Patent Description:
Computed tomography (CT) is a kind of X-ray imaging in which a volume to be imaged is irradiated from different directions and, from the image information thus acquired, a desired two- or three-dimensional image can be reconstructed.

Traditional CT apparatus are large and massive, and they are typically mounted on a floor. A patient is positioned for imaging within an examination opening of the apparatus, typically on a horizontally extending and laterally movable examination platform.

Since development of cone beam computed tomography (CBCT) technology in which, for one, slower rotational speeds of the imaging means are used, apparatus of less weight than that of the more traditional CT apparatus have been developed. Among the CBCT apparatus, there are also e.g. ones which are not floor mounted but constructed to be mobile. Also, constructions comprising a vertically extending frame and a horizontally extending support for the imaging means have been designed.

Considering medical x-ray imaging apparatus in general, there are the kinds with no patient support construction in the apparatus itself at all, while those comprising a patient support construction are typically designed in view of imaging either a standing patient, a sitting patient or a lying patient.

An exemplary medical X-ray imaging apparatus of the prior art is disclosed by the document <CIT>.

The object of the invention and of its preferable embodiments is a CT apparatus, especially a CBCT apparatus, applicable for versatile use and enabling imaging various parts of an anatomy in various ways. The characteristic features of the invention are defined in claim <NUM>.

The invention is now described in more detail in reference to its preferable embodiments and the attached drawings, of which:.

<FIG> shows a schematic general side view of certain components of one embodiment, as an example, of a part of an apparatus according to the invention. The dental or medical CT imaging apparatus of <FIG> comprises an elongated frame part <NUM> extending in a first direction and having a first end and a second end. From this elongated frame part <NUM> extends in a second direction, which is substantially orthogonal to the first direction, a support construction <NUM> which supports an X-ray source <NUM> and an image detector <NUM> yet which as such are not visible in <FIG>. The X-ray source <NUM> and the image detector <NUM>, which together form X-ray imaging means <NUM>, <NUM>, may be mounted to the support construction <NUM> essentially opposite to each other yet in embodiments, their mutual position may also be arranged to be adjustable.

<FIG> further shows a patient support <NUM> which is a structure mechanically connected to the elongated frame part <NUM> and extending substantially in parallel with the elongated frame part <NUM>. In the embodiment of <FIG>, the patient support <NUM> is essentially of the same length as the elongated frame part <NUM>.

According to one aspect, for example, the length of the elongated frame part <NUM> is of the order of <NUM>.

According one aspect, for example, the length of the elongated frame part <NUM> is between <NUM> and <NUM>.

According one aspect, for example, the length of the patient support <NUM> is <NUM>-<NUM> % of the length of elongated frame part <NUM>.

According to one aspect, for example, the patient support <NUM> has a longer dimension in a first direction and a shorter dimension in a second direction orthogonal to the first direction.

According to one aspect, for example, the patient support <NUM> is at least in the first direction at least for its prevailing part radiolucent.

According to one aspect, for example, the radiolucent part of the patient support <NUM> is of essentially the same length as the elongated frame part <NUM>.

According to one aspect, for example, the patient support <NUM> comprises at least at either of its ends in the first direction a section which is not radiolucent.

According one aspect, for example, the length of the radiolucent part of the patient support <NUM> in the first direction is <NUM>-<NUM> % of the length of the elongated frame part <NUM>.

According to one aspect, for example, the support construction <NUM> supporting the X-ray imaging means <NUM>, <NUM> is a circular gantry having a central axis <NUM>. The gantry may partially encircle or completely house the X-ray imaging means <NUM>, <NUM>.

According to one aspect not directly visible in <FIG>, for example, the apparatus comprises a driving mechanism <NUM> arranged to drive the X-ray imaging means <NUM>, <NUM> about a rotation axis. This rotation axis may coincide with the central axis <NUM> of the support construction <NUM> in form of the gantry and it may be a physical axis, or a virtual rotation axis as in the case of <FIG>.

According to one aspect, for example, the central axis <NUM> of the gantry coincides the center of rotation / the rotation axis of the X-ray imaging means <NUM>, <NUM> when they are driven along a curved path.

According to one aspect, the rotation axis is an instantaneous (virtual) rotation axis and the location of the instantaneous rotation axis in relation to the central axis <NUM> can be arranged to be changed.

According to one aspect, at least either of the components the ray source <NUM> and the image detector <NUM> is arranged to be laterally movable from a location exactly opposite to the other component.

