Abstract:
Embodiments relate to detector imaging arrays with highly robust mounting of scintillators (e.g., scintillating phosphor screens) to imaging arrays. For example, the detector arrays comprise spacers to define a space between or separate the scintillator from the imaging array. Embodiments according to present teachings can provide projection radiographic imaging apparatuses, including a scintillator, an imaging array including a plurality of pixels formed over a substrate, and a plurality of spacers disposed between an active surface of the imaging array and the scintillator. The spacers can reduce or prevent contact between a surface of the scintillator and the active surface of the imaging array, strengthen or control attachment therebetween, or adjust light transmittance therebetween.

Description:
TECHNICAL FIELD 
     The present application relates to digital radiographic imaging arrays. More specifically, the present application relates to indirect digital radiographic imaging arrays and methods for using the same. 
     DESCRIPTION OF RELATED ART 
     An indirect digital radiographic (DR) detector can include a scintillator (e.g., phosphor scintillating screen) arranged in proximity to an imaging array sensitive to radiation emitted by the scintillator upon absorption of X-rays. In order to maintain high resolution, the scintillating screen can be mounted in contact with the imaging array or within about 1 micron of a surface of the imaging array. Greater spacing between the imaging array and the screen can result in a loss of resolution. For example, this loss of resolution can occur because of multiple reflections of light between the scintillator and the active surface of the imaging array (this phenomena is called light-piping). In addition, greater spacing or non-uniform spacing can result in image non-uniformity because of non-uniformity in optical coupling between the scintillator and the imaging array. 
     Digital radiographic imaging arrays have primarily been used in radiographic settings in which the detector is mounted inside a Potter-Bucky grid (“bucky”) or mounted at a positioning arm. A bucky is a grid used in radiography that reduces or prevents scattered radiation from reaching the film, thereby securing better contrast and definition, and can move during exposure so that no lines appear in the radiograph. In these settings the imaging array is not subject to mechanical vibration or to shock. Recently, however, reductions in the size of digital radiography detectors and introduction of battery-powered imaging arrays with wireless communication have enabled highly portable imaging arrays that can be moved from one location to another. These digital radiography detectors subject the radiographic imaging array to increased shock and/or vibration. In addition, for some imaging procedures, the patient stands or lies on the detector, which can result in localized regions of high pressure. Finally, because of the portability, the opportunity for a detector to be dropped or subjected to shock can be greatly increased. 
     Two primary approaches have been conventionally used to attach a scintillator to an imaging array. In the first, the scintillator can be placed in physical contact with the imaging array using pressure between the non-active surface (substrate) of the imaging array and the substrate of the scintillator. The second approach uses an intermediary layer between the imaging array and the scintillator, for example, a planarization layer, an optical matching layer, an adhesive layer, etc., to attach the scintillator to the imaging array. 
       FIG. 1  illustrates the first of the two conventional techniques to attach a scintillator to an imaging array. In  FIG. 1  an imaging array  175  is shown, including pixels  100 . Each pixel  100  can include switching elements  150  and photosensing elements  140 , as known in the art. Imaging array  175  can be formed on a glass substrate  130 . Also shown in  FIG. 1  is scintillating screen  180  formed on a substrate  120  (referred to herein as scintillator  110 ). Scintillator  110  can be placed over imaging array  175  and pressure can be applied to form an integrated digital detector  190 . However, as can be seen in  FIG. 1 , a gap  160  can form between scintillator  110  and an active surface of imaging array  175 . The active surface of imaging array  175  can display topography between the highest and lowest point of about 1 μm to about 3 μm. In addition, the surface of the scintillator  110  facing the active surface of the imaging array  175  can often display surface roughness on the order of several microns. 
     The arrangement shown in  FIG. 1  can have various disadvantages. For example: 1) non-uniform optical contact between the scintillator  110  and the photosensing elements  140  in the imaging array  175  can result in non-uniformities in sensitivity to X-rays from pixel  100  to pixel  100 ; 2) mechanical grinding between the scintillator  110  and the imaging array  175  can result in damage to the scintillator  110  and/or the imaging array  175  when the scintillator  110  moves with respect to the imaging array  175 ; 3) lateral scattering of light because of reflections off the active surface of the imaging array  175  and the surface of the scintillator  110  facing the active surface of the imaging array  175  can result in loss of resolution; and/or 4) change in position of the scintillator  110  relative to the imaging array  175  due to shock. Since the imaging array  175  and scintillator  110  can be calibrated for pixel-by-pixel gain, a change in position can result in photosensitivity pattern noise because of the calibration no longer being accurate. Also, poor optical coupling of the light from the scintillator  110  to the imaging array  175  can result from optical index matching of the air gap (n=1)  160  formed between the scintillator  110  and the imaging array  175 . 
     Further, changes in the optical coupling of the scintillator  110  to the imaging array  175  can occur when pressure is placed on the substrate  120  of the scintillating screen  110  resulting in localized hot spots. This pressure on the substrate  120  of the scintillator  110  can result from patient positioning. For example, an imaging procedure in which an X-ray of a foot is obtained by the patient standing on the detector array  190  can place localized pressure under the ball and heel of the foot. This exemplary localized pressure can force the scintillator  110  into closer contact with the imaging array  175 , resulting in increased optical coupling. Since the gain calibration is obtained without pressure, localized loss of calibration accuracy can result. 
       FIG. 2  illustrates the second conventional technique to attach a scintillator to an imaging array. In  FIG. 2 , a layer  200  can be added over the active surface of the imaging array  175 . This layer can be a planarization layer as taught, for example, in US20080099687A1 (Konica), U.S. Pat. No. 6,608,312B1 (Canon), and U.S. Pat. No. 6,770,885B2 (GE), all of which are herein incorporated by reference in their entirety. Alternatively, layer  200  can be a liquid index matching material as taught by, e.g., U.S. Pat. No. 6,469,305B2 (Hamamatsu) also herein incorporated by reference in its entirety. Such arranged layers can improve the optical coupling of the light between the scintillator  110  and the imaging array  175  and can reduce the impact of localized pressure on the scintillator  110 , but the arranged layers can also introduce various disadvantages. For example, a planarization layer  200  can increase the distance between the scintillator  110  and the imaging array  175 , which can result in additional lateral optical light piping and consequent loss in resolution. Further, any particulate trapped between the planarization layer  200  and the scintillator  110  can cause scratching and damage to the imaging array  175  upon shock or vibration moving the scintillator  110  with respect to the imaging array  175 . 
     Another conventional technique is taught in JP2002055165A (herein incorporated by reference in its entirety), which teaches using an adhesive material to bond the scintillator  110  to the imaging array  175 . Other conventional detector arrays have utilized spacing beads to maintain a precise separation distance between the scintillator  110  and the imaging array  175  as shown in U.S. Pat. No. 5,506,409A (Hitachi), which is also herein incorporated by reference in its entirety. 
