scholarly journals Optical-Radiation-Calorimeter Refinement by Virtual-Sensitivity Analysis

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1167 ◽  
Author(s):  
Lancia Hubley ◽  
Jackson Roberts ◽  
Juergen Meyer ◽  
Alicia Moggré ◽  
Steven Marsh
Keyword(s):  
Spatial Resolution ◽  
Optical Radiation ◽  
Environmental Influence ◽  
Absorbed Dose ◽  
Detector System ◽  
Optical Systems ◽  
Novel Approach ◽  
Heat Expansion ◽  
Path Lengths ◽  
The Impact

Digital holographic interferometry (DHI) radiation dosimetry has been proposed as an experimental metrology technique for measuring absorbed radiation doses to water with high spatial resolution via noninvasive optical calorimetry. The process involves digitally recording consecutive interference patterns resulting from variations in the refractive index as a function of the radiation-absorbed dose. Experiments conducted on prototype optical systems revealed the approach to be feasible but strongly dependent on environmental-influence quantities and setup configuration. A virtual dosimeter reflecting the prototype was created in a commercial optical modelling package. A number of virtual phantoms were developed to characterize the performance of the dosimeter under ideal conditions and with simulated disruptions in environmental-influence quantities, such as atmospheric and temperature perturbations as well as mechanical vibrations. Investigations into the error response revealed that slow drifts in atmospheric parameters and heat expansion caused the measured dose to vary between measurements, while atmospheric fluctuations and vibration contributed to system noise, significantly lowering the spatial resolution of the detector system. The impact of these effects was found to be largely mitigated with equalisation of the dosimeter’s reference and object path lengths, and by miniaturising the detector. Equalising path lengths resulted in a reduction of 97.5% and 96.9% in dosimetric error introduced by heat expansion and atmospheric drift, respectively, while miniaturisation of the dosimeter was found to reduce its sensitivity to vibrations and atmospheric turbulence by up to 41.7% and 54.5%, respectively. This work represents a novel approach to optical-detector refinement in which metrics from medical imaging were adapted into software and applied to a a virtual-detector system. This methodology was found to be well-suited for the optimization of a digital holographic interferometer.

scholarly journals Application of the EANM practical guidance on uncertainty analysis for MRT absorbed dose calculations on clinical cases

2020 ◽  
Author(s):  
Domenico Finocchiaro ◽  
Jonathan I Gear ◽  
Federica Fioroni ◽  
Glenn D Flux ◽  
Iain Murray ◽  
...  
Keyword(s):  
Uncertainty Analysis ◽  
Spatial Resolution ◽  
Absorbed Dose ◽  
Dose Calculations ◽  
Large Sample ◽  
Wide Range ◽  
Practical Guidance ◽  
Dose Uncertainty ◽  
The Impact ◽  
Clinical Cases

Abstract Background Internal dosimetry evaluation consists of a multi-step process ranging from imaging acquisition to absorbed dose calculations. Assessment of uncertainty is complicated and, for that reason, it is commonly ignored in clinical routine. However, it is essential for adequate interpretation of the results. Recently, the EANM published a practical guidance on uncertainty analysis for molecular radiotherapy based on the application of the law of propagation of uncertainty. In this study, we investigated the overall uncertainty on a large sample of patient following the EANM guidelines. The aim of this study was to provide an indication of the typical uncertainties that may be expected from performing dosimetry, to determine parameters that have the greatest effect on the accuracy of calculations and to consider the potential improvements that could be made if these effects were reduced. Results Absorbed doses and the relative uncertainties were calculated for a sample of 49 patients and a total of 154 tumours. A wide range of relative dose uncertainty values was observed (14 - 102%). Uncertainties associated to each quantity along the dose calculation chain (i.e. Volume, Recovery Coefficient, Calibration Factor, Activity, Time-Activity Curve Fitting, Cumulated Activity and Absorbed Dose) were estimated. An equation was derived to describe relationship between the uncertainty in the absorbed dose and the volume. The largest source of error was the VOI delineation. By postulating different values of FHWM, the impact of the imaging system spatial resolution on the uncertainties was investigated. Discussion To the best of our knowledge, this is the first analysis of uncertainty in MRT based on a large sample of clinical cases. Wide inter-lesion variability of dose uncertainty was observed. Hence, a proper assessment of the uncertainties associated with the calculations should be considered as a basic scientific standard. A model for a quick estimate of uncertainty without implementing the entire error propagation schema, which may be useful in clinical practice, was presented. Ameliorating spatial resolution may be in future the key factor for accurate absorbed dose assessment.

scholarly journals Uncertainty analysis of tumour absorbed dose calculations in molecular radiotherapy

