Abstract: The invention relates to a method for producing computer tomography images from limited data of a region of interest of an image object which can be subject to changes, comprising the steps of a) producing a first computer tomography image of the region of interest (source image) by acquiring a sufficient set of projection data and using a standard CT-image reconstruction technique, b) selecting at least one transformation function depending on expected changes of the image object, c) acquiring CT-data of the image object from a limited number of projections under a limited range of observation angles, d) reconstructing a new image of the region of interest (target image) by an iterative procedure starting from the source image of the region of interest, deforming the source image by using the transformation function and optimizing the target image in view of the acquired CT-data from the limited number of projections.

Abstract: A backprojection unit is described that is adapted for back-projecting pixel data of n acquired projections onto a voxel subvolume, with n being a natural number. For each of the n projections, the backprojection unit comprises voxel center determination means adapted for projecting m contiguous voxels onto a respective one of the projections, with m 2 being a natural number, memory access means adapted for fetching, for each of the m projected voxel centers, pixel data of pixels adjacent to the projected voxel center from a respective projection buffer, and multiplexing means adapted for distributing the fetched pixel data to m different pipelines. Furthermore, a method for backprojecting pixel data of n acquired projections onto a voxel subvolume is disclosed.

Abstract: The invention relates to a method for producing computer tomography images from limited data of a region of interest of an image object which can be subject to changes, comprising the steps of a) producing a first computer tomography image of the region of interest (source image) by acquiring a sufficient set of projection data and using a standard CT-image reconstruction technique, b) selecting at least one transformation function depending on expected changes of the image object, c) acquiring CT-data of the image object from a limited number of projections under a limited range of observation angles, d) reconstructing a new image of the region of interest (target image) by an iterative procedure starting from the source image of the region of interest, deforming the source image by using the transformation function and optimizing the target image in view of the acquired CT-data from the limited number of projections.

Abstract: A method of intensity-modulating a beam of radiation from a radiation source is provided, the method including the steps of: a) providing a collimator having a window which allows the passage of radiation from the radiation source and which defines when viewed from the radiation source a two-dimensional array of bixels, the collimator further having a plurality of independently movable radiation attenuators which are constrained to move along columns or rows of the array to block selected bixels thereof, whereby, within each column or row along which the attenuators are movable, at least one arrangement of the respective attenuator(s) results in a pair of open bixels sandwiching a blocked bixel or line of blocked bixels; b) positioning the collimator in the path of the radiation source; and c) repeatedly: positioning the radiation attenuators within the window to form at each repeat a different pattern of bixels; and irradiating the collimator, until a predetermined pattern of radiation intensities for the be

Abstract: The invention relates to a collimator (1) for defining a beam of energetic rays (2) which is emitted from an essentially punctiform radiation source (3) and is oriented onto an object (1) to be treated. The collimator is especially used for the stereotactic conformation radiotherapy of tumors. The collimator (1) is embodied in such a way that an irregular object (4) can be scanned by rays (2, 2?) which are defined by an opening in the collimator. The invention also relates to a program for controlling the collimator. In order to define the contours (29, 29?, 29?) of the objects (4) to be irradiated in a simple but highly accurate manner, especially with a precise definition of the irradiation fields, the collimator comprises a plurality of different sized openings (5, 5? 5?). One of the openings (5, 5?, 5?) can be selectively displaced in a polydirectional manner on a strip (6) having a spherical surface, and the central axis (7) thereof is oriented towards the radiation source (3).

Abstract: The invention relates to a method and a device for reconstructing an image in a spatial volume on the basis of acquired projections, wherein during a reconstruction step each acquired projection or each region of an acquired projection is fed once into a data processing system from a memory for the acquired projections and intensity of a voxel of the reconstructed spatial volume image is updated during the reconstruction step for each voxel relevant projection or region.

Abstract: The invention relates to a collimator (1) for defining a beam of energetic rays (2) which is emitted from an essentially punctiform radiation source (3) and is oriented onto an object (1) to be treated. The collimator is especially used for the stereotactic conformation radiotherapy of tumors. The collimator (1) is embodied in such a way that an irregular object (4) can be scanned by rays (2, 2?) which are defined by an opening in the collimator. The invention also relates to a program for controlling the collimator. In order to define the contours (29, 29?, 29?) of the objects (4) to be irradiated in a simple but highly accurate manner, especially with a precise definition of the irradiation fields, the collimator comprises a plurality of different sized openings (5, 5? 5?). One of the openings (5, 5?, 5?) can be selectively displaced in a polydirectional manner on a strip (6) having a spherical surface, and the central axis (7) thereof is oriented towards the radiation source (3).

Abstract: The invention relates to a method and a device for reconstructing an image in a spatial volume on the basis of acquired projections, wherein during a reconstruction step each acquired projection or each region of an acquired projection is fed once into a data processing system from a memory for the acquired projections and the intensity of a voxel of the reconstructed spatial volume image is updated during the reconstruction step for each voxel relevant projection or region.

Abstract: The invention relates to a collimator (1) for limiting a bundle of high-energy rays (2), which is emitted by a substantially point-like radiation source (3) and directed towards a treatment object (20) and used in particular for the stereotactic conformation radiotherapy of tumors. According to the invention the collimator (1) comprises a plurality of diaphragm leaves (4, 4′) which are arranged opposite each other and which are made of a radiation-absorbing material and which, by means of drive mechanisms, can be moved into the optical path in such a way that the contours and/or exposure period of said optical path can be freely defined, the front edges (5, 5′) of the diaphragm leaves (4, 4′) being parallel to the optical path at all times.

