Patent Description:
Systems that utilize high energy radiation, for example X-ray radiation, to examine the internal structure of an object are known. These systems may be used to produce images of body parts. Detection systems, particularly those used in medical applications, direct X-rays through the body part of interest toward an X-ray detector. In certain kinds of X-ray imaging, the image is captured during a process in which the X-ray generator and the imaging device move around the patient's head according to a predetermined geometric path and speed profile. The movement of the X-ray generator and the imaging device is traditionally synchronized so that the imaging device surface is perpendicular to the layer-of-interest. In other kinds of X-ray imaging, the X-ray generator and the imaging device are aligned in a predetermined manner.

X-ray imaging systems of the prior art are disclosed in published applications <CIT> and <CIT>.

One object of the invention is to provide a mechanism for calibrating an imaging system, for example, provide a mechanism for calibrating the imaging system for use with a patient support by determining a position of the patient support relative to a known coordinate system of the x-ray imaging system. The techniques and systems described may be used in combination imaging systems, for example, a combination of Panoramic, Cephalometric, and/or Computed Tomography imaging modalities.

Techniques and systems described help reduce drawbacks of Panoramic/Cephalometric/Computed Tomography (CT) combination imaging systems related to the calibration of critical components associated with the imaging systems. When, for example, an imaging system is modified or supplemented to allow for multiple types of images (for example, Panoramic, Cephalometric, and/or Computed Tomography (CT) images), the X-ray imaging system needs to be calibrated accurately in order to, for example, ensure accurate imaging and prevent multiple retakes of the images thereby preventing the patient from repeated X-rays and unnecessary exposure to X-ray radiation.

In some instances, Cephalometric imaging components are provided as an add-on or accessory to systems that are designed for Panoramic imaging. Systems and methods described herein provide for the calibration of an imaging system capable of capturing Panoramic, Cephalometric, and/or Computed Tomography (CT) images of the patient. In some, but not all, systems there is a first X-ray source used for Panoramic and Computed Tomography imaging and a second X-ray source used for Cephalometric imaging. Systems and methods described herein provide, among other things, for determining positions of add-on or accessory components relative to original or previously calibrated components of the imaging system by determining positions and/or orientations of one or more components relative to a coordinate frame of the imaging system.

Embodiments of the invention are defined in the independent and dependent claims. The features recited in the dependent claims are mutually freely combinable unless otherwise explicitly stated.

One x-ray imaging system includes a column, an upper shelf coupled to the column, and a rotating part coupled to the upper shelf. The x-ray imaging system is configured to controllably pivot the upper shelf relative to the column (e.g., a pivoting movement). Additionally, the x-ray imaging system is configured to controllably rotate the rotating part relative to the upper shelf and to provide a controllable linear movement of the rotating part along a length of the upper shelf in a direction radial to the column.

One X-ray imaging system for medical imaging includes a column. The X-ray imaging system also includes an upper shelf coupled to the column. The X-ray imaging system includes a rotating part rotatably coupled to the upper shelf and having a rotation axis with respect to the upper shelf. The rotating part includes an X-ray source. The rotating part or another component of the X-ray imaging system includes a source of visible light, for example, a laser, an LED, or other light source, and an X-ray imaging detector. The X-ray source and the X-ray imaging detector are configured to provide an image by means of at least a rotational movement (R) of the rotating part. The X-ray imaging system also includes a Cephalometric patient support configured to support a patient to be imaged. The Cephalometric patient support can be selectively attached to the column by a first arm, and includes a pair of adjustable ear rods, wherein each of the ear rods has an ear bud. The light source is configured to generate and project a beam of light to a fixed location on the X-ray imaging detector. In one example, the fixed location is associated with a Frankfurt plane of the patient. The Cephalometric patient support is adjustable to align the ear buds with the beam of light.

One method of operating an imaging system performs Cephalometric imaging. The imaging system includes a column, an upper shelf coupled to the column, a rotating part coupled to the upper shelf and linearly translatable along a length of the upper shelf in a direction radial to the column, a first x-ray source coupled to the rotating part, and an x-ray detector coupled to the rotating part on an opposite side of a first imaging volume from the first x-ray source. At least one calibration sweep is performed by controllably adjusting a position of the x-ray detector relative to the Cephalometric patient support. Image data is captured by the x-ray detector while performing the at least one calibration sweep. A center position of the Cephalometric patient support is determined relative to the imaging system in at least two dimensions based on the image data captured while performing the at least one calibration sweep.

One imaging system includes a column, an upper shelf coupled to the column, a rotating part coupled to the upper shelf and linearly translatable along a length of the upper shelf in a direction radial to the column, a first x-ray source coupled to the rotating part, an x-ray detector coupled to the rotating part on an opposite side of the first imaging volume from the first x-ray source, and a controller. The controller is configured to perform at least one calibration sweep by controllably adjusting a position of the x-ray detector relative to the Cephalometric patient support. Image data is captured by the x-ray detector while performing the at least one calibration sweep. The controller then determines a center position of the Cephalometric patient support relative to the imaging system in at least two dimension based on the image data captured while performing the at least one calibration sweep.

One imaging system also includes a Cephalometric patient support arm that is selectively couplable to the column. The Cephalometric patient support is coupled to a distal end of the Cephalometric patient support arm and the imaging system determines an unknown position of the Cephalometric patient support and uses that determined position information to perform Cephalometric imaging.

One imaging system also includes a Cephalometric x-ray source arm that is also selectively couplable to the column. A second x-ray source is coupled to the distal end of the Cephalometric x-ray source arm and further calibration is performed by the imaging system to determine a middle angle of the second x-ray source relative to the Cephalometric patient support. Cephalometric imaging is performed by emitting x-rays from the second x-ray source towards the Cephalometric patient support and capturing image data using the x-ray detector.

The term "medical imaging" refers to, for example, dental, extra-oral, oral, maxillofacial, carpus, or ears, nose, and throat imaging.

The definitions of the below-defined verbs and terms shall be applied, unless a different definition is given in the claims or elsewhere in this description/specification.

The verb "comprise" is used in this document as an open limitation that neither excludes nor requires the existence of un-recited features. The verbs "include" and "have/has" are defined as in the same manner as the verb comprise.

The terms "a", "an" and "at least one", as used herein, are defined as one or more than one and the term "plurality" is defined as two or more than two. The term "another", as used herein, is defined as at least a second or more.

The term "or" is generally employed in its sense comprising "and/or" unless the content clearly dictates otherwise.

One or more embodiments are described and illustrated in the following description and accompanying drawings. These embodiments are not limited to the specific details provided herein and may be modified in various ways. Furthermore, other embodiments may exist that are not described herein. Also, the functionality described herein as being performed by one component may be performed by multiple components in a distributed manner. Likewise, functionality performed by multiple components may be consolidated and performed by a single component. Similarly, a component described as performing particular functionality may also perform additional functionality not described herein. For example, a device or structure that is "configured" in a certain way is configured in at least that way, but may also be configured in ways that are not listed.

<FIG> illustrates main parts of an X-ray imaging system <NUM>, which can be used in medical imaging, for example, in extra-oral dental imaging.

The system <NUM> includes a rotating part (gantry) <NUM>, which includes a first X-ray source <NUM>. An X-ray imaging detector unit <NUM> is also attached to the rotating part <NUM>. As discussed in further detail below, the X-ray imaging detector unit <NUM> includes, for example, one or more x-ray detectors for capturing image data relating to x-rays emitted, for example, by the first X-ray source <NUM>. In some implementations, a position of the X-ray imaging detector unit <NUM> is adjustable relative to the rotating part, for example, the X-ray imaging detector unit <NUM> is rotatable or movable in a linear fashion. In other examples, one or more individual x-ray detectors included in the X-ray imaging detector unit <NUM> may be moveable. The X-ray source <NUM> and/or the X-ray imaging detector unit <NUM> provides, for example, a Panoramic, CT, or Cephalometric image by means of at least a rotational movement R around a rotation axis <NUM> of the rotating part <NUM>. The R-movement of the rotating part <NUM> is, for example, up to <NUM> degrees around the rotation axis <NUM>. In the example illustrated, the first X-ray source <NUM> is positioned within a housing H. In some implementations, the housing H also includes a light source <NUM> (for example, a laser or LED) that can be utilized for determining alignment of various components.

