Patent Description:
The history of medical X-ray imaging originates approximately to the time of inventing X-ray radiation. For more advanced ways of imaging e.g. in the dental field, the developing of panoramic X-ray imaging begun for over a half century ago. The advancement of digital imaging especially in the <NUM> brought digital X-ray imaging apparatuses also to dental practices. The latest development in the dental field has been generalization of the cone-beam computed tomography apparatuses designed for three-dimensional imaging of teeth and other bones of the cranial area. Among other things, computed tomography enables imaging both the cranial bones and teeth as well as soft tissues. Along with many other reasons, the generalization of odontological computed tomography imaging has been contributed, among other things, by being able to get soft tissues of the cranial area better visible in computed tomography images than e.g. in conventional radiographs of the cranial area.

In connection with the X-ray imaging of persons, one must try to provide for not to expose the patient to radiation more than necessary for making a diagnosis. The amount of the radiation dose can be affected, among other things, by choosing the best applicable imaging technology for each situation and by developing the actual imaging techniques. A typical problem causing extra radiation stress is, however, a failure in imaging, whereby the patient has to be reimaged. As the imaging may last even about twenty seconds, a typical reason for the failure in imaging is that the patient moves or stirs during the imaging.

The field of odontology commonly employs X-ray apparatuses where the patient sits or stands positioned at a patient support means during the imaging. Commonly found structures in such support means are e.g. a chin support, a bite support, support rails which position on the patient's temples and mostly provide sideways pointed support, and a forehead support. Known are also structures which are arranged to support the occiput.

In odontological panoramic and cone-beam computed tomography imagings, for instance, where the imaging means rotate around the patient's head and the imaging event typically lasts of the order of <NUM>-<NUM> seconds, the large-size C-arm rotating around the head in front of the patient's face can easily frighten the patient. Also otherwise due to the duration of the imaging event, the patient might try to move his/her head out of its place or turn it during an exposure.

In many patient support arrangements according to prior art, the primary purpose is to position the anatomy being imaged to a desired point while the structure has not necessarily been designed especially for assisting keeping the head in its place but for the most in some specific direction or directions. The support structure can also be such that it is challenging to use it as a support for patients of different sizes and/or a patient it may find it uncomfortable. It is also possible that a structure designed for a particular support function can impede the operations of the person assisting the imaging e.g. when the purpose is to use in the imaging also some other support structure for additional support, or when the use of the support structure requires repetitive moving to the other side of the patient. The support structures are also associated with patient safety aspects which have not necessarily been fully considered in all solutions.

JPH05110U discloses a device according to the preamble of claim <NUM>.

The object of the invention is to provide a novel kind patient support arrangement for an odontological X-ray apparatus which can e.g. facilitate patient positioning.

As an example of advantages provided by the invention one can refer to wheelchair users the positioning of whom for imaging can be challenging in arrangements according to prior art. The present invention presents an arrangement by which imaging of a wheelchair user can be easily implemented with a similar support as when imaging of e.g. a patient standing independently on his/her own two feet. On the other hand, the invention with its preferable embodiments provide a support arrangement which, considering an X-ray imaging apparatus which is also arranged with means to image the patient optically, offers a possibility to arrange free space to image both the facial area and the area of temples and ears without at the same time imaging also the patient support means.

The principal characteristics of the invention are described in the accompanying patent claims.

Next, the invention and its preferable embodiments will be described in more detail and with reference to the attached figures.

<FIG> shows an X-ray imaging apparatus <NUM> including a vertical support structure <NUM> from which horizontally extend a structure <NUM> supporting patient support means <NUM> and an arm part <NUM> which supports a structure supporting imaging means, an arm part <NUM>. To the arm part <NUM> supporting the imaging means are arranged at a distance from each other the X-ray imaging means of the apparatus, i.e. an X-ray radiation source <NUM> and a receiver of X-ray image information <NUM>, which have been positioned to the apparatus with respect to the patient support means <NUM> such that to the apparatus is formed an imaging station <NUM>, which takes its position between the X-ray radiation source <NUM> and the receiver of X-ray image information <NUM> such that a beam produced by the X-ray radiation source <NUM> may be directed to pass via the imaging station <NUM> towards the receiver of X-ray imaging information <NUM>. The arm part <NUM> supporting these imaging means is arranged rotatable and also its position with respect to the structure supporting it <NUM> and/or the patient support station <NUM> may be arranged changeable. The apparatus includes control means, of which, <FIG> shows a control panel <NUM> positioned in connection with the arm supporting the patient support means <NUM>. The apparatus <NUM> can be arranged via a cable into connection with a computer <NUM> which can be arranged with a means for processing image information produced by the apparatus and a display <NUM> which can display images.

