Search

High purity germanium (HPGe) detectors are deployed globally for gamma-radiation spectroscopy due to their superior energy resolution. In this work, the essential characteristics of n and p-type HPGe detectors, such as energy resolution, efficiency, minimum detectable activity (MDA), and peak shape were studied for the purpose of characterization and performance optimization. The results are obtained for various source-detector configurations in a wide energy range of 40–1408 keV using gamma sources, such as 109Cd, 57Co, 137Cs, 54Mn, 65Zn, 60Co, and 152Eu. Scanning (distance, lateral, and radial) of the detectors was performed using different gamma sources to understand the orientation of the crystal with its active volume and counting efficiency and to characterize the geometry in detail. The ambient background around the n-type HPGe was reduced using Pb-shielding. As a result, an 85.85% suppression was observed in the mean integral window of 40–2700 keV. The characterization and performance tests of the detectors convincingly suggest that both the detectors can be deployed for environmental radioactivity explorations. [ABSTRACT FROM AUTHOR]

The ability to formulate maps of minimum detectable activities (MDAs) that describe the sensitivity of an ad hoc measurement that used one or more freely moving radiation detector systems would be significantly beneficial for the conduct and understanding of many radiological search activities. In a real-time scenario with a free-moving detector system, an MDA map can provide useful feedback to the operator about which areas have not been searched as thoroughly as others, thereby allowing the operator to prioritize future actions. Similarly, such a calculation could be used to inform subsequent navigation decisions of autonomous platforms. Here we describe a near real-time MDA mapping approach that can be applied when searching for point sources using detected events in a spectral region of interest (ROI) while assuming a constant, unknown background rate. We show the application of this MDA mapping method to a real scenario, a survey of the interior of a small building using a handheld detector system. Repeated measurements with no sources and with 137Cs sources of different strengths yield results consistent with the estimated thresholds and MDA values; namely, that for background-only measurements no sources are seen above threshold anywhere in the scene, while when sources are present they are detected above the thresholds calculated for their locations.

A portable body counter detects internal contamination in an emergency. Monte Carlo code estimates minimum detection activity (MDA) for a portable whole-body counter. In the case of outdoor open fields, natural background radiations were simulated. This counter has a chair geometry equipped with a NaI (Tl) detector (5cm x 5cm) inside a lead shield collimator consisting of a set of lines and a continuous component with monenergistic γ sources ranging from 300 to 2000 keV at intervals of 100 keV. This data matrix is folded with the measured spectrum outside the setup to estimate the observed spectrum in the detector. We evaluated the variation of the detector flux transmitted through the lead collimator and chair shield. This was done at different lead densities and different photon energies. Computational data were used to estimate the monitoring system MDA. This method is cheaper to design and test a counter system for low-level counting of γ emitting radionuclides than experimental methods

Large areas must be rapidly screened to monitor radiation in marine environments. For this purpose, this study developed a mobile real-time gamma-ray measurement system for shipboard use and evaluated its performance. The system was developed to measure engine or generator cooling water by installing a canister inside the ship. The minimum detectable activity of the system is about 0.8 Bq/L for a 60 s measurement period, and real-time data transmission and remote control are possible. The system was tested in the field and is currently being installed and operated on ships in service. Such a ship-based real-time gamma-radiation measurement system is suitable for a wide range of marine radiation surveillance applications and is expected to be rapidly deployed.

In arid regions, the tritium concentration in groundwater is typically very low and often falls below the minimum detectable activity (MDA) of the conventional liquid scintillation counter (LSC). Therefore, to measure the tritium activity concentration, it is necessary to lower the detection limit so that the scintillation counter can detect it. In the present study, several methods are discussed which are effective at lowering the detectable activity of tritium. One of these methods is to enrich the tritium activity concentration by ten- to fortyfold of the initial concentration of the tritium. Twelve spiked samples with known amounts of tritium, five with high concentrations and seven with low concentrations, were enriched by the electrolysis process. The results indicated that enriching the tritium levels in groundwater lowers the MDA value. Other methods are minimizing background radiation using low-background materials for sample containers, increasing the measurement efficiency of the scintillation counter and counting time, and shielding the sample from environmental radiation using the shutter option in LSC. Moreover, reducing the number of interfering contaminants in the sample can lower the uncertainty in measuring the tritium concentration in the water sample, which is beneficial for detecting low-level tritium in water to ensure public health and safety.

To achieve permanent disposal of radioactive waste drums, the radionuclides analysis process is essential. A variety of waste types are generated through the operation of nuclear facilities, with dry active waste being the most abundant. To perform radionuclides analysis, sample pre-treatment technology is required to transform solid samples into solutions. In this study, we developed a dry ashing-microwave digestion method and secured the reliability of the analysis results through a validity evaluation. Additionally, we conducted a comparative analysis of the radioactivity of 94Nb nuclides with and without the chemical separation process, which reduced the minimum detectable activity level by more than 65-fold for a certain sample. [ABSTRACT FROM AUTHOR]

Radionuclide verification is one of the four monitoring technologies used in International Monitoring System of Comprehensive Nuclear-Test-Ban Treaty (CTBT). The activity of radionuclides concerned by CTBT generally performs at the low-level. An anti-cosmic ray γ spectrometer system with a HPGe detector was developed by using a combination of active and passive shielding techniques in order to improve the detection sensitivity and reduce the affections of background. By adjusting the system with a delay time and testing anti-coincidence count loss correction, compared with the original γ spectrum, the integral background in the energy range of 15-2 700 keV is reduced by a factor of 8. The detection sensitivity is greatly improved by using the anti-coincidence method. For 140Ba, the minimum detectable activity (MDA) is 10 mBq by using the anti-cosmic ray γ spectrometer for 7 d measurement, which meets the technical requirements for certification of nuclide laboratory under the CTBT. It is not only of great significance for CTBT radionuclide verification, but also important for radiation environment monitoring.

