Calibration Monitoring Research Articles

Characterisation of the UK high energy proton research beamline for high and ultra-high dose rate (FLASH) irradiation

Objective. This work sets out the capabilities of the high energy proton research beamline developed in the Christie proton therapy centre for Ultra-High Dose Rate (UHDR) irradiation and FLASH experiments. It also characterises the lower limits of UHDR operation for this Pencil Beam Scanning (PBS) proton hardware. Approach. Energy dependent nozzle transmission was measured using a Faraday Cup beam collector. Spot size was measured at the reference plane using a 2D scintillation detector. Integrated depth doses (IDDs) were measured. EBT3 Gafchromic film was used to compare UHDR and conventional dose rate spots. Our beam monitor calibration methodolgy for UHDR is described. A microDiamond detector was used to determine dose rates at zref. Instantaneous depth dose rates were calculated for 70–245 MeV. PBS dose rate distributions were calculated using Folkerts and Van der Water definitions. Main results. Transmission of 7.05 ± 0.1% is achieveable corresponding to a peak instantaneous dose rate of 112.7 Gy s−1. Beam parameters are comparable in conventional and UHDR mode with a spot size of σ x = 4.6 mm, σ y = 6.6 mm. Dead time in the beam monitoring electonics warrants a beam current dependent MU correction in the present configuration. Fast beam scanning of 26.4 m s−1 (X) and 12.1 m s−1 (Y) allows PBS dose rates of the order tens of Grays per second. Significance. UHDR delivery is possible for small field sizes and high energies enabling research into the FLASH effect with PBS protons at our facility. To our knowledge this is also the first thorough characterisation of UHDR irradiation using the hardware of this clinical accelerator at energies less than 250 MeV. The data set out in this publication can be used for designing experiments at this UK research facility and inform the possible future clinical translation of UHDR PBS proton therapy.

ECG and NIBP Simulators in One Device Display on TFT Nextion

Accurate monitoring of NIBP (Non-Invasive Blood Pressure) parameters using vital sign monitors is crucial for patient care. Therefore, calibration of vital sign monitors is essential to ensure their safety and reliability. The purpose of this study is a vital sign simulator was developed, integrating ECG and NIBP parameters with a TFT Nextion display, to calibrate ECG and NIBP readings on vital sign monitors. The system utilized the Arduino Mega 2560 as the central controller and the MPX5050GP sensor for NIBP measurement and motor pump control. The NIBP parameters were measured at two settings: 60/30 and 80/50. The results showed a maximum systolic error of 3.5% and a diastolic error of 5.6% for the NIBP setting of 80/50. The largest standard deviation value of 2.05 was observed at the NIBP setting of 60/30. The highest uncertainty value of 0.5 was also found in the NIBP 60/30 setting. The obtained data indicated stable module readings within the acceptable threshold for vital sign monitor calibration. The developed vital sign simulator offers a reliable means of calibrating NIBP parameters, enabling accurate blood pressure measurements. Further research and refinement can be conducted to enhance the system's precision and expand its capabilities for calibration of additional vital sign parameters. By ensuring accurate calibration, healthcare professionals can rely on vital sign monitors for effective patient monitoring and diagnosis.

Innovative technologies in the management of diabetes mellitus: prevention of hypoglycemia

One of the strategies for preventing hypoglycemia, along with structured patient education and the use of modern hypoglycemic agents, is self-control of glycemia with the achievement of individual therapeutic goals. Frequently recurring hypoglycemic episodes are associated with impaired recognition of hypoglycemia and increase the risk of severe hypoglycemia up to six times. Prevention of the development of severe hypoglycemia may be of key importance for the prevention of adverse cardiovascular events and the risk of sudden death in patients with diabetes mellitus. Repeated hypoglycemic episodes can lead to impaired recognition of hypoglycemia, as a result of which a lower blood glucose level is necessary for the development of clinical symptoms of hypoglycemia. The use of individual glucose meters is currently relevant, despite the active introduction into clinical practice of continuous monitoring of glycemia and flash monitoring. ccording to the Russian “Algorithms of specialized medical care for patients with diabetes mellitus”, patients are recommended to conduct self-monitoring using individual glucose meters at least 4 times a day when using continuous monitoring of glycemia in real time and at least 2 times a day when using flash monitoring of glycemia to assess accuracy and / or calibration monitoring data and in order to resolve the issue of correction of ongoing therapy. The desire for strict and adequate self-control dictates the need to use the latest means of glycemia control – intelligent glucose meters with high accuracy, ease of use and reliability of blood glucose measurements. The introduction of intelligent technologies – “smart” glucose meters using a mobile application, with the functions of “no coding”, “second chance”, data transmission to the attending physician – makes it possible to carry out remote monitoring, providing more effective management of diabetes mellitus.