The basic structure of the X-ray imaging apparatus shown in <FIG> corresponds to the basic structure of the apparatus shown in <FIG>. As an essential difference in view of the patient support structure comprising a forehead support shown in <FIG>, <FIG> shows a rest structure setting on the occiput. <FIG> shows a side view of such patient support structure setting on the occiput.

A rear rest structure <NUM> shown in <FIG> and <FIG> comprises an actual support part <NUM> setting against the skull and a supporting structure <NUM> diverging from it.

In the embodiment according to <FIG> and <FIG>, the supporting structure <NUM> consists of an elongated structure, a first end of which containing the above-mentioned support part <NUM> and which extends on a different side of the imaging station <NUM> as where the support part <NUM> is located. A second end <NUM>' of the supporting structure <NUM> of the rear rest structure extends for a distance past its mounting point to the X-ray imaging apparatus <NUM>. The shape of the supporting structure <NUM> can be some other than the one shown in <FIG> and <FIG> and can e.g. only comprise an elongated, possibly arm-like structure.

In the embodiment according to <FIG> and <FIG>, a surface of the support part <NUM> of the rear rest structure pointing towards the imaging station <NUM> is arranged curved in the direction of the imaging station <NUM>, substantially to correspond a curvature of a skull. The radius of curvature of that surface curving towards the imaging station <NUM> can be implemented such that it is not constant but the surface comprises an area in the middle part of the curve where the radius of curvature is smaller than the one in the edge area of the curve. Implemented as such, the support part <NUM> adapts better than an evenly curved surface to support skulls of different sizes and also gives support to prevent the head from turning.

In <FIG>, the rear rest structure <NUM>, in more detail the supporting structure <NUM> contained by it, is mounted to the X-ray imaging apparatus by a mounting structure <NUM> which can be arranged to enable adjustment of the mounting point of the rear rest structure <NUM> to the X-ray imaging apparatus. This way, a section <NUM>' of the rear rest structure <NUM> extending past its mounting point to the X-ray imaging apparatus <NUM> functions as a practical grabbing means when the mounting structure <NUM> of the rear rest structure has been arranged to enable a detachable mounting of the rear rest support <NUM> and when wanting to adjust the position of the support structure <NUM>.

<FIG> and <FIG> illustrate the implementation of the rear rest structure <NUM> such that the support part <NUM> of the rear rest structure <NUM> sets on a higher horizontal plane than its mounting point to the X-ray imaging apparatus <NUM>.

In one preferred embodiment of the invention, the supporting structure <NUM> of the rear rest structure <NUM> comprises an elongated arm-like structure which sets at its mounting point to the X-ray imaging apparatus <NUM> such that the supporting structure <NUM> extends towards the support part <NUM> at an angle of <NUM>-<NUM> degrees with respect to the horizontal plane. Preferably, this angle is about <NUM> degrees which approximately equals the angle of a line connecting the anatomies 'tip of chin' and 'middle of occiput' with respect to the horizontal plane, when the head is in an upright position and the gaze towards the horizon. The measure from the `tip of chin' to the `middle of occiput' can be utilized when adjusting imaging parameter values used in X-ray imaging to correspond characteristics of the anatomy being imaged at a time.

When the rear rest structure <NUM> and its mounting to the X-ray apparatus is implemented such that the support part <NUM> of the rear rest structure moves when adjusting its position on a line or on a plane having the angle with respect to the horizontal plane of approximately said about <NUM> degrees, such as between <NUM>-<NUM> degrees, an arrangement is provided by means of which it is possible to obtain with simple operations particularly the measure from the 'tip of chin' to the `middle of occiput' of an anatomy being imaged at a given time, which measure illustrates the size differences between skulls better than e.g. the differences in skulls' horizontal dimension. One way to implement this kind of an arrangement is to arrange the supporting structure <NUM> of the rear rest structure comprising a substantially linear part which is arranged movable but also mountable to a groove or a sleeve of substantially equal size, which then operates as the mounting structure <NUM> of the rear rest structure and which is arranged to the X-ray apparatus such that said substantially linear part of the supporting structure <NUM> of the rear rest structure is positioned at the above-mentioned angle with respect to the horizontal plane.

