A benchmark for Monte Carlo simulations in gamma-ray spectrometry Part II: True coincidence summing correction factors.

The goal of this study is to provide a benchmark for the use of Monte Carlo simulation when applied to coincidence summing corrections. The examples are based on simple geometries: two types of germanium detectors and four kinds of sources, to mimic eight typical measurement conditions. The coincidence corrective factors are computed for four radionuclides. The exercise input files and calculation results with practical recommendations are made available for new users on a dedicated webpage.

Maladie thromboembolique veineuse chez la femme au service de cardiologie du CHU de Kati / Venous thromboembolic disease in women in the cardiology department of the Kati university hospital

Introduction : La maladie thromboembolique veineuse (MTEV) regroupe : la thrombose veineuse profonde(TVP) et l'embolie pulmonaire(EP).Ce travail a été initié pour identifier les particularités féminines si elles existent. Matériels et Méthode : il s'agissait d'étude rétrospective, descriptive réalisée dans le service de cardiologie du CHU de Kati sur une période allant du 01 janvier 2014 au 31 décembre 2021. Ont été inclues les patientes hospitalisées durant la dite période pour maladie thromboemboliqueveineuse. Les variables étudiées étaient les données sociales démographiques, les facteurs de risque, les paramètres cliniques et paracliniques, les aspects thérapeutiques et évolutifs. Résultats : Au total nous avons enregistré 68 cas de MTEV dont 40 (58,8%) femmes. Il s'agissait 12 (30%) cas de TVP, 25 (62,5%) d'EP et leur association dans 3 (7,5%) cas. La majorité (82,5%) des patientes était des femmes au foyer.Le post partum représentait 10% des cas. La probabilité clinique, selonle score de Wells était élevée chez 93% des TVP, intermédiaire pour les cas d'embolie pulmonaire avec 50%. L'angioscanner révélait que l'embolie pulmonaire était bilatérale dans 80% des cas. L'héparine et l'AVK ont été les plus utilisés. La mortalité était de 7,5%. Conclusion : les femmes sont plus victime des maladies thromboemboliques veineuses que les hommes. Le post partum est une situationparticulière chez la femme. Les récidives ne sont pas rares

Introduction: Venous thromboembolic disease (MTEV) includes: deep venous thrombosis (DVT) and pulmonary embolism (PE).This work was initiated to identify the female particularities if they exist.Materials and Method: This was a retrospective, descriptive study conductedin the cardiology department of the Kati university hospital over a period from January 01, 2014 to December 31, 2021.Patients hospitalized during the period for venousthromboembolic disease were included.The variables studied were demographic social data, risk factors, clinical and para-clinical parameters, therapeutic and evolutionary aspects. Results: In total we recorded 68 cases of MTEV of which 40 (58.8%) women. There were 12 (30%) cases of deep vein thrombosis, 25 (62.5%) cases of pulmonary embolism and their association in 3 (7.5%) cases.The majority (82.5%) of patients were housewives.Thepostpartum accounted for 10% of cases.The clinical probability according to the Wells score was high in 93% of deep vein thrombosis, intermediate for cases of pulmonary embolism with 50%.Angio-CT showed that pulmonary embolism was bilateral in 80% of cases. Heparin and anti-vitamin K were the most commonly used. Mortality was 7.5%. Conclusion: women are more victims of venous thromboembolic diseases than men. Postpartum is a special situation for women. Recurrences are not uncommon

Activity standardization of 60Co and 106Ru/106Rh by means of the TDCR method and the importance of the beta spectrum.

Atomic and nuclear data represent an important input for the accuracy of primary activity measurements based on liquid scintillation. In particular, the reliability of ß-spectrum computation has been investigated for several years through experimental and theoretical studies providing solid evidence for the need to consider the atomic effects. In the present study, the activity standardization of two ß-emitting radionuclides (60Co, 106Ru/106Rh) was carried out by means of the 4πß-γ coincidence and Triple-to-Double Coincidence Ratio (TDCR) methods. The comparison between the activity concentrations given by both primary techniques presents new evidence that a better agreement is obtained when the exchange and screening effects are included in the ß-spectra implemented in the model of light emission for TDCR measurements. A new development of a stochastic model based on Geant4 simulations for TDCR calculations is also presented.