The system <NUM> also includes a second X-ray source <NUM> which may be attached to a column <NUM> by a second arm <NUM>. The second X-ray source <NUM> includes an X-ray beam limiting device <NUM>. Although described as two separate arms, the first arm <NUM> and the second arm <NUM> may be mechanically linked so as to operate in effect as a single arm. The single arm may be pivotally connected to the column <NUM> so that raising one end of the single arm causes the other end of the single arm to lower (for example, in a manner similar to a seesaw or teeter-totter).

The rotating part <NUM> includes a rotating motor, which is configured to rotate the rotating part <NUM> by means of rotation means (not shown). Alternatively, the rotating motor can be situated in an upper shelf <NUM> of the system <NUM>. In one example, the rotating part <NUM> is attached to the upper shelf <NUM>.

The rotating part <NUM> has, for example, a form approximating a letter C and the X-ray source <NUM> is on one end of the rotating part <NUM>. The X-ray source <NUM> may be common for two imaging modes-- Panoramic imaging and CT imaging (e.g., CBCT imaging, where an X-ray beam is a cone-shaped beam). However, in some embodiments, the x-ray system <NUM> might be configured to perform only one type of imaging (e.g., only CT imaging or only panoramic imaging) using the x-ray source <NUM>. In some CT imaging techniques, the X-ray beam is one of a pyramidal-shaped beam, half-moon-shaped cone beam, or other shaped beam.

In the example provided, the X-ray source <NUM> also includes a beam limiting device <NUM> for the X-ray source <NUM> and an X-ray beam limiting motor configured to adjust the X-ray beam limiting device <NUM>, for example, in a horizontal direction (CH) and a vertical direction (CV). During imaging, the X-ray beam limiting device <NUM> controls the size and shape of the X-ray beam so that it matches the needs of a selected imaging protocol, a selected image size, and the related detector size.

On the other end of the rotating part <NUM> is the X-ray imaging detector unit <NUM>, which can include, for example, one or two X-ray detectors 227a, 227b (see <FIG>). An example embodiment of a one-detector X-ray imaging detector unit <NUM> can include one X-ray detector <NUM> which may include one Panoramic detector, one Cephalometric detector, which also enables Panoramic imaging, one Panoramic/CT combination detector, one Panoramic/CT/Cephalometric combination detector, or one detector configured to be used in Panoramic/CT imaging and in one-shot Cephalometric imaging.

The one-detector X-ray imaging detector unit <NUM> can be adjustable, for example, by rotating the X-ray imaging detector unit <NUM> relative to the rotating part <NUM> so that one detector of the X-ray imaging detector unit <NUM> can be positioned preferably perpendicularly to the used X-ray source <NUM> or <NUM> (described in further detail herein) and/or by moving one detector of the X-ray imaging detector unit <NUM> in a linear fashion relative to the rotating part <NUM> for adjusting a distance between the one detector or X-ray imaging detector unit <NUM> and the X-ray source <NUM> in Panoramic/CT imaging.

In an example of a two-detector X-ray detector unit <NUM>, the detector unit <NUM> can include one Panoramic detector and one CT detector, or one Cephalometric detector, which also enables Panoramic imaging. In a two-detector embodiment of the detector unit <NUM>, the detectors are arranged, for example, successively in Panoramic imaging, whereupon the Panoramic or Cephalometric detector is arranged as a front detector for arranging magnification ratio for the imaging mode, and the CT detector as a rear detector. The swap of the detectors 227a, 227b (see <FIG>) is arranged so that the front detector 227a moves aside by means of moving means <NUM>, for example, a rail 231a, 231b and a rotator configured to move along the rail 231a, 231b and to rotate so that the front detector 227a slides, for example, next to a rear detector 227b, when it is necessary to use the rear detector 227a in CT imaging or the front detector 227a in Cephalometric imaging. Alternatively, the front detector 227a can be moved to another position relative to the rear detector 227b in Cephalometric imaging. The place of the front detector 227a in Cephalometric imaging may depend upon on how the front detector 227a is displaced by means of the swap movement, and the R- and L-movements relative to the X-ray source <NUM> that is used. The Cephalometric detector 227a can be positioned preferably perpendicularly to the used X-ray source <NUM>. The front detector 227a returns similarly by sliding, when it is necessary to move the front detector 227a back to the front position.

The rotating part <NUM> can include a detector motor <NUM> configured to move at least one detector by means of the moving means <NUM>, if the detector unit <NUM> includes separate detectors 227a, 227b for the Panoramic and CT imaging.

The system <NUM> includes the column <NUM> for adapting a height Z of the system <NUM>-and the rotating part <NUM>. The column <NUM> includes height adapting means <NUM> which may include, for example, a height motor, a gear, and a threaded rod, and telescopic or counter weighted means configured to be driven by the height motor, for providing an up/down movement Z to adapt the height of the rotating part <NUM> to the height of the patient <NUM> for the Panoramic, Cephalometric, or CT imaging modes. The height adapting means <NUM> can realize the Z-movement, for example, as a movement of the height adapting means and/or as a telescopic or counterweighted movement.

A lower shelf or second patient support <NUM> is attached to the column <NUM>. The lower shelf or second patient support <NUM> is used for positioning a patient <NUM> for imaging, for example, Panoramic and/or CT imaging and for supporting the patient <NUM>, for example, from a tip of the patient's <NUM> chin by a chin support CS during the imaging. In some cases, the system <NUM> may only include one patient support, for example, the lower shelf or second patient support <NUM>.

Alternatively, when the system <NUM> includes a seated patient's <NUM> positioning system (not shown), the Z-movement is realized, for example, by adapting in the Z-direction the height of at least one of the following: a chair, the lower shelf <NUM>, and the column <NUM>.

The lower shelf <NUM> can also include a head support (not shown), which supports, for example, the patient's <NUM> forehead and/or temple in the Panoramic/CT imaging position.

The system <NUM> includes the upper shelf <NUM>, which supports the rotating part <NUM>. In one example, the upper shelf <NUM> is attached to an upper end of the column <NUM> with a pivoting joint (means) <NUM>, which enables a pivot movement P of the upper shelf <NUM> around the column <NUM> and in respect to a lower shelf <NUM> so that the rotating part <NUM> is over, for example, the lower shelf <NUM>.

The upper shelf <NUM> includes pivot movement means <NUM>, which includes, for example, a pivot motor <NUM> configured to pivot the upper shelf <NUM> around the column <NUM> by means of the pivoting joint <NUM>.

The upper shelf <NUM> includes linear movement means <NUM>, for example, a linear conveyor configured to support the rotation means of the rotating part <NUM> and to enable the rotating part <NUM> to rotate around the rotation axis <NUM>, at least one rail and/or track configured to guide the linear conveyor in the upper shelf <NUM>, and a linear motor configured to drive the linear conveyor along the at least one rail and the upper shelf <NUM>, which enable the rotating part <NUM> and the rotation means to move with respect to the upper shelf <NUM> by means of a linear movement L. The linear movement means <NUM> of the upper shelf <NUM> can be provided so that L movement in a plane of the upper shelf <NUM> is a direct linear movement, for example, it is parallel to the upper shelf <NUM> or it is in a certain angle with respect to the parallel direction, or the L-movement in the plane of the upper shelf <NUM> is a non-direct linear movement having for example a curved path or a devious path.

