| 21. |
|
|
| 22. |
- Gyllensvärd, Frida, 1980-
(författare)
-
Efficient Methods for Volumetric Illumination
- 2011
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Modern imaging modalities can generate three-dimensional datasets with a very high detail level. To transfer all the information to the user in an efficient way there is a need for three-dimensional visualization. In order to enhance the diagnostic capabilities the utilized methods must supply the user with fast renderings that are easy to interpret correctly.It can thus be a challenge to visualize a three-dimensional dataset in a way that allows the user to perceive depth and shapes. A number of stereoscopic solutions are available on the market but it is in many situations more practical and less expensive to use ordinary two-dimensional displays. Incorporation of advanced illumination can, however, improve the perception of depth in a rendering of a volume. Cast shadows provide the user with clues of distances and object hierarchy. Simulating realistic light conditions is, however, complex and it can be difficult to reach interactive frame rates. Approximations and clever implementations are consequently required.This thesis presents efficient methods for calculation of illumination with the objective of providing the user with high spatial and shape perception. Two main types of light conditions, a single point light source and omni-directional illumination, are considered. Global transport of light is efficiently estimated using local piecewise integration which allows a graceful speed up compared to brute force techniques. Ambient light conditions are calculated by integrating the incident light along rays within a local neighborhood around each point in the volume.Furthermore, an approach that allows the user to highlight different tissues, using luminous materials, is also available in this thesis. A multiresolution data structure is employed in all the presented methods in order to support evaluation of illumination for large scale data at interactive frame rates.
|
|
| 23. |
- He, Xinkui, et al.
(författare)
-
Interference effects in two-color high-order harmonic generation
- 2010
-
Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 82:3
-
Tidskriftsartikel (refereegranskat)abstract
- We study high-order harmonic generation in argon driven by an intense 800 nm laser field and a small fraction of its second harmonic. The intensity and divergence of the emitted even and odd harmonics are strongly modulated as a function of the relative delay between the two fields. We provide a detailed analysis of the underlying interference effects. The interference changes drastically when approaching the cutoff region due to a switch of the dominant trajectory responsible for harmonic generation.
|
|
| 24. |
|
|
| 25. |
- Jackowski, Christian, 1975-, et al.
(författare)
-
Magnetic resonance imaging goes postmortem: noninvasive detection and assessment of myocardial infarction by postmortem MRI
- 2011
-
Ingår i: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; Jan;21:1, s. 70-78
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To investigate the performance of postmortem magnetic resonance imaging (pmMRI) in identification and characterization of lethal myocardial infarction in a non-invasive manner on human corpses.MATERIALS AND METHODS: Before forensic autopsy, 20 human forensic corpses were examined on a 1.5-T system for the presence of myocardial infarction. Short axis, transversal and longitudinal long axis images (T1-weighted; T2-weighted; PD-weighted) were acquired in situ. In subsequent autopsy, the section technique was adapted to short axis images. Histological investigations were conducted to confirm autopsy and/or radiological diagnoses.RESULTS: Nineteen myocardial lesions were detected and age staged with pmMRI, of which 13 were histologically confirmed (chronic, subacute and acute). Six lesions interpreted as peracute by pmMRI showed no macroscopic or histological finding. Five of the six peracute lesions correlated well to coronary pathology, and one case displayed a severe hypertrophic alteration.CONCLUSION: pmMRI reliably demonstrates chronic, subacute and acute myocardial infarction in situ. In peracute cases pmMRI may display ischemic lesions undetectable at autopsy and routine histology. pmMRI has the potential to substantiate autopsy and to counteract the loss of reliable information on causes of death due to the recent disappearance of the clinical autopsy.
|
|
| 26. |
- Jackowski, Christian, 1975-, et al.
(författare)
-
Quantitative MRI in Isotropic Spatial Resolution for Forensic Soft Tissue Documentation. Why and How?
- 2011
-
Ingår i: Journal of Forensic Sciences. - : Blackwell. - 0022-1198 .- 1556-4029. ; 56:1, s. 208-215
-
Tidskriftsartikel (refereegranskat)abstract
- A quantification of T1, T2, and PD in high isotropic resolution was performed on corpses. Isotropic and quantified postmortem magnetic resonance (IQpmMR) enables sophisticated 3D postprocessing, such as reformatting and volume rendering. The body tissues can be characterized by the combination of these three values. The values of T1, T2, and PD were given as coordinates in a T1-T2-PD space where similar tissue voxels formed clusters. Implementing in a volume rendering software enabled color encoding of specific tissues and pathologies in 3D models of the corpse similar to computed tomography, but with distinctively more powerful soft tissue discrimination. From IQpmMR data, any image plane at any contrast weighting may be calculated or 3D color-encoded volume rendering may be carried out. The introduced approach will enable future computer-aided diagnosis that, e.g., checks corpses for a hemorrhage distribution based on the knowledge of its T1-T2-PD vector behavior in a high spatial resolution.
|
|
| 27. |
- Jönsson, Lars-Eric, et al.
(författare)
-
Institution
- 2011
-
Bok (övrigt vetenskapligt/konstnärligt)abstract
- Institution ger 250 miljoner träffar på sökmotorn Google. I vilka sammanhang används detta slitstarka ord och vilka betydelser bär det på? I den här boken undersöks institutioner som platser, rum och organisationer samt begreppets vetenskapliga utveckling och användning. Institutioner representerar ofta socialt tvång, beständighet över tid och reglering av aktörers handlande.
|
|
| 28. |
|
|
| 29. |
|
|
| 30. |
- Kalra, Mannudeep, et al.
(författare)
-
Iterative Reconstruction Techniques: The Be-All and End-All for CT Dose Reduction? Pictorial Synopsis of Different Vendor Techniques
- 2010
-
Ingår i: In Proceedings of RSNA 2010, LL-PHE 4076.
-
Konferensbidrag (refereegranskat)abstract
- Recently introduced IRT for clinical use allow dose reduction for adult and pediatric CT while maintaining or even enhancing image quality compared to filtered back projection based reconstruction. Specific adjustments of scanning protocols and fine-tuning of iterative settings are necessary to ensure optimum usage with understanding of its potential and disadvantages. This educational exhibit focuses on clinical illustrations to simplify application of IRT for reducing CT radiation dose
|
|
