Basic investigations on the performance of a normoxic polymer gel with tetrakis‐hydroxy‐methyl‐phosphonium chloride as an oxygen scavenger: Reproducibility, accuracy, stability, and dose rate dependence

Bayreder, Christian; Georg, Dietmar; Moser, Ewald; Berg, Andreas

doi:10.1118/1.2208741

Cited by 39 publications

(36 citation statements)

References 49 publications

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“…In these cases, the rate of beam damage likely overwhelms any structural recovery that occurs. Materials of the latter type usually include some ionic materials,75–78 such as transition metal oxides (TMOs)75 and fluorides,76,77 of which the beam damage effects are strongly dependent on the dose rate. For materials with increased radiation sensitivity upon elevated dose rate, a “direct” dose‐rate effect is attributed, which in some cases arises from the poor electrical conductivity and accumulated charging 57.…”

Section: Physical Origin and Behavior Of Electron Beam Damagementioning

confidence: 99%

Imaging Beam‐Sensitive Materials by Electron Microscopy

et al. 2020

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Electron microscopy allows the extraction of multidimensional spatiotemporally correlated structural information of diverse materials down to atomic resolution, which is essential for figuring out their structureproperty relationships. Unfortunately, the high-energy electrons that carry this important information can cause damage by modulating the structures of the materials. This has become a significant problem concerning the recent boost in materials science applications of a wide range of beam-sensitive materials, including metal-organic frameworks, covalent-organic frameworks, organicinorganic hybrid materials, 2D materials, and zeolites. To this end, developing electron microscopy techniques that minimize the electron beam damage for the extraction of intrinsic structural information turns out to be a compelling but challenging need. This article provides a comprehensive review on the revolutionary strategies toward the electron microscopic imaging of beamsensitive materials and associated materials science discoveries, based on the principles of electron-matter interaction and mechanisms of electron beam damage. Finally, perspectives and future trends in this field are put forward. he worked as a postdoctoral fellow and research scientist at King Abdullah University of Science and Technology. His research interests now focus on low-dose electron microscopy and structural elucidation of beam-sensitive materials for applications such as catalysis, gas separation, and energy conversion/storage.

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Section: Physical Origin and Behavior Of Electron Beam Damagementioning

confidence: 99%

Imaging Beam‐Sensitive Materials by Electron Microscopy

et al. 2020

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“…suppressed gradually as the dose rate increases. As long as the dose rate dependence is caused by the incident trajectory congestion, this effect is observed even in the irradiation of photon beam (Bayreder et al, 2006). This model is also applied to interpret the evidence of the variation in the efficiency of dose rate dependence as to the depth (Fig.…”

Section: Discussionmentioning

confidence: 96%

“…We prepared MAGAT type polymer gel detector (Bayreder et al, 2006) for this study. The recent studies have demonstrated that other polymer gel detectors, for example the PAG gel which compose of acrylamide with N,N 0 -methylene-bis-acrylamide as the monomer, had the advantages over the MAGAT gel in the various radiation properties such as the dependence on the dose rate and the dose integration (De Deene et al, 2006;Karlsson et al, 2007), nevertheless the MAGAT gel has over ten times steeper gradient in the doseeresponse relations than PAG gel's gradient, which is to advantage in the depth dose measurements.…”

Section: Polymer Gel Preparationmentioning

confidence: 99%

Examination of fundamental characteristics of a polymer gel detector in a proton beam irradiation

Yoshioka

Tominaga

Usui

et al. 2011

Radiation Measurements

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“…The accuracy is less than achievable by ionization chambers. Our preliminary test exposures have shown that MRPD especially designed for higher spatial resolution 14,15 is sensitive to the extraordinary high dose rates at several hundreds of Gy/s as present in MRT and thus offer yet unsatisfying results concerning dose response and spatial resolution. …”

Section: Mri Gel Dosimetrymentioning

confidence: 99%

Potential High Resolution Dosimeters For MRT

Bräuer-Krisch¹,

Rosenfeld²,

Lerch³

et al. 2010

AIP Conference Proceedings

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Abstract. Microbeam Radiation Therapy (MRT) uses highly collimated, quasi-parallel arrays of X-ray microbeams of 50-600 keV, produced by 2 nd and 3 rd generation synchrotron sources, such as the National Synchrotron Light Source (NSLS) in the U.S., and the European Synchrotron Radiation Facility (ESRF) in France, respectively. High dose rates are necessary to deliver therapeutic doses in microscopic volumes, to avoid spreading of the microbeams by cardiosynchronous movement of the tissues. A small beam divergence and a filtered white beam spectrum in the energy range between 30 and 250 keV results in the advantage of steep dose gradients with a sharper penumbra than that produced in conventional radiotherapy. MRT research over the past 20 years has allowed a vast number of results from preclinical trials on different animal models, including mice, rats, piglets and rabbits. Microbeams in the range between 10 and 100 micron width show an unprecedented sparing of normal radiosensitive tissues as well as preferential damage to malignant tumor tissues. Typically, MRT uses arrays of narrow (~25-100 micron-wide) microplanar beams separated by wider (100-400 microns centre-to-centre, c-t-c) microplanar spaces. We note that thicker microbeams of 0.1-0.68 mm used by investigators at the NSLS are still called microbeams, although some invesigators in the community prefer to call them minibeams. This report, however, limits it discussion to 25-100 µm microbeams. Peak entrance doses of several hundreds of Gy are surprisingly well tolerated by normal tissues. High resolution dosimetry has been developed over the last two decades, but typical dose ranges are adapted to dose delivery in conventional Radiation Therapy (RT). Spatial resolution in the sub-millimetric range has been achieved, which is currently required for quality assurance measurements in Gamma-knife RT. Most typical commercially available detectors are not suitable for MRT applications at a dose rate of 16000 Gy/s, micron resolution and a dose range over several orders of magnitude. This paper will give an overview of all dosimeters tested in the past at the ESRF with their advantages and drawbacks. These detectors comprise: Ionization chambers, Alanine Dosimeters, MOSFET detectors, Gafchromic ® films, Radiochromic polymers, TLDs, Polymer gels, Fluorescent Nuclear Track Detectors (Al 2 O 3 :C, Mg single crystal detectors), OSL detectors and Floating Gate-based dosimetry system. The aim of such a comparison shall help with a decision on which of these approaches is most suitable for high resolution dose measurements in MRT. The principle of these detectors will be presented including a comparison for some dosimeters exposed with the same irradiation geometry, namely a 1×1 cm 2 field size with microbeam exposures at the surface, 0.1 cm and 1 cm in depth of a PMMA phantom. For these test exposures, the most relevant irradiation parameters for future clinical trials have been chosen: 50 micron FWHM and 400 micron c-t-c distance. The experimental data are compared w...

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Basic investigations on the performance of a normoxic polymer gel with tetrakis‐hydroxy‐methyl‐phosphonium chloride as an oxygen scavenger: Reproducibility, accuracy, stability, and dose rate dependence

Cited by 39 publications

References 49 publications

Imaging Beam‐Sensitive Materials by Electron Microscopy

Imaging Beam‐Sensitive Materials by Electron Microscopy

Examination of fundamental characteristics of a polymer gel detector in a proton beam irradiation

Potential High Resolution Dosimeters For MRT

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