Patent Publication Number: US-2021190705-A1

Title: Radiographic inspection system for pipes and other structures using radioisotopes

Description:
Radiographic inspection systems may generate images of objects such as pipes and pipe welds. For example, a radiographic inspection system may be attached to a pipe to generate multiple images of a weld. A radioisotope may be exposed, and image may be captured, the radioisotope may be retracted, and a technician may move the radiographic inspection system to another position. The process may repeat until a desired number of images are generated. 
    
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1A-1B  are block diagrams of radiographic inspection systems using radioisotopes according to some embodiments. 
         FIG. 2A-2E  are block diagrams of an operation of a radiographic inspection system according to some embodiments. 
         FIG. 3-4B  are block diagrams of radiographic inspection systems using radioisotopes according to some embodiments. 
         FIGS. 5A and 5B  are block diagrams of operations performed on images from a radiographic inspection system according to some other embodiments. 
         FIG. 6  is a block diagram of a portion of radiographic inspection system according to some embodiments. 
         FIG. 7  is a block diagram of radiographic inspection system using radioisotopes according to some embodiments. 
         FIG. 8  is a flowchart of an operation of a radiographic inspection system according to some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Some embodiments relate to radiographic inspection systems and, in particular, to radiographic inspection systems for pipes and other structures using radioisotopes. 
     Pipe welds for a variety of different pipe diameters may be inspected using radiographic testing (RT). Examples of such pipe include about 1.5 inch (in.) to about 12 inch (about 3.81 to 30.5 centimeters (cm)) diameter pipe. The pipe may be initially welded during the construction of a facility such as a refinery or chemical plant. The welds may be inspected after the initial welding and/or at periodic inspection intervals, such as when the pipes are inspected for corrosion as may be required by a regulatory or quality assurance requirements. Conventionally, some RT methods use a radioisotope such as Ir-192 as a radiographic source and film to perform a Double Wall Single Image (DWSI) process where the radioisotope source is on one side of the pipe and the film is on the other. Double wall refers to the radiation from the radiographic source penetrating two walls of the pipe (e.g., the pipe wall closest to the radiographic source and the pipe wall closest to the film) before an image is acquired. The portion of the weld being inspected is the side closest to the film. The time for this type of imaging includes the technician placing the source collimator and film around the pipe, retreating to a safe distance to minimize radiation exposure before exposing the source, exposing the pipe for the correct time based on the pipe diameter and wall thickness, retracting the source, retrieving the exposed film for developing, and then moving the source and detector to achieve additional DWSI images of the weld for total coverage. The process may take 3 to 6 film shots to get full coverage and about 15 to 20 minutes of time. As a result, images for about 3-4 complete welds per hour can be completed. In addition, each film must then be reviewed on site and stored in a film repository or converted to digital format for digital storage. Some processes use a flexible phosphor imaging plate that is exposed. The exposed plate is scanned and digitized. 
     These techniques may be labor intensive and can limit throughput that is especially crucial during facility construction. Other systems designed for weld inspection may include x-ray tubes for DWSI as well as Single Wall Single Image (SWSI). SWSI is a technique whereby the radiographic source is placed inside the pipe by some suitable mechanism and the film wrapped around the outside of the pipe (or a portion of the pipe) and the radiation from the radiographic source on penetrate one wall of the pipe to acquire the image. SWSI with film wrapped around the entire outside of the pipe may be known as a panoramic exposure or imaging. However, a system that includes an x-ray tube will be a larger system to accommodate both the power and the weight, which may limit the applicability to large diameter pipes. The radioisotope source can be a much lighter than an x-ray tube generating similar x-ray or gamma ray energy. In addition, moving such a system to another weld location may require lifting equipment, such as a crane, with larger setup times. 
       FIG. 1A-1B  are block diagrams of radiographic inspection systems using radioisotopes as the radiographic source according to some embodiments.  FIG. 1A  is a cutaway view and  FIG. 1B  is a cross-sectional view along plane  1 B. Referring to  FIGS. 1A and 1B , in some embodiments, the radiographic inspection system  100  includes a detector  102 , a support  104 , a radioisotope collimator  106 , and a collimator support arm (CSA)  108 . A radioisotope  118 , exposure device  116 , exposure tube  114 , or the like may be part of and/or used with the system  100  to generate images based on the pipe  110  or other objects. 
     The detector  102  includes a two-dimensional imaging array  111  of sensors configured to sense the radiation  112  from a radioisotope  118  when disposed in the radioisotope collimator  106 . The detector  102  may include an amorphous silicon (a-Si), indium gallium zinc oxide (IGZO), or complementary metal-oxide-semiconductor (CMOS) flat panel detector, or the like. In other embodiments, the detector  102  may include a curved detector. In other embodiments, the detector  102  may include a flexible detector  102  that may be conformable to the curvature of the pipe  110 . In some embodiments, the curvature of the flexible detector  102  may be different than that of the pipe  110  to accommodate the detector  102  being radially offset from the pipe  110 . In other embodiments, the detector  102  may include a line scanner with a small number of pixels along the width relative to number of pixel along the length. Line scanners work well in continuous scanning applications or applications of continuous uniform movement of the detector  102 . 
     A conversion screen, scintillator, or the like may be included in the detector  102  to convert the radiation  112  into wavelengths detectable by the imaging array  111  of the detector  102 . For example, a scintillator may include gadolinium oxysulfide (Gd 2 O 2 S; GOS; Gadox), gadolinium oxysulfide doped with terbium (Gd 2 O 2 S:Tb), cesium iodide (CsI), or the like. Although some materials of the scintillator have been used as examples, in other embodiments, the material may be different depending on the particular radioisotope  118 . In other embodiments, the imaging array  111  may include direct conversion sensors, including cadmium telluride (CdTe), cadmium zinc telluride (CdZnTe or CZT), selenium, or the like, configured to directly convert the radiation  112  into a signal. 
