RELATED APPLICATIONS

This application is the U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2018/055050, filed on Mar. 1, 2018, which claims the benefit of European Application No. 17158732.2, filed Mar. 1, 2017. This application is hereby incorporated by reference herein.

FIELD OF THE INVENTION

This invention relates to an ultrasound probe arrangement, in particular an ultrasound probe and a positioning system which enables the position of the probe to be adjusted relative to a surface to which the probe is being applied.

BACKGROUND OF THE INVENTION

Ultrasound probes can be used for imaging or other monitoring procedures, for example during minimally invasive cardiac interventions.

Ultrasound may be used during minimal invasive interventions in the heart, for example during heart valve repairs. This type of procedure is time consuming and it is important to have a stable image of the relevant part of the patient's body for a long period of time. Clinicians typically have to control the probes manually, for example passing the probe over the surface of the body by hand.

With regard to such a manual process, some applications use X-ray imaging/radiation together with ultrasound imaging. By holding the probe manually, the hand of the clinician is exposed to the harmful X-ray radiation. During long-term procedures, holding the ultrasound probe in a steady position is also difficult and strenuous for the clinician.

It is also known during ultrasound-guided procedures to make use of a probe positioning device, which holds the ultrasonic probe. The probe positioning device holds the probe at a predetermined position relative to the patient. The operation of these systems varies from completely manual, to completely automated.

In an automated probe positioning system, a control system corrects for the movement of the patient or disturbances in the environment. These systems can use a tilt, pressure or other sensor carried by the probe to collect positional data. The positioning system, such as a robotic arm, is coupled to the probe. The positioning system can provide roll and pitch control as well as translating the probe in lateral and longitudinal directions. A processor receives signals from the sensors corresponding to the actual orientation of the probe and controls the positioning system to adjust the orientation of the probe until the desired position is achieved.

This approach enables recording of the position of the ultrasound probe, for example so that the spatial relationship between multiple images can be derived. However, lower cost probe positioning systems which are not fully automated do not do not provide a convenient way of recording position information.

The use of a probe positioning system gives a more stabilized control compared to a hand held approach, giving reduced image distortion.

The current methods, whether fully manual or fully automated, are costly, take up valuable space around the patient, and in some circumstances may still lead to difficulties in providing a stable image. A steady image is particularly important for ultrasound-guided procedures.

U.S. Pat. No. 5,598,845 discloses a transducer device in which the transducer is mounted inside a spherical enclosure, and the spherical enclosure fits within a ring which is attached to the skin. This enables adjustment of the orientation of the transducer. The spherical enclosure has to be designed specifically for the ultrasound probe, which is attached to the inside walls of the enclosure.

SUMMARY OF THE INVENTION

The invention is defined by the claims.

According to examples, there is provided an ultrasound probe arrangement, comprising:

a holder for application to a surface;

a housing mounted over the holder, the housing having an inner guide surface which comprises a portion of a sphere;

a probe carrier comprising a disc having an outer guide surface around the outer rim of the disc which comprises a portion of sphere, wherein the probe carrier is slidable within the housing with the inner and outer guide surfaces in contact; and

an ultrasound probe can be carried by the probe carrier and which projects below the probe carrier towards the surface for making direct contact with the surface.

In particular, in accordance with examples in accordance with a first aspect of the invention, there is provided an ultrasound probe arrangement, comprising:

a holder (10) for application to a surface;

a housing (14) mounted over the holder, the housing having an inner guide surface (16) which comprises a portion of a sphere;

a probe carrier (18) comprising a disc having an outer guide surface around the outer rim of the disc which comprises a portion of a sphere, wherein the probe carrier (18) is slidable within the housing (14) with the inner and outer guide surfaces in sliding contact, wherein

the arrangement is configured such that a probe may be mounted in the carrier in a position such that a point of rotation of the probe caused by sliding of the probe carrier within the housing corresponds to a point of contact of a tip of the probe with the surface.

The holder, housing and probe carrier together function as a positioning system. They enable the probe to be held in a desired orientation so that a clinician can work hands-free. This means that blocking of X-ray imaging/radiation equipment around the patient is avoided. A small form factor also means there is also less blocking of other medical equipment around the patient. An additional benefit of the present invention is that an ultrasound transducer array, which is housed within the probe's tip, is arranged to be in a secured contact with the surface of the patient's body. This permits the transducer array to assure an efficient ultrasound wave transmission into and from the body.

The disc is designed for a specific probe design. By projecting the probe below the disc (by which is meant towards the surface compared to the disc) it may make direct contact with the skin. This means that a single contact point with the skin may be maintained during adjustment of the probe position.

The positioning system as a whole enables easy and intuitive use. By using a positioning system, the ultrasound probe is more stabilized compared to the situation where it is held by hand. Hence, the positioning system results in reduced image distortion. The holder can be sterilized before it is applied to the surface. For some applications, a hand held ultrasound probe was previously considered impractical because of the invasion of the sterile field by the hand of the sonographer. Multiple ultrasound probes can be placed on the surface by using several positioning systems. This does not require more operators as would be the case for hand held ultrasound probes.

The overall positioning system is attached to the surface and is not connected to the fixed world. This reduces the distortions that can act on the ultrasound probe and hence on the resulting images. For example, the positioning system will move in the same manner as the movements of the patient.

The arrangement provides easy fixation of orientation angles: once the desired orientation is achieved by the clinician (sonographer), the probe orientation is maintained after the clinician's hand is released, as a result of the friction between the two guide surfaces. For example, no screw tightening is needed.

The arrangement can be used with a miniaturized probe to reduce the overall size and hence become less obtrusive.

