Patent Publication Number: US-2016231452-A1

Title: Tomosynthesis imaging

Description:
BACKGROUND 
     The present application relates to generating via tomosynthesis one or more images respectively depicting a surface of an object under examination, which may be compiled to generate a substantially volumetric image of the object. It finds particular application with radiation systems for industrial and/or security applications where an object can be rotated during an examination to generate images depicting an interior portion of the object and/or to identify items of interest within the object (e.g., defects, threat items, etc.). 
     Today, radiation systems (e.g., radiation imaging systems) such as CT systems, single-photon emission computed tomography (SPECT) systems, digital projection systems, and/or line-scan systems, for example, are useful to provide information, or images, of interior items of an object under examination. The object is exposed to rays of radiation photons (e.g., x-ray photons, gamma ray photons, etc.) from a radiation source and radiation photons traversing the object are detected by a detector array positioned substantially diametrically opposite the radiation source relative to the object. A degree to which the radiation photons are attenuated by the object (e.g., absorbed, scattered, etc.) is measured to determine one or more properties of the object, which in turn may be utilized to identify items of interest. For example, highly dense items of an object typically attenuate more radiation than less dense items, and thus an item having a higher density, such as a bone or metal, for example, may be apparent when surrounded by less dense items, such as muscle or clothing. In a similar way, using such density information, a crack or anomaly in a tire, for example, may be distinguished from other portions of the tire on an image derived from the density information (e.g., on a density image where the intensity of a pixel/voxel corresponds to a density of a portion of the object represented by the pixel/voxel). 
     Images derived from a radiation examination may be two-dimensional or three-dimensional depending upon, among other things, the number of angles at which the object is viewed. By way of example, line-scan systems generally comprise a radiation source configured to emit fan-beam radiation and a single row of detector cells. The radiation source and line of detector cells typically do not move during the examination, and thus respective locations on the object are generally viewed from merely one angle. Accordingly, a two-dimensional projection image of the object is typically acquired. As another example, computed tomography systems generally comprise a radiation source configured to emit cone-beam radiation and a detector array configured to rotate relative to an object under examination. In this way, respective locations on the object are generally viewed from a plurality of angles to facilitate generating a three-dimensional image of the object. 
     SUMMARY 
     Aspects of the present application address the above matters, and others. According to one aspect, a radiation system is provided. The radiation system comprises a radiation source configured to emit radiation into an examination region wherein an object is exposed to the radiation during an examination and a detector array configured to detect radiation that traverses the examination region. The radiation system also comprises an object support configured to rotate the object about an axis of rotation such that first data, indicative a first ray of radiation having a first trajectory and intersecting a first location within the object, and second data, indicative of a second ray of radiation ray having a second trajectory and intersecting the first location within the object, is yielded from the examination. 
     According to another aspect, a method for examining an object via radiation is provided. The method comprises rotating the object, at least partially situated within an examination region, about an axis of rotation while concurrently exposing the object to radiation. The method also comprises detecting radiation that has traversed the object and impinged a detector array to generate data. A first subset of the data is indicative a first ray of radiation having a first trajectory and intersecting a first location within the object and a second subset of the data is indicative of a second ray of radiation having a second trajectory and intersecting the first location within the object. 
     According to another aspect a computer readable medium comprising instructions that when executed perform operations is provided. The operations comprise rotating an object, at least partially situated within an examination region, about an axis of rotation while concurrently translating the object through the examination region and exposing the object to radiation. The operation also comprises detecting radiation that has traversed the object and impinged a detector array to generate data and defining a surface of the object that is of interest. A first location within the object intersects the surface, and the operations further comprise computing a trajectory of a first ray, intersecting the first location and detected during a first period of time, to identify a first subset of the data. The operations also comprise computing a trajectory of a second ray, intersecting the first location and detected during a second period of time, to identify a second subset of the data. The operations also comprise generating an image, focused on the surface, based upon the first subset and the second subset. 
     Those of ordinary skill in the art will appreciate still other aspects of the present application upon reading and understanding the appended description. 
