System and method for internal inspection of rail components

An internal imaging system has a radiation source and a plurality of detectors positioned to receive portions of the plurality of collimated beams that have been attenuated by interaction with the target. The radiation source is configured to irradiate a target with a plurality of collimated beams of radiation. Two of the plurality of collimated beams of radiation may have different beam shapes. Another internal imaging system includes a radiation source configured to irradiate a target with at least one collimated beam of radiation and at least one detector. A planar rotating collimator is positioned adjacent to the radiation source and is configured to form the at least one collimated beam. The at least one detector is positioned to receive attenuated portions of the at least one collimated beam. The radiation source may be or include a neutron source. The detectors may be or include a plurality of neutron converters.

BACKGROUND

Field of Disclosure

The embodiments described herein relate generally to the internal inspection of railway track components using x-ray and neutron imaging techniques. More particularly, the embodiments described herein relate to backscatter and transmission radiography techniques for internal inspection of railway track components.

Related Art

Currently, flaws in rails and other railway track components are detected through direct contact non-destructive methods, such as ultrasound, or through destructive methods. The negative consequences of the latter are obvious whereas the former may leave flaws undetected in the rail, or identify “false positives” when in fact no defect exists. One known way to detect these flaws is with a handheld ultrasound system.

Currently, some flaws may be detected using destructive methods. One such flaw is an under shell fracture in a rail that may not be detectable with known non-destructive method. Such a defect is important to find so as to prevent catastrophic rail failure leading to derailment of rail bound vehicles. Additional flaws may include Rail Base Corrosion (RBC). Although RBC can be found on any track, it is most prevalent in tunnels and/or where the track is electrified. This is due to the combination of the standing water and electricity flowing through the rail acting to rust and erode the rail-base at an increased rate.

Approximately 15.3% of all derailments between 2001 and 2010 were caused by broken rails or welds. The second most common cause of derailments accounted for only 7.3%, leaving the detection of rail flaws as the most significant factor for the reduction of train derailments. Known inspection methods may leave flaws undetected, leaving significant room for improvement.

SUMMARY

The present disclosure is directed to an internal imaging system and method that overcomes some of the problems and disadvantages discussed above.

An internal imaging system having a radiation source and a plurality of detectors. The radiation source is configured to irradiate a target with a plurality of collimated beams of radiation. At least two of the plurality of collimated beams of radiation may have different beam shapes. The plurality of detectors are positioned to receive portions of the plurality of collimated beams that have been attenuated by interaction with the target.

The plurality of detectors may include at least one transmission detector positioned to receive a target between the at least one transmission detector and the radiation source. The plurality of detectors may include at least one scatter detector positioned to receive radiation scattered by interaction with the target. The radiation source and the plurality of detectors may be mounted upon a vehicle. The vehicle may be a rail traversing vehicle. The radiation source may be or include a neutron source and the plurality of detectors may be or include a plurality of neutron converters. The plurality of collimated beams may include a rotating pencil beam and at least one fan beam. The at least one fan beam may be a plurality of fan beams. The rotating pencil beam may be positioned between two of the plurality of fan beams.

The system may include a collimating collar. The collimating collar may include at least one fan beam collimator, each of the at least one fan beam collimator having a channel shaped to form radiation passing though the channel into one of the at least one fan beam. The collimating collar may include a collimator wheel rotatably disposed around the radiation source. The collimator wheel may include a plurality of beam openings, wherein radiation passing through the plurality of beam openings as the collimator wheel rotates forms a rotating pencil beam.

The system may include a planar rotating collimator positioned adjacent to the radiation source and configured to form the plurality of collimated beams. The radiation source may include a fixed aperture having an opening shaped to form a first fan beam. The planar rotating collimator may include a pencil beam opening, wherein the first fan beam intersects a portion of the pencil beam opening.

A method of using an internal imaging system to inspect a target includes irradiating a target with a plurality of collimated beams of radiation. The plurality of collimated beams include a first beam having a first beam shape and a second beam having a second beam shape. The method includes detecting a strength of a portion of the first beam that has been attenuated by interaction with the target with at least one first detector, detecting a strength of a portion of the second beam that has been attenuated by interaction with the target with at least one second detector, and generating data relating to an internal characteristic of the target using the detected strengths.

The at least one first detector may include at least one transmission detector. The at least one first detector may include at least one scatter detector. The at least one second detector may include at least one transmission detector. The at least one second detector may include at least one scatter detector. The radiation source may be a neutron source and the at least one first detector and the at least one second detector may be neutron converters.

At least two of the plurality of collimated beams of radiation may have different beam shapes. The plurality of collimated beams may include a rotating pencil beam and at least one fan beam. The first beam may be a rotating pencil beam. The second beam may be a fan beam. The method may include determining an angular position of the rotating pencil beam. The method may include irradiating each of a plurality of targets with a plurality of collimated beams of radiation.

The method may include emitting radiation from a radiation source and receiving a portion of the emitted radiation into a channel of at least one fan beam collimator and forming at least one fan beam. The method may include rotating a collimator wheel having a plurality of beam openings and receiving another portion of the emitted radiation into the plurality of beam openings of the collimator wheel and forming a rotating pencil beam.

The method may include emitting radiation from a radiation source and collimating the emitted radiation to include a first fan beam. The method may include rotating a planar rotating collimator, the planar rotating collimator including a pencil beam opening shaped to intersect a portion of the first fan beam and form a rotating pencil beam. The method may include emitting radiation from a radiation source and collimating the emitted radiation to include at least one second fan beam. The planar rotating collimator may include at least one fan beam opening shaped to receive the at least one second fan beam when the at least one fan beam opening is aligned with the at least one second fan beam. The method may include producing a three-dimensional representation of the target from the data. The producing a three-dimensional representation of the target from the data may be at an off-site location.

Another internal imaging system includes a radiation source and at least one detector. The radiation source is configured to irradiate a target with at least one collimated beam of radiation. The radiation source is not an x-ray source. The radiation source may be a gamma source, neutron source, or other energy wave source. The at least one detector is positioned to receive attenuated portions of the at least one collimated beam.