Monitoring of multivariate calibration models in the absence of new reference values: The regression case

Multivariate calibration models are one of the most predominant tools in analytical chemistry for the non-destructive quantification of constituents. While pipelines, methods, and software are widely available for training calibration models, the monitoring strategies to track the prediction performance in time are still limited and are one of the emerging research topics in chemometrics and machine learning. Moreover, for the sake of efficiency, the development of modern monitoring strategies requires tools that do not require new reference values at each time point. The current study addresses the problem of monitoring calibration models for regression. We present a monitoring paradigm and propose two methods to monitor the performance of the model. The two methods focus on bias drift and spectral variation drift. We present the derivation of the methods and their application to two real case studies from the agrofood industry involving milk composition and apple harvesting. Conclusions and recommendations are presented for practitioners, as well as views for future work in this domain of research.

ВІДПОВІДНІСТЬ ВІДТВОРЕННЯ КОЛЬОРУ НА МОНІТОРІ ПРИ ПРОЕКТУВАННІ АРХІТЕКТУРНИХ ТА ДИЗАЙНЕРСЬКИХ ОБ’ЄКТІВ

The paper substantiates the importance of appropriate color reproduction when designing architectural and designer objects in computer systems. Most studies of color in architecture and design are related to its characteristics, lighting conditions, the influence of the source, environment, visual perception, etc., rather than the accuracy of its reproduction. The color selected by the designer and the customer from the standard palettes may be distorted when displayed on a monitor in the software. Color deviations from the palette samples can be significant and visually noticeable on the monitor, which is undesirable. The article compares two monitors in terms of color reproduction quality. For this purpose, was described software and tool methods for configuring monitors. The monitors were calibrated and profiled using an instrumental method using a spectrophotometer. The obtained profiles were analyzed in comparison with sRGB and the color differences of the test scale fields were analyzed by color difference ∆E 2000. The suitability of each monitor for project visualization was determined based on monitor calibration and profiling results. The authors compared the coverage of sRGB, Adobe RGB, and ProPhoto RGB and gave practical recommendations for choosing a working profile when working and controlling color by monitor. The algorithms for calculating and using unreproducible colors were analyzed when switching from a larger color gamut to a smaller one. The article also includes practical recommendations for preparing the monitor for working with color. Therefore, it is possible to improve the color reproduction accuracy and get the color close to standard palettes on the monitor by calibrating and profiling it. The process of setting up a monitor is especially relevant in the case of preparing projects in digital form with their visualization in software.

Evaluation of Temporal Stability in Radiometric Calibration Network Sites Using Multi-Source Satellite Data and Continuous In Situ Measurements

The radiometric calibration network (RadCalNet) comprises four pseudo-invariant calibration sites (PICS): Gobabeb, Baotou, Railroad Valley Playa, and La Crau. Due to its site stability characteristics, it is widely used for sensor performance monitoring and radiometric calibration, which require high spatiotemporal stability. However, some studies have found that PICS are not invariable. Previous studies used top-of-atmosphere (TOA) data without verifying site data, which could affect the accuracy of their results. In this study, we analyzed the short- and long-term radiometric trends of RadCalNet sites using bottom-of-atmosphere (BOA) data, and verified the trends revealed by the TOA data from Landsat 7, 8, and Sentinel-2. Besides the commonly used methods (e.g., nonparametric Mann–Kendall and sequential Mann–Kendall tests), a more robust Sen’s slope method was used to estimate the magnitude of the change. We found that (1) the trends based on TOA reflectance contrasted with those based on BOA reflectance in certain cases, e.g., the reflectance trends in the red band of BOA data for La Crau in summer and autumn and Baotou were not significant, while the TOA data showed a significant downward trend; (2) the temporal trends showed statistically significant and abrupt changes in all PICS, e.g., the SWIR2 band of La Crau in winter and spring changed by 1.803% per year, and the SWIR1 band of Railroad Valley Playa changed by >0.282% per year, indicating that the real changes in sensor performance are hard to detect using these sites; (3) spatial homogeneity was verified using the coefficient of variation (CV) and Getis statistic (Gi*) for each PICS (CV < 3% and Gi* > 0). Overall, the RadCalNet remains a highly reliable tool for vicarious calibration; however, the temporal stability should be noted for radiometric performance monitoring of sensors.