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Domenico Finocchiaro ◽  
Jonathan I. Gear ◽  
Federica Fioroni ◽  
Glenn D. Flux ◽  
Iain Murray ◽  
...  
Keyword(s):  
Uncertainty Analysis ◽  
Spatial Resolution ◽  
Absorbed Dose ◽  
Dose Assessment ◽  
Dose Calculations ◽  
Time Activity ◽  
Molecular Radiotherapy ◽  
Wide Range ◽  
Dose Uncertainty ◽  
The Impact

Abstract Background Internal dosimetry evaluation consists of a multi-step process ranging from imaging acquisition to absorbed dose calculations. Assessment of uncertainty is complicated and, for that reason, it is commonly ignored in clinical routine. However, it is essential for adequate interpretation of the results. Recently, the EANM published a practical guidance on uncertainty analysis for molecular radiotherapy based on the application of the law of propagation of uncertainty. In this study, we investigated the overall uncertainty on a sample of a patient following the EANM guidelines. The aim of this study was to provide an indication of the typical uncertainties that may be expected from performing dosimetry, to determine parameters that have the greatest effect on the accuracy of calculations and to consider the potential improvements that could be made if these effects were reduced. Results Absorbed doses and the relative uncertainties were calculated for a sample of 49 patients and a total of 154 tumours. A wide range of relative absorbed dose uncertainty values was observed (14–102%). Uncertainties associated with each quantity along the absorbed dose calculation chain (i.e. volume, recovery coefficient, calibration factor, activity, time-activity curve fitting, time-integrated activity and absorbed dose) were estimated. An equation was derived to describe the relationship between the uncertainty in the absorbed dose and the volume. The largest source of error was the VOI delineation. By postulating different values of FWHM, the impact of the imaging system spatial resolution on the uncertainties was investigated. Discussion To the best of our knowledge, this is the first analysis of uncertainty in molecular radiotherapy based on a cohort of clinical cases. Wide inter-lesion variability of absorbed dose uncertainty was observed. Hence, a proper assessment of the uncertainties associated with the calculations should be considered as a basic scientific standard. A model for a quick estimate of uncertainty without implementing the entire error propagation schema, which may be useful in clinical practice, was presented. Ameliorating spatial resolution may be in future the key factor for accurate absorbed dose assessment.

scholarly journals Uncertainty analysis of tumour absorbed dose calculations in Molecular Radiotherapy

2020 ◽  
Author(s):  
Domenico Finocchiaro ◽  
Jonathan I Gear ◽  
Federica Fioroni ◽  
Glenn D Flux ◽  
Iain Murray ◽  
...  
Keyword(s):  
Uncertainty Analysis ◽  
Spatial Resolution ◽  
Absorbed Dose ◽  
Dose Assessment ◽  
Dose Calculations ◽  
Time Activity ◽  
Molecular Radiotherapy ◽  
Wide Range ◽  
Dose Uncertainty ◽  
The Impact

Abstract Background: Internal dosimetry evaluation consists of a multi-step process ranging from imaging acquisition to absorbed dose calculations. Assessment of uncertainty is complicated and, for that reason, it is commonly ignored in clinical routine. However, it is essential for adequate interpretation of the results. Recently, the EANM published a practical guidance on uncertainty analysis for molecular radiotherapy based on the application of the law of propagation of uncertainty. In this study, we investigated the overall uncertainty on a sample of patient following the EANM guidelines. The aim of this study was to provide an indication of the typical uncertainties that may be expected from performing dosimetry, to determine parameters that have the greatest effect on the accuracy of calculations and to consider the potential improvements that could be made if these effects were reduced.Results: Absorbed doses and the relative uncertainties were calculated for a sample of 49 patients and a total of 154 tumours. A wide range of relative absorbed dose uncertainty values was observed (14 - 102%). Uncertainties associated with each quantity along the absorbed dose calculation chain (i.e. Volume, Recovery Coefficient, Calibration Factor, Activity, Time-Activity Curve Fitting, Time-Integrated Activity and Absorbed Dose) were estimated. An equation was derived to describe relationship between the uncertainty in the absorbed dose and the volume. The largest source of error was the VOI delineation. By postulating different values of FWHM, the impact of the imaging system spatial resolution on the uncertainties was investigated.Discussion: To the best of our knowledge, this is the first analysis of uncertainty in molecular radiotherapy based on a cohort of clinical cases. Wide inter-lesion variability of absorbed dose uncertainty was observed. Hence, a proper assessment of the uncertainties associated with the calculations should be considered as a basic scientific standard. A model for a quick estimate of uncertainty without implementing the entire error propagation schema, which may be useful in clinical practice, was presented. Ameliorating spatial resolution may be in future the key factor for accurate absorbed dose assessment.

