ESR and TL dosimetry systems: comparative measurements for human phantom

Mixtures of small fragments on tooth enamel as well as thermoluminescence (TL) dosimeters were placed into the tissue-equivalent phantom of the human head with skeleton (approximately at the level of the jaws) and irradiated using ¹³⁷Cs low dose-rate gamma therapeutic sources (‘SELEKTRON’ LDR ¹³⁷Cs). Phantom, samples of teeth and TL detectors were irradiated behind water tank to produce scattered irradiation. The same irradiation with the same geometry was performed in air too. For gamma-spectrometry ¹³⁷Cs sources with very low activity were used but with the same geometry as therapeutic sources. The absorbed dose in enamel was estimated with the help of ESR spectrometer ‘ESP-300 E’ (Brucker). The samples of tooth enamel were partially used for preliminary dose evaluation by ESR signal before starting of experiment. TL dosimetry was performed by TL reader model 8800 (HARSHAW) using TL dosimeters calibrated with ¹³⁷Cs. The paper presents data obtained in comparative aspects.     

ESR dosimetry of a deceased radiation worker

A case of overexposure of an industrial radiographer using ¹⁹²Ir sources and having a filmbadge dosimeter record of 104 mSv has been examined with ESR dosimetry of postmortem tooth and bone specimens. ESR measurements of the tooth enamel showed an intense signal of CO₂⁻ and gave the equivalent dose (ED) of 14 Gy by the additive dose method using γ-rays from a source of ⁶⁰Co. The doses for a finger bone and humerus were 14.7 and 7.0 Gy, respectively. It was concluded that he had been exposed to radiation repeatedly over 10 yr and that ESR dosimetry can give a life-long cumulative dose for personnel using radiation.     

Influence of sample treatment on ESR signal of irradiated citrus

ESR spectra of the hard seed cover and kernel coating of irradiated orange and tangerin fruits were obtained under different sample drying conditions to analyze the effect of treatment on ESR line at g + 2.0033 (line A). The spectra shows almost the same lines that appear in stalks, achenes, seeds and skins of fresh fruit. The peak-to-peak intensity of the line A of the spectra shows a linear variation with dose in the range studied (up to 5 kGy) under controlled sample preparation. Q-band ESR spectra shows that this line is composed for three different lines from different species, A₁, A₂ and A₃. The A₂ and A₃ lines are associated with dose but grow also during drying of the sample and are probably due to ‘cellulosic’ components of the seed cover. The A₁ line appears only when sample is dried and is probably associated with the quinones of the internal kernel coat.     

Relationships between ESR-evaluated doses estimated from enamel and activity of radionuclides in bone and teeth of reindeer.

Doses of radiation estimated from ESR analysis of tooth enamel were compared with activities of alpha- and beta-emitters in enamel and in bone tissue of mandibles of 77 reindeer from populations with different levels of radiation contamination. Contribution of the radionuclides incorporated into bone (or bone-seeking radionuclides in food) to ESR-evaluated doses was substantial and the contribution of the radionuclides incorporated into enamel itself proved to be relatively small.     

用牙釉电子自旋共振方法估算慢性辐射损伤人员的受照剂量

目的 用于牙釉电子自旋共振对慢性辐射损伤人员的受照剂量进行估算的方法。方法 用电子自旋共振仪测定慢性辐射损伤人员牙釉电子自旋共振信号强度，用剂量－效应曲线法和附加剂量法来重建辐射损伤人员的受照剂量，探讨牙釉电子自旋共振法估算受照剂量的可行性；并比较了不同能量的射线（1.25MeV的γ射线和6MeV的X射线）对牙釉电子自旋共振信号强度的影响。结果 用两种方法估算的辐射损伤人员受照剂量基本一致；对能量1.25MeV的γ射线和6MeV的X射线进行比较，无论从剂量－效应曲线的直线系数，还是用混合照射后的剂量估算，两者差别不大。结论 慢性辐射损伤人员的受照剂量可以用于牙釉电子自旋共振方法进行估算，射线能量在1.25MeV-6MeV范围内对牙釉电子自旋共振信号强度影响不大。     

Identification of irradiated mangoes by means of ESR spectroscopy

Samples of mango varieties Tommy Atkins, Haiden and Ataulfo were irradiated with ⁶⁰Co gamma radiation at doses in the range 0.15–1.0 kGy, and stored at room temperature for lapses of time up to 72 h. They were then studied by ESR spectrometry. Results show that the ESR signal of the irradiated samples is higher than that of the unirradiated samples, and this is found even at the minimum radiation dose of 0.15 kGy. The ESR signal remained stable during the storage time. The ESR signal obtained for hydroheated mangoes show insignificant differences with respect to the control samples.     