The rotation means attach the rotating part <NUM> to the upper shelf <NUM>. The rotation means are able to move with at least one L-movement so that the axis <NUM> and, thus, the rotation center in respect to the upper shelf <NUM> can be adjusted along the L-movement. Thus, the axis <NUM> can be positioned within a plane defined by the P-movement of the upper shelf <NUM> and the L-movement of the rotating part <NUM> during the imaging. By using a rotating P-movement, rather than a linear X-movement, to adjust the lateral position of the rotating part <NUM>, it is possible to design a lighter and thinner upper shelf <NUM>, thus giving the system <NUM> a smaller footprint.

In addition, the system <NUM> may include on one side of the column <NUM> a first Cephalometric arm <NUM> that has a certain first length. The arm <NUM> attaches a Cephalometric patient support <NUM> to the system <NUM> at a certain first distance that corresponds with the first length from the column <NUM>. However, in other embodiments, the system <NUM> might not include a first Cephalometric arm <NUM> and, instead, provides a Cephalometric patent support positioned by other mechanism (e.g., fixedly coupled to the column without the use of an arm).

The Cephalometric patient support <NUM>, which has a significantly simpler structure than in traditional Cephalometric units, includes Cephalometric patient support means <NUM>, <NUM>, for example, two adjustable ear rods <NUM> and an adjustable nasion support <NUM>, for supporting the patient <NUM> to be imaged. The patient's head is supported, for example from an outer part of the ear canal with the ear buds 268A (shown in <FIG>) included in the ear rods <NUM> and from the nasion support <NUM> placed in contact with the top of the nasal bridge. The adjustable ear rods <NUM> and adjustable nasion support <NUM> is attached to the Cephalometric patient support <NUM> in a manner that enables them to rotate, for example, two main imaging positions: lateral and PA projections. The lateral projection is basically a side view and the PA projection is from back to front view of a skull of the patient.

The ear rods <NUM> can be tiltable or rotatable ear rods having a down position, where the ear rods <NUM> support the patient <NUM>, and an up position, where it is possible to place the patient in the Cephalometric imaging position or where the patient can depart from the Cephalometric imaging position, when the tilted or rotated ear rods <NUM> in the up position provide a clear passage of the patient. Although the example of <FIG> includes a Cephalometric patient support <NUM> for positioning the head of a patient for Cephalometric imaging, other implementations may include other types of patient support for other types of imaging. For example, the system <NUM> may be configured to include a patient hand support for positioning the hand of a patient for carpus imaging.

In addition, the system <NUM> may include on other side of the column <NUM> a second Cephalometric arm <NUM> that has a certain second length. Attached to the second Cephalometric arm <NUM> is a second X-ray source <NUM>, which is used in Cephalometric imaging. The second Cephalometric arm holds the second x-ray source at a second distance from the system <NUM>, corresponding to a second length from the column <NUM>. The X-ray source <NUM> includes an X-ray beam limiting device <NUM> for the Cephalometric imaging. Optionally, the X-ray beam limiting device <NUM> can be attached to the X-ray source <NUM>. The X-ray source <NUM> can be configured to rotate around a rotation axis <NUM> by means of rotation means 264A configured to perform a scanning movement S. The axis <NUM> of the X-ray source <NUM> is in line with a focal spot of the X-ray source <NUM> so that it passes through the focal spot. The arm <NUM> or the X-ray source <NUM> includes a rotating motor, which is configured to rotate the X-ray source <NUM> around the axis <NUM>, which coincides with the focal spot of the X-ray source <NUM>.

As noted, in some embodiments, the arms <NUM>, <NUM> can be separate arms attached to the column <NUM>, or it is possible to use one arm <NUM>, <NUM>, which includes the Cephalometric head <NUM> in its one end and the X-ray source <NUM> with the X-ray beam limiting device <NUM> in the other end of the single arm <NUM>, <NUM>.

In addition, the rotating part <NUM> can include a Cephalometric (secondary) collimator <NUM>, which is used in the Cephalometric imaging together with one detector of the detector unit <NUM>. The Cephalometric collimator <NUM> is attached, for example, to one (right) side of the rotating part <NUM> (for example, X-ray source <NUM>), as depicted in <FIG>. Alternatively, the Cephalometric collimator can be attached, for example, to another (left) side of the rotating part <NUM> (for example, X-ray source <NUM>).

In addition, the rotating part <NUM> can include a detector motor <NUM> configured to rotate at least one detector of the detector unit <NUM> for the Cephalometric imaging, and a collimator motor configured to adjust a position (height) of the Cephalometric collimator <NUM> in the Z-direction and/or a position of the collimator of the X-ray source <NUM>. Alternatively, or in addition, the X-ray beam limiting motor or the collimator motor can be configured to adjust both the X-ray beam limiting device <NUM> and the Cephalometric collimator <NUM>.

The rotating part <NUM> is driven over the Cephalometric patient support <NUM>, for example, with the P-, R-, and L-movements, so that the detector unit <NUM> and the Cephalometric collimator <NUM> are positioned for Cephalometric imaging.

The X-ray source <NUM> can be configured to provide, together with, for example, the detector unit <NUM> (for example, the Cephalometric detector 227a attached to the detector unit <NUM>) and the Cephalometric collimator <NUM> in the rotating part <NUM>, a Cephalometric image from the positioned patient <NUM>, when it is rotated around the axis <NUM> by means of the S-movement, and the detector unit <NUM> and the Cephalometric collimator <NUM> are arranged to move, for example, by means of at least one of the P-, R-, and L-movements of the rotating part <NUM>. Alternatively, the scanning movement of the X-ray beam--for example, a linear S-movement can be performed by moving the X-ray beam limiting device <NUM> of the X-ray source <NUM>.

If the one-shot detector is used, the detector unit <NUM> and the Cephalometric collimator <NUM> are positioned by means of at least one of the P-, R-, and L-movements, but the image can be taken without these movements and/or without the S-movement.

In some implementations, the arms <NUM>, <NUM> can be arranged so that a height of the Cephalometric patient support <NUM> with the ear rods <NUM> and nasion support <NUM> is fixed relative to the X-ray source <NUM>. However, the fixed height may cause problems, because an anatomy of patients <NUM> varies for example, the vertical distance where ear openings are located compared to patient's <NUM> shoulders differs significantly from one patient <NUM> to another. Thus, either the patient <NUM> is located too low in the resultant Cephalometric image, showing only upper vertebras, or the patient <NUM> is located so high in the images that the shoulder of the patient <NUM> touches the detector unit <NUM>, which is a problem especially with a scanning. Furthermore, the preferred Cephalometric imaging geometry requires that the focal spot and the tips of the ear rods <NUM> are at the same (horizontal) axis. In to reduce these problems, variable length ear rods <NUM> can be used while keeping the arms <NUM>, <NUM> fixed height relative to each other.

Alternatively or in addition, in order to eliminate these problems, the system <NUM> can include Cephalometric height adjusting means (not shown) that are configured to independently adjust the height--in respect to the column <NUM>--of the arms <NUM>, <NUM> that support the Cephalometric head <NUM> at the one end and the X-ray source <NUM> on the other end.

When the operator has adjusted the height of the arms <NUM>, <NUM> by means of an up/down Zc-movement, the focal spot follows the tips of the ear rods <NUM> automatically and, thus, the geometry (ear rod tip to focal spot line) remains intact. Yet, the detector unit <NUM> and the Cephalometric collimator <NUM> on each side of the patient <NUM> take their height from the column <NUM> and, thus, are on a different height in respect to the ear rods <NUM> and the patient <NUM> than before the adjustment.

The Cephalometric height adjusting means provides a way to adapt an exposed area to a given anatomy of the patient <NUM> by enabling an operator (user) to adjust the height of the patient <NUM> without compromising the geometry.

Since the first and second X-ray sources <NUM>, <NUM> can be arranged at different heights with respect to the column <NUM> in the Z direction by means of the height adapting means <NUM> and/or the Cephalometric height adjusting means, it is possible to position the patient <NUM> without any additional adjustment of the Cephalometric head <NUM> in the Z direction as it is needed when using the X-ray source <NUM> of the rotating part <NUM> for the Cephalometric imaging. The detector unit <NUM> and the secondary collimator <NUM> are positioned for imaging using L-movement, P-movement, and/or R-movement.