scholarly journals Uncertainty analysis of tumour absorbed dose calculations in Molecular Radiotherapy

2020 ◽  
Author(s):  
Domenico Finocchiaro ◽  
Jonathan I Gear ◽  
Federica Fioroni ◽  
Glenn D Flux ◽  
Iain Murray ◽  
...  
Keyword(s):  
Uncertainty Analysis ◽  
Spatial Resolution ◽  
Absorbed Dose ◽  
Dose Assessment ◽  
Dose Calculations ◽  
Time Activity ◽  
Molecular Radiotherapy ◽  
Wide Range ◽  
Dose Uncertainty ◽  
The Impact

Abstract Background: Internal dosimetry evaluation consists of a multi-step process ranging from imaging acquisition to absorbed dose calculations. Assessment of uncertainty is complicated and, for that reason, it is commonly ignored in clinical routine. However, it is essential for adequate interpretation of the results. Recently, the EANM published a practical guidance on uncertainty analysis for molecular radiotherapy based on the application of the law of propagation of uncertainty. In this study, we investigated the overall uncertainty on a sample of patient following the EANM guidelines. The aim of this study was to provide an indication of the typical uncertainties that may be expected from performing dosimetry, to determine parameters that have the greatest effect on the accuracy of calculations and to consider the potential improvements that could be made if these effects were reduced.Results: Absorbed doses and the relative uncertainties were calculated for a sample of 49 patients and a total of 154 tumours. A wide range of relative absorbed dose uncertainty values was observed (14 - 102%). Uncertainties associated with each quantity along the absorbed dose calculation chain (i.e. Volume, Recovery Coefficient, Calibration Factor, Activity, Time-Activity Curve Fitting, Time-Integrated Activity and Absorbed Dose) were estimated. An equation was derived to describe relationship between the uncertainty in the absorbed dose and the volume. The largest source of error was the VOI delineation. By postulating different values of FWHM, the impact of the imaging system spatial resolution on the uncertainties was investigated.Discussion: To the best of our knowledge, this is the first analysis of uncertainty in molecular radiotherapy based on a cohort of clinical cases. Wide inter-lesion variability of absorbed dose uncertainty was observed. Hence, a proper assessment of the uncertainties associated with the calculations should be considered as a basic scientific standard. A model for a quick estimate of uncertainty without implementing the entire error propagation schema, which may be useful in clinical practice, was presented. Ameliorating spatial resolution may be in future the key factor for accurate absorbed dose assessment.

scholarly journals A Monte Carlo Determination of Dose and Range Uncertainties for Preclinical Studies with a Proton Beam

Cancers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1889
Author(s):  
Arthur Bongrand ◽  
Charbel Koumeir ◽  
Daphnée Villoing ◽  
Arnaud Guertin ◽  
Ferid Haddad ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Proton Beam ◽  
Dose Response ◽  
Small Animal ◽  
Absorbed Dose ◽  
Normal Tissue Damage ◽  
Dose Homogeneity ◽  
And Control ◽  
The Impact

Proton therapy (PRT) is an irradiation technique that aims at limiting normal tissue damage while maintaining the tumor response. To study its specificities, the ARRONAX cyclotron is currently developing a preclinical structure compatible with biological experiments. A prerequisite is to identify and control uncertainties on the ARRONAX beamline, which can lead to significant biases in the observed biological results and dose–response relationships, as for any facility. This paper summarizes and quantifies the impact of uncertainty on proton range, absorbed dose, and dose homogeneity in a preclinical context of cell or small animal irradiation on the Bragg curve, using Monte Carlo simulations. All possible sources of uncertainty were investigated and discussed independently. Those with a significant impact were identified, and protocols were established to reduce their consequences. Overall, the uncertainties evaluated were similar to those from clinical practice and are considered compatible with the performance of radiobiological experiments, as well as the study of dose–response relationships on this proton beam. Another conclusion of this study is that Monte Carlo simulations can be used to help build preclinical lines in other setups.

scholarly journals Brain drain and brain gain in Russia: Analyzing international migration of researchers by discipline using Scopus bibliometric data 1996–2020

2021 ◽  
Author(s):  
Alexander Subbotin ◽  
Samin Aref
Keyword(s):  
Brain Drain ◽  
Policy Development ◽  
Donor Country ◽  
International Mobility ◽  
Science System ◽  
Migration Rates ◽  
Net Migration ◽  
Novel Approach ◽  
Five Disciplines ◽  
The Impact

