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A Wieser

Publications and source records attributed to A Wieser.

28 records · Page 2Linked to original sources
PubMed2000

EPR dose reconstruction for Russian nuclear workers.

The present paper describes results of the first independent evaluation of the accuracy of the dose-reconstruction technique by electron paramagnetic resonance using tooth enamel. Each of twenty-four teeth donated by Mayak nuclear workers with known occupational radiation exposure histories was cut into two parts so that each tooth could be shared for blind electron paramagnetic resonance examination by at least two of the four laboratories participating in the study. The mean difference (+/- SD) between electron paramagnetic resonance estimates of the paired samples of each tooth shared by the two laboratories in best agreement was 0.02 +/- 0.15 Gy. Mayak workers can be classified into two groups: modern workers (after 1961) having reliable official dose information and earlier nuclear workers whose dose information is less reliable because they were exposed mainly before 1961. Film badges did not contain filters until 1954. Doses in this earlier group are much higher (up to 5 Gy). Comparison of the electron paramagnetic resonance results with tooth doses calculated from official film-badge doses showed a close agreement for the first group, whereas in the second group, official doses appeared to be slightly higher than the electron paramagnetic resonance doses. The results suggested a possibility that the official doses were somewhat overestimated among the high-dose-exposed workers. Consequently, cancer risks derived from this high-dose group might tend to be slightly underestimated.

Electron Spin Resonance Spectroscopy↗
PubMed1996

Pilot study of the Urals population by tooth electron paramagnetic resonance dosimetry.

During 1949-1956, about 76 x 10(6)m3 of radioactive liquid waste containing a total activity of 10(17) Bq was discharged into the Techa River by the first Russian industrial nuclear facility Mayak. As a consequence, the population living in the river valley received considerable internal and external radiation doses. The results of a first application of electron paramagnetic resonance (EPR) of tooth enamel for a retrospective individual dose evaluation of the residents of the Techa riverside are presented. Three main contributions to the dose absorbed in tooth enamel have been considered: external exposure mainly from the Techa River sediments, internal exposure mainly due to 90Sr; and background radiation including all other sources of exposure except the Techa River. The teeth of 86 inhabitants of the town Kamensk-Uralskii were analysed to determine the age-dependent contribution of the background radiation to the enamel dose. For 22 residents of the middle and lower Techa riverside, measurements of the 90Sr whole-body content and EPR measurements of the absorbed dose in enamel were used to establish a correlation between these two quantities. Finally, absorbed doses in the enamel of five residents of the upper Techa riverside were determined by EPR method. Contributions of the background radiation and the internal 90Sr contamination were subtracted to determine the external exposure of the residents.

Aged↗
PubMed1996

Selective saturation method for EPR dosimetry with tooth enamel.

The method of selective saturation proposed is based on the difference in the microwave (mw) power dependence of the background and radiation induced EPR components of the tooth enamel spectrum. The subtraction of the EPR spectrum recorded at low mw power from that recorded at higher mw power provides a considerable reduction of the background component in the spectrum. The resolution of the EPR spectrum could be improved 10-fold, however simultaneously the signal-to-noise ratio was found to be reduced twice. A detailed comparative study of reference samples with known absorbed doses was performed to demonstrate the advantage of the method. The application of the selective saturation method for EPR dosimetry with tooth enamel reduced the lower limit of EPR dosimetry to about 100 mGy.

Adolescent↗
PubMed1994

South Ural nuclear workers: comparison of individual doses from retrospective EPR dosimetry and operational personal monitoring.

As a result of EPR investigations on tooth enamel from radiation workers of the Russian nuclear facility "Mayak" in South Ural, individual doses are reconstructed. The individual doses obtained range up to 3.89 Gy. It is shown that the reconstructed doses are unreasonable until very good agreement with the original personal doses as provided by the radiation protection authority. The findings first prove the applicability of EPR dosimetry on tooth enamel for a life-time including accident dose reconstruction of individuals as a basis for epidemiological studies.

Dental Enamel↗
PubMed1985

Immune complexes and acute phase proteins in human cancer: preliminary evaluation by laser nephelometric techniques.

The serum levels of circulating immune complexes (IC) were evaluated by a new 'direct' laser nephelometric assay, concomitantly with four acute phase proteins (APP), in 167 patients with various neoplasms at different stages. The present study confirms the presence of IC in the sera of cancer patients and, in the breast cancer group, there is a significant correlation with the progression of the disease. Among the APP, in several cancer groups, C-reactive protein, haptoglobin and alpha 1-acid glycoprotein are more elevated than in controls, and a trend to display higher values is observed in the subjects with metastatic disease; particularly, the frequency of patients with 3 or more proteins above the normal levels is significantly higher in metastatic than in localized cancers (p less than 0.09).

Antigen-Antibody Complex↗
PubMedDate not supplied

Verification of occupational doses at the first nuclear plant in the former Soviet Union.

Mean annual occupational exposures are reported for radiation workers at the first Russian industrial nuclear facility 'Mayak', South Ural region, for the period 1948-1988. The underlying individual doses originate from the register of the in-plant radiation safety department and are based on local film dosimetry results. Differentiation is made between personnel working at reactor and radiochemical processing plants. Verification of summed film doses is performed by means of ESR dose reconstruction using extracted teeth from selected individuals. Explanations are given for observed discrepancies between the reconstructed individual doses and original integrated film dosimetry results. The research potential of combined dose information from specific tooth enamel and dentine are shown.

Dental Enamel↗
PubMedDate not supplied

The first international intercomparison of EPR-dosimetry with teeth: first results.

Intercomparison of EPR-dosimetric techniques using tooth enamel had been performed in order to check whether the results produced by different laboratories are consistent and accurate. Participants were supposed to evaluate doses applied to pulverized enamel samples, using routine techniques from their laboratories. The intercomparison has demonstrated a great variety of methods used for dose reconstruction. Peculiarities of experimental approaches are discussed systematically in terms of procedure for recording the EPR-spectra, determination of the amplitude of the radiation induced signal, determination of the dose, and error propagation.

Dental Enamel↗
PubMedDate not supplied

Tooth enamel as a detector material for retrospective EPR dosimetry.

Different methods of spectra evaluation and dose reconstruction in retrospective EPR dosimetry with tooth enamel have been compared in this study. Experiments with teeth irradiated with known doses have shown that dosimetry above 1 Gy using a dose effect curve is, with a standard deviation of 10%, the best method. As a second result it is shown that dosimetry down to 100 mGy with a standard deviation of 15% is possible.

Biometry↗