Resolving the limitations of using glycine as EPR dosimeter in the intermediate level of gamma dose. (April 2018)

• Record Type: Journal Article
• Authors: Aboelezz, E.; Hassan, G.M.
• Is Part Of: Radiation physics and chemistry. Volume 145(2018:Apr.)
• Page Start: 5
• Page End: 10
• Publication Date: 2018-04
• Subjects: Electron spin resonance -- Dosimeter -- Glycine -- Amino acid -- Radiotherapy dose; Radiation chemistry -- Periodicals; Radiometry -- Periodicals; Radiation -- Periodicals; Chimie sous rayonnement -- Périodiques; 539.2
• DOI: 10.1016/j.radphyschem.2017.12.006
• Languages: English
• ISSNs: 0969-806X

Abstract

Abstract: The dosimetric properties of the simplest amino acid "glycine"- using EPR technique- were investigated in comparison to reference standard alanine dosimeter. The EPR spectrum of glycine at room temperature is complex, but immediately after irradiation, it appears as a triplet hyperfine structure probably due to the dominant contribution of the (CH2 COO − ) radical. The dosimetric peak of glycine is at g-factor 2.0026 ± 0.0015 and its line width is 9 G at large modulation amplitude (7 G). The optimum microwave was studied and was found to be as alanine 8 mW; the post-irradiation as well as the dose rate effects were discussed. Dosimetric peak intensity of glycine fades rapidly to be about one quarter of its original value during 20 days for dried samples and it stabilizes after that. The dose response study in an intermediate range (2–1000 Gy) reveals that the glycine SNR is about 2 times more than that of alanine pellets when measured immediately after irradiation and 4 times more than that of glycine itself after 22 days of irradiation. The effect of energy dependence was studied and interpreted theoretically by calculation of mass energy absorption coefficient. The calculated combined uncertainties for glycine and alanine are nearly the same and were found to be 2.42% and 2.33%, respectively. Glycine shows interesting dosimetric properties in the range of ionizing radiation doses investigated. Highlights: Glycine can be used as EPR dosimeter due to its powerful dosimetric properties. For direct measurement, after exposure to (2–1000 Gy) SNRglycine ≈ 2.25 SNRalanine . SNRdirectly measured alanine ≈ 2 SNRglycine after 22 days, for 2–1000 Gy range. The limitations of rapid fading and overlapped spectrum for glycine are solved. The combined uncertainty of glycine and alanine are nearly similar.