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.
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.
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:
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
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.
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
The examination unit 200 further comprises an object support (e.g., 116 in
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
In
As shown in
a,
8
a, and 9a 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.
Turning to
Turning to
Turning to
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
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
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,
Referring to
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
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.
Filing Document | Filing Date | Country | Kind |
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PCT/US2013/064619 | 10/11/2013 | WO | 00 |