Patent Publication Number: US-2009227874-A1

Title: Holder assembly for a medical imaging instrument

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 60/986,866 entitled “Axis Alignment Method” and having a filing date of Nov. 9, 2007, the entire contents of which are incorporated herein by reference. 
    
    
     FIELD 
     The present invention is directed to system, apparatus and method for holding and positioning a medical imaging instrument. More particularly, the invention relates to an apparatus adapted to hold a medical imaging instrument such that the instrument may be positioned, secured and/or rotated about at least one fixed axis by a positioning device. 
     BACKGROUND 
     Doctors and other medical professionals often utilize medical imaging instruments to conduct non-invasive examinations. That is, medical imaging instruments, including X-ray, magnetic resonance (MR), computed tomography (CT), ultrasound, and various combinations of these instruments/techniques are utilized to provide images of internal patient structure for diagnostic purposes as well as for interventional procedures. These medical imaging instruments allow examination of internal tissue that is not readily examined during normal visual or tactile examination. Applications include imaging in the areas of urology, brachytherapy, cyrotherapy, photo-dynamic therapy, or a combination of these therapies and/or fusion-guided biopsies. 
     Medical imaging devices typically allow for generating three-dimensional (“3-D”) images of internal structures of interest. Such 3-D imaging may improve the accuracy and/or reliability of medical diagnosis. For instance, a medical imaging device may be utilized to generate a 3-D model or map of the prostate such that one or more biopsies may be taken from a desired location of the prostate. For purposes of prostrate imaging, a transrectal ultrasound-imaging device (e.g., a “TRUS probe” or “ultrasound probe”) may provide image acquisition and guidance. The ultrasound probe is a widely accepted technique for prostate applications due to its simplicity, high specificity, and real time nature. In such an application, the ultrasound probe or any other medical imaging device may be inserted into the rectum of a patient to generate an image. Such images may be utilized to take one or more biopsies from a prostate location of interest and/or implant radioactive seeds at one or more desired locations in a brachytherapy procedure. 
     In order to generate 3-D images, many medical imaging devices obtain a plurality of two-dimensional (“2-D”) images and combine these images together to form a 3-D image. Accordingly, movement of a medical imaging device between the acquisition of individual images makes it more difficult to properly align (e.g., register) the different images for purposes of generating accurate 3-D images. Thus, precise and repeatable placement and guidance of the medical imaging device is desirable to achieve accurate imaging and rendering of the applicable therapy. 
     Traditionally, a medical practitioner manipulates a medical imaging device by hand for medical image acquisition and/or treatment. That is, the medical practitioner manually guides the instrument. Such manual manipulation is suitable for many medical procedures. However, in instances where it is desirable to obtain multiple images for 3-D image generation, manual manipulation of the device may result in movement between images. Further, for biopsy and other treatment procedures it is desirable to know the relative location between an imaging instrument and a tissue area of interest. That is, it is important that the device directs an imaging field to a particular tissue location and remain stationary to allow for guiding a biopsy/treatment device to a tissue location within the imaging field. Relative movement between the imaging device and the tissue area of interest during imaging and/or biopsy/treatment may impede the successful performance of these procedures. 
     Accordingly, a number of probe holding and manipulating/positioning assemblies have been proposed. These assemblies generally involve a holder that interfaces with a medical imaging device such as an ultrasound probe. The holder is then interconnected to one or more mechanical armatures and/or actuators such that the probe may be mechanically positioned and/or rotated relative to an area of interest on a patient (a “positioning device”). While this approach is generally effective, a number original equipment manufactures (“OEMs”) produce handheld probes in the market (e.g., Asucon, Aloka, ATL, B&amp;K, Diasonics, General Electric, Hewlett Packard, Hitachi, Interspec, Philips, Siemens, Toshiba, etc.). While these probes do have some commonalities, they do not have a standardized design. Each probe generally has an acquisition or insertion portion and a handle portion. Typically, the acquisition portion is offset at an angle from the handle portion for ergonomic purposes. That said, probes produced by different manufactures feature acquisition portions and handle portions of differing lengths, widths, configurations, and offsets. Because limiting the rotation of the probe about an axis defined by the acquisition portion of the probe (an “acquisition axis”) removes a degree of freedom from subsequent calculations used to register a sequence of 2-D images together to form a 3-D image, the lack of conformity between probes has resulted in the need for specialized positioning devices for differently configured ultrasound probes. Accordingly, prior positioning devices have required that a medical facility utilize a particular probe with a particular specialized positioning device. 
