DEVICE FOR THE INVESTIGATION OF THE DYNAMIC BEHAVIOR OF A SCANSYSTEMS

The invention concerns a device for the investigation of the dynamic behavior of a Scansystems with the application of the computer tomography. In the radiological diagnostics, thus also with the application of the computer tomography, for the better Sichtbarmachung of the blood vessels and the different strong blood circulation S by human fabrics contrast means are intravenously injected. By injecting the Konstrastmittels at least the radiographic density changes during the Scanvorganges by the penetration of the contrast means in subsections of the layer which can be illustrated. Task of the invention is it to simulate by a device this procedure artificially in order to become acquainted with the behavior of the algorithm of the computer contained in the computer tomography plant with the production of the picture of the scanned layer. The initially quoted device according to invention is characterized by it that a phantom is intended, its radiographic density toward the longitudinal axis continuously or gradually zu-bzw, decreases and that this phantom is during a Scanvorganges perpendicularly to the Scanebene toward the longitudinal axis movable and the phantom from a preferably cylindric container, which exhibits several separated chambers, whereby the partitions are arranged perpendicularly to the cylinder axle and that these individual chambers are filled with a liquid, whereby each liquid each chamber defined radiographic density exhibits. With the invention it is to be simulated for the first time possible the change of the radiographic density by the penetration of the contrast means in the human fabric and be seized regarding the picture position by a Computertomographen. With phantom according to invention a change of the radiographic density is to be produced by 30 to 60 Hounsfield units HE within a time from 3 to 30 s. Phantom according to invention is induced to it toward its longitudinal axis during a Scanvorganges. There the production phantoms with a continuous Abbzw. Increase of the radiographic density is extremely complex, becomes a phantom in accordance with above remarks with a gradual Abbzw. Increase of the radiographic density suggested. The individual chambers are filled with a liquid, whereby the first chamber exhibits a liquid with 30 HE and the further chambers possesses a liquid rising with 2,5 HE, so that in the last chamber a liquid with approximately 60 HE is. In accordance with a substantial characteristic of the invention that exhibits phantom the form of a cylindrical body, whereby the cross section in a circle, elliptically, nierenförmig od.dgl, is. The production the phantoms with circular cross section is surely the simplest way. The algorithm is to be above all also examined however, if the radiographic density in a not-circular cross section changes temporally. Favourable way could be simply elliptical this cross section nierenförmig, or. Other cross-sectional shapes are not to be excluded. In accordance with a special arrangement of the invention that consists phantom of the base material polyester resin, whereby accelerators and/or hardeners and/or fillers are mixed to this base material such as chalk, Eccospheres and/or salt. This material has the advantage that its radiographic density corresponds to the density of the human fabric. The radiographic density is changed by the addition of accelerator, hardener and fillers according to the demands, which the medicine makes, slightly. The different radiographic density can be obtained over the procedure of the internal separation of the fillers, whereby an influence of the separation takes place via extension of the hardening times and/or via increase of the ambient temperature. This procedure of the internal separation of the fillers favourable-proves used to obtain in out these materials perpendicularly poured rod-shaped body a from top to bottom linear rising radiographic density. In accordance with a further characteristic of the invention that is embedded phantom in a cylinder, which is filled with water. Since also the effect of the imbedding of the cross section changing in the radiographic density is in the fabric or water from interest, is this arrangement of advantage. In accordance with a special arrangement of the invention that consists phantom of plexiglass. This material appropriately presents itself because of its small radiographic density (about 100 HE) as material. After a further favourable arrangement of the invention the liquid is a mixture from water and a common Roentgen contrast means. The liquid with the exactly defined radiographic density, fill inable into the chambers, is a mixture of water and the common contrast means Urovist. Each chamber can exhibit two diametrically facing lockable openings. Thus changing is made possible for the liquid. It turned out that with longer whereabouts the radiographic density changes to the liquid in the chambers can be subject. One will appropriately keep these openings as small as possible, so that they do not go at the computer picture disturbing into action. In accordance with a further characteristic of the invention that is accommodated phantom for movement in axial direction in a plexiglass pipe of larger diameter and over roles as well as one at the cover plate fastened driving device movably. Thus