    
    
     
       FIGURES 
       The application is illustrated by way of example and is not limited by the figures of the accompanying drawings, in which like references generally indicate similar elements and in which: 
         FIG. 1  illustrates an example environment of a radiation system. 
         FIG. 2  illustrates a perspective view of an example examination unit. 
         FIG. 3  illustrates a perspective view of an example examination unit. 
         FIG. 4  illustrates a perspective view of an example examination unit. 
         FIG. 5  illustrates a perspective view of an example examination unit. 
         FIG. 6  illustrates a perspective view of an example examination unit. 
         FIG. 7 a    illustrates a cross-sectional view of an example examination unit during a first period of time. 
         FIG. 7 b    illustrates a perspective view of an example object during a first period of time. 
         FIG. 8 a    illustrates a cross-sectional view of an example examination unit during a second period of time. 
         FIG. 8 b    illustrates a perspective view of an example object during a second period of time. 
         FIG. 9 a    illustrates a cross-sectional view of an example examination unit during a third period of time. 
         FIG. 9 b    illustrates a perspective view of an example object during a third period of time. 
         FIG. 10  illustrates a top-down view of an example examination unit. 
         FIG. 11  illustrates a top-down view of an example examination unit. 
         FIG. 12  illustrates a top-down view of an example examination unit. 
         FIG. 13  is a flow diagram illustrating an example method for examining an object via radiation. 
         FIG. 14  is an illustration of an example computer-readable medium comprising processor-executable instructions configured to embody one or more of the provisions set forth herein. 
     
    
    
     DESCRIPTION 
     The claimed subject matter is now described with reference to the drawings, wherein like reference numerals are generally used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide an understanding of the claimed subject matter. It may be evident, however, that the claimed subject matter may be practiced without these specific details. In other instances, structures and devices are illustrated in block diagram form in order to facilitate describing the claimed subject matter. 
     Among other things, a radiation system configured to examine an object (e.g., tire, baggage, patient, etc.) is provided. The radiation system comprises a radiation source and a detector array. In some embodiments, the detector array comprises a limited number of rows of detector cells, such as merely one row. An examination region (e.g., a region in which an object is exposed to radiation) is defined between the radiation source and the detector array. In some embodiments, an object support is configured to translate the object during the examination while rotating the object about an axis of rotation. In some embodiments, the axis of rotation is substantially perpendicular to a plane of a detection surface of the detector array. It may be appreciated that the combination of the translation and the rotation may cause respective locations on the object to be viewed from a plurality of angles to generate volumetric data indicative of the object (e.g., where, for a given location within the object, data corresponding to at least two rays having different trajectories and converging on the given location is available). 
     In some embodiments, the volumetric data may be reconstructed to generate one or more of images respectively focused on a surface of the object. The surface may be planar or non-planar (e.g., curved). By way of example, in some embodiments, a plurality of images are generated respectively depicting a cross-sectional slice (e.g., parallel to a plane of a detection surface of the detector array) of the object. Moreover, in some embodiment, the volumetric data can be reconstructed to generate one or more three-dimensional images of the object (e.g., such as via a tomosynthesis reconstruction technique). 
     Referring to  FIG. 1 , an example arrangement of a radiation system  100  according to some embodiments is provided. It is to be appreciated that the example arrangement is not intended to be interpreted in a limiting manner, such as necessarily specifying the location, inclusion, and/or relative position of the components depicted therein. By way of example, in some embodiments, the data acquisition component  118  is part of the detector array  108 . 
     An examination unit  102  of the radiation system  100  is configured to examine objects  104  (e.g., tires, baggage, patients, etc.) which may be toroid shaped, cube shaped, etc. The examination unit  102  comprises a radiation source  106  (e.g., an ionizing radiation source) and a detector array  108 , which may be encased in a housing  110  to inhibit particulates from collecting on the detector array  108  and/or to shield an environment around the radiation source  106  from exposure to radiation, for example. In some embodiments, the radiation source  106  and/or detector array  108  are fixed in space (e.g., fixed in position relative to the housing  110  and/or an examination region  112 ). 