     SUMMARY 
     The present invention provides systems and methods for interfacing variously configured medical imaging devices for imaging applications (e.g., TRUS probes or other ultrasound probes, biopsy needles, therapeutic devices, medical imaging devices, etc.) in a fixed positional relationship with a positioning device. Such positioning devices may be utilized to position medical imaging devices relative to a patient tissue of interest. Aspects of the present invention provide an apparatus for interfacing an ultrasound probe with such a positioning device. 
     The apparatus embodied by a first aspect includes a connector and a probe holder. The connector is adapted to be rotatively coupled to a positioning device such that the connector is operative to rotate relative to the positioning device about a rotational axis. The probe holder includes a recessed surface that is sized to receive and secure at least a portion of an ultrasound probe. In addition, the probe holder is coupled to the connector at a location that is spaced from the rotational axis, and as a result, the recessed surface is offset from the rotational axis. This offset may allow an acquisition portion of a probe placed in the recessed surface to be aligned with the rotational axis of the positioning device. 
     The connector may be coupled to both the positioning device and the probe holder in any appropriate manner that allows the connector, and thus the probe holder, to rotate about the rotational axis. For instance, the connector may be fixedly coupled to a mating shaft that is rotatively coupled to the positioning device so as to allow the positioning device to rotate the connector via the mating shaft. In addition, because the probe holder is coupled to the connector at a position that is spaced from the rotational axis, the probe holder may orbit the rotational axis when the positioning device is in operation. 
     In one arrangement, the apparatus may include an ultrasound probe disposed within the recessed surface of the probe holder. The ultrasound probe may have a handle portion that generally defines a handle axis and an acquisition portion that generally defines an acquisition axis. In some cases, the handle axis and the acquisition axis may be nonconcentric. However, when the handle portion is disposed and/or secured within the recessed surface, the rotational axis of the positioning device and the acquisition axis of the acquisition portion of the probe are substantially concentric. This concentric alignment allows the acquisition portion of the probe to rotate about the rotational axis substantially free of precession or wobble, which may provide for improved image registration. 
     In one arrangement, the recessed surface of the probe holder may be correspondingly shaped to the handle portion of the probe. When the recessed surface of a particular probe holder is correspondingly shaped to concentrically align a particular probe, different probes having different configurations may utilize different probe holders to interface with the positioning device. That is, each different probe may utilize a customized probe holder. 
     In another arrangement, the apparatus may include a flexible joint disposed between the connector and the probe holder. The flexible joint may permit the selective adjustment and/or alignment of the probe holder, and thus a secured probe, in relation to the rotational axis of the positioning device. That is, the flexible joint may allow for aligning an acquisition axis of the probe with the rotational axis of the positioning device. As a result, the flexible joint may allow for more general use of the probe holder, or allow for a single probe holder to be used with various probe configurations. 
     The flexible joint may include one or more rotational, revolving, gyratory, or other joints of any appropriate size, type, and/or configuration. For instance, the flexible joint may include one or more ball-and-socket joints, a ball-bar-socket joint, a binge joint, or any other appropriate joint that allows for adjustment within multiple degrees of freedom. 
