Abstract:
A method includes the steps of producing a first digital x-ray image of a part utilizing a full energy spectrum, producing a second digital x-ray image of the part with a hardened beam correlating to a higher energy portion of the full energy spectrum, subtracting the second x-ray image from the first x-ray image, and using a remainder of the subtracting step to locate the matter.

Description:
BACKGROUND 
       [0001]    Detection of materials that are present within another material using x-rays is particularly difficult if the surrounding material has a significantly higher x-ray absorption characteristic. For such cases, higher x-ray energies are required to penetrate and evaluate the surrounding material which can make the materials with low absorption characteristics essentially invisible in the resulting x-ray image. 
         [0002]    An example of such a case is the detection of casting core material within the metal structure of aerospace components. While the core material is intended to be completely removed before part usage, a costly neutron radiographic procedure is typically invoked to detect residual core material that would be detrimental to the part if left in the part. 
         [0003]    There is a need to be able to detect the presence of material with low x-ray absorption characteristics in the presence of material with high x-ray absorption characteristic in a timely and cost effective manner. In particular, using the method for detection of low x-ray absorption material in conjunction with x-ray inspections already used for inspection of other characteristics of the component such as the presence of voids would provide an especially efficient inspection process. 
       SUMMARY 
       [0004]    An exemplary method disclosed herein includes the steps of producing a first digital x-ray image of a part utilizing a full x-ray spectrum, producing a second digital x-ray image of the part utilizing a higher energy portion of the full spectrum, subtracting the second x-ray image from the first x-ray image, and using a remainder of the subtracting step to locate certain matter. 
         [0005]    In another embodiment of the exemplary method of any of the preceding paragraphs, the method includes creating a first digital x-ray image of the part. 
         [0006]    In another embodiment of the exemplary method of any of the preceding paragraphs, the method includes creating a second digital x-ray image of the part. 
         [0007]    In another embodiment of the exemplary method of any of the preceding paragraphs, the method includes creating a third digital x-ray image of the part. 
         [0008]    In another embodiment of the exemplary method of any of the preceding paragraphs, the method includes enhancing the remainder for detection by a user or through automated algorithms, of the matter. 
         [0009]    In another embodiment of the exemplary method of any of the preceding paragraphs, the method includes creating an image of the remainder in which the matter is displayed. 
         [0010]    In another embodiment of the exemplary method of any of the preceding paragraphs, the method includes a limitation wherein the part is in a same position during the x-raying steps. 
         [0011]    A further exemplary method disclosed herein includes the steps of producing a first digital x-ray image of a blade utilizing a full x-ray spectrum, producing a second digital x-ray image of the blade with a hardened beam correlating to an upper portion of the full spectrum, subtracting the second x-ray image from the first x-ray image, and using a remainder of the subtracting step to locate matter. 
         [0012]    In another embodiment of the exemplary method of any of the preceding paragraphs, the method includes the limitation the full spectrum is between 60-650 Kv. 
         [0013]    In another embodiment of the exemplary method of any of the preceding paragraphs, the method includes the limitation wherein the hardened beam is between 300-650 Kv. 
         [0014]    In another embodiment of the exemplary method of any of the preceding paragraphs, the producing a first x-ray step includes creating a first image of the x-rayed part, the producing a second x-ray step includes creating a second image of the x-rayed part and the subtraction step includes creating a third image of the x-rayed part. 
         [0015]    In another embodiment of the exemplary method of any of the preceding paragraphs, the method includes enhancing the remainder for detection by a user or through automated algorithms, of the matter. 
         [0016]    In another embodiment of the exemplary method of any of the preceding paragraphs, the method includes creating an image of the remainder in which the matter is displayed. 
         [0017]    In another embodiment of the exemplary method of any of the preceding paragraphs, the method includes a limitation wherein the part is in a same position during the x-raying steps. 
         [0018]    A still further exemplary method disclosed herein includes the steps of producing a first digital x-ray image of a blade across a full spectrum, producing a second x-ray of the blade with a hardened beam correlating to an upper portion of the full spectrum, subtracting the second x-ray from the first digital x-ray image, and using a remainder of the subtracting step to locate matter. 
         [0019]    In another embodiment of the exemplary method of any of the preceding paragraphs, the method includes a limitation wherein the full spectrum is between 60-650 Kv and a hardened beam is between 300-650 Kv. 
         [0020]    In another embodiment of the exemplary method of any of the preceding paragraphs, the method includes enhancing the remainder for detection by a user or through automated algorithms, of the matter. 
         [0021]    In another embodiment of the exemplary method of any of the preceding paragraphs, the method includes a limitation wherein the producing a first x-ray step includes creating a first digital image of the x-rayed part, the producing a second x-ray step includes creating a second digital image of the x-rayed part and the subtraction step includes creating a third digital image of the x-rayed part. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The various features and advantages of the present disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows. 
           [0023]      FIG. 1  shows an apparatus for x-raying a part. 
           [0024]      FIG. 2A  shows a first x-ray image of a blade with a first x-ray spectrum using the apparatus of  FIG. 1 . 
           [0025]      FIG. 2B  shows a second x-ray image of a blade with a second, overlapping second x-ray spectrum using the apparatus of  FIG. 1 . 