     An examination region  112 , in which objects  104  are exposed to radiation  114 , is defined between the radiation source  106  and the detector array  108 . Objects  104  are translated through the examination region  112  (e.g., into and out of the page) via an object support  116  such as a conveyor belt or articulating arm. Objects  104  may be translated substantially continuously and/or may be translated intermittently (e.g., such as following a step-and-shoot approach where objects  104  are translated during periods when little to no radiation is being emitted and are not translated while being exposed to radiation). 
     Throughout the figures of the instant application, the direction of translation is labeled as the “z-axis” on the Cartesian coordinate system. The direction of translation is also sometimes referred to herein as the cone-angle direction. Moreover, a detection surface of the detector array  108  generally extends in the cone-angle direction and a fan-angle direction (e.g., which is labeled throughout the figures as the “x-axis” on the Cartesian coordinate system). 
     During the examination of an object  104 , the radiation source  106  emits cone-beam and/or fan-beam radiation  114  from a focal spot of the radiation source  106  (e.g., a region within the radiation source  106  from which radiation  114  emanates) into the examination region  112 . Such radiation  114  may be emitted substantially continuously and/or may be emitted intermittently (e.g., following the step-and-shoot approach where a brief pulse of radiation  114  is emitted followed by a resting period during which the radiation source  106  is not activated). Further, the radiation  114  may be emitted at a single energy spectra or multi-energy spectrums. 
     While the object  104  is being exposed to radiation and/or during resting periods between exposures, the object  104  is further rotated about an axis of rotation via an object rotator of the object support  116 . In some embodiments, the axis of rotation is substantially perpendicular to a plane of the detection surface of the detector array  108  (e.g., the axis of rotation extends substantially parallel to the “y-axis”). In this way, the object  104  is rotated, within the examination region  112 , in a plane substantially parallel to the detection surface of the detector array  108 . In other embodiments, the axis of rotation may intersect the plane of the detection surface at an angle other than 90 degrees. 
     As the emitted radiation  114  traverses the object  104 , the radiation  114  may be attenuated differently by different items of the object  104 . Because different items attenuate different percentages of the radiation  114 , the number of radiation photons detected by respective detector cells of the detector array  108  may vary. For example, more dense items within the object  104 , such as metal strands, may attenuate more of the radiation  114  (e.g., causing fewer radiation photons to impinge a region of the detector array  108  shadowed by the more dense items) than less dense items, such as rubber segments. 
     Radiation detected by the detector array  108  may be indirectly and/or directly converted into signals that can be transmitted from the detector array  108  to a data acquisition component  118  operably coupled to the detector array  108 . The signal(s) may carry information indicative of the radiation detected by the detector array  108  (e.g., such as an amount of charge measured over a sampling period, an energy of respective detected photons, etc.). The data acquisition component  118  is configured to process the signals (e.g., converting the signals from an analog domain to a digital domain, filtering the signals, etc.) and/or to compile signals that were transmitted within a predetermined time interval, or measurement interval, using various techniques (e.g., integration, photon counting, etc.). By way of example, at least some of the signals may be filtered via a ramp-shaped filter kernel to emphasize high frequencies aspects of the signals (e.g., to promote more defined edges in images generated based upon the signals). The compiled signals are typically in projection space and are, at times, referred to as projections. 
     The data and/or projections generated by the data acquisition component  118  may be transmitted to an image generator  120  configured to convert the data from projection space to image space using suitable analytical, iterative, and/or other reconstruction techniques (e.g., tomosynthesis reconstruction, iterative reconstruction, etc.). As an example, an iterative reconstruction technique may be applied wherein a first image is reprojected, enhanced, and/or reconstructed multiple times to reduce a ghosting effect (e.g., due to an incomplete volumetric data set for respective locations within the object caused by respective locations being viewed a limited number of times). 
