Patent Description:
In a lithotripsy system, X-ray images are taken from a patient. These images are used for locating a stone and for aligning a therapy source like a shock wave or ultrasound therapy source. Such an X-ray image shows a projection into a plane orthogonal to the X-ray beam, herein referred ax X-Y plane. An information about the height, herein the Z-axis is not available. When the X-ray source is rotated about a predetermined angle alpha about a rotation axis parallel to the X-Y plane, all points at the rotation axis remain at their position.

In view of this, the lithotripsy system is calibrated such that the focal area of the therapy source is at the rotation axis. This is done by taking at least two X-ray images under different angles alpha1 and alpha2 and comparing the positions of an object, e.g., stone or calibration object in the X-ray images. If the position differs, the object is not at the rotation axis. Normally, the X-ray system is moved to bring the object into the rotation axis.

<CIT> discloses a lithotripsy system where the X-ray system can be mechanically coupled to the shockwave source for alignment. The axis of the x-ray system should be parallel to the axis of the shockwave source, further the focal area of the shockwave source should be on the axis of the x-ray system. This allows for proper triangulation and targeting. Mechanically coupling is a straightforward approach which requires a complex mechanical system and prevents separating the X-ray device from the shockwave device.

<CIT> discloses a shock wave therapy device with dynamic target tracking. <CIT> discloses a breast biopsy device. <CIT> discloses a shockwave therapy system with 3D control. <CIT> discloses an electromagnetic navigation system.

The problem to be solved by the invention is to provide an ultrasound and/or shock wave device, including an ultrasound and/or shockwave source and an X-ray system wherein the ultrasound and/or shockwave source is automatically aligned with the X-ray system without mechanically coupling between the ultra-sound and/or shockwave source without mechanically coupling. The ultrasound and/or shock wave device should be comparatively robust and simple to use. Solutions of the problem according to the invention are defined in the independent claims. The dependent claims relate to further improvements of the invention.

In an embodiment, a shock wave and/or ultrasound device, which may be a lithotripter includes an ultrasound and/or shockwave source together with an X-ray system including an X-ray source and a detector. It may further include a patient table. The ultrasound and/or shockwave source is suspended on a hexapod, such that it can be displaced in three degrees of freedom and tilted or rotated about two or three degrees of freedom. Therefore, no complex X-ray system mechanism and complex X-ray adjustment procedures are required. The X-ray system may only be aligned coarsely. The treatment source may then be adjusted by the hexapod drive such that the axes of the X-ray system and the treatment source are the same. As the hexapod allows a free orientation of the source in space, it can basically adjust the treatment source to any orientation of the X-ray source.

The X-Ray system, the ultrasound and/or shockwave source are oriented in a cartesian coordinate system as follows: a y-axis may be a longitudinal axis through the center of the table. An x-axis may be orthogonal to the y-axis and in the plane of the table surface. A z-axis is orthogonal to the plane of the table surface and therefore orthogonal to the x-axis and the y-axis and in a direction upward from the table. There may also be a first rotation around the x-axis, a second rotation and a third rotation around the z-axis. A positive rotation may be a clockwise rotation in a direction of a positive axis.

The orientation of the ultrasound and/or shockwave source is defined by an axis extending from the center of the source to the center of the focal area. The orientation of the X-ray system is defined by an axis at the path of the X-ray beam between the X-ray source and the detector.

The shock wave or ultrasound therapy system may include a system controller which may control at least the X-ray system and the hexapod drive of the ultra-sound and/or shockwave source. The system controller may control the X-ray system for taking at least one X-ray image which may show a known object, which may be a calibration object or at least a part of the ultrasound and/or shockwave source. The known object, may be a calibration phantom or focal phantom and may include a first X-ray absorbing object and a second X-ray absorbing object arranged distant from each other symmetrically to or at the axis of the ultrasound and/or shockwave source. Both X-ray absorbing objects may have different sizes and a symmetrical structure. They may be rings of different diameters. The known object may also be part of the structure of the shock wave and/or ultrasound therapy system, which is visible in an X-ray image.

The system controller may be configured to control the X-ray system to take a first image showing a first X-ray absorbing object and a second X-ray absorbing object.

The system controller may be configured to process the first image, to detect the first and second X-ray absorbing objects and to estimate the displacement of axes between a center axis of the ultra-sound and/or shockwave source and a center axis of the X-ray system. This may be done based on calculating the centers of and/or the distance between the X-ray absorbing objects.

The system controller may further be configured to control the hexapod drive for moving of the ultrasound and/or shockwave source to compensate for the displacement of axes.

