Abstract: In one embodiment, the present invention is a method for positioning an x-ray beam on a multi-slice detector array of an imaging system in which the detector array has rows of detector elements and is configured to detect x-rays in slices along a z-axis. The method includes steps of comparing data signals representative of x-ray intensity received from different rows of detector elements and positioning the x-ray beam in accordance with a result of the comparison.

Abstract: An X-ray imaging apparatus has an image intensifier for converting an X-ray shadowgram of a patient into visible light. A primary lens group collimates the visible light and a secondary lens group forms the image carried by the visible light on a TV imaging device. The primary lens group is provided with a beam splitter for reflecting a part of the light output by the image intensifier toward the secondary lens group and transmitting the remainder thereof to a pick-up optical system for detecting the brightness of the image output by the image intensifier. The exposure of the patient to X-rays can be controlled on the basis of the detected brightness.

Abstract: The invention relates to a method of forming images of layers of an object, and a device for performing this method. The layer images are formed from single-shadow images produced from different radiation source positions. The image values of the single-shadow images are first stored in a first as well as in a second memory. From the values of given image points in the second memory, a layer image value is calculated. The layer image value is added to the corresponding image points in a third memory. From the differences between these standardized sums in the third memory and the original image values in the first memory, there are formed correction values for correcting the image values in the second memory. Improved layer images are thus obtained.

Abstract: A doubly-curved crystal for use in a scanning monochromator is oriented with respect to a reference plane containing source and image locations of the monochromator. The crystal has concave planes of lattice points and a concave crystal surface which satisfy Johannson geometric conditions within the reference plane for a Rowland circle of radius R. The planes of lattice points are substantially spherically curved to a radius of 2R, and the crystal surface is substantially toroidally curved with a radius of substantially 2R within a plane perpendicular to the reference plane. The crystal may be formed by plastically deforming a cylindrically curved crystal blank over a doubly-curved convex die.

Abstract: The present invention relates to an arrangement for the non-destructive measurement of metal traces in the surface of material samples in which the surface is irradiated with X-ray radiation and a detector, fastened above the material sample, spectrometrically examines the fluorescent radiation emanating from the material sample. Metal impurities are detected in the surface of, for example, silicon wafers down to about 10.sup.11 atoms/cm.sup.2, on-line, with the wafers being free from contamination by the measuring process. It is possible to sweep the entire surface area of wafers having a diameter up to about 150 mm at the locations fixed by the respective standards. The X-ray radiation directed onto the surface of the material sample by means of an adjustable X-ray source, the divergence of the exciting X-ray radiation being limited by two aperture members, the aperture members being disposed in a quartz body serving as an optical bench.

Abstract: A positioning control system controls the shifting of one of a plurality of radiation filters into the ray path. Transducers provide an electric density signal which is dependent upon the density of the examination subject. The control system has an electromotor activated by a control circuit to which the density signal is applied and which activates the motor corresponding to the respective density signal for the purpose of selection of the correct filter. The transducers may be coupled with a device physically acting in compression on a body part of the patient to be examined such that the degree of resistance of the body part to compression is sensed by the transducers as a measure of patient density.