The system may include a vehicle. The radiation source and the at least one detector may be connected or mounted to the vehicle. The vehicle may be configured to travel along a railway track. The radiation source may be a neutron source. The at least one detector may be at least one neutron converter. The at least one neutron converter may include a neutron scintillator. The at least one collimated beam may be a plurality of collimated beams. The plurality of collimated beams may include at least one fan beam and a rotating pencil beam. The at least one detector may include a transmission detector. The at least one detector may include a scatter detector.

An internal imaging system includes a radiation source, a planar rotating collimator, and at least one detector. The radiation source is configured to irradiate a target with at least one collimated beam of radiation. The planar rotating collimator is positioned adjacent to the radiation source and configured to form the at least one collimated beam. The at least one detector is positioned to receive attenuated portions of the at least one collimated beam.

The at least one collimated beam may be a plurality of collimated beams. The plurality of collimated beams may include at least one fan beam and a rotating pencil beam. The radiation source may include a fixed aperture having an opening shaped to form a first fan beam. The planar rotating collimator may include a pencil beam opening, wherein the first fan beam intersects a portion of the pencil beam opening. The fixed aperture may include an opening shaped to form at least one second fan beam. The planar rotating collimator may include at least one fan beam opening shaped to receive the at least one second fan beam when the at least one fan beam opening is aligned with the at least one second fan beam.

The system may include a vehicle. The radiation source and the at least one detector may be connected or mounted to the vehicle. The vehicle may be configured to travel along a railway track. The radiation source may be a neutron source. The at least one detector may be at least one neutron converter. The at least one neutron converter may include a neutron scintillator.

DETAILED DESCRIPTION

The embodiments described herein are directed to an internal inspection system for railway track components using x-ray and/or neutron radiographic technology. The internal inspection system, or at least a portion thereof, may be mounted to a rail traversing vehicle, such as a hi-rail, a rail car, a rail bound drone or an engine. The internal inspection system may be used alone or synchronized with a video scan or 4D camera scan to provide a surface scan which can correspond to the internal image. One such surface scanning system is the Aurora system from Georgetown Rail Equipment Company of Georgetown, Tex., and systems disclosed in U.S. patent application Ser. No. 14/599,757, filed on Jan. 19, 2015, and entitled “System and Method for Inspecting Railroad Ties” and published as U.S. Pat. No. 8,958,079, the disclosure of which is incorporated by reference in its entirety. The radiographic inspection and video or 4D camera scan may be synchronized by the use of a wheel encoder and/or GPS system. The GPS system may be used to locate a railway component. For example, GPS coordinates may be recorded during the inspection to facilitate later locating a damaged component for repair or replacement. The video scan may provide color images or grayscale images. Alternatively, a comparison, such as a side-by-side comparison, of the radiographic scan and a surface scan may be used to analyze railway components instead of super-imposing the surface scan onto the backscatter x-ray scan.

The present disclosure is directed to detecting problems and flaws in railway track components through non-destructive means. Other than rail inspection, it is anticipated that the system and method disclosed herein would be beneficial to detect flaws in, among other things, joint bars, switches, plates, fasteners, spikes, bridges, and tunnels. This system may be used in both installed rail environments such as active railroads, and mill environments where products are created.

The embodiments disclosed may be used to inspect, for example, material density; the length of cracks, voids, or other internal flaws; the width of cracks, voids, or other internal flaws; the height of cracks, voids, or other internal flaws; the volume of cracks, voids, or other internal flaws; and/or composition of composite materials. Additionally, the radiographic techniques may be used to determine other aspects of railway components. For example, radiographic techniques may be used to determine if spikes are cut below the plate, determine if reinforcing structures show signs of fatigue or decomposition, show material decomposition, and/or calculate structural support of an object. Collected data may be used to identify and/or analyze additional railway component features as would be recognized by one of ordinary skill in the art having the benefit of this disclosure. Additionally, neutron imaging technology may be used to determine other aspects of railway components that may not be able to be detected using x-ray technology. For example, neutron imaging technology may be used to determine the rust formation on a surface of a railway track component.

The internal inspection system may incorporate x-ray and neutron radiographic imaging techniques, or a combination thereof, to detect flaws in railway components more thoroughly and at an acceptable rate of speed than known systems and methods. The radiographic imaging techniques may be applied in multiple orientations and the results may be used to reconstruct or represent three-dimensional images of the same railway track components. The radiographic imaging techniques may include transmission radiography and scatter radiography. Scatter detectors, transmission detectors, or combinations thereof may be positioned around a target to be inspected. The detection of scattered radiation and transmitted radiation may be used together, as will be appreciated by one of ordinary skill in the art having the benefit of this disclosure.

Transmission radiography uses a radiation source, such as an x-ray source or neutron source, in conjunction with a transmission detector placed on an opposing side of the intended target. Transmission detectors are configured to receive radiation that has passed through the target. Radiation is emitted from the radiation source, passes through the target, and is received on the opposite side of the target by the transmission detector. The strength of the signal passing through the target is interpreted and used to analyze the target. Transmitted radiation may be used to determine the composition and density of materials, as well as the presence of cracks, voids, or other internal flaws.

Backscatter radiography uses scattered rays that bounce back from within the target. Backscatter radiography may use lower levels of energy than transmission radiography. In backscatter x-ray methods, a scatter detector receives some of the rays that bounce off the object. The scatter detectors are configured to receive scattered radiation corresponding to a particular element of the target. The strength of the signal reaching the detector is then interpreted and used to analyze the target. Scattered radiation may be used to determine the composition and density of materials. In addition, scattered radiation may be used to determine the presence of cracks, voids, or other internal flaws.

Neutron radiography may provide advantages over x-ray radiography. For example, neutron radiography may be used as a complementary non-destructive technique to x-ray radiography. However, unlike x-rays, neutrons interact with the nuclei of the atoms as they pass through. Neutrons may penetrate through heavy nuclides more easily when compared to x-rays. Neutrons may image the light nuclides and pass through heavy nuclides better than x-rays. Neutrons may also interact differently with different isotopes. As a result, x-ray radiography and neutron radiography may be capable of providing different information.

