Parameters affecting EPR dose reconstruction in teeth.

The aim of this paper is to analyze the lower limit of detection (LLD), linearity of dose response, variation of radiation sensitivity between different tooth enamel samples, and time/temperature stability of EPR biodosimetry in tooth enamel. The theoretical LLD is shown to be 0.46 mGy, which is far lower than the measured value of about 30 mGy. The main issues to lowering LLD are the differentiation of the radiation-induced component against the total EPR spectrum and the complex nature of the dose dependence of the EPR signal. The following questions are also discussed in detail: need for exfoliated or extracted teeth from persons of interest, accounting for background radiation contribution; conversion of tooth enamel absorbed dose to effective dose; accounting for internal exposure specifically from bone-seeking radionuclides. Conclusions on future development of EPR retrospective biodosimetry are made.     

A mathematical model for calculation of 90Sr absorbed dose in dental tissues: elaboration and comparison to EPR measurements.

A mathematical model for calculation of the 90Sr absorbed doses in dental tissues is presented. The results of the Monte-Carlo calculations are compared to the data obtained by EPR measurements of dental tissues. Radiometric measurements of the 90Sr concentrations. TLD and EPR dosimetry investigations were performed in animal (dog) study. The importance of the irregular 90Sr distribution in the dentine for absorbed dose formation has been shown. The dominant dose formation factors (main source-tissues) were identified for the crown dentine and enamel. The model has shown agreement with experimental data which allows to determine further directions of the human tooth model development.     

Current issues on EPR dose reconstruction in tooth enamel.

This paper focuses on the opportunities to gain risk assessment information from populations exposed to ionizing radiation. Details are presented on the scale of the nuclear events in several areas within the former Soviet Union. An overview of the issues associated with dose reconstruction by electron paramagnetic resonance (EPR) is given. Principles and outline of the EPR tooth enamel dose assessment are described. Technical details, the latest achievements and the problems of each procedural step are analyzed. In addition, the present accuracy of the EPR dose reconstruction, its problems and cost are discussed.     

EPR study of radiation stability of organic plastic scintillator for cardiovascular brachytherapy Sr90-Y90 beta dosimetry.

Nowadays, more than one million percutaneous transluminal coronary angioplasties are being performed annually throughout the world. Restenosis is a significant problem associated with these angioplasty procedures. Radiation treatment with catheter-based beta-emitter sources is currently under clinical trial to prevent this problem. Due to fast and worldwide introduction of beta-sources for intravascular application, there is a growing interest in the dosimetry aspects. However, accurate dosimetry of beta-radiation is more difficult than that of gamma-radiation. Suitable detectors are not yet available with accuracy down to a tenth of a millimeter. Conventional measuring systems are not capable of such spatial resolution, except radiochromic film. However, film dosimeters have limited sensitivity and their radiation characteristics are different than those of tissue; therefore dose measurements require corrections. An alternative is to use water-equivalent plastic scintillators. In this work, organic plastic scintillator (BCF-10) dosimetry is studied using the Monte Carlo (MC) technique PENELOPE, and its radiation stability, after irradiation, is experimentally studied through electron paramagnetic resonance (EPR). Depth dose and dose profile are measured and compared to film dosimetry results. The EPR technique shows that the recovery time is dose independent in this kind of fiber and shows good stability.     

牙釉质EPR谱去卷积程序在剂量重建中的应用

目的探讨牙釉质电子顺磁共振(EPR)谱去卷积程序在小剂量区域剂量重建的应用。方法用编写的EPR谱拟合程序拟合一系列用不同小剂量照射过的牙釉质样品EPR谱，得到相应的剂量信号(RIS)强度，线性回归得到剂量响应曲线，并分析拟合精度。结果剂量响应曲线IRIS=14．04 0．768D(mGy)，r=0．997，SD=19．8mGy。结论这项技术将牙釉质EPR剂量重建的下限降低到约200mGy。     

Half-life evaluations for 3H, 90Sr, and 90Y.

