X-ray imaging apparatus and method for extending image parameters

Abstract

The present invention provides a computed tomography scanner, a computer program, and a computer-readable storage medium that can be used to broaden the field of view for a specific angle. [Solution] A step of performing a projection image scanning sequence (PSS) by using an imaging focus pattern to generate multiple projection images, wherein the imaging focus pattern includes multiple X-ray focal positions on at least one target (144) such that the volume of the object (134) to be reconstructed is irradiated by X-ray emission cones (132) of different volumes; a step of performing a tomography scanning sequence (TSS) by performing the projection image scanning sequence (PSS) at different field angles; and a step of performing an image reconstruction algorithm using the projection images to reconstruct a 3D image of the object (134).

Description

Technical Field

[0001] The present invention relates to a method for operating a computed tomography apparatus, a computed tomography apparatus, a computer program, and a computer-readable storage medium.

[0002] Specifically, the present invention can be used for imaging living or inanimate objects. Specifically, the present invention can propose a method for expanding the field of view by using a focus position pattern. Specifically, the focus position pattern can be selected with respect to the spatial spread of an object in all dimensions. However, other application fields of the present invention are also feasible.

Background Art

[0003] In the field of X-ray imaging, the design of X-ray sources typically plays an important role, and thus, the design of X-ray sources has been dramatically improved over the years. The main developments have focused on, for example, an increase in high voltage, an improvement in target power and focus size, and stability resulting in multiple different X-ray source concepts. One way to distinguish different X-ray source types can be a classification of X-ray sources based on focus size. There does not seem to be a strict definition that clearly distinguishes different X-ray source types. However, in the art, X-ray source types of macro focus and micro focus are recognized, where the focus sizes are in the millimeter and sub-millimeter ranges, respectively. Typically, a macro focus X-ray source can be a sealed vacuum X-ray source. Macro focus sources typically cover a range of focus sizes from 0.1 mm down to 1 μm. These X-ray sources are typically open-type X-ray sources that create a vacuum during operation and include an X-ray optical system that compresses and shapes an electron beam inside the electron gun of the X-ray source. Today, so-called nanofocus X-ray sources that create a focus in the sub-micron range down to 100 - 200 nm are also available. To reach such small foci, it is necessary to fully control the electron beam, focusing unit, and target design. Recent developments also make available features that define the focus position on the target.

[0004] U.S. Patent Application Publication No. 2021 / 410260 discloses an X-ray source comprising an electron source, tuning means for adjusting the orientation of an electron beam generated by the electron source, focusing means configured to focus the electron beam according to a focus setting, a beam orientation sensor arranged to generate a signal indicating the orientation of the electron beam relative to a target position, and a controller operably connected to the focusing means, the beam orientation sensor, and the tuning means. Also disclosed is an X-ray source comprising a target orientation sensor and a target adjustment means, wherein the controller is configured to cause the beam adjustment means and / or the target adjustment means to adjust the relative orientation between the electron beam and the target.

[0005] European Patent Application Publication No. 3240011 discloses a technique for electronically aligning the central beam of an X-ray tube to a radiation detector. In one example, the X-ray system includes an X-ray tube and a tube control unit (TCU). The X-ray tube includes a cathode including an electron emitter configured to emit an electron beam, an anode configured to receive the electron beam and to produce an X-ray having a central beam from electrons of the electron beam colliding with the focal point of the anode, and a steering magnetic multipole between the cathode and the anode configured to generate a steering magnetic field from a steering signal. At least two poles of the steering magnetic multipole are on the opposite side of the electron beam. The TCU includes at least one steering driver configured to generate a steering signal. The TCU is configured to convert an offset value into a steering signal.

[0006] European Patent No. 3764325 discloses a system according to an embodiment including a circuit. The circuit inputs third projection data into a first trained model to generate fourth projection data, receives third projection data obtained from a CT (computed tomography) scan, and reconstructs a first image based on the fourth projection data. The first trained model is trained using first projection data as input and second projection data or first subtraction data between the second and first projection data as output, wherein the first projection data is acquired using an X-ray source having a first focal size, the second projection data is acquired using an X-ray source having a second focal size smaller than the first focal size, and the third projection data is acquired using an X-ray source having a third focal size larger than the second focal size.

