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    • 专利摘要:
    method and apparatus for scanning a structure to detect changes in density between different parts of the structure, and method and apparatus for scanning a subsea pipeline to detect changes in density between different parts of the pipeline or to derive information about the contents of the pipeline. the invention describes satisfactory scanning methods and apparatus for scanning a pipeline or process container in which a beam of gamma radiation from a source is emitted by the container to be detected by an array of detectors which are each collimated to detect radiation through a narrow angle relative to the width of the emitted radiation beam.
    公开号:BR112014010526B1
    申请号:R112014010526-0
    申请日:2012-11-02
    公开日:2020-09-15
    发明作者:Christopher Bowdon；Paul David Featonby；James Stephen Howstan；Peter Jackson；Kenneth James；Emanuele Ronchi
    申请人:Johnson Matthey Public Limited Company；
    IPC主号:
    专利说明:

    [0001] The present invention relates to a method of scanning a structure to detect changes in density by detecting radiation emitted by a radiation source by a radiation detector.
    [0002] Methods of visualizing objects and animals by X-ray tomography and positron emission tomography are well known, particularly in the field of medical imaging for diagnostic purposes. US 4338521 describes an X-ray scanner for use in computed tomography that has a detector including an array of detector modules, including a plurality of photodiodes and a plurality of scintillator crystals and a radiation beam collimator to direct collimated radiation to the crystals scintillator. A beam in the form of an X-ray fan from an X-ray source is directed by a patient to be detected by the detector. The source and detector are rotated around the patient to provide the data from which a tomographic image can be constructed. In positron emission tomography (PET), a positron emitted by the decay of a radionuclide annihilates in contact with a suitable electron, causing the emission of two photons in the range of 511 keV in opposite directions. The detection of the direction of the gamma photons enables the estimation of the annihilation event site and thus the radionuclide within the patient. The PET scanner therefore incorporates an array of detectors that can detect gamma photons placed around a patient's body. An image of the relative concentration of the radionuclide in the body can be constructed from the number of photons detected at each detector.
    [0003] While these scanning methods are well developed and have become common for medical scanning, scanning a dense structure such as a pipeline presents difficulties because the density of the pipeline material is such that radiographic scanning must be done using gamma radiation that is enough energy to penetrate and pass through the structure so that at least some radiation can be detected after the beam has passed through the structure.
    [0004] Range scanning of structures such as distillation columns is a standard industrial diagnostic method for measuring changes in density to different parts of the structure, for example to determine the location and integrity of column trays or other internal structures within the column . Normally this type of scanning is performed with a single gamma source placed adjacent to the column to emit a beam of radiation through the column and a radiation detector placed on an opposite part of the column to intercept and measure the radiation that has passed through the column between the source and detector. The source and detector are moved normally so that different parts of the column can be scanned. The use of many different positions and more than one source or detector can provide enough data to generate density maps, or tomographies, of the structure being scanned, although the resolution is generally quite coarse. In order to generate higher resolution density maps, information from a much larger number of radiation paths through the structure must be used than is currently achieved with conventional column scanning methods.
    [0005] Inspection of pipelines to find flaws such as loss of wall, cracks or corrosion spots is an application in which it would be desirable to use radiation scanning. A known problem for the oil and gas production industry is the inspection of pipelines located underwater, in particular on the seabed. Inspection of the inside of the pipeline using 'pigs' is not always possible, for example when the pipeline has a different diameter. Out-of-pipe inspection can be performed using ultrasonic methods, although this is not satisfactory for pipelines having an insulation or cover. Gamma sweeping can produce useful information about density across a cross section of the tube. In order to produce information about the tube wall thickness at a resolution high enough to identify small flaws that may be present in the tube walls, a large number of radiation paths through the tube need to be scanned. In addition, if a fan-shaped radiation beam is to be used to scan the pipe, many of the radiation paths cross a rope from the pipe cross section and therefore through a relatively large amount of the pipeline wall material, requiring a relatively high power range source. In order to detect the gamma radiation that has passed through the structure it is necessary to use detectors of sufficient size and density to stop the gamma photons, so that they do not pass through the undetected detector. In order to maintain a high resolution, the collimation of the detectors has to be sufficient to significantly reduce the detection of gamma photons that have been spread in a different path than the direct path to a particular detector. Detectors need to be small enough to provide good spatial resolution. A large number of detectors are needed to achieve a reasonable measurement time. The use of heavy collimation in a large number of detectors requires a scanning device that is very heavy and thus rotation of the device in a controlled and precise manner around a large pipeline becomes very difficult. When the pipeline is horizontal, it becomes necessary to entrench the tube in order to allow sufficient space in which to move a sweeper and thus the use of a large device becomes expensive, particularly when the pipeline is located underwater. All of these considerations pose particular problems when applying high resolution X-ray tomography methods for scanning pipelines or other large structures with high energy gamma radiation.
    [0006] It is an object of the present invention to provide such a method, although the method of the invention may be useful for sweeping different pipeline structures and for use in locations including both dry and subsea locations.
    [0007] The present invention relates to a method of scanning a structure to detect its physical properties. In particular, the invention relates to a method of sweeping a long structure, such as a pipeline, to detect changes in its material density that can indicate variations in wall thickness caused by corrosion or erosion or to deduce information about the contents of the pipeline such as the formation of deposits or the nature of fluid flowing within the pipeline. Typically, the method and apparatus are concerned with measuring the density of a structure by detecting radiation emitted by a radiation source by a radiation detector.
    [0008] In accordance with the invention, we provide a method of scanning a structure to detect changes in density between different parts of the structure including the steps of: a) providing at least one source of gamma radiation, and a plurality of detector units capable of detecting said gamma radiation, each detector unit including: i. a radiation detector including a scintillator including a scintillating material and having a detector surface defined by its thickness t and height h, where t <h on the detector surface and having a depth d perpendicular to the detector surface at least 2t, ii. a photodetector to detect the light emitted by the scintillator in response to gamma radiation, and iii. a collimator placed between the scintillator and the radiation source; b) causing the source to emit gamma radiation along a predetermined radiation path to the detector, where the path passes through at least a portion of the structure; c) measure the number of gamma radiation photons detected by each of said detectors; d) calculate a density value for each photon measurement path detected by the detector associated with the respective path.
    [0009] According to the invention, we provide an apparatus for scanning a structure to detect changes in density between different parts of the structure including: at least one source unit including a source of gamma radiation and shielding material arranged to restrict the emission gamma radiation from the source unit: a plurality of detector units capable of detecting said gamma radiation, each detector unit including: i. a radiation detector including a scintillator including a scintillating material and having a detector surface defined by its thickness t and height h, where t <h on the detector surface and having a depth d perpendicular to the detector surface at least 2t, ii. a photodetector to detect the light emitted by the scintillator in response to gamma radiation, and iii. a collimator placed between the scintillator and the radiation source; and a data processing means for calculating a density value for each photon measurement path detected by the detector associated with the respective path.