The system controller may further be configured to control the X-ray system to take a second image showing a first X-ray absorbing object and a second X-ray absorbing object.

The system controller may be configured to process the second image, to detect the first and second X-ray absorbing objects and to estimate the displacement of axes between a center axis of the ultra-sound and/or shockwave source and a center axis of the X-ray system. The system controller may further be configured to control the hexapod drive for further adjustment if the displacement of axes is above a limit value. This may be repeated until the displacement of axes is below or equal to the limit value or a maximum count of iterations have been reached.

The system controller may be configured to take at least a further image after changing alignment of the ultrasound and/or shockwave source to verify the alignment. It may further be configured to repeat the steps above until an alignment within predetermined limits is reached or an operator is satisfied, or a maximum number of cycles is reached.

The ultrasound and/or shockwave source may be of any type suitable for generating shock waves. It may include a shock wave generator and/or transducer, which may include at least one of a coil, a spark gap or a Piezo transducer. The shock wave generator/transducer may be partially enclosed by a reflector. Depending on the type of transducer, the reflector may have a parabolic or half-elliptic shape. In case of a piezo transducer, the transducer may itself have a spherical shape, such that a reflector may not be needed. The ultrasound and/or shockwave source may have a focal volume which is distant from the ultrasound and/or shockwave source and normally around a center axis of the ultrasound and/or shockwave source. The focal volume may be defined as a volume, where the maximum shock wave intensity is maintained with a deviation of maximal -<NUM> dB or -<NUM> dB. If the focal volume is defined with a <NUM> dB deviation, the pressure at the limit of the zone is half of the maximum pressure inside the zone. The focal volume may have an elliptical shape with a length in an axial direction (defined by the center axis) of the ultrasound and/or shockwave source axis of <NUM> to <NUM> and a diameter between <NUM> and <NUM>. The focal volume normally is spaced from the shock wave generator and/or transducer.

The hexapod drive bearing the ultrasound and/or shockwave source is also known as a hexapod platform. Such a hexapod platform also is called a Stewart platform. Basically, it is a type of parallel manipulator or parallel robot that has six linear actuators, which may be hydraulic or pneumatic jacks or electric linear actuators. Examples of electric linear actors are motors coupled to a belt or a spindle to perform a linear movement. These linear actuators are connected in pairs to three mounting positions at a base, crossing over to three mounting positions at the ultrasound and/or shockwave source. Each connection of a linear actuator to either the base or the ultrasound and/or shockwave source may include a universal joint, also called a cardan joint or a ball joint. By variation of the length of the linear actuators, the ultrasound and/or shockwave source can be moved in six degrees of freedom with respect to the base. There are three degrees of translation and three degrees of rotation. Although the use of six linear actuators is preferred, a lower number of actuators may be used, e.g., like in a delta robot with three actuators.

The hexapod drive allows to adjust the position of an ultrasound and/or shockwave source relative to a patient's body and/or the X-ray system. Positioning of the ultrasound and/or shockwave source may be done automatically or by manual control. An automatic control may allow quick adjustment and it may also allow to store and retrieve preconfigured settings.

Such a hexapod drive is a very robust and mechanical stiff support or suspension of the ultrasound and/or shockwave source. Therefore, it can withstand high forces from the patient body, the weight of the ultrasound and/or shockwave source and dynamic loads which occur when shockwave pulses are generated. Further, a hexapod drive can be moved quickly. Therefore, a stable positioning of the ultrasound and/or shockwave source is achieved providing the additional ability to quickly correct deviations and movements by the patient.

A hexapod drive may allow movement in all <NUM> degrees of freedom. This allows for a precise adjustment of the position of the focal volume of the ultrasound and/or shockwave source and/or the path of the ultrasound and/or shockwave though the body of the patient.

The patient table may have a basically planar surface defining a longitudinal axis. It is configured for accommodating a patient. The ultrasound and/or shockwave source may be mounted below the patient table. In general, a shockwave source may be mounted in alternative ways, e.g., on a stand or support.

The base may be standing on a floor directly or by a stand or it may be attached to a floor. The base may also hold the table.

A method of aligning an ultrasound and/or shockwave source with an X-ray system includes the steps of:.

If the axes are not aligned and the displacement of axes is above a limit value, the steps c), d) and e) may be repeated multiple times until the displacement of axes is below a limit value.

The X-ray system, the ultrasound and/or shockwave source are oriented in a cartesian coordinate system as defined above.