In addition, by using the P-movement, the structure of system <NUM> is made simpler and cheaper, because the Cephalometric imaging can optionally be implemented by using only one "non-detachable" detector unit <NUM>. This reduces the risk of breaking the detector unit <NUM> because there is no need to remove it from a holder of the rotating part <NUM> to detach it from a holder of the Cephalometric head <NUM> when changing the imaging mode from the Panoramic/CT mode to the Cephalometric mode. The detector for Panoramic imaging in the detector unit <NUM> can be rotated from the Panoramic imaging position to the Cephalometric imaging position so that it is possible to use the same detector in both Panoramic and Cephalometric imaging.

In addition, the structure of system <NUM> provides a simple workflow when, for example, the change from the Panoramic/CT mode to the Cephalometric mode--the movement of the rotating part <NUM> from the Panoramic/CT imaging position to the Cephalometric position without changing the detector unit <NUM> from one holder to other holder--is automated, thus decreasing both the amount of manual work required and the time needed for the work flow.

It is also possible that the system <NUM> includes the upper shelf <NUM> that pivots around the column <NUM> and the rotating part <NUM> that is configured to be positioned by means of the above-described L- , P-, and/or R-movements for providing the Panoramic and/or CT imaging, but has a more conventional Cephalometric head <NUM> comprising the Cephalometric detector, the secondary collimator, and the patient positioning support parts.

Cephalometric imaging is provided by means of the X-ray source <NUM> of the rotating part <NUM>, and the secondary collimator and the Cephalometric detector of the Cephalometric head <NUM>. The X-ray source <NUM> is arranged to scan the patient's <NUM> head with the R-, L-, and/or P-movements. The X-ray beam is collimated by the secondary collimator and captured by the Cephalometric detector, which are synchronized with the X-ray beam.

<FIG> illustrates a positioning of the x-ray imaging system <NUM> for Panoramic/CT imaging. A patient <NUM> will be positioned with their head supported by placing the chin of the patient <NUM> on the lower shelf <NUM> and possibly to the head support of the system <NUM> in a Panoramic/CT imaging position, where the rotating part <NUM> is over the lower shelf <NUM>.

If the upper shelf <NUM> as well as the rotating part <NUM> are in a different position than the Panoramic/CT imaging position--in a Cephalometric imaging position or in an intermediate position between, for example, the Panoramic/CT and Cephalometric imaging positions--the upper shelf <NUM> is moved from that position to the Panoramic/CT imaging position by the P-movement and, then, the rotating part <NUM> is further adjusted by the R- and L-movements so that the rotating part <NUM> is ready for the Panoramic/CT imaging. In implementations that include one or more other additional patient supports (e.g., a hand support for carpus imaging), the system <NUM> may be further configured to position the rotating part <NUM> proximate to each additional patient support for imaging using R-, L- and/or P-movements.

In addition, the rotating part <NUM> can have a patient positioning position, where the X-ray source <NUM> or the detector unit <NUM> are out of the way and do not interfere with the positioning of the patient <NUM> to the Panoramic/CT and/or Cephalometric imaging positions when the rotating part <NUM> is over the lower shelf <NUM> or the Cephalometric head <NUM>. The patient positioning position can be accomplished by the R-movement so that the rotating part <NUM> is rotated to such position, where it is possible to place the patient <NUM> to the Panoramic/CT and/or Cephalometric imaging positions or to remove the patient <NUM> by moving the patient's <NUM> head between the X-ray source <NUM> and the detector unit <NUM>. Alternatively, it is possible to realize the patient positioning position by means of the P-movement and/or the L-movement, whereupon the whole rotating part <NUM> is moved away from the Panoramic/CT and/or Cephalometric imaging positions, when the patient <NUM> is positioned.

The positioned X-ray source <NUM> and the detector unit <NUM> are configured to provide a Panoramic image when the rotation axis <NUM>--a rotation center of the rotating part <NUM>--is positioned by at least one of the P- and L-movements. In some implementations, the system is configured to perform Panoramic imaging by adjusting the P-, L-, and/or R-movements to control the position of the x-ray source <NUM> and the detector unit <NUM> before or during image capture scanning.

Depending on the sensor technology used, the image can be clocked out using a TDI mode or a full frame read-out mode of the detector. In the TDI mode, the image is read out one column at a time, whereas in the full frame mode, the image is read out whole image frame at a time. The Panoramic (sharp) layer is defined by the velocities of the movements and, in the case of TDI, the readout rate of the Panoramic detector. When using a full frame detector, the final shape of the layer is calculated on the computer after the scan. Rotation angle is, for example, about <NUM> degrees, but this is not intended to be limiting.

During CT imaging, the patient <NUM> is also supported by the lower shelf <NUM> and possibly by the head support of the system <NUM> in the Panoramic/CT imaging position. The X-ray source <NUM> and the detector unit <NUM> are configured to provide a CT image when the detector unit <NUM> is attached to the rotating unit and the rotation center of the rotating part <NUM> is positioned so that it can coincide with the ROI.

The positioned X-ray source <NUM> and the detector unit <NUM> are configured to provide a CT image, for example, CBCT image, when the detector unit <NUM> is attached to the rotating part <NUM>, and the rotation axis <NUM> is positioned by at least one of the R-, L-, and P-movements during the CT imaging.

When the system <NUM> is used with a symmetric imaging geometry, CT imaging can be carried out by using only the R-movement and reading out the CT detector in a full frame mode. Alternatively, or in addition, CT imaging can be carried out by using the P-, R-, and L-movements, using the controlling arrangement in the upper shelf <NUM>, for positioning the virtual rotation axis of the rotating part <NUM> so that it coincides with the ROI. Thus, projection X-ray images of the ROI are produced in a way that the center of the ROI and the R-movement coincide. In one embodiment, the effective rotation angle (aperture) ranges, for example, from approximately <NUM> to <NUM> degrees depending on the system <NUM>.

When the system <NUM> is used in an offset imaging, CT imaging can be carried out by scanning the image by using the R-, L-, and P-movement. By driving these R-, L-, and P-movements in synchronism, the effective center of the rotation can be deflected to the side of the X-ray beam and, thus creating an offset geometry. Offset scanning can be provided by a first "solid" offset geometry and a full <NUM> degree rotation of the CT detector.

Alternatively, the offset scanning can be provided by a second offset geometry, where the patient <NUM> is imaged by scanning an essentially maximal first imaging offset with approximately <NUM> degree rotation of the detector in a first imaging direction. Then, the detector is displaced to the other side of the rotation center to obtain an essentially maximal second imaging offset by approximately <NUM> degree rotation of the detector in a second imaging direction, which is opposite to the first direction. Alternatively, the detector is rotated to the starting position, displaced to the other side of the rotation center, and, then, scanning the essentially maximal second imaging offset by approximately <NUM> degree rotation in the first direction.

Alternatively, offset scanning can be provided by a third offset geometry, where the patient <NUM> is imaged by a first imaging offset, where the edge of the X-ray beam area touches the rotation center, and by <NUM> degree rotation of the detector. Next, the detector and the X-ray source <NUM> are displaced parallel in such a way that the X-ray beam area moves away from the rotation center so it hits or slightly overlaps the previously imaged area. Then, the detector is rotated <NUM> degrees for completing a second imaging offset.

The system <NUM> provides same versatility in the CT imaging geometry by means of the R-, L-, and P-movements instead of the R-, L-, X-, and N-movements required in imaging and patient positioning by some conventional systems.

<FIG> illustrates a positioning of the patient <NUM> and the x-ray system <NUM> during Cephalometric imaging. In the Cephalometric imaging position, where the rotating part <NUM> is over the patient support means <NUM>, <NUM> located at the Cephalometric head <NUM>, the patient <NUM> is supported to the patient support means <NUM>, <NUM>.

