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[en] The present invention utilizes holes which are an integer times smaller in each direction than holes in conventional ura patterns. A balance correlation function is generated where holes are represented by 1's, nonholes are represented by -1's, and supporting area is represented by 0's. The self-supporting array can be used for low energy applications where substrates would greatly reduce throughput. The balance correlation response function for the self-supporting array pattern provides an accurate representation of the source of nonfocusable radiation
[en] A variety of algorithms have been coded to allow the user to analyze or transform an image by selecting one or more processes from a list. In this way a set of processing techniques can be used which are appropriate for a specific image. A number of such processing techniques are discussed. 4 refs.; 10 figs
[en] In this system the subject under observation is subjected to a radioactive label under the effect of which each of its points emits a radiation picked up by the scintiscanner, to which four electric signals are made to correpond by the scintiscanner and as from which the signal of the corresponding image point is worked out, to determine the intensity of the radiation of the point and to compare it against a mean level, preset for a given label, in an energy window of a given width around this level, characterized in that it includes means for ensuring, for each point, the selection of the greatest of the four signals of this point and injecting it in this window
[fr]Dans ce systeme le sujet a observer est soumis a l'action d'un marqueur radioactif sous l'effet duquel chacun de ses points emet un rayonnement capte par la chaine, qui lui fait correspondre quatre signaux electriques a partir desquels est elabore le signal du point de l'image correspondant pour determiner l'intensite du rayonnement du point, et de la comparer avec un niveau moyen, fixe a l'avance pour un marqueur determine, dans une fenetre d'energie d'une largeur determinee autour de ce niveau, caracterise en ce qu'il comprend des moyens assurant, pour chaque point, le prelevement du plus grand des quatre signaux de ce point et l'injectant dans ladite fenetre
[en] In transversal computer tomography apparatus, in which the positioning zone in which the patient can be positioned is larger than the scanning zone in which a body slice can be scanned, reconstruction errors are liable to occur. These errors are caused by incomplete irradiation of the body during examination. They become manifest not only as an incorrect image of the area not irradiated, but also have an adverse effect on the image of the other, completely irradiated areas. The invention enables reduction of these errors
[en] An implementation of two new automatized image processing algorithms for contrast enhancement of portal images is presented as suitable tools which facilitate the setup verification and visualization of patients during radiotherapy treatments. In the first algorithm, called Automatic Segmentation and Histogram Stretching (ASHS), the portal image is automatically segmented in two sub-images delimited by the conformed treatment beam: one image consisting of the imaged patient obtained directly from the radiation treatment field, and the second one is composed of the imaged patient outside it. By segmenting the original image, a histogram stretching can be independently performed and improved in both regions. The second algorithm involves a two-step process. In the first step, a Normalization to Local Mean (NLM), an inverse restoration filter is applied by dividing pixel by pixel a portal image by its blurred version. In the second step, named Lineally Combined Local Histogram Equalization (LCLHE), the contrast of the original image is strongly improved by a Local Contrast Enhancement (LCE) algorithm, revealing the anatomical structures of patients. The output image is lineally combined with a portal image of the patient. Finally the output images of the previous algorithms (NLM and LCLHE) are lineally combined, once again, in order to obtain a contrast enhanced image. These two algorithms have been tested on several portal images with great results. - Highlights: • Two Algorithms are implemented to improve the contrast of Electronic Portal Images. • The multi-leaf and conformed beam are automatically segmented into Portal Images. • Hidden anatomical and bony structures in portal images are revealed. • The task related to the patient setup verification is facilitated by the contrast enhancement then achieved.
[en] The analogical tomographic method, presented in this paper, is essentially based on the principle of a 'transaxial' geometry. An optical technique for coding information, allows data to be preprocessed and then processed both analogically. This method may be performed in real time and may be applied to various sorts of radiations, in 'transmission tomography' as in 'emission tomography', if we can represent mathematically the input data by the so-called 'projections' of a parameter which characterizes the 3-D object to be reconstructed
[fr]La methode analogique de tomographie, presentee ici, est essentiellement basee sur le principe de l'utilisation d'une geometrie 'axiale transverse'. Une technique de codage optique de l'information permet d'effectuer analogiquement le pretraitement des donnees et le traitement proprement dit. Il est possible de mettre en oeuvre la methode en temps reel et de l'appliquer a divers types de rayonnements aussi bien en tomographie par transmission qu'en tomographie par emission, dans la mesure ou les donnees de depart sont representables mathematiquement par des 'projections' du parametre caracteristique de l'objet tridimensionnel a reconstruire
[en] In order to overcome classical wavelets' shortcoming in image processing problems, people developed many producing systems, which built up wavelet family. In this paper, the notion of AB-multiresolution analysis is generalized, and the corresponding theory is developed. For an AB-multiresolution analysis associated with any expanding matrices, we deduce that there exists a singe scaling function in its reducing subspace. Under some conditions, wavelets with composite dilations can be gotten by AB-multiresolution analysis, which permits the existence of fast implementation algorithm. Then, we provide an approach to design the wavelets with composite dilations by classic wavelets. Our way consists of separable and partly nonseparable cases. In each section, we construct all kinds of examples with nice properties to prove our theory.