Abstract:
An improved way of using radiographic imagery to capture internal characteristics of a concrete structure, wherein radiographic film is placed on one side of the concrete structure and X-rays are transmitted towards the film from the other side. A target which is selectively radiographically impervious may be interposed to generate location or guidance indicia on the film. The target may itself be non-symmetric, such as being L-shaped, or alternatively or in addition, the location indicia may be non-symmetrically located on the target or alternatively, may be arrayed about the circumference of the target similar to numerals of a clock face. Imagery resulting from radiographic imagery may or may not display inclusions and other anomalies of the concrete structure.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a Continuation-in-Part of U.S. Non-Provisional application Ser. No. 12/136,245 filed Jun. 10, 2008, and claims the benefit of priority thereto. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to viewing into the interior of concrete structures, such as columns, and more particularly, relates to method and apparatus for using radiography to generate images of the interior of concrete structures. 
       BACKGROUND OF THE INVENTION 
       [0003]    It is occasionally necessary to determine internal construction of concrete structures, such as location of inclusions and other anomalies within concrete structures such as concrete columns or slabs, or to confirm the absence of inclusions and anomalies. This situation may arise for example when contemplating core drilling or cutting through the concrete structure. It is highly desirable to avoid impinging upon inclusions, such as reinforcement bars (hereinafter referred to as rebar), conduits, post tensioning cables, and the like. It may also be desirable to discriminate among inclusions, where several inclusions are in relatively close proximity to one another. 
         [0004]    Purposes exist other than avoiding disruption to necessary building elements. For example, it may be desirable to ascertain internal integrity of concrete structures or lack thereof, for example to produce evidence for litigation purposes even if no boring or cutting is to be performed. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention uses radiography both to locate inclusions and other anomalies within concrete and also to confirm absence of inclusions and other anomalies. According to one aspect of the invention, a target for imposing location indicia on the final radiographic image may be employed. For example, the target may comprise a metallic plate having radiopaque letters and numbers formed therein. X-rays passing the target will generate corresponding letters and numbers in the radiographic film which is struck by the X-ray. Of course, the entire target may be radiopaque, with the letters, numbers, or other indicia formed as radiographically permeable material to the same effect. Regardless of its precise nature, and whether it is formed as a positive image or a negative image, the indicia may be employed to determine distances and to enable other indexing or referencing to locate an inclusion identified within the concrete structure being radiographed and to identify locations on concrete not bearing inclusions and other anomalies. 
         [0006]    The target may be specially configured to cooperate with irregularly shaped features of the concrete structure. Illustratively, the target may be L-shaped so that it can be placed snugly against a square or rectangular concrete structure. Alternatively, the target may have location indicia which is asymmetrically or irregularly located on the target. For example, a target placed in the inside corner of concrete walls meeting at a right angle may have indicia specially located so that the internal features of the concrete walls will be appropriately called out, identified, measured, or otherwise made understandable by the corresponding indicia formed on the radiographic film. 
         [0007]    A target may have location indicia in many forms. Traditional targets for target shooting typically have concentric circles or circular zones for providing visual indication of the very center of the target. A radiographic target according to the present invention may have for example a series of unique location indicia such as a progression of alphabetical letters or of numbers arranged in a circle or in plural concentric circles in the manner of numbers representing hours on the face of a clock. These location indicia may be radially arranged from the center of the target, as is typical of clock faces for example. Alternatively, the location indicia may be radially arranged from a central point which is not located in the center of the target. One example is a square target wherein the central point is located at the very corner of the square. This example is appropriate for targets to be placed at the inside corner of concrete structures forming an inside corner, such as two concrete walls coming together to form a right angle. 
         [0008]    According to a further aspect of the invention, the invention may comprise a radiographic image in fixed form such as a radiographic film or paper reproduction generated using the radiographic film, which was made using a target bearing location indicia, which radiographic image in fixed form shows the interior of a concrete structure but which lacks any showing of an inclusion in the concrete. This may be necessary for example to confirm that in a particular portion of a concrete structure, the concrete is solid and uninterrupted by an inclusion, so that that area may be core drilled safely. Alternatively, it may be necessary or desirable merely to confirm that the subject concrete structure is solid and therefore may be regarded as having certain strength properties. 
         [0009]    It is an object of the invention to provide improved elements and arrangements thereof by apparatus for the purposes described which is inexpensive, dependable, and fully effective in accomplishing its intended purposes. 
         [0010]    These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Various objects, features, and attendant advantages of the present invention will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: 
           [0012]      FIG. 1  is a top plan view of a target for imposing indicia onto a radiographic image, according to at least one aspect of the invention. 
           [0013]      FIG. 2  is an environmental top plan view of a target for imposing indicia onto a radiographic image, according to at least one additional aspect of the invention. 
           [0014]      FIG. 3  is an environmental top plan view of a target for imposing indicia onto a radiographic image, according to at least one further aspect of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    The present disclosure is related to U.S. Pat. No., issued on, Ser. No. 12/136,245, filed on Jun. 10, 2008, and hereby incorporates the same in its entirety by reference. 