           [0026]      FIG. 2C  shows a view of the part wherein the second x-ray image is subtracted from the first x-ray image using the apparatus of  FIG. 1 . 
           [0027]      FIG. 3  shows a method of detecting matter in a part using the apparatus of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0028]    Referring now to  FIG. 1 , an x-ray system  5 , includes an x-ray source  10 , as is known in the art, a part (such as a blade  15 ) to be x-rayed and a digital x-ray detector  20 . The x-ray detector  20  is connected to a general purpose computer  25  which receives information from the digital x-ray detector  20 . The x-ray source is driven by a controller  29 . 
         [0029]    Referring now to  FIGS. 2A ,  2 B,  2 C, the blade  15  may be used in the turbine environment in a gas turbine engine (not shown). The blade  15  has an airfoil  40 , a base  45 , a platform  50  and an air passage  55 . Referring to  FIG. 2A , a first image  60  of an x-ray of the blade  15  is displayed including its airfoil  40 , base  45 , platform  50  and the air passage  55 . The blade  15  may be made as noted above of titanium or nickel alloys or the like. For an exemplar, the blade  15  shown herein is made of a nickel alloy. 
         [0030]      FIG. 2A  shows a first image  60  created in a first plurality of pixels (not shown) in which the x-ray source  10  bombards the blade  15  with a full spectrum of energy between 60 and 650 kilovolts (“Kv”) as shown in graph  37 . The data that is recorded at the detector reflects the absorption characteristics of the unwanted material as well as the parent material of the blade  15 . The resultant image, however, is overwhelmed by the highly attenuative parent material. For instance, one can see the main elements of the blade  15  including the airfoil  40 , the base  45 , the platform  50  and the air passage  55 . The first image  60  forms a first part  100  (see  FIG. 3 ) of the process. One of ordinary skill in the art will recognize that other full spectrum energy levels may be required for different materials, or for thicker or thinner portions of other parts  15 . 
         [0031]    In image  60  of  FIG. 2A , one cannot see any foreign material or defects  65  (see residual ceramic core particles  70  in  FIG. 2C ) very well. Such material or defect  65  may also be disposed in the blade  15  and may include dross or other low density particles, porosity, micro-shrinkage, grain boundary separation, or the like. 
         [0032]    As a second part  110  (see  FIG. 3 ) of the process and as shown in  FIG. 2B , a hardened beam (e.g., a spectrum between 300 to 650 Kv or a higher range of the full spectrum of energy—see graph  71 ) is used to bombard the part  15  to create second image  75 , typically with the same plurality of pixels (not shown). By using such higher energy, a second image  75  is shown of the structure of the blade  15 , including the airfoil  40 , the base  45 , the platform  50  and the air passage  55 . One of ordinary skill in the art will recognize that other hardened beams having different ranges of energy may be required to be used for different materials, or for thicker or thinner portions of other parts  15 . One should also note that the first image  60  and the second image  75  is taken while the part  15  is in the same position. There are no registration issues of the two images  60 ,  75  thereby. 
         [0033]    To reveal the material  65 , and as a third part  120  (see  FIG. 3 ) of the process, a third image  80  (see  FIG. 2C ) is created to allow the material  65  to be seen. The second image  75  is subtracted from the first image  60  on a pixel-by-pixel basis within the general purpose computer  25 . The pixels that display in  FIG. 2C  are essentially the remainder of the subtraction step  120 . As shown in graph  91  of  FIG. 2C , the spectrum shown relates to the energy in the 60-300 Kv range. 
         [0034]    As a fourth part  130  (see  FIG. 3 ) of the process, the computer processes the third image  80  to enhance an image  90  of the matter  65  by using an automated algorithm  95  as is known in the art residing in general purpose computer  25 . As known in the art, the computer  25  in conjunction with the x-ray detector  20  captures a number of counts of x-rays strikes in a pixel of the x-ray detector that relate to each portion of the part  15  as the part is bombarded over a given period of time. The unwanted matter  65  is not easily seen in the full x-ray spectrum image because the image is overwhelmed by the denser materials shown in  FIGS. 2A and 2B . Yet after the subtraction of the second image  75  from the first image  60 , the effects of the blade geometry can be eliminated (see  FIG. 2C  and graph  91 ). The unwanted matter  65  also may not show, without enhancement, if a full spectrum x-ray between 60 and 300 kilovolts is taken because the image data is overwhelmed by the attenuation characteristic of part  15 . 
         [0035]    As a fifth part  140  (see  FIG. 3 ) of the process, the part  15  such as blade  15  may be scrapped, repaired or reprocessed depending on the severity of the unwanted matter or defect  65  present. 
         [0036]    One of ordinary skill in the art will recognize that this process may be used in determining the presence of material that does not belong in an environment, such as the human body, or other bodies where harder materials that attenuate more may exist, e.g., as a stent. This process may require more exact manipulation of the breadth of the full x-ray spectrum and the hardened beams to allow for unwanted material to be seen. One of ordinary skill in the art will recognize that, while two dimensional images  60 ,  75  and  80  are shown herein, as technology advances, more than two dimensional images may be created and use the teachings herein. 
         [0037]    Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the Figures or all of the portions schematically shown in the Figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments. 
         [0038]    The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.