[0007] U.S. Patent No. 1,1331,055 discloses a computed tomography apparatus and method for influencing the position of a focal point in an X-ray emission source having a centering device that positions an electron beam and a focal point. The method includes the steps of positioning a reference object in the beampath of X-ray emission between an X-ray emission source and an X-ray emission detector, wherein the X-ray emission detector has a detection element for generating an X-ray image; capturing an X-ray image of the reference object at different powers; reducing the focal displacement resulting from different powers based on a comparison of the X-ray images captured at different powers by setting at least one modified current to operate one or more centering devices of the X-ray emission source; and operating a computed tomography apparatus with the modified currents that reduce the focal displacement.

[0008] International Publication No. 2012 / 123843 discloses an X-ray tube for stereoscopic imaging, an X-ray imaging system for stereoscopic imaging, a method for stereoscopic imaging, and computer program elements and computer-readable media for stereoscopic imaging. To provide stereoscopic imaging with improved space requirements and enhanced gravimetric characteristics, an X-ray tube is provided, comprising a cathode, an anode, means for deflecting the electron beam, an X-ray aperture having at least a first hole and a second hole, and an envelope housing the cathode and anode. The deflection means are adapted to deflect the electron beam from the cathode so that the electron beam strikes the anode at at least two stereofocal positions separated from each other by a first distance defining the stereoscopic direction. The aperture is fixedly positioned inside the envelope, and an X-ray beam is generated at each focal point and emitted in the line of sight direction through at least one of the first and second holes in the aperture. The direction of the first distance is perpendicular to the line of sight, and the first distance is adaptable. [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] Therefore, an object of the present invention is to provide a method for operating a computed tomography apparatus, a computed tomography apparatus, a computer program, and a computer-readable storage medium that at least partially overcome the aforementioned problems of the prior art.

[0010] In particular, the objective of the present invention is to expand the field of view of a computed tomography (CT) scanner. [Means for solving the problem]

[0011] This problem is addressed by a method for operating a computed tomography apparatus, and a computed tomography apparatus, a computer program for operating the computed tomography apparatus in a way that widens the field of view, and a computer-readable storage medium, as described in the features of the independent claims. Advantageous embodiments that can be realized in separate ways or in any combination are enumerated throughout this specification in addition to the dependent claims.

[0012] A first aspect discloses a method for operating a computed tomography apparatus. Any definitions, embodiments, and / or further aspects disclosed elsewhere in this specification may be referenced in relation to this aspect.

[0013] A method for operating a computed tomography scanner includes the following steps, which may be performed in a given order. However, a different order may also be possible. Furthermore, two or more steps of the method may be performed simultaneously. Thereafter, the steps of the method may overlap at least partially in time. Furthermore, the steps of the method may be performed once or repeatedly. Thus, one or more or all of the steps of the method may be performed once or repeatedly. The method may include additional steps of the method not enumerated herein.

[0014] A computed tomography (CT) scanner comprises at least one X-ray source configured to generate an X-ray emission cone for illuminating an object. Furthermore, the computed tomography scanner comprises at least one detector configured to detect the X-ray emission of the X-ray emission cone that has interacted with the object. The X-ray emission source comprises at least one electron-optical device configured to variably position at least one electron beam over multiple focal positions on at least one target contained within the X-ray emission source, in such a manner that multiple different X-ray emission cones emerging from a focal point are generated for imaging different parts of the object.

[0015] The term “computed tomography apparatus” as used herein is a broad term, given to those skilled in the art in a normal and customary sense, and is not limited to any special or customized meaning. Specifically, the term may refer, without limitation, to an apparatus configured to perform imaging techniques for non-destructively obtaining three-dimensional images of the internal structure of an object. A computed tomography (CT) apparatus may be a microcomputed tomography apparatus configured to image an object with micron-level resolution or submicron-level spatial resolution. The object may be inanimate or living, such as an animal.

[0016] The term “X-ray emission source” as used herein is a broad term, given to those skilled in the art in a normal and customary sense, and not limited to any special or customized meaning. Specifically, the term may refer, without limitation, to any device configured to emit X-ray radiation. Specifically, an X-ray tube may comprise a cathode and a target, also called an anode. More specifically, the cathode may be the negative electrode and the target may be the positive electrode. The cathode may be configured to emit electrons, which may be accelerated to the target using a high voltage potential. The emitted electrons may also be called an electron beam. X-ray radiation is produced via bremsstrahlung by the electrons striking the target at a specific location. The point where the electrons strike the target may also be called the focal point.