ESR detection of irradiated seashells

Among the protocols for identification of irradiated foodstuffs submitted to the European Committe of Standardization, two using ESR (food containing bone or cellulose) were finally accepted as official ‘draft European standards’ in Berlin on 9–10 June 1994. We present here some new results for oyster and mussel shells, and an ESR draft protol is proposed.     

日射量的估算及其对牙釉质电子自旋共振剂量学的影响

目的 探讨日射量的估算方法及太阳光辐射对牙釉质电子自旋共振(ESR)剂量学的影响。方法 用机械方法获得11个牙釉质样品。用照度计测量太阳光的照度,通过比较日本气象厅在广岛市测得的瞬时日射量和相同时刻所测得的照度,计算出转换系数,然后估算出照射在牙釉质样品的累积日射量。用⁶⁰⁶⁰Co γ射线和太阳光分别照射牙釉质样品,使用ESR波谱仪测量不同辐射后牙釉质样品的ESR信号。结果 照度与瞬时日射量的转换系数为(8.67±0.22) W·m^-2klx。照射在牙釉质样品上的累积日射量为(580±16) MJm²。太阳光辐射也引起γ射线照射产生的剂量学信号,而且随累积日射量而线性增强,太阳光辐射还产生一个紧邻本底的信号,当累积日射量大于某一值时,该信号趋于饱和状态。结论 用剂量学信号对所受辐射剂量进行评价,本研究中每MJm²的太阳光辐射的影响相当于(7.7±1.4) mGy的γ射线辐射。紧邻本底的ESR信号可作为太阳光辐射的标志峰,有助于判断所收集的样品是否受到太阳光辐射,从而提高小剂量重建的准确度。     

不同制备方法对牙釉质样品ESR信号的影响

目的研究不同制备方法对牙釉质样品ESR信号的影响，有效地提高牙釉质样品ESR剂量学的灵敏度。方法对无放射线照射史成年人臼齿分别用化学、机械以及机械加化学方法进行处理，制备牙釉质样品。利用电子自旋共振仪测定不同制备方法处理的样品在^60Coγ射线照射不同剂量后的ESR信号。比较分析其灵敏度，从而寻求一种对牙釉质样品ESR信号影响较小的样品制备及处理方法。结果不同方法处理的牙釉质样品的ESR信号，对^60Coγ射线的响应有较明显的差异。结论利用牙釉质ESR剂量学重建受照人员剂量时，尤其是使用附加照射法进行较低剂量重建时，选择合适的样品制备方法是十分重要的。     

山羊牙釉质电子自旋共振的剂量学特性

目的 探讨山羊牙釉质电子自旋共振(ESR)的剂量学的特性.方法 采用机械和化学处理相结合的方法,制备5组不同年龄的山羊牙釉质样品.用137 Cs γ射线照射山羊牙釉质样品,使用ESR波谱仪测量辐射前和不同辐射剂量后不同牙釉质样品的ESR信号.结果 137Cs γ射线照射前,山羊牙釉质所固有的ESR本底信号平均值为21.5,明显低于人的平均本底强度水平39.5;与人牙釉质相同,山羊牙釉质照射后产生的剂量学信号的强度与照射剂量线性相关,5组100 mg山羊牙釉质样品,其剂量学峰的辐射灵敏度的平均值为(34.3±1.9)/Gy,与人牙釉质样品的辐射响应平均值36.3/Gy非常接近.结论 人类牙釉质样品缺乏时,可以用相同辐射环境中的山羊牙釉质作为替代品进行剂量重建,为正确地评价辐射事故剂量提供科学依据.