    [00010] The apparatus of the invention is suitable for use in the scanning method of the invention, in which a targeted structure is scanned to detect changes in its shape or composition by passing radiation emitted by a radiation source through the structure and detecting radiation afterwards that went through the structure. The method works on the well-known principle that the amount of radiation attenuated or scattered by an object is related to the mass of material through which the radiation has passed. By measuring the amount of radiation detected by each path selected by the target structure, it is possible to calculate and / or compare the density of the structure along a radiation path with the density of the structure along a different radiation path. By "density value" we mean a value that represents the actual or relative density of the structure that is on a particular path from the source to a particular detector. The density value can take the form of several gamma photon counts or a normalized, smoothed or comparative number of gamma photon counts. Alternatively, the density value can be a value calculated from the number of gamma photon counts. The density value can be expressed graphically, including as an image or part of it. The relative dimensions of the radiation detector scintillators of the invention allow a plurality of scintillators to be placed in close proximity in order to achieve a high degree of spatial resolution of detected radiation so that characteristics of small portions of the structure can be detected with high precision. . The method is particularly useful for sweeping a regular structure such as a pipe, although the method and apparatus can be used to sweep other types of structure. In a particular embodiment of the invention, the scanning method is a method of detecting changes in the density of a pipeline wall. Use of this method enables faults such as voids, cracks, scale, gas hydrates or thinning to be detected. The change in density can be detected relative to adjacent portions of the pipe wall or relative to a reference value generated from a model pipeline or a calculated value.
    [00011] In the method of the invention, an array of detector units is mounted opposite at least one source of gamma radiation such that radiation is emitted towards the detector surfaces. The target structure to be scanned is able to be interposed between the source and the detector unit so that the radiation emitted by the source can pass along a plurality of paths through a portion of the structure and impact the detector surfaces. The source and detector unit can be moved relative to the target structure (or vice versa) in order to scan different portions of the structure. The main benefit of using a detector array is that different paths through the structure can be scanned simultaneously. Each path is shaped like a cone trunk, with the source at the apex and the detector surface of a detector at the base. Each detector in the array defines a different path by the structure so that the number of paths that can be scanned simultaneously is equal to the number of detectors in the array. The number of detectors in a detector array can vary from less than 10 to more than 100, for example up to 150, depending on the application for which the scanning method is to be used. In practice, the mass of shielding material required to shield and collimate a large number of detectors can provide a practical upper limit to the number that can be used.
    [00012] The source unit and the detector unit can be mounted on a support in fixed relation to each other or the detector unit can be movable relative to the source unit. It is highly preferred that the source unit and detector unit are mounted in a fixed relationship when the apparatus is in operation. This enables the apparatus of the invention to provide a precise and fixed alignment of source and detector units so that modulation of the counts measured by the detectors can be attributed only to the materials between the source and detector through which the radiation path passes. In this way, very small differences in the density of such materials can be detected, allowing the detection of minor flaws or changes in the thickness of an oil pipeline wall. The source and detector unit are preferably mounted so that the detector surfaces of each of the detectors form a tangent to an arc having the source as its source. The plurality of detector units are arranged in close proximity to each other. It is preferred that the array of detector units is arranged in the form of an arc having a radius centered on the center of the object or structure to be scanned. The detector unit design preferably minimizes the total distance on each detection path by each detector unit in order to make the arrangement of detector units as compact as possible, while maintaining sufficient collimation depth and a detector for efficient photon detection range on each route.
    [00013] In a preferred form of the invention, the source unit and detector units are mounted on a support that provides a means for the structure to be scanned, or a portion of it, to be located between the source unit and the detector unit . The support keeps the source unit and detector unit in a fixed, spaced apart ratio. The support therefore includes means for mounting at least one source unit and means for mounting a plurality of detector units on the support. The support can include a long portion or "arm" having first and second opposite ends to which said detector unit and support unit can be mounted or joined. The means for mounting a detector unit includes a detector housing attached to the support. The support, source unit, and / or detector housing can be formed as a single component or separate components that are joined together. The support must be strong enough to resist supporting and moving the detector and source units without deformation and sufficiently rigid to maintain a precisely fixed relationship between the source unit and detector housing, including any detector units housed therein. A satisfactory material for the support includes an aluminum alloy, which can be machined using known methods to form the shape required for the support.
    [00014] The detector housing is formed to house one or more detector units and to secure such units so that they do not move unintentionally during the operation of the apparatus. It is an important feature of the preferred apparatus that the detector units can be maintained in a fixed relationship to the source during use in a scanning method. The detector housing can be of such a size and shape to house several detector units at the same time, for example 2-100 units. The detector housing may include means for housing a detector unit in more than one position within the housing. The means may simply include a detector housing having sufficient space to accommodate a detector unit in more than one location within the housing. Means, such as guide rails or an engine, can also be included to move one or more detector units from a first location within the housing to a second location within the housing. A practical limit in resolving a scanning method using a detector array is that the spacing between each should be sufficient to allow a minimum required amount of shielding to ensure that each detector is adequately shielded from photons hitting a neighboring detector. Even when highly dense alloys are used for detector shielding, we find that a practical limitation in detector spacing is approximately arc arc. In one embodiment of the apparatus, the detector housing is of such a size as to allow a detector unit to be housed in at least two positions, displaced by a distance that is a fraction of the distance between the detectors. When the fraction is 0.5 of the detector spacing distance (0.5s), the resolution of the device can be doubled by performing a first scan when the detector array is in a first position in the housing and then repeating the scan when the array detector is in a second position in the housing, which is displaced from the first position by 0.5 s. If additional positions are provided, and or, the angular distance between them is reduced, additional scans can provide additional data to increase the resolution of the scan. The detector can be moved between any of at least two positions, for example by operating a power switch operated by a solenoid. The provision of means for securely locking the detector arrangement in a single position while sweeping is greatly preferred. Such means may include a pressure pin or protrusion engaging with an index hole for each of the desired positions.