Development of an Automated Temperature Calibration Monitoring System Using Internet of Things for the Regional Meteorology, Climatology, and Geophysics Agency (Bmkg) in Medan

The Regional Meteorology, Climatology, and Geophysics Agency (BMKG) plays a crucial role in providing accurate and reliable services related to meteorology, climatology, and geophysics. Temperature observation is one of the important tasks carried out by the BMKG as it is essential for weather and climate forecasting, as well as for predicting natural disasters. To ensure the accuracy of the data, the thermometers used for temperature observation must be in good working condition and calibrated regularly. According to the Republic of Indonesia Law No. 31, Article 48, Year 2009 on Meteorology, Climatology, and Geophysics (MKG), all observation equipment must be in good working condition and calibrated regularly. Calibration is a crucial step in ensuring the accuracy and operational fitness of the observation equipment. The International Organization for Standardization (ISO) / International Electrotechnical Commission (IEC) 17025:2017 also emphasizes the importance of ensuring the quality and accuracy of all measurement instruments. The Calibration Laboratory at the BMKG Regional Office I in Medan is accredited with ISO/IEC 17025:2017 by the National Accreditation Committee (KAN). However, the calibration process can be time-consuming and requires constant monitoring to achieve stable data. During temperature and humidity calibration, the calibration laboratory's environment must be conditioned to maintain the performance of sensitive instruments that are susceptible to environmental changes. This study aims to design an automated temperature calibration monitoring system using the Internet of Things (IoT) to improve the efficiency of the calibration process and achieve maximum calibration results at the BMKG Regional Office I in Medan. The system will enable the calibration personnel to monitor the calibration process remotely and receive real-time data, allowing for more effective analysis and decision-making.

Abstract 1970: Protecting against algorithmic bias of AI-based clinical decision making tools in oncology

Abstract MOTIVATION: AI-based decision-making tools hold the potential to reduce patient suffering and burden. However, healthcare data reflects inequity, and datasets often lack representation of underprivileged groups. Without systems and methods to protect all patients, we risk making dangerous biases automatic and invisible. We can only ensure protection against bias if performance is monitored in production, continuously and with meaningful measures. Notably, a lack of representation and bias in the validation of diverse ancestry in genetics data results in genetic misdiagnoses and potential health disparities. Similarly, monitoring calibration in addition to receiver operating characteristic curve area under curve (ROC-AUC) in subgroups could have prevented bias predictions leading to underestimation of the health needs of sicker patients. Here, we describe methods and results implemented in an AI-based clinical decision-making tool to protect against bias. METHODS: Our model uses proven techniques and metrics to identify and monitor bias and quantify the magnitude of its impact. Our algorithm compares all demographic subgroups to that of a top performer based on overall model performance (measured by both ROC-AUC and Brier score). To determine if the top-performing subgroup is receiving statistically significant preferential treatment, we perform t-tests for each other subgroup against the top performer (p-value > 0.05 indicates that performance is statistically significant) using sample-wise performance metrics (log-loss in this case). We then quantify the magnitude of the difference by computing the ratio of the top-performer to that of the affected subgroup. The bias detection algorithm is continuously run as our model generates risk predictions based on up-to-date patient data. If the algorithm identifies a bias, it immediately notifies data scientists and engineers to begin rapidly restoring balanced model performance for clinical use by investigating algorithms that optimize for overall and balanced performance by subgroup. RESULTS: We trained and validated our machine learning model to predict 30-day emergency department visits using a data set with over 28,000 oncology patients representing diverse cancer types, races, ethnicities, ages, genders, and socio-economic statuses. Our model performance on a held-out validation data set was exceptional overall (AUC 0.8, Brier score 0.07) and across all cancer type and demographic subgroups (AUC 0.74-0.82, Brier score 0.06-0.1). We continuously monitored our live model in production over three months to ensure consistent and fair performance. Our overall and subgroup performance in production never dropped below AUC 0.75 or above Brier score 0.1. CONCLUSIONS: We demonstrate an effective framework for continuously and automatically detecting and combating algorithmic bias in oncology AI decision-making tools. Citation Format: Renee D. George, Benjamin H. Ellis, Chris J. Sidey-Gibbons, Christine Swisher. Protecting against algorithmic bias of AI-based clinical decision making tools in oncology [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1970.