     In some embodiments, a pixel area of the imaging array  111  of the detector  102  may be about 14.6×14.6 cm (or 5.8×5.8 in). The imaging array  111  may include a 1152×1152 array of pixels. The pixel pitch may be about 127 microns (μm). The detector  102  may be configured to digitize outputs of the pixels with at least 16-bit precision. The detector  102  may include communication interfaces such as a universal serial bus (USB) interface, Ethernet interface, or the like. Although particular components and parameters of the detector  102 , imaging array  111 , or the like have been used as examples, in other embodiments, the parameters may be different. 
     The detector  102  may include control logic  109 . The control logic  109  may include a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit, a microcontroller, a programmable logic device, discrete circuits, a combination of such devices, or the like. The control logic  109  may include external interfaces, such as address and data bus interfaces, interrupt interfaces, or the like. The control logic  109  may include other interface devices, such as logic chipsets, hubs, memory controllers, communication interfaces, or the like to connect the control logic  109  to internal and external components. The control logic  109  may be configured to control the variety of operations described herein. 
     The system  100  may be configured to operate with pipe  110  having a diameter from about 2 in. to about 12 in. (about 5 cm to 30.5 cm). In some embodiments, the range of pipe  110  diameter may be different. In some embodiments, the system  100  may be configured for a single pipe  110  diameter. In other embodiments, the system  100  may be adjustable so that the system  100  may be used with pipes  110  of a range of diameters. The pipe  110  may be ferrous or non-ferrous. In some embodiments, the use of an x-ray source may have difficulty due to refraction from alloy elements in some pipe. The use of a radioisotope  118  may reduce an effect of such alloys. 
     In some embodiments, the system  100  may weigh less than about 30 pounds (lbs.; about 13.6 kilograms (kg)), about 55 pounds (about 25 kg), or the like. The weight may be low enough that a single person may attach, operate, and detach the system  100  from the pipe  110 . For example, the detector  102  may weight about 6 lbs. or 2.7 kg. Motors, chains, structural components, or the like may be selected to keep the weight under the limits described above. 
     The support  104  is configured to attach the detector  102  to a structure such that the detector  102  is movable around the structure. Here, a pipe  110  is used as an example of the structure, but in other examples another structure may be used. In some embodiments, the support  104  is configured to rotatably couple the detector  102  to the pipe  110 . For example, the support  104  may include a chain belt, roller chain, a flexible structure, or the like wrapped around the pipe  110 . In a particular example, the chain belt may rotatably couple the detector  102  to the pipe  110  while a motor, wheels, or other structures maintain and/or rotates the position of the detector  102  around the pipe  110 . Here, a wheel  107  that contacts the pipe  110  may rotate the detector  104  about the pipe and/or hold the detector  102  in a particular position. In some embodiments, the support  104  rotates with the detector  102 ; however, in other embodiments, the support  104  may be a structure attachable to the pipe  110  and the detector  102  may rotate about the support  104  and consequently rotate about the pipe  110 . In some embodiments, the detector  102  and/or the support  104  may be configurable to place the detector  102  at a desired distance from the weld and/or the pipe  110  surface. For example, the support  104  may be configurable to place the detector  102  with a clearance of 0.35 in. (or 8.9 millimeters (mm)), clearance of 0.5 in. (or 1.27 cm), clearance of 1 in. (or 2.54 cm), relative to the weld  122  or pipe  110  wall. 
     In some embodiments, the support  104  may have an adjustable length. For example, a chain belt may have a sufficient length to encircle pipes  110  with a range of diameters, such as from about 1.5 in. to about 12 in. (or about 3.81 cm to about 30.5 cm). 
     The radioisotope collimator  106  is a structure configured to shape the radiation  112  from the radioisotope  118 . For example, the radiographic collimator  106  may include shielding to block radiation  112  emitted in undesirable directions and a collimating structure such as a series of parallel openings to shape the emitted radiation  112  when the radioisotope  118  is within the radioisotope collimator  106 . 
     The radioisotope collimator  106  may be rigidly and/or adjustably coupled to the detector  102  by the collimator support arm  108 . The collimator support arm  108  may provide zero or more degrees of freedom to position the radioisotope collimator  106  relative to the detector  102 . For example, the collimator support arm  108  may include a c-shaped arm that rigidly connects the radioisotope collimator  106  to the detector  102 . Such a system  100  may be designed for a single diameter of pipe. In other examples, the collimator support arm  108  may include multiple degrees of freedom to rotate and/or translate the radioisotope collimator  106  relative to the detector  102 . The collimator support arm  108  may be configurable to be fixed to rigidly (or semi-permanently) connect the radioisotope collimator  106  to the detector  102  after adjustment. Thus, the orientation of the radioisotope collimator  106  and the detector  102  may be fixed during that operation. However, for another operation, such as when the system  100  is moved to a different diameter pipe, the collimator support arm  108  may be adjusted to accommodate the difference in the pipe diameter. In some embodiments, the collimator support arm  108  may include a series of joints to adjust the position and orientation of the radioisotope collimator  106 . Regardless, the collimator support arm  108  may be configurable to be fixed after adjustment such that when the detector  102  moves around the pipe  110 , the relative position between the detector  102  and the radioisotope collimator  106  remains substantially the same. Substantially the same may include the same position but also includes some variation due to mechanical tolerances, distortion of the collimator support arm  108 , or the like. 
     Radioisotopes  118  may be more extensively used in field radiography than x-ray tubes in particular industries such as the oil and gas industry for reasons such as size, weight, power, cabling, accessibility, and/or energy requirements. With a system  100  described herein, the user may continue to use a radioisotope  118  with the improved performance of the system  100 . 
