Results 1 - 10 of 6653
Results 1 - 10 of 6653. Search took: 0.029 seconds
|Sort by: date | relevance|
[en] Purpose: To study the gains from real-time tracking of prostate motion and threshold-based intervention and the feasibility of margin reduction for external beam radiation therapy of prostate cancer. Methods and Materials: Prostate intrafractional motion data from 775 randomly selected treatment fractions (105 prostate patients) were analyzed. Statistical distributions of prostate intrafractional displacement from baseline were used for treatment margin calculation together with other geometrical uncertainties for all patients and a subset of 7 patient who exhibited the largest intrafractional motion. Compared with treatment without any intrafractional intervention, potential reductions in treatment margins were evaluated for treatments with 5-mm and 3-mm threshold-based intervention and four-dimensional (4D) treatments with and without prostate rotation correction. Results: The percentage of time of prostate displacement from the baseline by 3 mm and 5 mm in any direction was 13.4% and 1.8%, respectively, for the general patient population. The ratios were 41% and 15% for the 7 selected patients. Reductions in the posterior margin were 0.2, 0.5, 1.3, and 3.1 mm from the original 7.7 mm, respectively, for 5-mm and 3-mm threshold-based treatments and 4D treatments with and without prostate rotation correction for all patients. They were 1.3, 1.9, 3.1 and 4.9 mm from the original 9.5 mm, corresponding to the 7 selected patients. The treatment margin reductions in other directions were even smaller. Conclusions: Real-time motion tracking and threshold-based intrafractional intervention may play a significant roll in treatment margin reduction for a small fraction of patients but not for the general patient population. Four-dimensional treatments with prostate rotation correction can reduce the treatment margin more significantly.
[en] A special programming system for the KRS 4200 minicomputer with CAMAC periphery is described. The programming language BASIC has been extended by some types of variables, special statements for CAMAC control commands, CAMAC read/write statements, interrupt handling and bit manipulation. Comfortable programming aids for editing running, debugging, file management allow to work out application programs for nuclear physics experiments. (author)
[en] Motion estimation search occupies most time of H.264 encode, Full Integer Motion Search is adopted by motion estimation search in encode model. But the asthmatic quantity of Full Integer Motion Search is too large, and could not be applied in some real time system. Fast Integer Motion Search suitable for H.264 is realized in this paper. This algorithm utilizes different motion characteristics of different images, adopts different search algorithms according as images with different motion characteristic separately. The test results show that this algorithm reduces 84.92% of motion estimation time when the Signal-to-Noise decrease less than 0.1%
[en] Diffusion magnetic resonance imaging (dMRI) has become an established research tool for the investigation of tissue structure and orientation. In this paper, we present a method for real-time processing of diffusion tensor and Q-ball imaging. The basic idea is to use Kalman filtering framework to fit either the linear tensor or Q-ball model. Because the Kalman filter is designed to be an incremental algorithm, it naturally enables updating the model estimate after the acquisition of any new diffusion-weighted volume. Processing diffusion models and maps during ongoing scans provides a new useful tool for clinicians, especially when it is not possible to predict how long a subject may remain still in the magnet. First, we introduce the general linear models corresponding to the two diffusion tensor and analytical Q-ball models of interest. Then, we present the Kalman filtering framework and we focus on the optimization of the diffusion orientation sets in order to speed up the convergence of the online processing. Last, we give some results on a healthy volunteer for the online tensor and the Q-ball model, and we make some comparisons with the conventional offline techniques used in the literature. We could achieve full real-time for diffusion tensor imaging and deferred time for Q-ball imaging, using a single workstation. (authors)
[en] Nematic liquid crystals can be electrically addressed when sandwiched in thin layers. In this paper a liquid crystal optical data composer which is X-Y addressed using the electro-optical effect of index modulation, a field effect, realised for an a.c. electric field on an Homeotropic structure is presented. It is a 128x128 dots display capable of presenting at the same time 1.6x104 digital optical data, with overall writing times of a few milliseconds
[fr]Les cristaux liquides nematiques peuvent etre adresses electriquement lorsqu'ils sont montes en couches minces. On presente dans cette communication un composeur de donnees optiques a cristaux liquides a adressage matriciel, mettant en oeuvre l'effet electro-optique de modulation d'indice, ou effet de champ, obtenu dans une structure homeotrope soumise a un champ electrique alternatif. Il s'agit d'un dispositif d'affichage de 128x128 points capable de presenter simultanement 1,6x104 informations optiques digitales, l'ensemble etant inscrit en quelques millisecondes
[en] The latest video coding standard, H.264/AVC uses in-loop deblocking filter for suppression of blocking artifacts at low bit rates. The deblocking filter can effectively suppress the blocking artifacts due to low bit rate video coding, however it is highly computationally complex. This paper describes statistical analysis of H.264/AVC deblocking filter for various QCIF sequences. The deblocking filtering phenomenon can be divided into two steps: decision to apply filter (no filter/strong filter/normal filter) and application of filter. Number of operations: additions, shifts and comparisons spent in deblocking filter are measured. Moreover, frequency of usage of strong and normal filter for various video sequences is computed. It has been found that 88.49% of average number of operations is spent to take decision about type of filter (no filter/normal filter/strong filter) whereas 11.51% of average number of operations is spent for filtering of samples for various QCIF video sequences. (author)
[en] Beside on-line processing of multiparameter events, two Varian 620 computers have been extensively used for integrated data handling. Records of kinematics and monitoring parameters are transmitted with each spectrum for off-line analysis. An assembly system DAS for Varian 620 has been written in Fortran IV. The 10020 real batch monitor has been transformed in a real time sharing monitor
[fr]Outre le traitement en ligne des evenements multiparametriques, deux unites Varian 620 ont ete utilisees de facon extensive pour le traitement des donnees enregistrees. Les enregistrements des parametres cinematiques et de controle sont transmis avec chaque spectre pour l'analyse hors ligne. Un systeme assembleur DAS, pour Varian 620 a ete ecrit en Fortan IV. Le moniteur CII 10020 ''temps reel par train'' a ete transforme en moniteur ''temps reel partage''
[en] An overview of development trends in man-machine-communication is given. Themes such as real-time databases, vocal in- and outputs, integrated information systems and artificial intelligence are treated