Upper-Arm Photoplethysmographic Sensor with One-Time Calibration for Long-Term Blood Pressure Monitoring.

Wearable cuffless photoplethysmographic blood pressure monitors have garnered widespread attention in recent years; however, the long-term performance values of these devices are questionable. Most cuffless blood pressure monitors require initial baseline calibration and regular recalibrations with a cuffed blood pressure monitor to ensure accurate blood pressure estimation, and their estimation accuracy may vary over time if left uncalibrated. Therefore, this study assessed the accuracy and long-term performance of an upper-arm, cuffless photoplethysmographic blood pressure monitor according to the ISO 81060-2 standard. This device was based on a nonlinear machine-learning model architecture with a fine-tuning optimized method. The blood pressure measurement protocol followed a validation procedure according to the standard, with an additional four weekly blood pressure measurements over a 1-month period, to assess the long-term performance values of the upper-arm, cuffless photoplethysmographic blood pressure monitor. The results showed that the photoplethysmographic signals obtained from the upper arm had better qualities when compared with those measured from the wrist. When compared with the cuffed blood pressure monitor, the means ± standard deviations of the difference in BP at week 1 (baseline) were -1.36 ± 7.24 and -2.11 ± 5.71 mmHg for systolic and diastolic blood pressure, respectively, which met the first criterion of ≤5 ± ≤8.0 mmHg and met the second criterion of a systolic blood pressure ≤ 6.89 mmHg and a diastolic blood pressure ≤ 6.84 mmHg. The differences in the uncalibrated blood pressure values between the test and reference blood pressure monitors measured from week 2 to week 5 remained stable and met both criteria 1 and 2 of the ISO 81060-2 standard. The upper-arm, cuffless photoplethysmographic blood pressure monitor in this study generated high-quality photoplethysmographic signals with satisfactory accuracy at both initial calibration and 1-month follow-ups. This device could be a convenient and practical tool to continuously measure blood pressure over long periods of time.

Validity and Tolerability of Awake Calibration of an Accelerometer Neuromuscular Monitor.

Validity and Tolerability of Awake Calibration of an Accelerometer Neuromuscular Monitor.

System Monitoring Calibration Oil and Gas Equipment at the Cepu Oil and Gas PPSDM Instrumentation Workshop Using Java Netbeans

Information on calibration reports of oil and gas equipment at the Instrumentation Workshop at the Cepu Oil and Gas Human Resources Development Center (PPSDM Migas) is still not real time, and the filing of reports is still manual in a special cabinet. Often constrained in the process of searching for documents, and confusing information on repair status and recalibration schedule. The purpose of this study was to develop a Calibration Monitoring System for Oil and Gas Equipment at the Instrumentation Workshop at PPSDM Migas Cepu, to facilitate monitoring of the calibration process, search for data, reduce paper usage, and update information on equipment repair status. Research data from calibration reports in 2017 were 113 and in 2018 there were 79 reports. Using UML (Unified Modeling Language) modeling and Java Netbeans programming language. The results of the research are a monitoring system for equipment calibration at the Instrumentation workshop, and it has been tested functionally with blackbox testing, 97% successful in accordance with its function.