     In some embodiments, one or more two-dimensional images are generated by the image generator  120  and are respectively focused on a surface of the object (e.g., a two-dimension manifold of the object). For example, a first two-dimensional image may be focused on a first surface and a second two-dimensional image may be focused on a second surface. The first two-dimensional image may be generated based upon data corresponding to rays of radiation that converge at locations on the first surface and the second two-dimensional image may be generated based upon data corresponding to rays of radiation that converge at locations on the second surface. Respective surfaces may be planar or non-planar. Moreover, in some embodiments, the data may be compiled and/or interpolated to generate a volumetric image and/or to acquire volumetric information about the object  104  (e.g., an approximate location, in three-dimensional space, of an item inside the object). 
     The example system or environment  100  also includes a terminal  122 , or workstation (e.g., a computer), configured to receive information about the object  104  such images generated by the image generator  120 , alerts regarding possible identification of an item of interest (e.g., from an item detection component configured to analyze the data yielded from the data acquisition component  118  and/or images generated by the image generator  120 ), etc. The information received by the terminal  122  can be displayed on a monitor  124  to a user  126  (e.g., quality inspector, security personnel, etc.). In this way, the user  126  can identify items of interest and/or verify results of an item detection component, for example. Further, the terminal  122  may be configured to receive user input which can direct operations of the examination unit  102  and/or alter how information is presented to the user  126 . As an example, in some embodiments, the terminal  122  may be configured to receive user input defining and/or selecting a surface of the object  104  that is of interest and/or defining a number of two-dimensional images to generate (e.g., thus defining a desired number of surfaces). By way of example, one or more defects in a tire may be more likely to occur at a known location. Thus, a quality inspector may request that the image generator  120  generate an image focused on a surface that includes the known location to facilitate an examination of the known location for defects. 
     A controller  128  is operably coupled to the terminal  122  and is configured to control operations of the examination unit  102 . By way of example, in some embodiments, the controller  128  may be configured to translate instructions received from the terminal  122  into commands for the examination unit  102 . 
       FIG. 2  illustrates a perspective view of an examination unit  200  (e.g.,  102  in  FIG. 1 ) wherein a housing (e.g.,  110  in  FIG. 1 ) is removed to show an interior portion of the examination unit  200 . The examination unit  200  comprises a radiation source  202  (e.g.,  106  in  FIG. 1 ) and a detector array  204  (e.g.,  108  in  FIG. 1 ). The detector array  204  comprises a plurality of detector cells  206  typically arranged into columns and rows. The number of columns and/or rows may depend upon, among other things, a desired resolution of images yielded from the examination. 
     In the illustrated embodiment, the detector array  204  comprises a single row of detector cells  206  extending in a fan-angle direction (e.g., along the x-axis) and a plurality of columns of detector cells  206  (e.g., where respective columns merely comprise a single detector cell) extending in the cone-angle direction (e.g., along the z-axis). Moreover, due to the detector array  204  comprising a single row of detector cells  206 , the radiation source  202  is configured to emit fan-beam radiation  208  (e.g., which has little to no outwardly expansion in the cone-angle direction). Thus, an examination region  210  (e.g.,  112  in  FIG. 1 ) formed between the radiation source  202  and the detector array  204  substantially corresponds to a vertical plane (e.g., with little to no dimension in the cone-angle direction). For purposes of this example, an examination line  212  has been superimposed to represent a fan-angle component of the examination region  210 . At a given instant in time, aspects of an object  214  (e.g.,  104  in  FIG. 1 ) intersecting the examination line  212  are being examined (e.g., while other aspects of the object  214  not intersecting the examination line  212  are not being examined). 
     The examination unit  200  further comprises an object support (e.g.,  116  in  FIG. 1 ), which in the example embodiment, comprises a conveyor belt  216  and an articulating arm  218 . The conveyor belt  216  is configured to translate the object  214  through at least a portion of the examination unit  200  and/or to position the object  214  proximate the articulating arm  218 . The articulating arm  218  is configured to lift the object  214  from the conveyor belt  216 , translate the object  214  through the examination region  210 , and/or rotate the object  214  about an axis substantially perpendicular to a detection surface of the detector array  204  (e.g., in the x-z plane). Due to the articulating arm  218  being configured to rotate the object  214  about the axis, the articulating arm  218  may sometimes be referred to herein as an object rotator. The speed of rotation and/or speed of translation may be application specific and/or may depend upon a desired sampling density (e.g., where the sampling density is a function of the number of angles from which a location is viewed). By way of example, in some embodiments, the articulating arm  218  is configured to rotate the object  214  a full 360 degrees for every one centimeter translation of the object  214  in the z-direction. 
