, internal and workplace monitoring. A first status description of the active personal dosemeters, including legislative and technical information, and their implementation has been made. The importance of practical factors on the uncertainty in the dose measurement has been estimated. Even if a big progress has been made towards harmonisation, there is still work to be done.

Risk factors for postoperative wound infections and prolonged hospitalization after ventral/incisional hernia repair.

PURPOSE: The purpose of this study was to identify predictive factors for postoperative surgical site infections (SSIs), and increased length of hospital stay (LOS) after ventral/incisional hernia repair (VIHR) using multi-center, prospectively collected data. STUDY DESIGN: Cases of VIHR from 2009 to 2010 were identified in the American College of Surgeons National Surgical Quality Improvement Program database. Using logistic regression, a prediction model utilizing 41 variables was developed to identify risk factors for postoperative SSIs, and increased LOS. Separate analyses were carried out for reducible and incarcerated/strangulated cases. RESULTS: A total of 28,269 cases of VIHR were identified, 25,172 of which met inclusion criteria. 18,263 cases were reducible hernias, and 6,909 cases were incarcerated/strangulated hernias. Our prediction model demonstrated that body mass index ≥30 kg/m(2), smoking, American Society of Anesthesiology (ASA) class 3, open surgical approach, prolonged operative times, and inpatient admission following VIHR were significant predictors of postoperative SSIs. In addition, risk factors associated with prolonged LOS included older age, African American ethnicity, history of alcohol abuse, ASA classes 3 and 4, poor functional status, operation within the last 30 days of the index operation, history of chronic obstructive pulmonary disease, congestive heart failure, and bleeding disorder, as well as open surgical approach, non-involvement of residents, prolonged operative times, recurrent hernia, emergency operation, and low preoperative serum albumin level. CONCLUSIONS: Obesity and smoking are modifiable risk factors for SSIs after VIHR, whereas a low serum albumin level is a modifiable risk factor for prolonged LOS. Addressing factors preoperatively might improve patient outcome, and reduce health care expenditures associated with VIHR. In addition, if feasible, the laparoscopic approach should be strongly considered.

Necrotizing soft tissue infections: a surgical disease.

Despite advances in antibiotics and infection control practices necrotizing fasciitis is still a potentially lethal disease. We reviewed 37 patients with necrotizing fasciitis to identify prognostic factors indicating outcome. Overall mortality was 24 per cent. Mortality was significantly increased for elderly patients. Solid-organ transplant recipients also represented a subset of patients with increased mortality. Most infections were polymicrobial. There was no Clostridium perfringens cultured. Rapid diagnosis and treatment with surgical debridement remains the cornerstone of therapy.

Potential risk factors for deep venous thrombosis in burn patients.

Risk factors and prophylaxis for prevention of deep venous thrombosis (DVT) and pulmonary embolism remain controversial in burn patients. From January 1996 through June 1999, we reviewed all adult burn patients admitted to our burn center with the in-hospital diagnosis of DVT and assessed each affected patient for DVT risk factors. There were 8 symptomatic DVTs and 2 pulmonary embolisms detected in 327 adult burn patients (2.4% incidence). No DVT patient had the risk factors of morbid obesity, previous DVT, congestive heart failure, or neoplastic disease. One patient was older than 65 years. All of the DVTs occurred in veins draining a burned extremity. Seven of 8 patients had burn wound infections as complications. Burns on the extremity developing the DVT as well as the diagnosis of a burn wound infection were significant risk factors for DVT formation. These findings prompt us to consider routine screening for DVT in burn patients with these risk factors.

Venous thrombosis incidence in burn patients: preliminary results of a prospective study.

There are few prospective data on the incidence of deep venous thrombosis (DVT) in burn patients. In an on-going prospective study, hospitalized burn patients 18 years or older with an expected hospital length of stay more than 72 hours were imaged with baseline venous duplex ultrasound of all extremities within the first 48 hours after admission and weekly until discharge. Patient demographics and clinical risk factors for DVT were assessed. At the time of submission, 40 patients met screening criteria, and 30 were enrolled. Ultrasound diagnosed seven patients with 11 acute DVT for an incidence of 23%. One pulmonary embolism was documented. DVT patients had a mean age of 49 +/- 23 years with an average TBSA burn of 15 +/- 4% compared with those without thrombosis with a mean age of 44 +/- 17 years (P = NS) and TBSA burn of 18 +/- 25% (P = NS). There were no statistically significant differences for DVT patients in terms of age, number of central line days, hospital length of stay, or TBSA burned. Given the preliminary findings of this small study, we believe that all hospitalized burn patients are at risk for DVT. On-going investigation will be helpful in defining level of risk and improved prevention strategies for thromboembolic complications in burn patients.

Changes in the extracellular matrix of the vein wall--the cause of primary varicosis?

