A blind test of the alanine dosimetry secondary standard of the PTB conducted by the BIPM

Anton, Mathias; Allisy-Roberts, P J; Kessler, C; Burns, D T

doi:10.1088/0026-1394/51/1a/06001

Cited by 4 publications

(4 citation statements)

References 16 publications

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“…This factor is known with an uncertainty of 1 % for electron energies up to 22 MeV [47]. A detailed description of PTB's alanine dosimetry system and readout of the irradiated pellets can be found elsewhere [46][47][48][49].…”

Section: Alaninementioning

confidence: 99%

Dosimetry for New Radiation Therapy Approaches Using High Energy Electron Accelerators

et al. 2020

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Section: Alaninementioning

confidence: 99%

Dosimetry for New Radiation Therapy Approaches Using High Energy Electron Accelerators

et al. 2020

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“…It was almost immediately realized that solid-state L-α-alanine is particularly interesting for dosimetric applications 4 and today it is fully recognized as a secondary radiation dose standard. [5][6][7][8] In view of this, considerable effort has been devoted to the understanding of the radiation chemistry of alanine and to reliable simulations of its powder EPR spectrum at room temperature (RT).…”

Section: Introductionmentioning

confidence: 99%

“…The first reports of the radiation-induced electron paramagnetic resonance (EPR) spectrum of this amino acid date from the early 1960s, , when alanine and other amino acids were employed to gain insight into the nature of hyperfine (HF) interactions in organic molecules. It was almost immediately realized that solid-state l -α-alanine is particularly interesting for dosimetric applications, and today it is fully recognized as a secondary radiation dose standard. − In view of this, considerable effort has been devoted to the understanding of the radiation chemistry of alanine and to reliable simulations of its powder EPR spectrum at room temperature (RT).…”

Section: Introductionmentioning

confidence: 99%

ENDOR-Induced EPR of Disordered Systems: Application to X-Irradiated Alanine

et al. 2018

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The electron paramagnetic resonance (EPR) spectra of radiation-induced radicals in organic solids are generally composed of multiple components that largely overlap due to their similar weak g anisotropy and a large number of hyperfine (HF) interactions. Such properties make these systems difficult to study using standard cw EPR spectroscopy even in single crystals. Electron-nuclear double-resonance (ENDOR) spectroscopy is a powerful and widely used complementary technique. In particular, ENDOR-induced EPR (EIE) experiments are useful for separating the overlapping contributions. In the present work, these techniques were employed to study the EPR spectrum of stable radicals in X-irradiated alanine, which is widely used in dosimetric applications. The principal values of all major proton HF interactions of the dominant radicals were determined by analyzing the magnetic field dependence of the ENDOR spectrum at 50 K, where the rotation of methyl groups is frozen. Accurate simulations of the EPR spectrum were performed after the major components were separated using an EIE analysis. As a result, new evidence in favor of the model of the second dominant radical was obtained.

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“…Further corroboration was obtained from a number of subsequent very detailed studies by others using many different radiation qualities and environmental conditions. − Today, alanine is the most used material for solid-state EPR dosimetry purposes. Extensive international dosimetry services based on EPR/alanine dosimetry are now offered by, e.g., NIST (USA), PBL (Germany), and NPL (UK). − …”

Section: Introductionmentioning

confidence: 99%

In Quest of the Alanine R3 Radical: Multivariate EPR Spectral Analyses of X-Irradiated Alanine in the Solid State

et al. 2017

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The amino acid l-α-alanine is the most commonly used material for solid-state electron paramagnetic resonance (EPR) dosimetry, due to the formation of highly stable radicals upon irradiation, with yields proportional to the radiation dose. Two major alanine radical components designated R1 and R2 have previously been uniquely characterized from EPR and electron-nuclear double resonance (ENDOR) studies as well as from quantum chemical calculations. There is also convincing experimental evidence of a third minor radical component R3, and a tentative radical structure has been suggested, even though no well-defined spectral signature has been observed experimentally. In the present study, temperature dependent EPR spectra of X-ray irradiated polycrystalline alanine were analyzed using five multivariate methods in further attempts to understand the composite nature of the alanine dosimeter EPR spectrum. Principal component analysis (PCA), maximum likelihood common factor analysis (MLCFA), independent component analysis (ICA), self-modeling mixture analysis (SMA), and multivariate curve resolution (MCR) were used to extract pure radical spectra and their fractional contributions from the experimental EPR spectra. All methods yielded spectral estimates resembling the established R1 spectrum. Furthermore, SMA and MCR consistently predicted both the established R2 spectrum and the shape of the R3 spectrum. The predicted shape of the R3 spectrum corresponded well with the proposed tentative spectrum derived from spectrum simulations. Thus, results from two independent multivariate data analysis techniques strongly support the previous evidence that three radicals are indeed present in irradiated alanine samples.

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A blind test of the alanine dosimetry secondary standard of the PTB conducted by the BIPM

Cited by 4 publications

References 16 publications

Dosimetry for New Radiation Therapy Approaches Using High Energy Electron Accelerators

Dosimetry for New Radiation Therapy Approaches Using High Energy Electron Accelerators

ENDOR-Induced EPR of Disordered Systems: Application to X-Irradiated Alanine

In Quest of the Alanine R3 Radical: Multivariate EPR Spectral Analyses of X-Irradiated Alanine in the Solid State

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