     Conventional methods of mounting the scintillator  110  to the imaging array  175  do not provide sufficiently robust detector arrays  190 . None of the conventional techniques discussed adequately reduce or prevent pressure, shock, and/or vibration from inadvertently moving or shifting the scintillator  110  with reference to the imaging array  175 . Therefore, there is a need to provide a digital radiographic imaging array that is robust to pressure, shock or vibration by improving the attachment of the scintillator  110  with respect to the imaging array  175 . 
     SUMMARY 
     Accordingly, it is an aspect of this application to address in whole or in part, at least the foregoing and other deficiencies in the related art. 
     It is another aspect of this application to provide in whole or in part, at least the advantages described herein. 
     Another aspect of the application is to provide detector imaging arrays with robust mounting of scintillating phosphor screens to imaging arrays. For example, the detector arrays can include spacers to control spacing of the scintillator from the imaging array. For example, the detector arrays can include spacers to attach the scintillator to the imaging array. 
     Exemplary spacers embodiments can be provided at non-active locations on an active surface of the imaging array. The spacers can form a-periodic or periodic patterns on the active surface. The spacers can be positioned at a perimeter of each pixel, including, at the corners of each pixel, along at least a portion or majority of each side of each pixel, or a continuous border around each pixel. Additional layers can be added between the scintillator and the imaging array, including planarization layers, adhesive layers, optical matching layers, protective layers, etc. Embodiments also include exemplary spacer embodiments comprising non-transparent or opaque materials that can be either absorbing or reflective. The spacers can also include colorants. Embodiments of spacers can address light (e.g., transmission, loss, etc.) at borders separating pixels. 
     Another aspect of the application is to provide digital radiography detector imaging arrays and methods that can provide an increase in fill factor for pixels in an imaging array. 
     Another aspect of the application is to provide detector imaging arrays that can provide an alternative routing for metal layers (e.g., bias line), detector imaging array that can increase a fill factor of the pixel and/or maintain low or reduce crossover capacitance between at least two metal layers (e.g., bias line and other clock, data or control lines) in the pixel. 
     Another aspect of the application is to provide digital radiography detector imaging arrays and methods that can enable detection of x-rays impinging on the digital radiography detector. 
     Another aspect of the application is to provide digital radiography detector imaging arrays and methods thereof that can automatically transition the digital radiography detector into and/or out of integration mode (e.g., imaging). 
     Exemplary spacers embodiments can be provided at non-active locations on an active surface of the imaging array. Exemplary spacers can include a component of the imaging array or integrated digital detector over at least one surface of the spacers. 
     Embodiments according to present teachings can provide projection radiographic imaging apparatuses including a scintillator; an imaging array having a plurality of pixels formed over a substrate; and a plurality of spacers disposed between a surface of the imaging array and the scintillator to control spacing between the surface of the imaging layer and the scintillator. The spacers can reduce or prevent contact between a surface of the scintillator and the active surface of the imaging array. 
     Embodiments according to present teachings can provide projection radiographic imaging apparatuses including a scintillator, an imaging array comprising a plurality of pixels formed over a substrate, and spacers disposed between a surface of the imaging array and the scintillator, wherein a component of the imaging array is over at least one of the spacers. 
     Embodiments according to present teachings can provide a method of manufacturing a radiographic imaging apparatus that can include forming an imaging array comprising a plurality of pixels formed on a substrate, forming a plurality of spacers disposed over a first surface of the imaging array, forming a component of the radiographic imaging apparatus over a surface of the spacers, and positioning a scintillator over the components and over the plurality of spacers. 
     Additional embodiments include exemplary methods of manufacturing or modifying detector arrays, including forming an imaging array comprising a plurality of pixels formed on a substrate, and forming a plurality of spacers disposed over an active surface of the imaging array, wherein the height of each spacer is greater than the height of the active surface of the imaging array. The methods further provide for attaching a scintillator to the plurality of spacers to reduce or prevent contact between a surface of the scintillator and the active surface of the imaging array. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various features of the embodiments can be more fully appreciated as the same become better understood with reference to the following detailed description of the embodiments when considered in connection with the accompanying figures, in which: 
         FIG. 1  shows a conventional combination of a scintillator and an imaging array; 
         FIG. 2  shows a different conventional combination of a scintillator and an imaging array; 
         FIG. 3  is a diagram that shows a cross-section of a combined scintillator and imaging array with exemplary spacers, according to present teachings; 
         FIG. 4  is a perspective view from above of an imaging array with exemplary spacers extending along a portion of a perimeter of a plurality of pixels, according to present teachings; 
         FIG. 5  is a perspective view from above of an imaging array with exemplary spacers extending along a perimeter of each pixel, according to present teachings; 
         FIG. 6  is a diagram that shows a related art pixel using a bias line to provide a contact to a top of a photosensor; 
         FIGS. 7A-7C  are diagrams that show a top-down view and cross-sections of an imaging array with another embodiment of spacers, according to present teachings; 
         FIG. 7D  is a diagram that shows a cross-section of a combined scintillator and imaging array with an embodiment of spacers shown in  FIGS. 7A-7C ; 
         FIG. 8  is a diagram that shows a cross-sectional view of a combined scintillator and imaging array with exemplary spacers with metal traces surrounding the spacers to provide a reflective surface extending along a pixel perimeter, according to present teachings; 
         FIG. 9  is a diagram that shows a cross-sectional view of a combined scintillator and imaging array with exemplary spacers with reflective metal traces surrounding the spacers and routing of conductive reflective metal traces to extend toward a contact region, according to present teaching;. 
         FIG. 10  is a diagram that shows a cross-sectional view of a combined scintillator and an imaging array with another embodiment of spacers, according to present teachings; 
         FIG. 11  is a diagram that shows a cross-sectional view of a combined scintillator and an imaging array with exemplary spacers that include a photodiode on a top surface along a perimeter of each pixel, according to present teachings; 
         FIG. 12  is a diagram that shows a cross-sectional view of a cross-sectional view of a combined scintillator and an imaging array with exemplary spacers that include a photosensor on a top surface and areas therebetween include a transparent planarizing material, according to present teachings; 
         FIG. 13  is a block diagram showing an x-ray imaging room having two portable DR receiver panels; 
         FIG. 14  is a diagram that shows a cross-sectional view of a combined scintillator and an imaging array with exemplary spacers and an exemplary conductor coupled to the scintillator, according to present teachings; and 
         FIG. 15  is a diagram that shows a cross-sectional view of another embodiment of exemplary spacers, according to present teachings. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Reference will now be made in detail to the present embodiments (exemplary embodiments) of the invention, examples of which can be illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. In the following description, reference is made to the accompanying drawings that form a part thereof, and in which is shown by way of illustration specific exemplary embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the invention. The following description is, therefore, merely exemplary. 
     For simplicity and illustrative purposes, the principles of the present invention are described by referring mainly to exemplary embodiments thereof. Moreover, in the following detailed description, references are made to the accompanying  FIGS. 3-15 , which illustrate specific embodiments. Electrical, mechanical, logical and structural changes can be made to the embodiments without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense and the scope of the present invention is defined by the appended claims and their equivalents. 
     Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all sub-ranges subsumed therein. For example, a range of “less than 10” can include any and all sub-ranges between (and including) the minimum value of zero and the maximum value of 10, that is, any and all sub-ranges having a minimum value equal to or greater than zero and a maximum value equal to or less than 10, e.g., 1 to 5. Furthermore, to the extent that the terms “including”, “includes”, “having”, “has”, “with”, or variants thereof are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.” As used herein, the term “one or more of ”or “and/or” with respect to a listing of items such as, for example, “A and B” or “A and/or B”, means A alone, B alone, or A and B. The term “at least one of” is used to mean one or more of the listed items can be selected. 
     Further, in the discussion and claims herein, the term “on” used with respect to two materials, one “on” the other, means at least some contact between the materials, while “over” means the materials are in proximity or near each other, but possibly with one or more additional intervening materials such that contact is possible but not required. Neither “on” nor “over” implies any directionality as used herein. The term between as used herein with respect to two elements means that an element C that is “between” elements A and B is spatially located in at least one direction such that A is proximate to C and C is proximate to B or vice versa. The term “conformal” describes a coating material in which angles of the underlying material are preserved by the conformal material. 
     Embodiments according to present teachings include radiographic detector arrays including spacers between the scintillator and the imaging array. The spacers can reduce or prevent movement between the imaging array and the scintillator. Embodiments according to present teachings can also reduce problems with optical contact between the scintillator and the imaging array, with optical coupling between the scintillator and the imaging array, with mechanical grinding between the scintillator and the imaging array, gain calibration, and optical crosstalk between pixels of the detector arrays. 
     Embodiments according to present teachings are shown in  FIGS. 3 through 15 .  FIG. 3  shows an embodiment cross-section of a detector array  190  including spacers  300 .  FIG. 4  shows a perspective (top down) view of an imaging array  175  including spacers  300  forming walls around pixels  100 .  FIG. 5  also is a top down view of an imaging array  175 , but includes spacers  300  forming substantially continuous borders around pixels  100 . 
     In  FIG. 3 , imaging array  175  includes an array of pixels  100 . As shown, pixels  100  include known photosensing elements  140  (e.g., n-i-p photodiodes, p-n junction photodiodes, MIS photosensors, phototransistors, etc.), switching elements  150  (e.g., MOS thin-film-transistors, junction field-effect-transistors, fully-depleted SOI transistors, partially-depleted SOI transistors, Silicon-on-glass transistors, bulk MOS transistors, and bi-polar transistors), read-out circuits (not shown), etc. The photosensing elements  140 , the switching elements  150  and the readout circuits can be substantially co-planar. Also shown are spacers  300  that can be formed over the active surface of the imaging array  175  to provide a selected separation or fixed separation of the imaging array  175  from the scintillator  110 . For example, the spacers  300  that can be formed in a regular pattern or periodic pattern over the active surface of the imaging array  175  to provide a gap between the imaging array  175  and the scintillator  110 . For example, the height of spacers  300  can be higher than the active surface of imaging array  175 . As used herein, the active surface of imaging array  175  is intended to include the surface of the imaging array  175  that faces the scintillator  110  and comprises pixels  100 . Active areas of the active surface of the imaging array  175  can include areas used for photosensing and remaining portions of the active surface can preferable provide potential locations for the spacers  300 . However, in some embodiments, the spacers  300  can be mounted on/over the active areas of the imaging array  175 . 
     Spacers  300  can have various shapes, including, for example, prescribed shapes such as but not limited to rectangular posts, oval posts, circular posts, projections, walls of varying length, width, and thickness, (e.g., see  FIG. 4 ), substantially continuous borders (e.g., see  FIG. 5 ), etc., that can extend a selected amount over the imaging array  175  or descend a selected amount from the scintillator  110  (e.g., separate the imaging array  175  from the scintillator  110 ). In some embodiments, minimum length and width (or height) of the spacers  300  can be limited by processes (e.g., minimum feature size, critical dimensions) used to define the spacers. For photo-lithographically defined spacers, typical flat-panel process capability would require a minimum length and width of approximately 3 microns. Further, a selected or maximum width of the spacers in some exemplary embodiments can be limited by the loss of fill-factor within a detector or imaging array, and the spacers  300  can increase fill-factor losses. For example, when the spacers  300  are placed along the boundary between pixels  100 , the spacers  300  width is less than the boundary width, to avoid fill-factor loss. For an exemplary 150 micron square pixel, an exemplary width of less than 10 microns would be desirable for the spacers  300 . However, the spacers  300  can be formed over the active surface pixel electronics, such as interconnects, readout circuits or bias circuits, which can allow a greater width of the spacers  300 . In length, the spacers  300  can range from the minimum photo-definable size up to a single pixel dimension or several pixels in length or a row-length or column-length of pixels. The selected or minimum thickness (e.g., height) of the spacers  300  should be greater than the calculated or maximum roughness of the scintillator surface opposing the active surface of the imaging array in combination with the thickness required to place the top of the spacer at a greater height than the calculated or measured imaging array topography. 
     For example, if the maximum or measured topography of the imaging array is 1 micron above the location at which the spacer is to be positioned and if the maximum or measured peak-to-valley flatness variation of the scintillator surface is 1 micron, a 2 micron or greater spacer thickness is desired. The selected thickness or maximum thickness of the spacers can be determined by the loss in resolution caused by lateral scattering of light (e.g., light-piping) between the active surface of the imaging array and the opposing surface of the scintillator. Thicknesses for exemplary spacers  300  can be 20 microns or less for 150 micron pixel dimension. In exemplary embodiments, thickness of the spacers  300  can be 15 microns or less, 10 microns or less, 5 microns or less, or 3 microns or less. 
     Further, in one embodiment, spacers  300  can be wider/larger at a lower surface (horizontal cross-section) or bottom surface than at an upper surface or top surface. For example, spacers  300  having tapered sides can improve performance characteristic and/or simplify manufacturing process. Such tapered sides can form linear or non-linear sides. Exemplary tapered spacers  300  are shown in  FIG. 15 . 
     Spacers  300  can reduce or prevent movement in all directions, including vertical, lateral and rotational directions. Spacers  300  can be formed in a periodic array along a surface of the imaging array  175 , for example, between selected pixels  100  or each pixel  100 . For example, the spacers  300  can be formed at one or more corners of a plurality of pixels  100 , along a part of the perimeter of a plurality of pixels  100 , as shown in  FIG. 4 , and/or as a substantially continuous border around each pixel, as shown in  FIG. 5 . As shown, spacers  300  can be placed in non-photosensitive regions  410  of the pixel  100 . In exemplary embodiments, the non-photosensitive regions  410  can include boundaries between pixels, interconnects, readout circuits or bias circuits. For example, exemplary non-photosensitive regions  410  can be from about 3 microns wide to about 14 microns wide. For example, about a 10 micron wide border between pixels  100  that are 150 microns square can be formed. 
     It will be appreciated that spacers  300  can be placed at various locations around a plurality of pixels  100 , selected pixels  100 , each pixel  100 , between some pixels  100 , along edges/perimeters of pixels  100 , at a single pixel  100  in the imaging array  175  and that the examples provided are not intended to be limiting. Also, it will be appreciated that the size (including length, width, and thickness) can also vary according to system requirements and the size and shape of the imaging array. 