     The radioisotope  118  may be configured to be disposed in the exposure device  116 . The exposure device  116  may include a structure that allows for the radioisotope to be extended and retracted towards the radioisotope collimator  106 . For example, the radioisotope  118  may be coupled to a cable  120 . The cable  120  may be manipulated, such as by turning a crank, activating a motor, or the like, to move the radioisotope  118  through the exposure tube  114  to the radioisotope collimator  106 . The radioisotope  118  is illustrated in the retracted position in solid lines and in the exposed position in dashed lines. 
     When exposed, the radiation  112  travels through both walls of the pipe  110 , but only the portion  122   a  of the weld  122  on the wall closest to the detector  102  sufficiently sharp for inspection. That is, the portion  122   b  of the weld  122  may be in a position that does not result in a noticeable detected signal at the imaging array  111  and/or may be in a position where an intensity of the radiation  112  is reduced relative to the portion  122   a  due to the radioisotope collimator  106 . The radioisotope collimator  106  may be axially offset along the pipe  110  from the detector  102 . In an example, the axial offset may avoid the imaged radiation  112  penetrating at least the portion  122   b  of the weld  122  on the wall furthest to the detector  102  (the wall closest to the radioisotope collimator  106 ). The collimator support arm  108  may be configurable to place the radioisotope  118  in such a position for a variety of diameters of pipe. With the radioisotope  118  in place, the system  100  may rotate 360 degrees around the pipe  110  to inspect 100% of the weld. 
     In some weld imaging applications, a detector and an x-ray source may not be practical on pipes with diameters less than about 15 in. An x-ray source with sufficient energy may be too large to be placed around a relatively smaller pipe. An x-ray source that is small enough may not generate radiation with a sufficient energy to penetrate the pipe. That is, the radiation needs a sufficient energy to penetrate the pipe, depending on its size or the pipe schedule. An example of such an energy is 250 kilovolts (kV) or more. A radioisotope may provide radiation with this energy and still be relatively portable. 
     Some embodiments include a human portable inspection system that can be attached and removed easily. In particular, the human portable inspection system may be attached and removed by a single person. A human portable inspection system may include a system that weighs less than about 20 pounds (about 9.1 kg), less than about 25 pounds (about 11.4 kg), less than about 30 pounds (about 13.6 kg), less than about 45 pounds (about 20.4 kg), or less than about 55 pounds (about 25 kg). The system  100  is an example of such a human portable inspection system. 
     In some embodiments, the detector  102  is configured to receive power and/or communication through one or more cables  124 . In operation, as the system  100  rotates about the pipe  110 , the cables  124  may be wound around the pipe  110 . Thus, the cables  124  may be flexible enough and long enough to wind around the pipe  100  by at least one complete revolution. In particular, as no human intervention may be permitted during the operation as the radioisotope  118  may be continuously exposed, which generates high doses of radiation. 
     In some embodiments, the detector  102  may be configured to communicate wirelessly without using the cables  124 . For example, the detector  102  may include wireless communication systems  113  for operation with Wi-Fi, Bluetooth, cellular data networks, satellite communication networks, or the like. In some embodiments, the control logic  109  may be configured to communicate the images through the wireless communication system  113 . In other embodiments, the detector  102  may be configured to communicate through the cable  124  to a wireless communication system. Accordingly, data generated by the system  100  may be transmitted as desired to a variety of destinations and/or the control of the system  100  may be performed remotely. 
     As will be described herein, once the system  100  is secured to the pipe  110 , the radioisotope  118  is exposed. While the radioisotope  118  is exposed, the system  100  is rotated 360 degrees around the pipe  110  and the resulting digital images can be stitched together to present one image of the weld for evaluation. This composite image can be inspected on site or can be transmitted via network or satellite communication for evaluation by an offsite expert. The image along with any other metadata collected can then also be digitally stored. 
     In some embodiments, the imaging array  111  of the detector  102  may have an active area of a particular size. The control logic  109  may be configured to select an active area of the imaging array  111  that is smaller than the entire active area for the acquisition of images. In particular, the system  100  may be used with a variety of different objects such as a variety of different diameters of pipe  110 . For a smaller diameter of pipe  110 , a smaller active area may be used while a larger active area is used with a larger diameter of pipe  110 . The active area may not put an upper limit on the diameter of pipe  110 . Even if the entire active are is used, a smaller rotational step may be used during the acquisition of images to generate a composite image of a weld  122 . 
     In some embodiments, the detector  102  may have shielding for components that are separate from the imaging array  111 . For example, the energy range of the radiation  112  may be from about 280 kV to about 720 kV. The radiation  112  may have a variety of discrete energy peaks. The shielding may reduce the amount of radiation that reaches the control logic  109  or other components of the detector  102 , reduce one or more of the peaks, or the like. 
       FIG. 2A-2E  are block diagrams of an operation of a radiographic inspection system according to some embodiments. Referring to  FIG. 2A , a pipe  110  will again be used as an example of an object to be imaged; however, the system  100  may be used to image different objects. The system  100  may be installed on the pipe  110 . For example, the support  104  may be attached at one end to the detector  102 . The support  104  may be wrapped around the pipe  110  and attached again to the detector. 
     Adjustments may be made to secure the system  100 . For example, the support  104  may be adjusted to secure the detector  102  to the pipe  110 . A position of the detector  102  relative to the pipe  110 , such as a height, an orientation, or the like may be adjusted. 
     In some embodiments, the position of the radiographic collimator  106  may be fixed relative to the detector  102  and thus, its position may not be adjusted; however, in other embodiments, the position may be adjustable. As described above, the collimator support arm  108  may include multiple degrees of freedom that may be adjusted to align the radiographic collimator  106  such that the expected radiation  112  (as illustrated in  FIG. 1A ) may be incident on the imaging array  111  (as illustrated in  FIG. 1A ). 