Evaluating quiet stance under various conditions using nonlinear analysis may be an effective method of measuring postural control in older adults with mild cognitive impairment (MCI). However, no studies have examined the reliability of using sample entropy (SampEn) in older adults with MCI. What are the within- and between-session reliability and minimal detectable change (MDC) of a nonlinear analysis measure of postural control during quiet stance in older adults with MCI? Fourteen older adults with MCI performed static standing under four conditions, and the center of pressure signal was calculated and applied to SampEn nonlinear analysis. The within- and between-session reliability and MDC were explored. Within-session reliability was found to be fair to good and excellent (ICC = 0.527–0.960), and between-session reliability was excellent (ICC = 0.795–0.979). MDC values were less than 0.15. The between-session reliability of SampEn in all conditions demonstrates SampEn's stable performance. This method may be useful in assessing postural control in older adults with MCI, and MDC values may be helpful in detecting subtle changes in patient performance. • Within-session reliability of SampEn during standing in MCI was fair to excellent. • Between-session reliability of SampEn during standing in MCI was excellent. • SampEn is a reliable method of assessing postural control in MCI. [ABSTRACT FROM AUTHOR]

Monitoring of tritium concentration in tap water is an essential tool to determine the effective dose received from tap water. Liquid scintillation counting (LSC) is a widely used technique for determining tritium in water. Due to the very low activity of tritium in tap water, its detection requires a high-efficiency LSC with the lowest minimum detectable activity (MDA). Low-level tritium analysis in tap water were performed in two LSC models using conventional distillation techniques. The optimal conditions with the lowest MDAs were applied to determine the tritium concentration in the tap water distributed from two main sources located in the Bangkok metropolitan region: Bang Khen and Maha Sawat water treatment plants (WTPs). Twenty-six tap water samples were collected from petrol stations located around both water treatment plants. The results revealed that the amount of tritium in the tap water around the Bangkhen WTP was between 1.88-2.63 Bq/L with an average of 2.28±0.28 Bq/L, whereas those from the Maha Sawat WTP were between 2.01-2.69 Bq/L with an average of 2.44±0.26 Bq/L, which are far below the World Health Organization’s (WHO) guideline limit (10,000 Bq/L) for drinking water. The annual effective dose (AED) for infants, children and adults obtained from tap water samples around the Bangkhen WTP were 0.010, 0.014, and 0.030 µSv/year, respectively, and those from the Maha Sawat WTP were 0.011, 0.015, and 0.032 µSv/year, respectively, which are far below the WHO’s guideline limit (100 µSv/year).

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This study investigates operational modes and veto techniques using the Balqarad clover system, focusing on energy resolution parameters like Full Width at Half Maximum (FWHM) and Full Width at Tenth Maximum (FWTM). Comparing with the GAMMA-X detector, clover consistently shows lower FWHM values (e.g., 1.08 keV versus 1.45 keV for ^133 Ba), highlighting its higher precision. The clover system also achieves lower Minimum Detectable Activity (MDA) values (ranging from 1.19 to 1.56 Bq for ^60 Co and ^137 Cs in direct and addback modes), underscoring its enhanced performance compared to literature data. Practical MDA calculations using a reference soil sample reinforce the advantage of addback mode over direct mode in achieving more accurate measurements. These findings stress the critical importance of selecting the right measurement system for precise applications like radiation monitoring and nuclear safety assessments.

BackgroundLarge-area plastic scintillators are widely used in radiation monitoring. They are typically employed as gamma radiation counters through signal over-threshold detection. The value of the threshold voltage affects the detector efficiency and minimum detectable activity. When rays are incident at different positions of the large-area plastic, the photon collection efficiencies generated through collecting end pair differ, leading to differences in the detector efficiency.PurposeThis study aims to explore appropriate threshold voltage to reduce the differences and maintain a low minimum detectable activity (MDA), hence achieving high detection efficiency for large-area plastic scintillator.MethodsFirstly, an energy spectra acquisition system was designed using STM32F429 produced by STM semiconductor as the main control chip and a counter for detector efficiency testing of large-area plastic scintillator in size of 400 mm×300 mm×50 mm. Then, the reasonable threshold voltage was determined according to the background energy spectra of the large-area plastic scintillator, the energy spectrum of the 60Co and 137Cs sources at different positions of the large-area plastic scintillator with acquisition time of 3 min, and signal-amplification relationship.ResultsThe determined threshold voltage using above mentioned method for 60Co source is 93.7 mV. To achieve high detector efficiency and low MDA for the large-area plastic scintillator, the best determined threshold voltage for 60Co source is 95 mV. At this voltage, the detector efficiency for 60Co source is 22%, the MDA is 78 Bq.ConclusionsThe proposed method has reference value for large-area plastic scintillation designing and manufacturing detectors.

Nowadays, due to the threats of radioactive materials, control of border and sensitive facilities is of particular importance. For this reason, every year the International Atomic Energy Agency publish a report on the theft, loss or lack of monitoring and control on the movement of the radioactive materials in some countries. Therefore, introducing new methods to deal with such threats is essential. One of the most effective systems for detecting radioactive materials and contaminants are radioactive portal monitors. In this study, the results of performance evaluation of large plastic scintillation detectors for use in this type of monitoring systems are presented. Initially, the design and construction of detection circuits, electronic and mechanical holders were done. Then, the functional tests of the device were performed using 60Co and 137Cs sources. Finally, the minimum detectable activity using this monitoring device was determined. The results of the tests to determine the minimum detectable activity of the system showed that it can detect a 60Co source with a minimum activity of 1 µCi at a maximum distance of 100 cm and a 137Cs source with a minimum activity of 2 µCi at a maximum distance of 75 cm. Regard to the obtained results, it was found that the developed monitoring system has the ability to detect the radioactive sources with good accuracy.