According to one aspect, the structure <NUM> supporting the X-ray imaging means <NUM>, <NUM> comprises a gantry having a central axis and the structures of apparatus allows for at least either of: laterally moving the X-ray source <NUM> between positions at which a central ray it generates coincides with the central axis of the gantry and a position at which the central ray it generates does not coincide with the central axis of the gantry; laterally moving the image detector <NUM> between positions at which a vector which is normal to the detector surface at the center of the image detector <NUM> coincides the central axis of the gantry and a position at which the vector which is normal to the detector surface at the center of the image detector <NUM> does not coincide the central axis of the gantry. The lateral moving of the X-ray imaging means <NUM>, <NUM> may include moving the X-ray imaging means <NUM>, <NUM> to a position at which they face each other while the central ray the X-ray source <NUM> generates does not coincide the central axis of the gantry and the vector which is normal to the detector surface at the center of the image detector <NUM> does not coincide the central axis of the gantry.

According to another aspect, another driving mechanism <NUM> is arranged to the apparatus to enable moving the support construction <NUM> back and forth in a direction which is substantially parallel with the direction in which the elongated frame part <NUM> extends. According to one aspect, that driving mechanism <NUM> may be arranged to move the support construction <NUM> along or alongside the elongated frame part <NUM>.

In the example according to <FIG>, the driving mechanism <NUM> of the support construction <NUM> discussed above comprises a motor <NUM> and a gearing <NUM> arranged to rotate a pulley <NUM>. In the construction shown as one embodiment in <FIG>, while the motor <NUM> and the pulley <NUM> are located at the proximity of the second end of the elongated frame part <NUM> there is also another pulley <NUM>' at the proximity of the first end of the elongated frame part <NUM> and around the pulleys <NUM>, <NUM>' goes a belt <NUM>, or a correspondingly functioning component like a chain. This mechanism is then functionally connected to the support construction <NUM> to drive it along the elongated frame part <NUM>, such as shown as an example in <FIG> where grooves <NUM> are arranged to the elongated frame part <NUM> and, to the support construction <NUM>, projecting parts <NUM> which are fitted to slide along the grooves <NUM>. In an embodiment, to minimize friction, roller type linear guide ways are used in which case the motion is rather rolling than sliding.

According to one aspect not shown in any of the Figs, for example, the driving mechanism to drive the support construction <NUM> comprises a motor arranged to the support construction <NUM> itself.

Regardless of the details of the construction of the driving mechanism <NUM> to drive the support construction <NUM> along or alongside the elongated frame part <NUM>, in one embodiment the construction of the apparatus allows for driving the support construction <NUM> essentially the whole length between the first and second ends of the elongated frame part <NUM>.

According to yet another aspect and as shown is <FIG>, the apparatus comprises a connection construction <NUM>, <NUM> which connects the patient support <NUM> to the elongated frame part <NUM>.

According to another aspect, an example of which is shown is <FIG>, the apparatus comprises a connection construction <NUM>, <NUM> which mechanically connects the patient support <NUM> to the elongated frame part <NUM>.

The connection construction <NUM>, <NUM> may comprise a patient support adjustment mechanism <NUM>', <NUM>' configured to enable displacing the patient support <NUM> closer and further away from the elongated frame part <NUM>.

According to another aspect, a driving mechanism <NUM>'', <NUM>'' is arranged in functional connection with the patient support adjustment mechanism <NUM>', <NUM>'.

According to another aspect, the patient support adjustment mechanism <NUM>', <NUM>' may comprise a first adjustment mechanism <NUM>' arranged together with its driving mechanism <NUM>'' comprised in the driving mechanism <NUM>", <NUM>" substantially at the first end of the elongated frame part <NUM>, and a second adjustment mechanism <NUM>' arranged together with its driving mechanism <NUM>" comprised in the driving mechanism <NUM>", <NUM>" substantially at the second end of the elongated frame part <NUM>.

According to one aspect, for example, the patient support adjustment mechanisms <NUM>', <NUM>' is arranged in functional connection with the control system of the apparatus and the control system is configured to control the driving mechanism <NUM>", <NUM>" of the adjustment mechanism <NUM>', <NUM>'.

According to one aspect, for example, the control system is configured to control the connection construction <NUM>, <NUM> comprising the first adjustment mechanism <NUM>' with its driving mechanism <NUM>", arranged substantially at the first end of the elongated frame part <NUM>, and the second adjustment mechanism <NUM>' with its driving mechanism <NUM>'', arranged substantially at the second end of the elongated frame part <NUM>, to keep at the first and second ends of the elongated frame part <NUM> an identical distance between the elongated frame part <NUM> and the patient support <NUM> when adjusting the distance between the two.