Abstract: A contour collimator for radiation therapy has a plurality of diaphragm elements that are movable with respect to each other by means of drive units. The diaphragm elements of the invention are supported only on the side near the drive units for ease of movement. This allows larger contour collimators to be constructed having relatively heavy diaphragm elements while retaining relatively small motors.

Abstract: The invention relates to a displacement-detecting element (1) comprising a measuring resistance (2), voltage source (3) and a displacement-dependent voltage pick off (4). The measuring resistance (2) is embodied in the form of a strip. The length of the resistor (6) corresponds to at least the maximal length of displacement (7) of the component to be detected. The invention also relates to a multileaf collimator (23) having such a displacement-detecting element (1). The aim of the invention is to produce a displacement-detecting element (a) for detecting the position of the leaves (22) in a multileaf collimator (23) in a precise and faultless manner.

Abstract: The invention relates to a displacement-detecting element (1) comprising a measuring resistance (2), voltage source (3) and a displacement-dependent voltage pick off (4). The measuring resistance (2) is embodied in the form of a strip. The length of the resistor (6) corresponds to at least the maximal length of displacement (7) of the component to be detected. The invention also relates to a multileaf collimator (23) having such a displacement-detecting element (1). The aim of the invention is to produce a displacement-detecting element (a) for detecting the position of the leaves (22) in a multileaf collimator (23) in a precise and faultless manner.

Abstract: The invention relates to a medical device having a mechanism (1) for positioning a devise (4) by means of an arm (7), said arm consisting of at least three members (8, 9, 10), wherein the mechanism (1) has at least five adjustment axes (11, 12, 13, 14, 15, 16), fine adjustment and locking devices (17) being assigned thereto. The medical device is configured in such a way that it can be used universally, especially as a device for stereotaxis that can be placed anywhere and that does not interfere with other medical measures and also as a position determining device that can be placed anywhere for determining the position of a patient (29). This is achieved in that the mechanism (1) has a base part (5) that can be fixed in any given location in the region of the patient (29) in such a way that the device (4) can reach all given target points (2) in or on the patient (29) in practically any direction (3).

Abstract: The radiation system has several radiation sources aimed toward a central point. These radiation sources are on arc element that pivots on an axis. The center can hence be irradiated from different sides. The radiation sources preferably have irregularly adjustable diaphragms. The system is suitable for irradiating any part of the human body. It is easy to manufacture and simple to used.

Abstract: A contour collimator has a plurality of plate-shaped diaphragm elements movably arranged with respect to each other in a guiding block to form a contour diaphragm for a radiation beam emitted by a radiation source towards the collimator, and at least one drive for moving the diaphragm elements. A drive is associated with each diaphragm element with the drives of a group of diaphragm elements being substantially adjacent, and a driving transmission arranged between each drive and the associated diaphragm element.

Abstract: A whole body stereotaxis apparatus comprising a base plate (2) to accommoe a patient, two side strips (4, 6) which are attached to the base plate (2) at the marginal or side edges thereof and laterally delimit the base plate (2) and to which arches (10, 12) extending over the base plate (2) can be attached, characterized in that a central strip (8) is mounted on the base plate (2) and comprises bores (22) to accommodate accessories.

Abstract: A circuit for the conversion of an unregulated input voltage (UE) into a regulated DC output voltage (UA) is specified, with which the input voltage (UE) can assume both a higher and a lower value than the desired output voltage (UA). In addition to a set/actual value comparator (SIV), a current simulation (SNB) is provided, which simulates the current (JL) in the storage choke (L2) during charging as capacitor voltage, a common driver circuit (TRS), designed as switched constant current source, for both semiconductor switches (V1, V2), an input voltage monitoring (ESU), which switches off the switched-mode regulator when there is too low an input voltage (UE) and an output monitoring circuit (ASU), which reduces the set value of the regulating circuit on crossing in the downward direction of a selectable threshold.

Abstract: In a free-oscillating converter for the current supply of a monitor, the switching frequency of an electronic switch is positioned midway between two consecutive multiples of the line frequency of the monitor, which obviates the necessity for a technically and financially expensive synchronization between switching frequency and line frequency. In the operating range of the converter, it is sufficient to adhere to the switching frequency with an accuracy of a few hundred Hz (f.sub.s .apprxeq.1.5+x).multidot.f.sub.z, where x.epsilon. .sub.o, f.sub.s =switching frequency and f.sub.z =line frequency.

Abstract: A vertically adjustable carrier for a vise comprises a vertical support tube and a mounting which can be secured to a work bench and which comprises two semicylindrical shells which embrace the support tube and which can be clamped together to fix the support tube in any desired vertical position. The shells extend downwardly from the mounting and define a cavity which accommodates a gas spring which abuts on one end on the support tube and on the other end on the bottom of the composed half shells and exerts an upwardly directed force on the support tube to ease its vertical movement.

Abstract: A vertically adjustable carrier for a vise or the like comprises a vertical support tube which is guided in a clamping device comprising two semicylindrical shells which can be clamped together. The shells are connected on one side by two support elements arranged vertically one below the other, and on the other side there is provided a clamping screw which is arranged between the horizontal planes through the support elements. By such arrangement a great resistance against unintended turning of the support tube even with a relatively slight tightening of the clamping screw is obtained.