The ISO 11929 standard on characteristic limits in measurements of ionizing radiation extends the concept of the detection limit, originally formalized by Currie, to incorporate the effects of uncertainties in the instrument calibration. The mathematical formulation presented in the standard is known to fail when those uncertainties are too large, however, making it unsuitable for applications where large calibration uncertainties are common. The most recent revision of the standard allows alternative calculation methods to evaluate the detection limit in such circumstances. Results from two such alternative methods are compared here: an approximation combining Gaussian treatment of counting uncertainties with a log-normal representation of the calibration uncertainties, and a numerical evaluation of a statistical modeling approach that accurately represents Poisson counting statistics and accommodates a variety of realistic distributions to describe the calibration uncertainty. Multiple choices of calibration uncertainty distribution for the statistical modeling method are demonstrated and discussed. [ABSTRACT FROM AUTHOR]

Monitoring of tritium concentration in tap water is an essential tool to determine the effective dose received from tap water. Liquid scintillation counting (LSC) is a widely used technique for determining tritium in water. Due to the very low activity of tritium in tap water, its detection requires a high-efficiency LSC with the lowest minimum detectable activity (MDA). Low-level tritium analysis in tap water were performed in two LSC models using conventional distillation techniques. The optimal conditions with the lowest MDAs were applied to determine the tritium concentration in the tap water distributed from two main sources located in the Bangkok metropolitan region: Bang Khen and Maha Sawat water treatment plants (WTPs). Twenty-six tap water samples were collected from petrol stations located around both water treatment plants. The results revealed that the amount of tritium in the tap water around the Bangkhen WTP was between 1.88-2.63 Bq/L with an average of 2.28±0.28 Bq/L, whereas those from the Maha Sawat WTP were between 2.01-2.69 Bq/L with an average of 2.44±0.26 Bq/L, which are far below the World Health Organization's (WHO) guideline limit (10,000 Bq/L) for drinking water. The annual effective dose (AED) for infants, children and adults obtained from tap water samples around the Bangkhen WTP were 0.010, 0.014, and 0.030 µSv/year, respectively, and those from the Maha Sawat WTP were 0.011, 0.015, and 0.032 µSv/year, respectively, which are far below the WHO's guideline limit (100 µSv/year). [ABSTRACT FROM AUTHOR]

In this work, the influence of radon and thoron progeny photons in γ-spectrometry analysis is thoroughly investigated. To this end three sampling and analysis campaigns were organized at the γ-spectrometry laboratory of Nuclear Engineering Laboratory of the National Technical University of Athens (NEL-NTUA), combining measurements of radon and its progeny via an ALPHAGUARD-ALPHAPM set up with background spectra of four germanium detectors as well as with outdoors meteorological conditions. Good statistical correlations were found between radon and its progeny with the respective photopeaks of the germanium detectors' background as well as with meteorological conditions outdoors. Additionally, in all four detectors, six consecutive 2-day background spectra were compared with each other, with their mean and with the summed 12-day background spectrum, in order to study the photopeak background fluctuation and estimate the relevant uncertainties. This study supported the decision for the most suitable background spectrum to be used in γ-spectrometry analysis. Finally, in order to investigate the effect of both radon and thoron progeny on the MDA of typical radionuclides likely to be detected in aerosol samples, a series of air-sampling and γ-spectroscopic analysis scenarios were tested. • Radon and radon progeny diurnal fluctuation inside the γ-spectrometry laboratory is monitored and correlated with external meteorological parameters as well as with the germanium detectors' corresponding photopeaks. • For photopeaks always detected in the background the average count-rate obtained from a series of background spectra of the same duration is recommended to be used, while for photopeaks close to the limit of detection the count-rate should be determined from a longer spectrum. • A 2-h delay prior to the gamma spectroscopic analysis of air filter samples significantly improves MDAs, while for air-sampling times of the order of several days, a 24-h delay is recommended to allow for thoron progeny decay and optimize MDAs. [ABSTRACT FROM AUTHOR]

This study presents a method of measuring the activity of a specific radionuclide 234mPa in samples placed in bulk transport containers under changing background conditions. The method makes it possible to measure specific activity of 234 mPa in objects without the need for sampling. The change in the effective sample volume limited by the surfaces of the containers is considered depending on the density of the measured material and the energy of gamma radiation of the radionuclide. The high sensitivity of scintillation detector, supplemented by adequate Monte Carlo simulation, allows spectrum measurements to be taken in a short time (less than an hour) with subsequent determination of specific activity. A comparison of measurement results and calculation of 234mPa activity in samples with different densities and compositions using the proposed algorithm, and those obtained by an HPGe spectrometer, demonstrated the high efficiency of the proposed solution. • Big amount of sample and scintillation crystals for 238U estimation reduces significantly the measurement time. • Reducing the spectrum measurement time reduces the influence of the external radiation background on the measurement results. • To determine the metrological parameters of the equipment is necessary to determine the effective sample volume. • Monte Carlo simulation in the spectrum processing allows to measure the activity of 234mPa at the level of 20 Bq/kg. [ABSTRACT FROM AUTHOR]

The minimum detectable activity (MDA) for gamma spectrometric measurements was studied as a function of filling height for two detectors having different background characteristics and for two sample matrices: a water sample with a low content of natural radionuclides, and zircon sand, with high activities of uranium and thorium. The zircon sand is also a material in which the self-attenuation of low-energy gamma photons will be high. The results show that for the water sample it is always favourable to completely fill the sample container. However, due to the inherent content of naturally occurring radionuclides in the zircon sand the MDA may not necessarily improve with the filling height, since an increased amount of sample will increase the background in the spectrum as well. [ABSTRACT FROM AUTHOR]

A new dipping method was studied for the measurement of radioactive solution using plastic scintillator sheets and pellets (PSs) and a liquid scintillation counter. The method consists of analyzing the PSs dipped into test solution composed of nine compounds with five different radionuclides, and measuring them by using the 'in solution' and 'without solution' method. A qualitative analysis based on the obtained spectra and a quantitative analysis by using the empirical linear relationships between radioactivity and count rate were possible. Minimum detectable activities of this method were calculated and compared with World Health Organization guidelines for drinking water. [ABSTRACT FROM AUTHOR]