     The apparatus may also include a locking mechanism adapted to lock the flexible joint in a desired position. For example, in one arrangement, one or more securement plates may be tightened about each ball-and-socket or other rotational joint so as to prevent further movement of the rotational joint. The securement plates may be tightened with threaded fasteners such as, for example, set screws, thumbscrews, cap screws, etc. 
     In another aspect of the present invention, an alignment fixture may be used to adjust a flexible joint of a probe holding apparatus to concentrically align a rotational axis of a positioning device with an acquisition axis of an ultrasound probe. In this aspect, the alignment fixture may include a base that supports a probe holding apparatus in a desired relationship to the rotational axis. In one arrangement, a connector of the apparatus may be fixedly positioned relative to the rotational axis, and a probe holder of the apparatus may then be adjusted. In such an arrangement, a probe holder may be coupled to the connecter via a flexible joint. The alignment fixture may also incorporate an indicator that provides an indication of the alignment of the acquisition axis of a probe disposed in the probe holder to the relational axis. For example, when an ultrasound probe is secured within the probe holder, a lever arm of such an indicator may engage the acquisition portion of the probe such that when the mating shaft rotates the probe, the indicator detects any precession in the acquisition portion of the probe. If precession is detected, the flexible joint may be adjusted until the acquisition portion of the probe rotates about the rotational axis substantially free of precession before the flexible joint is secured 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         FIG. 1A  shows a cross-sectional view of a trans-rectal ultrasound imaging system as applied to perform prostate imaging. 
         FIG. 1B  illustrates use of a positioning device to position an ultrasound imaging device to perform prostate imaging. 
         FIG. 2A  illustrates two-dimensional images generated by the trans-rectal ultrasound imaging system of  FIG. 1 . 
         FIG. 2B  illustrates a three-dimensional volume image generated from the two dimensional images of  FIG. 2A . 
         FIG. 3  illustrates a side plan view of one embodiment of an ultrasound probe. 
         FIG. 4  illustrates a perspective view of one embodiment of a holder assembly for securing an ultrasound probe. 
         FIG. 5  illustrates a perspective view of an ultrasound probe secured within the holder assembly of  FIG. 4 . 
         FIG. 6  illustrates another embodiment of a holder assembly for securing an ultrasound probe. 
         FIG. 7  illustrates a perspective view of an ultrasound probe secured within the holder assembly of  FIG. 6 . 
         FIG. 8  illustrates a perspective view of a portion of a flexible joint. 
         FIG. 9  illustrates another perspective view of a portion of a flexible joint. 
         FIG. 10  illustrates a perspective view of the holder assembly and secured ultrasound probe of  FIG. 7  as mounted within an alignment fixture. 
         FIG. 11  illustrates a detailed view of the biasing collar assemblies of the alignment fixture of  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION  
     Reference will now be made to the accompanying drawings, which assist in illustrating the various pertinent features of the present disclosure. Although the present disclosure is described primarily in conjunction with transrectal ultrasound imaging for prostate imaging, it should be expressly understood that aspects of the present invention may be applicable to other medical imaging applications. In this regard, the following description is presented for purposes of illustration and description. 
     Systems and methods are disclosed that facilitate obtaining medical images and/or performing medical procedures. One embodiment provides a medical imaging device holder (i.e., probe holder or holder) that has a recessed surface adapted to securely support a particular ultrasound probe for interfacing the ultrasound probe in a fixed positional relationship with a positioning device. Another embodiment provides a probe holder that allows for more general use of a single holder assembly that is capable of securely supporting a variety of different ultrasound probes in a desired positional relationship with a positioning device. The probe holders of the present invention may be interfaced with a positioning device such that the acquisition axis of the supported probe may be rotated about the rotational axis of the positioning device in a manner substantially free of precession or wobble. In this regard, the supported probe may obtain multiple images in different angular positions for 3-D image generation. Because the positioning device securely supports the probe, there may be little or no probe movement between successive images, other than rotation about the rotational axis. Accordingly, successive images may more easily be registered together. 