BACKGROUND: Conflicting theories on the development of primary varicosis have led to the molecular biological investigation of the vein wall or, more accurately, of the extracellular matrix. It was the aim of this study to quantify matrix expression and to compare pathological changes in the vein wall with valve-orientated staging of varicosis, in order to determine indicators of the primary cause of varicosis. MATERIALS AND METHODS: Three hundred seventy-two tissue specimens of greater saphenous veins were obtained from 17 patients with varicosities and categorised according to Hach stage and procurement site. The specimens were compared with 36 specimens collected from six patients without varicosities, incubated with fluorescence-stained antibodies for collagen 4, laminin, fibronectin and tenascin prior to being assessed with confocal laser scan microscopy. In addition, 22 vein specimens (16 varicose, 6 normal veins) serving as negative controls were investigated. RESULTS: Image analysis and statistical evaluation showed that compared with normal veins, varicose veins are associated with a significant increase in matrix protein expression for collagen 4, laminin and tenascin. A trend towards an increase in matrix expression was further observed for fibronectin. There was, however, no difference between varicose veins and clinically healthy vein segments inferior to a varicose segment. CONCLUSION: If the findings of the present investigation can be confirmed by other studies, alterations in the vein wall may be regarded as the primary cause of varicosis and valvular insufficiency as the result of these changes.

[Fascia dehiscence--cause and prognosis]. / Die Fasciendehiscenz--Ursache und Prognose.

During a period of 5 years, 4476 interventions in abdominal surgery were prospectively analyzed. The incidence of fascial dehiscence was 0.7% (n = 30). Seventeen of these patients underwent surgery on account of intraabdominal infection (total incidence of intraabdominal infection 4.4%). Fascial dehiscence developed in 22 out of 30 patients (73%) after emergency surgery. All of them had to be operated out of routine surgical schedule with the exception of four patients. Using multivariate stepwise logistic regression analysis, main determinant factors in fascial dehiscence were the ASA score (p = 0.0001), reflecting the severity of primary or concomitant diseases, and wound infection (p = 0.0075), mostly due to intraabdominal contaminations. Fascial dehiscence was associated significantly with a higher morbidity, reflected by longer inpatient management. Nevertheless, the overall lethality of 20% was associated to serious primary or concomitant diseases. Therefore, the results emphasize the significance of diligent preoperative work-up. Adequate treatment for concomitant disorders should be performed preoperatively, whenever possible even in emergency surgery.

[Experiences with various scores in evaluating the prognosis of postoperative intensive care patients]. / Erfahrungen mit verschiedenen Scores zur Beurteilung der Prognose bei postoperative Intensivtherapiepatienten.

At the intensive care unit of the Clinic for General and Abdominal Surgery and the Clinic for Emergency Medicine in Mainz, various scores (APACHE II score, HIS, TISS, ASA score), laboratory parameters (serum creatinine, white blood count, platelet count, serum lactate, serum elastase, Quick), body temperature, age as well as presence of a malignant underlying or associated disease, were analyzed with regard to their prognostic significance in 169 postoperative admissions. Apart from univariate analysis (Wilcoxon test) and a multivariate analysis (stepwise logistic regression), the value of the scores is demonstrated on the basis of sensitivity, specificity and correctness, as well as the behaviour of the scores at certain decisive points (cut-off point). Of the parameters studied, the APACHE II score, the HISS, the TISS and serum lactate had a significant influence on the outcome of intensive care. Examination of these scores and serum lactate at different decisive points (false-positive rate of 0%, point of highest sensitivity, point of maximal correctness) showed the TISS to have the best results. The TISS has, with a sensitivity of 100%, a false-positive rate of 41%, compared with 55% for the HIS, 81% for the APACHE II and 82% for serum lactate. With a false-positive rate of 0%, the sensitivity of the TISS is only 10%, of APACHE II and serum lactate 5% and of the HIS 0%. The patient with the highest HIS score has survived. The serum lactate level is another good parameter that is a lot easier to determine and is comparable to the APACHE II score and the HIS in its prognostic significance. Thus, scores are suitable for the estimation of the prognosis in certain patient groups. However, insufficient discrimination between patients who die and patients who survive means that these parameters cannot be used for individual therapeutic decisions in severely ill patients. The decision between the institution or cessation of intensive care is made by the physician or the medical team. Due to the use of prognostic factors, such as scores, decision-making can be objectified and therefore made easier.

[Primary varicose veins--changes in the venous wall and elastic behavior]. / Primäre Varicosis--Veränderungen in der Venenwand und im elastischen Verhalten.

The aetiology of varicosis is still unclear. Investigation of changes in normal veins which result in the formation of varicosis led to examination of elastic properties and histomorphological alterations in the region of the extracellular matrix in the vessel wall of the long saphenous vein in normal and varicose veins. The rigidity of varicose veins was higher than that of normal veins; there was no difference between the varicose vein above a competent valve and the "normal" vein below this competent valve. The matrix proteins demonstrated an increase in total fibres, whereas the elastic fibres were reduced and fragmented, explained the rigidity of varices. These results suggest that the role of the venous valves in the development of varicose veins is secondary to changes of the vein wall.

[Differentiated surgical therapy of esophageal carcinoma]. / Differenzierte chirurgische Therapie des Oesophaguscarcinoms.