Abstract：

Objectlve To study the properties of goat tooth enamel electron spin resonance (ESR)dosimetry.Methods Tootll enamel samples of goats were achieved by combined mechanical and chemical treatment at the ages of l,2,3,5,and 6 years.respectively and 9 enamel samples of adult molar were obtained.These enamel samples were exposed to 137Cs γ-rays at the cumulative doses of 0,0.5,1.0,2.0,and 5.0 Gy,respectively.ESR spectra Was measured before and after exposure.Results The background signal of goat tooth samples W88 21.5,significantly lower than that of the adult molar samples(39.5).The dusimetric signal intensity of the goat enamel increased with the radiation dose in a linear manner just as that of the human molars.The average radiation sensitivity of the goat tooth samples was(34.3±1.9)/Gy,close to that of the human tooth samples.Conclusions Goat teeth can be used for retrospective radiation dose reconstruction when human teeth are unavailable,in order to previde scientific data for dose reconstruction accurately.     

Formation of E′1 precursors in quartz: applications to dosimetry and dating

We studied the formation of E′₁ precursors in quartz of diverse origin using electron spin resonance. We found that after annealing at 600°C the natural E′₁ signal level could be regenerated by heavy gamma radiation plus another heat treatment. The formation process exhibited temperature dependence. We concluded that this dependence might affect our ability to date quartz, but also that signal regeneration can now be applied to obtain minimum ages for Phanerozoic igneous and vein quartz.     

C hyperfine interactions of CO2 in irradiated tooth enamel as studied by EPR

The EPR spectrum of tooth enamel caused by ¹³C hyperfine interactions of the CO₂⁻ radical were studied on γ-irradiated powdered samples annealed for 40 min at different temperatures up to 250°C. The lineshape and hyperfine splitting of the spectra were found to depend on the annealing temperature. Experimental spectra were compared with calculated ones assuming that EPR spectra are formed by two CO₂⁻ species—axial (rotating) and orthorhombic (braked) radicals. We assumed that the axial CO₂⁻ radicals are centers located in perfect areas of the hydroxyapatite crystals of tooth enamel whereas the orthorhombic CO₂⁻ radicals are rotating centers which are braked by defects. The thermal treatment of enamel samples leads to defective annealing and transformation of the orthorhombic centers into axial ones. This results in an increasing axial CO₂⁻ radical contribution to the EPR spectrum with increase of annealing temperature.     

Role extension and role advancement – Is there a difference? A discussion paper

The terms ‘extended’ and ‘advanced’ practice are commonly used to describe clinical practitioner roles. However, these terms have not been clearly defined within the context of modern radiography practice despite their fundamental importance to establishing the 4 tier structure, implementing Agenda for Change and promoting a coherent clinical radiography career structure. This paper discusses the terms ‘extension’ and ‘advancement’ in relation to radiography practice and, using evidence from the debates of other health professions, attempts to offer some clarity to the terminology, presenting one interpretation of its possible application to the radiographer role in the United Kingdom.     

Augmentation de la fréquence d’apparition de l’hypoxémie induite par l’exercice chez des rameurs de haut-niveau

Objectifs. – Évaluer la fréquence d’apparition de l’hypoxémie induite par l’exercice (HIE) chez un groupe de rameurs de haut-niveau.Méthodes. – Sept rameurs de haut-niveau ont participé à l’étude (19,14 ± 1,3 ans). Les sujets ont effectué une épreuve d’effort à charge croissante sur un rameur ergométrique lors de laquelle les échanges gazeux et la saturation de l’hémoglobine en oxygène (SpO₂) ont été mesurés.Résultats. – Les sujets avaient une VO₂max de 61,68 ± 1,65 ml/min par kilogramme. Tous ont présenté une HIE avec des chutes de SpO₂ comprises entre 5 et 11 %. Cette chute était significative dès 70 % VO₂max. Le volume d’entraînement réduit des athlètes testés par rapport aux autres athlètes endurants semble indiquer que le phénomène est indépendant du volume d’entraînement.Conclusion. – Cette étude a permis de mettre en évidence que 100 % des rameurs de haut-niveau présentaient une HIE. La limitation ventilatoire et l’importante masse musculaire mise en jeu spécifiques à l’aviron seraient les hypothèses explicatives.Aim. – To access the frequency of exercise-induced hypoxemia (EIH) in elite oarsmen.Method. – Seven elite oarsmen participated (19.14 ± 1.3 year) in this study. Subjects performed an incremental exercise testing on a rowing ergometer. Gas exchanges and pulse oxymetric saturation in oxygen (SpO₂) were measured during exercise.Results. – Subjects exhibited a mean of VO₂max of 61.68 ± 1.65 ml min^–1 kg^–1. All rowers showed an EIH with a SpO₂ ranging between 5% and 11%. This SpO₂ fall was significant from 70% VO₂max. The reduced training volume of our athletes compared with others endurance trained athletes seems indicate that phenomenon is not dependent of training volume.Conclusion. – This study showed that 100% of elite oarsmen exhibit EIH. Mechanical limitation in ventilation and great muscle mass involved in rowing could be the explicative hypothesis.     