AbstractWe study international mobility in academia, with a focus on the migration of published researchers to and from Russia. Using an exhaustive set of over 2.4 million Scopus publications, we analyze all researchers who have published with a Russian affiliation address in Scopus-indexed sources in 1996–2020. The migration of researchers is observed through the changes in their affiliation addresses, which altered their mode countries of affiliation across different years. While only 5.2% of these researchers were internationally mobile, they accounted for a substantial proportion of citations. Our estimates of net migration rates indicate that while Russia was a donor country in the late 1990s and early 2000s, it has experienced a relatively balanced circulation of researchers in more recent years. These findings suggest that the current trends in scholarly migration in Russia could be better framed as brain circulation, rather than as brain drain. Overall, researchers emigrating from Russia outnumbered and outperformed researchers immigrating to Russia. Our analysis on the subject categories of publication venues shows that in the past 25 years, Russia has, overall, suffered a net loss in most disciplines, and most notably in the five disciplines of neuroscience, decision sciences, mathematics, biochemistry, and pharmacology. We demonstrate the robustness of our main findings under random exclusion of data and changes in numeric parameters. Our substantive results shed light on new aspects of international mobility in academia, and on the impact of this mobility on a national science system, which have direct implications for policy development. Methodologically, our novel approach to handling big data can be adopted as a framework of analysis for studying scholarly migration in other countries.

scholarly journals Emulating Software-Defined Disaggregated Optical Networks in a Containerized Framework

2021 ◽  
Vol 11 (5) ◽  
pp. 2081
Author(s):  
Francisco-Javier Moreno-Muro ◽  
Miquel Garrich ◽  
Ignacio Iglesias-Castreño ◽  
Safaa Zahir ◽  
Pablo Pavón-Mariño
Keyword(s):  
Optical Networks ◽  
Transport Infrastructure ◽  
Optical Systems ◽  
Traffic Demand ◽  
Novel Approach ◽  
Infrastructure Project ◽  
Optical Layer ◽  
Optical Domain ◽  
Control And Management ◽  
Remote Communications

Telecom operators’ infrastructure is undergoing high pressure to keep the pace with the traffic demand generated by the societal need of remote communications, bandwidth-hungry applications, and the fulfilment of 5G requirements. Software-defined networking (SDN) entered in scene decoupling the data-plane forwarding actions from the control-plane decisions, hence boosting network programmability and innovation. Optical networks are also capitalizing on SDN benefits jointly with a disaggregation trend that holds the promise of overcoming traditional vendor-locked island limitations. In this work, we present our framework for disaggregated optical networks that leverages on SDN and container-based management for a realistic emulation of deployment scenarios. Our proposal relies on Kubernetes for the containers’ control and management, while employing the NETCONF protocol for the interaction with the light-weight software entities, i.e., agents, which govern the emulated optical devices. Remarkably, our agents’ structure relies on components that offer high versatility for accommodating the wide variety of components and systems in the optical domain. We showcase our proposal with the emulation of an 18-node European topology employing Cassini-compliant optical models, i.e., a state-of-the-art optical transponder proposed in the Telecom Infrastructure Project. The combination of our versatile framework based on containerized entities, the automatic creation of agents and the optical-layer characteristics represents a novel approach suitable for operationally complex carrier-grade transport infrastructure with SDN-based disaggregated optical systems.

scholarly journals Analysis of High-Friction Surface Texture with Respect to Friction and Wear

Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 758
Author(s):  
Cibi Pranav ◽  
Minh-Tan Do ◽  
Yi-Chang Tsai
Keyword(s):  
Friction Coefficient ◽  
Surface Texture ◽  
Safety Concern ◽  
Future Research ◽  
Scanning System ◽  
Novel Approach ◽  
Texture Parameters ◽  
Aggregate Loss ◽  
Friction Surfaces ◽  
The Impact

High Friction Surfaces (HFS) are applied to increase friction capacity on critical roadway sections, such as horizontal curves. HFS friction deterioration on these sections is a safety concern. This study deals with characterization of the aggregate loss, one of the main failure mechanisms of HFS, using texture parameters to study its relationship with friction. Tests are conducted on selected HFS spots with different aggregate loss severity levels at the National Center for Asphalt Technology (NCAT) Test Track. Friction tests are performed using a Dynamic Friction Tester (DFT). The surface texture is measured by means of a high-resolution 3D pavement scanning system (0.025 mm vertical resolution). Texture data are processed and analyzed by means of the MountainsMap software. The correlations between the DFT friction coefficient and the texture parameters confirm the impact of change in aggregates’ characteristics (including height, shape, and material volume) on friction. A novel approach to detect the HFS friction coefficient transition based on aggregate loss, inspired by previous works on the tribology of coatings, is proposed. Using the proposed approach, preliminary outcomes show it is possible to observe the rapid friction coefficient transition, similar to observations at NCAT. Perspectives for future research are presented and discussed.

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