Mapping the Posterior Ledge and Optic Foramen in Orbital Floor Blowout Fractures.

Background The posterior ledge (PL) is a vital structure that supports the implant posteriorly during orbital floor reconstruction. This study describes a technique for mapping the PL in relation to the infraorbital margin (IM) in patients with orbital floor blowout fractures. This study establishes the location of the optic foramen in relation to the PL. Methods Facial computed tomography (FCT) scans of 67 consecutive patients with isolated orbital floor blowout fractures were analyzed using Osirix. Planes of reference for orbital fractures, a standardized technique for performing measurements on FCT, was used. Viewed coronally, the orbit was divided into seven equal sagittal slices (L1 laterally to L7 medially) with reference to the midorbital plane. The distances of PL from IM and location of optic foramen were determined. Results The greatest distance to PL is found at L5 (median: 30.1 mm, range: 13.5-37.1 mm). The median and ranges for each slice are as follows: L1 (median: 0.0 mm, range: 0.0-19.9 mm), L2 (median: 0.0 mm, range: 0.0-21.5 mm), L3 (median: 15.8 mm, range: 0.0-31.7 mm), L4 (median: 26.1 mm, range: 0.0-34.0 mm), L5 (median: 30.1 mm, range: 13.5-37.1 mm), L6 (median: 29.0 mm, range: 0.0-36.3 mm), L7 (median: 20.8 mm, range: 0.0-39.2 mm). The median distance of the optic foramen from IM is 43.7 mm (range: 37.0- 49.1) at L7. Conclusion Distance to PL from IM increases medially until the L5 before decreasing. A reference map of the PL in relation to the IM and optic foramen is generated. The optic foramen is located in close proximity to the PL at the medial orbital floor. This aids in preoperative planning and intraoperative dissection.

Malnutrition among patients admitted to the subacute geriatric ward during the COVID-19 pandemic era: A cross-sectional study in a tertiary hospital in Malaysia.

BACKGROUND: Acute illness and hospitalisation detriment the nutritional status of older patients. This study aimed to describe the prevalence of malnutrition, characteristics and in-hospital outcomes associated with malnutrition, and nutritional management among patients who were admitted to the Subacute Geriatric Ward. METHODS: This is a retrospective study of older patients (age ≥ 60) who were admitted to the Subacute Geriatric Ward of Kuala Lumpur Hospital from 1 March 2021 to 31 May 2021. Malnutrition was identified using the Mini Nutritional Assessment-Short Form (MNA-SF). The in-hospital outcomes evaluated were hospital-associated complications, namely delirium, functional decline, incontinence, inpatient falls, inpatient pressure injuries, hospital-acquired infection, institutionalisation, and inpatient mortality. RESULTS: Seventy-three patients were included (mean age 74.7, female 58.9%), of which 28 (38.4%) and 27 (37.0%) were malnourished and at risk of malnutrition, respectively. Poorer nutritional status was associated with increased age, comorbidity burden, frailty, immobility, impaired basic activities of daily living, history of falls, cognitive impairment, incontinence, and arthritis. About 71.2% and 60.3% of patients were offered dietitian review and oral nutritional supplements, respectively. The in-hospital outcome rates were higher among malnourished patients, but the differences were not statistically significant. However, multiple hospital-associated complications were more common with poorer nutritional status (p = 0.018). CONCLUSION: Hospital malnutrition is prevalent among older patients, and unidentified malnutrition is not justified due to its association with multiple adverse outcomes.