[0017] The term “X-ray emission cone” as used herein is a broad term, given to those skilled in the art in a normal and customary sense, and is not limited to any special or customized meaning. Specifically, the term may refer to, without limitation, multiple X-ray beams, which together form a cone. The cone may be a three-dimensional geometric structure defined by a base, such as a rectangle, circle, or ellipse. Further base shapes are also possible. Specifically, the tip or apex of the cone may emerge from the focal point of the X-ray emission source. The cone may extend in a direction toward the detector from the tip or apex. The shape of the X-ray emission cone may be formed by using one or more collimators. Specifically, the collimators may be configured to absorb X-ray emission. The X-ray emission cone may be configured in a way that irradiates at least a portion of an object, preferably in a way that the X-ray emission defining the X-ray emission cone interacts at least partially with the object.

[0018] The term “electron-optical apparatus” as used herein is a broad term, given to those skilled in the art in a normal and customary sense, and not limited to any special or customized sense. Specifically, the term may refer, without limitation, to any apparatus configured to adjust the direction and / or shape of an electron beam. Specifically, an electron-optical apparatus may be configured to adjust the direction of an electron beam in an X-ray source so that the position of the focal point on a target is adjusted. An electron-optical apparatus may be configured to variably adjust the direction of an electron beam in an X-ray source so that the position of the focal point on a target is variably adjusted. Specifically, the apparatus may be or comprise at least one magnet configured to adjust the direction of an electron beam. More specifically, the apparatus may be or comprise at least one coil and / or deflector having a controllable variable magnetic field strength configured to variably adjust the direction of an electron beam.

[0019] The term “focal position” as used herein is a broad term, given to those skilled in the art in a normal and customary sense, and is not limited to any special or customized meaning. Specifically, the term may refer, without limitation, to a particular position of the focal point on a target. Different focal positions may produce different X-ray emission cones. The focal position may vary depending on the field of view.

[0020] The term “detection,” as used herein, or its grammatical variations thereof, is a broad term, given to those skilled in the art, and is not limited to any special or customized meaning. Specifically, the term may refer, without limitation, to a quantitative and / or qualitative determination relating to at least one property of an object, such as at least one of physical, chemical, and biological properties, specifically a property such as the intensity of X-ray emission or a number of photons. The term “detector,” as used herein, is a broad term, given to those skilled in the art, and is not limited to any special or customized meaning. Specifically, the term may refer, without limitation, to a device configured to detect at least one particular physical or chemical property. Specifically, a detector may be configured to detect electromagnetic radiation. More specifically, a detector may be configured to detect the intensity of incident X-rays or a single X-ray photon. A detector may detect at least a portion of the X-ray radiation that interacts with an object. Specifically, a detector may detect the intensity of X-ray radiation that interacts with an object. A detector may be a planar detector or a curved detector. The detector may be positioned in a manner that detects X-ray radiation originating from the X-ray focal point.

[0021] The term “imaging” as used herein, or its grammatical variations thereof, is a broad term and is given a meaning that is common and customary to those skilled in the art, and is not limited to any special or customized meaning. Specifically, the term may refer, without limitation, to the process of generating an image of an object by performing measurements. The image may be reconstructed from measurement data generated during the measurement. The measurement may be performed to detect at least one characteristic of the object. Specifically, the term imaging may relate to irradiating an object with X-ray radiation, measuring the intensity of the incident X-rays, and using this data to reconstruct an image of the object, preferably a 3D image of the object.

[0022] This method is A step of performing a projection image scanning sequence (PSS) by using an imaging focus pattern to generate multiple projection images, wherein the imaging focus pattern includes multiple X-ray focal positions on at least one target such that the volume of the object to be reconstructed is irradiated by X-ray emission cones of different volumes; The process involves performing a tomographic scanning sequence (TSS) by performing a projection image scanning sequence (PSS) at different field of view angles, The process includes the step of performing an image reconstruction algorithm using a projected image to reconstruct a 3D image of an object.

[0023] As already described, the method includes the step of performing a projection image scanning sequence (PSS) by using an imaging focus pattern to generate a plurality of projection images, the step of including a plurality of X-ray focal positions on at least one target such that the imaging focus pattern includes a plurality of X-ray focal positions on at least one target so that the volume of the object to be reconstructed is irradiated by X-ray emission cones of different volumes.

