U.S. Philips Corporation

Walter Hillen

Ulrich Schiebel

Stephan G Rupp

Norbert Conrads

Peter J Quadflieg

Ingo Schafer

Hanns-Ingo Maack

Rudolph M Snoeren

Josef N Conrads

Gottfried Frings

A device for scanning an X-ray image where a previously locally uniformly charged photoconductor (1) is discharged in dependence on the local intensity, utilizing several electrometer probes which are arranged in a row and which line-wise scan the charge pattern of the photoconductor (1) which is successively displaced in the scanning direction, extending perpendicular to the line direction, the probes supplying, for each pixel, an image value which corresponds to a discharge at the relevant pixel. In order to eliminate streaky artefacts, the image values are applied to an analog-to-digital converter (5), the converted values being stored in an image memory (6), there being provided a signal processor (7) which subjects the image values of neighboring pixels in an image line to a low-pass filter function and which subjects the image values of pixels neighboring one another in the scanning direction to a high-pass filter function.

Device for scanning an X-ray image

The invention relates to a method of generating X-ray images by means of a photoconductor which is provided on a conductive substrate and whose surface potential can be read by means of probes, and also relates to a device suitable for carrying out the method. In order to avoid image artefacts which could be caused by deviating sensitivities of the probes or by frequency-dependent distortions, after the charging of the photoconductor the substrate potential is varied during a test phase. Test data is generated which correspond to the spatial or temporal variation of the potential on the surface of the photoconductor; from this test data there is formed correction data which is stored in order to correct the image data of a subsequent X-ray exposure.

Method of generating X-ray images and device suitable for carrying out

X-ray images are generated from a CCD image sensor having an image section and at least one storage section by performing a first X-ray exposure during a first time interval (T.sub.1) which is shorter than the read-out period (T.sub.r) of an image stored in the storage section of the CCD image sensor (7) to form a first image in the image section, transferring the first image from the image section to the storage section after expiration of the first time interval (T.sub.1), performing a second X-ray exposure directly after or a small interval in time after the first X-ray exposure during a second time interval (T.sub.2) which is short in comparison with the read-out period (T.sub.r) to form a second image in the image section, reading out the first image from the storage section and writing the first image into a further memory, transferring the second image from the image section to the storage section after reading out the first image, and reading out the second image and summing it with the first image written in the further memory.

Method of generating X-ray images, and X-ray apparatus for carrying out

At least one primary diaphragm comprises two elements displaceable so as to form a linear fan-shaped beam which is incident on an object to be examined. The elements form the slit-shaped aperture forming the fan beam in their normal X-ray beam forming position and are moveable to a respective, selectable limit position perpendicularly to the fan shaped beam in order to define and mark an examination zone greater in cross-section area than the fan beam with a light beam. Light incident on the examination zone is restricted by the diaphragm elements in their limit positions, thus marking the examination zone with the light beam. X-ray exposure of the object to be examined takes place only when the elements are between the two positions defining the examination zone of the primary diaphragm where its diaphragm elements occupy in their respective limit positions.

Slit diaphragm system defining X-ray examination zone with visible light

A plurality of electrometer probes scan the charge pattern of a photoconductor (1), the distance between the electrometer probes (6) and the photoconductor (1) being measured via an alternating voltage applied to the photoconductor (1). The alternating voltage is scanned by the electrometer probes and is filtered out to extract distance measuring signals. The output signals of all electrometer probes (6) are used for determining image values of the X-ray image, the output signals of at least some of the electrometer probes (6) also being used, via a suitable filter (23), for determining the distance measuring signals. An adjusting device adjusts the distance between the electrometer probes (6) and the photoconductor (1) continuously to a reference value, in dependence on the value of the measuring signals, during the scanning operation.

A plurality of electrometer probes (3, 4, 5, 6) scan charge patterns of a photoconductor (1) which is locally uniformly charged prior to the X-ray exposure and is discharged by the exposure in dependence on the intensity of the X-rays. The surface of the photoconductor is scanned after the exposure in order to determine the charge density, the electrometer probes (3, 4, 5, 6) forming for each pixel a pixel value which corresponds to the discharge at the relevant pixel to compensate for sensitivity fluctuations of the electrometer probes included is a calibration operation for the sensitivity of all electrometer probes in that two probes (3, 4, 5, 6) scan an identical section (a.sub.1 . . . d.sub.3) of the image, their relative sensitivity used for correcting the pixel values is derived from comparison of the resultant output signals of the probes (3, 4, 5, 6).

Method of scanning an X-ray image by means of electrometer probes, and

The invention relates to a device for producing X-ray images by means of a photoconductor which converts X-rays into a charge pattern, which photoconductor is charged prior to the X-ray exposure, its surface being scanned after the exposure in order to detect the charge pattern. Artefacts are liable to occur in an X-ray image when the exposure directly follows an X-ray exposure during which the photoconductor has received, at least in given areas, a high dose. These artegacts are avoided in accordance with the invention in that there is provided a recharging device which limits the decrease of the charge density on the surface of the photoconductor during the X-ray exposure to a predetermined value.

Device for producing x-ray images by means of a photoconductor

The invention relates to a method of producing an X-ray exposure is provided by a photoconductor, which converts X-radiation into a charge pattern, is evenly charged locally before the X-ray exposure, is discharged by the exposure as a function of the intensity of the X-radiation and the surface of which is scanned after the exposure for detecting the charge density, an image value being formed for each image point, corresponding to the discharge at the image point. The measured image values may be falsified by the self-discharge of the photoconductor induced by X-radiation. Since the self-discharge always proceeds in accordance with the same time laws, the self-discharge effects are corrected utilizing the time of the scanning instants, i.e., position in time with respect to the X-ray exposure and the end of the charging of the photoconductor in conjunction with a characteristic discharge function of the photoconductor and a correction factor.

Method of producing an X-ray exposure by means of a photoconductor and

A photodetector CCD pick-up device reads a storage phosphor record carrier via a light source on one side of the carrier with the photodetector device on the other side of the carrier. A drive displaces the carrier relative to the light source and to the CCD device. The light source illuminates the phosphor sub-surface of the record carrier to produce fluorescent light and which sub-surface comprises a plurality of pixels. The CCD pick-up device is arranged so that the charges in its cells produced by the fluorescent light displace in the same direction and at the same speed as the carrier.

System including a CCD imager device for reading a storage phosphor

The invention relates to the elimination of streak-like artefacts in slit radiography which are caused by an axial excursion of the rotary anode X-ray tube used for making the radiographs. These streaks can be eliminated by adapting the speed of displacement of the X-ray beam, the number of revolutions per unit time of the anode and the intensity profile of the radiation beam to one another so that for each point the intensity modulation in the half-shade area, caused by the periodic displacement of the focal point, is compensated for.

X-ray apparatus for slit radiography

An electrostatic induction probe arrangement using several probes. The probe electrodes and the screen electrodes surrounding them are fitted to the end faces of a substrate arrangement, and the conducting paths leading to the preamplifiers are arranged in several parallel planes, perpendicular to the end face, in such a way that the signal-conducting paths connected to the probe electrodes are essentially screened by the screen-conducting paths connected to the screen electrodes.

Electrostatic induction probe arrangement using several probes

A method and apparatus for producing an X-ray exposure by means of a photoconductor. Photoconductor defect locations which appear as artefacts in the X-ray image are eliminated by subtracting a compensated dark discharge image from the X-ray image.

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Aachen, Germany

Walter Hillen