Characterization of lithium formate EPR dosimeters for high dose applications - Comparison with alanine

Einar Waldeland, Jakob Helt-Hansen, Erik Malinen

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Lithium formate and l-α-alanine (alanine) EPR dosimeters were irradiated to doses from 100 Gy to 100 kGy. The irradiations were mainly performed at a Gammacell irradiator with dose rate of approximately 5.5 kGy h-1. Both the peak-to-peak amplitude of the first derivative EPR spectrum and the area under the EPR absorption spectrum were extracted, and the resulting dose dependence of these EPR signal intensity parameters was analyzed. The dependence of the peak-to-peak width of the central resonance in the first derivative EPR spectrum on the dose was also elucidated. In addition, the dependence on dose rate and irradiation temperature for the two materials were measured. Dosimeters were given doses from 100 Gy to 10 kGy at two different Gammacells with dose rates of 5.5 kGy h-1 and 0.6 kGy h-1, respectively, and the results were compared. Furthermore, the EPR signal intensities for dosimeters irradiated to 1 kGy at temperatures from 11 °C to 40 °C were analyzed. By fitting an 'exponential rise to maximum'-function to the dependence of the area under the EPR absorption spectrum on the dose, saturation doses of 53 kGy and 87 kGy for lithium formate and alanine, respectively, were found. Lower estimates were found when analyzing the dose dependence of the peak-to-peak amplitude. Furthermore, the peak-to-peak width was found to increase for doses above 10 kGy. No dose rate dependence for any of the studied materials was observed and the temperature coefficients at 25 °C (i.e. change in dosimeter signal per °C change in irradiation temperature) were 0.154% K-1 and 0.161% K-1 for lithium formate and alanine, respectively. This work demonstrates that lithium formate EPR dosimeters may be suitable for high dose applications, but their signals saturate at lower doses than alanine. The saturation doses found for both materials may be used in theoretical calculations of the dosimeter response following hadron beam irradiations.

Original languageEnglish (US)
Pages (from-to)213-218
Number of pages6
JournalRadiation Measurements
Volume46
Issue number2
DOIs
StatePublished - Jan 1 2011

Fingerprint

Dosimeters
formates
alanine
Dosimetry
dosimeters
Paramagnetic resonance
Lithium
lithium
dosage
Irradiation
Absorption spectra
Derivatives
irradiation
Temperature
absorption spectra
saturation
temperature

Keywords

  • Alanine
  • Dose rate
  • Dosimeters
  • Dosimetry
  • EPR
  • ESR
  • Electron paramagnetic resonance
  • Gammacell
  • High dose
  • Lithium formate
  • Photons
  • Radiotherapy
  • Temperature
  • Temperature coefficient

ASJC Scopus subject areas

  • Radiation
  • Instrumentation

Cite this

Characterization of lithium formate EPR dosimeters for high dose applications - Comparison with alanine. / Waldeland, Einar; Helt-Hansen, Jakob; Malinen, Erik.

In: Radiation Measurements, Vol. 46, No. 2, 01.01.2011, p. 213-218.