       FIGS. 3-6  illustrate an example operation of the examination unit  200  (e.g., wherein lines delineating respective detector cells  206  have been removed for ease of understanding). The conveyor belt  216  may be configured to feed the object  214  into the examination unit  200  and to position the object  214  proximate the articulating arm  218 . Sensing the proximity of the object  214  to the articulating arm  218 , the articulating arm  218  may maneuver a grapple portion  220  of the articulating arm  218  towards the object  214  to make contact with the object  214 . Once the grapple portion  220  is connected to the object  214 , the grapple portion  220  of the articulating arm  218  may be raised  222 , as shown in  FIG. 3 , to suspend the object  214  (e.g., such that the object  214  is not in contact with the conveyor belt  216 ). 
     With the object  214  suspended above the conveyor belt  216 , the articulating arm  218  may translate  224  the object  214  in the cone-angle direction toward and/or through the examination region  210  as illustrated in  FIGS. 4-6 . Numerous techniques are contemplated for translating  224  the object  214  toward and/or through the examination region  210 . By way of example, in some embodiments, the articulating arm  218  may be attached to a rail that extends in the cone-angle direction and the articulating arm  218  may be configured to be maneuvered along the rail, causing the articulating arm  218  and object  214  to be translated  224  in the cone-angle direction. In other embodiments, the object  214  may be translated  224  without physically moving the articulating arm  218 . For example, the grapple portion  220  may be configured to pivot on the articulating arm  218  to translate the object toward and/or through the examination region. Moreover, while reference is made herein to an articulating arm  218  configured to translate and/or rotate the object  214 , other suitable devices for performing such translation and/or rotation are also contemplated. 
     In  FIGS. 4-6 , the examination line  212  has been superimposed onto the object  214  to illustrate which portion of the object  214  is presently being examined. While the object  214  (e.g., or rather a portion thereof) is being examined, the articulating arm  218  or a grapple portion  220  thereof is configured to rotate the object  214  about an axis of rotation  226 . In some embodiments, the axis of rotation  226  is substantially perpendicular to a detection surface of the detector array  204 . Moreover, in some embodiments, the object  214  is rotated while continuing to be translated in the z-direction. 
     As shown in  FIG. 4 , during a first period of the examination, a first location  228  on the object (e.g., as represented by the black dot) may not be examined. However, due to object  214  being (e.g., concurrently) translated and rotated during the examination, the first location  228  on the object may be examined during other periods of the examination. For example, during a second period of time as shown in  FIG. 5 , the first location  228  is examined for a first time, and during a third period of time as shown in  FIG. 6 , the first location  228  is examined for a second time. In this way, by rotating the object  214  and translating the object during the examination, respective locations within the object are viewed multiple times during an examination and are viewed from different angles, as will be explained in more detail below. 
       FIGS. 7-9  illustrate how a first set of rays of radiation, respectively having a different trajectory, can intersect the first location  228  (e.g., represented by the black triangle) to facilitate viewing the first location  228  from multiple angles. Data corresponding to this first set of rays can then by processed (e.g., via tomosynthesis techniques) to create a first image depicting a first surface of the object  214  that includes the first location  228 . Further, data corresponding to a second set of rays (e.g., which may include one or more rays of the first set) intersecting a second location  230  (e.g., represented by the black rectangle) can be processed to create a second image depicting a second surface of the object  214  that includes the second location  230 , for example. 
