X-ray or gamma ray systems or devices – Electronic circuit – Object responsive control
Reexamination Certificate
1999-11-01
2001-11-27
Dunn, Drew (Department: 2882)
X-ray or gamma ray systems or devices
Electronic circuit
Object responsive control
C378S008000
Reexamination Certificate
active
06324254
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention directed to a method and x-ray device for the pick-up of X-ray images of a vessel or organ that move substantially rhythmically, particularly for determining deposits in a vessel, particularly in a coronary vessel.
2. Description of the Prior Art
Usually an invasive method is used for the examination of vessels or organs. For example, for displaying coronary chalk, or stenoses that are generated by coronary chalk, a contrast medium is injected into the coronary arteries in an angiographic examination, and at the same time, this body section is examined by means of X-radiation, and X-ray images are picked-up with a high image frequency (typically 30 images per second). The contrast medium bolus can be held in the vessels for approximately 4 through 5 seconds; therefore, such a high image frequency is used in order to obtain a sufficient number of images. Although this method is very sensitive and specific, a disadvantage is the invasiveness, the injection of a contrast medium. This method is not appropriate for a fast and simple routine examination (screening), of the type suitable, for example, for an annual check-up of a person who may be at risk of developing coronary blockage.
Further, the utilization of a computed tomography system is known for obtaining a display of the coronary chalk, however, a computed tomography system is a highly complex and expensive device, which is usually not present in, or is very difficult to integrate with examinations that ensue there within a cardiologic department of a hospital or similar facility. For example, German OS 196 22 075 discloses the utilization of a computed tomography system for the radiological examination of different heart phases.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method that enables a simple examination of a vessel or an organ.
This object is achieved in accordance with the invention in a method and X-ray device wherein a number of digital X-ray images are picked-up during a slow motion of an X-ray pick-up system of an X-ray device, this slow motion ensuing along an orbit with an angular velocity smaller than 6° per second, and wherein the image pick-up is triggered by the vessel motion or organ motion or by an organ motion causative for the vessel motion determined during the system motion, and wherein a 3D image is reconstructed based on the individual images subsequent to the image pick-up.
The method can be implemented by an X-ray device in the form of a rotation angiography device with an angiographic C-arm at which the X-ray pick-up system is arranged, which is usually present in cardiologic departments, and allows a simple examination. In contrast to the known operating method of a rotation angiography device in the context of the invasive examination described above, wherein the X-ray system optimally fast (with an angular velocity >45° per second) rotates around an angle of approximately 200°, the inventive X-ray pick-up system rotates as slow as possible so that a long time is available for the image pick-up, which is not problematic since the examination given the inventive method is not dependent on the time within which a contrast medium can be held in the vessel. In order to assure that the picked-up single images are each picked-up at a moment in which the rhythmically moving vessel or organ is in the same position as in the previous image, the vessel motion or organ motion is identified or monitored, and this organ motion is utilized for triggering the image pick-up. The heartbeat frequency, for example, can be acquired for the triggering, since the heart, which pumps the blood through the surrounding vessels, causes the rhythmic vessel motion. After the image pick-up, a three-dimensional image is inventively reconstructed in which plaque deposits which may be present in the vessel can be recognized. Therefore, the inventive method advantageously uses the X-ray system and X-ray pick-up system that are known and utilized in the cardiology in order to be able to examine and show rhythmically moving vessels or organs with a non-invasive examination.
The movements of the X-ray image pickup system can advantageously ensue with an angular velocity <2° per second, particularly with 0.50 per second, and the speed of movement of the X-ray image pickup system can be selected dependent on the frequency of movement of the acquired vessel motions and organ motions, i.e. the angular velocity with which the image pick-up system moves can definitely be selected all the higher, the higher the heart frequency is. The speed of movement should be selected such that at least 300 images, particularly at least 400 images, are acquired during a motion cycle of the X-ray image pickup system in order to obtain a sufficient number of quasi “stroboscopic ” still image presentations of the heart, which are produced due to the motion triggering, for the 3D reconstruction. Inventively, the X-ray image pickup system itself can rotate around an angle of at least 150°, particularly of at least 200°.
The inventive X-ray device for the pick-up of X-ray images in a vessel examination or organ examination of a substantially rhythmically moving vessel or organ, particularly for the determination of deposits in a vessel, particularly in a coronary vessel, includes an X-ray image pickup system, which has an X-ray source and an X-ray receiver for the pick-up of digital 2D projection images from different projection angles of a subject to be examined and which, for this purpose, can be moved along a circular orbit with an angular velocity of less than 6° per second, an image processor for the reconstruction of a 3D image based on the 2D projection images, a control unit that controls the image pick-up mode, and a motion detection system for acquiring a vessel motion or organ motion or an organ motion that causes a vessel motion, which generates an output of motion-dependent signals. The motion detection system has a communication connection with the control unit, which also controls the movement of the X-ray image pickup system, and supply motion-dependent trigger signals thereto. The image pick-up mode is controllable dependent on the trigger signals. According to the invention, motion detection system can be an ECG device, with the heartbeat frequency being acquired for the generation of the trigger signals. The heart motion is relevant in examining the coronary arteries since it is this organ motion that causes the coronary vessel motion. Moreover, it is also possible to examine the heart or the heart muscle itself and the ventricles or the ventricle function; in this case, the heartbeat frequency also is acquired. To the extent that soft tissue resolution is sufficient in the reconstruction image generation, non-invasive examinations of the heart itself also can be undertaken with the inventive method and with the inventive device.
The invention is also directed to utilization of an X-ray device of the described type for the non-invasive examination of moving vessels that are close to the heart, particularly the coronary vessels, as well as the heart and the heart chambers themselves.
REFERENCES:
patent: 5228070 (1993-07-01), Mattson
patent: 5832051 (1998-11-01), Lutz
patent: 6031374 (2000-02-01), Epstein et al.
patent: 0026494 (1981-04-01), None
Dunn Drew
Schiff & Hardin & Waite
Siemens Aktiengesellschaft
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