A recent paper has reviewed methods for the evaluation of discrepant sets of data and demonstrated the results of applying these methods to the published half-life data of 90Sr and 137Cs [MacMahon, T.D., Pearce, A., Harris, P., 2004. Convergence of techniques for the evaluation of discrepant data. Appl. Radiat. Isot. 60, 275-281]. The half-life data for 3H has been subject to a comprehensive review and critical evaluation by Lucas and Unterweger [2000. Comprehensive review and critical evaluation of the half-life of tritium. J. Res. Natl. Inst. Stand. Technol. 105, 541-549]. The current paper reports the results of applying the various evaluation procedures of MacMahon et al. Convergence of techniques for the evaluation of discrepant data. Appl. Radiat. Isot. 60, 275-281] to the data of Lucas and Unterweger [Comprehensive review and critical evaluation of the half-life of tritium. J. Res. Natl. Inst. Stand. Technol. 105, 541-549], resulting in a recommended half-life of 4497(4) days. MacMahon et al. [Convergence of techniques for the evaluation of discrepant data. Appl. Radiat. Isot. 60, 275-281] highlighted problems in the evaluation of the discrepant half-life data of 90Sr, in particular the worrying upward trend in the data, where the weighted mean of all the measurements increases, on average, by 35 days each time a new measurement result is added. The current paper reports on further analyses of these data. New measurements of the half-life of 90Y have been reported by Kossert and Schrader [2004. Standardization by liquid scintillation counting and half-life measurements of 90Y. Appl. Radiat. Isot. 60, 741]. This has prompted a new evaluation of all available published 90Y half-life data. The data are fairly consistent, and a value of 64.063(16) h is recommended.     

90Sr敷贴器一次性大剂量治疗瘢痕疙瘩疗效评价

目的比较90Sr敷贴治疗瘢痕疙瘩一次性大剂量法和分次小剂量法的治疗效果,探讨90sr敷贴治疗一次大剂量法的临床应用价值.方法将270例患有瘢痕疙瘩的患者随机分成两组一次大剂量组和分次小剂量组分别进行治疗.结果一次大剂量组和分次小剂量组在临床治愈率、有效率和副作用发生率均无显著统计学差异,但患者明显缩短了治疗时间、节省了费用.结论90Sr敷贴一次性大剂量法治疗瘢痕疙瘩是一种省时省费的好方法,具有较高的临床应用价值.     

^90Sr敷贴器一次性大剂量治疗瘢痕疙瘩疗效评价

目的 比较^90Sr敷贴治疗瘢痕疙瘩一次性大剂量法和分次小剂量法的治疗效果，探讨^90Sr敷贴治疗一次大剂量法的临床应用价值。方法 将270例患有瘢痕疙瘩的患者随机分成两组：一次大剂量组和分次小剂量组分别进行治疗。结果 一次大剂量组和分次小剂量组在临床治愈率、有效率和副作用发生率均无显著统计学差异，但患者明显缩短了治疗时间、节省了费用。结论 ^90Sr敷贴一次性大剂量法治疗瘢痕疙瘩是一种省时省费的好方法，具有较高的临床应用价值。     

Possibility of using porcelain samples of high-voltage line insulators for radiation dose reconstruction by EPR spectroscopy

In electron paramagnetic resonance spectra of irradiated porcelain samples from high-voltage supply line insulators three overlapping single signals were observed. The dependencies of the amplitude of these signals on the microwave power, irradiation dose and the stability in darkness and in natural light were investigated. It was concluded that for dosimetric purposes it is reasonable to use the radiation-induced signal with g=2.001, which could be ascribed to the E′ centres of quartz. The microwave power dependence of the amplitude of this signal is saturated at 1 mW, the dose dependence is saturated at about 60 mGy. A minimal level of dose determination is about 1 Gy, and it is limited mainly by the accuracy of subtraction of the background signal existing in the unirradiated sample. The radiation-induced signal is stable in the darkness, but rapidly faded in natural light, therefore, for dosimetric purposes it is possible to use only insulators covered with dark glaze or ceramic samples from the very interior of the insulators.     

A rapid method for determining 89Sr and 90Sr by Cerenkov counting

A new combination of simple preparation techniques for determining ⁸⁹Sr and ⁹⁰Sr in water and milk samples using alginate has been developed and tested. By means of Cerenkov counting without a long ingrowth period for ⁹⁰Y, results can be obtained within 4 days. The detection limit is about 1 Bq/l for a sample volume of 0.2 l. Milk samples can be prepared without ashing. A Liquid Scintillation Counter TRI-Carb 3170TR/SL in low-level mode has been used for counting.     

Measurement of relative output for 90Sr ophthalmic applicators using radiochromic film.

The treatment of various superficial lesions of the eye has, for many years, been conducted using strontium 90 (90Sr) ophthalmic applicators that have a steep dose gradient near their surface. A new applicator acquired by a treatment facility must have its output compared with that of any older applicators already in use to ensure consistent treatments. These measurements may be done using available dosimeters such as film and thermoluminescent detectors. Our work made use of radiochromic film and a document scanner to perform relative output measurements for 4 different 90Sr ophthalmic applicators acquired from the same manufacturer (Amersham Healthcare, Arlington Heights, IL) over a span of 28 years. Relative outputs were found to vary by < 10% with respect to the manufacturer's values, which is well within the uncertainty limit for absolute output of 20% specified by the manufacturer. The film measurements were verified using thermoluminescent dosimeters. Radiochromic film was also used to obtain a percentage depth dose curve and a 2 dimensional isodose distribution in a plane perpendicular to the active surface for the newest applicator (SIA 20).     