According to another aspect, the distance between the ends of the elongated frame part <NUM> and the patient support <NUM> can be adjusted to be different. According to one aspect, the first and second adjustment mechanisms <NUM>', <NUM>' are arranged to be controlled independently.

According to one aspect, as shown in <FIG>, considering the above-discussed first direction of the patient support construction <NUM>, its cross section as for its prevailing part is curved so as to better support a patient against the concave surface of the patient support construction <NUM>.

According to one other aspect, as shown in <FIG>, at the edges <NUM> of that cross section of the patient support construction <NUM> the shape of the cross section turns into being curved in the opposite direction.

According to one other aspect and as further shown in <FIG>, near the edges of the above-discussed cross section of the patient support construction <NUM> and on the side opposite to the for its prevailing part concave surface is arranged a holding structure <NUM>. The holding structure <NUM> may be e.g. an elongated handle or an attachment structure to receive a strap designed to extent on or over the concave side of the patient support construction <NUM>, to be used to provide further support to the patient and thus to help keeping still during an imaging exposure.

Turning to <FIG> which shows, as a schematic general side view, certain components of an embodiment, as an example, of an apparatus according to the invention in which, in addition to what can be referred to as a first elongated frame part <NUM> discussed above, there is a second elongated frame part <NUM> mechanically connected to the first elongated frame part <NUM> of essentially the same length as the first elongated frame part <NUM>.

According to one aspect and still referring to <FIG>, at the proximity of the first end of the first elongated frame parts <NUM>, <NUM> is arranged an articulated connection construction <NUM> to mechanically connect the first and second elongated frame parts <NUM>, <NUM>, to allow for tilting of the first elongated frame part <NUM> about at least one tilt axis in relation to the second elongated frame part <NUM>. The at least one tilt axis is orthogonal to both the abovementioned first and second directions in which the elongated frame part <NUM> and the support construction <NUM> extend. Or, in other words, the tilt axis may be an axis which is orthogonal to the direction in which the first and second elongated frame parts <NUM>, <NUM> extend as well as to direction in which the support construction <NUM> for the X-ray imaging assembly <NUM>, <NUM> extends - perpendicularly from the first longitudinally extending frame part <NUM>.

In the embodiments shown in the Figs. and discussed in more detail in this application, the at least one tilt axis is horizontal. This is not to be understood that the tilt axis needs to be horizontal.

According to another aspect, on the side of the second elongated frame part <NUM>, a mounting structure <NUM> not directly visible in <FIG> is arranged in connection with the articulated connection construction <NUM>. The mounting structure <NUM> is arranged movable along or alongside the second elongated frame part <NUM>.

According to another aspect, for example, at the proximity of the second end of the second elongated frame part <NUM> is arranged a locking mechanism <NUM> configured to enable connecting and disconnecting the first and second elongated frame parts <NUM>, <NUM>. Particularly, a locking mechanism <NUM> may be arranged at the proximity of the second end of the first and second elongated frame parts <NUM>, <NUM>, the locking mechanism being configured to enable connecting together and disconnecting the first and second elongated frame parts <NUM>, <NUM> at the proximity of the second ends of the first and second elongated frame parts <NUM>, <NUM>.

When the second elongated frame part <NUM> is mounted stable and the locking mechanism <NUM> is not connecting the first and second elongated frame parts <NUM>, <NUM>, the second end of the first elongated frame part <NUM> is free to move laterally while the articulated connection <NUM> between the frame parts <NUM>, <NUM> allows for turning of the first elongated frame part <NUM> about the horizontal tilt axis at the proximity of the first end of the first elongated frame part <NUM>. In case of a vertical starting position, such movably arranged mounting structure as discussed above allows for descending and ascending of the first end of the first elongated frame part <NUM>.

<FIG> shows the apparatus according to <FIG> at a stage where the first end of the first elongated frame part <NUM> has moved downwards and the second end of the first elongated frame part <NUM> has moved horizontally on a surface. The apparatus may be configured to allow for descending of the first end of the first elongated frame part <NUM> all the way to the proximity of the second end of the second elongated frame part <NUM>.

According to yet another aspect, not directly visible in <FIG> and <FIG>, in functional connection with the second elongated frame part <NUM> is arranged a driving mechanism <NUM> to drive the mounting structure <NUM> along or alongside the second elongated frame part <NUM>. When being in mechanical connection with the first elongated frame part <NUM>, at the proximity of the first end of it, the driving mechanism <NUM> can move the first end of the first elongated frame part <NUM> in a direction in which the second elongated frame part <NUM> extends.