[Epidemiological and clinical aspects of atrial fibrillation at the cardiology department of kati university hospital]. / Aspects epidemiologique et clinique de la fibrillation auriculaire au service de cardiologie du chu de kati.

Atrial fibrillation is the most frequent permanent rhythm disorder.Theaim of this work was to determine the epidemiological and clinical aspects of atrial fibrillation cases hospitalized in the cardiology department of the University Hospital of Kati. MATERIALS AND METHODS: We carried out a descriptive retrospective study, from January 2018 to December 2019.Patients of all ages and both sexes with clinical and EKG atrial fibrillation admitted to the department during the study period were included in the study.The variables studiedwere: socio-demographic characteristics, clinical signs, classification of atrial fibrillation, and comorbidities associated. RESULTS: A total of 52 patients were included in the studyof 203 cases hospitalized in the department, with a hospital prevalence of 25.61%, the female sex was predominant 69.23%. The main reason for consultation was heart failure syndrome (46.15%).Arterial hypertension (55.76%) was the mostassociatedcomorbidity. Permanent atrial fibrillation accounted for 63.46% of cases . CONCLUSION: Atrial fibrillation is the most frequent arrhythmia in our environment, preventive measures must be put in place for early detection and better management of comorbiditiesassociatedwith atrial fibrillation.

La fibrillation auriculaire est le trouble du rythme le plus fréquent. Le but de ce travail était de déterminer les aspects épidémiologiques et cliniques de la fibrillation atriale dans le service de cardiologie du CHU de Kati. MATÉRIELS ET MÉTHODES: Il s'agit d'une étude rétrospective descriptive menée de janvier 2018 à décembre 2019. Ont été inclus dans cette étude les patients de tout âge et des deux sexes ayant présenté une fibrillation atriale sur des critères cliniques et électrocardiographiques, admis dans le service pendant la période d'étude. Les variables étudiées étaient : les caractéristiques sociodémographiques, les signes cliniques et électriques, et les comorbidités associées. RÉSULTATS: Au total 52 patients ont été inclus dans l'étude sur 203 cas hospitalisés dans le service soit une prévalence hospitalière de 25,61%, le sexe féminin a été prédominant 69,23%. Le principal motif de consultation était le syndrome d'insuffisance cardiaque (46,15%). L'hypertension artérielle (55,76%) a été la comorbidité la plus associée. La fibrillation atriale permanente représentait 63,46% des cas. CONCLUSION: La fibrillation atriale est l'arythmie la plus fréquente dans notre milieu, des mesures préventives doivent être mise en place pour une détection précoce et une meilleure prise en charge des comorbidités associées.

[Epidemiology of Covid-19 and high blood pressure association at Mali'shospital]. / Epidemiologie de l'association Covid-19 et hypertension arterielle a l'hopital du Mali.

INTRODUCTION: High blood pressure is a major cardiovascular risk factor. Patients with cardiovascular risk factors are at risk of developing COVID-19. The objective of this study was to determine epidemiology of Covid-19 infected in patients with high blood pressure. PATIENTS AND METHOD: Descriptive cross-sectional study from April 2020 to June 2020 about patients hospitalized for Covid 19 by PCR diagnosis at the Hopital du Mali Bamako and having high blood pressure. Admission registry and patient charts were used to collect data. RESULTS: We collected 78 out of 484 in patients which mean hospital frequency of 16.11%. The mean age was 55.21 +/- 14.61 years. Sex ratio M / F was 1.36. Patients were followed for high blood pressure in 59% of cases. Medical history was ischemic heart disease in 2.6% and dilated cardiomyopathy in 2.6%. Main functional signs were cough in 41.02% and lost of taste in 11.53%. High blood pressure on admission was grade 2 in 37.2% and grade 3 in 3.8%. Treatments received were calcium channel blockers 41.02%, inhibitors of the reninangiotensinaldosterone system 16.66% and combinations 15.38%. Hospital mortality was 10.3%. There was no statistically significant difference in mortality between known hypertensive patients and de novo hypertensive patients. There was also no statistically significant difference in mortality by grade of hypertension. CONCLUSION: High blood pressure can be associated to Covid 19. Treatment is based on calcium channel blockers and reninangiotensinaldosterone system inhibitors. It has an impact on the prognosis of the disease with significant mortality.