Validation du Sport Tester PE 3000 en fonction de l'enregistrement Holter

This study aims to validate the measurements of heart frequency (FC) as obtained both with the ‘Sport Tester PE 3000’ and the new ‘Long Range Telemetry PE 3000’ with respect to the same measurements recorded with the ‘Holter’ ECG as reference values. Twenty subjects were submitted to a variable 50 min work-out. The heart frequency was measured every 15 sec simultaneously with the three instruments. The telemetric device could be applied to only ten subjects. The results show that the choice of apparatus had no significant influence on the heart rate registration, with high correlations and unsignificant difference between the three types of measurement.In conclusion, the Sport Tester PE 3000 and its long range telemetry system are valid alternatives on field and for research purposes for the fragile and unwieldy Holter apparatus.     

The spatial distribution of ESR signals in fault gouge revealed by Abrading technique

The spatial distribution of ESR signal intensity and equivalent dose (D_E) has been predicted within the quartz grains from fault gouge by the localized lattice deformation and frictional heating theory (Lee and Schwarcz, 1994). The abrading technique was applied to a fault gouge sample in order to see the distribution as the technique removes the surface semi-quantitatively. Both intensities of E′₁ and Al centers become larger after abrasion, being consistent with the theory, but not all the D_ES.     

An ESR study of defects in irradiated hydroxyapatite

Radiation-induced defects in synthetic hydroxyapatite (HAp) of six different origins have been investigated by electron spin resonance (ESR), X-ray diffraction (XRD), Raman scattering and IR measurements. The orthorhombic CO₂⁻ radicals were detected in almost of all the samples examined, but the isotropic CO₂⁻ was produced only in water-containing HAp with low crystallinity. The doublet signal due to H⁰ was clearly detected in HAp with extreme calcium deficiency as compared to the stoichiometry. The results of ESR and FTIR suggest that water molecules in low crystalline HAp are not on the surface but embedded in the HAp crystalline lattice.     

ESR studies and ESR dating of quartz

In this work we have investigated quartz grains which were extracted from ignimbrites in Kapadokya, using ESR spectroscopy techniques. It was found from the ESR spectra of the natural quartz that Al and Ti centers were responsible for the observed ESR lines. Their calculated g-factors were found to be g₁ = 2.07, g₂ = 2.01 for the Al center and g = 1.93 for the Ti center. Thermal behavior of these centers were examined by making isothermal and isochronic annealing experiments. It was shown from these experiments that Ti centers were more stable than the Al centers. Signal growth curves due to the γ-irradiation helped us to estimate the ADs (acquired doses) and the ages of the quartz grains. We have determined the age of the quartz grains to be 1.2 Ma with an error factor of 22%, which falls into the Pliocene epoch in the time scale.     

ESR study of Na-colloids in heavily irradiated NaCl: Size effects and inter-precipitate interactions

Compared with other materials, the radiolysis processes in alkali halides and in particular NaCl have been investigated extensively. From these investigations we have obtained a rather clear picture of the radiolysis processes in these model materials. During irradiation of NaCl crystals at 50–150°C Na and Cl₂ precipitates are formed. At low doses the F-center ESR signal and the optical F-band are found. With increasing dose a rapid transition from F and F-aggregates to colloids occurs. We have observed colloids showing Curie paramagnetism, a Curie-Pauli cross-over (both due to size effects) and normal Pauli behavior. In heavily damaged samples we have observed anomalous behavior of the intensity and line-width as a function of temperature. Our observations have important consequences for the understanding of the radiolysis processes in heavily damaged NaCl.