Ozone Monitoring Instrument (OMI) collection 4: establishing a 17-year-long series of detrended level-1b data

Abstract. The Ozone Monitoring Instrument (OMI) was launched on 15 July 2004, with an expected mission lifetime of 5 years. After more than 17 years in orbit the instrument is still functioning satisfactorily and in principle can continue doing so until the expected decommissioning of its platform Aura in 2025. In order to continue the datasets acquired by OMI and the Microwave Limb Sounder, the mission was extended up to at least 2023. Actions have been taken to ensure the proper functioning of the OMI operations, the data processing, and the calibration monitoring system until the eventual end of the mission. For the data processing a new level-0 (L0) to level-1b (L1b) data processor was built based on the recent developments for the TROPOspheric Monitoring Instrument (TROPOMI). With corrections for the degradation of the instrument now included, it is feasible to generate a new data collection to supersede the current collection-3 data products and reprocess the data of the entire mission up to now. This paper describes the differences between the collection-3 and collection-4 data. It will be shown that the collection-4 L1b data comprise a clear improvement with respect to the previous collections. By correcting for the gentle optical and electronic aging that has occurred over the past 17 years, OMI's ability to make trend-quality ozone measurements has further improved.

Dose-Area Product Determination and Beam Monitor Calibration for the Fixed Beam of the Shanghai Advanced Proton Therapy Facility

Research conducted to-date, makes use of the IBA-Lynx scintillating screen and radiochromic film to analyze the proton field uniformity for dose-area product (DAP) determination. In this paper, the machine log file based reconstruction is proposed to calculate the field uniformity to simplify the measurement. In order to calculate the field uniformity, the dose distribution is reconstructed based on the machine log file with matRad (an open source software for analytical dose calculation in MATLAB). After acquisition of the dose distribution, the field flatness and symmetry are calculated automatically for different proton energies. A comprehensive comparison of DAP determined with Bragg peak chamber (BPC) and Markus chamber (MC) is presented. The actual delivered dose is reconstructed with the log file to analyze the lateral dose distribution of the scanned field. DAP of different energies are calculated ranging from 70.6 MeV to 235 MeV. The percentage difference is calculated, illustrating the DAP discrepancy between the MC and BPC to the mean value. The percentage difference ranges from −0.19% to 1.26%. The variation between DAP measured with the BPC and MC peaks at −2.5%. The log file based reconstruction to calculate field uniformity can be an alternative for DAP determination. The direct method using a large-area Bragg peak chamber is investigated. The two methods to determine DAP and calibrate beam monitor illustrate consistent results.

INCU Analyzer for Infant Incubator Based on Android Application Using Bluetooth Communication to Improve Calibration Monitoring

Worldwide, over 4 million babies die within a month of birth each year. Of these, 3.9 million are in developing countries. A proportion approximately 25% of these deaths are due to complications of premature birth, most commonly inadequate thermoregulation, water loss, and neonatal jaundice. An infant incubator provides stable temperature, relative humidity, and airflow values. A periodical calibration should be applied on infant incubator to monitor the functionality. The study aims to develop a calibration device that measures temperature, humidity, airflow, and noise in the baby incubator based on an Android application with Bluetooth communication to improve the calibration monitoring process. This is to achieve a better performance of the conventional INCU analyzer. The contribution of this research is that the values of the temperature, humidity, airflow, and noise can be displayed on both devices, the INCU analyzer machine, and mobile phone; thus, the user can monitor the measurement activities wirelessly. Furthermore, the statistical calculation for all measurements can be saved on a mobile phone device. The main design consists of temperature sensor LM35, humidity sensor DHT22, airflow sensor MPX5010DP, an analog signal conditioning circuit, an Arduino Mega microcontroller, Bluetooth module HC05, and Android mobile phone. The resulting design was compared to the standard or calibrator INCU analyzer machine (Fluke Biomedical INCU II). This study found that the smallest error is -1.72%°C, -0.106 % RH, -1.727% dB, and <0.1% m/s for temperature, humidity, noise, and airflow parameters, respectively. After the evaluation process, this device can be used as an INCU analyzer to calibrate the infant incubator.