       FIGS. 7   a,    8   a,  and  9   a  represent a cross-sectional view of the examination unit  200  at the examination line  212 , where the object  214  is translated into and/or out of the page.  FIGS. 7   b,    8   b,  and  9   b  respectively represent a perspective view of the object  214  whereon the examination line  212  has been superimposed. Moreover, a dot  232  has been superimposed on a surface of the object  214  to represent an approximate x-coordinate and z-coordinate of the first location  228  and the second location  230  relative to the examination line  212 . 
     Turning to  FIG. 7   a,  a cross-sectional view of the examination unit  200  and the object  214  during a first period of time (e.g., such as shown in  FIG. 5 ) is provided. During the first period of time, the first location  228  and the second location  230  are proximate a front of the examination line  212  on the page (e.g., as evident from  FIG. 7B ). A first ray  234  intersecting the first location  228  and having a first trajectory is drawn on the cross-section view. The first ray passes to the left of the second location  230  (e.g., not intersecting the second location  230 ) and intersects the detector array  204  at a first fan-angle  236 . 
     Turning to  FIG. 8   a,  a cross-sectional view of the examination unit  200  and the object  214  during a second period of time (e.g., such as shown in  FIG. 6 ) is provided. During the second period of time, the first location  228  and the second location  230  are proximate a back of the examination line  212  on the page and the examination line has moved slightly to the right on the page (e.g., as evident from  FIG. 8 b   ) (e.g., relative to where the examination line  212  was located relative to the object  214  during the first period of time). A second ray  238  intersecting the first location  228  and having a second trajectory is drawn on the cross-section view. The second ray  238  passes to the right of the second location  230  (e.g., not intersecting the second location  230 ) and intersects the detector array  204  at a second fan-angle  240 . 
     Turning to  FIG. 9   a,  a cross-sectional view of the examination unit  200  and the object  214  during a third period of time is provided. During the third period of time, the first location  228  and the second location  230  are proximate a center of the examination line  212  on the page and the examination line  212  has moved further to the right on the page (e.g., as evident from  FIG. 9 b   ) (e.g., relative to where the examination line  212  was located relative to the object  214  during the first period of time and/or the second period of time). A third ray  242  intersecting the first location  228  and having a third trajectory is drawn on the cross-section view. The third ray  242  intersects the second location  230  and intersects the detector array  204  at a third fan-angle  244 . 
     By comparing the trajectory of the first ray  234 , the second ray  238 , and the third ray  242 , it may be evident that first ray  234 , second ray  238 , and the third ray  242  converge at the first location  228  (e.g., such that the only location where all three rays intersect is the first location  228 ). Accordingly, using data corresponding to the first ray  234 , the second ray  238 , and the third ray  242  (e.g., respectively having a different fan-angle  236 ,  240 ,  244 ), an approximate attenuation caused by a portion of the object at the first location  228  can be determined and/or an estimated density, z-effective, or other characteristic of the portion of the object at the first location  228  can be determined. Moreover, the data corresponding to the first ray  234 , the second ray  238 , and the third ray  242  can be combined with data corresponding to other rays that converge along other locations intersecting a desired surface of the object  214  to generate an image representing (e.g., focused on) the desired surface. 
     It may be appreciated that due to the nature of rotating an object  214  about an axis of rotation  226 , the sampling density (e.g., which is a function of the number of angles from which a location is viewed) may vary across the object  214  (e.g., causing aspects of the object  214  closer to the axis of rotation  226  to appear brighter) in some embodiments. For example, the sampling density at locations near an axis of rotation  226  may be greater than the sampling density at locations further from the axis of rotation  226 . 
     In some embodiments, such variations in sampling density may be compensated using software approaches and/or hardware approaches. By way of example, in some embodiments, the projection data generated by a data acquisition component (e.g.,  118  in  FIG. 1 ) may be weighted based upon the distance between the portion of the object  214  represented by the projection data and an axis of rotation  226 . For example, projection data corresponding to a portion of the object  214  further away from the axis of rotation  226  may be weighted more than projection data corresponding to a portion of the object  214  closer to the axis of rotation  226 . As another example, in some embodiments, a sample rate of one or more detector cells of the detector array  204  may be adjusted based upon the distance between the portion of the object  214  being examined and the axis of rotation  226 . By way of example, the sampling rate of at least some detector cells may be decreased as the axis of rotation  226  approaches the examination field. By way of example, the sampling rate of detector cells near a central portion of the detector array  204  (e.g., close to the axis of rotation  226 ) may decrease while the sampling rate of detector cells in more distal portions of the detector array  204  may increase or at least not be decreased because those distal cells are farther away from the axis of rotation  226 . 