INTRODUCTION: L'hypertension artérielle (HTA) est un facteur de risque cardiovasculaire majeur. Dans la littérature elle est fréquemment retrouvée chez les patients atteints de la COVID-19.L'objectif de cette étude est de décrire l'épidémiologie de cette association chez les patients hospitalisés pour Covid-19. PATIENTS ET MÉTHODE: L'Etude est transversale et descriptive ; elle a été réalisée sur la période du 1erAvril 2020 au 30 Juin 2020. Elle a concerné les patients hospitalisés pour Covid 19 avec un test PCR positif à l'hôpital du Mali de Bamako et ayant une HTA. Les registres d'admission et les dossiers des patients ont servi pour la collecte des données. RÉSULTATS: Nous avons colligé 78 sur 484 patients hospitalisés soit une fréquence de 16,11%. L'âge moyen était de 55,21 +/- 14,61 ans. Le sex ratio H/F était de 1,36.Les patients étaient suivis pour HTA dans 59% des cas. Les antécédents médicaux étaient la cardiopathie ischémique chez 2,6% et la cardiomyopathie dilatée chez 2,6%. Les principaux signes fonctionnels étaient la toux chez 41,02% et l'agueusie chez 11,53%. L'HTA à l'admission était de grade 2 dans 37,2% des cas et de grade 3 dans 3,8% des cas. Les traitements reçus étaient les inhibiteurs calciques 41,02%, les inhibiteurs du système rénine angiotensine aldostérone 16,66% et les associations 15,38%. La mortalité hospitalière était de 10,3%. Il n'y avait pas de différence statistiquement significative concernant la mortalité entre les patients connus hypertendus et les patients hypertendus de novo. Il n'y avait pas non plus de différence statistiquement significative concernant la mortalité selon le grade de l'HTA. CONCLUSION: l'HTA peut être associée au Covid 19. Le traitement est basé sur les inhibiteurs calciques et sur les inhibiteurs du système rénine angiotensine aldostérone. Elle a un impact sur le pronostic de la maladie avec une mortalité importante.

Integration of a vertebral fracture identification service into a fracture liaison service: a quality improvement project.

Integration of a vertebral fracture identification service into a Fracture Liaison Service is possible. Almost one-fifth of computerised tomography scans performed identified an individual with a fracture. This increase in workload needs to be considered by any FLS that wants to utilise such a service. INTRODUCTION: This service improvement project aimed to improve detection of incidental vertebral fractures on routine imaging. It embedded a vertebral fracture identification service (Optasia Medical, OM) on routine computerised tomography (CT) scans performed in this hospital as part of its Fracture Liaison Service (FLS). METHODS: The service was integrated into the hospital's CT workstream. Scans of patients aged ≥ 50 years for 3 months were prospectively retrieved, alongside their clinical history and the CT report. Fractures were identified via OM's machine learning algorithm and cross-checked by the OM radiologist. Fractures identified were then added as an addendum to the original CT report and the hospital FLS informed. The FLS made recommendations based on an agreed algorithm. RESULTS: In total, 4461 patients with CT scans were retrieved over the 3-month period of which 850 patients had vertebra fractures identified (19.1%). Only 49% had the fractures described on hospital radiology report. On average, 61 patients were identified each week with a median of two fractures. Thirty-six percent were identified by the FLS for further action and recommendations were made to either primary care or the community osteoporosis team within 3 months of fracture detection. Of the 64% not identified for further action, almost half was because the CT was part of cancer assessment or treatment. The remaining were due to a combination of only ≤ 2 mild fractures; already known to a bone health specialist; in the terminal stages of any chronic illness; significant dependency for activities of daily living; or a life expectancy of less than 12 months CONCLUSION: It was feasible to integrate a commercial vertebral fracture identification service into the daily working of a FLS. There was a significant increase in workload which needs to be considered by any future FLS planning to incorporate such a service into their clinical practice.