The housing may comprise a disc, the disc having said inner guide surface which comprises a portion of a sphere, i.e. the housing may be in the form of a disc. The disc may be a generally cylindrical or tubular-shape disc.

By providing the housing in the form of a disc, a particularly compact and flat arrangement is provided which is convenient when performing ultrasound examination.

The outer guide surface around the outer rim of the disc preferably comprises a portion of a sphere shaped to engage flush with the inner guide surface.

The inner guide surface preferably comprises a continuous portion of a sphere.

The arrangement is configured such that a probe may be mounted in the carrier in a position such that a point of rotation of the probe corresponds to a point of contact of a tip of the probe with the surface. The point of rotation means a center of rotation of the probe; the point about which the probe rotates by means of sliding within the housing. By making the center of rotation a point of contact with the surface, the angular orientation of the probe relative to the surface can be varied without translating the probe (namely transducer array) across the surface, which can introduce motion distortions in generated imagery and measurements.

The probe is preferably positioned to make contact with the surface at a location corresponding to the center of the sphere. This is one means of ensuring that the point of rotation corresponds to the location of the tip of the probe against the surface.

This central location does not shift laterally in response to adjustment of the probe orientation angle, so that the position on the surface remains constant during adjustment.

Existing probe holders do not have the rotation point of the probe on the skin. This introduces a translation when re-adjusting the probe rotation.

The center of the sphere may mean the center of the sphere of which the inner guide surface is a portion or the sphere of which the outer guide surface is a portion. Since the two surfaces preferably engage flush with one another, these two spheres may be considered one and the same.

The outer guide surface is a surface around the outer rim of a disc. This arrangement provides superior maneuverability and control compared other arrangements. In particular, a large degree of rotational freedom is possible and the arrangement also allows the carrier to be held fixed in any orientational position merely through frictional contact with the housing surface which occurs upon pressing of the probe against the skin.

The outer guide surface around the outer rim of the disc may in particular be a radially outermost surface of the outer rim of the disc.

The portion of a sphere of the inner guide surface may be a spherical segment, i.e. the inner guide surface may comprise a portion of a sphere in the form of a spherical segment.

Spherical segment is a geometric term. It means the solid defined by cutting a sphere with a pair of parallel planes. It can be thought of as a spherical cap with the top truncated; it corresponds to a spherical frustum.

By providing the inner guide surface as a spherical segment, with the carrier comprising a disk shaped to engage slidingly with the inner surface of said segment, there is provided two dimensions of rotational freedom for the carrier, with the central annulus of the spherical segment providing an access point via which the carrier can be so rotationally manipulated.

Where the inner guide surface comprises a spherical segment, the portion of a sphere of the outer guide surface may be a spherical sub-segment of said spherical segment, i.e. a spherical segment forming a portion of said spherical segment of the inner guide surface. This ensures a large degree of rotational freedom in two dimensions about the inner surface of the housing.

The housing preferably has an adjustable position in the holder. This adjustable position enables a pressing force to be adjusted. This is for example needed for cardiac ultrasound to enable good probe positioning between the ribs.

The holder and the housing may together form a ratchet arrangement. In this way, the housing can be pushed into the holder (i.e. towards the surface), until a desired position is reached. This desired position corresponds to a particular pressing force, in that the surface provides a reaction force which depends on the amount of depression. The housing is then held in position by the ratchet arrangement. The ratchet arrangement can be released to subsequently decouple the housing and holder.

The adjustable position may comprise a set of discrete positions, wherein each discrete position allows for a limited amount of relative movement between the holder and the housing. In this way, there is some normal (i.e. perpendicular to the surface) movement allowed. When adjusting the probe carrier and probe orientation, the lateral contact position is preferably fixed but the height will vary. The allowed relative movement takes up this height variation.

The arrangement may further comprise an adhesive component for attaching the holder to the surface. In this way, the holder may be fixed in position before applying the probe.

The arrangement may further comprise a position sensor arrangement for sensing the relative position of the housing and the probe carrier.

In this way, the positioning system can track the orientation angles of the ultrasound probe. This information can be used for distortion detection and image registration.

The position sensor arrangement for example comprises a light source and a light detector provided at one of the housing and the probe carrier, and a detectable image on the other of the probe carrier and the housing. By reading the image (by monitoring reflected light), a local image portion may be recognized and identified, and this local portion encodes location information. Alternative positioning systems are possible such as gyroscopes and/or acceleration sensors and/or magnetic sensors.

The image may for example comprise a dot pattern, wherein the local dot pattern at any location of the image identifies that location. This provides a positioning system which is simple to implement.

The image may be provided on the inner guide surface and the light source and light detector are provided on the probe carrier.

The arrangement is preferably an ultrasound imaging probe.

Examples in accordance with another aspect of the invention provide a method of adjusting the positon of an ultrasound probe, comprising:

applying a holder (10) to a surface;

mounting a housing (14) over the holder, the housing having an inner guide surface (16) which comprises a portion of a sphere;

supporting an ultrasound probe (24) on a probe carrier (18) comprising a disc having an outer guide surface which comprises a portion of sphere, wherein the probe carrier is slidable within the housing with the inner and outer guide surfaces in sliding contact, wherein the ultrasound probe (24) projects below the probe carrier to make direct contact with the surface, and wherein the probe carrier and housing are configured such a point of rotation of the probe caused by sliding of the probe carrier within the housing corresponds to a point of contact of a tip of the probe with the surface; and

adjusting the position of the ultrasound probe by moving the probe carrier within the housing, wherein the probe projects from the probe carrier towards the surface.

The position of the holder over the housing may also be adjusted.

The method may further comprise making contact between the ultrasound probe and the surface at a location corresponding to the center of the sphere.