Neutron radiography uses a neutron source in conjunction with a neutron converter placed around the intended scanning target. The neutrons are emitted from the source, pass through and scatter off the target object. Highly collimated beam of neutrons attenuate when incident on the railway track components and are received by a converter. The strength of the signal reaching the converter is then interpreted and used to analyze the target. With respect to backscatter neutron radiography, the neutron converter may be positioned on the same side of the target object. The neutrons are emitted from the source and are scattered upon contact with the target. While a portion of the neutrons pass through the target with only minor deflection or without any deflection, some of the neutrons are deflected by the object back toward the neutron source. These deflected neutrons are received at the converter. The strength of the backscatter signal may be interpreted to analyze internal structure of the target. The backscatter neutron radiography may incorporate neutron diffractions and small angle scatterings to image the strain patterns in railway track components.

The neutron converter may be a neutron scintillator, such as a6LiF—ZnS, or a neutron detector, such as a neutron sensitive micro channel plate (MCP) glass doped with10B or Gadolinium offered for sale by NOVA Scientific of Sturbridge, Mass., or any other technology that converts neutrons to signals or pulses. The internal inspection system may include a charge coupled device (CCD) sensor and light reflection mirrors with an array of scintillation materials to produce either color or grayscale images. The neutron scintillator may be hydrogen rich organic scintillator,6Li enriched scintillator, and other scintillator technology that converts neutrons to light signals. The resolution of the scintillators may be about 50 μm. Other neutron scintillation materials may be used.

The signals or pulses of a neutron converter may be used to produce either color or grayscale images of an internal structure of a target. The internal inspection system may include an array of individual neutron converters that are collimated like MCP and used with neutron detectors. MCPs may have a resolution of about 10 μm. The distances between the neutron source, the target, and the neutron converters may be varied to increase or decrease the resolution. The internal inspection system may be configured to scan railway components at preselected track speeds. The system may be configured to permit an increase or decrease in speed during the scan. For example, the speed may be decreased to improve resolution of a particular component, if desired.

The neutron source may be any source capable of emitting neutrons, such as a neutron generator, an accelerator, or a radioisotope that emits neutrons. The neutron generator for the internal inspection system may be an about 2.5 MeV deuterium-deuterium (DD) neutron system with approximately 125 kV of acceleration voltage and approximately 8 mA of beam current. The neutron yield of the DD neutron generator may be about 109neutrons per second. Also, a deuterium tritium (DT) neutron generator may be used for higher energy neutrons of about 14.1 MeV. In one embodiment, the inspection system may use a 125 kV, 8 mA neutron generator. The total system power consumption may be less than 2000 watts. The total power of the inspection system may be adjusted dynamically to increase or decrease exposure, as selected for penetration into the target and/or safety requirements. The x-ray energy for an x-ray source may reach 3 MeV. In order to provide power for the radiographic system, a scanning vehicle may be equipped with a separate generator. More than one scanning unit may be used and additional power sources may be included.

The speed of the scanning system may depend on multiple factors including the quantity of scanning units, FOV (field of view), resolution, and the amount of signal returning to the detectors. An operator may select a smaller FOV with a coarse resolution for a faster scanning speed. The scanning speed may be varied by changing the resolution at the time of operation through a signal collecting unit (SCU) that is dynamically adjustable. The SCU is configured to collect and transfer the images or signals produced by the neutron converters. In some embodiments, the system may be used for a multiple pass system. The first pass may be a course scan and after identifying areas of potential concern, a second pass with a finer scan may be made. The SCU may be an array of CCD cameras or fiber optic cables.

FIG. 1shows a schematic view of an embodiment of the internal imaging system100having a beam generation system110, a detector system120, a signal collection unit (“SCU”)150, and a CPU160. The beam generation system110includes the radiation source111and a collimator112configured to collimate radiation from the radiation source111and irradiate a target with at least one beam of penetrating radiation. The at least one beam of radiation may be a fan beam, cone beam, pencil beam, other beam shape, or combination thereof. The at least one beam may be a plurality of beams. At least two of the plurality of beams may have different beam shapes. The radiation source111may be an x-ray source, gamma source, neutron source, or other energy wave source, as would be appreciated by one of ordinary skill in the art having the benefit of this disclosure. The radiation source111may be configured to irradiate multiple targets. The multiple targets may be multiple railway components, such as both rails of a railroad track. The detector system120includes at least one detector121positioned to receive radiation transmitted through or scattered by the target. The at least one detector121is configured to measure radiation from the radiation source111that has been attenuated by interaction with the target. The radiation source111of the beam generating system110and the at least one detector121of detector system120may be configured to receive a portion of a railway component, such as a rail, there between such that at least a portion of the at least one beam of radiation pass through the railway component and are received by the at least one detector121. The at least one detector121may be directed toward the railway component such that at least a portion of the radiation emitted from the radiation source111that is scattered by interaction with the railway component is received by the at least one detector121. The at least one detector121may be positioned to receive scattered radiation in numerous directions. The strength of the signal received by the at least one detector121may be interpreted to analyze the internal structure of the target. The system100may further include any of the systems or structures described herein, for example, one or more other imaging or scanning systems130. The other imaging system130may provide a surface scan, as described above.

At least a portion of the system100may be mounted to or receivable by the vehicle105. The vehicle105may be confined to travel along a predefined path. The vehicle105may be a rail traversing vehicle, such as a hi-rail truck, adapted to travel along the rails of a railway. The inspection system100may be mounted or otherwise connected to the vehicle105in various ways, such as to the front of the vehicle105or the back of the vehicle105. The inspection system100may be mounted in or upon the vehicle105and directed beneath the vehicle105. The radiation source111of the beam generating system110may be positioned with sufficient clearance to avoid obstacles located on the path of travel. The distances between the radiation source111, the target, and the detectors121may be varied to increase or decrease the resolution. The position of the radiation source111and a detector121may be adjusted to limit inspection to an area of interest, such as a specific railway component or a portion of the railway component. The inspection system100may include collimators122configured to limit the field of view of a detector121. The inspection system100may include shielding135configured to absorb scattered radiation that may otherwise escape the system in an unintended direction.