If the upper shelf <NUM> as well as the rotating part <NUM> are in a different position than the Cephalometric imaging position, for example, in a Panoramic/CT imaging position or in an intermediate position between the Panoramic/CT and Cephalometric imaging positions--the upper shelf <NUM> is moved from that position to the Cephalometric imaging position by the P-movement, and then the rotating part <NUM> is further adjusted by the R- and L-movements so that the rotating part <NUM> is ready for the Cephalometric imaging.

The positioned X-ray source <NUM> is configured to scan the supported patient <NUM> by means of the X-ray beam limiting device <NUM> attached to the X-ray source <NUM> and by means of the S-movement. The detector unit <NUM>--and the rotating part <NUM>--is configured to move synchronously with the X-ray source <NUM> by at least two of the R-, L-, and P-movements during the Cephalometric imaging.

The X-ray beam from the X-ray source <NUM> is arranged to scan the patient's <NUM> head by rotating the X-ray source <NUM> and the X-ray beam limiting device <NUM> with the S-movement around the axis <NUM>. Alternatively, the S-movement can be performed by moving (for example, linearly) the X-ray beam limiting device <NUM>. It is also possible that the S-movement is provided as a vertical scanning movement instead of the horizontal S-movement, if the detector of the detector unit <NUM> used in Cephalometric imaging is positioned horizontally. Alternatively, Cephalometric imaging can be performed without the S-movement if a sufficiently large detector (so-called, "one shot" detector) is used for the one-shot Cephalometric image.

The X-ray beam is then further collimated by the Cephalometric collimator <NUM> and finally captured by the synchronously moved Cephalometric or combination detector in the detector unit <NUM>. The system <NUM> simplifies the movements during the Cephalometric imaging, because no additional movement means are needed for the Cephalometric collimator <NUM> and the detector of the detector unit <NUM>.

As noted above, during Cephalometric imaging, the rotating part <NUM> is moved into position around the Cephalometric patient support <NUM> (e.g., with the X-ray source <NUM> and the detector unit <NUM> positioned on opposite sides of the Cephalometric patient support <NUM>). <FIG> is a side view of a patient <NUM> positioned for Cephalometric imaging using the Cephalometric patient support <NUM>. The patient <NUM> is positioned with the ear buds of the adjustable ear rod <NUM> positioned in each ear and with the adjustable nasion support <NUM> contacting the bridge of the nose of the patient <NUM>. Although the nasion support <NUM> is shown in <FIG> as contacting the bridge of the nose, in some implementations, the adjustable nasion support <NUM> may be sized and positioned for the nose of the patient <NUM> to rest on top of the adjustable nasion support <NUM> during Cephalometric imaging.

<FIG> illustrates the functional elements (e.g., the control system) of the system <NUM>. The system <NUM> includes a controller <NUM> that receives input from a control panel and that is configured to control the system <NUM>, and its above-described movements and imaging processes. The controller <NUM> is attached, for example, to the column <NUM>. The controller <NUM> includes at least one processor <NUM> for performing user and/or software initiated instructions and for processing data, and at least one non-transitory computer-readable memory <NUM> for storing and maintaining data, for example, instructions, software, and data files. Although <FIG> shows only a single controller <NUM>, in some implementations, the system <NUM> is configured to include multiple different controllers to provide the functionality of the system <NUM>.

In addition, the controller <NUM> includes a data transfer portion <NUM> for sending control commands to one or more movement actuators <NUM>, for example, the pivot, linear, height, rotating, detector, X-ray beam limiting, and collimator motors, drivers, or other means configured to provide the movements of the parts of the system <NUM>, and/or receiving data from measuring devices or other detection devices <NUM> configured to detect the function of parts of the system <NUM>.

In addition, the data transfer portion <NUM> is also configured to send control commands to the at least one of followings: at least one of X-ray source <NUM> and/or X-ray source <NUM>, and the detector unit <NUM>. The data transfer portion <NUM> is also configured to receive information from at least one of the following: the at least one X-ray source <NUM>, <NUM>, and the detector unit <NUM>.

In addition, the controller <NUM> includes a user interface portion <NUM> which may include at least one of the following: at least one function key, a touchscreen, and a wired or wireless remote controller, for inputting control commands, and for receiving information and/or instructions.

The at least one memory <NUM> stores at least a data transfer application <NUM> for execution by the processor <NUM> controlling the data transfer portion <NUM>, a user interface application <NUM> for execution by the processor <NUM> for controlling the user interface portion, and a computer program (code) <NUM> for controlling the function of the system <NUM>, for example, at least the movement devices <NUM>, detection devices <NUM>, the at least one X-ray source <NUM>, <NUM>, and the detector unit <NUM>. In addition, execution of the computer program <NUM> can control, for example, imaging parameters, imaging sizes, and imaging modes.

The at least one memory <NUM> and the computer program <NUM> are configured to, with the at least one processor <NUM>, cause the system <NUM> at least to provide actions described in context of <FIG>, for example, to control positions of the detector unit <NUM> and the Cephalometric collimator <NUM> by at least one or two of the R-, L-, and P-movements.

The computer program <NUM> can be a computer program product that includes a tangible, non-volatile (non-statutory) computer-readable medium bearing a computer program <NUM> embodied therein for use with a computer (controller <NUM>).

<FIG> illustrates one example of a detector unit <NUM> that includes two detectors 227a, 227b, which can provide a Panoramic, CT, and Cephalometric image. The rotating part <NUM> includes moving means <NUM>, which move the at least one detector 227a, 227b relative to the rotating part <NUM> for positioning the at least one detector 227a, 227b for the imaging, and the detector motor <NUM> configured to drive the moving means <NUM>. The detector 227a can be, for example, a Panoramic detector, which is configured to provide the Panoramic image, or a Cephalometric detector, which is configured to provide a Cephalometric image and a Panoramic image. The CT detector 227b is configured to provide a CT image. The moving means <NUM> can comprise, for example, at least one of rails 231a, 231b, a threaded rod <NUM>, a conveyor unit <NUM>, a guide unit <NUM> that is connected to the conveyor unit <NUM> and attaches the detector 227a to the rotating part <NUM>, and a guide groove <NUM>. The detector motor <NUM> moves the detector 227a by means of the threaded rod <NUM>, which moves the conveyor unit <NUM> along the rails 231a, 231b so that the guide unit <NUM> guides the detector 227a along the guide groove <NUM>. The guide groove <NUM> illustrated in the example of <FIG> is only one example and, in other implementations, the guide groove <NUM> can be provided in other shapes and configurations including a groove that is, for example, direct, curved, devious, or combinations thereof.

<FIG> illustrates one example of a Panoramic imaging position, wherein the X-ray source <NUM> and the Panoramic or Cephalometric detector 227a, which is attached to the rotating part <NUM>, can provide the Panoramic image. The detector 227a and the CT detector 227b are arranged successively in the Panoramic imaging position so that the detector 227a is between the X-ray source <NUM>, <NUM> and the CT detector 227b--the detector 227a is in front of the CT detector 227b relative to the X-ray source <NUM>, <NUM>. To capture CT image data, the detector motor <NUM> operates the moving means <NUM> to move the detector 227a along the guide groove <NUM> until the guide unit <NUM> is positioned at the opposite end of the guide groove <NUM> and the detector 227a is no longer positioned between the CT detector 227b and the x-ray source <NUM>. In some embodiments, the CT imaging position can also be a Cephalometric imaging position, wherein the X-ray source <NUM> can provide together with the Cephalometric detector 227a, which is attached to the rotating part <NUM>, the Cephalometric image.

