Research and development activities in electron paramagnetic resonance dosimetry

Desrosiers, Marc F.; Burlinska, G.; Kuppusamy, Periannan; Zweíer, Jay L.; Yaczko, D M.; Auteri, F. P.; McClelland, M; Dick, C. E.; McLaughlin, W.L.

doi:10.1016/0969-806x(95)00351-w

Cited by 11 publications

(4 citation statements)

References 2 publications

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“…Though no significant change in the EPR spectrum was measurable at high doses compared to low doses, low-intensity signal contributions to the overall spectrum from secondary or tertiary radicals could not be ruled out. Early experimental studies using photo-bleaching [ 16 ] and spin-trapping [ 17 ] of irradiated alanine were able to detect spectroscopically different radicals at high doses. Later, advances in EPR spectral analysis identified a secondary radical and postulated the existence of a third [ 18 ].…”

Section: The Alanine Dosimeter Dose/dose-rate Effectmentioning

confidence: 99%

An absorbed-dose/dose-rate dependence for the alanine-EPR dosimetry system and its implications in high-dose ionizing radiation metrology

Mf¹,

Jm²,

Sl³

2008

J. Res. Natl. Inst. Stand. Technol.

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NIST developed the alanine dosimetry system in the early 1990s to replace radiochromic dye film dosimeters. Later in the decade the alanine system was firmly established as a transfer service for high-dose radiation dosimetry and an integral part of the internal calibration scheme supporting these services. Over the course of the last decade, routine monitoring of the system revealed a small but significant observation that, after examination, led to the characterization of a previously unknown absorbed-dose-dependent, dose-rate effect for the alanine system. Though the potential impact of this effect is anticipated to be extremely limited for NIST’s customer-based transfer dosimetry service, much greater implications may be realized for international measurement comparisons between National Measurement Institutes.

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Section: The Alanine Dosimeter Dose/dose-rate Effectmentioning

confidence: 99%

An absorbed-dose/dose-rate dependence for the alanine-EPR dosimetry system and its implications in high-dose ionizing radiation metrology

Mf¹,

Jm²,

Sl³

2008

J. Res. Natl. Inst. Stand. Technol.

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“…Numerous electron paramagnetic resonance (EPR) studies have been performed on radiation-induced free radicals in carbohydrates in the last decades. Motivations for studying this type of systems include dosimetric applications, − a better understanding of the consequences of radiation treatment of different sugar-containing foodstuffs, − and increased insight in the radiation chemistry of more complex, carbohydrate-containing biomolecules like DNA. − In spite of their apparent simplicity, carbohydrates exhibit a remarkably complex radiation chemistry and investigating the radiation-induced radical structures and reaction mechanisms in these compounds is relevant in elucidating phenomena of fundamental importance, like radiation regioselectivity (i.e., the tendency of radiation to inflict damage preferentially at certain sites in a molecule).…”

Section: Introductionmentioning

confidence: 99%

Radiation Products at 77 K in Trehalose Single Crystals: EMR and DFT Analysis

et al. 2012

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The radicals obtained in trehalose dihydrate single crystals after 77 K X-irradiation have been investigated at the same temperature using X-band electron paramagnetic resonance (EPR), electron nuclear double resonance (ENDOR), and ENDOR-induced EPR (EIE) techniques. Five proton hyperfine coupling tensors were unambiguously determined from the ENDOR measurements and assigned to three carbon-centered radical species (T1, T1*, and T2) based on the EIE spectra. EPR angular variations revealed the presence of four additional alkoxy radical species (T3 to T6) and allowed determination of their g tensors. Using periodic density functional theory (DFT) calculations, T1/T1*, T2, and T3 were identified as H-loss species centered at C4, C1', and O2', respectively. The T4 radical is proposed to have the unpaired electron at O4, but considerable discrepancies between experimental and calculated HFC values indicate it is not simply the (net) H-loss species. No suitable models were found for T5 and T6. These exhibit a markedly larger g anisotropy than T3 and T4, which were not reproduced by any of our DFT calculations.

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“…For example, the post-irradiation response of the alanine system is most stable at 1 kGy or less [ 12 ] and the dose rate effect on the alanine response is nonexistent or insignificant at 1 kGy but measurable at 10 kGy and up [ 11 ]. It has been postulated that the alanine response may be more influenced by the presence of secondary free radicals in the dose ranges above several kGy [ 11 , 13 ]. Therefore, the study began at the 1 kGy level where the alanine dosimeter response can be considered less susceptible to influence quantities commonly experienced in radiation processing.…”

Section: Resultsmentioning

confidence: 99%

A Comparison of Harwell & FWT Alanine Temperature Coefficients From 25 °C to 80 °C

Desrosiers

Forney

Puhl

2012

J. Res. Natl. Inst. Stand. Technol.

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The dosimeters used to monitor industrial irradiation processing commonly experience significant temperature rises that must be considered in the dose analysis stage. The irradiation-temperature coefficient for a dosimetry system is derived from the dosimeter’s radiation response to the absorbed dose and the irradiation temperature. This temperature coefficient is typically expressed in percent change per degree. The temperature rise in dosimeters irradiated with high-intensity ionizing radiation sources can be appreciable. This is especially true for electron-beam processing in which dosimeter temperatures can approach 80 °C. A recent National Institute of Standards and Technology (NIST) study revealed modest (0.5 % to 1.0 %) deviations from the predicted value at temperatures above 70 °C for absorbed doses of 1 kGy and 20 kGy. However, these data were inconsistent with a concurrent manuscript published by National Physical Laboratory (NPL) researchers that found a significant dose-dependent non-linear alanine response but used dosimeters from a different manufacturer and a different experimental design. The current work was undertaken to reconcile the two studies. Alanine dosimeters from each manufacturer used by NIST and NPL were co-irradiated over a wide range of absorbed dose and irradiation temperature. It was found that though there was a slight variation in the temperature coefficient between the two alanine dosimeter sources both systems were linear with irradiation temperature up to 70 °C and the NPL observations of non-linearity were not reproduced. These data confirmed that there is no fundamental difference in the two commercial alanine dosimeter sources and that temperature corrections could be made on industrial irradiations at the extremes of irradiation temperature and absorbed dose.

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Research and development activities in electron paramagnetic resonance dosimetry

Cited by 11 publications

References 2 publications

An absorbed-dose/dose-rate dependence for the alanine-EPR dosimetry system and its implications in high-dose ionizing radiation metrology

An absorbed-dose/dose-rate dependence for the alanine-EPR dosimetry system and its implications in high-dose ionizing radiation metrology

Radiation Products at 77 K in Trehalose Single Crystals: EMR and DFT Analysis

A Comparison of Harwell & FWT Alanine Temperature Coefficients From 25 °C to 80 °C

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