Tracking scapular motion can be challenging. More research is needed to determine the best practices for scapular measurement in multi-planar tasks. The purpose of this study was to compare the repeatability of scapular kinematics during a functional task protocol calculated from different calibration procedures. It was hypothesized that select poses would improve repeatability in specific tasks. The torso, humerus, and scapula were tracked with optical motion capture in two sessions for ten pain-free participants. Scapular calibrations were completed in five poses: neutral, maximum elevation, 90° abduction, hand to contralateral shoulder, and hand to back. Each participant completed eight functional tasks (Comb Hair, Wash Axilla, Tie Apron, Overhead Reach, Side Reach, Forward Transfer, Floor Lift, Overhead Lift). Scapular angles were calculated with five different calibration procedures and extracted at 30° increments of humeral elevation in each task. Mean difference, limits of agreement, intraclass correlations, and minimal detectable change (MDC) were calculated for each task and elevation level. The inclusion of different calibration poses did not markedly improve outcomes over the maximum elevation double calibration for most tasks. Using this calibration procedure, median MDCs were 10.0° for upward rotation, 13.7° for internal rotation, and 9.8° for tilt. [ABSTRACT FROM AUTHOR]

In order to meet the needs of rapid classification and measurement of the radioactive waste, a clearance level radioactive waste measurement system has been successfully developed and applied, achieving the goal of waste minimization. The measurement system consisted of 34 NaI(Tl) detectors taking into account the detector layout, detection efficiency and shielding chamber (to reduce the background of the environment). The NaI(Tl) detector array was built by a geometric condition of spatially symmetric to measure gamma rays. The shielding chamber composed of 2 mm copper and 10 mm lead is used as an passive shielding, and the radioactive waste is placed inside the shielding chamber, which suppress the gamma rays from the decay of 40K, 208Tl and other nuclides in the environment. A method to determine the counting of energy interval for the gamma rays is proposed to obtain the radioactivity of the radioactive waste package. The performance testing results of the measurement system show that the energy resolution and efficiency for 661.7 keV (137Cs) are 7.84% and 69.49% respectively, and the minimum detectable activity of 137Cs is 24.52 Bq. All these indicate that the indices of the clearance level radioactive waste measurement system have reached the international recommended level. [ABSTRACT FROM AUTHOR]

Gamma spectrometry for environmental samples of low specific activities demands low minimum detection levels of measurement. An attempt has been made to lower the gamma detection level of measurement by optimizing the sample geometry, without compromising on the sample size. Gamma energy of 50–200 keV range was chosen for the study, since low energy gamma photons suffer the most self-attenuation within matrix. The simulation study was carried out using MCNP based software “EffCalcMC” for silica matrix and cylindrical geometries. A volume of 250 ml sample geometry of 9 cm diameter is optimized as the best suitable geometry for use, against the in-practice 7 cm diameter geometry of same volume. An increase in efficiency of 10%–23% was observed for the 50–200 keV gamma energy range and a corresponding lower minimum detectable activity of 9%–20% could be achieved for the same.

We conceptually develop a scintillation-based sensing module for marine gamma-radiation monitoring deployed in an autonomous underwater glider to provide rapid responses to radiological emergencies. First, we replace the forward section of the glider with a robust YAlO3:Ce scintillator, and we analyze several streamlined scintillator configurations with different geometries via simulations of the mechanical and sensing performances. We calculate the minimum thickness required for the scintillator to remain operationally stable in deep ocean water for hemispherical and conical scintillator shapes. Next, we study the advantages and disadvantages of each shape in terms of the drag force and detection efficiency. After the background-radiation estimation of seawater, we calculate the minimum detectable activity (MDA) according to the counting time, which is a key factor in system operation. We find that all configurations can detect 137Cs within 30 min even at distances >600 km from a high-level-nuclear-accident site. Even in relatively minor instances, dozens of hours are sufficient for the optimized sensing module to satisfy a given MDA goal for 137Cs. Our results indicate that radioactivity data can be effectively mapped in 3D by autonomous motion of a monitoring system with the proposed sensing module. [ABSTRACT FROM AUTHOR]

In this study, we qualitatively and quantitatively analyzed unmanned aerial vehicle (UAV)-based radiation sensor systems suitable for specific survey missions. We examined a variety of UAVs, radiation sensors, and radiological survey missions; after reviewing previous studies that developed and conducted field tests, we categorized them by mission and suggested suitable types of UAVs and radiation sensors for each mission. To quantitatively analyze various system designs previously suggested, we proposed a new figure of merit (FOM) formula that can explain the mutual effects of parameters of both radiation sensors and UAVs on system performance. After targeting a radiological survey mission, we selected UAV and radiation sensor types qualitatively. Then, the quantitative FOM formula can be employed to efficiently assess whether the system achieves the required minimum detectable activity (MDA) without field test, while keeping the error of the MDA values in the order of 100. After defining the constraints including the proposed FOM formula, we replicated a severe nuclear power plant accident scenario. We found that one fixed-wing UAV and multiple rotary-wing UAVs are the minimum number of UAVs, and thus the optimal system for timely achievement of a satisfactory MDA and estimation of the three-dimensional radiation distribution contributed by both ground radiation and an atmospheric radioactive plume. • A new FOM formula is developed to analyze UAV-based radiation sensor system designs. • MDA values of system designs in earlier research are correlated and compared. • Optimized sensor systems are determined using a case study. • In the case study, radiation deposited on the ground and in a plume are monitored. [ABSTRACT FROM AUTHOR]

Abstract Lead-210 in drinking water can be rapidly determined by liquid scintillation counting (LSC) using a new sulfate precipitation method. In this method, 210Pb was first preconcentrated from water using iron hydroxide co-precipitation followed by sulfate precipitation to decontaminate most of non-alkaline earth elements. The Pb in the sulfate precipitate was then dissolved in strong alkaline solution, while alkaline earth elements (Sr, Ba, Ra) were separated as the sulfate/carbonate precipitate. To optimize the method, the influences of different acids and sulfate concentration on sulfate precipitation as well as the effects of pH, the added SO 4 2−/CO 3 2− concentrations and the Sr/Ba contents in the sulfate precipitate on the dissolution of PbSO 4 were studied. In addition, X-ray fluorescence (XRF) analysis was applied for rapid determination of the chemical recovery and triple-to-double coincidence ratio (TDCR) quench correction curve for counting of 210Pb by LSC was established. The method was validated using 5 L of tap water samples and minimum detectable activity concentration (MDC) of ∼0.016 Bq·L−1 was achieved, which is sufficiently sensitive to meet the guidance level of 0.1 Bq·L−1 for 210Pb in drinking water as recommended by the World Health Organization (WHO). Highlights • A rapid method for direct analysis of 210Pb in drinking water was developed. • X-ray fluorescence analysis was proved to be suitable for determining the chemical recovery of lead. • The TDCR quench correction curve was established for the counting efficiency of 210Pb by LSC. [ABSTRACT FROM AUTHOR]