As discussed above, in some embodiments, the first X-ray source <NUM> and the combination detector <NUM>, which is attached to the rotating part <NUM>, are used for providing the Panoramic image and the CT <NUM> image. The second X-ray source <NUM> and the combination detector <NUM>, which is attached to the rotating part <NUM>, are used for providing the Cephalometric image. The combination detector <NUM> can be driven similarly as the detector 227a in the detector unit <NUM> illustrated in <FIG> by for example, similar moving means <NUM>, but not necessary by all its movements.

The Panoramic image is taken when the combination detector <NUM> has been driven to the Panoramic imaging position similarly as illustrated in <FIG>, whereupon the combination detector <NUM> is in a front position. The CT and Cephalometric images are taken when the combination detector <NUM> has been driven to the CT/Cephalometric imaging position whereupon the combination detector <NUM> is in a back position. In addition, the combination detector <NUM> can be positioned by means of the moving means <NUM> and by means of at least one of the R-, L-, and P-movements. Alternatively, the combination detector <NUM> can be positioned by means of at least one of the R-, L-, and P-movements. So, the combination detector <NUM> can be moved between at least of two of the Panoramic, CT, and Cephalometric imaging positions by means of the moving means <NUM> and/or by means of at least one of the R-, L-, and P-movements.

In order for the system <NUM> to be able to properly perform Cephalometric imaging in the position/configuration shown in <FIG>, the system <NUM> must be able to determine, for example, a position of the patient's head relative to the detector unit <NUM> and/or the Cephalometric x-ray source <NUM>. In some implementations, the position of the patient's head can be inferred based on a position of the Cephalometric patient support <NUM>. However, the position of the Cephalometric patient support <NUM> may not be precisely known by the imaging system <NUM>. As discussed above, the first arm <NUM> and the second arm <NUM> of the Cephalometric imaging system are installed after the components for Panoramic and CT imaging are installed and calibrated. For example, the first arm <NUM> and the second arm <NUM> may be added to the system <NUM> as "add-ons" or accessories and, therefore, are not calibrated at the time of manufacture of the system <NUM>. Additionally, in some implementations, the position of the first arm <NUM>, the ear rod <NUM>, and/or the nasion support <NUM> can be manually adjusted based for a particular patient <NUM>.

In these and other situations, the system <NUM> must be calibrated, for example, to determine a position of the Cephalometric patient support <NUM> in a three-dimensional coordinate space used by the system <NUM>. Additionally, in some implementations, the appropriate relative angles and positions of the Cephalometric x-ray source <NUM> and the secondary collimator <NUM> are determined relative to the position of the patient's head. The position of the Cephalometric patient support <NUM> and/or the appropriate relative angles and positions of the Cephalometric x-ray source <NUM> and the secondary collimator <NUM> can be determined, for example, by performing one or more calibration "sweeps. " A calibration sweep is performed by controllably adjusting a position of one or more component of the system <NUM> while emitting x-rays (e.g., from the first x-ray source <NUM> or the Cephalometric x-ray source <NUM>) and while capturing image data through the detector unit <NUM>.

In some implementations, a calibration phantom is used in the calibration process. The calibration phantom can be permanently or selectively affixed to the Cephalometric patient support <NUM>. <FIG> illustrates a first example of a calibration phantom <NUM> that is selectively affixed to the Cephalometric patient support <NUM> at a position equidistant between the ear rods <NUM>. As discussed below, this calibration phantom <NUM> can be detected in the image data captured during the calibration process and used to determine a position of the Cephalometric patient support at least in the horizontal (x, y) plane.

<FIG> illustrates another example of a calibration phantom <NUM> that is selectively affixed to the Cephalometric patient support. The calibration phantom <NUM> of <FIG> includes a spherical body <NUM> coupled to a distal end of the linear rod. Because the actual size and dimensions of the spherical body <NUM> are known, the calibration phantom <NUM> can be used, for example, to determine a distance between the x-ray detector and the calibration phantom <NUM> (and, by extension, the Cephalometric patient support <NUM>).

<FIG> illustrates yet another example of a calibration phantom <NUM> that is provided in the form of an inverted "T" and coupled to the Cephalometric patient support <NUM>. The calibration phantom <NUM> includes two spherical bodies <NUM>, <NUM> attached to the ends of the horizontal portion of the calibration phantom <NUM>. In this example, the spherical bodies <NUM>, <NUM> are provided with different diameters and the diameters of spherical bodies <NUM>, <NUM> are known. Accordingly, as discussed in further detail below, a distance between the x-ray detector unit <NUM> and each spherical body <NUM>, <NUM> of the calibration phantom <NUM> can be determined based on an apparent magnification of the spherical bodies in captured image data.

<FIG> illustrates still another example of a calibration phantom <NUM>. The calibration phantom <NUM> includes a linear body with a coupling notch <NUM> formed at a first end that selectively engages with a corresponding coupling on the Cephalometric patient support <NUM> in order to selectively couple and de-couple the calibration phantom <NUM> to a position on the Cephalometric patient support <NUM> (e.g., extending vertically downward from the Cephalometric patient support <NUM> as shown in <FIG> with respect to calibration phantom <NUM>). The calibration phantom <NUM> also includes a plurality of grooves <NUM>, <NUM>, <NUM> formed around the circumference of the linear body of the calibration phantom <NUM> at different locations along the length of the calibration phantom <NUM>. In some implementations, the grooves can be formed on the calibration phantom <NUM> with different widths - for example, the first groove <NUM> in the example of <FIG> is wider than the second groove <NUM>. Similarly, the grooves can be positioned along the length of the calibration phantom <NUM> to provide, for example, different lengths of the linear body of the calibration phantom <NUM> between different grooves pairs. For example, in the calibration phantom <NUM> illustrated in the example of <FIG>, a section <NUM> of the linear body between the first groove <NUM> and the second groove <NUM> is shorter than a section <NUM> of the linear body between the second groove <NUM> and the third groove <NUM>. Although the example illustrated in <FIG> includes three grooves, in other implementations, the calibration phantom <NUM> can be formed with more or fewer grooves. For example, in some implementations, the calibration phantom may be formed to include only one groove.

<FIG> illustrates an example of a method for calibrating the system <NUM>. The calibration method of <FIG> utilizes the calibration phantom <NUM> of <FIG> - a stick mounted to the ear rods rotation axis at the Cephalometric patient support <NUM> (e.g., extending vertically downward midway between the ear buds). In the example of <FIG>, the system <NUM> is configured to display on the user interface, upon initiation of the calibration process, an instruction to place the calibration phantom on the middle axis of the Cephalometric patient support <NUM> (step <NUM>). Because the position of the x-ray source <NUM> and the detector unit <NUM> are controlled based on a known coordinate system, the system <NUM> can determine the position of the Cephalometric patient support <NUM> in the same known coordinate system by performing one or more imaging scans. In the example of <FIG>, the system <NUM> determines the middle point of the Cephalometric patient support <NUM> by performing two different scans. First, the system performs a "pivot sweep calibration" (step <NUM>) by adjusting the pivot of the upper shelf <NUM> (e.g., P-rotation) in order to a scan the space containing the Cephalometric patient support <NUM> in a first direction. The system then performs a "linear sweep calibration" (step <NUM>) in order to scan the space in a second direction. As described in further detail below, based on these two calibration scans, the system <NUM> is able to determine a middle point of the Cephalometric patient support <NUM> in the x-y plane in the known coordinate system of the imaging system <NUM>.

After determining the middle position of the Cephalometric patient support <NUM>, the user is instructed to remove the calibration phantom (step <NUM>) and the system performs a "Cephalometric tube sweep calibration" (step <NUM>) in order to determine a "middle angle" position of the Cephalometric x-ray source <NUM> relative to the Cephalometric patient support <NUM>. The system also performs a "secondary collimator sweep calibration" (step <NUM>) to determine an appropriate position/orientation of the secondary collimator <NUM> relative to the Cephalometric x-ray source <NUM>. In some implementations, the system may also apply one or more mechanical calibration steps (step <NUM>) and/or a pixel calibration (step <NUM>) before using the calibrated system to perform Cephalometric imaging.