The beam generation system110and the detector system120may include a transmission x-ray scanning system, a backscatter x-ray scanning system, a transmission neutron radiography scanning system, a backscatter neutron radiography scanning system, or a combination thereof. In a transmission x-ray scanning system, the radiation source111includes an x-ray source and the at least one detector121includes an x-ray transmission detector positioned to receive an attenuated portion of an x-ray beam after it has passed through the railway component. In a backscatter x-ray scanning system, the radiation source111includes an x-ray source and the at least one detector121includes at least one x-ray backscatter detector positioned to receive radiation that has been scattered by interaction with the railway component. In some embodiments, the internal imaging system100includes both a transmission x-ray scanning system and a backscatter x-ray scanning system. In some embodiments, the transmission x-ray scanning system and the backscatter x-ray scanning system may share at least one x-ray source or at least one detector.

In a transmission neutron radiography scanning system, the radiation source111includes a neutron source and the at least one detector121includes a neutron transmission converter positioned to receive an attenuated portion of a neutron beam after it has passed through the railway component. In a backscatter neutron radiography scanning system, the radiation source111includes a neutron source and the at least one detector121includes at least one neutron backscatter converter positioned to receive radiation that has been scattered by interaction with the railway component. In some embodiments, the internal imaging system100includes both a transmission neutron radiography scanning system and a backscatter neutron radiography scanning system. The transmission neutron radiography scanning system and the backscatter neutron radiography scanning system may share at least one neutron source or at least one neutron converter. In some embodiments, the internal imaging system100includes both x-ray and neutron sources. A single radiation source may provide multiple beams of radiation. The internal imaging system100may include additional radiation sources directed to other railway track components, such as the other rail, for inspection.

In some embodiments, the internal imaging system100further includes a controller140to initiate operations as described herein. The controller140may include one or more processors141and one or more memories142. The one or more memories142may store instructions that, when executed by the one or more processors141, cause the one or more processors141to initiate the operations. The operation may include controlling at least one of the beam generation system110and the detector system120. The operations may include receiving information from at least one of the beam generation system110and the detector system120. The operations may include initiating scanning of a selected railway component.

The internal imaging system100may include a signal collection unit (SCU)150configured to collect and transfer the images or signals produced by the detectors121. The SCU150may also collect and transfer images produced by the other imaging system130. The SCU150may be an array of CCD cameras or fiber optic cables. The detector signals may be synchronized with a location by the use of a wheel encoder and/or GPS system. The internal imaging system100may include at least one computer processing unit (CPU)160in communication with the detectors121through the SCU150. In some embodiments, the controller140may be integral to the CPU160. Data is generated as each of the detectors121detects the transmitted or scattered radiation. This data may be a pixelated internal image or a signal from the detector121. The CPU160receives the data from the detectors121through the SCU150and the CPU160may analyze the data to determine potential flaws and/or defects within the target.

In some embodiments, the analyzing and processing may be performed on the same CPU160or a separate CPU in a different location from the detectors121. For example, the radiation source111of the beam generation system110and the detectors121of the detector system120may be mounted to a rail traversing vehicle105and collect data from the detectors121. The data from the detectors121may be stored and later processed off-site. In some embodiments, the data may be processed on-site. The CPU160may be programmed with various algorithms used to analyze the detection data and identify potential flaws and/or defects in the internal structure of the target. The CPU160may be in wired or wireless communication with the detectors121. Multiple CPUs160may be used to store and/or analyze data generated by the detectors121. A display or monitor170may be connected to the CPU160and an image may be displayed on the monitor170based on the data received by the CPU160. The monitor170may display the pixelated internal image or a reconstructed image of the target(s) for analysis and review by an operator and, in some embodiments, superimpose the internal image of the railway component on another image of the railway component. In some embodiments, the monitor170may be positioned within a cab of the vehicle105and be viewed by the operator during inspection.

FIG. 2shows a top view of an embodiment of a beam generation system200that includes at least one radiation source210. The radiation source210may be a neutron source. The radiation source210may be an x-ray source, gamma source, or other energy wave source, as would be appreciated by one of ordinary skill in the art having the benefit of this disclosure. The direction of travel of beam generation system200is indicated by arrow201. The radiation source210may include a collimator (not shown inFIG. 2) and produce at least one beam211of radiation. The at least one beam211may be a plurality of beams211of radiation. The radiation source210is positioned to direct the beams211of radiation into a railway component. Each beam211may be positioned perpendicular to or at an angle with respect to the railway component to be inspected. The railway component may be various railway components, such as a rail205. The beams211of radiation may be directed into a specific portion of the railway component, such as the head, base, or web of the rail205. The radiation source210may irradiate multiple targets, or multiple portions of the same target, at the same time, and may be moved along a path of travel to inspect and analyze the internal structure thereof.

The beams211of radiation may be fan beams, cone beams, pencil beams, other beam shapes, or combination thereof. The plurality of beams211may include at least two beams having a different beam shape. The plurality of beams211may include at least one fan beam and at least one pencil beam. The at least one fan beam may be a plurality of fan beams. As shown, beams211of beam generation system200may include one pencil beam230, a forward fan beam220, and a rearward fan beam225. Some embodiments may include more than two fan beams. The pencil beam230may be positioned between the forward fan beam220and the rearward fan beam225. The forward fan beam220may be directed at an angle α with respect to the normal of the rail205. The angle α may range from 0 to 45 degrees. The rearward fan beam225may be directed at an opposing angle β with respect to the normal of the rail205. The angle β may range from 0 to 45 degrees. In some embodiments, both the forward fan beam220and the rearward fan beam225are oriented in the same direction, but at different angles. The rotating pencil beam230may be directed at an angle γ with respect to the normal of the rail205. The angle γ may range from −45 degrees to +45 degrees. The total scan span angle between forward fan beam220and rearward fan beam225may be less than or equal to 90 degrees. The orientation and the intensity of the pencil beam230and the fan beams220,225may be adjusted to increase the resolution of the reconstruction. In some embodiments, the angle α of the forward fan beam220may be 45 degrees and the angle θ of the rearward fan beam225may be 30 degrees. As described below, data from multiple perspectives is recorded and used to reconstruct flaws within the target. As shown inFIG. 3, the beam generation system200generates a radiation profile250. The radiation profile250includes a forward fan beam profile260corresponding to the forward fan beam220, a rearward fan beam profile265corresponding to the rearward fan beam225, and a pencil beam profile270corresponding to the pencil beam230. As discussed below, the combination of a fan beam profile and a pencil beam profile may be advantageous to generate a localized set of information, as well as a broader set of information, to be used during reconstruction.