     In exemplary embodiments, spacer  300  thickness or width can change or the spacer  300  density can vary throughout the imaging array. For example, the spacer  300  density can be 2×, 5×, 10× in a center region relative to an outer boundary region of the active surface of the imaging array. For example, the spacer  300  thickness can be 1.5×, or 2× in a center region relative to an outer boundary region of the active surface of the imaging array. Further, a transition between the center region and the boundary region can be gradual or tiered. An exemplary gradual transition can be linear or nonlinear increase toward the center region. 
     According to exemplary embodiments, an adhesive layer (not shown) can be added to a surface  310  of the spacers  300  to form a bond to the surface of the scintillator layer  110  facing the spacers  300  to reduce or prevent lateral movement of the scintillator  110  with respect to the imaging array  175 . Alternatively or in addition, a passivation layer (not shown) can be included on the active surface of the imaging array  175 , and the spacers  300  can be formed over or extend through the passivation layer (not shown) to meet the surface of the scintillator  110 . 
     In embodiments, spacers  300  can extend from the active surface of imaging array  175  through gap  160  to the surface of the scintillator  110  facing the active surface of the imaging array  175 . Cavities  320  can be formed between the spacers  300  when one or more spacers  300  form a partial border or continuous border around the perimeters of pixels  100  as shown in  FIG. 4  or  5  (no scintillator shown). When cavities  320  are present (e.g., when spacers  300  include continuous borders around each pixel  100 ), an optical index matching material can be filled in the cavities, e.g., by a fluid wicking method, etc., to improve the poor optical coupling of light from the scintillator  110  to the imaging array  175  resulting from optical index matching of the air gap (n=1)  160  between the scintillator  110  and the active surface of the imaging array  175 . In one embodiment, whenever spacers  300  are used to define a spacing between the imaging array  175  and the scintillator  110 , the optical index matching material can be used to fill the gap  160 . In another embodiment, the optical index matching material can be used to fill the gap  160  above a planarization layer partially covering the spacers  300 . 
     Embodiments of radiographic detector arrays  190  using spacers  300  can reduce problems with non-uniform optical contact between the scintillator  110  and the photosensing elements  140  in the imaging array  175 , which can result in non-uniformities in sensitivity to X-rays from pixel  100  to pixel  100 . Embodiments of radiographic detector arrays  190  using spacers  300  can reduce or remove direct contact between the scintillator  110  and the imaging array  175 . Embodiments of radiographic detector arrays  190  using spacers  300  can reduce localized hot spots. Therefore, the optical coupling between the imaging array  175  and the scintillator  110  can be more consistent or substantially the same for all pixels  100  in the imaging array  175 . Embodiments can also improve problems with mechanical grinding, shock, vibration, differences in coefficients of thermal expansion, etc., between the scintillator  110  and the imaging array  175 , which can result in damage to one or both when the scintillator  110  moves with respect to the imaging array  175 . Embodiments of radiographic detector arrays  190  using spacers  300  can stabilize the scintillator  110  with reference to the imaging array  175 . The stabilization resulting from the use of spacers  300  can also reduce gain calibration errors caused by shock and problems with optical coupling resulting in localized hot spots caused by pressure on the scintillator  110 . By stabilizing the scintillator  110  in relation to the imaging array  175 , pressure, shock, vibration, differences in coefficients of thermal expansion, etc., applied to the radiographic digital detector array  190  can be absorbed or dissipated while reducing or eliminating the scintillator  110  or imaging array  175  movement or relative movement. 
     Additional embodiments can include forming the spacers  300  from opaque materials. Opaque as used herein can include materials that absorb light or reflect light. Absorbing opaque materials can have an exemplary absorption of equal to or greater than about 60%, 80%, or 90% in an exemplary 3-10 micron thickness of spacers  300 . Reflecting opaque materials should have a transmission of less than 40%, 20% or 10% in the 3-10 micron thickness of spacers  300 . Colorants, as used herein can include, dyes, pigments, etc., that can be incorporated into spacers  300  to make the spacers  300  opaque. The spacers  300  can include opaque materials or at least one surface of the spacers  300  can include opaque materials. For example, dye or pigment may be diffused into or transferred onto the surfaces (e.g., side surfaces or a top surface) of the spacers, such as by techniques used to form color filter arrays for displays. 
     Absorbing materials (e.g., colorants, etc.) for the spacers  300  can be used reduce optical crosstalk caused by light piping between the imaging array  175  and the scintillator  110 . For example, if spacers  300  extend along the perimeter of each pixel  100  (as shown in  FIGS. 4 and 5 ), a material forming the spacers  300  can be opaque and/or comprise a colorant that can reduce optical transmission. Spacers  300  can absorb light that otherwise could be detected in adjacent pixels  100 . Alternatively, spacers  300  can reflect light to remain detectable by a corresponding pixel  100 . Reflective spacers  300  can reflect light to reduce crosstalk between pixels  100 . In one embodiment, only one surface (e.g., a top surface) of the spacers  300  can be absorptive or reflective (e.g., both side surfaces). 
     It will be appreciated that incorporation of colorants in photo-patternable materials can block the UV wavelengths used for photolithography and therefore the colorants that are substantially transparent to UV but opaque in the visible spectrum can be used. Use of bleaching dyes which become transparent at high exposures or UV exposure can also be an alternative for photo-patternable materials. Alternatively, an opaque spacer material may be patterned using photoresist and the pattern in the photoresist transferred to the spacer material by subsequent wet etching or dry etching of the underlying spacer material. 
     While reducing or preventing crosstalk, the dyes or colorants also can reduce the signal level because of the optical absorption of the light emitted from the scintillator  110  under the spacers  300 . Some of this light can be reflected back into the scintillator  110  from the metal gatelines and datalines and later detected. Lateral scattering of light caused by reflections off the active surface of the imaging array  175  and the scintillator  110  can result in loss of resolution can be improved by using absorbing spacers  300 . To further improve the overall efficiency of the radiographic digital detector  190 , a wicked-in optical coupling material, as described further below, can also be incorporated. 
     In further embodiments, reflective spacers  300  can be used to address the loss of light in the spacers  300  separating each pixel  100 . The reflecting material can display specular reflection or diffuse reflection. In specular reflection, the angle of incidence equals the angle of reflection, while in diffuse reflection, the resulting reflection can be distributed over a range of angles. High reflectivity can be obtained by using metals such as, aluminum, nickel, chromium, silver, etc. Because the light is not reflected multiple times, wall reflectivity greater than or equal to about 80% can be used. High reflectivity can also be obtained by creating stacks of dielectrics (e.g., interference filters) or using diffuse reflectors, e.g., TiO 2  particles. 
     Embodiments of detector arrays  190  including spacers  300  can be manufactured in many ways, the embodiments discussed below are various example methods, but are not intended to be limiting. For purposes of this disclosure, exemplary method embodiments will include manufacturing spacers  300 . As discussed previously, detector arrays and the methods of manufacturing detector arrays are generally known. 