       FIG. 1A  illustrates a transrectal ultrasound probe being utilized to obtain a plurality of 2-D ultrasound images of the prostate  12 . As shown, the probe  10  may be operative to automatically scan an area of interest. In such an arrangement, a user may rotate the acquisition portion  14  of the ultrasound probe  10  over an area of interest. Accordingly, the probe  10  may acquire plurality of individual images while being rotated over the area of interest. See  FIGS. 2A-B . Each of these individual images may be represented as a 2-D image. See  FIG. 2A . Initially, such images may be in a polar coordinate system. In such an instance, it may be beneficial for processing to translate these images into a rectangular coordinate system. In any case, the 2-D images may be combined to generate a 3-D image. See  FIG. 1B . 
     As shown in  FIG. 1A , the ultrasound probe  10  is a side-fire probe that generates ultrasound waves out of the side surface. However, it will be appreciated that end-fire scan probe may be utilized as well. In any arrangement, the probe  10  may also include a biopsy gun (not shown) that may be attached to the probe. The biopsy gun may include a spring driven needle that is operative to obtain a core from desired area within the prostate. In this regard, it may be desirable to generate an image of the prostate  12  while the probe  10  remains positioned relative to the prostate. If there is little or no movement between acquisition of the images and generation of the 3D image, the biopsy gun may be positioned to obtain a biopsy (or perform other procedures) of an area of interest within the prostate  12 . However, manual manipulation of the probe  10  often results in relative movement between the probe and the prostate  12  between subsequent images and/or as a biopsy device is guided toward an area of interest. 
     Accordingly, it is desirable to minimize relative movement between the probe  10  and the prostrate  12  (i.e., precession, wobble or any other rotational movement of the probe about a fixed axis for image acquisition). It is also often desirable for probe  10  to remain fixed relative to the prostrate  12  during biopsy or other treatment procedures such that the desired tissue locations may be targeted accurately. To achieve such fixed positioning of probe  10 , it is often desirable to interface the probe  10  with a positioning device such as the exemplary positioning device  100  shown in  FIG. 1B . The positioning device  100  maintains the probe  10  in a fixed position relative to the prostate  12  and provides location information (e.g., frame of reference information) for use with an acquired image. In this regard, location outputs from the positioning device  100  may be supplied to a computer and/or imaging device. Likewise, the output of the probe  10  may be provided to the computer and/or imaging device, and the computer and/or imaging device may utilize this information to produce an output (e.g., display) of the imaged object (e.g., prostate). 
     The present invention may be used to interface an ultrasound probe with various positioning devices of the type discussed above. One exemplary positioning device is set forth in International Application Number PCT/CA2007/001076, entitled Apparatus for Guiding a Medical Tool. Another is set forth in U.S. application Ser. No. 11/850,482, entitled Tracker Holder Assembly, the contents of which are fully incorporated herein by reference. 
     In order to utilize the probe  10  with the positioning device  100  as illustrated in  FIG. 1B , it is necessary to secure the probe  10  to the positioning device. That is, there must be an interface between the probe  10  and the positioning device  100 . The fact that probes made by different probe manufacturers have different dimensions complicates the task of interfacing the ultrasound probe  10  with the positioning device  100 . For instance,  FIG. 3  illustrates an exemplary ultrasound probe  10 . In this embodiment, the probe  10  includes an acquisition portion  14  having a first length L 1  and a first diameter D 1  (i.e., insertion diameter). The acquisition portion defines an acquisition axis AA′. The probe  10  also includes a handle portion  16  having a second length L 2  and a second diameter D 2 . The handle portion defines a handle axis BB′. Generally, the acquisition axis AA′ and the handle axis BB′ are offset such that the axes are nonconcentric. The probe  10  may also have a transition portion  18  between the insertion portion  14  and the handle portion  16 . The combined lengths of components  14 ,  16  and  18  define the overall length of the probe  10 . 