    [00015] In a particularly preferred form, the apparatus including support, detector housing (including any detector unit therein) and source unit can be moved laterally and / or rotationally, relative to the structure and means are provided to effect such movement. Preferably, the source unit and detector units are rotated around the structure such that the radius of rotation has an origin within the structure, for example the origin can be approximately to the geometric center of the structure in the plane of rotation. Means for movement can include motorized or manual thrust and guide means such as rails, tracks, guide channels or location indicators, to guide the rotation path. Preferably the apparatus is provided with at least one track or rail, formed to conform to at least a part of the structure to be scanned. For pipeline sweeping, for example, one or more curved tracks can be provided so that the device can be moved along the tracks, for example by means of a worm gear drive or a stepper motor by turning a drive wheel spline, gear or cog to rotate the detector and source housing around the circumference of the structure. In a preferred form, the guide means is indexed, for example by providing notches in which teeth of a driving gear tooth can engage to effect movement of the scanner. The provision of indexed motion can provide a predetermined number of scan locations at known angular positions around the structure. Preferably, a means is provided to rotate the detector and source units around a circumference of the structure to be scanned. In the case of a cylindrical object, such as a pipeline, the detector and source units are rotated around the circumference of the pipeline. The scanning method is performed at a plurality of positions displaced radially around the structure so that density data can be acquired at a variety of angles across the structure.
    [00016] The guide means, for example lanes, can extend partially or completely around the pipeline. It is preferred to move the source and detector unit continuously around the structure in order to avoid problems, such as damage to the apparatus or slipping of the scanning system, associated with successively accelerating and braking the apparatus. More than one scan may be required to gather enough data to determine the structure properties, although the number of scans and the scan time are dependent on the density and mass of material by which the radiation must travel from the source to the detector units. Preferably, a continuous rotational movement around the structure at a relatively low rpm, for example at approximately 1 to approximately 20 rpm, especially from 1 - 10 rpm, is maintained during the sweeping operation. Therefore, in a preferred apparatus, a means such as a continuous track is provided to enable such movement. The guide means can be provided in more than one part, which, following the development of the device, is brought together and optionally joined, to form the desired swath length for sweeping. The source unit, detector unit, support and guide means can all be housed within a housing that is capable of surrounding at least part of the structure. The housing can have an open position in which it can be positioned around the structure and a closed position in which it is able to sweep the structure. The housing can take the form of an articulated pair or set of jaws that can be tightened to the structure to be swept.
    [00017] Energy can be recovered from the movement of the device by means of a dynamo, or the like, which can then be used to help energize the detectors or other operating systems of the device.
    [00018] Movement of the device may also involve lifting and / or sliding the device manually or by mechanical means, for example by means of a remotely operated vehicle (ROV). An ROV may be preferred for deploying and moving the device when deployed in remote or underwater locations. Linear movement, for example parallel to the axis of a pipeline or a container, can be achieved by means of a conveyor mechanism or by using a track or rails, or alternatively by external means such as a lifting device or ROV. The means of movement may include indexing, for example to a particular angular separation in order to provide a predetermined number of scanning locations at known positions around the structure. For an application such as sweeping a pipeline, the movement can be controlled by means of a programmed electronic control unit, for example to perform a predetermined timed movement or set of movements of the source and detector units relative to the pipeline. The movement can be rotational to sweep around the circumference of the pipeline and / or lateral to move axially along the pipeline.
    [00019] The apparatus may include a means of supporting the apparatus in proximity to the structure to be scanned. Such means may include clamps, which are capable of engaging the frame and supporting the scanner in one or more positions on the frame. The clamps can be operated manually, but mechanically operated clamps are preferred.
    [00020] The sparkling material is selected according to the properties of the radiation that is to be detected and the conditions under which the detector is deployed. In principle, any satisfactory sparkling material can be selected and many materials are known and commercialized for radiation detection. A high density material provides a greater ability to stop radiation at a given volume and consequently the scintillator can be made smaller than would be possible for a lower density material. A small scintillator is more stable, for example it is less likely to exhibit a temperature differential between different parts of the crystal. Smaller crystals transmit light more effectively requiring less energized photodetectors to be used. Of importance to the present application, a small scintillator may have a small detector surface and thus radiation traveling along a narrow path can be detected without a significant amount of incident background radiation or scattered radiation from the same or different paths. For the detection of gamma radiation, it is preferred to use a dense inorganic material so that the incident photons can be stopped using a detector as small as possible. Sparkling materials having a density> 5 and a high Z number (atomic number) are preferred. It is preferred that scintillators have a depth and density that enables them to stop> 80% of photons in the energy range of 662 keV. For use in applications requiring resistance to environmental conditions, especially humidity, a non-hygroscopic crystal scintillator should be selected. Especially preferred detectors for use with gamma radiation include BGO (bismuth germanate), CdWCU, LaBr3 (Ce), LYSO (lutetium-cerium-doped yttrium oxytortosilicate), LSO (cerium-doped lutetium oxyortosilicate) and CeU (cerium fluoride) cerium). When a mechanically robust detector is required, a crystal having no split plan can be preferred in order to increase its resistance to break following a thermal or mechanical shock.
    [00021] Each scintillator has a detector surface, which, in use, is arranged to intercept the radiation path so that the radiation strikes the detector surface. Other surfaces of the detector that are not arranged to be detector surfaces will be called non-detector surfaces. Although any part of a scintillator is normally capable of detecting photons, the designation in this specification of detector surfaces and non-detector surfaces refers to the arrangement of the scintillator in the detector unit to detect radiation from a source. The scintillator also has a surface by which light generated by the scintillator in response to photons striking the detector surface leaves the scintillator. This surface is referred to here as the collecting surface. The collecting surface is arranged in optical communication with the photodetector. The collecting surface can come into contact with the photodetector or can be separated from it by one or more light transmitters, in the form of a window, lens, optical fiber, light tube or optically coupling material, etc., made of a material that transmits the light generated by the scintillator to the photodetector. The collecting surface of the detector may have a similar cross-sectional area and shape to that of the photodetector window or it may be different. The detector itself can act as a light guide to pass a significant proportion of the light generated in the scintillator to the photodetector. In this context, the use of the phrase "significant proportion" means all of the light generated in the scintillator is passed to the photodetector, except for a proportion of light lost unintentionally due to the efficiency of light transmission being less than 100%.
    [00022] Each of the detectors includes a scintillator, normally supported in a satisfactory position so that the detector surface intercepts a path of radiation emitted by the source at a particular distance and at a particular angle to the source of radiation. It is a particular feature of the invention that the detector can substantially reduce the detection of scattered radiation and increase the accuracy with which radiation emitted by a source along a particular linear path is detected. The provision of a detector having a long shape in which t <h, more preferably <0.5 h, on the detector surface enables the detectors to be located in close proximity so that the spatial resolution of each detector is high. The depth of the detector contributes to the stopping efficiency of the detector so that a detector having a depth d perpendicular to the detector surface at least 2t, more preferably at least 5t, especially> 10t is preferred in order to stop and measure energetic photons.
