U.S. Philips Corporation

Lunar Corporation

Cornelis H Slump

Geert Jan Laanstra

David L Ergun

David R Strait

Hendrik Kuipers

Rudolph M Snoeren

Marius Brok

Marcel J Dykema

Marcel J Dijkstra

Hans Sjoerd Peter Van Der Schaar

Marton O Harms

Hans Sjoerd Van Der Schaar

An x-ray imaging system provides automatic adjustment of x-ray tube voltage and current as deduced from two exposures at different voltages. Real-time image distortion removal and image rotation are accomplished by computer processing using a generalized image transformation polynomial. Scatter in the image is reduced by calculating a scatter map based on a blurring of the received image and normalizing the scatter map to point scatter measurements made with an x-ray occluder eliminating direct exposure of certain areas of the image. Improved signal to noise ratio in a moving x-ray image is provided by averaging stationary portions of the image over a longer time than the moving portions of the image. A non-linear white compression function further reduced image noise by transforming the raw image to a gray scale having equal noise intervals.

X-ray imaging system

An x-ray imaging system provides automatic adjustment of x-ray tube voltage and current based on an identification and removal of background pixels in the image and a calculation of the functional relationship between voltage and current and dose for the particular imaged object as deduced from two exposures at different voltages. Real-time image distortion removal and image rotation are accomplished by computer processing using a generalized image transformation polynomial. Scatter in the image is reduced by calculating a scatter map based on a blurring of the received image and normalizing the scatter map to point scatter measurements made with an x-ray occluder eliminating direct exposure of certain areas of the image. Improved signal to noise ratio in a moving x-ray image is provided by averaging stationary portions of the image over a longer time than the moving portions of the image. A non-linear white compression function further reduced image noise by transforming the raw image to a gray scale having equal noise intervals.

An imaging arrangement including a multi-sensor for use in an x-ray examination apparatus is described that combines a plurality of partially overlapping sub-images, resulting in an increased effective sensor area when compared to a single sensor-image. Thus an imaging arrangement is provided suitable for imaging a large area output screen of an image intensifier by way of semiconductor image sensors. Image artifacts owing to variations in the alignment of the respective image sensors are corrected for by applying geometric transformation to respective electronic sub-image generated by the image sensors. The transformed electronic sub-images are assembled into a recombined image. Further image quality improvement is obtained by performing evening operations in overlapping regions of the transformed sub-images.

X-ray examination apparatus with an imaging arrangement having a

A periodically moving object, e.g., the heart, is X-rayed in response to periodic pulses generated at instances in the period at which the object is anticipated to be in a given position. Stochastic movements shift the position of the object at those instances such that image artifacts may result. A prediction methodology is utilized to predict when the object has moved stochastically and therefore will be out of position at the forthcoming pulse. That forthcoming pulse is then suppressed to preclude imaging the object out of position. Kalman filtering is utilized in the prediction methodology.

X-ray exposure synchronization method and apparatus

The modulation transfer function of a digital imaging system is measured using a test object comprising a number of slits. The effect of geometrical distortions on the MTF measurement, is minimized by making the dimension of the test object as small as possible with respect to the image detector. The minimum slit spacing d enabling suitable MTF measurement is expressed in the number of pixels N over a dimension L of the image detector: d&gt;8L/N.

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Oldenzaal, Netherlands

Cornelis H Slump