Abstract:
The present technique provides a laterally adjustable patient support for a medical imaging system. The laterally adjustable patient support is attachable to a receptor for the medical imaging system via a lateral rail structure, which allows sliding movement along the lateral rail structure in infinitesimal increments. The lateral rail structure also may form a curvilinear path, such as a convex path, which provides additional angular and lateral adjustability of the laterally adjustable patient support. The laterally adjustable patient support also may use a supported weight of the patient to create a positional holding force between the laterally adjustable patient support and the receptor.

Description:
BACKGROUND OF INVENTION  
         [0001]    The present invention relates generally to imaging systems, such as radiographic systems, and more particularly, to digital detectors used in such systems. Even more particularly, the present invention relates to an apparatus and method for supporting a patient&#39;s hands and arms in a non-obstructive location relative to the anatomy of interest.  
           [0002]    Medical diagnostic and imaging systems are ubiquitous in modern health care facilities. Currently, a number of modalities exist for medical diagnostic and imaging systems. These include computed tomography (CT) systems, x-ray systems (including both conventional and digital/digitized imaging systems), magnetic resonance (MR) systems, positron emission tomography (PET) systems, ultrasound systems, nuclear medicine systems, and so forth. Such systems provide invaluable tools for identifying, diagnosing and treating physical conditions and greatly reduce the need for surgical diagnostic intervention. In many instances, these modalities complement one another and offer the physician a range of techniques for imaging particular types of tissue, organs, physiological systems, and so forth.  
           [0003]    Digital imaging systems are becoming increasingly widespread for producing digital data that can be reconstructed into useful radiographic images. In one application of a digital imaging system, radiation from a source is directed toward a subject, typically a patient in a medical diagnostic application, and a portion of the radiation passes through the subject and impacts a detector. The surface of the detector converts the radiation to light photons, which are sensed. The detector is divided into an array of discrete picture elements or pixels, and encodes output signals based upon the quantity or intensity of the radiation impacting each pixel region. Because the radiation intensity is altered as the radiation passes through the subject, the images reconstructed based upon the output signals may provide a projection of tissues and other features similar to those available through conventional photographic film techniques. In use, the signals generated at the pixel locations of the detector are sampled and digitized. The digital values are transmitted to processing circuitry where they are filtered, scaled, and further processed to produce the image data set. The data set may then be used to reconstruct the resulting image, to display the image, such as on a computer monitor, to transfer the image to conventional photographic film, and so forth.  
           [0004]    The foregoing medical diagnostic and imaging systems often require patient support structures to orient the anatomy of interest relative to the imaging detector. In some imaging procedures, such as lateral radiographs of a standing patient, a support structure is necessary to position the patient&#39;s hands and arms so that they do not obstruct the anatomy of interest. The patient&#39;s hands and arms are typically supported either by an apparatus unrelated to the diagnostic imaging equipment, such as an intravenous (IV) pole with sand bags at the base for stability, or by a support attached to the diagnostic imaging equipment. Unfortunately, these support structures provide very little adjustability. Support structures mounted to the diagnostic imaging equipment typically provide adjustability only by pivoting the support or by removing and reattaching the support in one of a number of support positions.  
           [0005]    Accordingly, a need exists for a laterally adjustable patient support that is adjustable at infinitesimal increments across a detector of an imaging system.  
         SUMMARY OF INVENTION  
         [0006]    The present technique provides a laterally adjustable patient support for a medical imaging system. The laterally adjustable patient support is attachable to a receptor for the medical imaging system via a lateral rail structure, which allows sliding movement along the lateral rail structure in infinitesimal increments. The lateral rail structure also may form a curvilinear path, such as a convex path, which provides additional angular and lateral adjustability of the laterally adjustable patient support. The laterally adjustable patient support also may use a supported weight of the patient to create a positional holding force between the laterally adjustable patient support and the receptor.  
           [0007]    In one aspect, the present technique provides a patient support system for a medical imaging system. The patient support system comprises a lateral rail structure attachable to a receptor of the medical imaging system and a patient support movably coupled to the lateral rail structure via a rail guide structure.  
           [0008]    In another aspect, the present technique provides a patient support for an imaging system having a curvilinear rail structure attachable to, and movable with, a radiographic receptor of the imaging system. A limb support is then slidingly coupled to the curvilinear rail structure.  
           [0009]    In another aspect, the present technique provides a medical imaging system having a radiographic receptor. On the radiographic receptor, a patient extremity support is slidingly coupled to a rail structure.  