Tensiomyography (TMG) has gained popularity as a tool to quantify muscle contractile properties. However, it is unclear whether joint angle and inter-stimulus interval influence the test-retest reliability of TMG. Fifteen participants (13M/2F; 29.5 ± 7.4 y) underwent TMG recording of the biceps brachii (BB) at 10°, 45° and 90° of elbow flexion with 10 and 20 s inter-stimulus rest intervals in a randomised order on two separate days. The intra-class correlation coefficient (ICC2,1) and 95% confidence interval (95%CI) were calculated for delay time (Td), contraction time (Tc), sustain time (Ts), relaxation time (Tr) and maximal displacement (Dm). Additionally, the standard error of measurement (SEM), coefficient of variation (CV) and minimal detectable change (MDC) were obtained. Across conditions the ICC2,1 varied for each parameter (Td:0.465-0.947, Tc:0.452-0.831, Ts:0.717-0.918, Tr:0.841-0.935, Dm:0.646-0.900). CV was low for Td (2.1-3.0%), Tc (4.4-7.7%) and Ts (5.5-6.9%) but greater for Tr (10.0-15.3%) and Dm (5.8-13.1%) across conditions. Ts (∼210 ms, P < 0.001) and Dm (∼17 mm, P < 0.001) were greatest at 10° and 90°, respectively, while Td was shortest (∼22.9 ms, P = 0.002) at 10° compared to other angles. No differences were observed between inter-stimulus intervals or day. The findings are expected to help shape best practice methods for TMG use in field and research based settings. [ABSTRACT FROM AUTHOR]

Background: The Lower Quarter Y Balance Test (YBT-LQ) has been widely used in the field to assess dynamic balance performance in various populations. However, no study has demonstrated test-retest reliability of the YBT-LQ in adolescents including several age cohorts, even though reliability is necessary to provide repeatable performance data.Objective: Thus, we examined test-retest reliability of the YBT-LQ in healthy adolescents.Methods: In a school setting, 178 secondary school students (93 female, 85 male) in sixth to eleventh grades (11-19 years) performed the YBT-LQ twice, 7 days apart. Normalized maximal reach distances (% leg length) for all three directions (i.e., anterior, posterolateral, posteromedial) and both legs and the composite score were used as outcome measures. Intraclass correlation coefficient (ICC3,1) and standard error of measurement (SEM) were calculated to assess relative and absolute test-retest reliability, respectively. Practical relevance of the YBT-LQ was determined by calculating the minimal detectable change (MDC95%).Results: Irrespective of grade, test-retest reliability for all distances reached was predominately "excellent" (i.e., ICC3,1 > 0.75) and the rather small SEM values ranged from 1.77 to 5.81%. Depending on grade and reach direction, MDC values of 4.90 to 16.10% represent the minimum amount of change needed to identify clinically relevant effects in repeated measurements of the YBT-LQ performance.Conclusions: The observed values suggest that the YBT-LQ is a reliable test and suitable to detect changes of dynamic balance performance in healthy adolescents from grade six to eleven (i.e., aged 11-19 years). [ABSTRACT FROM AUTHOR]

In this contribution, we present and analyze datasnooping in the context of the DIA method. As the DIA method for the detection, identification and adaptation of mismodelling errors is concerned with estimation and testing, it is the combination of both that needs to be considered. This combination is rigorously captured by the DIA estimator. We discuss and analyze the DIA-datasnooping decision probabilities and the construction of the corresponding partitioning of misclosure space. We also investigate the circumstances under which two or more hypotheses are nonseparable in the identification step. By means of a theorem on the equivalence between the nonseparability of hypotheses and the inestimability of parameters, we demonstrate that one can forget about adapting the parameter vector for hypotheses that are nonseparable. However, as this concerns the complete vector and not necessarily functions of it, we also show that parameter functions may exist for which adaptation is still possible. It is shown how this adaptation looks like and how it changes the structure of the DIA estimator. To demonstrate the performance of the various elements of DIA-datasnooping, we apply the theory to some selected examples. We analyze how geometry changes in the measurement setup affect the testing procedure, by studying their partitioning of misclosure space, the decision probabilities and the minimal detectable and identifiable biases. The difference between these two minimal biases is highlighted by showing the difference between their corresponding contributing factors. We also show that if two alternative hypotheses, say Hi and Hj, are nonseparable, the testing procedure may have different levels of sensitivity to Hi-biases compared to the same Hj-biases. [ABSTRACT FROM AUTHOR]

Abstract An autonomous sensor for the in-situ radioactivity measurement is developed，based on NaI(Tl) crystal, to detect the activity concentrations of natural and anthropogenic radionuclides in seawater. Its electronics module, integral enclosure and spectrum analysis were presented. The energy, resolution and efficiency were calibrated. Monte Carlo simulation and the minimum detection estimations were realized. The sensor was tested in the water tank and then successfully deployed for the continuous monitoring in the marine environment in Qingdao offshore for the performance test, background measurement and environmental survey. Some results were deduced from the gamma ray spectra and discussed in comparison with those from the laboratory and literatures. Highlights • An autonomous sensor for marine radioactive monitoring is given. • Calibration of energy, resolution and efficiency are analyzed. • Monte Carlo simulation and new electronic design are presented. • Field measurements in Qingdao offshore are discussed. • Minimum detectable activity is compared with similar systems. [ABSTRACT FROM AUTHOR]