In <FIG>, a first embodiment of a lithotripsy system, known from <CIT>, is shown. The invention works with any ultrasound and/or shockwave treatment system.

An extra-corporeal ultrasound and/or shockwave lithotripsy system for non-invasive treatment of stones <NUM> comprises a patient table <NUM>, an ultra-sound and/or shockwave source <NUM>. The ultrasound and/or shockwave source <NUM> is mounted to a hexapod drive <NUM>. The hexapod drive <NUM> may further be held by a stand <NUM>. The hexapod drive <NUM> allows fine positioning of the ultrasound and/or shockwave source <NUM> in multiple axes relative to the patient table <NUM> and therefore relative to the patient (not shown in this figure). The ultrasound and/or shockwave source <NUM> has a focal volume which moves together with the source. In an embodiment the distance of the focal volume to the source may be modified.

The patient table <NUM> is based on a stand <NUM> which may stand on a floor. The table <NUM> may be held by a positioning device <NUM> to move the table relative to the ultrasound and/or shockwave source <NUM> together with the hexapod drive <NUM>. A movement of the patient table may be coarse positioning which may be limited to a displacement in <NUM> axes.

The table <NUM> may have a flat surface for accommodating a patient who is not shown here.

An X-ray device <NUM>, acting as targeting device, may be provided. It may have an X-ray tube <NUM> opposing an X-ray detector <NUM>, both mounted tiltable at a C-arm <NUM>. There is a common center axis <NUM> on which the X-ray device and the ultra-sound and/or shockwave source are aligned.

To describe the relative movement of the table <NUM>, the X-ray device <NUM> and the ultrasound and/or shockwave source <NUM>, a cartesian coordinate system <NUM> may be used. There is a y-axis <NUM>, which may be a longitudinal axis through the center of the table. Furthermore, there is an x-axis <NUM> orthogonal to the y-axis and in the plane of the table surface. A z-axis <NUM> is orthogonal to the plane of the table surface and therefore orthogonal to the x-axis and the y-axis. There may also be a first rotation <NUM> around the x-axis, a second rotation <NUM> and a third rotation <NUM> around the z-axis. A positive rotation may be a clockwise rotation in a view along a positive axis.

A hexapod drive <NUM> may allow movement in all these <NUM> degrees of freedom. This allows for a precise adjustment of the position of the focal volume of the ultra-sound and/or shockwave source <NUM>. The patient table may be positioned for a slow and coarse adjustment in <NUM> degrees of translation for larger distances, but normally no rotation, whereas the hexapod drive provides a comparatively quick adjustment in <NUM> degrees of translation and <NUM> degrees of rotation. The movement distances of the table may be larger than the movement distances of the hexapod drive. The X-ray device may at least be tiltable to perform a second rotation <NUM> around an axis parallel to the y-axis <NUM>. It may also be tiltable around an axis parallel to the Y axis. It may further be translated in a plane defined by the X and Y axis. This means, it may be moved on the floor which is also in the X-Y plane.

For control of the movement of the ultrasound and/or shockwave source <NUM> relative to the patient table <NUM>, a control panel <NUM> may be provided.

<FIG> shows a more schematic perspective view of an ultrasound and/or shockwave source <NUM> mounted to a hexapod drive <NUM>. A shock wave or ultra-sound device, which may be a lithotripter <NUM> may include a patient table <NUM> and an ultrasound and/or shockwave source <NUM>. The ultrasound and/or shockwave source <NUM> may be arranged below the patient table <NUM>, such that a patient (not shown here) may be accommodated on top of the patient table. The patient table may have a longitudinal axis <NUM>. There may be a hole or cutout in the patient table at the position of the ultrasound and/or shockwave source.

The ultrasound and/or shockwave source <NUM> is supported by and/or suspended on a hexapod drive <NUM>. Basically, it is a type of parallel manipulator or parallel robot that has six linear actuators <NUM> - <NUM>, which may be hydraulic or pneumatic jacks or electric linear actuators. These linear actuators are connected in pairs to three mounting positions <NUM>, <NUM>, <NUM> at a base <NUM>, crossing over to three mounting positions <NUM>, <NUM>, <NUM> at the ultrasound and/or shockwave source <NUM>. Each connection of a linear actuator to either the base or the ultra-sound and/or shockwave source may include a universal joint, also called a cardan joint or a ball joint. By variation of the length of the linear actuators, the ultrasound and/or shockwave source can be moved in six degrees of freedom with respect to the base. There are three degrees of translation, parallel to at least one X-axis <NUM>, Y-axis <NUM>, Z-axis <NUM> and three degrees of tilt or rotation including a first tilt <NUM> around an axis parallel to X-axis <NUM>, a second tilt <NUM> around an axis parallel to Y-axis <NUM>, a third tilt <NUM> around an axis parallel to Z-axis <NUM>.