           [0010]    In another aspect, the present technique provides a method of supporting a patient limb during image acquisition by a medical imaging system. The method comprises the act of sliding a limb support along a rail structure coupled to, and movable with, a radiographic receptor of the medical imaging system. The limb support is then secured in a desired position along the rail structure.  
           [0011]    In another aspect, the present technique provides a method of forming a laterally adjustable limb support for a medical imaging system. The method comprises the act of providing a lateral rail structure attachable to a receptor of the medical imaging system. The limb support is slidingly coupled to the lateral rail structure.  
           [0012]    In another aspect, the present technique provides a patient support structure for a medical imaging system. The patient support structure has patient support means for supporting a patient extremity, while sliding attachment means are provided for coupling the patient support means to a receptor of the medical imaging system. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0013]    The foregoing and other advantages and features of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which:  
         [0014]    [0014]FIG. 1 is a diagrammatical overview of a digital X-ray imaging system in which the present technique may be utilized;  
         [0015]    [0015]FIG. 2 is a diagrammatical representation of the functional circuitry in a detector of the system of FIG. 1 to produce image data for reconstruction;  
         [0016]    [0016]FIG. 3 is a partial sectional view illustrating an exemplary detector structure for producing the image data;  
         [0017]    [0017]FIG. 4 is a circuit schematic illustrating rows and columns of pixels in an exemplary detector;  
         [0018]    [0018]FIG. 5 is a flowchart representing the method of operating an exemplary imaging system for providing image data;  
         [0019]    [0019]FIG. 6 is a perspective view of an adjustable support slidingly coupled to a rail structure disposed on the detector;  
         [0020]    [0020]FIG. 7 is a rear view of the adjustable support illustrating various lateral and angular positions of the adjustable support;  
         [0021]    [0021]FIG. 8 is a rear perspective view of the adjustable support illustrating a friction-based holding mechanism activated by a patient load applied to the adjustable support; and  
         [0022]    [0022]FIG. 9 is a rear perspective view of the adjustable support illustrating a vertical release mechanism. 
     
    
     DETAILED DESCRIPTION  
       [0023]    By way of background, FIG. 1 illustrates diagrammatically an imaging system  10  for acquiring and processing discrete pixel image data. For illustration purposes, system  10  is a digital X-ray system designed both to acquire original image data and to process the image data for display in accordance with the present technique. In the embodiment illustrated in FIG. 1, imaging system  10  includes a source of X-ray radiation  12  positioned adjacent to a collimator  14 . Collimator  14  permits a stream of radiation  16  to pass into a region in which a subject, such as a human patient  18 , is positioned. A portion of the radiation  20  passes through or around the subject and impacts a digital X-ray detector, represented generally at reference numeral  22 . As described more fully below, detector  22  converts the X-ray photons received on its surface to lower energy photons, and subsequently to electric signals, which are acquired and processed to reconstruct an image of the features within the subject. In this exemplary embodiment, the system  10  also includes an adjustable support  202 , which is coupled to the detector  22  slidingly along a rail structure  204 , to provide support for the patient&#39;s hands/arms while acquiring an image of the patient  18 .  
         [0024]    Source  12  is controlled by a power supply/control circuit  24 , which furnishes both power, and control signals for examination sequences. Moreover, detector  22  is coupled to a detector controller  26 , which commands acquisition of the signals generated in the detector  22 . Detector controller  26  may also execute various signal processing and filtration functions, such as for initial adjustment of dynamic ranges, interleaving of digital image data, and so forth. Both power supply/control circuit  24  and detector controller  26  are responsive to signals from a system controller  28 . In general, system controller  28  commands operation of the imaging system to execute examination protocols and to process acquired image data. In the present context, system controller  28  also includes signal processing circuitry, typically based upon a general purpose or application-specific digital computer, associated memory circuitry for storing programs and routines executed by the computer, as well as configuration parameters and image data, interface circuits, and so forth.  
         [0025]    In the embodiment illustrated in FIG. 1, system controller  28  is linked to at least one output device, such as a display or printer as indicated at reference numeral  30 . The output device may include standard or special purpose computer monitors and associated processing circuitry. One or more operator workstations  32  may be further linked in the system for outputting system parameters, requesting examinations, viewing images, and so forth. In general, displays, printers, workstations, and similar devices supplied within the system may be local to the data acquisition components, or may be remote from these components, such as elsewhere within an institution or hospital, or in an entirely different location, linked to the image acquisition system via one or more configurable networks, such as the Internet, virtual private networks, and so forth.  