Rapid method for determination of the activity concentrations of 89Sr and 90Sr

This paper describes a rapid method for determining the activity concentrations of ⁸⁹Sr and ⁹⁰Sr in air and water using LSC. After sample preparation strontium is separated by extraction chromatography. The chemical yield is determined by X-ray fluorescence. The spectra of the Čerenkov radiation and beta radiation are taken with a LSC. From both spectra the activities of strontium are calculated by means of a spectrum deconvolution method. The results can be obtained within 4.5 hours for particulate filters and 2 hours for water.     

Separation of 90Y from 90Sr using zirconium vanadate as the ion exchanger.

The sorption and desorption behaviour of several radionuclides, including 241Am, 152,154Eu, 233U, 137Cs, 90Sr and 90Y was studied under varying acidities using zirconium vanadate as ion exchanger. The sorption follows the order: Cs > Eu > Am >Y > U, while Sr was not taken up by the ion exchanger. A radiochemical separation scheme for the 90Y daughter from its 90Sr parent using zirconium vanadate ion exchanger has been developed. The exchanger was synthesized and characterized in our laboratory.     

90锶/90钇敷贴治疗增生性疤痕疙瘩疗效观察

我们对增生性疤痕疙瘩采用90锶/90钇(90Sr/90Y)敷贴和手术切除联合90Sr/90Y敷贴综合治疗,根据疤痕疙瘩生长的部位、病变大小以及病程长短等因素,选择不同照射剂量和疗效程。1资料与方法1.1临床资料增生性疤痕疙瘩患者166例,男102例,女64例,年龄9~56岁。166例中采用单纯90Sr/90Y敷贴治疗组98例,综合治疗(手术切除联合90Sr/90Y治疗)组68例。1.2方法90Sr/90Y敷贴器的表面剂量率为0.015Gy/s,采用小剂量分次治疗每次敷贴剂量4~6 GY,每周1次,3次为一疗程。综合治疗组选择增生性疤痕厚度超过0.5 cm的患者先进行手术切除,术后3~5 d即行90Sr/90…     

Evaluation of a freeze-dried kit for EDTMP-based bone-seeking radiopharmaceuticals.

A freeze-dried kit developed for formulation of ethylenediamine-tetramethylenephosphonic acid (EDTMP) chelates with "pain-palliation" radiolanthanides (e.g., 153Sm and 177Lu) or "diagnostic" 99mTc has been evaluated, meeting quality and safety criteria required for medicinal use.The EDTMP kit enables an instant one-step preparation of a radiopharmaceutical of high radiochemical purity (>99%) and has a sufficiently long shelf life. Comparative biodistribution studies of 177Lu-EDTMP and 99mTc-EDTMP prepared from the kit revealed similar tissue uptake and clearance to those obtained for pre-formulated 153Sm-EDTMP. The most significant difference was observed for 99mTc-EDTMP, which shows a high retention in kidney, reaching ca. 2% ID after 90min p.i.v.Although preliminary clinical evaluations suggest that 99mTc-EDTMP possesses limited value for bone scintigraphy, application of the radiopharmaceutical for specific diagnostic purposes may still be considered, e.g., investigation of bone metastases or ossification processes in inflammatory spondyloarthropathy.     

A new internal pair production branching ratio of 90Y: the development of a non-destructive assay for 90Y and 90Sr.

(90)Y is utilized as a therapeutic radioisotope in radiolabeled monoclonal antibodies and in microspheres for targeted radiation therapy of the liver. Currently, the widely used dose calibrator assay of (90)Y can have uncertainties exceeding +/-10%. A non-destructive assay using spectroscopy is possible by reducing the currently published uncertainty (+/-12%) in the internal pair production branching ratio for the 0(+)-0(+) transition of (90)Zr. A high-purity germanium detector was used to determine the branching ratio to be (31.86+/-0.47) x 10(-6).     

Influence of steroid hormones on the carcinogenicity of 90Sr.

Groups of female CBA-mice were given 90Sr (14.8 kBq/g-0.4muCi/g--bodyweight) alone or in combination with polyestrodiolphosphate, methylprednisolone or nortestosterone, respectively. When 90Sr was given in the first combination, the frequency of osteosarcomas was significantly increased whereas the tumour latency time was decreased compared to mice given 90Sr alone. In combination with nortestosterone such effects were not found, whereas the combination 90Sr + methylprednisolone resulted in a strong reduction of the osteosarcoma incidence and a prolonged tumour latency time. The latter experiment was repeated in a larger experiment whereby the results were confirmed.