a perfect movement the phantoms is ensured. A further arrangement of the invention is to be seen in it that a disk-shaped body with a certain radiographic density is firmly in the Scanebene intended, in the center an opening exhibits, by which the phantom is movable. This disk-shaped body must exhibit a height, which is larger or at least alike to the layer thickness which can be examined and a cross section have, which depends on the question which can be examined. Now the phantom with lengthwise-variable radiographic density can be pushed by the opening. In accordance with an advancement of the invention for the prevention of an air gap between the surface a substance is intended the phantoms and the inner surface of the opening. There an air gap to artifacts in the picture reconstruction to lead can is this measure of advantage. On the basis a remark example represented in the designs the invention is more near described. Fig.1 shows a phantom filled with liquid and Fig.2 a one with continuous lengthwise-variable radiographic density. In accordance with the designs that is phantom --1-- as cylindrical container trained, that in thirteen from each other separated chambers --2a, 2b,…. -- is subdivided. The individual partitions --3-- are arranged perpendicular to the cylinder axle and consist only of thin plastic foils. The chamber --2a-- the chamber is filled with a liquid, whose radiographic density amounts to 30 HE, --2b-- with a liquid of 32,5 HE etc. according to the partitioning the phantoms in thirteen chambers --2a, 2b,…. -- a liquid with 60 HE results for the last chamber. as to filling and/or for emptying each chamber --2-- these two diametrically facing point lockable openings with rubber seals and plastic plugs --4-- up. To the movement the phantoms --1-- in axial direction this becomes in a plexiglass pipe --5--, which exhibits a larger diameter, accommodated and over roller bearings --6-- moved. At the cover plate --7-- the phantoms --1-- becomes a flange of a spindle --8-- rigidly fastens. This spindle --8-- becomes by one in an end plate --9-- the external pipe --5-- swivelling stored mother --10-- led. On this mother --10-- is a gear wheel --11-- pressed on, into the one second gear wheel --12-- intervenes, which on the axle of the laterally shifted engine --13-- sits. As engine --13-- a stepping motor use finds, over a gate circuit the mother to that --10-- to rotate and thus the spindle lets --8-- and to it fastened phantom --1-- dependent on the direction of rotation in or other direction moves. For this application a stepping motor is used, because it does not require regulation on the one hand by the defined switching steps and on the other hand for the rapid deceleration the phantoms --1-- necessary large retaining moment exhibits. For the determination of the necessary contrast central concentration it is still implemented that 100 proportions each water are mixed with 0,1 and 2 proportions contrast means and the radiographic density are measured. With these three received measured values a linear function is calculated and determined with this function the proportions contrast means for the defined radiographic density. A further important point is the fact that liquid Phantome of problems in the mechanical stability, in which temporal Konstanz of the radiographic density, in which, with transport as well as by the large moved mass with itself brings handling. For modern Computertomographen it in certain cases, a cylindrical staff with given is sufficient röntgenographiS schen for density longitudinal section by the Scanebene to move. With older plants the Scanzeiten is long according to in addition, so that very often only model tests with changed Zeitmaßstab are meaningful. The effect of the imbedding of the Quersehnittes changing in the radiographic density is in addition, in principle in the fabric or water of interest. In this case that must be moved phantom in a water cylinder by the Scanebene, whereby again high moving masses and the problem of the handling from filled with liquid phantom in weakened form would remain to develop. In accordance with Fig.2 a further development is represented, whereby a disk-shaped body --14-- firmly in the Scanebene of the Computertomographen is positioned. By the opening --14-- is now the phantom becomes --1-- with lengthwise-variable radiographic density pushed. Both the firmly positioned disk-shaped body --14-- could be filled with a liquid, and moved phantom --1-- can consist of liquid chambers. It, the body is appropriate --14-- to implement as solids with suitable radiographic density and compose moved phantom either of firm layers with different radiographic density or to use still better a cylinder with continuous (e.g. linear) longitudinal process of the radiographic density. A problem, which can occur during this execution, is that between firm and moved cylinder inevitably an air gap exists, which can change despite exact storage and guidance also temporally. This air gap can lead to artifacts in the picture reconstruction. It offers from there the additional use of a “lubrication substance” the possibility of controlling this problem. The temporal change of the density increase can be simulated with consideration of the longitudinal dependence of the radiographic density of the moved cylinder for example by suitable programming of the drive.