         [0026]    [0026]FIG. 2 is a diagrammatical representation of functional components of digital detector  22 . FIG. 2 also represents an imaging detector controller or IDC  34 , which will typically be configured within detector controller  26 . IDC  34  includes a CPU or digital signal processor, as well as memory circuits for commanding acquisition of sensed signals from the detector. IDC  34  is coupled via two-way fiberoptic conductors to detector control circuitry  36  within detector  22 . IDC  34  thereby exchanges command signals for image data within the detector during operation.  
         [0027]    Detector control circuitry  36  receives DC power from a power source, represented generally at reference numeral  38 . Detector control circuitry  36  is configured to originate timing and control commands for row and column drivers used to transmit signals during data acquisition phases of operation of the system. Circuitry  36  therefore transmits power and control signals to reference/regulator circuitry  40 , and receives digital image pixel data from circuitry  40 .  
         [0028]    In a present embodiment, detector  22  consists of a scintillator that converts X-ray photons received on the detector surface during examinations to lower energy (light) photons. An array of photodetectors then converts the light photons to electrical signals, which are representative of the number of photons or the intensity of radiation impacting individual pixel regions of the detector surface. Readout electronics convert the resulting analog signals to digital values that can be processed, stored, and displayed, such as in a display  30  or a workstation  32  following reconstruction of the image. In a present form, the array of photodetectors is formed on a single base of amorphous silicon. The array elements are organized in rows and columns, with each element consisting of a photodiode and a thin film transistor. The cathode of each diode is connected to the source of the transistor, and the anodes of all diodes are connected to a negative bias voltage. The gates of the transistors in each row are connected together and the row electrodes are connected to the scanning electronics as described below. The drains of the transistors in a column are connected together and an electrode of each column is connected to readout electronics.  
         [0029]    In the particular embodiment illustrated in FIG. 2, by way of example, a row bus  42  includes a plurality of conductors for enabling readout from various columns of the detector, as well as for disabling rows and applying a charge compensation voltage to selected rows, where desired. A column bus  44  includes additional conductors for commanding readout from the columns while the rows are sequentially enabled. Row bus  42  is coupled to a series of row drivers  46 , each of which commands enabling of a series of rows in the detector. Similarly, readout electronics  48  are coupled to column bus  44  for commanding readout of all columns of the detector. In the present technique, image acquisition rate is increased by employing a partial readout of the detector  22 .  
         [0030]    In the illustrated embodiment, row drivers  46  and readout electronics  48  are coupled to a detector panel  50  which may be subdivided into a plurality of sections  52 . Each section  52  is coupled to one of the row drivers  46 , and includes a number of rows. Similarly, each column driver  48  is coupled to a series of columns. The photodiode and thin film transistor arrangement mentioned above thereby define a series of pixels or discrete picture elements  54  which are arranged in rows  56  and columns  58 . The rows and columns define an image matrix  60 , having a height  62  and a width  64 . Again, as described below, the present technique allows an enhanced number of pixels to be read out via the row and column drivers and readout electronics.  
         [0031]    As also illustrated in FIG. 2, each pixel  54  is generally defined at a row and column crossing, at which a column electrode  68  crosses a row electrode  70 . As mentioned above, a thin film transistor  72  is provided at each crossing location for each pixel, as is a photodiode  74 . As each row is enabled by row drivers  46 , signals from each photodiode  74  may be accessed via readout electronics  48 , and converted to digital signals for subsequent processing and image reconstruction. Thus, an entire row of pixels in the array is controlled simultaneously when the scan line attached to the gates of all the transistors of pixels on that row is activated. Consequently, each of pixels in that particular row is connected to a data line, through a switch, which is used by the readout electronics to restore the charge to the photodiode  74 .  
         [0032]    It should be noted that as the charge is restored to all the pixels in one row simultaneously by each of the associated dedicated readout channels, the readout electronics is converting the measurements from the previous row from an analog voltage to a digital value. Furthermore, the readout electronics are transferring the digital values from  2  rows previous to the acquisition subsystem, which will perform some processing prior to displaying a diagnostic image on a monitor or writing it to film. Thus, the read out electronics are performing three functions simultaneously; measuring or restoring the charge for the pixels in a particular row, converting the data for pixels in the previous row and transferring the converted data for the pixels in a twice-previous row.  
         [0033]    [0033]FIG. 3 generally represents an exemplary physical arrangement of the components illustrated diagrammatically in FIG. 2. As shown in FIG. 3, the detector may include a glass substrate  76  on which the components described below are disposed. Column electrodes  68  and row electrodes  70  are provided on the substrate, and an amorphous silicon flat panel array  78  is defined, including the thin film transistors and photodiodes described above. A scintillator  80  is provided over the amorphous silicon array for receiving radiation during examination sequences as described above. Contact fingers  82  are formed for communicating signals to and from the column and row electrodes, and contact leads  84  are provided for communicating the signals between the contact fingers and external circuitry.  