    [00023] The smallest dimension of the scintillation detector surface is preferably between about 1 mm and about 10 mm. The smallest dimension is defined to be the thickness t of the material. More preferably, 1 mm <t <5 mm and in a preferred embodiment t is about 5 mm. Preferably, the detector surface is generally rectangular so that the surface area is defined as t x h, where h is in the range 5-100 mm. More preferably, 10 mm <h <50 mm and in a preferred embodiment h is about 25 - 40 mm. The scintillator depth d is in the range 10 - 100 mm. More preferably, 25 mm <d <75 mm and in a preferred embodiment d is approximately 40 - 60 mm.
    [00024] A material that is impermeable to radiation can cover a portion of the scintillator's detector surface to delimit the portion of the detector surface on which radiation may collide. The collimator can overlap and cover one or more crystal edges by up to about 5 mm.
    [00025] The detection of scattered photons is preferably furthermore reduced by preventing the detectable radiation from colliding on the detector surfaces that are not detector surfaces. This can be achieved typically by covering the non-detecting surfaces, except for the portion of the collecting surface in optical communication with the photodetector, with a material that prevents transmission of radiation to the non-detecting surfaces. In a preferred embodiment, the detectors are surrounded by shielding material so that all of the non-detector surfaces, except for the portion of the collecting surface in optical communication with the photodetector, are protected from radiation. By shielding material we mean a material that is highly attenuating to radiation that is to be detected by the detector. Typically, a shielding material for protection from ionizing radiation such as gamma radiation includes lead and heavy metal alloys. Such materials are well known to those skilled in the art of designing radiation detectors and nucleonic instruments.
    [00026] When the scintillator is thin, scintillation light generated as a result of the interaction of a gamma photon with the scintillation material is likely to be reflected several times internally before it enters the photodetector. Since each reflection can be less than 100% efficient, the ability to multiple reflections provides multiple opportunities for light loss and thus a decrease in the detector's detection efficiency. It is therefore preferred to provide the non-detector surfaces with means to reflect light internally within the detector. Preferably, the non-detecting surfaces are covered with a super-reflective layer, capable of reflecting at least 95% of the light within the scintillator and more preferably at least 98% of that light.
    [00027] When the detector unit includes more than one detector, deployed in the form of a detector array, a preferred embodiment of the invention includes a block of shielding material (a "detector block") having openings extending into a block surface, each opening containing a detector, the detector surface being accessible to radiation from outside the block. A portion of the detector surface may be covered by shielding material for the purpose of delimiting the area of the detector surface or to mechanically retain the detector within the opening. The detector's non-sensing surfaces can optionally be included partially or completely within the opening and covered by the shielding material. The detector block includes means by which the scintillator collecting surface can be brought into contact with a photodetector or a light transmitter. Such a means can take the form of an open passage through which the scintillator extends so that the collecting surface is accessible to the photodetector or light transmitter.
    [00028] The accuracy of the detector is increased by providing a means of collimation to restrict the path along which radiation can travel to the detector surface. The collimation medium includes a collimator formed from a shielding material and arranged so that radiation traveling to the detector surface in selected directions can contact the detector surface while radiation traveling from unselected directions is excluded from the detector surface. In this way, only radiation traveling along selected paths from a radiation source to the detector can be detected. Collimation can be arranged so that radiation from one or more selected radiation sources is detected. Satisfactory collimation design can significantly reduce the detection of scattered photons, which are normally deflected from the path along which they were emitted by the source. Alternatively, collimation can be designed so that scattered photons and other secondary radiation are preferentially detected. In a preferred embodiment, the collimation means includes a block of shielding material having a channel, or preferably a plurality of channels extending. The collimator block includes a plurality of channels, each channel being formed by the block and corresponding in position to one of the detectors in said arrangement. Each channel is formed to define the radiation path that is to be detected by each scintillator. Each channel has an opening at the end proximal to the scintillator which is preferably mounted on top of the scintillator's detecting surface so that the detecting surface, or a portion thereof, is within the opening of the channel. The end of a channel distal to the scintillator is opened to allow radiation to enter the channel and travel to the scintillator. The opening is preferably on the plane of a tangent to a circle with the source as its origin. The area of the distal opening defines the maximum usable area through which radiation can pass to the detector surface. The channel walls are usually straight. The length of the channels is determined according to the requirements of the detector and the radiation energy emitted by the source. A longer channel reduces the detection of scattered or reflected radiation more than a shorter channel and thus the resolution of detection of a particular radiation path is higher. The length of the collimation channels can be determined by the qualified person according to the type of radiation that is to be collimated, according to known principles of physics. Generally to collimate radiation from a cesium source (which is a preferred source for use in the method and apparatus of the invention), a collimation depth of at least 50 mm should be used. A cobalt source requires more collimation and generally a depth of at least 75 - 80 mm would be used. Amerício emits less energetic gamma radiation and requires only about 20 mm of collimation depth. Amerício can be used in some applications, but it would not be suitable for use in sweeping steel pipelines, which is a preferred application. The depth d of the collimator channels is preferably in the range of 30 - 150 mm. More preferably 50 <d <150 e, for use with a satisfactory cesium source for sweeping large pipelines d is more preferably about 80 - 120 mm.
    [00029] The channel cross section can be any convenient shape, although it is preferred that the channel has the same shape and orientation as the detector surface. The channel often has a generally rectangular cross section. The shape and / or size of the channel cross section can change along the length of the channel, or they can remain substantially constant. In a preferred embodiment, at least one of the collimator channels has at least one wall defining the channel that is aligned with a radius of a circle having the source as its origin. Preferably, each channel wall is aligned with a different radius of the circle so that the channel opening is aligned to face directly towards the source.
    [00030] Preferably, in such an arrangement, the end of the collimator distal to the scintillator has an opening in the plane of a tangent to a circle having the source as its origin. In this way, the detection of photons traveling in a straight line from the source, through the target structure along the collimator channel to the detector can be maximized for any given detector surface area. More preferably, all collimator channels have at least one wall and preferably all of their walls are aligned with the radius of a circle having the source as their origin. In such an arrangement, the walls of the collimator channels are not parallel to each other and all channels face the direction of the source. When this collimator channel alignment is adopted, and the array of detector units is arranged in an arc having an origin that is not the source, at least some of the collimator channels do not extend in a direction that is perpendicular to a tangent to that bow. This is a preferred arrangement for sweeping a cylindrical structure such as a pipeline. In order to produce the collimator channels having this preferred alignment, it is preferred to form each channel in a block of shielding material by means of a machining method. For this reason, the use of shielding material plates, for example steel plates, of the type found in X-ray tomography detector units (for example as described in US-A-4338521) is not preferred.