     Further, it may be appreciated that while reference is made herein to rotating the object  214 , in some embodiments, the detector array  204  may also be rotated such as described in International Publication WO/2012/173597 which is incorporated herein by reference. In some embodiments, the detector array  204  is rotated about a second axis of rotation which may be parallel to the first axis of rotation, for example. Further, in some embodiments, the object support may be configured to rotate the object  214  in a different direction that the detector array  204  is rotated. By way of example, the object support may be configured to rotate the object  214  in a first direction (e.g., clockwise) and the detector array  204  may be rotated in a second direction (e.g., counter-clockwise) that is opposite to the first direction. In this way, a sampling density may be increased (e.g., to increase a number of surfaces that can be represented in images and/or to improve a resolution of the images), for example. 
     Moreover, while  FIGS. 2-9  describe a detector array  204  as having a single row of detector cells extending in the fan-angle direction, the orientation of the detector array  204  may be determined on an application-by-application basis based upon the object(s) to be examined and/or desired image parameters, for example. By way of example,  FIGS. 10 and 11  illustrate top-down views of other example orientations of the detector array  204 . More specifically,  FIG. 10  illustrates an example detector array  204  having a longitudinal dimension (e.g., a longest dimension) extending in the cone-angle direction (e.g., the row of detector cells extends in a direction parallel to the direction of translation  224 ), and  FIG. 11  illustrates an example detector array  204  having a longitudinal dimension extending diagonally across the conveyor belt  216 . 
     Further, it is to be appreciated that in some embodiments, the detector array  204  may comprise multiple rows of detector cells and multiple columns of detector cells and/or the examination unit  102  may comprise multiple detector arrays. By way of example,  FIG. 12  illustrates a top-down view of a portion of an examination unit comprising two detector arrays  1202 ,  1204  (e.g., respectively comprising a single row of detector cells) which respectively have a longitudinal dimension extending in the cone-beam direction. 
     Referring to  FIG. 13 , a flow diagram of an example method  1300  for examining an object via radiation, such as x-ray radiation and/or gamma radiation is provided. The method  1300  starts at  1302 , and an object, at least partially situated within an examination region, is rotated about an axis of rotation during an examination of the object at  1304  while concurrently exposing the object to radiation and/or while concurrently translating the object through the examination region. In some embodiments, the axis of rotation is substantially perpendicular to a detection surface of a detector array of a radiation system configured to examine the object. In other embodiments, the axis of rotation is angled at an angle of other than 90 degrees relative to the detection surface. 
     At  1306  in the example method  1300 , radiation that has traversed the object and impinged the detector array is detected to generate data. 
     At  1308  in the example method  1300 , a surface of the object that is of interest is defined. The surface may be planar or non-planar and intersects a first location within the object. In some embodiments, the surface corresponds to a cross-sectional slice of the object that is substantially parallel to a detection surface of the detector array. In some embodiments, the surface is defined based upon user input. In some embodiments, the surface is defined based upon a desired number of images to be produced and/or a sampling density of the data. 
     At  1310  in the example method  1300 , a trajectory of a first ray, intersecting the first location and detected during a first period of time, is computed to identify a first subset of the data that corresponds to the first ray. At  1312  in the example method  1300 , a trajectory of a second ray intersecting the first location and detected during a second period of time, is computed to identify a second subset of the data that corresponds to the second ray. Typically, the first ray and the second ray follow different trajectories. For example, the first ray may intersect the detector array at a first fan-angle and the second ray may interest the detector array at a second fan-angle. Moreover, while the first ray and the second ray are emitted and detected at different times, the first ray and the second ray may be said to (e.g., spatially) converge at the first location because the first ray and the second ray both intersect the first location while having different trajectories (e.g., and thus diverge at other locations within the object). 