Three-way calibration checks using ground-based, ship-based, and spaceborne radars

Abstract. This study uses ship-based weather radar observations collected from research vessel Investigator to evaluate the Australian weather radar network calibration monitoring technique that uses spaceborne radar observations from the NASA Global Precipitation Mission (GPM). Quantitative operational applications such as rainfall and hail nowcasting require a calibration accuracy of ±1 dB for radars of the Australian network covering capital cities. Seven ground-based radars along the western coast of Australia and the ship-based OceanPOL radar are first calibrated independently using GPM radar overpasses over a 3-month period. The calibration difference between the OceanPOL radar (used as a moving reference for the second step of the study) and each of the seven operational radars is then estimated using collocated, gridded, radar observations to quantify the accuracy of the GPM technique. For all seven radars the calibration difference with the ship radar lies within ±0.5 dB, therefore fulfilling the 1 dB requirement. This result validates the concept of using the GPM spaceborne radar observations to calibrate national weather radar networks (provided that the spaceborne radar maintains a high calibration accuracy). The analysis of the day-to-day and hourly variability of calibration differences between the OceanPOL and Darwin (Berrimah) radars also demonstrates that quantitative comparisons of gridded radar observations can accurately track daily and hourly calibration differences between pairs of operational radars with overlapping coverage (daily and hourly standard deviations of ∼ 0.3 and ∼ 1 dB, respectively).

A scalable, self‐supervised calibration and confounder removal model for opportunistic monitoring of road degradation

AbstractAssessing road degradation typically requires specialized hardware (such as laser profilometers) or labor‐intensive visual inspection. To facilitate large‐scale, timely inspection of road surfaces, opportunistic sensing is proposed: Sound and vibration measurements are obtained from vehicles that are on the road for other purposes than measuring road quality. Prior work has addressed the problem of calibration and measurement noise removal from this abundance of measurements for a small number of measurement vehicles that drive on the same roads. However, as the deployment of opportunistic monitoring progresses, the applied techniques suffer from scalability. Here, a scalable self‐supervised calibration and confounder removal (SCCR) algorithm is introduced. It allows to self‐calibrate even if the data collection is done in distinct geographic areas and is capable of generalizing to vehicles not encountered during the training phase. Several model design alternatives are explored. After the application of SCCR, supervised training on a small subset of roads allows to predict observations made by standardized techniques also in areas where the latter have not been performed. The approach is tested and validated with 41 cars driving on 23,000 km of roads.

Measurement method of spindle motion error based on composite laser target

The primary component of ultra-precision machining machines and measuring instruments is a high-precision spindle, and spindle error affects the accuracy of these machines. Traditional spindle error measurement methods often require a standard device as a reference, which inevitably reduces the accuracy of spindle error measurement, while the error separation technique is tedious and time-consuming. This study proposed a spindle error measurement method based on a composite laser target, which can measure the motion error of the spindle, including axial, radial, and tilt error in terms of five degrees of freedom. In this method, a composite laser target containing a laser point source and laser collimated beam was constructed and mounted on the spindle as a reference frame to mark the position of the spindle during rotation. Consequently, the error of the spindle was obtained via measurements of the position and angle of the composite laser target. Differential confocal microscopy technique was employed for measuring the axial position of the laser point source to obtain the axial error of the spindle, whereas the radial position was measured using a conventional microscope optical path to obtain the radial error of the spindle. Further, the angle of laser collimation was measured using a collimation measurement optical path to obtain the tilt error of the spindle. The measurement resolution of the proposed method for spindle error was verified through suitable experiments, yielding resolutions of 4 and 2 nm for axial and radial errors, respectively, and 0.2 μrad in case of tilt error. In addition, the method was tested on an air spindle to demonstrate the feasibility of using the method on machines. Thus, it was demonstrated that the proposed method can be used to obtain the spindle error by optical standard devices without additional error separation techniques, particularly for a spindle in ultra-high precision measurement equipment. Further, it facilitates real time monitoring or evaluation and calibration of the spindle error. This method is expected to serve several important practical applications in the field of ultra-precision machining and measurement. • Spindle error measurement method based on a composite laser target proposed. • Method eliminates reliance of accuracy on standard device used. • Motion error of spindle: axial, radial, tilt in terms of five degrees of freedom. • Resolution of proposed method verified through suitable experiments. • Practical applications in the field of ultra-precision machining and measurement.