FIG. 4shows an embodiment of the beam generation system200and a detector system300configured to detect radiation that has been transmitted through a railway component, such as a rail205. As shown inFIG. 4, the angle α of the forward fan beam220, the angle β of the rearward fan beam225, and the angle γ (shown as zero degrees) of the pencil beam230of the beam generation system200are different fromFIG. 2for illustrational purposes. However, it is appreciated that the detector system200may also be used with the beam angles displayed inFIG. 2and described above. In operation, the beams211of radiation from beam generation system200are directed into rail205. The beams211include a forward fan beam220, the rearward fan beam225, and the pencil beam230. As the beams211of radiation are transmitted through the rail205, the beams211are attenuated. The detector system300may include transmission detectors310, scatter detectors311(shown inFIGS. 5 and 6), or combinations thereof. The transmission detectors310, such as x-ray transmission detectors and neutron transmission converters, are configured to measure an attenuated portion of the beams211of radiation. The transmission detectors310may be a bank of detectors positioned along the rail205to receive different portions of the beams211of radiation. The transmission detectors310may include a forward beam detector320, a pencil beam detector330, and a rearward beam detector325. As shown inFIG. 4, the pencil beam detector330is positioned to receive the attenuated portion of the pencil beam230, forward beam detector320is positioned to receive the attenuated portion of the forward fan beam220, and the rearward beam detector325is positioned to receive the attenuated portion of the rearward fan beam225. The strength of the signals from the transmission detectors310is interpreted and used to analyze characteristics of the target.

Each transmission detector310may include collimators configured to limit the field of view of the transmission detector310. For example, collimators326may be positioned between the rearward fan beam225and rearward beam detector325. As radiation of the rearward fan beam225passes through the rail205at angle α, the attenuated portion is received into the collimators326and passes to the rearward beam detector325. Scattered radiation from other beams may be absorbed or blocked by the collimators326from reaching the rearward beam detector325. The collimators321may be positioned between the forward fan beam220and the forward beam detector320. As radiation of the forward beam220passes through the rail205at angle β, the attenuated portion is received into the collimators321and passes to the forward beam detector320. Scattered radiation from other beams may be absorbed or blocked by the collimators321from reaching the forward beam detector320. The pencil beam detector330, which is positioned to receive the attenuated portion of the pencil beam230, may not include collimators. For example, if the pencil beam230is directed perpendicular to the rail205and the fan beams220,221are directed away from the pencil beam230, a collimator may not be needed. However, in some embodiments, collimators may be associated with the pencil beam detector330as would be appreciated by one of ordinary skill in the art having the benefit of this disclosure. The pencil beam detector330may be separated from the forward beam detector320and the rearward beam detector325by dividers331that absorb or block the type of radiation from the radiation source210.

FIG. 5shows an embodiment of the beam generation system200and a detector system300configured to detect radiation that has been scattered by interaction with the railway component. In operation, the beams211of radiation from the beam generation system200are directed into the rail205. The beams211include a forward fan beam220, the rearward fan beam225, and the pencil beam230. As the beams211of radiation are transmitted through the rail205, the radiation is scattered by elements of the rail205. The detector system300may include scatter detectors311, such as x-ray scatter detectors and neutron scatter converters, positioned to detect radiation that has been scattered. The scatter detectors311may be positioned along the rail205to receive different scattered portions of the beams211of radiation. The scatter detectors311may be positioned to receive scattered radiation in numerous directions. The scatter detectors311may include backscatter detectors312positioned adjacent to the beams211to receive backscattered radiation. Each scatter detector311may include collimators configured to limit the field of view of the scatter detector311. The strength of the signals from the scatter detectors311is interpreted and used to analyze characteristics of the target.

As shown inFIG. 5, some embodiments may include a second beam generation system202and additional backscattered detectors340positioned on the opposing side of the rail205from the beam generation system200. The additional backscatter detectors340are positioned to detect radiation that has been scattered from the second beam generation system202. In some embodiments, the radiation inspection system200and the second beam generation system202may be offset and/or have a radiation source of a different type.

FIG. 6shows an embodiment of the beam generation system200and a detector system300configured to detect radiation that has been scattered above the rail205. As shown, the scatter detectors311of detector system300may include a forward top scatter detector323, a middle top scatter detector333, and a rearward top scatter detector328positioned along the top of the rail205to receive different scattered portions of the beam211of radiation. The middle top scatter detector333may be separated from forward top scatter detector323and rearward top scatter detector328by dividers332that absorb or block the type of radiation from the radiation source210. The strength of the signals from the scatter detectors311is interpreted and used to analyze characteristics of the target.

FIG. 7shows an embodiment of a pencil beam system400configured to generate a pencil beam430. The pencil beam system400includes a radiation source410and a rotating aperture420. The pencil beam430is a narrow beam of radiation that may be used for illuminating discrete portions406of a target405. By illuminating only the portions406of the target405, the radiation dose may be reduced as well as produce a localized set of information for detectors or converters to receive. The amount of information captured using the pencil beam430is proportional to its speed relative to the target405being inspected. Higher speeds increase the distance between imaged portions406of the target405.

Radiation may be emitted from the radiation source410through a fixed collimator (not shown inFIG. 7) and through the rotating aperture420to form the pencil beam430. The fixed collimator and the rotating aperture420work in conjunction to direct radiation to the desired portions406of the target405. The fixed collimator restricts the emission of unwanted radiation. The rotating aperture420focuses and directs the radiation. The rotating aperture420includes openings421that collimate radiation into pencil beam430and direct the pencil beam430toward the target405. As the rotating aperture420turns in direction422, the pencil beam430is swept through all of the angles to illuminate the target405. This rotation can be a full revolution, or may be a back and forth motion. The rotational position of the pencil beam430is monitored by the system400and may use an electrical impulse, such as an encoder, to determine the angle of the pencil beam430as it is emitted from the radiation source410. The beam angle and information received by a radiation detector may be used to reconstruct the image from the series of angular illuminations. In some embodiments, the rotating aperture420may be a collimation collar520(shown inFIG. 8) or a planar rotating collimator620(shown inFIG. 15).

