Articulated x-ray support boom using jammable material

An x-ray head support boom has a number of tube segments coupled together in series. Each segment may be formed from a flexible membrane and encloses a jammable medium that transitions between a fluidic state and a rigid state in response to an applied force. Each segment is coupled to an actuator for application of the force. At least one cable is coupled to one or more tube segments to apply a tensile force to bend the series of tube segments.

FIELD OF THE INVENTION

The present disclosure relates generally to radiographic imaging apparatus and more particularly to a support boom for an x-ray head.

BACKGROUND OF THE INVENTION

The x-ray head for a radiographic imaging apparatus is generally supported on some type of boom that allows the head to be properly positioned with respect to the subject being imaged and to the imaging detector. The x-ray head contains the emissive x-ray source and typically also has a number of related components that can include a collimator, controls, and guiding handles, for example. X-ray boom design is complicated by a number of factors, including the combined weight of the x-ray source and supporting components, the need to be able to flexibly position the head with the necessary rotational and translational degrees of freedom, and the requirement that the head position be stably maintained during setup and imaging procedures.

Supporting the boom for the x-ray head presents a particular challenge for mobile x-ray apparatus. Unlike conventional wall- and ceiling-mounted x-ray systems, mobile x-ray apparatus can be wheeled around the ICU or other area and brought directly to the patient's bedside. In these circumstances, the operating space for maneuvering the boom and x-ray head (for example, within the narrow space between patient beds) restricts the clinician's ability to quickly and accurately position the device for x-ray acquisition. In addition, the added weight and complexity of the head support boom and its associated hardware are factors that can add to the cost of these devices and complicate their operation and maintenance requirements. For example, where the x-ray head is mounted with a cantilevered arrangement, sufficient counterbalance mechanisms and ballast are required in the mobile x-ray cart base to allow movement by the clinician or technician. This tends to increase the overall weight of the mobile x-ray apparatus, thereby requiring more complex automated drive and steering mechanisms. These requirements, in turn, tend to increase product cost and complexity, with added risk factors related to unintended system motion.

Mobile apparatus designs in commercial use are characterized by complex, cantilevered boom designs with fixed or collapsible columns and the need for substantial counterweights, numerous supporting actuators, and fixed movement paths between spatial locations, often constrained by the mechanical design of boom components.

One concern that must be addressed in design of the support member relates to ease of positioning of the x-ray source mounted on its boom. For ease of operation under varying conditions, the technician should be able to easily position and orient the x-ray source without requiring both hands, without the need of additional tools, and without needing help from nearby personnel. This includes moving the x-ray source from its docked position used in transport to an imaging position. The mechanical problem of providing ease of positioning is complicated by the weight of the x-ray source and by its extension outward from the vertical axis.

Thus, there is a need for an x-ray head support boom that offers reduced weight, reduced parts count, and relative ease of use by the attending technician, particularly in confined areas, both for stationary x-ray systems and mobile x-ray apparatus.

SUMMARY OF THE INVENTION

An object of the present invention is to advance the art of radiography. A related object of the present invention is to address the need for a mobile radiography unit that allows ease of movement of the boom assembly between various positions.

From one aspect, the present invention provides an x-ray head support boom comprising a plurality of tube segments, coupled together in series, each segment formed from a flexible membrane and enclosing a jammable medium that transitions between a fluidic state and a rigid state in response to an applied force, each segment coupled to an actuator for application of the force that changes the jammable medium between states, at least one cable coupled to one or more tube segments, and a first motor applying a tensile force to the at least one cable wherein the tensile force bends the one or more tube segments.

DETAILED DESCRIPTION OF THE INVENTION

The following is a detailed description of the preferred embodiments of the disclosure, reference being made to the drawings in which the same reference numerals identify the same elements of structure in each of the several figures.

Where they are used, the terms “first”, “second”, and so on, do not necessarily denote any ordinal or priority relation, but may be used for more clearly distinguishing one element or time interval from another.

