Figure - available from: Radiation and Environmental Biophysics
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MwP saturation of I2 (closed circle) and the spin-flip satellite lines (closed triangle) of GA-m (inset detailed view of the spin-flip satellite lines)
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In the present work, spectroscopic features of the radiation-induced radicals of gallic acid compounds were investigated using electron paramagnetic resonance (EPR) spectroscopy. While un-irradiated samples presented no EPR signal, irradiated samples exhibited an EPR spectrum consisting of an intense resonance line at the center and weak lines on b...
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Citations
... However, as a result of irradiation, the structure of the drug may be impaired (physical change and chemical degradation), and radiation induced radicals may have adverse effects on human health. For these reasons, not only to determine the dosimetric properties but also to identify and characterize the radical is especially important for drugs (Damian, 2003;Ambroz et al., 2000;Raffi et al., 2002;Aleksieva and Yordanov, 2012;Onori et al., 1996;Koseoglu et al., 2003;Tuner, 2017). ...
In this study, radiation effect on an asthma drug Airfix and its ingredients (Montelukast sodium, Sorbitol) were analyzed by using EPR spectroscopy in the dose range of 10 Gy–30 kGy. The dependence of radiation-induced radicals on irradiation dose, temperature and time was investigated in detail. It has been determined that the radical observed predominantly in the Airfix structure originates from Sorbitol, and the characteristic features of this alkyl-type radical have been clearly defined using both experimental EPR and theoretical DFT methods. Dosimetric properties were investigated for all samples and it was suggested that Airfix drug and Sorbitol could be used as an EPR dosimeter through this radical agent which was determined to be very stable and sensitive to radiation. Moreover, it has been emphasized that other drugs containing Sorbitol excipient can also be used for dosimetric purposes in the dose range studied and even irradiation doses can be detected in case of radiation sterilization.
... Recently, efforts have been made to improve the sensitivity of ESR dosimetry below 1 Gy (Alzimami et al. 2014). Various materials have been investigated such as ammonium tartrate, ammonium formate, potassium tartrate hemihydrate, lithium formate, dithionates, taurine, glasses, sodium tartrate dihydrate, strontium sulphate, gallic acid and watch glasses (Acar et al. 2016;Gustafsson et al. 2004Gustafsson et al. , 2008Bartolotta et al. 2011;Lund et al. 2005;Marrale et al. 2006Marrale et al. , 2007Marrale et al. , 2009Marrale et al. , 2011aTuner and Kayikçi 2012;Maghraby et al. 2012;Tuner 2017). Another approach aimed to increase the sensitivity to various types of ionising radiation is the addition of dopants such as gold, gadolinium, or silver in small concentrations (to avoid the loss of tissue equivalence) (Brai et al. 2007a;Guidelli and Baffa 2014;Guidelli et al. 2012;Marrale et al. 2008aMarrale et al. , b, 2011bMarrale et al. , 2015cSmith et al. 2015Smith et al. , 2017. ...
This work deals with the dosimetric features of a particular phenolic compound (IRGANOX 1076®) for dosimetry of clinical photon beams by using electron spin resonance (ESR) spectroscopy. After the optimization of the ESR readout parameters (namely modulation amplitude and microwave power) to maximise the signal without excessive spectrum distortions, basic dosimetric properties of laboratory-made phenolic dosimeters in pellet form, such as reproducibility, dose–response, sensitivity, linearity and dose rate dependence were investigated. The dosimeters were tested by measuring the depth dose profile of a 6 MV photon beam. A satisfactory intra-batch reproducibility of the ESR signal of the manufactured dosimeters was obtained. The ESR signal proved to increase linearly with increasing dose in the investigated dose range 1–13 Gy. The presence of an intrinsic background signal limits the minimum detectable dose to a value of approximately 0.6 Gy. Reliable and accurate assessment of the dose was achieved, independently of the dose rate. Such characteristics, together with the fact that IRGANOX 1076® is almost tissue-equivalent, and the stability of the ESR signal, make these dosimeters promising materials for ESR dosimetric applications in radiotherapy.
... Bu durumun GA-m molekülünün yapısında bulunan su molekülünün etkisiyle oluştuğu düşünülmektedir. Işınlanan GA örneklerin EPR spektroskopik özellikleri literatürde ayrıntılı olarak tartışılmıştır [8]. ...
In the present work, temperature effects of gamma irradiated anhydrous and monohydrate gallic acid components were investigated using Electron Paramagnetic Resonance (EPR) spectroscopy. While unirradiated samples presented no EPR signal, irradiated samples were observed to exhibit an EPR spectrum consisting of an intense resonance line at the middle and weak lines on both sides. Thermal features of the radicals responsible of experimental EPR spectrum were explored trough the variations of the peak-to-peak amplitude and spectrum area under the EPR spectra. Also the high temperature annealing stability of the radicals was investigated. It is calculated that the activation energies of the main two radicals that contributed to the experimental spectra of GA-a and GA-m compounds was 64.68 kJ/mol and 88.11 kJ/mol, and 35.88 kJ / mol and 127.64 kJ/mol, respectively.
The effect of gamma radiation on lithium trifluoromethanesulfonate (LiTf) was investigated in detail using electron spin resonance (ESR) spectroscopy. The experimental spectra consisted of complex overlapped signals. Simulations of both the 1st- and 10th-day ESR spectra gave valuable information about the spectroscopic and structural features of radiation-induced radicals. More information about the qualitative and quantitative features of the radicals were gathered from the microwave power, storage time and dosimetric feature findings. In the light of the information obtained, four radicals were accepted to be produced after irradiation of LiTf.