     Embodiments provide methods of manufacturing spacers  300 . In embodiments, a photo-patternable polymer layer can be coated by spin or spray coating on the imaging array  175  and pre-baked to prepare the layer for photolithography. Examples of photo-patternable polymers include, e.g., photosensitized polyimides, photosensitized BCB, photoresist, etc. Alternatively, a non-photo patternable organic or inorganic material can be deposited or coated on the imaging array  175  followed by a photoresist coating. The photoresist can be patterned and the pattern transferred to the underlying organic or inorganic layer by etching, for example, ion beam milling, reactive ion etching (RIE), etc. The resist can then be removed, leaving spacers  300 . It will be appreciated that photolithography techniques, anisotropic etching techniques, isotropic etching techniques, various deposition techniques, etc. are well known in the art and the techniques can be adjusted as required to obtain desired results herein. 
     In cases in which the coefficient of thermal expansion (CTE) of the scintillator material is different from the CTE of the imaging array, disadvantages described above including damage can be caused as temperature change moves the scintillator  110  relative to the imaging array  175 . When the CTE of the scintillator material is different from the CTE of the imaging array, it is desirable for the spacers  300  to deform laterally to reduce stress between the imaging array  175  and the scintillator  110  caused by differential thermal expansion. In exemplary embodiments, the spacers  300  can be formed using a material with a low Young&#39;s modulus as compared to the scintillator material and/or the imaging array, so that the spacers  300  may deform laterally to reduce stress between the imaging array and the scintillator caused by differential thermal expansion. Examples of spacer materials with low Young&#39;s modulus include RTV. Exemplary spacers  300  can have anisotropic deformation where vertical deformation is less than lateral deformation (e.g., relative to the active surface), lateral deformation is 2×, 5× or 10× the vertical deformation, or vertical deformation is small or minimal. In one embodiment, the vertical deformation is minimal and lateral deformation is designed to counter or sufficient to counter differential CTE effects between scintillator materials and the imaging array. In one embodiment, spacers  300  can comprise partially horizontally (or slanted, vertically) extending materials or inserts (e.g., composite materials) to reduce vertical deformation while maintaining lateral deformation. Embodiments of inserts can extend from a bottom surface of the spacers  300  up to 50%, 75% or 90% of the height of the spacers  300 . An exemplary embodiment of inserts  1510  for spacer  300  is shown in  FIG. 15 . 
     As discussed above, an adhesive material can be applied between the scintillator  110  and the spacers  300  (e.g., to the surface  310 ). The adhesive material can be applied by various methods, including, for example, applying photo-patternable adhesives to the surface of the spacers  300  facing the scintillator  110  and patterning both the adhesive and the spacers  300 , or coating adhesive material on a surface of the scintillator  110  facing the spacers  300  and bonding the scintillator  110  to the spacers  300  by applying, e.g., pressure, heat, chemical processes, combinations thereof, etc. For example, pressure sensitive adhesives can by applied to the surface  310  and attach the spacers  300  to the scintillator  300  by pressure. 
     Alternatively, the spacers  300  can be heated to soften the spacers  300  during bonding to allow attachment to the scintillator  110 . In one embodiment, the scintillator  110  can be heated during attachment to the spacers  300  causing a binder on a top surface to attach the surface  310  of the spacers  300 . In one embodiment, the spacers  300  can have a lower melting temperature than the scintillator  110  or the imaging array  175 , and the spacers  300  can be heated to a softened, tacky state for attachment to the scintillator  110   
     Examples of optically clear adhesives include adhesive 8141 manufactured by 3M™, St. Paul, Minn., which is pressure sensitive adhesive with a thickness of 25.4 um, a refractive index of 1.4742 at 633 nm, a haze level of 0.1%, and a light transmission greater than 99% over the visible spectrum. Gel-Film PF-40/1.5-X0 by Gel-Pak™ Hayward, Calif. is made from cross-linked polymer material. The material adheres to a surface on contact based on surface tension. These adhesives are transparent and come with different sizes and thickness. Typical refractive index is in the range of 1.46 and 1.60. Other pressure sensitive adhesives can be formulated with one or more monomer containing a substituted (or an un-substituted) aromatic moiety to provide a thickness of 12.7 um, a refractive index of 1.48-1.56, a light transmission of greater than 92%, and a good adhesion strength. 
     As discussed above, index matching material can be used in cavities  320  or in the space defined by the spacers  300  between the imaging array  1785  and the scintillator  110  to improve optical coupling between the scintillator  110  and the imaging array  175 . For a scintillator screen having a first index of refraction n 1 , an imaging array having a light accepting surface from a material with index of refraction n 2  and an optical coupling material having an index n 3 , selected or optimal optical coupling occurs when n 3  is equal to the square root of n 1  times n 2 . To provide optical coupling with improved optical efficiency, it is desirable to eliminate or at least significantly decrease the amount of internal reflection that occurs at the interface between scintillator screen  180  and an optical matching material. As long as the index of refraction n 1  is equal to or less than the index of refraction n 3  of the optical matching material, there is little/no loss of light caused by internal reflection; only refraction occurs. As long as the index of refraction n 3  is equal to or less than the index of refraction n 2  of the imaging array, there is no loss of light due to internal reflection; only refraction occurs. 
     For example, consider scintillator screen  180  having an overcoat layer (70 wt. % PMMA+30 wt. % PVDF) with a refractive index of 1.47 at the wavelength of 0.55 um, coupled to imaging array  175  having passivation layer  42  (SiO x N y ) with a refractive index of 1.89 at the wavelength of 0.55 um. The coupling is achieved using an optical matching material layer with a refractive index n 3 . The dependence of optical coupling efficiency on the refractive index of the optical matching material layer for scintillator screens (e.g., Gd 2 O 2 S and CsI screens) can increase from n 3 =n 1  to a peak at n 3  equal to the square root of n 1  times n 2 , then decreases with further n 3  value increase up to n 3 =n 2 . 
     For this example, n 3  equal to the square root of n 1  times n 2  is an index of refraction of 1.67.Below a value n 3  of 1.47 (equal to the value of n 1 ), efficiency drops off steadily. For example, with value n 3  at 1.44, efficiency drops by about 5%. With value n 3  at 1.40, efficiency drops by about 10%. With value n 3  at 1.37, efficiency drops by about 15%. The same general behavior occurs, with incrementally decreasing efficiency, as value n 3  exceeds 1.89, the value of n 2  in this example. The selection of an optical matching material with a refractive index in the range from about 1.44-1.56 at the wavelength of 0.55 um provides optical coupling efficiency within the highest range for this example. 
     In practice, it can be very difficult to obtain the exact same index of refraction from two different materials, even where formulation adjustments are possible. To “substantially match” a refractive index, as the phrase is used in the context of the present disclosure, means that two indices differ from each other by no more than about 0.12, more preferably by no more than about 0.08 and most preferably by no more than about 0.04.With a difference in indices of about 0.12, optical coupling efficiency is reduced by about 15% or less. With a difference of about 0.08, optical coupling efficiency is reduced by about 10% or less. With a difference of about 0.04, optical coupling efficiency is reduced by about 5% or less. 