         [0034]    It should be noted that the particular configuration of the detector panel  22 , and the subdivision of the panel into rows and columns driven by row and column drivers is subject to various alternate configurations. In particular, more or fewer row and column drivers may be used, and detector panels having various matrix dimensions may thereby be defined. The detector panel  22  may be further subdivided into regions of multiple sections, such as along a vertical or horizontal centerline.  
         [0035]    It should be further noted that the readout electronics in the detector generally employ a pipeline type architecture. For example, as the charge is restored to all the pixels in a particular row simultaneously by each of the associated dedicated readout channels, the readout electronics convert the measurements from the previous row from an analog signal to a digital signal. Concurrently, the readout electronics transfer the measured digital values from two rows previous to the data acquisition subsystem. The data acquisition subsystem typically performs some processing prior to displaying a diagnostic image on a display. Thus, the readout electronics in the present technique perform three functions simultaneously.  
         [0036]    [0036]FIG. 4 illustrates an array of pixels  86  located on an exemplary detector having a plurality of column lines and row lines. As illustrated by the array of pixels  86 , each pixel comprises the transistor  72  and the photodiode  74 . It should be noted that the array is made up of a plurality of scan lines  88 ,  90 ,  92  and a plurality of data lines  94 ,  96  and  98 . The scan lines  88 ,  90 ,  92  represent rows of pixels scanned during the imaging process. Similarly, the data lines  94 ,  96  and  98  represent the columns of pixels through which data is transmitted to a data acquisition system. As can be appreciated by those skilled in the art, the scan lines typically recharge the photodiode and measure the amount of charge displaced. The column or data lines typically transmit the data from each row of pixels to the data acquisition system.  
         [0037]    As illustrated, scan line  88 (denoted N in FIG. 4) is coupled to each one of the pixels in that specific row. Additionally, scan line  88  is coupled to each of one of the data lines. For example, scan line  88  is coupled to data line  94  (denoted K in FIG. 4) and data line  98  (K+1). Similarly, each one of the data lines is coupled to each one of the scan lines. Thus, as illustrated for the array of pixels  86 , scan line  88  (N), scan line  90  (N−1), and scan line  92  (N+1) are coupled to data line  94  (K), data line  96  (K−1), and data line  98  (K+1) and so on. It should be understood that each data line is typically coupled to one specific column of pixels and each scan line is coupled to one specific row of pixels. Additionally, although in the present embodiment of FIG. 4, 25 pixels are illustrated, it should be noted that additional pixels may, of course, be incorporated in the pixel array.  
         [0038]    Turning to FIG. 5, a flowchart is represented illustrating a method  100  for operating an imaging system of the type described above. Initially, an X-ray exposure is initiated by an operator, as represented by step  102 . Once an X-ray exposure is taken, the readout electronics within the detector  22  are activated, as indicated by step  104 . As mentioned above, an exposure is taken of a patient, whereby X-rays are transmitted through the patient and received by the detector. The array of pixels  86  typically measures the attenuation of the X-rays received by the detector  22 , via the readout electronics provided within each individual pixel. The readout electronics typically collect data utilizing circuitry associated with each of the pixels, as indicated by step  106 . Once the data are collected for a particular row of pixels, the data are transmitted to a data acquisition subsystem as indicated by step  108 . Once data from one specific row of pixels is transmitted to the data acquisition subsystem, the next row of pixels is scanned and read. Thus, the readout of the next row of pixels is activated, as indicated by step  110 . It should be understood that this process continues until the detector  22 , and more particularly all the pixels, are read out. Subsequently, the collected data are processed and ultimately used to reconstruct an image of the exposure area.  
         [0039]    In operation, the foregoing imaging system  10  may utilize a variety of patient support structures to orient the patient  18  relative to the detector  22 , which may be disposed in a fixed or variable position. For example, the detector  22  may be coupled to a positioning system for moving the detector  22  to a desired orientation relative to the patient  18 , while a laterally adjustable support system  200  provides adjustable patient support relative to the detector  22 . In this exemplary embodiment, the laterally adjustable support system  200  comprises an adjustable support  202  for positioning the patient&#39;s hands and arms so that they do not obstruct the anatomy of interest. The adjustable support  202  is coupled to the detector  22  via the rail structure  204 , which extends laterally across the detector  22 . Accordingly, the patient&#39;s hands may be supported at any lateral position relative to the detector  22  by moving the adjustable support  202  to a desired lateral position along the rail structure  204 .  