Apparatus and methods of the present disclosure address the need for an x-ray head support boom that articulates to allow flexible positioning of an x-ray head. The x-ray head support boom of the present disclosure can be particularly suitable for a mobile radiography apparatus, but can similarly be used with a stationary x-ray system, such as a wall-mounted or ceiling-mounted system. The support boom can also be used for support of a C-arm or other mount that supports the x-ray head and related components.

The perspective views ofFIGS. 1A, 1B, and 1Cshow a mobile radiography apparatus100that has a movable cart20that can be wheeled from one location to another, such as within an intensive care unit (ICU) or other department or facility. An x-ray head10is coupled to the end of a flexible tube30that provides at least a portion of an articulated x-ray head support boom40for positioning x-ray head10for imaging.FIG. 1Ashows boom40in a flexible or contracted configuration. X-ray head10can be seated on a shelf or bracket12of cart20, such as for ease of transport between use sites.FIG. 1Bshows boom40in an extended, rigid configuration for imaging use.

FIG. 1Cshows boom40as an articulated structure allowing head10movement between two locations, shown as A and A′ in this example. In theFIG. 1Cembodiment, articulated boom40uses both a rigid metal boom and flexible boom portions.

The perspective view ofFIG. 2shows a stationary x-ray apparatus50that has an articulated support boom40using tube30to allow adjustable x-ray head10positioning.

The schematic view ofFIG. 3shows components not shown in previous figures for providing an exemplary support boom40that extends horizontally. Support boom40is formed as a tube30from a number of modular tube segments42, coupled together in series. Each tube segment42is formed from a flexible medium, such as a plastic or other flexible material. According to an embodiment, the material that is used is impermeable to gas or liquid, so that segment42is capable of maintaining an internal pressure or vacuum that, in turn, controls a variable rigidity for each segment42. Each segment42has a corresponding pressure control conduit44connected to a pump46that provides a vacuum or pressure source through a valve14that serves as an actuator for movement of air or other gas or liquid used as a force for the jamming mechanism that provides rigidity of the jamming medium as described in more detail subsequently.

Still referring toFIG. 3, one or more cables62, each driven from a motor60, are provided for providing tensile force along a direction. The applied urging force of a cable62can cause corresponding motion of one or more segments42. The urging force of cable62can also bend the boom40by imparting a variable arcuate shape to the tube30. The combination of variable rigidity and cable actuation and tension allows support boom40to assume a given shape or curvature and rigidity for urging movement between positions and supporting x-ray head10once it is in position. A control logic processor70, such as a computer or a microprocessor or other dedicated processor, in signal communication with motor and actuator components and an optional display, can be used to control boom operation. Similar components can be used for a boom that extends vertically.

FIGS. 4A and 4Bare schematic diagrams that show how variable rigidity for each tube segment42of boom40can be controlled. AsFIG. 4Ashows, each segment42, formed from a flexible membrane, acts as a pressurizable envelope containing a jammable granular medium66. Granular medium66is termed “jammable” because it effects a mechanical phase change with a change in atmospheric pressure or other applied force, such as liquid flow velocity or vibration, at levels beyond a given threshold.

According to an embodiment of the present disclosure, vacuum is used as the applied force to stiffen granular medium66.FIG. 4Bshows medium66in its jammed state, with vacuum force applied to segment42. In this state, granular medium66aligns or is otherwise arranged to transform the stiffness of segment42from a more flaccid, non-rigid, or relaxed state shown inFIG. 4Ato the rigid state shown inFIG. 4B. By controlling the amount of vacuum, pump46ofFIG. 3can control the individual rigidity of each segment42of boom40. This not only allows boom40to have a variable length of extension within a range, it also allows boom40to have various shapes in the stiffened state, such as the arcuate shape shown inFIG. 1BandFIG. 2, or the relatively linear shape shown inFIG. 1CandFIG. 3.

Individual segments42can be configured to be extendable and contractible in a telescoping configuration. Individual segments42used to form tube30can be of different diameters and lengths, depending on support requirements. Thus, for example, boom40can be thicker near its base and be tapered to have reduced diameter near the x-ray head10. Segments42can also have pre-set bends if needed, such as to condition the tube30for bending to particular storage or positioning configurations.