     As discussed above, the dimensions (e.g., lengths and/or diameters) of any or all of these components  14 ,  16  and  18  may vary between probes of different manufactures. Further, these components may be tapered and/or set at an angle to one another. Therefore, to interface different probes  10  to a common positioning device  100  typically requires individual probe interfaces. 
     Accordingly,  FIGS. 4-5  illustrate one embodiment of a probe holder assembly  50  that may be used to interface differently configured ultrasound probes with a positioning device  100  ( FIG. 1B ).  FIG. 4  illustrates the holder assembly  50  alone, while  FIG. 5  shows the ultrasound probe  10  secured within the holder assembly  50 . While the holder assembly  50  is described in conjunction with the positioning device  100  ( FIG. 1B ), it should be appreciated that the holder assembly  50  may be used with any appropriate positioning device. 
     In this embodiment, the holder assembly  50  includes a probe holder  52  and one or more operably connected straps  54  for cinching or securing the handle portion  16  of the ultrasound probe  10  within the probe holder  52 , as shown in  FIG. 5 . The straps  154  may be attached in any appropriate manner, including via threaded or self-tapping fasteners or a snap or press fit. The probe holder  52  forms a recessed surface that, in the present embodiment, is correspondingly shaped to the handle portion  16  of the ultrasound probe  10  such that when the probe  10  is disposed within the probe holder  52  and the holder assembly  50  interfaces with the positioning device  100  ( FIG. 1B ), the acquisition axis AA′ ( FIG. 3 ) defined by the acquisition portion  14  of the probe  10  is concentrically aligned with a fixed rotational axis CC′ of the positioning device  100  ( FIG. 1B ). This allows the acquisition portion  14  of the probe to rotate about a fixed axis CC′, which may provide for improved image registration. 
     In the embodiment of  FIGS. 4 and 5 , differently configured ultrasound probes from different OEMs will utilize different probe holders, with each forming a correspondingly configured recessed surface. That is, the recessed surfaces may be individually tailored for individual probes. While different probes  10  utilize different probe holders  52 , each probe holder  52  utilizes a standardized interface that allows the probe holder  52  and a supported probe  10  to engage with the remainder of the holder assembly  50 . In one embodiment, the selected probe holder  52  is fixably interconnected to a connector  56  through a rod  58 . That is, in this embodiment, the probe holder  52 , the rod  58 , and the connector  56  may be formed of a single, continuous piece. In another embodiment, the selected probe holder  52  is releaseably interconnected to a connector  56  through a rod  58  having a proximal end  60  that is received within a mating aperture (not shown) within the connector  56  and a distal end  62  that is received within a mating aperture (not shown) of the probe holder  52 . It will be appreciated that these apertures may be threaded, utilize a snap-fit configuration or a press fit configuration, or utilize threaded or self-tapping fasteners (e.g., setscrews) to secure the rod  58  therein. It will also be appreciated that any connecting member (e.g., a bar, a plate, etc.) may replace the rod  58 . 
     A mating shaft  102  of the positioning device  100  ( FIG. 1B ) defines the rotational axis CC′ of the positioning device  100 . The connector  56  is adapted to couple with the mating shaft  102  in any appropriate manner that allows the connector  56  to rotate with the mating shaft  102  about the rotational axis CC′ during operation of the positioning device  100 . Accordingly, when the connector  56  is interconnected to the mating shaft  102 , the holder assembly  50 , and thus the supported probe  10 , may be rotated about the rotational axis CC′ of the mating shaft  102 . Notably, when the probe  10  is secured within a selected customized probe holder  52  of the holder assembly  50 , the rotational axis CC′ of the mating shaft  102  is concentrically aligned with the acquisition axis AA′ ( FIG. 3 ) of the probe  10  such that during operation, the positioning device  100  rotates the acquisition portion  14  of the supported probe  10  about the rotational axis CC′ in a manner that is substantially free of precession or wobble. 
