The structure of anxiety and depression in a normative sample of younger and older Australian adolescents.

It has been reported that depression and anxiety have overlapping symptoms and are conceptually interrelated. One of the most prominent theoretical developments that explain this association is Clark and Watson's tripartite model (Journal of Abnormal Psychology, 100:316-336, 1991) that posits these two disorders and negative emotions share a latent component of negative affect (NA). The current study had two aims, (a) to compare a tripartite factor structure against competing models by Confirmatory Factor Analysis (CFA) of the Depression Anxiety and Stress Scales (DASS-21) (Lovibond and Lovibond 1995), and (b) explore the psychometric properties of the DASS-21. The DASS-21 was completed by a representative sample of 4039 young Australians, aged 12-18 years, as part of the South Australian Youth Mental Health Survey (SAYMHS), South Australia, Australia. The best fitting model for the data consisted of anhedonic depression, physiological hyperarousal, and general NA. The psychometric properties of the DASS-21 were excellent with a stable and interpretable factor structure and good internal consistency. The results of the current study suggest that the theoretical tripartite structure of depression and anxiety is robust and applicable among Australian youth. The diagnostic, clinical and theoretical implications of these findings are discussed.

A preliminary study of the novel application of normoxic polymer gel dosimeters for the measurement of CTDI on diagnostic x-ray CT scanners.

Computer tomography dose index (CTDI) is a measurement undertaken during acceptance testing and subsequent quality assurance measurements of diagnostic x-ray CT scanners for the determination of patient dose. Normoxic polymer gel dosimeters have been used for the first time to measure dose and subsequently CTDI during acceptance testing of a CT scanner and compared with the conventional ionization chamber measurement for a range of imaging protocols. The normoxic polymer gel dosimeter was additionally used to simultaneously determine slice-width dose profiles and CTDI in the transaxial plane, the measurements of which are usually determined with thermoluminescent dosimetry or film. The resulting CTDI for all slice widths calculated from the normoxic polymer gel dosimeter were within corresponding ionization chamber CTDI values. Slice-width dose-profiles full-width half-maximum values from the normoxic polymer gel dosimeter were compared to the slice sensitivity profiles and were within the tolerances of the manufacturer. Normoxic polymer gel dosimeters have been shown to be a useful device for determining CTDI and dose distributions for CT equipment, and provide additional information not possible with just the use of an ionization chamber.