     Referring to  FIG. 2B , the radioisotope  118  may be extended to the radiographic collimator  106 . As a result, radiation  112  may pass through the pipe  110 , a weld  122  (as illustrated in  FIG. 1B ), and be detected by the imaging array  111  of the detector  102 . An image of the weld  122  may be generated at this rotational position around the pipe  110 . 
     Referring to  FIG. 2C-2E , the system  100  may be rotated about the pipe  110 . Here, a 90 degree rotation is illustrated from figure to figure; however, in other embodiments, the angular change may be different, including smaller or larger. In particular, while the radioisotope  118  is generating the radiation  112  in the radioisotope collimator  106 , the detector  102  may be moved from position to position. At each position, an image is acquired. For example, a total of 10 images may be acquired, each equally spaced around the pipe  110 . Once a first image is acquired, the detector  102  may be rotated 36 degrees. Another image may be acquired at the new position. The rotation and acquisition may be repeated until images at each desired location are acquired. In some embodiments, an image may be acquired at the end in the position where the imaging started in  FIG. 2B . Once the last image is acquired, the radioisotope  118  may be retracted into the exposure device  116 . 
     In some embodiments, the radioisotope  118  may be exposed and retracted only once during a scan of the entire weld  122 . However, in other embodiments, the radioisotope  118  may be exposed and retracted more than once per weld  122 , but less than once per image. For example, the radioisotope  118  may be exposed, one half of the images are acquired, and the radioisotope  118  is retracted. The process may be repeated to generate images at all desired positions along the weld  122 . As the process may be performed for less than once per acquired image, the overhead of exposing and retracting the radioisotope  118  may be reduced. 
     In some embodiments, a check procedure may be performed. The check procedure may include acquiring a single image. The single image may be used to verify an acceptable Image Quality Indicator (IQI) detection, acceptable alignment, the visibility of lead indicators/numbers, or the like. In some embodiments, the IQI may include wires, a plaque with predrilled holes, or the like. The IQI may be placed near lead numbers placed around the pipe. The system  100  may be moved, the radiographic collimator  106  may be adjusted, or the like to adjust the relative positions until an acceptable image is acquired. 
     In some embodiments, a test scan may be performed without the radioisotope  118  being exposed. For example, the detector  102  may be fully rotated around the pipe  110 . In some embodiments, the detector  102  rotation may be stopped at each point where an image would be acquired in an actual scan. In some embodiments, the detector  102  may be rotated in a reverse direction to return the detector  102  to its initial state after the test scan is performed. 
     In some embodiments, an operational method may include acquiring data at a number of discrete locations with sufficient overlap such that magnification differences are minimized. As a result, stitching of the images to form a composite image may include translation and rotation to match the images rather than scaling, non-linear distortion, or the like. 
     In some embodiments, dwell time at a given location may be set to achieve a required contrast to noise ratio (CNR) via IQI detection. The dwell time may be determined through test images captured in a single rotational position. The dwell time may be manually or automatically adjusted to achieve the desired contrast in an image. 
     In some embodiments, the number of dwell points may be set by the circumference of the circle formed by the radiographic collimator  106  to the detector  102  divided by the useful active area to achieve the stitching or combining into a composite image described herein. 
     In some embodiments, another operational method may include acquiring data continuously as the system  100  rotates. For example, a single row of pixels of the imaging array  111  may be used to acquire one dimensional images as the system  100  rotates. In another example, the entire imaging array  111  may be used to sample the same point on the pipe via multiple detector pixels. The speed may be set to achieve the CNR as determined by the IQI&#39;s. The detector  102  data may be re-sampled into an arc of a circle to alleviate magnification differences from the different detector pixel locations. 
     In some embodiments, a scan time may be calculated based on isotope strength, pipe  110  diameter and wall thickness, and a stitching algorithm based on a defined active area of the panel and the pipe diameter. The scan time may be calculated based the dwell time, integration time, the number of frames to average, or the like. In addition, the dwell time may be based on achieving a particular image quality level, such as an ability to see a given wire of an IQI in the image. For example, when imaging a schedule  40  6 in. pipe with a 50 Curie radioisotope  118 , a desired image quality may be achieved with a gray count of 25000 counts with an integration time of 10 seconds. This information may be used to calculate the integration time for other radioisotopes  118 . As there is a linear relationship between integration time and gray count for a given Curie strength, the use of radioisotope  118  with a different Curie strength may be converted into a different integration time. 
     In some embodiments, the operation may include selection of pipe type and strength of the radioisotope  118 . The values may then be used to suggest parameters for the image acquisition. Using those parameters or parameters modified by a user, the image acquisition is performed, resulting in multiple images. The multiple images are then stitched and/or combined into a composite image. In some embodiments, the composite image may be annotated. While information may be embedded into the image through the use of lead elements adjacent to the weld, in some embodiments, metadata of the composite image may be annotated with such data and or other data related to the weld  112 , the scanning parameters, the pipe  110 , the radioisotope  118 , or the like. In some embodiments, the image data may be modified to annotate the composite image. For example, a crack, void, flaw, or the like in a pipe/weld may be identified and highlighted in the image data. 