       FIGS. 6-7  illustrate another embodiment of a holder assembly  150  for attachment to and use with the positioning device  100 . Like holder assembly  50  discussed above, a connector  156  of the holder assembly  150  may be rotatively coupled with the mating shaft  102  of the positioning device  100  in any appropriate manner that allows the holder assembly  150 , and thus the secured probe  10 , to rotate with the mating shaft  100  substantially without precession. While the probe holder assembly  150  is described in conjunction with the positioning device  100  ( FIG. 1B ), it should be appreciated that the holder assembly  150  may be used with any appropriate positioning device. 
     In this embodiment, the holder assembly  150  incorporates a flexible joint  158 , which allows for more general use of the probe holder  152 . Specifically, the holder assembly  150  includes a probe holder  152  having a recessed surface that can accommodate a variety of different ultrasound probes  10 . One or more straps  154  or clamps are operably connected with the probe holder  152  such that the selected probe  10  may be cinched or otherwise secured within the probe holder  152 , as shown in  FIG. 7 . The straps  154  may be attached in any appropriate manner, including via threaded or self-tapping fasteners or a snap or press fit. 
     Because the probe holder  152  does not have a custom recessed surface for each particular ultrasound probe  10  (i.e., the recessed surface is not configured for each particular ultrasound probe), the holder assembly  150  includes the flexible joint  158  between the probe holder  152  and the connector  156 . The flexible joint  158  allows the recessed surface (which engages the probe handle) of the probe holder  152  to be adjusted to bring the acquisition axis AA′ ( FIG. 3 ) of the secured probe  10  into concentric alignment with the rotational axis CC′ of the positioning device  100  ( FIG. 1B ). As will be discussed below, the flexible joint also includes a locking mechanism to secure the probe holder  152 , and thus the secured probe  10 , in a concentrically aligned position. 
       FIGS. 8-9  illustrate one embodiment of the flexible joint  158  in greater detail. In this embodiment, the flexible joint  158  includes a ball-bar-socket joint (e.g., two ball-and-socket joints joined by a bar) that connects the probe holder  152  with the connector  156 . Specifically, a first ball  160  mates with a corresponding socket (not shown) formed within a proximal end  166  of the probe holder  152 . It should be appreciated that the socket may be formed within a continuous portion of the probe holder  152  or a separate portion (e.g., a plate, a flange, a block, etc.) that is fixably attached to the probe holder  152  via any appropriate method of attachment (e.g., threaded fasteners, adhesive, welding, press fit, snap fit, etc.). 
     A second ball  161  mates with a socket (not shown) formed within an offset portion  168  of the connector  156 . When disposed within the sockets, the first and second balls  160 ,  161  may be adjusted through nearly unlimited degrees of freedom in order to concentrically align the acquisition axis AA′ ( FIG. 3 ) of the supported probe  10  ( FIG. 7 ) with the rotational axis CC′ of the positioning device  100  ( FIG. 1B ). 
     To secure the balls  160 ,  161  in their respective aligned positions within the sockets, two securement plates  164  ( FIG. 9 ) may be disposed about the bar  162  and tightened about each mated ball and socket using threaded fasteners that extend through the securement plates  164  into the material surrounding the sockets on the proximal portion  166  of the probe holder  152  and the offset portion  168  of the connector  156  ( FIG. 8 ), respectively. The balls, sockets, and securement plates may be of any appropriate size, type, and/or configuration such that when tightened, the securement plates  164  compress the balls  160 ,  161  against the walls of the sockets, thereby preventing further rotation of the balls  160 ,  161  within the sockets and locking the probe holder  152  and supported probe  10  in an aligned position. 
     While the flexible joint  158  has been described as having two ball-and-socket joints, it should be understood that the flexible joint  158  may include additional or fewer rotative or other joints of any appropriate size, type, and/or configuration. 
