| 1. |
|
|
| 2. |
- Fredenberg, Erik, PhD, 1979-, et al.
(författare)
-
Contrast-enhanced dual-energy subtraction imaging using electronic spectrum-splitting and multi-prism x-ray lenses
- 2008
-
Ingår i: Medical Imaging 2008 - Physics of Medical Imaging. - San Diego, CA, USA : SPIE. - 9780819470973 ; , s. 91310-91310
-
Konferensbidrag (refereegranskat)abstract
- Dual-energy subtraction imaging (DES) is a method to improve the detectability of contrast agents over a lumpy background. Two images, acquired at x-ray energies above and below an absorption edge of the agent material, are logarithmically subtracted, resulting in suppression of the signal from the tissue background and a relative enhancement of the signal from the agent. Although promising, DES is still not widely used in clinical practice. One reason may be the need for two distinctly separated x-ray spectra that are still close to the absorption edge, realized through dual exposures which may introduce motion unsharpness. In this study, electronic spectrum-splitting with a silicon-strip detector is theoretically and experimentally investigated for a mammography model with iodinated contrast agent. Comparisons are made to absorption imaging and a near-ideal detector using a signal-to-noise ratio that includes both statistical and structural noise. Similar to previous studies, heavy absorption filtration was needed to narrow the spectra at the expense of a large reduction in x-ray flux. Therefore, potential improvements using a chromatic multi-prism x-ray lens (MPL) for filtering were evaluated theoretically. The MPL offers a narrow tunable spectrum, and we show that the image quality can be improved compared to conventional filtering methods.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Gustafsson, Henrik, et al.
(författare)
-
Prevalence of burnout in competitive adolescent athletes
- 2007
-
Ingår i: The Sport psychologist. - : Human Kinetics. - 0888-4781 .- 1543-2793. ; 21:1, s. 21-37
-
Tidskriftsartikel (refereegranskat)abstract
- This study examined the factorial validity of the Eades Burnout Inventory (EABI) and the prevalence of burnout in adolescent elite athletes and whether burnout is more common in individual sports than in team sports. The EABI was distributed to 980 athletes (402 females and 578 males) in 29 different sports. Confirmatory-factor analyses revealed an acceptable factorial validity for a theoretically supported four-factor model of the EABI. Between 1% and 9% of the athletes displayed elevated burnout scores on these four subscales. The hypothesis of higher prevalence of burnout in individual sports was, however, not supported. Furthermore, no correlation between training load and burnout scores was found. These findings suggest that factors other than training load must be considered when athletes at risk for burnout are investigated.
|
|
| 6. |
- Gustafsson, Henrik, et al.
(författare)
-
The process of burnout : A multiple case study of three elite endurance athletes
- 2007
-
Ingår i: International Journal of Sport Psychology. - : Edizioni Luigi Pozzi srl. - 0047-0767. ; 38:4, s. 388-416
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to gain a better understanding of the process of burning out in endurance athletes. The experiences of three elite cross-country skiers who left Their sport due to burnout were explored. Semi-structured interviews were conducted and inductively analyzed. The Athlete Burnout Questionnaire and training logs were used to validate the interviews and to enrich the analysis. The burnout process was found to evolve with different severity and time perspectives in the three cases. Athletic identity and achievement strivings to validate self-esteem were found to be important driving forces in the burnout process. Also, chronic lack of mental and physical recovery as well as early skiing success leading to high expectations comprised common themes in the burnout process.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