FIG. 8shows a cross sectional view of an embodiment of a beam generating system500having a radiation source510and a collimation collar520. The beam generating system500may be positioned aside a rail505of a railroad track506and direct radiation angularly downward toward the rail505. The beam generating system500is configured to direct at least one beam501of radiation into a railway track component, such as a rail505. The at least one beam may be a plurality of beams501. Radiation is emitted from the radiation source510and collimated by the collimation collar520. The plurality of beams501may include at least two beams having a different beam shape. The plurality of beams501may include at least one fan beam and at least one rotating pencil beam.

FIG. 9shows an embodiment of a beam generating system500having a radiation source510and a collimation collar520. The radiation source510may be an x-ray tube, gamma source, neutron generator, or other energy wave source. The collimation collar520includes at least one fan beam collimator530and a collimator wheel540. The collimation collar520may include a drive mechanism550configured to rotate the collimator wheel540. In some embodiments, the at least one fan beam collimator530is a plurality of fan beam collimators530. As shown, the collimation collar520may be configured to produce a rotating pencil beam and two fan beams. Each fan beam collimator530includes a channel532shaped to form radiation into a fan beam. The collimator wheel540includes beam openings547configured to produce a rotating pencil beam as collimator wheel540rotates.

FIG. 10shows an embodiment of radiation source510with a radiation aperture511and a housing512. A field of radiation is emitted from the radiation source510through the radiation aperture511of the radiation source510. The housing512of radiation source510is configured to absorb radiation from the radiation source510and permit radiation to be emitted from radiation aperture511.

FIG. 11shows an embodiment of a fan beam collimator530. The fan beam collimator530includes an inner profile531shaped to at least partially surround the housing512(shown inFIG. 10) of the radiation source510and may comprise a material that blocks or absorbs the type of energy being emitted from the radiation source510. Radiation from the radiation source510is received at the inner portion of the fan beam collimator530and directed radially outward. The fan beam collimator530includes a channel532shaped to collimate radiation into a fan beam. The channel532of the fan beam collimator530is defined by a first side533and a second side534. The angle θ between the first side533and the second side534defines the spread of the fan beam. A depth of the channel532of the fan beam collimator530defines the thickness of the fan beam. The channel532may be an open channel formed in the side535of the fan beam collimator530, as shown. A surface of an adjacent component, such as drive mechanism550(shown inFIG. 9), may assist to define the thickness of the fan beam when the channel532is an open channel formed in the side535of the fan beam collimator530. The slope of the channel532of the fan beam collimator530directs the angle of emission of the fan beam. The slope of channel532shown inFIG. 11is zero and radiation may be directed immediately outward. However, the slope of the channel532may cause the channel532to be formed through the fan beam collimator530. For example, as discussed above with respect toFIG. 2, the slope of the channel532of the fan beam collimator530may correspond to the angle α of the forward fan beam220or the angle β of the rearward fan beam225as would be appreciated by one of ordinary skill in the art having the benefit of this disclosure.

FIG. 12shows a partial view of an embodiment of a collimator wheel540having an inner profile544shaped to at least partially surround the housing512of the radiation source510(shown inFIG. 9). The collimator wheel540is configured to produce a rotating pencil beam. The collimator wheel540includes a plurality of alternating body portions541and aperture portions545. The aperture portions545and the body portions541may be integral to form an integral collimator wheel540. In other embodiments, the aperture portions545may mate with the body portions541. The aperture portions545and the body portions541may comprise a material that blocks the type of radiation being emitted from the radiation source510(shown inFIG. 9). The apertures portions545each include a beam opening547having a width548and a height549. Radiation from the radiation source510is received near the inner profile544of the collimator wheel540and emitted radially outward through the beam openings547. The spacing between the beam openings547of adjacent aperture portions545forms an interval angle and determines the resolution and the speed of image creation, including the number of times the target is illuminated per revolution. Larger beam openings547may be selected to increase signal by increasing the size of the illumination, and may decrease resolution. Smaller beam openings547may be selected to decrease signal but increase resolution. The aperture portions545and body portions541may include mounts, such as holes542, configured to connect the collimator wheel540to the driving mechanism550(shown inFIG. 13). As the driving mechanism550is operated, the collimation wheel540rotates about an axis substantially perpendicular to the emitted pencil beam501.

FIG. 13shows an embodiment of a driving mechanism550. The driving mechanism550is configured to connect to the collimator wheel540such that rotation of the driving mechanism550causes the collimator wheel540to also rotate. The driving mechanism550may include teeth551shaped mesh with teeth of a gear or belt (not shown). The driving mechanism550includes complimentary mounts552, adapted to connect with the mounts542of the collimator wheel540. In some embodiments, pins543(shown inFIG. 14) may rigidly connect the driving mechanism550to the collimator wheel540.

FIG. 14shows an exploded view of beam generating system500. The collimator wheel540is connected on both sides to driving mechanisms550via pins543. A driving gear or belt (not shown) may mesh with the teeth551of the driving mechanism550to rotate the collimator wheel540around the radiation source510. The radiation source510emits a field of radiation from its aperture511(best seen inFIG. 10) and toward the collimation collar520. As the beam openings547(shown inFIG. 12) of the collimator wheel540intersect the radiation field emitted from the radiation source510, radiation is collimated through the beam openings547and forms a rotating pencil beam. The fan beam collimators530are positioned on each side of the collimation wheel540. The fan beam collimators530may be fixed from rotation. Radiation from the radiation source510is received into the channel532(shown inFIG. 11) of the fan beam collimator530and collimated into a fan beam.

In some applications, railroad inspection applications require that certain height clearance thresholds be maintained. For example, the system may need to be compliant with at least one of the Association of American Railroads (AAR) plate F clearance envelope or the AAR plate C clearance envelop. Further, it may be desirable to position the center of a beam of radiation closer to the center of the rail in order to achieve a more desirable illumination perspective for reconstruction. However, the size and positioning of a collimator around a radiation source may hinder the placement of the radiation source and the relative position of the beam of radiation with respect to the rail to be inspected. For example, a rotating collimator may interfere with a crosstie, tie plate, or other object positioned on the track.