Research output: Contribution to journalArticle

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abstract = "Lithium formate and l-α-alanine (alanine) EPR dosimeters were irradiated to doses from 100 Gy to 100 kGy. The irradiations were mainly performed at a Gammacell irradiator with dose rate of approximately 5.5 kGy h-1. Both the peak-to-peak amplitude of the first derivative EPR spectrum and the area under the EPR absorption spectrum were extracted, and the resulting dose dependence of these EPR signal intensity parameters was analyzed. The dependence of the peak-to-peak width of the central resonance in the first derivative EPR spectrum on the dose was also elucidated. In addition, the dependence on dose rate and irradiation temperature for the two materials were measured. Dosimeters were given doses from 100 Gy to 10 kGy at two different Gammacells with dose rates of 5.5 kGy h-1 and 0.6 kGy h-1, respectively, and the results were compared. Furthermore, the EPR signal intensities for dosimeters irradiated to 1 kGy at temperatures from 11 °C to 40 °C were analyzed. By fitting an 'exponential rise to maximum'-function to the dependence of the area under the EPR absorption spectrum on the dose, saturation doses of 53 kGy and 87 kGy for lithium formate and alanine, respectively, were found. Lower estimates were found when analyzing the dose dependence of the peak-to-peak amplitude. Furthermore, the peak-to-peak width was found to increase for doses above 10 kGy. No dose rate dependence for any of the studied materials was observed and the temperature coefficients at 25 °C (i.e. change in dosimeter signal per °C change in irradiation temperature) were 0.154{\%} K-1 and 0.161{\%} K-1 for lithium formate and alanine, respectively. This work demonstrates that lithium formate EPR dosimeters may be suitable for high dose applications, but their signals saturate at lower doses than alanine. The saturation doses found for both materials may be used in theoretical calculations of the dosimeter response following hadron beam irradiations.",
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N2 - Lithium formate and l-α-alanine (alanine) EPR dosimeters were irradiated to doses from 100 Gy to 100 kGy. The irradiations were mainly performed at a Gammacell irradiator with dose rate of approximately 5.5 kGy h-1. Both the peak-to-peak amplitude of the first derivative EPR spectrum and the area under the EPR absorption spectrum were extracted, and the resulting dose dependence of these EPR signal intensity parameters was analyzed. The dependence of the peak-to-peak width of the central resonance in the first derivative EPR spectrum on the dose was also elucidated. In addition, the dependence on dose rate and irradiation temperature for the two materials were measured. Dosimeters were given doses from 100 Gy to 10 kGy at two different Gammacells with dose rates of 5.5 kGy h-1 and 0.6 kGy h-1, respectively, and the results were compared. Furthermore, the EPR signal intensities for dosimeters irradiated to 1 kGy at temperatures from 11 °C to 40 °C were analyzed. By fitting an 'exponential rise to maximum'-function to the dependence of the area under the EPR absorption spectrum on the dose, saturation doses of 53 kGy and 87 kGy for lithium formate and alanine, respectively, were found. Lower estimates were found when analyzing the dose dependence of the peak-to-peak amplitude. Furthermore, the peak-to-peak width was found to increase for doses above 10 kGy. No dose rate dependence for any of the studied materials was observed and the temperature coefficients at 25 °C (i.e. change in dosimeter signal per °C change in irradiation temperature) were 0.154% K-1 and 0.161% K-1 for lithium formate and alanine, respectively. This work demonstrates that lithium formate EPR dosimeters may be suitable for high dose applications, but their signals saturate at lower doses than alanine. The saturation doses found for both materials may be used in theoretical calculations of the dosimeter response following hadron beam irradiations.

AB - Lithium formate and l-α-alanine (alanine) EPR dosimeters were irradiated to doses from 100 Gy to 100 kGy. The irradiations were mainly performed at a Gammacell irradiator with dose rate of approximately 5.5 kGy h-1. Both the peak-to-peak amplitude of the first derivative EPR spectrum and the area under the EPR absorption spectrum were extracted, and the resulting dose dependence of these EPR signal intensity parameters was analyzed. The dependence of the peak-to-peak width of the central resonance in the first derivative EPR spectrum on the dose was also elucidated. In addition, the dependence on dose rate and irradiation temperature for the two materials were measured. Dosimeters were given doses from 100 Gy to 10 kGy at two different Gammacells with dose rates of 5.5 kGy h-1 and 0.6 kGy h-1, respectively, and the results were compared. Furthermore, the EPR signal intensities for dosimeters irradiated to 1 kGy at temperatures from 11 °C to 40 °C were analyzed. By fitting an 'exponential rise to maximum'-function to the dependence of the area under the EPR absorption spectrum on the dose, saturation doses of 53 kGy and 87 kGy for lithium formate and alanine, respectively, were found. Lower estimates were found when analyzing the dose dependence of the peak-to-peak amplitude. Furthermore, the peak-to-peak width was found to increase for doses above 10 kGy. No dose rate dependence for any of the studied materials was observed and the temperature coefficients at 25 °C (i.e. change in dosimeter signal per °C change in irradiation temperature) were 0.154% K-1 and 0.161% K-1 for lithium formate and alanine, respectively. This work demonstrates that lithium formate EPR dosimeters may be suitable for high dose applications, but their signals saturate at lower doses than alanine. The saturation doses found for both materials may be used in theoretical calculations of the dosimeter response following hadron beam irradiations.

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