     Embodiments including an index matching material can include a method of wicking an index matching fluid into gap  160  between the scintillator  110  and the imaging array  175 . As shown in  FIGS. 3-5 , the spacers  300  can control a separation between the imaging array  175  and the scintillator  110  (e.g., cavities  320 ). An edge seal with a small opening (not shown) can be formed (e.g., between the display backplane glass and the counter-electrode glass), air can be evacuated from the gap  160  or the cavities  320 , and, for example, a fluid optical index matching material can be wicked into the small opening, filling the gap  160  or cavities  320  (e.g., between the backplane and the counter-electrode glass). Optionally, the fluid optical index matching material can be gelled or solidified by heat or optical illumination after wicking. 
     To form spacers  300  including colorant, organic or inorganic materials can be used, similar to the above methods. For example, photo-patternable organics can be used by coating a photo-patternable organic material (e.g., photo-sensitized BCB, polyimide, acrylic, etc.) containing colorant on the imaging array  175 . The photo-patternable organic coating can then be exposed to a photomask pattern aligned to the pixels  100  and developed using a developer. Alternatively, a non-photo-patternable organic can be coated on the imaging array  175  with a thin inorganic hard mask (e.g., about 100 nm of silicon dioxide). The inorganic hard mask can be patterned using photolithography and the pattern transferred to the organic non-photo-patternable coating using anisotropic dry etching (e.g., RIE or ion milling). 
     In additional embodiments, inorganic materials (e.g., metal silicides, carbon, etc.) can be vacuum deposited in a layer or a sequence of layers to form spacers  300 . The deposited layers can be patterned by photolithography techniques and then etched using anisotropic dry etch (e.g., RIE or ion milling). Alternatively, a spin-on process can be used. For example, an inorganic precursor (e.g., sol-gel or organo-silicate) can be spun on the imaging array  175 . If the precursor is transparent, a colorant can be added to the spun on coating to make the precursor substantially opaque to light emitted by scintillator  110 . The precursor can then be cured to form a substantially inorganic film, the film can be patterned using photolithography techniques and etched as described above using, e.g., anisotropic dry etch. 
     In other embodiments, dyes can be used as discussed above. Dyes can be diffused into patterned spacers  300  or unpatterned receiving materials. If the spacers  300  are previously patterned, then the spacer  300  material can be, e.g., a photo-patternable layer as discussed above that can also be a dye-receiving material. Following patterning, dye can be diffused (e.g., thermally) into the photo-patternable dye-receiving material. If the spacers  300  include unpatterned receiving materials, a dye-receiving material can be coated on the imaging array  175 . The dye-receiving material can, for example, contain mordants to bind dye molecules. U.S. Pat. No. 4,876,167 teaches uses of mordants to bind dye molecules in organic color filter arrays. Image-wise transfer methods can be used to transfer dye from a dye donor material into the dye-receiving material using, for example, laser dye transfer techniques, or resistive head thermal dye transfer techniques, or patterning a barrier layer coated on the dye-receiving material followed by dye diffusion. 
     Embodiments according to present teachings also include reflective spacers  300 , as discussed above. To manufacture reflective spacers  300  the following methods can be used. A vacuum deposited metal layer can be photolithographically patterned to substantially surround either the organic or inorganic spacers  300  discussed above. Alternatively, plated metal spacers can be formed by patterning a seed layer of metal to substantially surround each pixel  100  and plating the spacers  300  from the seed layer by metal plating. Other embodiments can include forming a diffuse reflecting material through deposition (e.g., spin-coating, vacuum deposition, spray coating, etc.) and patterning (e.g., by shadow-masking or photolithography) to substantially surround each spacer  300 . Additional embodiments can include lamination. For example, a reflective material layer can be transferred by lamination onto the imaging array  175  and patterned (e.g., as part of the lamination process through laser transfer, following lamination using photolithography, or prior to lamination through the use of a donor sheet). 
     As will be obvious to one of ordinary skill in the art, the various embodiments can be combined to form many different combinations, all of which are intended to be incorporated by this disclosure. For example, following fabrication of the reflective spacers  300 , deposition of a thin organic or inorganic encapsulating layer can be performed. This can serve to protect the reflective spacers  300  and prevent oxidation; adhesive attachment to the scintillator  110  can be performed; planarization of the scintillator  110  material prior to attachment to the spacers  300  on the imaging array  175  can be performed, and/or wicking in optical matching material can be performed. 
     One disadvantage of related art backplanes for digital radiography is that the need for a bias line overlying the photosensor can cause a loss in fill factor. Fill factor of a digital X-ray detector can be a percentage of the surface area that is active (e.g., capable of detecting photons). The higher the fill factor the more sensitive the digital X-ray detector.  FIG. 6  is a diagram that shows a related art pixel using a bias line to provide a contact to a top of a photosensor. As shown in  FIG. 6 , a top view and a cross-sectional view of a related art pixel  600  including an exemplary bias line  610 . The bias line  610  can be a conductor fabricated in a metal or the like. For example, the bias line  610  can be fabricated in a metal such as aluminum, which is opaque to light. As shown in  FIG. 6 , the pixel  600  can have a square shape, and the fill factor of a pixel can be approximately 60-66%. As shown in  FIG. 6 , the bias line  610  is approximately 8 microns wide, although; the bias line  610  can be wider or narrower. Further, it is possible to route the bias line  610 , which can be in the fifth layer/level of metal, over the top of the data line, which can be in the second layer of metal, the added capacitive loading on the data line would result in greatly increased noise. The signal-to-noise ratio of the pixel array shown in  FIG. 6  is increased or optimized when the bias line  610  is over a photosensor (e.g., photodiode  620 ) rather than on top of/over a data line or lower metal layer. 
       FIGS. 7A-7C  are diagrams that show an imaging array and cross-sections of an imaging array with another embodiment of spacers, according to present teachings. An imaging array and spacers shown in  FIGS. 7A-7C  can be used for a combined scintillator and imaging array in a projection radiographic imaging apparatus or digital radiography detector as shown in  FIG. 7D . Active areas of the active surface of the imaging array shown in  FIG. 7A  can include areas used for photosensing and remaining portions of the active surface can preferable provide potential locations for the spacers  800 . As shown in  FIGS. 7A-7D , the spacers  800  can be on or over a pixel perimeter (e.g., partially) and can include a conductor (e.g., bias line, trace or metal) routed on a surface (e.g., a top surface) of the spacers  800 . The conductor on/over the spacers  800  in  FIG. 7D  can provide an alternative routing for connections inside the imaging array  775  such as a bias line  810  that can increase a fill factor of the pixel and/or reduce a crossover capacitance between the bias line  810  and other clock lines or signal lines (e.g., data lines) in an imaging array or pixel. Further, the bias line  810  can be formed with improved characteristics (e.g., decreased resistance) by increasing a size or thickness relative to the bias line  610 . 