FIG. 15shows a cross sectional view of an embodiment of a beam generating system600including a radiation source610and a planar rotating collimator620. The beam generating system600is configured to direct at least one beam601of radiation into a railway track component, such as a rail605, of a railroad track606at a lower position relative to collimators positioned around a radiation source. The at least one beam601may be a plurality of beams601. The beam generating system600may more readily clear track obstacles than other collimator and may achieve a more desirable illumination perspective for reconstruction.

FIG. 16shows an embodiment of a beam generating system600including a radiation source610and a planar rotating collimator620. Radiation is emitted from the radiation source610and collimated by the planar rotating collimator620into a plurality of beams601of radiation. The plurality of beams601include at least two beams having a different beam shape. The plurality of beams601may include at least one fan beam and at least one rotating pencil beam. As shown, the planar rotating collimator620may be configured to produce a rotating pencil beam and two fan beams. The radiation source610is positioned adjacent the planar rotating collimator620and emits radiation toward the planar rotating collimator620in a direction substantially perpendicular to the axis of rotation of the planar rotating collimator620. The radiation source610may be an x-ray tube, gamma source, neutron generator, or other energy wave source.

In some embodiments, the planar rotating collimator620may be configured to produce only a rotating pencil beam, as would be appreciated by one of ordinary skill in the art having the benefit of this disclosure. In other embodiments, the planar rotating collimator620may be configured to produce only a fan beam or plurality of fan beams, and no rotating pencil beam, as would be appreciated by one of ordinary skill in the art having the benefit of this disclosure.

FIG. 17shows an embodiment of the radiation source610with a radiation aperture611and a fixed aperture plate630. A radiation field is emitted from the radiation source610through the radiation aperture611of the radiation source620. The aperture plate630is configured to collimate radiation from the radiation source610. The aperture plate630is received within the radiation aperture611. As radiation is emitted from the radiation source610, it is focused or “collimated” so that the radiation only moves in one general path from the radiation source610to the target605(shown inFIG. 15), thereby reducing undesirable scattered radiation from reaching the target605.

The aperture plate630is fixed to the radiation aperture611of the radiation source610. The aperture plate630comprises a material that blocks or absorbs the type of radiation being emitted from the radiation source610. For example, the aperture plate630may comprise lead and the radiation source610may be an x-ray source. The aperture plate630may comprise polyethylene and the radiation source610may be a neutron source. The aperture plate630includes a plurality of beam apertures shaped to collimate the field of radiation from the radiation source610into a plurality of beams. The beam apertures may be fan beam apertures632configured to produce fan beams612and pencil beam aperture633configured to produce fan beam613. The planar rotating collimator620(shown inFIG. 16) may further collimate and shape the fan beam613into a pencil beam and further focus fan beams612.

FIG. 18shows a partial view of an embodiment of a planar rotating collimator620. The planar rotating collimator620may be made of a material that blocks or absorbs the type of radiation being emitted from the radiation source610. The planar rotating collimator620includes a plurality of beam openings disposed around the planar rotating collimator620. The planar rotating collimator620may be configured to produce a rotating pencil beam and a plurality of fan beams. The beam openings of the planar rotating collimator620may include fan beam openings622and pencil beam openings623. The beam openings may be distributed around the planar rotating collimator620in a pattern. The pattern, location, shape, angle, curvature, and size of the beam openings may be selected to determine the resolution and speed of image creation. The quantity of the beam openings may determine how many times the target is illuminated per revolution and which portions of the target are illuminated. The shape, angle, curvature, and size of the beam openings correlate to resolution of the image and amount of signal broadcast. Larger beam openings may be selected to increase signal by increasing the size of the illumination, and decreases resolution. Smaller beam openings may be selected to decrease signal but increase resolution.

The pencil beam openings623may be angled with respect to the orientation of the fan beam613such that only a portion of the pencil beam opening623intersect the fan beam613(shown inFIG. 17) as the planar rotating collimator620rotates. In addition, the pencil beam openings623may include varying angles that extend along the length of the pencil beam openings623to further direct the portion of the fan beam613emitted from the pencil beam openings623.

In operation, the planar rotating collimator620is positioned adjacent to the radiation source610. The radiation source610emits a field of radiation out of its aperture611toward planar rotating collimator620. The aperture plate630, disposed within the radiation aperture611of the radiation source610, collimates the field of radiation into fan beams612and613(shown inFIG. 17. A portion of the fan beam613aligns with one of the pencil beam openings623in the planar rotating collimator620. As the planar rotating collimator620rotates, the position of the pencil beam opening623with respect to radiation beam613is changed. When first aligned, only a top portion of the fan beam613passes through an upper portion624of the pencil beam opening623. As the planar rotating collimator620continues to rotate, a lower portion of the fan beam613passes through a lower portion of the pencil beam opening623and the top portion of beam613is no longer aligned with the pencil beam opening623. The planar rotating collimator620continues to rotate until a portion of the radiation beam613passes through the lowest portion625of the pencil beam opening623. Further rotation of the planar rotating collimator620aligns the top portion of beam613with an upper portion624of an adjacent pencil beam opening623. Accordingly, the portion of beam613that passes through the pencil beam opening623sweeps the target, as described above, to produce a rotating pencil beam profile250(shown inFIG. 3).

The fan beams612from fan beam apertures632(shown inFIG. 17) are directed toward planar rotating collimator620. As the planar rotating collimator620rotates, the fan beam openings622may align with at least a portion of the fan beams612. The fan beam openings622further collimate the fan beams612into shuttered fan beams. The number and orientation of the fan beams apertures632of the aperture plate630and the number and orientation of the fan beam openings622of the planar rotating collimator620may be selected to achieve a desired beam profile.

FIG. 19shows a plurality of the beam generating systems600oriented to irradiate multiple portions of railway components, such as tie plates607, on a railroad track606. The plurality of beam generating systems600may be oriented to illuminate multiple sides of the railway component. Further, unlike the orientation of the generating system600shown inFIG. 15, the orientation of the beam generating systems600inFIG. 19might only use backscatter radiography, if a transmission detector is not positioned on the opposing side of the railroad component being inspected.