    [00031] In one embodiment of the apparatus of the invention, the detector unit includes a collimator block and a detector block, joined together such that the proximal end of each channel is in register with the detector surface of a detector. The detector block and collimator block are joined together so that the connection between them does not allow radiation to collide on the detector surface of a detector that has not traveled through a channel registered with the detector surface. It may be possible to form the detector block and the collimator block from a single piece of shielding material, but it is usually easier to manufacture them separately and then join them together.
    [00032] The collimator block can be formed from a dense shielding material such as lead or heavy metal alloy that attenuates gamma radiation. Alternatively, the collimator block can be formed, at least in part, from a less dense material, such as steel, which provides less shielding, but which is not as heavy as the denser shielding materials such as lead or heavy metal alloy. In a version of such a collimator, collimator channels are formed from a first material, such as steel, and a layer of a second material, such as a heavy alloy, having a greater shielding capacity than the first material, is positioned over at least one outer surface of the detector unit. In this way, the detector unit can be better protected from the impact of scattered radiation from selected directions than from other directions. In practice, it is possible to determine, by calculation and / or modeling, the probability at which scattered gamma radiation from particular angles will collide in the detector unit. This information can then be used to provide more shielding on those detector unit surfaces to which scattered gamma photons are more likely to contact the detector units. More shielding can be provided either by using a denser material or by increasing the thickness of the shielding material. An advantage of providing different shielding to different parts of the detector unit, or forming the detector unit of different materials, is that the weight of the detector unit can be reduced while the shielding and collimation of the detectors is maintained substantially. An additional advantage of using a material such as steel to form at least part of the collimator is gained if the material has greater structural strength than a traditional dense shielding material such as lead or heavy alloy so that less structural support must be used to support the collimator block.
    [00033] The photodetector can be a photodiode, photomultiplier valve (PMT) or other suitable light detecting device. Currently, PMTs are preferred over photodiodes because they are more sensitive to very low light levels, although the use of other photodetectors, such as silicon photomultipliers or avalanche photodiodes may be preferable when technology is developed. The photodetector generates an electrical signal in response to light entering it through an optical window. The wavelengths detected by the photodetector should be matched as far as possible to the wavelengths generated by the scintillator to maximize detection efficiency. Usually a photodetector is provided for each scintillator so that the amount of radiation detected by each scintillator can be measured independently of the other scintillators.
    [00034] The photodetectors are retained in position by means of fixation such as a clamp or support. When more than one photodetector is present, they can be mounted in fixed positions within a mounting block. The mounting block is made of a material that is impervious to light and any other radiation that is likely to affect the signal produced by the photodetector. The photodetector is mounted with its optical window optically coupled to a scintillator collecting surface. The photodetector can be coupled using an optically coupling adhesive. Selection of a satisfactory optical coupling material such as an adhesive having some resilient elastic properties can provide the detector unit with some resistance to the effects of vibration or impact shock. Normally, the photodetector is adjacent to the scintillator, but it can be physically separated from the scintillator if a light transmitting means is provided to transmit light from the scintillator to the photodetector. In that case, it is important that the efficiency of light transmission is as high as possible.
    [00035] The photodetector can be in a coaxial relationship with its respective scintillator and collimator. Alternatively, the photodetector can be mounted at an angle to the axis of the collimator and scintillator, for example at an angle between about 45 and 100 ° to that axis, especially about 90 °. An advantage of mounting the photodetector at an angle to the scintillator and collimator axis is that the total depth of the detector unit can be reduced compared to a detector unit on which the photodetector is mounted coaxially.
    [00036] Reducing the depth of the detector unit helps to minimize the space needed around the target structure to perform a sweep and this can allow sweeping in restricted spaces and / or minimize the need to entrench an oil pipeline before sweeping.
    [00037] In a preferred embodiment of the invention, an array of n detector units is provided, including an array of n radiation detectors including: n scintillators, n photodetectors, each photodetector being optically coupled with a respective scintillator, a detector block Highly attenuating material is made incorporating a plurality of n channels extending through the detector block from a first surface to a second surface, each channel being sized to accommodate a single scintillator, and a collimator block including a block of shielding material having n channels extending through it, and where the collimator block is joined to the detector block so that each channel is registered with a scintillator, where each scintillator is located within a channel in the detector block, where n = an integer in the range of 2 - 150. Each detector surface preferably forms a tangent to an arc of a circle having a radiation source as its source. In one embodiment, each detector surface forms a tangent to the surface of part of a sphere having the source of radiation as its origin.
    [00038] The source unit includes a penetrating radiation source, a source holder and a collimator. Collimator and source holder can be combined. The collimator is formed from a material that is highly attenuating to the radiation emitted by the source and is normally formed from a heavy alloy material of the known type and generally used to shield radiation from the appropriate energy and type. The collimator is located and adapted to limit the radiation emitted by the source unit to a predetermined beam shape and direction. Preferably, the radiation beam is formed by the collimator to form a fan, cone or cone trunk, or sector in each case having the source as its source. A preferred beam shape is a cylindrical sector, that is, a sector having a thickness rather than being planar. Preferably, the beam is collimated to provide a beam area at the location of the detectors that has the same general shape and area as the combined detector surfaces of the detector array. In the preferred form of the apparatus, the source unit is mounted on a support, preferably in the region of one end of a long support.
    [00039] The radiation source is selected for the transparency to radiation of the materials to be measured, for example a container and / or its contents (that is, the attenuation coefficient of the medium) and the availability of satisfactory sources and detectors. For sweeping large solid structures such as process containers and pipelines, satisfactory sources of range include 60Co and 137Cs, 133Ba, 241 Am, 24Na and 182Ta, however any range-emitting isotope of sufficient penetrating power could be used, and many such are already commonly used in density meters, such as those used as level measurement devices. Typically, the half-life of the radioisotope used will be at least 2, and desirably at least 10 years. The half-lives of the radioisotopes mentioned above are: 137Cs range about 30 years, 133Ba about 10 years and 24Am about 430 years. Satisfactory sources generally emit radiation at energies between about 40 and 1500 keV.
    [00040] The source unit may include one or more than one source. The scanning method can use more than one source unit, if necessary.