[0024] The term "projected image" as used herein is a broad term and is given its ordinary and customary meaning to those skilled in the art and is not limited to a special or customized meaning. Specifically and without limitation, the term can refer to measurement data received by a detector. To generate a projected image, the measurement data can be processed by performing, for example, a logarithmic transformation of the measurement data or normalization against a measurement without an object. Projected images can be recorded for known focal positions and known field angles.

[0025] The term "projected image scanning sequence (PSS)" as used herein is a broad term and is given its ordinary and customary meaning to those skilled in the art and is not limited to a special or customized meaning. Specifically and without limitation, the term can refer to a sequence of multiple measurements of an object to generate measurement data. The measurement data can preferably include a plurality of projected images recorded for different focal positions. Specifically, the PSS can refer to a sequence of measurements at one particular field angle, whereby different focal positions are used in a way that multiple projected images are recorded for each measurement.

[0026] In a projected image scanning sequence, projected images can be recorded for a particular field angle. The different X-ray emission cones used to record the projections may not overlap sufficiently within the object. As a result, the different X-ray emission cones used to record the projections can be at least partially separated within the object. The projected images that can be recorded thereby will consequently show different parts of the object.

[0027] As used herein, the term "focus pattern" is a broad term that gives the ordinary and customary meaning to those skilled in the art and is not limited to a special meaning or a customized meaning. Specifically, without limitation, the term may refer to a specific arrangement of at least two focal positions for one specific viewing angle. By adjusting the focal positions as defined by the focus pattern, different X-ray emission cones can be generated. Different X-ray emission cones can irradiate different parts of the volume of the object to be reconstructed. Thereby, different projection images can be generated. The "volume of the object to be reconstructed" may refer to the selected part of the object for which the above projection images are generated.

[0028] In other words, during a projection image scanning sequence (PSS), a plurality of projection images can be recorded for one specific viewing angle. The plurality of projection images can be recorded for different focal positions. Thereby, the plurality of projection images can show different parts of the object.

[0029] As already shown, the method includes performing a tomographic scanning sequence (TSS) by performing a projection image scanning sequence (PSS) at different viewing angles.

[0030] As used herein, the term "tomographic scanning sequence (TSS)" is a broad term that gives the ordinary and customary meaning to those skilled in the art and is not limited to a special meaning or a customized meaning. Specifically, without limitation, the term may refer to a sequence of multiple measurements of an object for generating measurement data. The measurement data may include some plurality of projection images recorded for different viewing angles. The viewing angles at which the projection images are recorded may vary depending on the TSS procedure. In a specific TSS procedure, a single projection image can be recorded. In this case, the viewing angle remains constant. In the above TSS procedure, 3D information about the object may not be generated. In a more specific TSS procedure, by allowing the viewing angle to rotate 360°, it becomes possible to capture complete 3D information from all viewpoints around the object.

[0031] During TSS, multiple projection images of an object may be acquired. The projection images of the object may be captured over a field of view range exceeding 0°, preferably 180° or more, and more preferably 360° or more. To achieve this, the object or X-ray source may rotate together with the detector, either continuously or in small increments. During TSS and PSS, the relative position between the X-ray source and the detector may preferably remain fixed. During TSS and PSS, the detector and X-ray source may preferably be in a fixed position on the gantry and preferably not movable laterally.

[0032] The term “field of view” as used herein is a broad term, given to those skilled in the art in a normal and customary sense, and is not limited to any special or customized meaning. Specifically, the term may refer, without limitation, to the orientation or rotational alignment of the detector relative to the object being imaged. A particular field of view may refer to a specific angular position of the X-ray source relative to the object. To adjust the field of view, the X-ray source and detector may rotate together around the object. The orientation and / or position of the object may be maintained during such rotation. Alternatively, or additionally, the object may be rotated while the X-ray source and detector remain in place.

[0033] Specifically, TSS may refer to a sequence of measurements performed at different field angles. More specifically, TSS may refer to a sequence of measurements in which at least one PSS is performed at each particular field angle. Focus patterns may include a plurality of known specific arrangements of at least two focal positions for each particular field angle.

[0034] During a tomographic scanning sequence (TSS), several projection images may be recorded for different specific field angles. These multiple projection images can then show projections of the volume of the object being reconstructed from different field angles.