Methodology for checking the stability of the Cesium-137 irradiator system of the Radiation Monitors Calibration Laboratory (LabCal) at IDQBRN / Metodologia para verificar a estabilidade do sistema de irradiação Césio-137 do Laboratório de Calibração de Monitores de Radiação (LabCal) no IDQBRN

The provision for the Brazilian Army of equipment that provides reliable and safe measurements leads to the need for a metrology study of the calibration system used in the Institute's Radiation Monitor Calibration Laboratory (LabCal) of Chemical, Biological, Radiological and Nuclear Defense (IDQBRN). In order to verify the stability of dosimetry in Cesium-137, the ambient dose equivalent rate, H*(10), was experimentally obtained for certain distance settings and lead attenuators at different dates in order to compare them. To this end, the distance between the source of Cesium-137 and the ionization chamber was varied from 1000, 2000 and 3000 mm without attenuator and with lead attenuators with 15 and 32 mm. In this work, the reproducibility of the system was analyzed by comparing the scenario of equal distance and attenuator, but with a different test date. For this purpose, the correction due to the radioactive decay of the source up to a reference date was used for comparison.Furthermore,the stability of the LabCal in Cesium-137 was verified in the light of the relevant standards for exposures without attenuators and with select attenuators for the tested distances.

X-ray beam monitoring and wavelength calibration using four-beam diffraction.

Rigorous dynamical theory calculations show that four-beam diffraction (4BD) can be activated only by a unique photon energy and a unique incidence direction. Thus, 4BD may be used to precisely calibrate X-ray photon energies and beam positions. Based on the principles that the forbidden-reflection 4BD pattern, which is typically an X-shaped cross, can be generated by instant imaging using the divergent beam from a point source without rocking the crystal, a detailed real-time high-resolution beam (and source) position monitoring scheme is illustrated for monitoring two-dimensional beam positions and directions of modern synchrotron light sources, X-ray free-electron lasers and nano-focused X-ray sources.

Monitoring the Performance of HY-2B and Jason-2/3 Sea Surface Height via the China Altimetry Calibration Cooperation Plan

Calibration and validation (Cal/Val) of the sea surface height as measured by satellite radar altimeters is essential to understand altimeter biases, observation trends, and instrument aging. It also supports the long-term stability of the produced climate change records of sea level as determined by altimetry. In this article, we report the calibration of HY-2B and Jason-2/3 using the established research infrastructure and data sharing initiative introduced by the Altimetry Calibration Cooperation Plan (ACCP) of China. Currently, three ACCP calibration sites encompass the Wanshan Islands, and two national oceanic sites are located along the China coastline. For each Cal/Val site, the components of the facilities&#x2014;the geodetic, sea level, and Global Navigation Satellite System (GNSS) infrastructure&#x2014;and the followed monitoring procedures and calibration methods are described. The HY-2B performance was primarily evaluated using about two years data, which indicated a mean bias of &#x2212;0.2 &#x00B1; 4.2 cm. Confidence in the results is strong, because the HY-2B biases were cross compared and confirmed by all the three independent sites and the three satellite ground tracks. Compared with its predecessor HY-2A, HY-2B shows very stable observations with no linear drift at present. In addition, Jason-2 and Jason-3 were mainly assessed using Qianliyan site. Our results indicate that the Jason-3 sea-surface height bias is approximately 2&#x2013;3 cm smaller than that of Jason-2 and that the long-term stability of Jason-2/3 shows no significant trend, which in good agreement with the international dedicated sites. The instrument noises of Jason-2/3 and HY-2B were estimated based on the ACCP sites. The results show that the instrument noise in the previous literature is underestimated. This was also consolidated by the result from wavenumber spectrum and global crossover point analysis. The code and Wanshan data used in these Cal/Val experiments are publicly available to facilitate further work in this domain (<uri>https://github.com/GenericAltimetryTools/CalAlti</uri>).