Objective The d2 Test of Attention (D2) is a commonly used measure of selective attention for patients with schizophrenia. However, its test–retest reliability and minimal detectable change (MDC) are unknown in patients with schizophrenia, limiting its utility in both clinical and research settings. The aim of the present study was to examine the test–retest reliability and MDC of the D2 in patients with schizophrenia. Method A rater administered the D2 on 108 patients with schizophrenia twice at a 1-month interval. Test–retest reliability was determined through the calculation of the intra-class correlation coefficient (ICC). We also carried out Bland–Altman analysis, which included a scatter plot of the differences between test and retest against their mean. Systematic biases were evaluated by use of a paired t -test. Results The ICCs for the D2 ranged from 0.78 to 0.94. The MDCs (MDC%) of the seven subscores were 102.3 (29.7), 19.4 (85.0), 7.2 (94.6), 21.0 (69.0), 104.0 (33.1), 105.0 (35.8), and 7.8 (47.8), which represented limited-to-acceptable random measurement error. Trends in the Bland–Altman plots of the omissions (E1), commissions (E2), and errors (E) were noted, presenting that the data had heteroscedasticity. Conclusions According to the results, the D2 had good test–retest reliability, especially in the scores of TN, TN-E, and CP. For the further research, finding a way to improve the administration procedure to reduce random measurement error would be important for the E1, E2, E, and FR subscores. [ABSTRACT FROM AUTHOR]

Background: Increasing stiffness in the upper trapezius muscle may contribute to imbalance of scapular motion, and result in shoulder and neck discomfort during shoulder flexion. Therefore, it is essential to quantify upper trapezius stiffness in various shoulder positions in order to aid in the prevention of these disorders and to optimize rehabilitation.Objectives: The objectives of the present study were to examine the intra and inter-tester reliability of MyotonPRO device in measuring upper trapezius stiffness and its ability to determine changes in stiffness during shoulder flexion.Methods: Twenty healthy male subjects (mean age: 28.3±4.8 years) were studied. The stiffness of upper trapezius was quantified using the MyotonPRO device.Results: The results revealed excellent intra and inter-tester reliability for measuring upper trapezius stiffness with the shoulder in a neutral position, and also found a 14.2% increase in stiffness upon shoulder flexion between 0° and 60° of flexion. Minimal detectable change (MDC) was 26.3 N/m.Conclusions: Our findings indicate that MyotonPRO device is a feasible tool to quantify upper trapezius stiffness as well as changes in muscle stiffness. Thus, it is important to assess the changes in upper trapezius muscle stiffness due to pathology or treatments for future studies. [ABSTRACT FROM AUTHOR]

Abstract An automated low-background NaI(Tl) gamma-ray spectrometer for in situ underwater measurements consisting of a submersible unit with a radiation detector and of a surface microcomputer unit is developed and described. Along with an ultra low-background NaI(Tl) radiation sensor, the submersible unit contains a specially designed FPGA-based electronics with low energy consumption and with abilities both for remote data acquisition by a 1200 m conducting cable and for an autonomous operation mode. The unit is enclosed in a waterproof polyacetal housing withstanding a pressure of 4 MPa at a depth of 400 meters. The surface microcomputer unit contains an all-in-box software for acquisition, storage, and processing of data from the detector unit, for real-time monitoring of activities of dissolved radionuclides, for their identification and quantification. The software functions are accessed remotely by a web-interface using Wi-Fi or Ethernet. Several techniques for gain control (including an auto-adjustment of the gain by setting a selected photopeak in a prescribed channel) together with the corresponding approaches to the energy-scale calibration are implemented and examined over a wide temperature range − 10 ÷ + 50 ° C in a thermo-chamber calibration experiment with 152Eu point gamma-ray sources. Calibrating the energy resolution of the detector is performed from line-width measurements of reference gamma-ray sources. The detection-efficiency calibration is carried out using Monte Carlo simulations based on the GEANT4 code taking into account the materials and geometry of the detector as well as the water environment. In addition, the efficiency of the detector immersed in a 8 m 3 water tank with dissolved gamma-ray sources of 139Ce, 137Cs and 40K of known activities is determined experimentally and compared with the theoretical findings. Finally, a trial deployment of the gamma-spectrometer in the Yellow Sea together with test measurements of the activity concentrations of dissolved radionuclides is fulfilled. The Minimum Detectable Activity concentrations (MDA) for 137Cs in fresh and sea water are calculated from the water tank experiment and from the test deployment experiment correspondingly. [ABSTRACT FROM AUTHOR]

Objective: Although arthroscopic Bankart repair is widely performed, little is known concerning the healing process of the Bankart lesion. This study aimed to describe the sonographic sequential change of the anteroinferior labrum following arthroscopic Bankart repair, both quantitatively and qualitatively.Materials and Methods: Twenty-five subjects who had undergone arthroscopic Bankart repair were investigated using a sonographic diagnostic device equipped with shear-wave elastographic technology. In addition to measuring the elasticity of the anteroinferior labrum, the B-mode echogram of the anteroinferior labrum was classified into three grades based on the relative echogenicity. Assessment was performed in the affected shoulder 1, 2, 3, 4, 5, 6, and 12 months postoperatively and in the contralateral shoulder 1 month postoperatively for the control.Results: The mean elasticity of the anteroinferior labrum in the affected shoulder 1 and 2 months postoperatively was significantly lower than in the contralateral shoulder (p < 0.001 for both). However, no significant difference was found after 3 months postoperatively. B-mode echograms of the anteroinferior labrum in the contralateral shoulder were classified as grade 0 in all subjects (100%), whereas the percentage of grade 0s in the affected shoulder was 0, 4, 96, and 100% at 1, 2, 3, and 4 months postoperatively.Conclusion: Both quantitative and qualitative assessment of repaired anteroinferior labrum using ultrasound became comparable with the contralateral shoulder 3-4 months postoperatively. Ultrasound is a useful decision-supporting tool to prescribe postoperative rehabilitation protocol following arthroscopic Bankart repair, although functional recovery should also be evaluated on an individual basis. [ABSTRACT FROM AUTHOR]