<FIG> illustrates one example of a pivot sweep calibration <NUM> in further detail. After the calibration phantom is positioned on the Cephalometric patient support <NUM>, the system <NUM> operates the pivot actuator to pivot the upper shelf <NUM> to a nominal Cephalometric imaging position (step <NUM>). Because the pivoting movement of the upper shelf <NUM> and the rotating part <NUM> have already been calibrated (e.g., during manufacture), the system <NUM> is aware of the position of the first x-ray source <NUM> and the detector unit <NUM> in the known coordinate system. The rotating part <NUM> is rotated to a position where the upper shelf <NUM> can be pivoted without interfering with or contacting the Cephalometric patient support <NUM> (e.g., positioned with the detector unit <NUM> and first x-ray source <NUM> in line with the upper shelf <NUM>). The first x-ray source <NUM> is then activated to irradiate the calibration phantom <NUM> (step <NUM>) and the system operates the pivot rotation (p-rotation) to scan the space occupied by the Cephalometric patient support <NUM> (step <NUM>). As the pivoting of the upper shelf <NUM> causes movement of the first x-ray source <NUM> and the detector unit <NUM>, image data is captured by the detector unit <NUM> (step <NUM>). After the pivot scan is complete, the image data is analyzed to determine a center of the calibration phantom <NUM> (step <NUM>).

<FIG> illustrates one example of a linear sweep calibration <NUM> in further detail. After completing the pivot sweep calibration <NUM>, the rotating part <NUM> is rotated approximately <NUM>-degrees (step <NUM>) so that a line between the first x-ray source <NUM> and the detector unit <NUM> is perpendicular to a length of the upper shelf (e.g., a line extending radially from the pivot axis). In this way, the rotating part <NUM> is able to move linearly along the length of the upper shelf <NUM> without contacting the Cephalometric patient support <NUM>. The system <NUM> activates the first x-ray source <NUM> to irradiate the calibration phantom <NUM> (step <NUM>) and operates a linear movement actuator to move the rotating part <NUM> in a linear direction along the length of the upper shelf <NUM> (step <NUM>). As the linear movement of the rotating part <NUM> causes movement of the first x-ray source <NUM> and the detector unit <NUM>, image data is captured by the detector unit <NUM> (step <NUM>). After the linear sweep scan is complete, the image data is analyzed to determine a center of the calibration phantom <NUM> (step <NUM>).

By determining the middle point of the calibration phantom <NUM> while performing both the linear sweep and the pivot sweep, the system <NUM> is now able to determine a location of a center point of the Cephalometric patient support in the x-y plane of the known coordinate system. In some implementations, the system <NUM> is configured to utilize a separate alignment procedure to properly align the Cephalometric patient support <NUM> in the vertical (Z) direction.

As described above in reference to <FIG>, after the system <NUM> has determined the position of the Cephalometric patient support <NUM> in the known coordinate system of the imaging system <NUM>, the calibration phantom <NUM> can be removed. The system <NUM> then determines appropriate positioning of other system components relative to the Cephalometric patient support <NUM>.

As discussed above, in performing Cephalometric imaging, the system <NUM> will rotate the Cephalometric x-ray source <NUM> (S-rotation in <FIG>) while making corresponding adjustments to the position of the detector unit <NUM>. However, in order to perform this type of scan, a position and orientation of the Cephalometric x-ray source <NUM> relative to the Cephalometric patient support <NUM> must be determined. <FIG> illustrates an example of a Cephalometric tube sweep calibration <NUM> that can be used by the system <NUM> to determine a middle angle of the Cephalometric x-ray source <NUM> relative to the Cephalometric patient support <NUM>. The detector unit <NUM> is moved into position by adjusting the pivot of the upper shelf <NUM> (P-rotation), a linear position of the rotating part <NUM> along the length of the upper shelf, and a rotation of the rotating part <NUM> (R-rotation) (step <NUM>). Additionally, in some implementations, the rotational position of the rotating part <NUM> and the position of the detector unit <NUM> are adjusted so that the x-ray beam from the Cephalometric x-ray source <NUM> does not pass through the secondary collimator before contacting the detector unit <NUM> (step <NUM>). For example, as illustrated in <FIG>, the linear position of the detector 227a that is used for capturing image data during panoramic and Cephalometric imaging can be moved to an appropriate position along the guide groove <NUM> for calibration while the P-, L-, and/or R-movements are adjusted to position the detector 227a relative to the previously determined center point of the Cephalometric patient support <NUM>.

After the detector unit <NUM> is positioned based on the previously determined center points of the Cephalometric patient support <NUM> and the secondary collimator <NUM> is moved out of the way, the Cephalometric x-ray source <NUM> is activated (step <NUM>) and the Cephalometric x-ray source <NUM> is controllably rotated for scanning (step <NUM>). Image data is captured by the detector unit <NUM> while the rotating unit <NUM> (and, therefore, the detector unit <NUM> and the secondary collimator <NUM>) remains stationary (step <NUM>). The captured data is then analyzed, for example, to determine the angular position of the Cephalometric x-ray source <NUM> that results in the maximum image intensity (step <NUM>). In some examples, this angular position is then used to define a "middle angle" of the Cephalometric x-ray source <NUM> to guide movement of the Cephalometric x-ray source <NUM> (e.g., S-rotation) during Cephalometric imaging (step <NUM>). In other implementations, for example, angular positions of the Cephalometric x-ray source <NUM> corresponding to the edges of the captured image data are determined and the "middle angle" of the Cephalometric x-ray source is determined based on a middle point between the detected edges of the image data.

Although the examples described above in reference to <FIG>, <FIG> refer to the use of the calibration phantom <NUM> as illustrated in <FIG>, the pivot sweep calibration of <FIG> and the linear sweep calibration of <FIG> can be performed using other types of calibration phantoms - for example, the calibration phantom <NUM> of <FIG>.

After the position/location of the Cephalometric patient support <NUM> is determined relative to the x-ray detector and the position of the Cephalometric x-ray source <NUM> is calibrated relative to the Cephalometric patient support <NUM>, the system <NUM>, in the example of <FIG>, then performs a "secondary collimator sweep calibration" <NUM> to calibrate the positioning of the secondary collimator between the Cephalometric x-ray source <NUM> and the detector unit <NUM>. <FIG> illustrates one example of a secondary collimator sweep calibration <NUM> that can be used to calibrate the position and orientation of the secondary collimator <NUM> for Cephalometric imaging. First, the Cephalometric x-ray source <NUM> is returned to the middle angle as determined in the "ceph tube sweep calibration" <NUM> (step <NUM>). The rotating part <NUM> is then controllably rotated to position the detector unit <NUM> relative to the Cephalometric patient support <NUM> and to position the secondary collimator <NUM> between the Cephalometric x-ray source <NUM> and the detector unit <NUM> (step <NUM>). The Cephalometric x-ray source <NUM> is then activated (step <NUM>) and the position of the secondary collimator <NUM> is controllably adjusted for scanning (step <NUM>). While the position and angle of the secondary collimator <NUM> are controllably adjusted, the detector unit <NUM> captures image data (step <NUM>) and the Cephalometric x-ray source <NUM> remains stationary. The captured image data is then analyzed, for example, to detect collimation edges (step <NUM>) and to detect a collimator position that results in a maximum intensity between the detected collimation edges (step <NUM>). In some examples, a "middle pose" of the secondary collimator <NUM> is then defined based on the position that is determined to result in the maximum intensity (step <NUM>).

After the system is calibrated to determine a position/location of the Cephalometric patient support <NUM> relative to the x-ray detector and to determine "middle positions" for both the Cephalometric x-ray source <NUM> and the secondary collimator <NUM>, Cephalometric imaging can be performed by capturing image data while controllably coordinating the movements of the Cephalometric x-ray source <NUM>, the secondary collimator <NUM>, and the detector unit <NUM> (see, e.g., step <NUM> in <FIG>). However, in some implementations, additional calibration procedures may be performed before operating the system <NUM> for Cephalometric imaging. For example, in <FIG> a mechanical calibration <NUM> and a pixel calibration <NUM> are performed.