     As shown in  FIG. 7D , an imaging array  775  can include switching elements  750  and photosensing elements  740  in pixels  700  and scintillator  710  can include scintillating screen  780  formed on a substrate  720 , as known in the art. Imaging array  775  can be formed on a substrate  730  (e.g., glass). Scintillator  710  can be placed over spacers  800  and the imaging array  775  to form an integrated digital detector  790 . Exemplary embodiments of spacers  800  can address various effects of a gap  760  that can form between scintillator  710  and an active surface of imaging array  775 . The active surface of imaging array  775  can display topography between the highest and lowest point of about 1-5 μm. In addition, the surface of the scintillator  710  facing the active surface of the imaging array  775  can often display surface roughness on the order of several microns. An optional planarization layer  705  in  FIG. 7D  can be used with the active surface of the imaging array  775 . 
     In exemplary embodiments, at the spacers  800 , a component of the imaging array  775  or digital detector  790  can be defined that can be coupled to one or more terminals within a pixel  750 . For example, the component of the imaging array  775  or digital detector  790  can be on or over the spacers  800 , formed in or partially inside the spacers  800 , or integrated with or integral to the spacers  800 . 
     In an exemplary embodiment shown in  FIGS. 7A-7D , a conductor on a top surface of the spacers  800  can be a bias line  810  that can be connected to the top terminal of the photosensor (e.g., PIN photodiode  820 ). The bias line  810  on the spacers  800  can be over the data line  830 . As shown in the top view of  FIG. 7A , this exemplary embodiment can increase fill factor for the imaging array  775 . For example, the fill factor in  FIG. 7A  is increased about 3-5% relative to the fill factor of the pixel  600  shown in  FIG. 6 . 
     In exemplary embodiments, the spacers  800  can include spacers  300  as described herein, (e.g., absorptive spacers or reflective spacers described with respect to  FIGS. 3-5 ). 
     Thus, various exemplary methods can be used to manufacture the spacers  800  such as the structure shown in  FIG. 7D . For example, opaque spacers  800  (e.g., spacers  300 ) can be patterned according to one of the methods described above. Further, reflective spacers  800  (e.g., spacers  300 ) can be manufactured according to one of the methods described above. Alternatively, absorptive spacers  800  (e.g., spacers  300 ) can be manufactured with a metal trace patterned thereon according to one of the methods described above. 
     Additional embodiments of the spacers  800  can use both reflective configurations/conductive materials and routing of conductive traces. Exemplary reflective spacers  800  and routing of conductive traces are illustrated in  FIG. 8  and  FIG. 9 . As shown in  FIGS. 8-9 , a reflective material, such as aluminum, can be used to form the conductive trace(s) and the traces extend over the sides of the spacers  800 , making the spacers  800  light reflecting. Further, the reflective conductive material can extend from the spacers  800  into the pixels  700  or the imaging array  775  to connect to components thereof. Exemplary reflective spacers  800  and routing of conductive traces illustrated in  FIG. 9  show a reflective bias line  910  coupled through vias  930  to PIN photodiode  920 . Again, the fill factor in  FIG. 9  is increased relative to the fill factor shown in  FIG. 6 . 
     Additional embodiments of the spacers  800  can use multiple traces in a horizontal (e.g., a first direction) direction, in a vertical (e.g., a second direction) direction or multiple conductors or traces in both horizontal and vertical directions. Some pixel architectures, such as active pixels, require multiple bias and clock lines. For example, a 3T (three transistor) active pixel architecture can use traces for 3 bias voltage lines, 2 clock lines and 1 readout line. Exemplary embodiments of spacers  800  can allow multiple stacked insulated metal traces (e.g., 5) over at least a top surface of the spacers  800 . As illustrated in  FIG. 10 , one embodiment of the spacers  800  can provide a plurality of stacked metal traces  1040  on spacer  800 . The stacked metal traces can be separated by an insulator such as insulating layer  1045 . Similar to embodiments described herein, each of the stacked metal tracers can be electrically connected within the pixels  700  or imaging array  775 . As shown in  FIG. 10 , and optional optically indexed material layer  1025  and an optional protective layer  1015  can be used. 
     In alternative additional embodiments, the component of the imaging array  775  or digital detector  790  on the spacers  800  can include additional elements of pixels, TFTs, or additional components for use by the digital detector. Such examples of the component can be limited only by corresponding size limitations of the spacers  800  dimensions. Such examples of the component at the spacers  800  can include but are not limited to capacitors, diodes, amplifiers, or the like. In one embodiment, optically transparent adhesive materials can be used to couple components at the spacers  800  to the scintillator  710 . 
     In one embodiment, a sheet (e.g., uniform layer, evaporation deposited layer, solution coated layer) of a transparent conductor  1410  (e.g., Indium-tin oxide (ITO), Indium zinc tin oxide (IZTO)) can be put over the scintillator  710 . Then, on each spacer  800 , a contact or bump  1402  can electrically connect the transparent conductor  1410  to the bias line  810  of the array  775  (e.g., photodiode). For example, the layer of transparent conductor  1410  is preferable common to all bias electrodes in the array  775 . A bias voltage source can be connected to the conductor  1410  adjacent to or nearby the imaging array. Accordingly, the resistance of the bias line (e.g., 8 microns wide by 40 inches wide, about 50,000 ohms) can be reduced to about hundreds of ohms, which can be the resistance from the edge to a center portion of to an ITO sheet (e.g., 40 inches by 30 inches). As shown in  FIG. 14 , in one embodiment, a low resistance bias line can be used. Since the bias line can be clocked in array  775  operations, preferably, the bias line can have a fast rise time and fast fall time, and/or a low impedance connection to reduce or limit noise (e.g., high frequency noise coupling). Further, because in the embodiment, shown in  FIG. 14  the transparent conductor is a sheet, a subset of the bumps can be missed without affecting an overall resistance of the bias line. Alternatively, the ITO conductor  1410  can be strips to connect a single or multiple rows/columns of pixels. In one embodiment, multiple strips of the ITO conductor  1410  can be formed to connect within each of a plurality of pixels (e.g., in a row or column) to provide access to different voltage levels or sources (e.g., Vbias, Vsupply, Vground, etc.) using the ITO conductor  1410 . Each strip of the ITO conductor  1410  can have multiple contact points within a pixel. Exemplary strips formed in the ITO conductor  1410  can be formed in parallel or in crossing patterns insulated at potential intersections therebetween. 
     In one embodiment, contract  1402  can act as an adhesive to attach the ITO sheet to the spacers  800  and operate as the electrical contact. For example, pressed gold contacts or indium contacts are an example of a material that can be used for the contact or bump  1402  because such materials are soft enough (e.g., compressible) to provide press contact adhesion between the array  775  and the scintillator  710 . An exemplary transparent conductor  1410  can be 0.1 micron to 1 micron to 5 microns thick. 
     For portable digital radiography, there is often no communication between the X-ray generator and the detector. As a result, the detector (e.g., digital detector  790 ) does not have timing information related to the start of X-ray exposure or the end of X-ray exposure of the X-ray generator. Embodiments of spacers  800  can include a sensor or the like formed at the spacers  800  that can be configured to detect a start of X-ray exposure or an end of X-ray exposure by the X-ray generator. Further, a plurality of photosensors on the spacers  800  can be connected in a prescribed relationship, a column-wise pattern, a row-wise pattern or an area-wise pattern and can be configured to detect the start or the end of X-ray exposure. 