The driving mechanism <NUM> to drive the mounting structure <NUM> may be a construction similar with the driving mechanism <NUM> driving the support construction <NUM> of the X-ray imaging means <NUM>, <NUM> along or alongside the first elongated frame part <NUM>.

According to one aspect, the driving mechanism <NUM> to drive the mounting structure <NUM> comprises a chain drive.

To describe some of the features discussed above in other words, in an embodiment in mechanical connection with the articulated connection construction <NUM>, on the side of the second elongated frame part <NUM>, is arranged a mounting structure <NUM> which is arranged movable along or alongside the second elongated frame part <NUM>, such construction thereby providing a degree of freedom of movement along or alongside the second frame part <NUM> for the articulated connection construction <NUM> and for the first end of the first elongated frame part <NUM> mechanically connected to the articulated connection construction <NUM>.

In an embodiment, the mounting structure <NUM> is arranged movable along or alongside the second elongated frame part <NUM> at least essentially a distance corresponding to the length of the first elongated frame part11, and the articulated connection construction <NUM> is arranged to allow for tilting of the first elongated frame part <NUM> between orientations at which the first and second elongated frame parts <NUM>, <NUM> extend essentially in parallel and at which the first and second elongated frame parts <NUM>, <NUM> extend essential orthogonally.

According to yet another aspect, the locking mechanism <NUM> comprises a displacement mechanism <NUM> which is not directly visible in Figs. discussed so far to move the second end of the first elongated frame part <NUM> a distance away from the second elongated frame part <NUM> when the locking mechanism <NUM> disconnects the first and second elongated frame parts <NUM>, <NUM>.

According to one aspect not shown in detail in the Figs. discussed so far, the locking mechanism <NUM> comprises a motor driven arrangement with mating components on the side of a motorized structure and the first elongated frame part <NUM>, respectively.

The locking mechanism <NUM> may further comprise a guiding construction configured to guide the second end of the first elongated frame part <NUM> straight on the locking mechanism <NUM> when the second end of the first elongated frame part <NUM> is moving towards the locking mechanism <NUM>. Or, to put it in other words, when the second end of the first elongated frame part <NUM> moves towards and approaches the second end of the second elongated frame part <NUM>.

According to yet another aspect and, as shown as an example in <FIG> and <FIG>, the first elongated frame part <NUM> comprises at the proximity of its second end at least one wheel or roller <NUM>.

According to another aspect, instead of the wheel or roller, a structure designed to slide on a surface may be arranged at the second end of the first elongated frame part <NUM>.

A more detailed embodiment concerning some of the features discussed above is presented in <FIG>, which overall shows the second ends of the first and second elongated frame parts <NUM>, <NUM> yet wherein the very end of the second end of the first elongated frame parts <NUM> is cut, partly completely cut and partly just one wall being cut so that what could be called a back wall <NUM>' is still visible.

The embodiment shown in <FIG> includes a structure in which the displacement mechanism <NUM> comprises two toothed bars <NUM> mounted at the proximity of the second end of the second elongated frame part <NUM>, to extent essentially orthogonally to the direction at which the second elongated frame part <NUM> extends, and two toothed wheels <NUM> mounted at the proximity of the second end of the first elongated frame part <NUM>. The toothed wheels <NUM> are configured compatible with the toothed bars <NUM>. While two toothed bars and wheels are shown, the number of those could be just one, or more than two.

The embodiment shown in <FIG> further includes the displacement mechanism <NUM> comprising a displacing motor <NUM> arranged in functional connection with toothed wheels <NUM>.

According to one embodiment, to operate the displacement mechanism <NUM>, the control system of the apparatus may be configured to, when the first and second elongated frame parts <NUM>, <NUM> extend essentially in parallel and as a response to a control signal to alter the mutual orientation of the first and second elongated frame parts <NUM>, <NUM>, first operate the displacement mechanism <NUM> to move the second end of the first elongated frame part <NUM> a distance away from the second end of the second elongated frame part <NUM> and, second, operate said third driving mechanism <NUM> to drive the mounting structure <NUM> along or alongside the second elongated frame part <NUM> towards the second end of the second elongated frame part <NUM>, so as to move the second end of the first elongated frame part <NUM> a further distance away from the second end of the second elongated frame part <NUM>.

The locking mechanism <NUM> shown in <FIG> further comprises a sensing element <NUM> configured to detect when the second end of the first elongated frame part <NUM>, when moving towards the second end of the second elongated frame part <NUM>, has reached a predefined locking position.