    [00041] The device also includes a signal / data processor to operate on the electrical signal from the detectors in the detector units and a controller to control the operation of the device. Signals representative of the photon counts detected by the scintillators are processed by the data processor. The signal can be subjected to smoothing or stabilization algorithms, averaged or otherwise operated according to standard practices. A data processor can perform calculations based on the signal from the radiation detector or a signal processor, if present. The data processor can produce information regarding the amount of radiation measured over a period of time, or it can also calculate properties derived from the scanned structure, usually in the form of a volume density or a change in volume density between radiation paths across structure. The scanning method is performed at a plurality of positions shifted radially around the structure so that density data can be acquired at a variety of angles across the structure and a tomography algorithm can be used to provide information about changes in density at different paths through the structure. In a preferred form, the data from the detectors is operated by the data processing unit using tomography algorithms in order to produce a graphical representation of the density or composition of the structure along different paths. The data processor may contain calibration or information regarding the radiation source. The data processor output can be connected to a display or transmission medium (wirelessly optionally) so that a signal can be sent from the device to a remote location. Alternatively, a signal including data from the radiation detector itself can be sent, for processing to a remote location. A power source is provided to energize the photodetectors, data processor and control electronics and also to energize motors to move the device.
    [00042] In use in the scanning method of the invention, the apparatus is deployed so that the source unit and detector units are positioned in relation to the structure to be scanned so that one or more radiation paths from the source to detectors in the detector unit go through the desired portion of the structure. The amount of radiation, in the form of counts, is measured by the detector in each detector unit deployed on the device. The scanning method is performed at a plurality of positions displaced radially around the structure so that density data can be acquired at a variety of angles across the structure. The device can then be moved to a different location or orientation with respect to the structure and the measurement is repeated. In this way, a record of radiation attenuation for each radiation path through the structure can be gathered and used to calculate the location of changes or build a representation of the structure and its contents. Information such as changes in density that can highlight faults or other characteristics within the structure can be obtained from the data gathered from the detectors using data analysis tools known for use in tomography methods.
    [00043] For underwater operation, it is preferred to increase the flotation of the device by means of a flotation block. If used, the float block can be attached to the device by means of a flexible fixation so that the produced buoyancy force can be balanced during movement of the device. In addition or as an alternative, spaces within the apparatus may contain foam material to provide positive buoyancy to the apparatus. Parts of the apparatus may be covered with an elastic foam material, again for the purpose of providing buoyancy and also to protect the apparatus from physical damage, such as impact damage, and environmentally induced damage such as corrosion.
    [00044] The invention will be further described with reference to the accompanying drawings, which are: Figure 1: a schematic view of a scintillator suitable for use in the method and scanner of the invention. Figure 1 A: A view of the scintillator of Figure 1 from direction A. Figure 18: A schematic view of an alternative scintillator suitable for use in the method and scanner of the invention. Figure 19: a schematic view through a section of a detector unit. Figure 20: a schematic view through a longitudinal section of a detector unit. Figure 21: a schematic view of a detector block as part of a radiation detector according to the invention. Figure 22: a schematic view of a photomultiplier assembly block as part of a radiation detector according to the invention. Figure 23: a schematic view of a collimator block as part of a radiation detector according to the invention. Figure 5: a schematic section view of a radiation detector according to the invention. Figure 24: a schematic view through a section of an alternative detector unit. Figure 25: a front elevation view of the detector unit of Figure 7. Figure 26: a diagrammatic view of a preferred arrangement of the apparatus. Figure 27: a schematic view of an array of detector units for an apparatus according to the invention. Figure 28: a schematic view of part of an appliance according to the invention. Figure 29: a schematic elevation view of an apparatus according to the invention. Figure 30: a schematic perspective view of the apparatus shown in Figure 12. Figure 31: a schematic elevation view of an apparatus according to the invention, and Figure 32: a schematic elevation view of an apparatus according to the invention.
    [00045] Figures 1 and IA show a BGO 10 scintillation crystal having a thickness t of 5 mm, a height h of 30 mm and a depth d of 75 mm. The detecting surface 12 is opposite the collecting surface 14. All surfaces of the crystal except the detecting and collecting surfaces are covered with a highly reflective layer. Figure 1B shows an alternative scintillation crystal.
    [00046] Figure 2 shows a cross section through a detector unit 30, including a heavy alloy block 16 which is highly attenuating to radiation, of the type used as a shielding material for gamma radiation. The block has collimation channels 18 extending from the front face to the opposite rear face of the block. In use, a scintillator crystal 10 is housed in the block, with the crystal detecting surface on the front face of the block and the collecting surface 24 optically connected to PMT 20. PMT 20A is connected to an adjacent crystal 10 (not shown), and is shown to demonstrate the packaging of the PMTs within the detector unit. The detector unit includes nineteen detectors, each including a crystal 10 and a PMT 20 and mounted on record with a collimation channel 18 on the detector unit block.
    [00047] Figure 3 shows a longitudinal section through a mounted radiation detector including a collimator block 40, a detector block 20 and a PMT assembly block 30, each shown individually in Figures 4 - 6. The blocks are assembled together so that channels 46, 36 and 26 are all on record, together forming channels extending from the front face of the collimator block to the rear of the PMT assembly block. A scintillator 10 is housed within channel 26 and a PMT 50 is housed within channel 36. The PMT can be connected to an electronic data processing and control device via connectors accessible from the rear of channel 36. Channels 46a, 36a and 26a and scintillator 10a and PMT 50a are shown in dashed outline because they are not in the same plane as the respective channels and components in solid outline. In the shown embodiment, the longitudinal axes of the channels form an angle between 1 and 2 ° with the longitudinal axis 51 of each block 20, 30 and 40.
    [00048] Figure 4 shows a detector block that includes a rectangular heavy alloy block 21 that is highly attenuating to radiation, of the type used for as a shielding material for gamma radiation. The block has channels 26 extending from the front face 22 of the block to the opposite rear face 24. Blind receptacles 28 are provided for locating and assembling a collimator block. The channels 26 are sized to accommodate a scintillation crystal. In use, a scintillator crystal is housed in each channel 26, with the crystal detecting surface on the front face 26 of the block and the collecting surface on the rear face 24. Figure 5 shows a photomultiplier assembly block 30 that includes a rectangular block of white plastic material such as polytetrafluoroethane. Channels 36 extend from the front face 32 of the block to the opposite rear face 34. The channels are each of an appropriate size to accommodate a small photomultiplier valve. The channels are positioned in the block such that each opening in the front face of the block 30 contacts against the collecting surface 14 of a scintillation crystal mounted on an adjacent detector block when the rear face 24 of the detector block is placed against the face front 32 of the PMT mounting block. Blind receptacles 38 are provided for locating and mounting to the detector block. Figure 6 shows a collimator block including a heavy alloy rectangular block 40 that is highly attenuating to radiation, of the type used as a shielding material for gamma radiation. The block has channels 46 extending from the front face 42 of the block to the opposite rear face 44. Blind receptacles 48 are provided for locating and mounting a detector block. Channels 46 have a width and height that are slightly less than the width and height of the scintillator housing channels in the detector block. In a mounted radiation detector, the rear face 44 of collimator block 40 is mounted against the front face 22 of detector block 20 such that channels 46 are on record with channels 26. In Figure 10, a detector unit consisting of 19 collimator channels, scintillators and PMTs are shown, in which the collimator channels are formed in a single block being spaced apart and angled to each other by an angle of about 1 ° of arc.