       FIG. 3-4B  are block diagrams of radiographic inspection systems using radioisotopes according to some embodiments. Referring to  FIG. 3 , the collimator support arm includes a c-arm  108   a . The c-arm  108   a  may have a shape such that the system  100   a  may be position around a largest diameter pipe  110  for that system  100   a . The system  100   a  may be used with other, smaller diameters of pipe  110 . In some embodiments, the c-arm  108  is fixed to the detector  102  and the radiographic collimator  106 . As a result, the alignment of the detector  102  and the radiographic collimator  106  may not need to be adjusted. 
     Referring to  FIGS. 4A and 4B , the system  100   b  may be similar to the system  100  described above. However, in some embodiments, the collimator support art  108  may be adjustable. Here, a collimator support arm  108   b  with at least three degrees a freedom is illustrated. That is, the collimator support arm  108   b  may be adjustable at least by rotating three different joints  109 - 1 ,  109 - 2 , and  109 - 3 . Although three joints  109  has been used as an example, in other embodiments, more or less joints may be used. In addition, the joints  109  may include rotating and/or translating mechanisms. 
     The configuration in  FIG. 4A  illustrates a configuration where the support  104  is extended to about a maximum. Thus, the diameter of the pipe  110   a  may be at or near a maximum pipe diameter for the system  100   b . In contrast, the same system  100   b  may be adjusted to fit the smaller diameter pipe  110   b  illustrated in  FIG. 4B . In this example, a roller chain is used as the support  104 . A tail or excess of the roller chain  104 ′ may remain after attaching the system  100   b  to the pipe  110   b . In addition, the joints  109  of the support arm  108   b  may be adjusted so that the radiographic collimator  106  is disposed in a desired position relative to the pipe  110   b  and the detector  102 . 
     In some embodiments, one or more of the joints  109  may be electronically controllable. For example, one or more of the joints  109  may include actuators such as motors, solenoids, hydraulic or pneumatic cylinders, or the like configured to actuate the joint. The control logic  109  may be coupled to the actuators and configured to control the actuators to put the radiographic collimator  106  in a desired position. In some embodiments, the actuators may be controllable while the radioisotope  118  is exposed. The position of the radiographic collimator  106  may be changed based on feedback from acquired images to improve image quality, avoid the portion  112   b  of the weld  112 , or the like. 
     In some embodiments, the control logic  109  may include a memory storing information related to a position of the radiographic collimator  106  based on pipe diameter or other pipe characteristics. In other embodiments, the control logic  109  may be configured to receive such information through the wireless communication system  113  or cable  124  from the computer  190  or other system. 
     Referring back to  FIGS. 1A and 1B , in some embodiments, the system  100  is set-up. Lead markers may be placed close to the weld in a circumferential manner such that the markers appear in the acquired images. The system  100  may be attached to the pipe  110  in a location overlapping the weld  122 . The collimator support arm  108  may then be adjusted to position the radioisotope collimator  106  to generate an acceptable image. 
     The acquisition may be setup by, for example, selecting a type of pipe such as by diameter, schedule, or the like. Particular examples include selecting a 4 in. nominal size, schedule  40  pipe, or the like. A scan plan may be uploaded to the detector  102 . The scan plan may include parameters such as the type of pipe, radioisotope  118  strength, the curie strength, number of acquisitions/individual images, integration time, number of frames to average, position of actuators of the collimator support arm, or the like. In some embodiments, the configuration of the pipe may be used to automatically generate a scan plan and the associated parameters. 
     In some embodiments, an active area of the detector  102  may be changed based on the pipe diameter. For example, for larger pipes  110 , a larger area may be used. In some embodiments, the active area may be selected based on the radius of the pipe such that a deviation of the pipe from flat associated with the active area is less than a threshold, such as ¼ in. or a fraction of the separation of the detector  102  and the pipe  110 . In other embodiments, other criteria may be used to select the size of the active area. In a particular example, a 3 in. wide active area may be used with a 12 in. diameter pipe. In some embodiments, a larger active area may be used. The image may be post-processed to account for the curvature of the pipe relative to the detector  102 , such as a change in the magnification, relative intensity, or the like. 
       FIGS. 5A and 5B  are block diagrams of operations performed on images from a radiographic inspection system according to some other embodiments. Referring to  FIG. 5A , multiple images  502  may be acquired at different positions around an object. The images  502  may be combined into a composite image  504 . The dashed lines represent the borders of the individual images  502 . In the overlapping regions, the images may be combined in a variety of ways. For example, the data may be averaged in the overlapping region, combined using a weighted average depending on proximity to one or the other of the two images, or the like. Although some overlap has been used as an example, in other embodiments, the imaged may be tiled together without overlap. 
     Referring to  FIG. 5B , in some embodiments, the images  502  may be preprocessed before being combined as described above, For example, the curvature of the object, such as the curvature of a pipe wall, the relative intensity of the radiation  118 , or the like may be used to scale, distort, or otherwise transform the data of each image  502 . In some embodiments, the images may be processed to normalize the images to represent an image taken as if the imaging array  111  followed the contour of the object and a substantially uniform radiation source was used to illuminate the imaging array  111 . 
     In a particular example, the radiation source  118  and the radioisotope collimator  106  produces radiation  112  which may induce a bright center somewhere in the middle of the image. This radiation  112  may have a circular or elliptical shape and decreases in intensity towards the border of the image  502 . When stitching two adjacent images together, these images may have an overlapping region with an incline in one image and a decline in the other which may increases a difficulty when applying any cross correlation procedure to obtain the degree of overlap of the two images. 
     In some embodiments, an operation to subtract the beam profile from each image may be performed. For example, the operation may assume that the intensity of the radiation source drops off exponentially as described in equations 1 and 2. 
         p ( x,y )=be −ar   (1)
 