Measurement of the absolute gamma-ray emission intensities from the decay of 147Nd.

The 2011 Decay Data Evaluation Project (DDEP) evaluation for 147Nd includes recommended absolute emission intensities for the two main gamma-rays at 91.105 (2) keV and 531.016 (22) keV of 0.284 (18) and 0.127 (9) respectively, i.e. with uncertainties of 6.3% and 7.1%. These large uncertainties stem from inconsistencies in the published data and are unfit for modern purposes, since the production of 147Nd is used as an important neutron flux dosimeter. The LNE-LNHB has undertaken new absolute gamma-ray emission intensity measurements. The results of these measurements will be presented, along with a full uncertainty budget, and their effect on the recommended data uncertainties will be discussed.

Spectral unmixing applied to fast identification of γ-emitting radionuclides using NaI(Tl) detectors.

Spectral unmixing was investigated for fast spectroscopic identification in γ-emitter mixtures at low-statistics in the case of measurements performed to prevent illegal nuclear material trafficking or for in situ environmental analysis following a radiological or nuclear accident. For that purpose, a multiplicative update algorithm based on full-spectrum analysis was tested in the case of a 3″x3″ NaI(Tl) detector. Automatic decision-making was addressed using Monte Carlo calculations of decision thresholds and detection limits. The first results obtained with a portable instrument equipped with a 3″x3″ NaI(Tl) detector designed for the control of food samples by non-expert users following a radiological or nuclear accident, are also presented.

Nuclide++: A C++ module to include DDEP recommended radioactive decay Data in Geant4.

This article describes the Nuclide++ module developed at LNE-LNHB to simulate the decay schemes related to single or multiple radionuclides, by randomly selecting decay pathways. Written in C++, with respect of the Geant4 coding style, this module can be used transparently in Geant4-based simulation applications as an alternative to the existing Radioactive Decay Module (RDM). Nuclide++ takes advantage of the DDEP recommended data, accurate ß-emitting spectra calculation and detailed description of the atomic rearrangement. This module can be useful in many applications, especially those involving radioactive sources. The reliability of the module was verified through comparisons with a while chosen radionuclides.

A benchmark for Monte Carlo simulation in gamma-ray spectrometry.

Monte Carlo (MC) simulation is widely used in gamma-ray spectrometry, however, its implementation is not always easy and can provide erroneous results. The present action provides a benchmark for several MC software for selected cases. The examples are based on simple geometries, two types of germanium detectors and four kinds of sources, to mimic eight typical measurement conditions. The action outputs (input files and efficiency calculation results, including practical recommendations for new users) are made available on a dedicated webpage.

Activity measurements and determination of nuclear decay data of 166Ho in the MRTDosimetry project.

Holmium-166 is a high-energy ß--emitter radionuclide (~ 1.8 MeV) with a short half-life (~26.8h) that offers great potential as an alternative to 90Y for the treatment of liver cancer based on radioembolization. The possibility of quantitative Single Photon Emission Computed Tomography (SPECT) imaging of the main γ-ray emission at 80.6 keV, in addition to strong paramagnetic properties suitable for Magnetic Resonance Imaging (MRI), complement this therapeutic potential. The present paper describes the measurements carried out in three European radionuclide metrology laboratories for primary standardization of 166Ho and new determinations of X- and γ-ray photon-emission intensities in the framework of the European EMPIR project MRTDosimetry. New half-life measurements were also performed.

Standardization of 68Ge/68Ga using the 4πß-γ coincidence method based on Cherenkov counting.