In some implementations, the mechanical calibration <NUM> may be performed to align the ear rods <NUM> of the Cephalometric patient support <NUM> so that they overlap at the image plane at the ear rod rotation axis. This can be achieved, for example, by exposing a lateral Cephalometric image and displaying instructions on the user interface <NUM> instructing the user to make particular mechanical adjustments to the Cephalometric patient support <NUM>.

Furthermore, in some implementations, the pixel calibration <NUM> can be used to calibrate pixel response and/or to find dead pixels in the detector unit <NUM> in order to create a "blemish map. " This can be achieved, for example, by positioning the rotating part <NUM>, the secondary collimator <NUM>, and the Cephalometric x-ray source <NUM> in the "middle position" (e.g., where image intensity is the strongest). Image data is then captured by the detector unit <NUM> while all system components remain stationary. The captured image data is then analyzed to detect any dead pixels and to calibrate for pixel response.

In the method of <FIG>, the center position of the Cephalometric patient support <NUM> is determined by performing both a pivot sweep scan and a linear sweep scan while a calibration phantom is irradiated using the first x-ray source <NUM> coupled to the rotating part <NUM>. However, in other implementations, the system <NUM> may be configured to determine the center position of the Cephalometric patient support <NUM> using one or more other "sweeps. " Also, in other implementations, the system <NUM> may be configured to irradiate the calibration phantom using the Cephalometric x-ray source <NUM>.

<FIG> illustrates an example of an alternative calibration method for determining a position of the Cephalometric patient support <NUM>. In this example, a calibration phantom that includes a body of known size and dimensions - for example, the known dimensions of the spherical bodies <NUM>, <NUM> of the calibration phantom <NUM> in <FIG>, the known width of the grooves <NUM>, <NUM>, <NUM> of the calibration phantom <NUM> in <FIG>, and/or the known length and width of the sections <NUM>, <NUM> between the grooves <NUM>, <NUM>, <NUM> of the calibration phantom <NUM> in <FIG> - is affixed to the Cephalometric patient support <NUM>. Once the calibration phantom (for example, the calibration phantom <NUM> or the calibration phantom <NUM>) is attached, the system <NUM> begins the calibration routine by activating the Cephalometric x-ray source <NUM> to irradiate the calibration phantom <NUM>/<NUM> (step <NUM>). Image data is captured by the detector unit <NUM> (e.g., the combined detector illustrated in <FIG>) (step <NUM>). The captured image data is analyzed and, based on a known size and known dimensions of the calibration phantom <NUM>/<NUM> and the apparent size/dimensions of the calibration phantom <NUM>/<NUM> in the captured image data, a magnification of the calibration phantom <NUM>/<NUM> is determined (step <NUM>). The system <NUM> then adjusts a position of the detector relative to the calibration phantom <NUM>/<NUM> using a combination of L-, R-, and P-movements (step <NUM>) until the scan is complete (step <NUM>). The position of the calibration phantom <NUM>/<NUM> in the coordinate space for the system <NUM> is then calculated based on the determined magnification of the calibration phantom <NUM>/<NUM> in image data captured at each of a plurality of known positions of the detector unit <NUM> (step <NUM>).

When using a calibration phantom with multiple bodies of known size/dimension, the system <NUM> may be configured to separately determine a magnification of the each body in image data. For example, in the image data captured at each of the plurality of known detector positions while using the calibration phantom <NUM> of <FIG>, the system <NUM> may be configured to detect both spherical bodies <NUM>, <NUM> in the image data and to then calculate a relative magnification of each of the two spherical bodies <NUM>, <NUM>. Similarly, in the image data captured at each of the plurality of known detector positions while using the calibration phantom <NUM> of <FIG>, the system <NUM> may be configured to calculate a relative magnification of each of the grooves <NUM>, <NUM>, <NUM> and/or each sections <NUM>, <NUM> between the grooves. Based on the magnification ratio of the two spherical bodies <NUM>, <NUM>, the grooves <NUM>, <NUM>, <NUM>, and/or the sections <NUM>, <NUM> at each of a plurality of different detector positions, the system <NUM> determines a distance between the detector unit <NUM> and the calibration phantom <NUM>/<NUM> at each of the detector positions. Based on this collection of determined distances and the known position/orientation of the detector unit <NUM> corresponding to each determined distance, the system <NUM> then determines a location of the calibration phantom <NUM>/<NUM> in the coordinate space of the system <NUM>. Additionally, in some examples, the system <NUM> might also be configured to determine a position of the Cephalometric x-ray source <NUM> based on the magnification of the calibration phantom <NUM>/<NUM> in the image data (e.g., using the principle of source-object-distance (SOD)).

Although, <FIG> describes the adjustment of the L-, R-, and/or P-position of the system <NUM> as a discrete iterative step (step <NUM>) performed after capturing data, in some implementations, movement of the detector unit <NUM> by L-, R-, and/or P-movements is performed as a continuous sweep and image data is captured by the detector unit <NUM> at different times/positions during continuous movement. Accordingly, the calibration method illustrated in <FIG> can be performed as a single "sweep" calibration. Furthermore, the path of the detector unit <NUM> during the sweep calibration of <FIG> can be defined and/or adjusted in various different examples based, for example, on the size, position, and dimensions of the imaging system <NUM>, the patient support for which the system <NUM> is being calibrated, and/or the calibration phantom used in the calibration.

Finally, in some implementations, the system may be configured to utilize the additional calibration steps (including, for example, those illustrated in <FIG> and <FIG>) to determine a middle angle of the Cephalometric x-ray source <NUM> and/or the secondary collimator <NUM> after determining the position of the Cephalometric patient support <NUM> using the method of <FIG> (or another calibration method).

The examples described above are only some of the possible calibration techniques that can be used for a combination CT, panoramic, and/or Cephalometric imaging system. In various implementations, some or all of the calibrations illustrated in <FIG> may be performed. Other implementations may include additional or alternative calibrations.

Some embodiments described herein may include one or more electronic processors configured to perform the described functionality by executing instructions stored in non-transitory, computer-readable medium. Similarly, embodiments described herein may be implemented as non-transitory, computer-readable medium storing instructions executable by one or more electronic processors to perform the described functionality. As used in the present application, "non-transitory computer-readable medium" comprises all computer-readable media but does not consist of a transitory, propagating signal. Accordingly, non-transitory computer-readable medium may include, for example, a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a ROM (Read Only Memory), a RAM (Random Access Memory), register memory, a processor cache, or any combination thereof.

Claim 1:
A method of operating an imaging system (<NUM>) to perform Cephalometric imaging, the imaging system comprising
a column (<NUM>),
an upper shelf (<NUM>) pivotally coupled to the column,
a rotating part (<NUM>) coupled to the upper shelf and linearly translatable along a length of the upper shelf in a direction radial to the column,
a first x-ray source (<NUM>) coupled to the rotating part,
an x-ray detector (<NUM>) coupled to the rotating part on an opposite side of a first imaging volume from the first x-ray source, and
a Cephalometric patient support (<NUM>),
characterized in that the method comprising at least following steps of performing (<NUM>, <NUM>) at least one calibration sweep by controllably adjusting (<NUM>) a pivot angle of the upper shelf and by controllably adjusting (<NUM>) a linear position of the rotating part along the upper shelf to move a position of the x-ray detector relative to the Cephalometric patient support while emitting x-rays from the first x-ray source; capturing (<NUM>, <NUM>) image data by the x-ray detector while performing the at least one calibration sweep; and determining (<NUM>, <NUM>) a center position of the Cephalometric patient support relative to the imaging system in at least two dimensions based on the image data captured while performing the at least one calibration sweep.