Ammonium dithionate- a new material for highly sensitive EPR dosimetry

Application of Amino Acids for High-Dosage Measurements with Electron Paramagnetic Resonance Spectroscopy

A comparative investigation of amino acids (proline, cysteine, and alanine) as dosimetric materials using electron paramagnetic resonance (EPR) spectroscopy in the absorbed dosage range of 1-25 kGy is presented. There were no signals in the EPR spectra of the samples before irradiation. After irradiation, the complex spectra were recorded. These results showed that the investigated amino acids were sensitive to radiation. In the EPR spectrum of cysteine after irradiation, RS• radicals dominated. The effects of the microwave power on the saturation of the EPR signals showed the presence of at least three different types of free radicals in proline. It was also found out that the DL-proline and cysteine had stable free radicals after irradiation and represented a linear dosage response up to 10 kGy. On the other hand, the amino acid alanine has been accepted by the International Atomic Energy Agency as a transfer standard dosimetry system. In view of this, the obtained results of the proline and cysteine studies have been compared with those of the alanine studies. The results showed that the amino acids proline and cysteine could be used as alternative dosimetric materials in lieu of alanine in a dosage range of 1-10 kGy of an absorbed dose of γ-rays using EPR spectroscopy. Regarding the radiation sensitivity, the following order of decreased dosage responses was determined: alanine > DL-proline > cysteine > L-proline.

Electron Spin Resonance Dosimetry Studies of Irradiated Sulfite Salts

The study of new materials for radiation dosimetry is important to improve the present state of the art and to help in cases of accidents for retrospective dosimetry. Sulfites are compounds that contain a sulfur ion, widely used in the food industry. Due to the significant application of these compounds, sulfites are interesting candidates for accidental dosimetry, as fortuitous radiation detectors. The presence of the SO₃⁻ anion enables its detection by electron spin resonance (ESR) spectroscopy. The Dose–Response behavior, signal stability and other spectral features were investigated for sodium sulfite, sodium bisulfite, sodium metabisulfite and potassium metabisulfite, all in crystalline forms. The ESR spectrum of salts presented stability and proportional response with dose, presenting potential for dosimetry applications.

Performance characteristics of the EPR dosimetry system with table sugar in radiotherapy applications

Performance characteristics of the megavoltage photon dose measurements with EPR and table sugar were analyzed. An advantage of sugar as a dosimetric material is its tissue equivalency. The minimal detectable dose was found to be 1.5Gy for both the 6 and 18MV photons. The dose response curves are linear up to at least 20Gy. The energy dependence of the dose response in the megavoltage energy range is very weak and probably statistically insignificant. Reproducibility of measurements of various doses in this range performed with the peak-to-peak and double-integral methods is reported. The method can be used in real-time dosimetry in radiation therapy.

Investigation of radiation sensitivity of some tartrate compounds

Potential electron spin resonance (ESR) dosimetric application of different compounds of sodium tartrate, such as sodium tartrate dihydrate, sodium bitartrate monohydrate and potassium sodium tartrate tetrahydrate, was investigated in the range of 0.74-25 Gy. While the radiation-induced intermediates produced in these compounds are similar, their radiation yields are different. It is found that the radiation yield of sodium tartrate dihydrate is higher than other compounds of sodium tartrates. Comparison of the radiation yields were also made between well-known samples of ammonium tartrate, alanine and lithium formate. It is found that the radiation yields of sodium tartrate dihydrate, sodium bitartrate monohydrate and potassium sodium tartrate tetrahydrate have the values of 1.22, 0.18 and 0.13, respectively.

LiSr4(BO3)3:Ce3+ phosphor as a new material for ESR dosimetry

LiSr4(BO3)3:0.01Ce(3+) phosphor was investigated to assess its potential as a material for measurements of radiotherapeutic doses with electron spin resonance (ESR). The ESR spectrum of the phosphor irradiated with (60)Co features five ESR signals. An isochronal annealing experiment has shown that the strongest of these signals is associated with the same trap center as the 473 K peak on the TL glow curve of this material. The dose-response is linear in the studied range from 0.89 to 90.30 Gy. Fading of the signal was also investigated.