The locking mechanism <NUM> shown in <FIG> further comprises a locking actuator <NUM> and the control system of the apparatus may be configured to, as a response to a control signal from the sensing element <NUM> that the second end of the first elongated frame part <NUM> when moving towards the second end of the second elongated frame part <NUM> has reached a predefined locking position, send a control signal to the locking actuator <NUM> to lock the second end of the first elongated frame part <NUM> at said predefined locking position.

In one embodiment, instead or in addition to having a construction which actively moves the second end of the first elongated frame part <NUM> a distance away from the second end of the second elongated frame part <NUM>, when the first and second elongated frame parts <NUM>, <NUM> have been disconnected by the locking mechanism <NUM>, the locking mechanism <NUM> comprises a displacement mechanism <NUM> configured to merely ease moving of the second end of the first elongated frame part <NUM> a distance away from the second end of the second elongated frame part <NUM>. In such case, the displacement mechanism may be or includes e.g. a ramp sloping away from the second end of the second elongated frame part <NUM>.

The guiding construction according the embodiment of <FIG> comprises two guide rails <NUM> mounted from their first end at the proximity of the second end of the second elongated frame part <NUM> and extending essentially orthogonally to the direction at which the second elongated frame part <NUM> extends, to form two guide passages. While two guide rails <NUM> are shown in <FIG>, the number of rails could be something else as well - yet, using just one rail it may be difficult to form a passage truly having a guiding function.

While shown in <FIG> is the first elongated frame part <NUM> to comprise at the proximity of its second end two wheels, or rollers <NUM>, at a first distance from each other, and the guiding construction to comprise two guide rails <NUM> to form two guide passages essentially at the same first distance from each other, the guide rails <NUM> further comprise at their second ends a beveling so as to make a distance between the guide passages smaller at that end of the passages than the first distance. Such construction aids in guiding the second end of the first elongated frame part <NUM> to find a designed passage to move towards the second elongated frame part <NUM>.

According to one aspect, for example and as shown in <FIG>, support construction <NUM> for the imaging means <NUM>, <NUM> in a form of a gantry basically does not completely encircle the imaging means <NUM>, <NUM> but functions primarily or solely as a support structure for holding the imaging means <NUM>, <NUM>, and structures arranged to the gantry to drive the imaging means <NUM>, <NUM> about an axis. This kind of solution enables realizing the gantry as less heavy and as providing better access to the volume between the imaging means <NUM>, <NUM>, both physically and considering an area from where one may have a clear line of sight at that volume.

<FIG> shows as a block diagram an example of components of a control system applicable for use in an apparatus according to this disclosure. In various embodiments, not all those features are necessarily present in a control system of the apparatus. The control system according to <FIG> is configured to enable controlling, first of all, operation of the X-ray source and the image detector. Components controlling operation of the X-ray source and the image detector can include components physically arranged to the Xx-ray source and/or the image detector and/or elsewhere in the apparatus.

Claim 1:
A dental or medical CT imaging apparatus, comprising:
- a first elongated frame part (<NUM>) extending in a first direction and comprising a first end and a second end;
- a support construction (<NUM>) extending from the first elongated frame part (<NUM>) in a second direction substantially orthogonal to the first direction;
- an X-ray source (<NUM>) and an image detector (<NUM>) mounted to the support construction (<NUM>) which together form an X-ray imaging means (<NUM>, <NUM>) ;
- a first driving mechanism (<NUM>) arranged to move the imaging means (<NUM>, <NUM>) about an axis (<NUM>);
- a second driving mechanism (<NUM>) arranged to move the support construction (<NUM>) in a direction substantially parallel with the first direction in which the first elongated frame part (<NUM>) extends;
- a patient support (<NUM>);
- a control system;
characterized in that the apparatus comprises a second elongated frame part (<NUM>) comprising a first end and a second end, wherein at the proximity of the first end of the first elongated frame part (<NUM>) is arranged an articulated connection construction (<NUM>) to mechanically connect the first and second elongated frame parts (<NUM>, <NUM>), to allow for tilting of the first elongated frame part (<NUM>) about at least one tilt axis in relation to the second elongated frame part (<NUM>), the at least one tilt axis being orthogonal to both said first and second directions, and wherein at the proximity of the second end of the first and second elongated frame parts (<NUM>, <NUM>) is arranged a locking mechanism (<NUM>) configured to enable connecting together and disconnecting the first and second elongated frame parts (<NUM>, <NUM>) at the proximity of the second ends of the first and second elongated frame parts (<NUM>, <NUM>).