In situ radiation measurements are commonly used to detect radioactive material in luggage; at border control checkpoints; for in-field monitoring; during the illicit transfer of nuclear material; and at radioactive contamination sites, e.g., the Fukushima nuclear accident site. In considering the high brightness, fast decay time, and good energy resolution of cerium-doped lanthanum bromide [LaBr3(Ce)] scintillation detectors, this work conducted an experimental analysis aimed at evaluating the potential for applying LaBr3(Ce) detectors to in situ artificial radiation measurements. The effect of the intrinsic radiation of the LaBr3(Ce) detector was investigated. In addition, the intrinsic radiation contribution to the background radiation of the region of interest (ROI) under full-energy peaks for several artificial point sources and the minimum detectable activity (MDA) values of a 3 × 3-in. LaBr3(Ce) detector for several artificial radioactive point sources under unshielded (in the natural background) and well-shielded (in a low background chamber) conditions were calculated. The results indicate that the intrinsic radiation has a significant effect on the background radiation of the ROI especially when the full-energy peaks of several artificial point sources are located in the low-energy region or near 789 and 1400 keV. In addition, the MDAs (the measured time is 300 s) of the LaBr3(Ce) detector for 152Eu (121.78 keV), 133Ba (356 keV), 137Cs (661.7 keV), and 60Co (1332.5 keV) were 218.2, 63.6, 61.3, and 59.6 Bq, respectively, under unshielded conditions and 111.4, 39.1, 46.1, and 38.6 Bq, respectively, under well-shielded conditions. The intrinsic radiation also has some effects on the MDA of the LaBr3(Ce) detector, especially in the low-energy region. Thus, the drawback of its intrinsic radiation limits its application to in situ weak artificial radiation measurements, but LaBr3(Ce) detectors have the potential for use in medium- and high-radiation measurements due to the better energy resolution of these detectors than NaI(Tl) detectors. [ABSTRACT FROM AUTHOR]

Abstract Because of the low detection probability and recognition efficiency of the single-band signal of an infrared point target, the multi-band composite detection probability is analyzed and a multi-band recognition method is proposed. By using the binary hypothesis method, we can conveniently deduce the multi-band theoretical detection threshold and obtain the composite detection probability and false alarm probability. The numerical simulation results show that multi-band composite detection ability is superior to that of single-band. For the difficult classification between background and target spectral signals with serious interference noise in reality, this paper proposes a highly effective spectral signal recognition method based on the optimized AdaBoost algorithm. By virtue of the high classification accuracy of the AdaBoost algorithm, with the Pruning classifier as a basic classifier to be learnt, the proposed method abandons any abnormal data that seriously deviate from the mean value center of the correction classification data, the end result of which reduces the number of iterations and enhances the classification effect of the AdaBoost algorithm. Compared with other algorithms from test results, the optimized AdaBoost algorithm has higher recognition accuracy and quicker computation, and it reduces the sensitivity to noise to prevent the phenomenon of over-fitting. [ABSTRACT FROM AUTHOR]

Highlights • An equivalent model of infrared emission is presented for optical window. • The model improves stray radiation analysis efficiency for complex optical system. • Infrared stray radiation flux and direction are recorded to design control scheme. Abstract Stray radiation analysis is a special radiation transport problem characterizing the directional propagation and small probability simulation. The computational cost increases significantly when lens or optical windows exist in the optical system, due to the simulation requirement for ray transmission in the semi-transparent medium. For the high-temperature optical window outside of the hypersonic vehicle etc., the infrared radiation from window becomes the main stray radiation and reduces the detection or image quality adversely. To fulfil the infrared stray radiation analysis for such optical system and improve the efficiency, an equivalent model of infrared emission for the optical window is presented. According to the simulation of ray generation and propagation in the optical window, the equivalent model is built combining the distributions of launch point and direction for the infrared stray radiation. Then, a simplified infrared optical detection system is taken to verify the presented equivalent model. The infrared stray radiation flux and direction distribution are recorded on the entrance pupil plane of the optical system using Monte Carlo method. The results show that the infrared stray radiation analysis method, employing the equivalent model of infrared emission, is reliable and more effective. [ABSTRACT FROM AUTHOR]

The international monitoring system (IMS) has been developed to verify compliance with the comprehensive nuclear test-ban treaty (CTBT) and radionuclide monitoring stations are the smoking gun for underground nuclear explosions identification. One of the main objectives of the verification regime is to improve the sensitivity of measurements providing background reduction and, as a result, decrease the minimum detectable activity (MDA) values. At this ENEA laboratory an anticoincidence system has been developed: the system is comprised of a high purity germanium (HPGe) detector surrounded by a low-background shield and two plastic scintillators able to detect coincident cosmic-ray interactions. Tests conducted with the anticoincidence system have shown a reduction of the Compton continuum that contributes to the spectrum background and the measured MDA values, compared to those obtained using the standard system, decreased for all the four radioxenon isotopes. [ABSTRACT FROM AUTHOR]

Purpose. The study aimed to determine the within- and between-session reliabilities as well as the minimal detectable change (MDC) of generally used temporal, kinematic, and kinetic parameters during the sit-to-stand (STS) task in typical children. Methods. The study involved 10 typical children (9.8 ± 1.6 years old). Motion analysis and force plate systems were used to collect markers for 3-dimensional trajectories in space and measure the ground reaction force. The total of 29 reflective markers were placed on each participant's body in accordance with the Helen Hays marker set model by 1 rater on 2 separate days within the span of 1 week. Each subject was asked to perform an STS task 3 times from a height-adjustable chair. Intraclass correlation coefficient (ICC), standard error of measurement (SEM), and MDC for temporal, kinematic, and kinetic parameters were calculated within and between sessions. Results. The results indicated that the temporal parameters achieved excellent (ICC > 0.75), the kinematic parameters presented poor to excellent (0.232 < ICC < 0.997), and the kinetic parameters showed fair to excellent (0.635 < ICC < 0.977) reliabilities in both within- and between-session analyses. The SEM of most kinematic parameters was less than 2° both within and between sessions. In addition, the MDC values for between sessions ranged 1.25-12.64°. Conclusions. The findings support the reliability of using 3-dimensional motion analysis and force plate systems for measuring temporal, kinematic, and kinetic parameters for STS tasks in typical children. [ABSTRACT FROM AUTHOR]