[0035] As already shown, the method includes the step of using a projected image to perform an image reconstruction algorithm in order to reconstruct a 3D image of an object.

[0036] As used herein, the term “reconstruction” is a broad term, given to those skilled in the art in a conventional and customary sense, and is not limited to any special or customized meaning. Specifically, the term may refer, without limitation, to the process of calculating an image by evaluating measurement data.

[0037] The step of determining a 3D image of an object by using an image reconstruction algorithm may include the steps of evaluating each captured projection image and, for each projection image, using the X-ray focal position on at least one target from which each projection image was captured. Alternatively or additionally, the method may further include the step of determining a 3D image of an object by using an image reconstruction algorithm, by evaluating each captured projection image and, for each projection image, using the field of view from which each projection image was captured. In other words, to generate a 3D image, multiple projection images may be evaluated, preferably by using an image reconstruction algorithm, and in particular by using known focal positions and known field of view from which a particular projection image among multiple projection images is recorded.

[0038] Specifically, the term "reconstruction" may include the use of a reconstruction algorithm configured to determine an image from measurement data. The term "image reconstruction algorithm" as used herein is a broad term, given to those skilled in the art in a conventional sense, and is not limited to any special or customized meaning. Specifically, the term may refer, without limitation, to a defined procedure for reconstructing an image, specifically a 3D image, by evaluating recorded measurement data.

[0039] An image reconstruction algorithm may be at least one iterative reconstruction algorithm, or may include at least one iterative reconstruction algorithm. The term “image reconstruction algorithm” as used herein is a broad term and is given the usual and customary meaning to those skilled in the art, and is not limited to any special or customized meaning. Specifically, the term may refer, without limitation, to a computational method used to progressively improve an estimate of a solution. An iterative reconstruction algorithm may repeatedly adjust the solution by applying a set of rules or modifications based on a comparison of the current estimate with the observed data or constraints.

[0040] Furthermore, the image reconstruction algorithm may be at least one analytical reconstruction algorithm, or may include at least one analytical reconstruction algorithm. The term “analytical reconstruction algorithm” as used herein is a broad term and is given the usual and customary meaning to those skilled in the art, and is not limited to any special or customized meaning. Specifically, the term may refer, without limitation, to a computational method used to determine a solution by applying one or more rules. An analytical reconstruction algorithm may be used to directly derive a solution by using one or more rules.

[0041] The analysis and reconstruction algorithm may be or may include a Feldkamp (FDK) type algorithm. During backprojection, the contribution of each projected image recorded at a given focal position to a given image pixel may be weighted by a coefficient that changes inversely proportional to the contribution of the X-ray emission cone corresponding to that pixel. The sum of the weights of different X-ray emission cones for a given pixel may be 1.

[0042] The process of performing a tomographic scanning sequence (TSS) by performing a projection image scanning sequence (PSS) at different field of view angles is as follows: This procedure can be repeated by rotating the X-ray source-detector-assembly relative to the object to generate a projection image for a specific focal position included in the imaging focus pattern, and performing at least one more rotation until a projection image is recorded for each specific focal position included in the imaging focus pattern, or This can be done by performing a sub-rotation of the X-ray source-detector-assembly relative to the object to generate a projection image for each specific focal position included in the imaging focus, and repeating this procedure by performing at least one further sub-rotation until a projection image is recorded for each sub-rotation included in the imaging focus pattern. The rotation can be associated with a field of view exceeding 0°, preferably 180° or more, and more preferably 360° or more.

[0043] The term “3D image” as used herein is a broad term, given to those skilled in the art in its ordinary and customary meaning, and is not limited to any special or customized meaning. Specifically, the term may, without limitation, refer to an image resulting from the reconstruction of measurement data extended into three dimensions. More specifically, a 3D image refers to a three-dimensional representation of the volume of an object being reconstructed, typically generated by evaluating a projected image.

[0044] The imaging focus pattern may be variable in such a way that the X-ray focal position on at least one target is variable. The term “variable” as used herein is a broad term and is given a meaning that is common and customary to those skilled in the art, and is not limited to any special or customized meaning. Specifically, the term may refer to the possibility of changing or altering a value that can be modified, without limitation. The X-ray focal position may be variable so that the generated X-ray cone can illuminate a variable portion of the volume of the object being reconstructed.