In the framework of an international BIPM comparison (Bureau International des Poids et Mesures), the activity standardization of 68Ge in a solution of 68Ge/68Ga in equilibrium provided by NIST was carried out at LNHB. This exercise was organized to meet the growing interest in 68Ga as a radiopharmaceutical in nuclear medicine services (e.g. as a surrogate of 18F for PET imaging). Due to the volatility of germanium, the activity standardization of 68Ge was investigated at LNHB by means of 4πß-γ coincidence counting based on Cherenkov measurements. This technique was applied to take advantage of the Cherenkov threshold (~ 260keV in aqueous solutions) in order to prevent counting from electron-capture events associated with 68Ge disintegrations. Cherenkov counting was performed using glass and polyethylene vials and the resulting activity concentrations were compared with 4πß-γ coincidence measurements based on liquid scintillation. The efficiency-extrapolation curve obtained with Cherenkov measurements in glass vials was compared to Monte Carlo simulations based on the Geant4 code.

Tailing propensity in the ultraviolet disinfection of trickling filter and activated sludge wastewater treatment processes.

In this paper, the effect of suspended flocs on the tailing of ultraviolet (UV) disinfection kinetics of secondary effluents was examined. To achieve this goal, final effluents produced in two processes for treating wastewater; namely, a trickling filter system and an activated sludge system, were collected and their UV disinfection were compared. Tailing of the UV dose response curve was controlled by the fraction of flocs that are both culturable and UV-resistant, referred to as the 'tailing propensity'. Using this parameter, the contribution of various floc size fractions in reducing the UV disinfection efficiency of wastewater samples was quantified. Activated sludge flocs larger than 125 µm exhibited as much as 35 times greater tailing propensity than smaller flocs in the range of 20-25 µm. Within a fixed size range, the tailing propensity of flocs generated in the trickling filter system was 3 to 8 times higher than that of activated sludge flocs, and this difference increased with the floc size. A mathematical model was developed to predict the UV disinfection of secondary effluents from suspended particle size distribution data. The model showed good agreement with experimental results.

A radionuclide calibrator based on Cherenkov counting for activity measurements of high-energy pure ߯-emitters.

Due to their stability and reproducibility, re-entrant pressurized ionization chambers (also called radionuclide calibrators) are widely used for activity measurements in nuclear medicine services as well as in national metrology institutes to maintain reference standards. Generally, these secondary instruments yield accurate activity measurements for γ-emitting radionuclides. Ionization chambers are easy to use and thus well-adapted to guarantee the metrological traceability between national metrology institutes and end-users. However, the reproducibility of calibration factors can be significantly impaired when measuring high-energy pure ߯-emitters such as radiopharmaceuticals based on 90Y. This is because the bremsstrahlung emission contributing to the instrument response is strongly dependent on the geometry of the components surrounding the radioactive solution. The present article describes a new design based on pulse counting to address this problem. It takes advantage of Cherenkov emission resulting from Compton scattering in transparent materials. The interest of Cherenkov counting is to obtain a low-sensitivity detector that enables direct measurements of high-activity solutions (at least up to 10 GBq for 90Y-microspheres in aqueous suspensions used in nuclear medicine). A simple design based on a geometry close to an ionization chamber used at LNHB (Vinten 671 type) is described. The feasibility in terms of detection efficiencies (lower than 10-4 for 90Y solutions) of the new radionuclide calibrator is investigated by Monte Carlo calculations using the Geant4 code.

Asian venous thromboembolism guidelines: updated recommendations for the prevention of venous thromboembolism.