         r =√{square root over ( z   2 +( x−x   max ) 2   +e   2 ( y−y   max ) 2 )}  (2)
 
     Variables x and y denote the position of each pixel of the image (matrix). In an example, x and y range from 1 to 1152; however, the values may change based on the detector  102  and other processing. The 6 quantities a, b, e, x max , y max  and z need to be determined for each image taken. x max  and y max  denote the maximum position of the beam profile on the image coordinate system. z denotes the distance of the source and is orthogonal to the image plane. e stands for the ellipticity of the beam profile. The profile may be assumed to be elongated only in the x- or y-direction. a and b are arbitrary constants which describe the exponential fall off. However, a is usually rather small relative to b with a being about 0.001 and b on the order of about 1. To determine the 6 unknown quantities a nonlinear regression fit may be computed with equation 3. 
       χ 2 ( a,b,e,x   max   ,y   max   ,z )=Σ i,j ( p   i,j   −p ( x   i   ,y   j ) 2 )  (3)
 
     Here p i,j  is the intensity of each pixel of the image. To find the maximum likelihood parameter estimation of the 6 parameters we may find the minimum of the 2-fit which is given by equations 4-9. 
     
       
         
           
             
               
                 
                   
                     
                       ∂ 
                       
                         χ 
                         2 
                       
                     
                     
                       ∂ 
                       a 
                     
                   
                   = 
                   0 
                 
               
               
                 
                   ( 
                   4 
                   ) 
                 
               
             
             
               
                 
                   
                     
                       ∂ 
                       
                         χ 
                         2 
                       
                     
                     
                       ∂ 
                       b 
                     
                   
                   = 
                   0 
                 
               
               
                 
                   ( 
                   5 
                   ) 
                 
               
             
             
               
                 
                   
                     
                       ∂ 
                       
                         χ 
                         2 
                       
                     
                     
                       ∂ 
                       c 
                     
                   
                   = 
                   0 
                 
               
               
                 
                   ( 
                   6 
                   ) 
                 
               
             
             
               
                 
                   
                     
                       ∂ 
                       
                         χ 
                         2 
                       
                     
                     
                       ∂ 
                       
                         x 
                         max 
                       
                     
                   
                   = 
                   0 
                 
               
               
                 
                   ( 
                   7 
                   ) 
                 
               
             
             
               
                 
                   
                     
                       ∂ 
                       
                         χ 
                         2 
                       
                     
                     
                       ∂ 
                       
                         y 
                         max 
                       
                     
                   
                   = 
                   0 
                 
               
               
                 
                   ( 
                   8 
                   ) 
                 
               
             
             
               
                 
                   
                     
                       ∂ 
                       
                         χ 
                         2 
                       
                     
                     
                       ∂ 
                       z 
                     
                   
                   = 
                   0 
                 
               
               
                 
                   ( 
                   9 
                   ) 
                 
               
             
           
         
       
     
     Solving this nonlinear set of equations may use the Levenberg-Marquardt method which is a method that may be used for non-linear regression fits. In some embodiments, the exponential law may be cast into a semi-linear problem by applying the logarithm in equations 10 and 11 on equation 1. 
       ln( p ( x ))=− ar+{circumflex over (b)}   (10)
 
       {circumflex over ( b )}= ln b   (11)
 
     After determining the 6 parameters the beam profile may be subtracted as in equation 12. 
         p   no profile ( x,y )= e   ln p     i,j     −ln(p(x,y))   (11)
 