The internal inspection system100(shown inFIG. 1) may be used to detect and/or identify various flaws or anomalies within railway components. For example, the system100may be used to detect an under shell fracture705in a rail700as shown inFIG. 20or Rail Base Corrosion (RBC)710on a rail700as shown inFIG. 21.FIG. 22shows an example of a crack715in a head portion of a rail700used in a simulation.FIG. 23shows a pixilated gray-scale image of the rail700with the crack715in the rail700, as may be generated by the internal inspection system100.FIG. 24shows an example of a void720in the rail700used in a simulation.FIG. 25shows a pixilated gray-scale image of the rail700with the void720in the rail700, as may be generated by the internal inspection system100.

FIG. 26shows hot numbers725stamped on the web of the rail700.FIG. 27shows a pixilated gray-scale image of the rail700with the stamped numbers725on the web of the rail700, as generated by the internal inspection system100using neutron radiography. It is noted that the pixilated gray-scale image is a mirror image of the rail inFIG. 26.FIG. 28shows a protrusion730positioned on the web of the rail700.FIG. 29shows a pixilated gray-scale image of the rail700with the protrusion730on the web of the rail700, as generated by the internal inspection system100using neutron radiography.FIG. 30shows a pixilated gray-scale image of a turbine blade735positioned behind the rail700, as generated by the internal inspection system100using neutron radiography.

FIG. 31shows a cross sectional view of a defective the rail800used in simulations. The defective the rail800includes a head801having the head void805measuring 2 cm×1 cm and a web802having a web void810measuring 1 cm×1 cm.FIG. 32shows a signal chart900that was generated using a fan beam geometry. The chart900consists of transmission detector signals901, top scatter detector signals902, and backscatter detector signals903. The left side of the chart900shows readings from the base of the rail that extend towards the head of the rail on the right side of the chart900. Line905on chart900corresponds to the location of the head void805of the rail800(shown inFIG. 31). Line910on chart900corresponds to the location of web void810of the rail800(shown inFIG. 31). As shown, the transmission detector signals901yielded contrast results, while the top scatter and backscatter signals902,903provided less information. The transmission detector signals901include signals915corresponding to the head void805of the rail800(shown inFIG. 31), signals920corresponding to web void810of the rail800(shown inFIG. 31), and signals925corresponding to a rail having no defect. The energy levels of signals915at line905and signals920at line910indicate the presence of voids805and810in the rail800(shown inFIG. 31).

FIG. 33shows a signal chart1000that was generated using a pencil beam geometry. The chart1000consists of transmission detector signals1001, top scatter detector signals1002, and backscatter detector signals1003. The left side of the chart1000shows readings from the base of the rail that extend towards the head of the rail on the right side of the chart1000. Line1005on chart1000corresponds to the location of the head void805of the rail800(shown inFIG. 31). Line1010on chart1000corresponds to the location of web void810of the rail800(shown inFIG. 31). As shown, the transmission detector signals1001yielded better resolution than the transmission detector signals901(shown inFIG. 32) but provided a lower contrast compared to signals901of the fan beam geometry. Furthermore, the top scatter detector signals1002and backscatter detector signals1003may provide more useful information, such as three-dimensional position, than the top scatter and backscatter signals902,903of the fan beam geometry. The transmission detector signals1001include signals1015corresponding to the head void805of the rail800(shown inFIG. 31), signals1020corresponding to web void810of the rail800(shown inFIG. 31), and signals1025corresponding to a rail having no defect. The energy levels of signals1015at line1005and signals1020at line1010indicate the presence of voids805and810in the rail800(shown inFIG. 31).

FIG. 34shows simulated images of inspection of defects across an entire rail using a pencil beam.FIG. 35shows simulated images of inspection of defects across a rail head using a pencil beam.FIG. 36shows simulated images of inspection of defects across a rail web using a pencil beam.FIG. 37shows simulated 3D CT images1101of a defect1105in the head of a rail1100as may be generated by internal inspection system100(shown inFIG. 1). Initially, 2D images were generated by using a number of different image processing methods. A 2D image model was generated using transmission detector data alone and was able to identify defects as small as 1 mm in the web and 3 mm in the head. The 3D CT images1101were generated using combined data strings from both fan beam and pencil beam and signals from nine detectors. Using the combination of data strings from both fan beam and pencil beam, a 3D image reconstruction may be generated in real time.

FIG. 38shows a cross-sectional view of simulated models of a rail head1200, rail base1205, and backscattered radiation. Radiation1210is directed into the rail base1205at an angle and scattered by interaction with the rail base1205. The simulation shows the difference of the backscatter images between different surroundings, such as wood crosstie, concrete crosstie, ballast etc. A series of solid rail profile may be generated and used to normalize image processing and 3D image reconstruction.FIGS. 39-41shows backscatter images from a model rail containing defects in lower parts of a rail web using 0.2 cm collimation spacing and backscatter radiography.FIG. 39shows a scan of defects ranging in size from 0.1 cm to 1.0 cm positioned on the bottom of a rail base.FIG. 40shows a scan of defects ranging in size from 0.1 cm to 1.0 cm positioned 1.0 cm above the bottom of the rail base.FIG. 41shows a scan of defects ranging in size from 0.1 cm to 1.0 cm positioned 2.0 cm above the bottom of the rail base. As shown inFIGS. 39-41, larger defects, such as 3 mm or more, may be more easily shown from the backscatter images. In addition, defects closer to the surface may more easily be shown from the backscatter images.FIG. 42shows a generated 3D profile1300of three off-centered defects at the lower part of a web of a rail. After a number of image processing steps, the 3D profile1300shows that these defects are off center, the size of the defects, and the position of the defects. With additional correlations using data from fan beam and rotating pencil beam geometries, 3D image (CT) reconstruction may be used to identify both the size and position of defects within a railway component.

Although this disclosure has been described in terms of certain preferred embodiments, other embodiments that are apparent to those of ordinary skill in the art, including embodiments that do not provide all of the features and advantages set forth herein, are also within the scope of this disclosure. Accordingly, the scope of the present disclosure is defined only by reference to the appended claims and equivalents thereof.