         [0040]    The adjustable support  202  comprises an upper hand grip  206 , a lower hand grip  208 , a rail guide structure  210  slidingly coupled to the rail structure  204 , and a vertical extension arm  212  extending from the rail guide structure  210  to the hand grips  206  and  208 . The adjustable support  202  also may comprise an armrest, a vertical adjustment mechanism for the vertical extension arm  212 , and any other desired support and positional adjustment features for the particular application and imaging system. Accordingly, the upper and lower hand grips  206  and  208  and the lateral adjustability of the adjustable support  202  accommodate different arm lengths, heights, and other proportions of patients.  
         [0041]    The sliding mechanism between the rail structure  204  and the rail guide structure  210  may embody any suitable mechanism, such as linear bearings, for providing linear or curvilinear motion. Moreover, the rail structure  204  may form either a straight or a curved path. In this exemplary embodiment, the rail structure  204  has a curved path (e.g., concave or convex) that extends across the detector  22  symmetrically between sides  214  and  216 . FIG. 7 is a rear view of the laterally adjustable support system  200  illustrating the adjustable support  202  in multiple orientations, which facilitate left lateral, center, and right lateral positions of the patient  18  relative to the detector  22 . Accordingly, the lateral adjustability of the adjustable support  202  eliminates the need for multiple supports, or the need for removal and reattachment of the support, to accommodate the various positions of the patient relative to the detector  22 . It also should be noted that the upper-rear mounting of the adjustable support  202  to the detector  22  facilitates tilting of the detector  22  without removal of the adjustable support  202 .  
         [0042]    As illustrated, the curved path of the rail structure  204  provides additional adjustability of the adjustable support  202  relative to the detector  22 . For example, the curved path of the rail structure  204  increases the range of lateral adjustability of the adjustable support  202  by causing the adjustable support  202  to tilt outwardly from a vertical centerline  218  of the detector  22  as the adjustable support  202  is moved outwardly from the vertical centerline  218  toward the sides  214  and  216 . In positions near the sides  214  and  216 , the outwardly angled orientation of the adjustable support  202  accommodates longer arms of larger patients, while also supporting the patient&#39;s wrists with the lower hand grip  208 . The curved path of the rail structure  204  also provides vertical adjustability of the adjustable support  202  relative to the detector  22 . As illustrated, the curved path of the rail structure  204  positions the adjustable support  202  at a relatively higher vertical position near the vertical centerline  218  of the detector  22 . Accordingly, if the patient is facing toward or away from the detector  22  (i.e., center position), then the relatively higher vertical position of the adjustable support  202  accommodates an over-the-head position of the patient&#39;s arms/hands.  
         [0043]    The laterally adjustable support system  200  may utilize any suitable securement mechanism for securing the adjustable support  202  in a desired position along the rail structure  210 . However, in this exemplary embodiment, the laterally adjustable support system  200  has a friction-based securement mechanism. As illustrated by FIG. 8, the geometry of the adjustable support  202  is such that a patient load (e.g., weight of the patient&#39;s hands/arms) applied to one of the hand grips  206  and  208 , as referenced by arrows  220  and  222 , respectively, creates a holding force  224  between the detector  22  and the rail guide structure  210 . For example, the geometry of the adjustable support  202  provides a relatively greater distance  226  between the patient load (e.g., arrows  220  and  222 ) and the rail guide structure  210  than a distance  228  between the holding force  224  and the rail structure  204 . Accordingly, a relatively greater holding force  224  (or pressure) is generated between the detector  22  and the rail guide structure  210  as the patient&#39;s hands/arms are supported by the adjustable support  202 . The holding force  224  (or pressure) may be applied along an edge  230 , as illustrated, or at any other point, edge, or area between the detector  22  and the rail guide structure  210 . In operation, the holding force  224  secures the adjustable support  202  in the desired position on the rail structure  210  by frictionally preventing the rail guide structure  210  from moving along the rail structure  204 . Absent the holding force  224 , the adjustable support  202  is laterally adjustable by applying a lateral force on the support  202  to slide the rail guide structure  210  along the rail structure  204 .  
         [0044]    In certain imaging, configuration, or maintenance procedures, it may be desirable to remove the adjustable support  202  from the detector  22 . For example, if the imaging system  10  is being used for procedures involving the abdomen, then it may be desirable to remove the adjustable support  202 . As illustrated in FIG. 9, the adjustable support  202  is removable from the rail structure  204  by applying a disengagement force  232  to the disengagement mechanism or button  234 . For example, depressing the button  234  may release a hook or a latch structure disposed about the rail structure  204 . However, any suitable catch and release mechanism is within the scope of the present technique.  
         [0045]    While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.