Eurados review of retrospective dosimetry techniques for internal exposures to ionising radiation and their applications

This work presents an overview of the applications of retrospective dosimetry techniques in case of incorporation of radionuclides. The fact that internal exposures are characterized by a spatially inhomogeneous irradiation of the body, which is potentially prolonged over large periods and variable over time, is particularly problematic for biological and electron paramagnetic resonance (EPR) dosimetry methods when compared with external exposures. The paper gives initially specific information about internal dosimetry methods, the most common cytogenetic techniques used in biological dosimetry and EPR dosimetry applied to tooth enamel. Based on real-case scenarios, dose estimates obtained from bioassay data as well as with biological and/or EPR dosimetry are compared and critically discussed. In most of the scenarios presented, concomitant external exposures were responsible for the greater portion of the received dose. As no assay is available which can discriminate between radiation of different types and different LETs on the basis of the type of damage induced, it is not possible to infer from these studies specific conclusions valid for incorporated radionuclides alone. The biological dosimetry assays and EPR techniques proved to be most applicable in cases when the radionuclides are almost homogeneously distributed in the body. No compelling evidence was obtained in other cases of extremely inhomogeneous distribution. Retrospective dosimetry needs to be optimized and further developed in order to be able to deal with real exposure cases, where a mixture of both external and internal exposures will be encountered most of the times.

Characterization of the NIST seaweed Standard Reference Material

The National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) for seaweed was developed through an interlaboratory comparison with 24 participants from 16 countries. After evaluating different techniques to calculate certified values for the radionuclides, the median method was found to be the most representative technique. The certified values were provided for 13 radionuclides and information values were given for 15 more radionuclides. Results for the natural decay series showed disequilibrium in both the uranium and thorium series.

The relationship between personality and attainment in 16-19-year-old students in a sixth form college. I: Construction of the Student Self-Perception Scale

BACKGROUND

Of the research that has been undertaken into the relationship between personality and attainment, relatively little exists relating to the 16-19 age range. In a substantive study examining the relationship between academic self-concept, attainment and personality in sixth form students, a first requirement was to design a self-perception instrument.

AIMS

The psychometric element of the study aimed to construct a Student Self-Perception Scale (SSPS) that would be effective for students in the FE (further education) context.

SAMPLES

The samples comprised a pilot sample of 152 students (aged 16-17 years from two sixth from colleges) and a main sample of 364 students (mean age, 16yrs 10mths, range 16:0 to 18:6 years, from one sixth form college). The main sample included similar numbers of male and female students (46% male, 54% female) and ethnic minority students comprised 14% of this sample.

METHOD

An initial item pool of 88 four-point Likert type statements was compiled from comparable existing scales and from responses to a Student Induction Questionnaire. Item analysis was based on oblique factor analysis of the pilot sample responses, followed by cross-validation on the main sample to refine the scale structures. Construct validity was established from the substantive study, especially the Nowicki & Strickland (1973) locus of control results.

RESULTS

Exploration of the four- and five-factor structures led to a final specification based on 52 items from five oblique factors. The constituent scales were Passivity (12 items, alpha = .81). Mastery (15 items, alpha = .79), Work Related Inadequacy (11 items, alpha = .72), Extraversion (4 items, alpha = .70) and Social Dependence (10 items, alpha = .66), all statistics compiled from the cross-validation sample. Correlations with Locus of Control ranged from 0.52 for Mastery to -.34 for Work Related Inadequacy. Distribution statistics for Locus of Control matched a comparable American sample.

CONCLUSIONS

The five-scale structure exhibits good cross-validation characteristics and supports revealing analyses of relationships within the substantive study. Its 52-item format is suitable for research or exploratory use within its intended FE context.

The relationship between personality and attainment in 16-19-year-old students in a sixth form college: II: Self-perception, gender and attainment

BACKGROUND

A related paper (Summerfield & Youngman, 1999) has described the development of a scale, the Student Self-Perception Scale (SSPS) designed to explore the relationship between academic self-concept, attainment and personality in sixth form college students.

AIMS

The study aimed to identify groups of students exhibiting varying patterns of relationship using a range of measures including the SSPS. Issues of gender and also examined.

SAMPLES

The samples comprised a pilot sample of 152 students (aged 16-17 years from two sixth form colleges) and a main sample of 364 students (mean age, 16 yrs 10 mths range 16:0 to 18:6 years, from one sixth form college). The main sample included similar numbers of male and female students (46% male, 54% female) and ethnic minority students comprised 14% of this sample.

METHOD

Data comprised responses to two personality measures (the SSPS, Summerfield, 1995, and the Nowicki-Strickland Locus of Control Scale, Nowicki & Strickland, 1973), various student and tutor estimates of success, and performance data from college records. Students were classified using relocation cluster analysis and cluster differences verified using discriminant function analysis. Thirty outcome models were tested using covariance regression analysis.

RESULTS

Eight distinct and interpretable groups, consistent with other research, were identified but the hypothesis of a positive, linear relationship between mastery and academic attainment was not sustained without qualification. Previous attainment was the major determinant of final performance. Gender variations were detected on the personality measures, particularly Confidence of outcomes, Prediction discrepancy, Passivity, Mastery, Dependency and Locus of control, and these were implicated in the cluster characteristics.

CONCLUSIONS

The results suggest that a non-linear methodology may be required to isolate relationships between self-concept, personality and attainment, especially where gender effects may exist.