| 1. |
- Angelopoulos, Angelos, et al.
(författare)
-
Dispersion relation analysis of the neutral kaon regeneration amplitude in carbon
- 1999
-
Ingår i: European Physical Journal C. - : Springer Berlin/Heidelberg. - 1434-6044 .- 1434-6052. ; 10:1, s. 19-25
-
Tidskriftsartikel (refereegranskat)abstract
- We apply a forward dispersion relation to the regeneration amplitude for kaon scattering on 12" style="position: relative;" tabindex="0" id="MathJax-Element-1-Frame" class="MathJax">12C using all available data. The CPLEAR data at low energies allow the determination of the net contribution from the subthreshold region which turns out to be much smaller than earlier evaluations, solving a long standing puzzle.
|
|
| 2. |
- Angelopoulos, A., et al.
(författare)
-
K 0–KÌ„0 mass and decay-width differences : CPLEAR evaluation
- 1999
-
Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 471:2, s. 332-338
-
Tidskriftsartikel (refereegranskat)abstract
- The CPT-violation parameters Re(δ) and Im(δ) determined recently by CPLEAR are used to evaluate the K0– mass and decay-width differences, as given by the difference between the diagonal elements of the neutral-kaon mixing matrix (M−iΓ/2). The results – GeV and GeV – are consistent with CPT invariance. The CPT invariance is also shown to hold within a few times 10−3–10−4 for many of the amplitudes describing neutral-kaon decays to different final states.
|
|
| 3. |
- Cahn, R N, et al.
(författare)
-
Detective quantum efficiency dependence on x-ray energy weighting in mammography
- 1999
-
Ingår i: Medical physics. - Medical physics : Wiley. - 0094-2405. ; 26:12, s. 2680-2683
-
Tidskriftsartikel (refereegranskat)abstract
- An evaluation of the dependence of detective quantum efficiency (DQE) on the incident energy spectrum has been made for mammography. The DQE dependence on the energy spectrum has been evaluated for energy-integrating detectors, photon-counting detectors, and detectors that measure the energy of each photon. To isolate the effect of the x-ray energy spectrum the detector has been assumed to be ideal, i.e., all noise sources are assumed to be zero except for quantum fluctuations. The result shows that the improvement in DQE, if the energy-integrating detector is compared to a single-photon counting detector, is of the order of 10%. Comparing the energy-integrating detector and the detector measuring the energy for each photon the improvement is around 30% using a molybdenumanodespectrum typical in mammography. It is shown that the optimal weight factors to combine the data in the case the energy is measured are very well approximated if the weight factors are proportional to E−3." style="position: relative;" tabindex="0" id="MathJax-Element-1-Frame" class="MathJax">E−3. Another conclusion is that in calculating the DQE, a detector should be compared to one that uses ideal energy weighting for each photon since this provides the best signal-to-noise ratio. This has generally been neglected in the literature.
|
|
| 4. |
- Caidahl, Kenneth, 1949, et al.
(författare)
-
New concept in echocardiography: harmonic imaging of tissue without use of contrast agent.
- 1998
-
Ingår i: Lancet (London, England). - : Elsevier BV. - 0140-6736. ; 352:9136, s. 1264-70
-
Tidskriftsartikel (refereegranskat)abstract
- Endocardial border detection is important for echocardiographic assessment of left-ventricular function. Second harmonic imaging of contrast agents enhances this border detection. We discovered that harmonic imaging improves tissue visualisation even before contrast injection. We therefore sought objectively to demonstrate the degree of enhancement of endocardial and myocardial visualisation.An ATL HDI-3000 scanner with software for contrast harmonic imaging was used to record short-axis images of the left ventricle in 27 patients with possible myocardial disease and 22 controls, in the fundamental mode and with harmonic imaging. A computer program measured the relative grey-scale values within six segments of the endocardium and myocardium. An Acuson Sequoia scanner equipped with software for tissue harmonic imaging was used to investigate the reproducibility of ejection-fraction calculations in 22 patients with ischaemic heart disease.Harmonic imaging produced brighter endocardium within each segment. Relative to the mean grey value of the total imaging sector, the values for harmonic and fundamental imaging were 171.5 vs 85.6% (p<0.0001) in end diastole and 194.1 vs 106.7% (p<0.0001) in end systole. Results for the myocardial segments were also significantly better for harmonic imaging. Structure enhancement of similar magnitude was seen among patients and healthy controls. Use of harmonic imaging reduced the proportion of unacceptable images by 14-46% in different views and improved the reproducibility of biplane ejection-fraction measurements.In comparison with fundamental imaging, the relative endocardial and myocardial brightness is enhanced by harmonic imaging.
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Frimmel, Hans
(författare)
-
Biopsy Needle Optimisation
- 1997
-
Ingår i: Proc. 10th Scandinavian Conference on Image Analysis. - : Pattern Recognition Society of Finland. - 9517641451 ; , s. 381-387
-
Konferensbidrag (refereegranskat)
|
|
| 9. |
|
|
| 10. |
- Frimmel, Hans, 1968-
(författare)
-
Positioning Biopsy Needles in the Prostate Gland Using 3D Computer Modelling
- 1999
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the world of medicine, image diagnostics have, until recently, been based merely on two dimensional information sources. The understanding of three dimensional structures has been limited to creating mental images in the mind of the physician, to wax models and to autopsy. In the last few years, computers have made it possible to model and reconstruct real three dimensional objects and thus give the physician a new tool not only to describe localisation and distribution patterns of diseases, above all cancer, but also as an aid in the understanding of the human body. This thesis contributes in the development of such tools, based on a specific application.Prostate cancer is for men the most common form of cancer. Improvement in diagnostics for this form of cancer would facilitate planning of treatment and hence save, and preserve the quality of, life. One way to diagnose and quantify prostate cancer is to assess its presence and malignancy grade in cylindrical tissue samples taken with a needle biopsy device. Today, two to six such samples are generally taken, with poorly standardised rules for the positioning of the needle, thus interindividual variation exists.In this thesis, 3D models to analyse the problem with the positioning of biopsy needles have been developed. By using information from physical prostates removed from patients by surgery, a 3D cancer probability distribution has been built. Using this information, a standardised biopsy needle protocol has been created that is efficient, stable and easy to use. In this process new methods for morphing images, registrating slices and optimising positions for use with computer modelling have been developed.Many physicians were involved in the study. Thus, an important part of the work has been to make every part of the work understandable for people without special computer programming knowledge. Also, efforts have been made to make it possible to easily examine every piece of information created in order to verify the correctness of the methods used.
|
|