Background 3D freehand ultrasound enables the creation of volumetric data. The acquisition of morphological features, such as muscle volume, is influenced by the variations in force applied to the skin with the ultrasound probe. To minimise the deformations, a concave-shaped plastic mount combined with a custom-shaped gel pad was developed for the ultrasound head, named Portico. This study analyses to what extent the Portico reduces muscle deformation and corresponding errors in estimating muscle volume. Method Twenty medial gastrocnemius (MG) muscles were assessed (10 from typically developing children; 10 from children with spastic cerebral palsy). Two repetitions were acquired in each of the following approaches: (1) with the lower leg submerged in a water tank as a non-deformed reference; (2) probe-on-skin (PoS) as the conventional approach and (3) the newly introduced Portico. PoS and Portico data were registered with respect to the ones corresponding in a water tank. An in-house software package (Py3DFreeHandUS) was used to process the data and MG volume was estimated using MeVisLab. The minimal detectable change (MDC) was calculated. Results With respect to the PoS approach, the Portico reduced muscle deformation by 46%. For both the typically developing and spastic cerebral palsy cohorts, lower MDCs were found when using the Portico. Discussion Despite the improvements, the Portico did not yield statistically more reliable MG volume estimations than the traditional PoS approach. Further improvement can be attained by optimising the fit between the gel pad and the curvature of the limb, using a larger choice of Portico geometries. [ABSTRACT FROM AUTHOR]

Radioactive xenon (mainly 131m Xe, 133 Xe, 133m Xe and 135 Xe) are tracked as markers of nuclear weapons testing. The CEA has developed the PIPSBox, a measurement cell able to detect electrons emitted by xenon nuclides. Combined with an ultra-low background γ spectrometer, electron detection capacities allow reaching minimum detectable activities (MDA) for a 3-day long measurement of about 0.5 mBq for the four xenon radionuclides. Compared to a classical measurement cell, MDAs are improved by a factor of 2–4. [ABSTRACT FROM AUTHOR]

This study investigated the natural radioactivity in flour consumed in Kuwait. To cover a wide range of samples, wheat, rice and gram (chickpeas) based flour samples were tested. Gamma spectrometry revealed the presence of 226Ra, and 40K in all samples, while 228Ra was detected in 14 out of the 18 samples. The activity concentrations of the three radionuclides were found to be within normal levels, and hence so did the estimated annual effective doses. Moreover, the estimated lifetime cancer risk was found to be well below the acceptable level. Hence, these findings confirm the radiological safety of flour consumed in Kuwait for the three targeted radionuclides. Interestingly, significant statistical differences were found in the averages of the activity concentrations that were sensitive to the ingredient of the flour. [ABSTRACT FROM AUTHOR]

The design of a radioxenon detection system utilizing a CdZeTe crystal and a plastic scintillator coupled to an array of SiPMs to conduct beta-gamma coincidence detection for atmospheric radioxenon monitoring, as well as the measurement of 135 Xe and 133∕133m Xe, have been detailed previously. This paper presents recent measurements of 133∕133m Xe and 131m Xe and the observation of conversion electrons in their coincidence spectra, as well as a 48-hour background measurement to calculate the Minimum Detectable Concentration (MDC) of radioxenon isotopes in the system. The identification of Regions of Interest (ROIs) in the coincidence spectra yielded from the radioxenon measurements, and the subsequent calculation of the MDCs of the system for 135 Xe, 133∕133m Xe, and 131m Xe, are also discussed. Calculated MDCs show that the detection system preforms respectably when compared to other state of the art radioxenon detection systems and achieved an MDC of less than 1 mBq/m 3 for 131m Xe, 133 Xe, and 133m Xe, in accordance with limits set by the Comprehensive Nuclear-Test-Ban Treaty (CTBTO). The system also provides the advantage of room temperature operation, compactness, low noise operation and having simple readout electronics. [ABSTRACT FROM AUTHOR]

Plutonium dioxide (PuO2) is used to fabricate a mixed oxide fuel for fast breeder reactors. When a glove box containing PuO2 fails, such as by rupture of a glove or a vinyl bag, airborne contamination of plutonium (Pu) can occur. If a worker inhales PuO2 particles, they will be continually irradiating their lung tissue with alpha particles, and this could cause lung cancer. The nasal smear and nose blow methods are useful for checking workers for PuO2 intake in the field. However, neither method can evaluate the quantitative activity of Pu. No alpha-particle detector that can be used for direct measurements in the nasal cavity has been developed. For direct and quantitative measurement, it is required that a shape of the detector should be a fine bar which inserts itself in the nose to measure the accurate activity of Pu. Therefore, we developed a nasal monitor capable of directly measuring the activity of Pu in the nasal cavity to estimate the internal exposure dose of a worker. Prismatic-shaped 2 × 2 acrylic light guides were used to compose a detector block, and a ZnS(Ag) scintillator was adhered to the surface of these light guides. Silicon photomultiplier (SiPM) arrays with 8 × 8 channels were used as a photodetector. Actual PuO2 particles were measured using the nasal monitor. The nasal monitor could be directly inserted in the nasal cavities, and the activity distribution of Pu was obtained by the nasal monitor. The average efficiencies in 4-pi were 11.4 and 11.6% for the left and right nasal cavities, respectively. The influence of gamma and beta rays from Cesium-137 (137Cs) Strontium-90 (90Sr) on the detection of the alpha particles of Pu was negligible. The difference in the measured Pu activity between the ZnS(Ag) scintillation counter and the nasal monitor was within 4.0%. Therefore, it was considered that the developed nasal monitor could be used in direct Pu determination to estimate the internal exposure dose of workers. [ABSTRACT FROM AUTHOR]