X-ray or gamma ray systems or devices – Source support – Including movable source
Reexamination Certificate
1999-10-22
2001-04-24
Kim, Robert H. (Department: 2882)
X-ray or gamma ray systems or devices
Source support
Including movable source
C378S196000
Reexamination Certificate
active
06220752
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an X-ray examination apparatus which includes a patient table, a fluoroscopy image intensifier which is mounted on a first carriage so as to be displaceable in the longitudinal direction of the table, an overtable X-ray source which is aligned with respect to said intensifier and is coupled to the first carriage, and an image recording means which is displaceable on a second carriage.
2. Description of Related Art
Known apparatus of this kind usually include an X-ray image intensifier which serves as the fluoroscopy image intensifier and a moving grid for receiving a film cassette as the image recording device. This necessitates a very fast change over between image recording and X-ray fluoroscopy. During an exposure, the moving grid with the film cassette is situated between the X-ray image intensifier and the X-ray source. During fluoroscopy, however, the film cassette must be moved out of the beam path of the X-ray tube to a parking position. To this end, known X-ray examination apparatus of the kind set forth include a first carriage which is displaceable in the longitudinal direction of the table and carries an X-ray image intensifier and a spot film device within which a second carriage with the film cassette can be displaced perpendicularly to the longitudinal direction of the table. A spot film device of this kind is intricate and makes it necessary for the X-ray examination apparatus to be wide enough so as to enable lateral displacement of the second carriage to the parking position.
Citation of a reference herein, or throughout this specification, is not to construed as an admission that such reference is prior art to the Applicants' invention of the invention subsequently claimed.
SUMMARY OF THE INVENTION
It is an object of the present invention to realize, while using simple means, an X-ray examination apparatus of the kind set forth which has a compact construction. This object is achieved according to the invention in that the second carriage is displaceable in the longitudinal direction of the table, independently of the first carriage, and that there is provided a drive system which displaces the two carriages in synchronism in a first mode of operation and displaces the second carriage relative to the first carriage in a second mode of operation.
According to the invention, the second carriage is displaceable in the longitudinal direction of the table, independently of the first carriage, i.e. with respect to the recording position, the parking position is shifted in the longitudinal direction of the table so that the lateral dimensions of the X-ray examination apparatus are not increased. In the first mode of operation the two carriages are displaced in synchronism with one another, the second carriage remaining in a defined position relative to the first carriage, for example in a parking position directly adjacent the first carriage. In order to perform an X-ray exposure, only a comparatively small displacement of the second carriage will then be required in the second mode of operation, irrespective of the position of the first carriage.
The drive system could be realized, for example by way of two spindle drives operative in the longitudinal direction of the table. In the first drive mode the two spindle drives would operate in synchronism, thus driving also the two carriages in synchronism, whereas in the second mode of operation one spindle drive is stationary and the second spindle drive is active and displaces the second carriage. In describes an even simpler construction, the drive system further comprises a drive which is active in the first mode of operation so as to displace the first carriage, and wherein the apparatus further comprises a first drum which rotates in the second mode of operation, and at least one pulling means which can be wound onto and from the first drum and is guided, via guide means on the first and the second carriage, in a first and a second loop, said pulling means being attached at one end of the patient table, the length of the loops changing in opposite directions upon rotation of the first drum. In this context an oppositely directed change of the loop length is to be understood to mean that the length of one loop increases when the length of the other loop decreases and vice versa. When the drive for the first carriage is stationary and the drum rotates (second mode of operation), one loop becomes shorter and the other loop becomes longer, the guide means on the second carriage then displacing this carriage relative to the first carriage. However, when the first carriage is displaced by the drive in the first mode of operation and the drum is stationary, the second carriage cannot be displaced relative to the first carriage, because for such a displacement one of the two loops would have to become longer; however, this is impossible in the stationary condition of the drum.
The embodiment wherein the first drum on the one side and the pulling means on the other side are attached to opposite ends of the patient table, viewed in the longitudinal direction, enables examination of a patient in the entire region between the two ends of the frame, i.e. the fluoroscopy image intensifier can be displaced from the head end to the foot end.
In principle there could be provided two pulling means whose ends are connected to the drum and which are wound onto this drum in opposite directions, so that one pulling means would be wound onto the drum while the other is unwound therefrom during rotation of the drum. In simpler embodiment, there is provided only a single pulling means whose ends are connected to the patient table via the loops, the central part of said pulling means being wound on and attached to the first drum. The embodiment wherein the ends of the pulling means are guided via respective guide means on the first and the second carriage, wherein the sum of the diameters of the guide means corresponds to the diameter of the first drum, and wherein the ends of the pulling means are guided in such a manner that outside the guide means a parallel trajectory is obtained in the longitudinal direction of the table that outside the guide pulley the pulling means extends parallel to the longitudinal direction of the table everywhere.
In an X-ray examination apparatus in which the image recording means is displaced transversely of the longitudinal direction of the table in a spot film device, the image recording means can be shielded from scattered radiation, produced before and after the exposure during fluoroscopy, by means of a shield which is rigidly connected to the spot film device and is impervious to X-rays. In an apparatus in which the parking position is shifted in the longitudinal direction of the table, a stationary shield cannot shield the image recording means in the parking position from the scattered radiation produced during fluoroscopy, because such a shield would constrict the zone in which fluoroscopy or image recording is possible. The embodiment further comprising a scattered radiation shield which is mounted on the second carriage and which is displaceable in the direction transversely to the longitudinal direction of the table and is coupled to the drive system in such a manner that it shields the image recording means when the second carriage is centered with respect to the first carriage, and which leaves the image recording means free when the second carriage is in a parking position to the side of the first carriage provides shielding from scattered radiation by means of a scattered radiation shield which is displaceable transversely of the longitudinal direction of the table.
Without utilizing a separate drive for the scattered radiation shield, in a further embodiment further comprising a second drum which is coupled to the first drum and on which there can be wound a pulling means which is guided in a loop via guide means on the second carriage and on the scattered radiation shield and is connected to the frame in s
Barnavàri Attila
Csikòs Ja{grave over (n)}os
Medgyesi Gyorgy
Kiknadze Irakli
Kim Robert H.
U.S. Philips Corporation
Vodopia John F.
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