X-ray or gamma ray systems or devices – Specific application – Stereoscopy
Patent
1984-09-25
1986-08-12
Church, Craig E.
X-ray or gamma ray systems or devices
Specific application
Stereoscopy
378148, 378150, 378170, G03C 900
Patent
active
046060634
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a shutter arrangement for intra-oral radiographic X-ray apparatus of the kind which comprise a punctiform X-ray source; a radiation screening and directing X-ray tube; a holder for an object and for an X-ray film or plate, located externally of the radiation-exit orifice of the X-ray tube, said holder being adjustable to at least two positions in a direction transversely to the direction of the radiation, to produce at least two images of the object in two different positions relative to the radiation, for example for stereoscopic reproduction in dental diagnosis; and a shutter which is arranged between the X-ray source and the holder and which has a shutter aperture which is adapted to the size of the X-ray film or plate, whereby the shape and size of the beam passing through the aperture substantially coincides with the shape and size of the film or plate, in the plane thereof.
One disadvantage with such known shutter arrangements is that the clarity of the picture obtained is not always satisfactory, for example is blurred as a result of movement. Another disadvantage is that the amount of X-ray radiation to which the patient is subjected is relatively high. Consequently, an object of the present invention is to provide a shutter arrangement by means of which these and other disadvantages inherent with known shutter arrangements of the aforementioned kind can be overcome.
Accordingly, this invention consists in a shutter system of the kind described in the introduction, characterized in that the shutter comprises a metal plate which is provided with a shutter aperture and which is mounted in the exit orifice of the X-ray tube in a manner which enables it to be displaced in a slide path transversely to the beam direction, said slide path and said metal plate being provided with mutually co-acting means which define snap-in locations for the metal plate and which correspond to respective positions of the holder.
In a further embodiment of the invention, in which the holder can be adjusted between at least two fixed positions of alignment lying in a plane entending perpendicularly to a central beam of radiation in the beam bundle, the shutter is arranged so that when being adjusted from one position to another it moves in parallel in a plane parallel with said perpendicular plane.
When using the shutter arrangement according to the invention, the quality of the three-dimensional X-ray pictures obtained is considerably improved, inter alia because there is no blurring due to movement. The shutter arrangement according to the invention also permits smaller radiation dosages to be administered than was hitherto the case.
So that the invention will be more readily understood and further features thereof made apparent, an exemplary embodiment of the invention will now be described with reference to the accompanying drawings, in which
FIG. 1 illustrates schematically and in plan view an X-ray apparatus provided with a shutter system according to the invention;
FIG. 2 is a side view of the apparatus illustrated in FIG. 1;
FIG. 3 illustrates the shutter system with the metal plate fitted;
FIG. 4 illustrates the shutter arrangement with the metal plate inserted; and
FIG. 5 illustrates three mutually different metal plates which are included in the shutter arrangement.
The ancillary apparatus for intra-oral radiography comprises three major parts, namely a holder 10 provided with a bite plate, a film-holder shaft 11, and a shutter arrangement incorporated in the X-ray beam exit orifice 5 of the X-ray tube 3. The X-ray beams are derived from a beam source 1, and are allowed to pass through a close-up shutter 2 in the inlet orifice of the X-ray tube.
The film holder 10 is made of metal and comprises the aforementioned bite plate and a back piece, into which the film or plate is inserted. As will be seen from FIG. 2, The back piece forms an obtuse angle with the bite plate, so that the film can be comfortably placed in the jaw region of the patient. Means (not shown) are provided for lo
REFERENCES:
patent: 3745344 (1973-07-01), Updegrave
patent: 4109156 (1978-08-01), Schroeder
patent: 4166220 (1979-08-01), Stutts
patent: 4221971 (1980-09-01), Burger
patent: 4507798 (1985-03-01), Welander
Church Craig E.
Grigsby T. N.
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