     This new obtained image is ready to be applied for combining with other images into a composite image. In some embodiments, the image may be combined by correlating features of the image such as numbers generated by a numbered lead strap around the pipe or other ICIs. As a result, the multiple images may be combined into a single image. The single image may make an evaluation operation easier as only one image would need to be stored retrieved, managed, or the like. 
       FIG. 6  is a block diagram of a portion of radiographic inspection system according to some embodiments. The radiographic inspection system  600  may be similar to the radiographic inspection system  100  or the like described above. Here, the radiographic inspection system  600  includes an elevation adjustment mechanism  640 , which may be manually, automatically, or electronically adjusted. The elevation adjustment mechanism  640  includes a first structure  650  and a second structure  652  that are movable relative to each other and may be fixed relative to each other. For example, in some embodiments, the elevation adjustment mechanism  640  may include a linear gear  660  attached to the first structure  650 . A gear  662  may be attached to the second structure  652  and disposed to mesh with the linear gear  660 . A shaft  654  with an adjustment knob  656  may allow for movement of the first structure  650  relative to the second structure  652 . Although an adjustment knob is shown in  FIG. 6 , in other examples, the elevation of the elevation adjustment mechanism may include actuators such as motors, solenoids, hydraulic or pneumatic cylinders, or the like configured to operate the gears. The control logic  109  may be coupled to the actuators and configured to control the actuators to adjust the elevation adjustment mechanism move the radiographic inspection system to a desired elevation. 
     When the radiographic inspection system  600  is attached to a pipe  110 , the support  104  (not illustrated) may attach the detector  102  including the elevation adjustment mechanism  640  to the pipe  110  such that wheels  107  may move the detector  102  around the pipe  110 . The first structure  650  may be rigidly coupled to the wheels  107 . As a result, a separation of the first structure  650  to the pipe  110  may remain substantially the same. However, as the second structure is movable relative to the first structure  650 , the second structure  652  may be moved relative to the pipe  110 . The imaging array  111  of the detector  102  may be attached to the second structure  652  such that its relative distance to the pipe  110  may be adjusted. This may allow for greater precision in positioning the detector for a given pipe  110 . A locking system  658  may lock the detector  102  in place after adjustment. 
     Although particular examples of structures that allow for the adjustment of the relative position of portions of the detector  102  to the pipe  110  or other object have been used as examples, in other embodiments, different structures and/or mechanisms may be used to alter the relative position. 
     Referring back to  FIGS. 1A and 1B , in some embodiments, the system  100  may be configured to receive power from a mains power source, such as a 110/220V power source. For example, the power may be provided through the cable  124 . In other embodiments, the system  100  may be configured to receive power from a power source  192  such as a portable power source, a battery, an inverter, or the like. In yet other embodiments, the system  100  may include an internal power source, such as an internal battery. 
     In some embodiments, the system  100  may include a computer  190  that may communicatively couple to the system  100 . Examples of such devices include a tablet, a desktop computer, a workstation, a mobile device, or the like. Such a device may be configured to receive individual images, combine the individual images into a combined image of an entire weld, receive a combined image, transmit the individual and/or combined images, or the like. In some embodiments, the control of operations may be distributed between the computer  190  and the control logic  109 . 
     In some embodiments, remote analysis may be performed. The individual images and/or combined image may be transmitted to a remoted location. An operator at the remote location may evaluate the weld. In addition to or in place of being remotely accessible, interpretation may be performed locally at the computer  190 . In other embodiments, multiple sets of images for multiple welds or other structures may be collected and transmitted/evaluated in bulk. 
     In some embodiments, the computer  190  may provide a graphical user interface (GUI). The GUI may graphically show the current position and thumbnails of the images acquired for user to see progress and status. The GUI may also provide fields to enter the various parameters described above. The GUI may also display a stitched composite image. However, in other embodiments, the composite image may be formed by a different system. 
     In some embodiments, the system  100  may be translated axially along the pipe  110 . The system  100  may be rotated partially around to fully around the pipe  110  while translating. The at least partial rotation may result in a full inspection of the pipe section, critical area, or the like. In particular, a portion of the pipe  110  may be corroded, the translation and rotation may allow for coverage of such a portion. In particular, although a weld  122  has been used as an example, other structures of an object may be imaged. 
     In some embodiments, a relatively larger detector  102  or with translation of a relatively smaller detector  102 , the images may be used to perform computed tomography. As a result, 3-dimensional information of welds  122  and corrosion including depth information of any identified flaws, or the like may be generated. 
       FIG. 7  is a block diagram of radiographic inspection system using radioisotopes according to some embodiments. The radiographic inspection system  700  may be similar to the radiographic inspection system  100  described above. However, the radiographic inspection system  700  may not include a radiographic collimator  106  attached to the detector  102 . In contrast, the radiographic collimator  106  may be a separate structure that is placed inside the pipe  110  such as through an access port  780 , and end of the pipe, or the like. In some embodiments, the radioisotope is configured as a panoramic source. In other embodiments, a radiographic collimator  106  may be placed inside the pipe  110  and the radiation  112  may be collimated as described above. With the radiographic inspection system  700 , a single wall single image (SWSI) may be formed. Similar to operations described above, the radioisotope  118  may be exposed and images may be created by rotating the detector  102  around the pipe  110 . The radioisotope  118  may be exposed and retracted only once or less than once per image as described above. As a result, the operation may be performed more efficiently. 
     In some embodiments, the pipe  110  may be a schedule  40  pipe with diameters from about 1.5 in. to about 12 in. Such pipes  110  may have wall thicknesses ranging from about 0.145 in. to about 0.5 in. The actual outer diameters may range from about 1.9 in. to about 12.75 in. 
     In some embodiments, an integration time or dwell time for an image may be based on the type of pipe  110 . For example, the table below lists examples of integration times per frame with a 1 curie source and a number of frames to average for a given diameter of schedule  40  pipe. These parameters may be based on a targeted gray count of about 30000. 
     
       
         
           
               
               
               
               
               
             
               
                   
               
               
                   
                 Wall 
                 Outer 
                   
                   
               
               
                 Schedule 
                 Thickness 
                 Diameter 
                 Integration 
                 Number of frames 
               
               
                 40 
                 (in.) 
                 (in.) 
                 time/frame/Curie 
                 to average 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 3 
                 0.216 
                 3.5 
                 0.0103 
                 10 
               
               
                 4 
                 0.237 
                 4.5 
                 0.0152 
                 10 
               
               
                 6 
                 0.28 
                 6.625 
                 0.0281 
                 10 
               
               
                 8 
                 0.5 
                 8.625 
                 0.0419 
                 10 
               
               
                 10 
                 0.5 
                 10.75 
                 0.0735 
                 10 
               
               
                 12 
                 0.5 
                 12.75 
                 0.0850 
                 10 
               
               
                   
               
            
           
         
       
     