     At  1314  in the example method  1300 , an image is generated that is focused on the surface based upon the first subset of the data and the second subset of the data (e.g., as well as other subsets of the data corresponding to rays of radiation converging at locations along the surface). 
     The example method  1300  ends at  1316 . 
     Still other embodiments involve a computer-readable medium comprising processor-executable instructions configured to implement one or more of the techniques presented herein. An example computer-readable medium that may be devised in these ways is illustrated in  FIG. 14 , wherein the implementation  1400  comprises a computer-readable medium  1402  (e.g., a flash drive, CD-R, DVD-R, application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), a platter of a hard disk drive, etc.), on which is encoded computer-readable data  1404 . This computer-readable data  1404  in turn comprises a set of processor-executable instructions  1406  configured to operate according to one or more of the principles set forth herein. In some embodiments, the processor-executable instructions  1406  may be configured to perform an operation  1408  when executed via a processing unit, such as at least some of the example method  1300  of  FIG. 13 . In other embodiments, the processor-executable instructions  1406  may be configured to implement a system, such as at least some of the example radiation system  100  of  FIG. 1 . Many such computer-readable media may be devised by those of ordinary skill in the art that are configured to operate in accordance with one or more of the techniques presented herein. 
     Although the subject matter has been described in language specific to structural features or methodological acts, it is to be understood that the subject matter of the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as embodiment forms of implementing at least some of the claims. 
     Various operations of embodiments are provided herein. The order in which some or all of the operations are described should not be construed to imply that these operations are necessarily order dependent. Alternative ordering will be appreciated given the benefit of this description. Further, it will be understood that not all operations are necessarily present in each embodiment provided herein. Also, it will be understood that not all operations are necessary in some embodiments. 
     Moreover, “exemplary” is used herein to mean serving as an example, instance, illustration, etc., and not necessarily as advantageous. As used in this application, “or” is intended to mean an inclusive “or” rather than an exclusive “or”. In addition, “a” and “an” as used in this application are generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. Also, at least one of A and B and/or the like generally means A or B or both A and B. Furthermore, to the extent that “includes”, “having”, “has”, “with”, or variants thereof are used, such terms are intended to be inclusive in a manner similar to the term “comprising”. The claimed subject matter may be implemented as a method, apparatus, or article of manufacture (e.g., as software, firmware, hardware, or any combination thereof). 
     As used in this application, the terms “component,” “module,” “system”, “interface”, and the like are generally intended to refer to a computer-related entity, either hardware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a controller and the controller can be a component. One or more components may reside within a process and/or thread of execution and a component may be localized on one computer and/or distributed between two or more computers. 
     Furthermore, the claimed subject matter may be implemented as a method, apparatus, or article of manufacture using standard programming and/or engineering techniques to produce software, firmware, hardware, or any combination thereof to control a computer to implement the disclosed subject matter. The term “article of manufacture” as used herein is intended to encompass a computer program accessible from any computer-readable device, carrier, or media. Of course, those skilled in the art will recognize many modifications may be made to this configuration without departing from the scope or spirit of the claimed subject matter. 
     Further, unless specified otherwise, “first,” “second,” and/or the like are not intended to imply a temporal aspect, a spatial aspect, an ordering, etc. Rather, such terms are merely used as identifiers, names, etc. for features, elements, items, etc. (e.g., “a first channel and a second channel” generally corresponds to “channel A and channel B” or two different (or two identical) channels or the same channel). 
     Although the disclosure has been shown and described with respect to one or more implementations, equivalent alterations and modifications will occur to others skilled in the art based upon a reading and understanding of this specification and the annexed drawings. The disclosure includes all such modifications and alterations and is limited only by the scope of the following claims. In particular regard to the various functions performed by the above described components (e.g., elements, resources, etc.), the terms used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure. In addition, while a particular feature of the disclosure may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application.