The Asian venous thromboembolism (VTE) prophylaxis guidelines were first published in 2012. Since its first edition, the Asian Venous Thrombosis Forum (AVTF) working group have updated the Asian VTE epidemiology and reviewed issues that were not addressed in the previous guidelines. The authors noted that the rising incidence of VTE across Asia may be attributable to aging population, dietary changes, and increasing incidence of obesity and diabetes. The new additions in the guideline include role of thrombophilia in VTE, bleeding risk in Asians, individual risk assessment, updates in the prevention of VTE in medically ill, bariatric surgery, cancer, orthopedic and trauma patients. The influence of primary thrombophilia in perioperative VTE is still unclear. The secondary risk factors, however, are similar between Asians and Caucasians. The group found no evidence of increased risk of bleeding while using pharmacological agents, including the use of novel anti-coagulants. At present, Caprini risk assessment model is widely used for individual risk assessment. Further validation of this model is needed in Asia. In medically ill patients, pharmacological agents are preferred if there is no bleeding risk. Intermittent pneumatic compression device (IPC) is recommended in patients with bleeding risk but we do not recommend using graduated compressive stockings. In bariatric patients, data on VTE is lacking in Asia. We recommend following current international guidelines. A high index of suspicion should be maintained during postbariatric surgery to detect and promptly treat portomesenteric venous thrombosis. Different cancer types have different thrombotic risks and the types of surgery influence to a large extent the overall VTE risk. Cancer patients should receive further risk assessment. In patients with higher thrombotic risk, either due to predisposing risk or concomitant surgery, low molecular weight heparin is indicated. Different countries appear to have different incidence of VTE following trauma and major orthopedic surgery. We recommend mechanical prophylaxis using IPC as the main method and additional pharmacological prophylaxis if the thrombotic risk is high. As for obstetric practice, we propose adherence to the UK Greentop guideline that is widely accepted and utilized across Asia. To improve VTE thromboprophylaxis implementation in the region, we propose that there should be better health education, establishment of hospital-based guidelines and multidisciplinary collaboration.

Investigation of the response variability of ionization chambers for the standard transfer of SIR-Spheres(®).

The present paper addresses the calibration of well-type ionization chambers (ICs) used at LNE-LNHB as standard transfer instruments to calibrate hospitals in the case of SIR-Spheres(®)(90)Y resin microspheres (Sirtex, Australia). Developed for interventional oncology, this radiopharmaceutical is directly injected in the liver for cancer treatment via a selective internal radiation therapy. The present work was carried out in the framework of the European project "Metrology for molecular radiotherapy" (MetroMRT). As commonly performed in radionuclide metrology for radiopharmaceuticals, the objective is to ensure the metrological traceability of SIR-Spheres(®) to hospitals. Preceding studies were focused on primary measurements of SIR-Spheres(®) based on the TDCR (Triple to Double Coincidence Ratio) method, applied after the dissolution of the (90)Y-labeled resin microspheres. As (90)Y is a high-energy ß(-)-emitter, the IC response strongly depends on the transport of electrons in the radioactive solution and surroundings (vial, chamber liners and materials). The variability of the IC-response due to the geometry dependence is investigated by means of measurements and Monte Carlo simulations in the case of a Vinten IC. The aim of the present study was also to propose a reliable uncertainty for ICs calibrations for the standard transfer of SIR-Spheres(®) to hospitals.

Real-time radionuclide identification in γ-emitter mixtures based on spiking neural network.

Portal radiation monitors dedicated to the prevention of illegal traffic of nuclear materials at international borders need to deliver as fast as possible a radionuclide identification of a potential radiological threat. Spectrometry techniques applied to identify the radionuclides contributing to γ-emitter mixtures are usually performed using off-line spectrum analysis. As an alternative to these usual methods, a real-time processing based on an artificial neural network and Bayes' rule is proposed for fast radionuclide identification. The validation of this real-time approach was carried out using γ-emitter spectra ((241)Am, (133)Ba, (207)Bi, (60)Co, (137)Cs) obtained with a high-efficiency well-type NaI(Tl). The first tests showed that the proposed algorithm enables a fast identification of each γ-emitting radionuclide using the information given by the whole spectrum. Based on an iterative process, the on-line analysis only needs low-statistics spectra without energy calibration to identify the nature of a radiological threat.