       FIG. 11  is a diagram that shows a cross-sectional view of a combined scintillator and an imaging array with exemplary spacers that include a photosensor on a top surface. As shown in  FIG. 11 , a photosensor on the spacers  800  can be incorporated into the imaging array  775  or the digital detector  790 . In one embodiment, spacers  800  can have a height greater than the topography within the pixel  700  and photodiodes  1120  can be fabricated on the spacers  800  between pixels  700 . Alternatively, the photosensors (e.g., photodiodes  1120 ) can be fabricated on the spacers  300  described herein. 
     An exemplary method for manufacturing the photodiodes  1120  will now be described, although embodiments of the application are not intended to be limited thereby. For example, after fabrication of the thin-film transistor switch (e.g., readout circuit  740 ) in the imaging array  775 , photodiodes can be fabricated both within the pixel (e.g., photosensors  750 ) connected to one terminal of the TFT switch and on top (e.g., photodiodes  1120 ) of the spacers  800  between pixels  700 . In exemplary embodiments, the photodiodes  1120  can be connected in rows, in columns, in paxels or globally in a grid pattern. 
     In operation, current in the grid-shaped photodiodes  1120  on the spacers  800  between pixels  700  can be monitored (e.g., during X-ray exposure). For example, the photodiodes  1120  on the spacers  800  can be connected in turn to amplifiers connected to a processor or controller of the digital detector  790  through read out electronics of the imaging array  775 . Upon the start of X-ray exposure by the X-ray generator, the photocurrent in a large area grid photodiode (e.g., a plurality of electrically connected photodiodes  1120  or row of connected photodiodes  1120 ) can be sensed and the integrated digital detector  790  can be prepared to integrate charge, such as by turning off the TFT switches in the pixels  700 . When the X-ray exposure stops, the photocurrent in the large area grid photodiode (e.g., a plurality of electrically connected photodiodes  1120 ) ceases and the integrated digital detector  790  can be prepared to trigger readout of a the imaging array  775  such as by selective turning on of the TFT switches to correspondingly read out individual pixels  700 . Thus, one or more photosensors on the spacers  800  can be configured to detect the start and the end of X-ray exposure or transition the imaging array  775  between operating modes (e.g., idle mode, exposure mode, readout mode). 
     A number of embodiments to connect subsets of the photodiodes  1120  (e.g., a grid-shaped photodiode) can be used and can be selected according to specific applications of the digital detector  790 . Exemplary embodiments for connecting the photodiodes  1120  can include, but are not limited to photodiodes  1120  such as row-wise connection only or column-wise connection only, so that rows of photosensors or columns of photosensors can be monitored individually. Such configurations can be used with wicked in optical indexed matched materials/fluids. Alternatively, the photosensors can be connected in segmented areas (e.g., paxels) to sense exposure in various regions of the image area. In one embodiment, a subset of connected photosensors on the spacers  800  can be segmented to match selectable exposure regions of the digital detector  790 . 
     Further, various spacers  800  embodiments described herein can be used with the photosensors described herein. For example, the spacers  800  can be fabricated with opaque material to reduce or prevent light scattering from pixel to pixel. Alternatively, the metallilzation used to form either the anode or the cathode contact to the photodiode  1120  may be routed over the edge of the spacers  800  to reflect light, thereby reducing or preventing light scattering from pixel to pixel and increasing sensitivity. Alternatively, sides only of the spacers  800  can be reflective or a single surface (e.g., a top surface) can be absorptive/opaque. Further, exemplary spacers  300  can be used for the spacers  800 . 
     In one embodiment, additional optional layers can be used with the spacers  800 . In exemplary embodiments, the regions between spacers  800  can be filled with an optically transparent material.  FIG. 12  is a diagram that shows a cross-sectional view of a combined scintillator and imaging array where regions between the spacers  800  are filled with an optically transparent planarizing material  1205 , such as BCB or acrylic. Further, an optional protective layer  1215  such as an encapsulating dielectric, such as silicon nitride, can be coated over the planarizing material to improve robustness to scratching. 
     In one embodiment, exemplary scintillator  110  can be coated with additional optional layers (e.g., a protective layer). 
     As will be obvious to one of ordinary skill in the art, the various embodiments can be combined to form many different combinations, all of which are intended to be incorporated by this disclosure. For example, following fabrication of the reflective spacers  800 , deposition of a thin organic or inorganic encapsulating layer can be performed. This can serve to protect the reflective spacers  800  and prevent oxidation. Adhesive attachment to the scintillator  710  can be performed after a planarization layer or optical indexed matching material is deployed. Wicking in a fluid optical matching material can be performed. 
     Referring to  FIG. 13 , there is shown an x-ray imaging room  10  that has an X-ray apparatus  52  that uses two wireless DR receiver panels  12 , one labeled A, the other labeled B. Each DR receiver panel  12  has an integrated controller/CPU as known in the art to control operations thereof. As described herein, digital detectors  190 ,  790  can be used for the DR receiver panel  12 . Each DR receiver panel  12  has a unique identifying serial number or other encoding, typically assigned at time of manufacture. The wireless transmission protocol utilizes this unique encoding as a “signature” for distinguishing between any two or more DR receiver panels  12  from the same manufacturer and for setting up the proper communication channel between the panel and a controller  34 . 
     Still referring to  FIG. 13 , X-ray imaging room  10  has an imaging room  20 , a shielded area in which a patient  14  is imaged and containing an x-ray source  16 , and a control room  30  that includes a display  32  and controller  34  for communicating with DR receiver panels  12  over a wireless interface and containing control logic for executing this function with a selected DR receiver panel  12 . In the embodiment shown in  FIG. 13 , the image is obtained on the active DR receiver panel  12  labeled A; the DR receiver panel labeled B is inactive, not currently being used. An operator interface  36  accepts operator instructions such as to select a DR receiver panel, to communicate with the active DR receiver panel  12  labeled A, and control taking of a selected image of the patient  14 . In the embodiment shown, display  32  is a touchscreen display, enabling the operator or technologist to easily control the X-ray imaging room  10  and select either the A or the B DR receiver panel  12  as the active DR receiver panel for obtaining the image using a graphical user interface (GUI). 
     While the invention has been illustrated with respect to one or more implementations, alterations and/or modifications can be made to the illustrated examples without departing from the spirit and scope of the appended claims. In addition, while a particular feature of the invention can have been disclosed with respect to only one of several implementations, such feature can be combined with one or more other features of the other implementations as can be desired and advantageous for any given or particular function. The term “at least one of” is used to mean one or more of the listed items can be selected. The term “about” indicates that the value listed can be somewhat altered, as long as the alteration does not result in nonconformance of the process or structure to the illustrated embodiment. Finally, “exemplary” indicates the description is used as an example, rather than implying that it is an ideal. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.