scholarly journals A new quartz for 𝛾-transfer calibration of radiation sources

2020 ◽  
Vol 47 (1) ◽  
pp. 23-34
Author(s):  
D. Richter ◽  
C. Woda ◽  
K. Dornich
Keyword(s):  
Absorbed Dose ◽  
Dose Calculations ◽  
Preheat Temperature ◽  
Aeolian Sand ◽  
Fine Grain ◽  
Radiation Sources ◽  
Pre Treatment ◽  
Additional Support ◽  
Quartz Grains ◽  
Initial Results

AbstractQuartz grains extracted from aeolian sand (LexCal2014) are tested for suitability as transfer material for radiation source calibration. After thermal pre-treatment, this quartz exhibits luminescence and dose-response properties which appear appropriate for transfer calibration purposes with little dependence of recovered β-dose on preheat temperature in the single aliquot (SAR) procedure and satisfying performance in β-dose recovery (0.98−1.00 given/measured β-dose for various experiments). Additional support is obtained by SARA and interpolation procedures, where OSL-data from γ-dosed LexCal2014 is interpolated on data obtained for zeroed LexCal2014 quartz, which is β-irradiated by the source to be calibrated. Initial results on fine-grain material agree with the coarse grain results presented.The γ-dose of 3.00 ± 0.07 Gy is administered in a scatter-free geometry at the IAEA/WHO Secondary Standard Dosimetry Laboratory (SSDL) of the Helmholtz Zentrum München, with absorbed dose calculations obtained by Monte Carlo simulations.

scholarly journals UVA-LED Technology’s Treatment Efficiency and Cost in a Competitive Trial Applied to the Photo-Fenton Treatment of Landfill Leachate

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 1026
Author(s):  
Javier Tejera ◽  
Antonio Gascó ◽  
Daphne Hermosilla ◽  
Víctor Alonso-Gomez ◽  
Carlos Negro ◽  
...  
Keyword(s):  
Landfill Leachate ◽  
Mercury Vapor ◽  
Cod Removal ◽  
Treatment Efficiency ◽  
Alternative Source ◽  
Effluent Quality ◽  
Radiation Sources ◽  
Initial Ph ◽  
Pre Treatment ◽  
Set Up

The objective of this trial was to assess the application of UVA-LED technology as an alternative source of irradiation for photo-Fenton processes, aiming to reduce treatment costs and provide a feasible treatment for landfill leachate. An optimized combination of coagulation with ferric chloride followed by photo-Fenton treatment of landfill leachate was optimized. Three different radiation sources were tested, namely, two conventional high-pressure mercury-vapor immersion lamps (100 W and 450 W) and a custom-designed 8 W 365 nm UVA-LED lamp. The proposed treatment combination resulted in very efficient degradation of landfill leachate (COD removal = 90%). The coagulation pre-treatment removed about 70% of the COD and provided the necessary amount of iron for the subsequent photo-Fenton treatment, and it further favored this process by acidifying the solution to an optimum initial pH of 2.8. The 90% removal of color improved the penetration of radiation into the medium and by extension improved treatment efficiency. The faster the Fenton reactions were, as determined by the stoichiometric optimum set-up reaction condition of [H2O2]0/COD0 = 2.125, the better were the treatment results in terms of COD removal and biodegradability enhancement because the chances to scavenge oxidant agents were limited. The 100 W lamp was the least efficient one in terms of final effluent quality and operational cost figures. UVA-LED technology, assessed as the application of an 8 W 365 nm lamp, provided competitive results in terms of COD removal, biodegradability enhancement, and operational costs (35–55%) when compared to the performance of the 450 W conventional lamp.

Uncertainty analysis of absorbed dose calculations from thermoluminescence dosimeters

1992 ◽  
Vol 19 (6) ◽  
pp. 1427-1433 ◽  
Author(s):  
T. H. Kirby ◽  
W. F. Hanson ◽  
D. A. Johnston
Keyword(s):  
Uncertainty Analysis ◽  
Absorbed Dose ◽  
Dose Calculations

The Yorkshire Dogger

1940 ◽  
Vol 77 (4) ◽  
pp. 257-275 ◽  
Author(s):  
R. H. Rastall ◽  
J. E. Hemingway
Keyword(s):  
Usual Sense ◽  
Sea Floor ◽  
Naked Eye ◽  
Bonding Material ◽  
Fine Grain ◽  
The Matrix ◽  
Interstitial Material ◽  
Bright Green ◽  
Quartz Grains

The Dogger of the coast from Peak to Kettleness is essentially a sideritic sandstone, and except in the Sandsend-Mulgrave district, is entirely unfossiliferous. This type of coast Dogger is well exposed at Hawsker Bottoms. To the naked eye it is a brownish sandstone of fine grain with very abundant white specks, a few small lenses of pale grey mudstone, and a very small number of bright green grains. Under the microscope it is seen to be a fairly well-graded sandstone with a few larger clastic elements, including both quartz and felspar as well as those mentioned above. The quartz grains are extraordinarily angular, doubtless due to corrosion by the matrix, and many of them are compound, i.e. microquartzites of various kinds. Felspar, mainly orthoclase and perthite, is abundant. A few flakes of chloritic chamosite and still more rare grains of typical speckled glauconite represent the green grains mentioned above. The matrix is somewhat oxidized, but still shows the usual well-formed rhombohedra of siderite, most of them with darker cores. The most notable point is that the sand grains rarely touch and are often widely spaced in the matrix, indicating simultaneous deposition of clastic elements and matrix, which is not a cement in the usual sense (Text-fig. 5). In this and in subsequent papers the term “ cement ” is used to connote that interstitial bonding material subsequently added to a bed of incoherent detrital grains which were lying in contact with each other before its infiltration : “ matrix ” is used for that interstitial material between detrital grains which are not in contact and which was therefore deposited contemporaneously with them, forming a part of the original sea floor deposit.

scholarly journals Assessment of MCNPX Monte Carlo Code for Absorbed Dose Calculations in Mammogarphy Examination

2017 ◽  
Vol 17 (1) ◽  
pp. 48-55 ◽  
Author(s):  
Huseyin Ozan Tekin ◽  
Asghar Mesbahi ◽  
Viswanath P. Singh ◽  
Umit Kara ◽  
Tugba Manici ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Absorbed Dose ◽  
Monte Carlo Code ◽  
Dose Calculations

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.

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