         [0016]      FIG. 1  shows a target  100  for forming guidance indicia on a radiographic image of an inclusion contained within a substrate, simultaneously with exposing radiographic film to form the radiographic image. For the purposes of this invention, a target such as the target  100  is a device for forming guidance indicia on a radiographic image (an exemplary radiographic image is presented hereinafter) of an inclusion contained within a substrate. The guidance indicia are formed simultaneously with exposing radiographic film to form the radiographic image. Thus internal characteristics of the substrate, such as an inclusion or anomalies, or alternatively, lack of an inclusion and anomalies and the guidance indicia are formed in one film exposure operation on the same image. 
         [0017]    By way of summary, concrete radiography relies on radiated energy such as X-rays to generate images on a film, and may be conducted using a source of radiographic energy, which may be for example any known projector of X-rays, and a radiographic film. The film is placed on one side of a concrete structure and the energy is discharged from the opposite side of the concrete structure against the radiographic film. This will produce images of the interior of the concrete structure such that inclusions and other anomalies in what would otherwise be solid concrete are discernible in the final image. An inclusion may be a structural element, such as rebar, post tensioning cables, and internal conduits, embedded energy cables such as electric wires and optic fibers, anchoring elements such as anchor bolts and threaded sockets embedded within the concrete, and others. Anomalies may include for example voids or zones within concrete wherein the constituency differs from elsewhere within the concrete structure, or is suspected of deviating from desired constituency or characteristics. The singular and plural forms of the terms inclusion and the term anomaly will be understood to be interchangeable as used herein. Constituency may encompass chemical or other contamination, undesired ratios of cement, sand, gravel, or other usual components of concrete, unidentified objects or substances or both, or a zone wherein concrete has or may be thought to be insufficiently cured, insufficiently hydrated, or otherwise may be suspected of deviating from a desired constituency. 
         [0018]    After radiated energy has been discharged through the concrete structure and against the radiographic film, the film may be developed. A first image of the interior of the radiographed concrete structure then results. The developed radiographic film may then be used to generate copies such as paper copies, or may be used to generate digital or other images for storage, transmission to others, enhancement or other digital manipulation, and subsequent reproduction. 
         [0019]    The target  100  may comprise a plate  102  of radiographically pervious material which may be a metal such as aluminum for example bearing radiographically impervious masking material which may be a metal such as lead for example for forming guidance indicia  104 A,  104 B,  104 C,  104 D on the final radiographic image (shown and described hereinafter). Where employed herein, specifically named metals will be understood to be substantially those metals, and may be alloys thereof. Of course, materials other than aluminum may be utilized, such as plastics, ceramics, wood, fiberglass, and others. The plate may be circular as shown, or alternatively may be square, rectangular, or of any other desired outer perimetric shape. The target  100  may have a window  106  which may be employed to enable an observer (not shown) to ascertain the precise location of the target  100  on a substrate being radiographed. The window  106  formed in the plate  102  extends entirely through the plate  102  to enable environmental details to be seen. For example, where the substrate comprises a concrete slab (not shown), the slab may be marked with paint which may be seen through the window  106  when the target  100  is placed on the slab. This enables subsequent replacement of the target  100  in the same place in successive radiographic imaging operations by using the paint to spot the location of the target  100 . 
         [0020]    The radiographically impervious masking material is arranged such that at least some of the guidance indicia is arrayed about the perimeter of the target as a series of spaced apart graphic entities. For example, in  FIG. 1 , indicia  104 A may comprise an arrow which could be used to assure similar orientations of the target in successive radiographic imaging operations. Additional indicia  104 B,  104 C, and  104 D may comprise numerical characters (as shown), or alternatively could comprise alphabetical characters, known symbols such as starts and circles, or any other graphic symbol or character. As shown, the indicial  104 B . . .  104 D are numeric characters arrayed in numerical order. Additional indicia complete a numeric progression. It will be seen that the numeric indicia are arrayed about the perimeter of the plate  102  and are spaced apart at regular intervals. 
         [0021]    Additional indicia in the form of concentric rings  108 ,  110 , and  112  may be provided, and may be centered about the window  106 . 
         [0022]    Where it is desired that indicia such as the indicia  104 A,  104 B,  104 C,  104 D,  108 ,  110 ,  112  be discernible in developed radiogrpahic film, then such indicia may comprise radiographically impervious masking material which may fill grooves formed in the plate  102  or passages passing entirely through the plate  102 . 
         [0023]    The window  106  may have at least one radiographically impervious perimetric visual boundary element  114  which concentrically surrounds the window  106  so as to cause corresponding perimetric indicia surrounding the window  106  to appear on the final radiological image. The visual boundary element  114  may be a groove filled with lead for example. Indicia such as the indicia  104 A,  104 B,  104 C,  104 D,  108 ,  110 , and  112  may be generally arrayed in radial symmetry from the center point  116 . Of course, because there is no constituent material present at the center point  116  due to the window  106 , the center point  116  will be understood to be hypothetical. 
         [0024]    As seen in  FIG. 2 , a target  200  which may in other ways be the structural and functional similar to the target  100  may have indicia  204 B,  204 C, and others in the form of alphabetical characters. The target  200  may have indicia comprising an arrow  204 A and a window  206 . Numerals and alphabetical characters may both appear on a target (not shown) according to other aspects of the invention. 