An alternative method of actuation applies positive pressure to the various segments in order to enable boom movement between head positions. In this method, the granular medium is jammed (i.e. compressed) in the free state (that is, with no external pressure applied). Positive pressure expands the volume of the flexible membrane segment(s) thereby reducing the friction of the jamming medium. This method would provide a fail-safe method of operation should the system lose power or pressure. In this instance, the un-actuated system would “lock” in its current configuration, retaining the x-ray head at its current position. This would prevent unintended motion that could otherwise present a hazardous condition for the technician, patient, or nearby persons.

Segments42can be formed in a number of ways. According to an embodiment, individual segments42are fabricated from suitable materials, fitted with valve actuator and jammable media contents, then joined together serially to provide boom40. Segments42may be sewn together or otherwise fastened together, for example. Jammable media materials may be provided within one or more channels, individual pockets, or smaller envelopes within segment42, or may be used to at least partially fill a single large cavity. Segments42can optionally include stiffeners, such as internal or external coils for retaining some amount of stiffness when the jammable medium is in the un-jammed, relaxed, or flaccid state.

FIG. 5Ais a cross-sectional view of a portion of a support boom that has internal tubing and cable actuation routed to the individual tubing segments42within a hollow annulus that provides an internal channel64.FIG. 5Bshows a schematic diagram of a single tubing segment42from a perspective view. Conduit44extends through channel64and directs air or other fluid into, or out from, the medium66to change between more rigid and more relaxed or fluidic states as described with reference toFIGS. 4A and 4B. A valve14within channel64is actuated between open and closed positions according to signals from control logic processor70. Cable62extends from motor60to each segment42through the channel provided by internal channel64.

Jammable or Stiffness Phase-Change Materials

Embodiments of the present disclosure use a boom that is configured to adopt a particular shape and position by using a reversible process that employs jammable media. A jammable medium changes from a fluidic state to a rigid state in response to an applied force or stimulus.

Various types of reversibly jammable materials have been used for conformable manipulators and other devices. These materials are also termed phase change materials or stiffness phase change materials because they change from a loose, fluidic state under one set of conditions, then become stiff or rigid under a different set of conditions. Jammable granular materials suited for use under variable vacuum levels include hollow and solid glass beads of given dimensions, ground coffee, diatomaceous earth, and sawdust, for example. Each of these types of granular materials enables the reversible process for variable rigidity or fluidity according to vacuum level.

Other types of stiffness phase change materials can be used, including materials that provide a reversible stiffness under different conditions. A material that jams when pressure is applied or due to changes in fluid flow conditions can be used, for example. According to an alternate embodiment of the present disclosure, behavior that is opposite to that described with reference toFIGS. 4A and 4Bis used. Jammable material is packed tightly within a segment42envelope so that the segment is rigid under ambient pressure conditions. To reduce stiffness for boom movement, pressure is applied to the segment; this applied force effectively increases the volume of the jammed envelope. As a result of increased air pressure, or other fluid pressure, the jammed material is momentarily un-jammed, reducing rigidity to allow movement. A material that is jammed under normal atmospheric pressure but un-jams when pressure exceeds a threshold can alternately be used.

Still other approaches use different force mechanisms to effect a reversible jamming response. One mechanism uses dilatants that exhibit a variable viscosity that increases with the rate of shear. A dilatant (also called shear thickening) material is one in which viscosity increases with the rate of shear. The dilatant effect is believed to occur when closely-packed particles are combined with enough liquid to fill the gaps between them. At low velocities, the liquid acts as a lubricant, and the dilatant flows easily. With the liquid forced through the medium at higher velocities, the liquid is unable to fill the gaps created between particles, and friction greatly increases, causing an increase in viscosity.

One such dilatant material is a combination of cornstarch and water, that can be made to stiffen in response to vibration. A piezoelectric motor or other vibration source can be used as an actuator to provide the needed force for changing material rigidity.