    [00049] Figures 7 and 8 show an alternative arrangement for a detector unit. In Figure 7, block 60 forming collimator 62 and retaining scintillator 64 and PMT 66 is formed of stainless steel. The PMT is mounted out of alignment with the radiation direction in order to reduce the total depth of the detector unit. The radiation direction is indicated by the arrow. Figure 8 shows an elevation of the arrow direction. Layers 68 and 69 of a dense heavy alloy shielding material are positioned above and below the steel block 60. This material provides additional shielding for scattered radiation detectors colliding with the detector unit.
    [00050] Figure 11 shows a support 70 rigidly attached to one end to a generally curved formed detector housing 72, all formed of an aluminum alloy, and the other end to a source unit 74. A source arrangement and units of detector is shown in Figure 9. The direction of three collimator channels is illustrated in order to show that they align with the source direction and are not aligned with the Rt radius of the structure. The source housing and detector is arranged to rotate about a central point on the structure in a path having a radius Rt. The source unit includes a cesium source of gamma radiation 78 surrounded by heavy alloy shielding material 76 including an opening for collimating radiation in a fan-shaped beam 80 into the detector housing. The detector housing includes an aluminum alloy cage and, in the embodiment shown, contains two curved arrays of detector units 30, one at each end. The detector housing includes rails along which the detector units can be moved to different locations within the housing. The housing shown could accommodate one or more arrangements of additional detector units, if necessary.
    [00051] Figures 12 and 13 show an apparatus for sweeping steel tube 82, having an internal diameter of about 234 mm and a wall thickness of about 43 mm, to detect changes and flaws in the wall. The tube wall is surrounded by a layer of insulating material 84. A support member 86 is fastened to the pipeline by means of clamps 88 hydraulically operated through arms 90. The support member also supports rails 92, which support the support 70, detector housing 72 and source unit 74. A motor 94 mounted on the detector housing is operable to move the detector housing and source unit along the tracks and thereby rotate the position of the source and detectors around the pipeline. At each position, radiation emitted by the source for each detector in the two detector units forms several radiation paths through the pipe wall and isolation equal to the number of detectors, which in this case is (19 x 2) = 38 separate paths that can be scanned at the same time. When the device is rotated to a different position along the tracks, additional paths 38 can be swept. Data in the form of counts detected by the detectors are processed and stored by a data processor housed in housing 96 located at the top of the support. Deployment of the detector units in the positions shown is particularly satisfactory for scanning the pipeline and insulation walls to detect flaws and changes between different locations on the pipe.
    [00052] In the detector housing shown, there is space for one or more detector units to be placed in the central portion of the housing. In this position, a detector unit would detect radiation that passed through the lumen of the tube and its contents. Use of a detector unit in such a position would therefore be satisfactory to conduct tomography scans of the tube and contents.
    [00053] Figures 14-15 show another embodiment of a scanner according to the invention. The apparatus includes two parts of an articulated housing 102 that together form a clamp with jaws that can be opened (Figure 14) and closed (Figure 15) around tube 82 by operating a hydraulic cylinder 98. When closed, the articulated housings surround the tube, but are spaced apart from the surface of the tube. Rollers 100 contact the surface of the tube and maintain the spacing of the tube housing. Housing 102 covers and contains a detector housing for one or more arrays of detector units and a source unit as described above. The source and detector unit are mounted in a fixed relationship with each other and are arranged to move along a track within the jaws to rotate around the circumference of the pipeline. Adjustable claws 104 are present on either side of the tube which are operable by means of a hydraulic cylinder 108 to grasp the tube and center it within the space between the jaws and the tube. When the hinged housing is closed around the tube and centered via claws 104, the source unit and detector housing are rotated around the tube so that density information can be acquired by the detectors at a plurality of angular locations around the tube. The data is then processed to produce a tomography image or an indication of one or more properties of the pipeline at different locations around the sweep operation path. When sufficient data has been acquired, the housing is opened and moved to a different location along the pipeline for new scanning data to be acquired.
    权利要求:
    Claims (23)
    [0001]
    1. Method for scanning a subsea pipeline (82) to detect changes in density between different parts of the subsea pipeline (82) or to deduce information about the contents of the subsea pipeline (82), characterized by the fact of understanding the steps of: providing at least one source of gamma radiation (74), and a plurality of detector units (30) capable of detecting gamma radiation, each detector unit (30) including: i. a radiation detector (72) including a scintillator (10) including a sparkling material and having a detector surface (12) defined by its thickness t and height h, where t <h on the detector surface (12) and having a depth d perpendicular at the detector surface (12) of at least 2t, ii. a photodetector (20) to detect the light emitted by the scintillator (10) in response to gamma radiation, and iii. a collimator (16,18) placed between the scintillator (10) and the radiation source; iv. er the source unit (74) emits gamma radiation along a predetermined radiation path to the detector, where the path passes through at least a portion of the underwater pipeline (82); v. tell the number of gamma radiation photons detected by each of the detectors; calculate a density value for each photon measurement path detected by the detector associated with the respective path; and repeat the measurements in a plurality of positions displaced radially around the undersea pipeline (82), so that density data is acquired at a variety of angles through the undersea pipeline (82) and a tomography algorithm is used to provide information on changes in density on different paths through the underwater pipeline (82).
    [0002]
    2. Method according to claim 1, characterized by the fact that the plurality of detector units (30) are arranged in close proximity to each other in the form of an arc having a radius centered in the center of the underwater pipeline (82) to be scanned .
    [0003]
    Method according to either of claims 1 or 2, characterized by the fact that the source unit (74) and the detector units (30) are mounted separately spaced on a support (70) that provides means for at least one portion of the underwater pipeline (82) to be scanned is located between the source unit (74) and the detector units (30).
    [0004]
    Method according to any one of claims 1 to 3, characterized by the fact that the source unit (74) and the detector units (30) are rotated around the subsea pipeline (82), the radius of rotation having a origin within the submarine pipeline (82).
    [0005]
    5. Method according to claim 4, characterized by the fact that a guide means is provided to guide the rotation in a predetermined path.