Between September 1985 and December 1993 280 patients suffering from esophageal cancer underwent treatment at the department of general and abdominal surgery at the University of Mainz. Of the 167 patients operated, 152 patients had an esophageal resection performed in 113 cases as abdominothoracic resection and in 39 cases via the transmediastinal approach. 104 patients were curative resected (R0). Recurrence-free and total survival were correlated to the extent of the mediastinal lymph node dissection supposing comparable operative stress. The mean recurrence-free and the mean total survival after abdominothoracic resection with 2-field lymph node dissection were 42.4 months resp. 47.3 vs. 18.9 months resp. 25.2 months after transmediastinal resection (p = 0.015 and p = 0.035). We suggest a differentiated surgical approach concerning abdominothoracic resection with 2-field lymph node dissection for limited tumor size (pT1-3 pN0-1 M0), if the operative risk is tolerable. The transmediastinal resection appears to be only enough radical in cases with early tumor stages (UICC 0-I) and also is advantageous for risk patients with simultaneously more advanced tumor (palliative resection), because of the lower operative stress.

[Endosonography of esophageal cancer. Results of a clinical study and in vitro analysis]. / Endosonographie beim Oesophaguscarcinom. Ergebnisse einer klinischen Untersuchung und einer In-vitro-Analyse.

From April 1989 to June 1991 63 patients with esophageal cancer were investigated by endosonography with the object of ascertaining the depth of intrathoracic tumor infiltration and lymphnode involvement. The sensitivity in diagnosing tumor infiltration amount to 0.74; the sensitivity for involvement of regional lymphnode was 0.84, specificity 0.44. In an in-vitro analysis endosonographic criteria for the assessment of regional lymphnodes are proved. Echogenic structure seems not to be a valuable criterium.

[Image analysis of DNA cytometry for assessing prognosis after resection of esophageal cancer]. / Bildanalytische DNS-Cytometrie zur Prognosebeurteilung nach Oesophaguscarcinomresektion.

Esophagus cancer is a heterogeneous disease with considerable differences in malignant behaviour. Some relevant factors for prognosis are known. In this study we analyzed DNA-ploidy as a potential prognostic parameter in esophagus carcinoma. Paraffin embedded histological material from 50 patients with an esophagus cancer, obtained by resection, were selected for analysis. Tumor areas within the paraffin material were identified by HE-stained reference sections. One 50 microns section was dewaxed, rehydrated and mechanically and enzymatically treated to a suspension of 10,000 cells/ml. 1 ml of the suspension, containing bare nuclei with small rests of cytoplasma was centrifuged on glass slides. The fixed nuclei were air-dried and stained by Feulgen-SITS technique, which allows quantitative measurement of DNA. The DNA analysis was carried out with a computer-controlled single cell cytophotometry (Leytas 2, Leitz, Wetzlar). In contrast to the flow cytometry with image cytometry only tumors cells were measured. Overlapping nuclei, dirt and other artefacts as well as inflammatory cells were efficiently eliminated. With the DNA image cytometry we could differentiate between diploid and hypotriploid, hypertriploid aneuploid tumors. Best prognosis had diploid and hypotriploid tumors, the worst hypertriploid carcinomas. In the multivariate analysis the DNA-content of the tumor cells in esophagus cancer was the only prognostic parameter. DNA-content of tumor cells may become considerably clinical relevant in esophagus cancer for the decision to perform a resection or palliative treatment. In patients with hypertriploid tumors an adjuvant oncological therapy may increase the prognosis.

A three si detector system for personnel neutron dosimetry developed by means of Monte Carlo simulation calculations.

The aim of this study was the development of an electronic detection system for personnel neutron dosimetry. Converter type silicon detectors were used for neutron detection. Measurements to obtain pulse height distributions were performed in neutron fields in the energy range from thermal to 14.8 MeV. They were compared with pulse height distributions calculated by means of Monte Carlo simulation programs, and their shapes and total count responses agreed very well. Based on these calculations a three-detector system for the measurement of the individual dose equivalent, Hp(10), was developed. Response functions of the system were calculated, and their dependence on angles from 0 degrees to 75 degrees was investigated. The detector system was exposed in several neutron fields and the agreement of the determined dose values with the reference dose values (0.1 mSv to 6 mSv) was better than a factor of 2, even for quasi-monoenergetic neutrons, and for angles in the range of 0 degrees, 30 degrees and 60 degrees. The detector system should be able to measure a dose range down to 10 microSv depending on the neutron energy.

Developments in internal monitoring techniques.

In an effort to increase accuracy and speed, improve detection limits and reduce uncertainties in internal dosimetry, laboratories have developed improved or new internal monitoring techniques in both in vivo measurements and bioassay analyses. Most of these techniques have not yet entered routine monitoring programmes. This paper intends to summarise these new techniques, show their potential improvements compared to the currently employed monitoring routines and discuss the main aspects of the EC-funded IDEA project, which aims at a comprehensive assessment of these techniques and the enhancements necessary to bring them to broader acceptance in the routine monitoring community.