X-ray or gamma ray systems or devices – Electronic circuit – With display or signaling
Reexamination Certificate
1999-12-07
2001-07-17
Bruce, David V. (Department: 2882)
X-ray or gamma ray systems or devices
Electronic circuit
With display or signaling
C378S095000, C378S098800
Reexamination Certificate
active
06263044
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an X-ray examination apparatus which includes:
means for generating an X-ray image of an object, which X-ray image generating means have a brightness control input, and
image processing means coupled to the X-ray image generating means in order to output a brightness control signal to said brightness control input.
The present invention also relates to a method for deriving a brightness control signal from information of an object in the X-ray image.
2. Description of Related Art
Such an apparatus and method are known from EP-A-0 629 105 which discloses in particular image processing means equipped with a light detection system wherein a CCD detector signal representing relative spatial intensity data of the X-ray image and a photodetector signal representing absolute intensity data of the X-ray image are multiplied so as to produce a desired brightness control signal. The known apparatus utilizes an image processor so as to define so-called measuring fields which contain selected image information which is relevant for basing the brightness control signal thereon. The measuring fields are selected either manually or automatically. In case of automatic selection of measuring fields, some intelligence is included in the image processor in order to select relevant pixels from registered pixels of the image.
Citation of a reference herein, or throughout this specification, is not to construed as an admission that such reference is prior art to the Applicant's invention of the invention subsequently claimed.
SUMMARY OF THE INVENTION
It is an object of the present invention to extend the field of application of the X-ray examination apparatus and to improve the image quality by offering additional possibilities for the selection of measuring fields in an X-ray image and for the identification of objects in the X-ray image.
To this end, the X-ray examination apparatus according to the present invention is characterized in that the X-ray image generating means are provided with an X-ray data output, that the image processing means are provided with an X-ray data input coupled to the X-ray data output, and that the image processing means are arranged as calculating means for calculating absorption properties of the object and for generating the brightness control signal in dependence on said absorption properties.
Similarly, the method according to the invention is characterized in that the information for deriving the brightness control signal results from the calculation of absorption properties of the object or parts thereof.
Selecting measuring fields on the basis of calculated absorption properties of the object reproduced in the X-ray image allows for a more intelligent measuring field selection, because parts of the objects which are relevant to the brightness control can now be identified by way of their absorption properties. For example, bones, organs, brains, pins, bolts and tissues, but also so called direct radiation can be intelligently identified automatically. Additionally, the brightness control signal can mainly be based on said identified object parts so as to optimize image quality, visibility and contrast of such parts in order to augment the possibilities of examination and analysis thereof. Advantageously, comparison of absolute brightness levels of specified objects, or parts thereof, on the basic of calculated absolute absorption figures is possible too, which is beneficial to the diagnoses to the made by a physician.
An embodiment of the X-ray examination apparatus according to the invention has the features that the object absorption calculating means are arranged as calculation means wherein the absorption of the object is calculated relative to the absorption rate of a reference substance. Calculations where the absorption rate is only related and calculated relative to a reference substance require only moderately complex and hence advantageously cheaper and faster operating calculation means. Furthermore, brightness control based on relative calculations does not necessitate laborious explicit calculations of absorption rates of object parts in the X-ray image.
From a medical point of view, water is a preferred reference substance in a further embodiment of the X-ray examination apparatus according to the invention. Generally speaking, the reference substance can be chosen from a group including: water, air, calcium, iodine, barium, iron or a synthetic material such as plastic.
A further embodiment yet of the X-ray examination apparatus according to the invention has the features that the object absorption calculating means include an application parameter input for inputting a signal which is representative of an absorption profile defining a contribution area wherefrom information is selectively taken in order to derive the brightness control signal therefrom. The application parameter input can advantageously be used for selecting a specific contribution area of interest in the X-ray image in dependence on, or example the kind of or combination of objects, such as bones, brains, lungs, tissues etc. to e imaged.
Another embodiment of the X-ray image apparatus according to the invention is equipped with Fuzzy Logic means for defining a Fuzzy Logic rule dependent contribution area. This improves the image quality of specific image parts whose absorption lies in said contribution area.
Still a further embodiment of the X-ray apparatus according to the invention has the features that the X-ray data output of the X-ray image generating means provides information about, for example a driving current and/or driving voltage applied to the X-ray image generating means, a distance between an X-ray source and an image intensifier in the X-ray image generating means, the image format of the image intensifier and/or other parameters such as application parameters which are considered relevant for the calculation of absorption. The aforementioned information and the inclusion of one or more parameters listed above determines the accuracy of the absorption calculations and the brightness control.
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patent: 5664000 (1997-09-01), Van Woezik et al.
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patent: 5923724 (1999-07-01), Soukal
patent: 6175614 (2001-01-01), Jensen et al.
patent: 0629105A1 (1994-12-01), None
Bruce David V.
Dunn Drew A.
U.S. Philips Corporation
Vodopia John F.
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