         [0025]    In the targets  100  and  200 , guidance indicia such as the guidance indicia  104 B,  104 C,  204 B,  204 C are disposed in radial symmetry about the center of the target (such as the point  116  in  FIG. 1 ). 
         [0026]    The targets  100  and  200  are suitable for laying on or against unobstructed concrete surfaces. It may be desirable that a target be placed where an immovable obstruction exists. Turning now to  FIG. 3 , a target  300  may be placed on a concrete slab  2  which is the subject of radiographic imagery in abutment with a concrete column  4  which may project from the slab  2 . The target  300  may have constituency similar to that of the target  100 . The target  300  may have a recess  302  which cooperates with the column  4 . In this example, the center of the target  300  may comprise a partially circular portion  304  which is cut out from the constituent material of the target  300  so that a window will remain after the target  300  has been placed in abutment against the column  4 . 
         [0027]    Unlike the target  100 , wherein indicia is generally arrayed in radial symmetry from the center point  116 , indicia of the target  300  may be disposed asymmetrically about a hypothetical center point of the target (the hypothetic center point is not shown). It will be appreciated that due to a quadrant of the otherwise circular target  300  being omitted from the target  300  to achieve the configuration which enables the target  300  to be placed snugly against the column  4 , the center point of the concentric arcs which form guidance indicia members  304 ,  306 ,  308  is not the same as the actual center point of the target  300 . Therefore, the indicia, including the guidance indicia members  304 ,  306 ,  308  as well as numeric guidance indicia members  310 ,  312 , and  314 , are asymmetrically disposed about the hypothetical actual geometric center point of the target  300 . 
         [0028]    This relationship may be better appreciated in  FIG. 4 , wherein a target  400  having an overall L-shaped exterior perimetric configuration is placed against the column  4  in the same position as the target  300  is seen in  FIG. 3 . The target  400 , apart from its L-shaped outer configuration and layout of guidance indicia  402 ,  404 ,  406 ,  408 ,  410 , and  412 , may be structurally and functionally similar to the target  100  for example. The guidance indicia  402 ,  404 , and  406  may take the form of arcs radiating from a hypothetic geometric point which lies outside the outer boundaries of the target  400 . The guidance indicia  408 ,  410 , and  412  may comprise numeric characters as shown, or may be alphabetical or still other characters. 
         [0029]    The targets  300  and  400 , which are intended to partially surround the exterior of corners formed on a concrete structure must have perimeters bearing an incuse portion such as the recess  302  in  FIG. 3  and a corresponding recess  414  in  FIG. 4  to receive the exterior of the concrete structure. The respective recesses  302  and  414  comprise a right angle projecting into the respective targets  300 ,  400 . Of course, a recess such as the recesses  302  and  414  could be of different angles, or could have configurations other than those comprising two straight edges. 
         [0030]      FIG. 6  shows an image display  600  displaying an image of internal characteristics of a concrete structure, such as a concrete slab (not shown). The image display may take the form of a stratum bearing a radiographic image of the interior of the concrete slab. The image display may be a developed radiographic film, a print made therefrom, a slide made therefrom, or other substrate bearing the radiographic image which has been formed by radiographic imagery of concrete. The radiographic image formed on the image display  600  includes a plurality of indexing marks such as numeric characters  602 ,  604 ,  606 ,  608 ,  610  and others (not called out by reference numerals). Additional location or guidance indicia such as concentric circles  612 ,  614 ,  616  are included in the image. Of course, the indexing marks could be alphabetical characters had the radiographic image used the target  200  for example. These indexing marks are arrayed spaced apart at regular spacing intervals. The indexing marks are derived from use of both a relatively X-ray permeable medium and a relatively X-ray impermeable masking medium, such that different degrees of permeability to X-rays generates on the image display discernible indicia corresponding to the indexing marks. For example, the target  100  may be utilized to generate an image such as that appearing on the image display  600 , so that the lead filled concentric rings  108 ,  110 ,  112  and indicia characters  104 A,  104 B,  104 C,  104 D and others corresponding to lead filled indicia characters are formed on radiographic film due to selective obstruction of X-rays. 
         [0031]    The radiographic image of the concrete structure and the indexing marks  602 ,  604 ,  606 ,  608 ,  610  may be formed in one film exposure operation on the same image by placement of a target such as the target  100  against the concrete structure being radiographed. The internal characteristics of the concrete, such as inclusions (none appear in the image of  FIG. 6 ) and the indexing marks  602 ,  604 ,  606 ,  608 ,  610  are simultaneously produced on the radiographic film. 
         [0032]    It will be seen that while the guidance indicia such as the indexing marks  602 ,  604 ,  606 ,  608 ,  610  are captured in the image of the image display  600 , there are no showings corresponding to inclusions. This confirms that in that portion of the concrete structure which was radiographed to produce the image display  600 , no inclusions are present. This information may be used for example to establish integrity of the radiographed concrete structure, or to confirm that a hole may be safely drilled through that portion of the radiographed concrete structure.