In one embodiment of the invention, the patient support means <NUM> of the X-ray imaging apparatus comprises a chin support structure or a bite support structure <NUM> and the line or the plane mentioned in the previous chapter is arranged to pass substantially via the point to which the patient's anatomy is designed to be positioned to said chin or bite support structure <NUM>.

To the X-ray imaging apparatus, it is possible to arrange identification means to indicate or identify the above-discussed measure - or some other known distance the correlation of which to said distance is known. Thus, when the distance of the support part <NUM> of the rear rest structure from the mounting point of the rear rest structure <NUM> to the X-ray apparatus is arranged adjustable, it is possible to arrange to the X-ray imaging apparatus identification means to indicate or identify this distance, or the distance of the support part <NUM> from some other reference structure of the X-ray apparatus. In connection with the mounting point of the rear rest structure <NUM> to the X-ray apparatus, foe example, there may be means to measure or observe the distance of some identifiable point in the rear rest structure <NUM> from a known reference point, or the rear rest structure <NUM> may be arranged with a scale arranged to always be measured from the same point of the X-ray apparatus which then directly gives the position of the rear rest structure <NUM> within its operation area and, thus, e.g. the distance from the support part <NUM> of the rear rest structure to the chin or bite support of the X-ray apparatus.

That measure may also be basis for e.g. a warning signal on that a motion path of the imaging means <NUM>, <NUM> intended for use in X-ray imaging is getting so close to the patient that it is best to consider adjusting the path of movement to be different, before starting the imaging. That measure may thus indicate that the rear rest structure <NUM> is positioned at a place which is in the area of the part of movement of the imaging means <NUM>, <NUM> during imaging, or at a distance closer than predetermined to such an area.

<FIG> shows a jointed structure <NUM> arranged in the area between the mounting point of the rear rest structure <NUM> to the X-ray imaging apparatus <NUM> and the support part <NUM> of the rear rest structure which is arranged to operate as a safety mechanism <NUM> in the case of the patient passing out or having a panic attack during the imaging. If the patient has been positioned e.g. both in the chin and rear rest support, there is a theoretical risk of injury if neither of the supports give way when the patient is wedged between those support structures. Hence, such a safety mechanism can be arranged to go off e.g. when force greater than predetermined is acting on the support part <NUM> of the rear rest structure, the identification of which situation may then release the support part <NUM> from its patient support position. the above-mentioned jointed structure <NUM> arranged in the supporting structure <NUM> of the support part <NUM> of the rear rest structure <NUM> can be arranged to turn when a moment acting on it exceeds a specified limit value.

In the embodiment according to <FIG>, the supporting structure <NUM> of the patient support means <NUM> is arranged with a second mounting structure <NUM> to which a chin support or a bite support <NUM> can be mounted.

Claim 1:
An X-ray imaging apparatus for imaging a skull or a partial area of the skull, which apparatus comprises:
- a substantially vertical frame part (<NUM>);
- an X-ray radiation source (<NUM>) and a receiver of X-ray radiation (<NUM>) which together form X-ray imaging means (<NUM>, <NUM>);
- a control system of the X-ray imaging means;
- an imaging station (<NUM>) positioned in an area between the X-ray radiation source (<NUM>) and the receiver of X-ray radiation (<NUM>);
- a patient support means (<NUM>) arranged in connection with the imaging station (<NUM>) for supporting an anatomy being imaged;
- which patient support means (<NUM>) for supporting the anatomy being imaged comprise a rear rest structure (<NUM>) containing a support part (<NUM>), which support part (<NUM>) is arranged to get positioned at occipital area,
characterized in that said rear rest structure (<NUM>) comprises a first elongated supporting structure (<NUM>), a first end of which contains said support part (<NUM>) and a second end of which extends to a different side of the imaging station (<NUM>) than where said support part (<NUM>) is located, wherein the rear rest structure (<NUM>) has a mounting structure (<NUM>) which is arranged to enable adjustment of a mounting point of the rear rest structure (<NUM>) to the X-ray imaging apparatus (<NUM>), and wherein a distance of said support part (<NUM>) of the rear rest structure (<NUM>), from a mounting point of the rear rest structure (<NUM>) to the X-ray imaging apparatus, is arranged adjustable.