    [0006]
    6. Method according to claim 5, characterized by the fact that the guide medium is indexed.
    [0007]
    Method according to any one of claims 1 to 6, characterized by the fact that 1 mm <t <5 mm, 10 mm <h <50 mm and 25 mm <d <75 mm.
    [0008]
    Method according to any one of claims 1 to 7, characterized by the fact that the collimator depth (16,18) of each detector unit (30) is in the range of 50 - 150 mm.
    [0009]
    9. Method according to any one of claims 1 to 8, characterized by the fact that the end of the collimator (16,18) distal to the scintillator (10) has an opening in the plane of a tangent to a circle having the source as your origin.
    [0010]
    10. Method according to any one of claims 1 to 9, characterized by the fact that at least one of the collimators (16,18) has at least one wall defining a channel (18) that is aligned with a radius of a circle having the source as its origin.
    [0011]
    11. Method according to claim 10, characterized by the fact that each channel wall (18) is aligned with a different radius of the circle and the channel opening is aligned to face directly to the source.
    [0012]
    A method according to any one of claims 1 to all, characterized by the fact that the photodetector (20) is mounted at an angle to the axis of the collimator (16,18) and the scintillator (10).
    [0013]
    13. Apparatus for sweeping an underwater pipeline (82) to detect changes in density between different parts of the underwater pipeline (82), characterized by the fact that it comprises: at least source unit (74) including a gamma radiation source (74) and a shielding material arranged to restrict the emission of gamma radiation from the source unit (74); a plurality of detector units (30) capable of detecting gamma radiation, each detector unit (30), comprising: i. a radiation detector (72) including a scintillator (10) including a sparkling material and having a detector surface (12) defined by its thickness t and height h, where t <h on the detector surface (12) and having a depth d perpendicular at the detector surface (12) at least 2t, ii. a photodetector (20) to detect the light emitted by the scintillator (10) in response to gamma radiation, and iii. a collimator (16,18) placed between the scintillator (10) and the radiation source; and a data processing means for calculating a density value for each photon measurement path detected by the detector associated with the respective path; wherein the apparatus is configured to take density measurements in a plurality of positions displaced radially around the subsea pipeline (82), so that density data is acquired at a variety of angles via the subsea pipeline (82) and a tomography algorithm is used to provide information about changes in density on different paths through the underwater pipeline (82).
    [0014]
    Apparatus according to claim 13, characterized in that the source unit (74) and the detector units (30) are mounted on a support (70) in a spaced relation to the fixed part having a means to rotate the source unit (74) and the detector units (30) around an arc having an origin located between the source unit (74) and the detector units (30).
    [0015]
    Apparatus according to claim 14, characterized in that the means for turning includes a guide means for guiding the rotation in a predetermined path.
    [0016]
    An apparatus according to claim 15, characterized in that the guide means includes more than one portion which is movable to form a continuous guide means.
    [0017]
    Apparatus according to any one of claims 13 to 16, characterized in that the collimator (16,18) is formed, at least in part, from a first material (60) having a first shielding capacity for gamma radiation , and a layer of a second material (68, 69), having a greater shielding capacity than the first material (60), which is positioned on at least one external surface of the detector unit (30).
    [0018]
    Apparatus according to any one of claims 13 to 17, characterized in that the plurality of detector units (30) is arranged in close proximity to one another in the form of an arc having an origin located between the source unit ( 74) and the detector units (30).
    [0019]
    19. Apparatus according to any of claims 13 to 18, characterized by the fact that 1 mm <t <5 mm, 10 mm <h <50 mm and 25 mm <d <75 mm and the collimator depth (16,18) of each detector unit (30) is in the range of 50 - 150 mm.
    [0020]
    Apparatus according to any one of claims 13 to 19, characterized in that the end of the collimator (16,18) distal to the scintillator (10) has an opening that is on the plane of a tangent to a circle having the source as its origin.
    [0021]
    21. Apparatus according to any one of claims 13 to 20, characterized by the fact that at least one of the collimators (16,18) has at least one wall defining a channel (18) which is aligned with a radius of a circle having the source as its origin.
    [0022]
    22. Apparatus according to claim 21, characterized by the fact that each of the channel walls (18) is aligned with a different radius of the circle and the channel opening is aligned to face directly towards the source.
    [0023]
    23. Apparatus according to any of claims 13 to 22, characterized in that the photodetector (20) is mounted at an angle to the axis of the collimator (16,18) and scintillator (10).
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    同族专利:
    公开号 | 公开日
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    GB2526471A|2015-11-25|
    GB201515013D0|2015-10-07|
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    US20180011208A1|2018-01-11|
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    JP2015501435A|2015-01-15|
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    EP2773950B1|2020-02-12|
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    EA201490918A1|2014-10-30|
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    WO2013064838A9|2013-12-05|
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    AU2012330895B2|2016-03-10|
    KR20140084310A|2014-07-04|
    EP2773950A1|2014-09-10|
    AU2016203850A1|2016-06-30|
    WO2013064838A1|2013-05-10|
    GB2526470A|2015-11-25|
    AU2012330895A1|2014-06-19|
    GB2496736A|2013-05-22|
    AU2016203850B2|2017-06-08|
    EP3650845A1|2020-05-13|
    US20150241572A1|2015-08-27|
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    法律状态:
    2019-08-27| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|
    2019-11-12| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2020-04-22| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2020-09-15| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 02/11/2012, OBSERVADAS AS CONDICOES LEGAIS. |
    2021-10-05| B15K| Others concerning applications: alteration of classification|Free format text: RECLASSIFICACAO AUTOMATICA - A CLASSIFICACAO ANTERIOR ERA: G01N 23/04, G01T 1/164 Ipc: G01N 23/095 (2018.01) |
    优先权:
    申请号 | 申请日 | 专利标题
    GBGB1118944.6A|GB201118944D0|2011-11-02|2011-11-02|Scanning method and apparatus|
    GB1118944.6|2011-11-02|
    GB201118943A|GB201118943D0|2011-11-02|2011-11-02|Radiation detector|
    GB1118943.8|2011-11-02|
    GBGB1200744.9A|GB201200744D0|2012-01-17|2012-01-17|Scanning method and apparatus|
    GB1200744.9|2012-01-17|
    US201261597272P| true| 2012-02-10|2012-02-10|
    US201261597237P| true| 2012-02-10|2012-02-10|
    US201261597354P| true| 2012-02-10|2012-02-10|
    US61/597354|2012-02-10|
    US61/597272|2012-02-10|
    US61/597237|2012-02-10|
    PCT/GB2012/052737|WO2013064838A1|2011-11-02|2012-11-02|Scanning method and apparatus|
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