     In some embodiments, an enclosure of the detector  102  may be resistant to dust, water, heat, direct sunlight, or the like. The frame may be formed of aluminum. An extruded white plastic cover may minimize solar heating. Connectors such as push-pull connectors like LEMO® cable connections for power and data, flush with the enclosure body may protect cables from catching or snagging. An internal gasket may be used to resist liquid and dust intrusion. 
     The connection between the detector  102 , support  104 , collimator support arm  108 , radioisotope collimator  106 , exposure tube  114 , or the like may have quick connect features to allow quick separation for easier handling, faster movement from one location to another, or the like. In addition, the collimator support arm  108  may also have such quick connect features so that the number of degrees of freedom and/or type of joints may be changed as desired in the field. 
       FIG. 8  is a flowchart of an operation of a radiographic inspection system according to some embodiments. Using the system  100  of  FIGS. 1A and 1B  as an example, in  800 , the radiographic inspection system  100  is positioned on a structure. For example, the system  100  or the like described above may be placed on a structure such as a pipe  110  by securing a support  104  to the pipe  110 . In some embodiments, the operation may be performed by a single person. 
     In  810 , a radioisotope  118  is exposed. For example, the radioisotope  118  may be extended into the radioisotope collimator  106 . In  820  an image is acquired using a detector  102  positioned with the structure between the exposed radioisotope  118  and the detector  102 . The acquisition of an image may include the acquisition of multiple images that are averaged or otherwise combined into a single image. 
     In  830 , if an additional image is to be acquired, the detector  102  is rotated around the structure in  840 . If not, the radioisotope may be retracted in  850 . Once the desired number of images have been acquired, the imaged may be combined into a composite image in  860 . 
     Some embodiments include a radiographic inspection system  100 ,  100   a ,  100   b ,  600 ,  700 , comprising: a detector  102 ; a support  104  configured to attach the detector  102  to a structure such that the detector  102  is movable around the structure; a radioisotope collimator  106 ; and a collimator support arm  108 ,  108   a ,  108   b  coupling the detector  102  to the radioisotope collimator  106  such that the radioisotope collimator  106  moves with the detector  102 . 
     In some embodiments, the system  100 ,  100   a ,  100   b ,  600 ,  700  further comprises control logic  109  configured to rotate the detector  102  and the radioisotope collimator  106  around the structure. 
     In some embodiments, the control logic  109  is further configured continuously acquire data from the detector  102  as the detector  102  rotates. 
     In some embodiments, the control logic  109  is further configured to acquire a plurality of images from the detector  102 , and each image is acquired at a different rotational position. 
     In some embodiments, the control logic  109  is further configured to combine the images into a composite image. 
     In some embodiments, the control logic  109  is further configured determine at least one of a dwell time and a number of the images. 
     In some embodiments, the system  100 ,  100   a ,  100   b ,  600 ,  700  further comprises a wireless communication system  100 ,  100   a ,  100   b ,  600 ,  700 ; wherein the control logic  109  is further configured to communicate data from the detector  102  through the wireless communication system  100 ,  100   a ,  100   b ,  600 ,  700 . 
     In some embodiments, the control logic  109  is further configured to select an active area of the detector  102  less than an entire active area of the detector  102  for the acquisition of the images. 
     The system  100 ,  100   a ,  100   b ,  600 ,  700  of claim  2 , wherein the control logic  109  is further configured to generate scanning parameters based on at least one of the structure and a radioisotope. 
     In some embodiments, the collimator support arm  108   a  comprises a c-arm. 
     In some embodiments, the collimator support arm  108 ,  108   a ,  108   b  is adjustable. 
     In some embodiments, the support arm  108 ,  108   a ,  108   b  comprises at least two degrees of freedom. 
     In some embodiments, the support  104  comprises a flexible belt configured to attach the detector  102  to the structure. 
     In some embodiments, the flexible belt is further move with the detector  102  as the detector  102  moves around the structure. 
     A method, comprising: exposing a radioisotope; acquiring a plurality of images using a detector  102  positioned with a structure between the exposed radioisotope and the detector  102 ; rotating the detector  102  around the structure between the acquisition of at least two of the images; retracting the radioisotope only after completing the acquiring of the images. 
     In some embodiments, the method further comprises rotating the radioisotope around the structure with the detector  102 . 
     In some embodiments, rotating the detector  102  around the structure comprises rotating the detector  102  around the structure between the acquisitions of each sequential pair of the images. 
     In some embodiments, the method further comprises combining the images into a composite image. 
     In some embodiments, the method further comprises selecting a number of the images based on attributes of the structure. 
     Some embodiments include a system, comprising: means for generating images in response to radiation; means for collimating radiation; means for attaching the means for generating images in response to radiation to the means for collimating the radiation; and means for movably attaching the means for generating images in response to radiation to an object. Examples of the means for generating images in response to radiation include the detector  102 , imaging array  111 , and control logic  109 . Examples of the means for collimating radiation include the radioisotope collimator  106 . Examples of the means for attaching the means for generating images in response to radiation to the means for collimating the radiation include the collimator support arm  108 ,  108   a , and  108   b . Examples of the means for movably attaching the means for generating images in response to radiation to an object include the support  104 . 
     In some embodiments, the system further comprises means for means for combining a plurality of images from the means for generating images in response to radiation into a composite image. Examples of the means for means for combining a plurality of images from the means for generating images in response to radiation into a composite image include the control logic  109  and the computer  190 . 
     Although the structures, devices, methods, and systems have been described in accordance with particular embodiments, one of ordinary skill in the art will readily recognize that many variations to the particular embodiments are possible, and any variations should therefore be considered to be within the spirit and scope disclosed herein. Accordingly, many modifications may be made by one of ordinary skill in the art without departing from the spirit and scope of the appended claims. 
     The claims following this written disclosure are hereby expressly incorporated into the present written disclosure, with each claim standing on its own as a separate embodiment. This disclosure includes all permutations of the independent claims with their dependent claims. Moreover, additional embodiments capable of derivation from the independent and dependent claims that follow are also expressly incorporated into the present written description. These additional embodiments are determined by replacing the dependency of a given dependent claim with the phrase “any of the claims beginning with claim [x] and ending with the claim that immediately precedes this one,” where the bracketed term “[x]” is replaced with the number of the most recently recited independent claim. For example, for the first claim set that begins with independent claim  1 , claim  3  can depend from either of claims  1  and  2 , with these separate dependencies yielding two distinct embodiments; claim  4  can depend from any one of claim  1 ,  2 , or  3 , with these separate dependencies yielding three distinct embodiments; claim  5  can depend from any one of claim  1 ,  2 ,  3 , or  4 , with these separate dependencies yielding four distinct embodiments; and so on. 
     Recitation in the claims of the term “first” with respect to a feature or element does not necessarily imply the existence of a second or additional such feature or element. Elements specifically recited in means-plus-function format, if any, are intended to be construed to cover the corresponding structure, material, or acts described herein and equivalents thereof in accordance with 35 U.S.C. § 112 ¶6. Embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.