Other materials that, while not truly phase change materials, can be contemplated for use for a support boom using variable stiffness can include electrorheological (ER) fluids and magnetorheological (MR) fluids. ER fluids are suspensions of extremely fine non-conducting particles (up to, for example, 50 micrometers in diameter) in an electrically insulating fluid. The apparent viscosity of these fluids can change reversibly by an order of up to 100,000 in response to an electrical field. An MR fluid is a suspension of micrometer-sized magnetic particles in a carrier fluid, usually a type of oil. When subjected to a magnetic field, the fluid greatly increases its viscosity, to the point of becoming a viscoelastic solid. The yield stress of the fluid when in its active (on) state can be controlled very accurately by varying the magnetic field intensity.

It should be noted that the jammable material may or may not have intermediate states of progressively increasing rigidity. Pressure or vacuum above or below a particular threshold, for example, may lock media granules into position or free them from an ordered arrangement in a binary manner, so that the jammable material is either highly rigid or substantially fluidic. For other materials, rigidity can be proportional to the jamming or un-jamming force that is applied.

Positioning Options

Embodiments of x-ray head support boom40allow the technician to position the x-ray head in a flexible manner, adjusting and relaxing boom stiffness as needed by adjustable rigidity of segments42and allowing tube30to have various arcuate shapes for obtaining the desired position.

Using the boom of the present disclosure, articulated support boom40can be used to position x-ray head in a number of ways. Manual positioning of x-ray head10can be performed by the technician by an instruction or movement that causes x-ray system logic to sense repositioning movement by the technician and to respond by releasing and applying variable stiffness or rigidity to various segments in order to achieve a given position.

FIG. 6shows, in schematic form, how support boom40can be moved by a technician from one position to another. Positions in this incremental movement sequence are labeled A, B, and C in this figure. The technician provides some type of instruction that energizes boom40for movement, such as by entering a keyboard command on a control console or by command entry at x-ray head10, for example. Feedback sensing, using one or more sensors24, can detect pushing or pulling force exerted by the technician in order to change boom40position. In a coordinated sequence, executed by control logic processor70(FIGS. 3 and 5A), individual segments42are adjusted to provide various levels of rigidity during movement, allowing head10to be turned and re-oriented. Rigidity changes can be momentary, allowing enough time for incremental shifting and adjustment of boom orientation and curvature as well as head10position. Full rigidity is restored at different points in the movement cycle, allowing support of the x-ray head10weight as the head10is moved from one position to another.

FIG. 7is an exemplary timing diagram showing variable rigidity for one segment42dof the x-ray support boom40for the movement sequence shown inFIG. 6. Rigidity for a segment is represented on a scale from0to1with higher rigidity assigned higher values. Fully rigid in the A position, a momentary drop in rigidity for segment42dis needed in order to transition toward the B position. For continued movement to the C position, rigidity of segment42dmust be relaxed even further, until the desired position is achieved. Once movement is completed, segment42dis returned to a fully rigid state. It should be noted that adjustment changes are also applied for the other segments42in boom40, with timing and rigidity differences as needed to support the movement sequence. Sensors24are arranged along boom40in order to detect characteristics such as angular orientation, pressure, proximity, and other parameters that indicate how the rigidity for individual segments42must be adjusted.

Automated coarse positioning of boom40can also be provided. Referring toFIG. 8, there is shown a control screen display80for coarse positioning of the x-ray head support boom. Display80with this function may be provided as part of cart20, as shown inFIG. 1B. The technician enters or selects an examination type, such as from a menu52, and provides information on the patient disposition (prone, standing) and other data for initial positioning in a data entry section54, then presses the Start instruction56. Alternately, a touch screen interface is used to position an icon of the head at the approximate position. The touch screen interface can present 3-dimensional (3-D) images of the cart20or boom40structures, enabling coarse positioning of the x-ray head10with 3-D manipulation. During or after screen positioning, the technician can then lift the head from a resting position, or from its current position, and use the coarse positioning instructions to assist in positioning the x-ray head. As the head is moved by the technician, sensing components of the radiography apparatus correspondingly adjust and relax the rigidity of different segments42in order to support continuous boom40movement from one point to another.

The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the scope of the invention as described above, and as noted in the appended claims, by a person of ordinary skill in the art without departing from the scope of the invention.