     In some instances, an alignment fixture may be used to adjust the flexible joint  158  as discussed above.  FIG. 10  illustrates the ultrasound probe  10  as secured within the holder assembly  150  and mounted upon one embodiment of an alignment fixture  200 . To allow for adjustment, the flexible joint  158  of the holder assembly  150  remains loosely connected (i.e., the securement plates  164 ,  165  are not fully tightened about the ball-and-socket joints) until the probe  10  has been aligned, as discussed below. 
     The alignment fixture  200  includes a base having a first bar  210  that fixably connects a first end  112  and a second end  214 . The first end  212  includes a mating shaft holder  203  that fixably couples to a second bar  216  through a disk  218 . The mating shaft holder  203  also receives the mating shaft  102  of the positioning device  100  ( FIG. 1B ), which, in turn, is coupled with the connector  156  of the holder assembly  150  in any appropriate manner so as to allow the mating shaft  102  to rotate the connector  156  of the holder assembly  150 , and thus the secured probe  10 . 
     The acquisition portion of the secured probe  10  extends through two apertures  216  formed by corresponding biasing collar assemblies  206  that are coupled to a distal end of the second bar  216 . The biasing collar assemblies  206  allow for the selective and incremental positioning of the acquisition portion  14  of the supported probe  10 . As shown in further detail in  FIG. 11 , each collar assembly  206  includes a collar  208  that is adapted to receive the acquisition portion  14  of the supported probe  10 . An adjustment screw  220  threadably engages with both a top portion  222  and a side portion  224  of the collar  208 . The adjustment screws  220  may be of sufficient length to extend into an aperture  226  formed by the collar  208  such that the adjustment screws  220  contact the acquisition portion  14  of the secured probe  10 . The adjustment screws  220  may be threaded fasteners of any appropriate size, type, and/or configuration that allows the screws  220  to extend through the collar  208  and into the aperture  226 . Thumb knobs  228  may be attached to heads of the adjustment screws  220  to allow an operator to adjust the screws by hand. 
     In addition, biasing members (not shown) are disposed within the aperture  226  and opposite the adjustment screws  222 . The biasing members deflect slightly to accommodate the acquisition portion  14  of the supported probe  210 . This slight deflection causes the biasing members apply a compressive force between the acquisition portion  14  and the adjustment screws  220 . As a result, the biasing members deflect further when the acquisition portion  14  shifts in response to incremental movement of the adjustment screws  218 , thereby allowing the axis AA′ of the acquisition portion  14  of the probe  10  to be concentrically aligned with the rotational axis CC′ of the mating shaft. It should be appreciated that the biasing members may be coil springs, leaf springs, or any other bias springs of appropriate size, type, and/or configuration. 
     To gauge probe alignment, the alignment fixture  200  may also include a dial indicator  230  having a lever arm (not shown) that engages the acquisition portion  14  of the supported probe  10 . As the mating shaft  102  rotates the supported probe  10 , the indicator  230  detects any precession or wobble in the acquisition portion  14  of the probe  10 . If precession is detected, the biasing collar assemblies  206  may be adjusted to bring the acquisition portion  14  of the probe  10  into concentric alignment with the shaft  102 , as discussed above. Once aligned, the securement plates  164 ,  165  of the flexible joint may be tightened about the ball-and-socket joints to secure the probe  10  within the holder assembly  150  in an aligned position. 
     It will be appreciated that though a finite number of exemplary embodiments have been discussed herein, the various elements of those embodiments may be used separately or combined together. For example, the customized probe holder  52  may be used in conjunction with the holder assembly  150  having the flexible joint  158 . 
     The foregoing description of the present invention has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and skill and knowledge of the relevant art, are within the scope of the present invention. The embodiments described above are further intended to explain best modes known of practicing the invention and to enable others skilled in the art to utilize the invention in similar or other embodiments and with various modifications required by the particular application(s) or use(s) of the present invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.