Further, the ultrasound and/or shockwave source <NUM> may have a center axis <NUM>.

<FIG> shows an embodiment in a side view. In this figure, a patient <NUM> is positioned on top of the patient table <NUM>. The patient may have a kidney <NUM> with a kidney stone <NUM>. An X-ray system includes an X-ray tube <NUM> shown below the patient and an X-ray detector <NUM> shown above the patient, both connected and held by a C-arm <NUM>. Here, the X-ray system is aligned with the shock wave generator <NUM> such that both are on the axis <NUM>. The X-ray system may further include a C-arm drive <NUM>, which may be an electrical motor with a gear.

A system controller controls at least operation of the X-ray system <NUM>, of the C-arm by means a C-arm control <NUM> and of the hexapod drive <NUM> by means of a hexapod control <NUM>. The system controller may also control the X-ray tube <NUM> and may receive images from the X-ray detector <NUM>.

Below the table <NUM>, the ultrasound and/or shockwave source <NUM> is shown in a sectional view. It may have a shock wave generator <NUM> which may be a coil as shown herein and which is at least partially enclosed by a reflector <NUM>. Further, the center axis <NUM> is marked as a dashed line. Normally, the interior of the reflector and the space between the source and the patient is filled with a liquid like water or another shockwave conducting medium. To contain the water within the volume, a coupling cushion <NUM> may be provided.

<FIG> shows a flow diagram of a method of aligning an ultrasound and/or shockwave source <NUM> with an X-ray system. The method utilizes a focal phantom including a first X-ray absorbing object <NUM> and a second X-ray absorbing object <NUM> arranged distant from each other at the axis of the ultrasound and/or shockwave source <NUM>. The method including the steps of:.

Steps <NUM> to <NUM> may be repeated multiple times until the offset between the images may be within a predefined limit or further iterations do not reduce the offset.

<FIG> shows a sketch of a focal phantom. An ultrasound and/or shockwave source <NUM> may have a first X-ray absorbing object <NUM> and a second X-ray absorbing object <NUM> distant in z-direction from each other. Both X-ray absorbing objects may be arranged symmetrical to the center axis of the source. Both X-ray absorbing objects may have different sizes and a symmetrical structure. They may be rings of different diameters. The first X-ray absorbing object <NUM> and a second X-ray absorbing object <NUM> may be removable from the ultrasound and/or shockwave source <NUM>.

In this embodiment, a shock wave source having a centered cylindrical coil <NUM> within a reflector <NUM> is shown. The first X-ray absorbing object <NUM> may be at one end of the coil, where the second X-ray absorbing object <NUM> may be at the other side thereof. An X-ray beam <NUM> from X-ray tube <NUM> passes through the source <NUM> and produces images of the Y-ray absorbing objects at the detector. The axis of the ultrasound and/or shockwave source <NUM> may be moved by the hexapod drive <NUM> until the images of both X-ray absorbing objects are centered. In this case, the source <NUM> and the X-ray system <NUM> are on the same axis.

<FIG> show X-ray images made with the procedure steps as explained in <FIG> with a focal phantom of <FIG>. Here, <FIG> shows an X-ray image as made in step <NUM>. It may show an X-ray image <NUM> of first X-ray absorbing object <NUM> and an X-ray image <NUM> of second X-ray absorbing object <NUM>. If the axis of the X-ray system <NUM> is not aligned with the axis of the ultrasound and/or shockwave source <NUM>, the objects are not centered. In step <NUM> the center <NUM> of X-ray image of first X-ray absorbing object and the center <NUM> of X-ray image of second X-ray absorbing object are determined. <FIG> shows the image taken in step <NUM> with calculated centers from step <NUM>, which overlap, as in this example the axis may be aligned. If the axes are still not aligned, then the centers would not be at the same position. In this case another iteration may be made.

Claim 1:
A shock wave and/or ultrasound therapy system (<NUM>) comprising an ultra-sound and/or shockwave source (<NUM>) and an X-ray system (<NUM>),
characterized in that
the ultrasound and/or shockwave source (<NUM>) is suspended on a hexapod drive (<NUM>), and a system controller (<NUM>) is provided and configured to generate control signals for the hexapod drive (<NUM>) to align the ultrasound and/or shockwave source (<NUM>) with the X-ray system (<NUM>).