X-ray or gamma ray systems or devices – Source support – Including movable source
Reexamination Certificate
1999-08-09
2001-11-13
Porta, David P. (Department: 2876)
X-ray or gamma ray systems or devices
Source support
Including movable source
C378S195000, C378S196000
Reexamination Certificate
active
06315446
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the field of radiology instruments for acquiring images of a patient's body, which are principally usable in the medical field, in particular for cardiac or vascular examinations.
Radiology instruments with three axes of rotation are known, comprising an X-ray tube which is linked with a plane detector arranged opposite the tube and can occupy a plurality of positions in rotation in space around the body. These instruments are generally combined with a table, on which the patient rests and which can be moved in translation in the longitudinal direction of the patient's body, and in the height direction and in rotation about an axis transverse to the patient. The three axes of the radiology instrument are secant at a point which is referred to as the isocenter and on which the images which are obtained are centered.
For cardiac examinations, the region of the patient which is to be viewed is of small size in the length direction. For these examinations, a table with small-amplitude longitudinal travel is therefore used. Conversely, for vascular examinations, it is advantageous to be able to track the propagation of the contrast product which has been injected into the patient's vessels. It is therefore necessary to move the patient from his head to his feet so that each part of the patient passes successively through the isocenter of the radiology instrument. The consequence of this is that a table with large-amplitude longitudinal travel is necessary.
The X-ray tube and the image detector of the radiology instrument are arranged on either side of the patient, one of these elements being in general above the patient and the other below the table, and the table transparent to the X-rays. The space under the table therefore needs to be clear in line with the isocenter in order to not only position one of these elements, but also to move it with different angulations. A table provided with an off-center leg away from the isocenter should therefore be used, with the surface of the table overhanging relative to this leg. Such a table with large-amplitude longitudinal travel is bulky and heavy and undergoes high mechanical stresses. The table surface tends to flex when in the maximum extension position and is supporting a heavy patient, which may compromise the accuracy of the examinations carried out and the patient's comfort. The fact that it overhangs relative to the leg of the table may also be a source of psychological discomfort and stress for the patient. Furthermore, for equivalent technology, a large travel entails a greater motive force, which is a problem for the doctor.
A table is known whose leg is provided with a cam allowing two working positions, which is marketed by the company PHILIPS. The overhang is reduced by this arrangement. Nevertheless, this table may have a tendency to vibrate in response to the external environment, which impairs the accuracy of the examinations. The area which the table passes through when it is being moved from one position to another tends to increase in size and may cause a problem of safety for the staff in charge of handling it, as well as a problem with the cleanliness of the room in which it is located.
A radiology instrument with three axes is also known which is marketed by the company SIEMENS and in which the base is mounted on a cam allowing two longitudinally offset working positions. This instrument has similar drawbacks to the one mentioned above.
BRIEF SUMMARY OF THE INVENTION
It is therefore seen to be desirable to overcome the drawbacks of the known tables.
Thus there is a particular need to provide a radiology instrument which has a high degree of safety and allows full examinations of the patient.
In an embodiment of the invention the radiology instrument comprises an X-ray tube linked with a plane detector the plane of the detector being substantially perpendicular to a line of sight passing approximately through a focus of the tube and through a middle of this plane of the detector. The tube and the detector are capable of occupying positions in rotation around this body by means of a support device. The support device comprises a pedestal of overall L-shape resting on the floor, with a substantially horizontal base, a substantially vertical post and an axis of rotation passing through one end of the base. The post is fixed to the other end of the base and is parallel to the axis. A bracket is fixed to the top of the post and can rotate about a horizontal axis. A C-shaped arm is mounted on the bracket and is capable of rotating about an axis substantially perpendicular to the horizontal axis by sliding on the bracket. The tube and the detector being mounted on the bow and facing one another. The axis of the bracket and the axis of the arm are secant at a point in space referred to as the isocenter.
The instrument comprises means for moving the isocenter continuously along a patient's longitudinal axis. The patient may be held static or moved using the table. It is thus possible to take views with a plurality of relative longitudinal positions of the patient and the isocenter.
Preferably, the base of the pedestal is static in terms of translation relative to the floor. The means for moving the isocenter may be rotary.
Advantageously, an articulation about a substantially vertical fourth axis is arranged in the post, allowing an upper part of the instrument to rotate relative to a lower part of the instrument.
In one embodiment of the invention, isocenter, a point on the axis on the base of the pedestal and a point on the fourth axis form isosceles triangle in a horizontal plane, the base of an the triangle joining the isocenter and the point on the axis of the base of the pedestal.
In one embodiment of the invention the upper part of the instrument comprises the post, the bracket and the C-shaped arm, and the lower part of the instrument comprises the base.
In one embodiment of the invention, the upper part of the instrument comprises the bracket and the C-shaped arm, and the lower part of the instrument comprises the base and the post.
In one embodiment of the invention, the upper part of the instrument comprises a portion of the post, the bracket and the C-shaped arm, and the lower part of the instrument comprises the base and another portion of the post.
In one embodiment of the invention, the means for moving the isocenter is motorized.
The invention also relates to the use of an instrument for taking dynamic images of a static patient.
It is thus possible to use, for angiographic examinations, a table with short longitudinal travel of the type conventionally used for cardiac examinations. The taking of images and the movement of the isocenter can be synchronized so as to track contrast product spreading through the patient's vascular system by moving the X-ray tube and the detector along the patient. It is, of course, possible to combine movement of the table and movement of the isocenter in order to take images from one end of the patient's body to the other. Shifting the isocenter relative to the vertical axis of the base of the radiology instrument makes it possible to increase slightly the possibilities of angulation relative to the patient's body during cardiac examinations.
Finally, when a table is being used which tilts about a horizontal transverse axis arranged in its leg, the isocenter may be brought closer to the leg of the table, which decreases the elevation of the table due to its inclination and reduces the vertical travel needed in order to lower the table enough to maintain a satisfactory position of the patient relative to the isocenter. By reducing the required vertical travel of the table, its mechanical complexity, its mass and its cost are also reduced.
REFERENCES:
patent: 4298801 (1981-11-01), Heitman et al.
patent: 4358856 (1982-11-01), Stivender et al.
patent: 4363128 (1982-12-01), Grady et al.
patent: 4922512 (1990-05-01), Lajus et al.
patent: 4987585 (1991-01-01), Kidd et al.
patent: 03
Callier Bernard
Kidd Harold James
Chaskin Jay L.
GE Medical Systems S.A.
Porta David P.
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