[0045] The method may further include the step of determining a variable X-ray focal position on at least one target by using a known 3D spatial extent of an object, thereby approximating the known 3D spatial extent by using a bounding box surrounding the object. The variable X-ray focal position may be determined in order to expand the field of view of the detector to cover the entire volume of the object to be reconstructed. The X-ray focal position may be determined so that the entire volume of the object to be reconstructed is fully exposed by the X-ray emission cone appearing at each field of view angle.

[0046] The term “3D spatial extent of an object” as used herein is a broad term, given to those skilled in the art in a normal and customary sense, and not limited to any special or customized sense. Specifically, the term may refer, without limitation, to the dimensions of at least a portion of the volume of the object being reconstructed in all three spatial coordinates. The known 3D spatial extent of an object may be evaluated to select a specific X-ray focal position in such a way that the generated X-ray emission irradiates the volume of the object being reconstructed, so that a corresponding projection image can be recorded. Thereafter, the field of view of the detector is adjusted in such a way that the volume of the object being reconstructed is imaged. The term “field of view” as used herein is a broad term, given to those skilled in the art in a normal and customary sense, and not limited to any special or customized sense. Specifically, the term may refer, without limitation, to the spatial extent of an object that is exposed to X-rays, contained within the X-ray emission cone, and captured by the detector.

[0047] To reconstruct a 3D image of an object, the volume of the object to be reconstructed may need to be contained within the detector's field of view. However, the 3D spatial extent of the object can broaden the detector's field of view for a particular focal position and corresponding X-ray emission cone. Therefore, changing the focal position can broaden the field of view so that the entire volume of the object to be reconstructed is captured, preferably at a particular field of view angle.

[0048] The term “bounding box” as used herein is a broad term, given to those skilled in the art in a normal and customary sense, and is not limited to any special or customized meaning. Specifically, the term may refer, without limitation, to a geometric frame that encapsulates at least a portion of an object in a manner that approximates the object’s three-dimensional spatial extent. The three-dimensional spatial extent of an object may, in particular, be approximated by the volume of the object and / or the entire object being reproduced. Specifically, a bounding box may approximate the geometric shape of an object by using a simpler geometric shape. More specifically, the coordinates of the bounding box that define the geometry of the bounding box may be chosen such that at least a portion of the object lies within the bounding box.

[0049] This method is The process of carrying out scouting procedures, A process of receiving user input related to the known 3D spatial extent of an object. A step of determining the known 3D spatial extent of an object by at least one of the steps of receiving data related to the 3D spatial extent of an object, wherein the data related to the 3D spatial extent of an object is Data of object models, such as CAD models of objects. The process further includes selecting from at least one of existing 3D tomography data or data representing the 3D volume of an object, such as volumetric data.

[0050] The known 3D spatial extent of the determined object may be the approximate 3D spatial extent of the object. In particular, the approximate 3D spatial extent of the object may include at least one simplified geometric object, such as a cube, cylinder, sphere, or cone.

[0051] The process of determining the known 3D spatial extent of an object may be performed as an initial step in a method for operating a computed tomography apparatus so that the imaging focus pattern can be determined.

[0052] The term “scouting procedure” as used herein is a broad term, given to those skilled in the art in a normal and customary sense, and is not limited to any special or customized meaning. Specifically, the term may refer, without limitation, to a process of performing at least one radiation measurement to determine the 2D and / or 3D spatial extent of an object.

[0053] The term “user input” as used herein is a broad term, given to those skilled in the art in a normal and customary sense, and not limited to any special or customized meaning. Specifically, the term may refer, without limitation, to user-generated information received by a computed tomography (CT) scanner. User input may be received via a connection interface and / or user input module included in the CT scanner. Thus, a user may input user input into the user input module, for example, by selecting text and / or voice and / or graphical control elements. More specifically, the term user input may refer to information relating to the three-dimensional spatial extent of an object, such as height, length, width, or similar, relating to the object's three-dimensional spatial extent. User input may describe the three-dimensional spatial extent of an object by using geometric objects such as cubes, cylinders, spheres, and cones, and their respective dimensions selected to approximate the object's three-dimensional spatial extent.

[0054] As used herein, the term “CAD model” is a broad term, given to those skilled in the art in a common and customary sense, and is not limited to any special or customized meaning. Specifically, the term may refer, without limitation, to a geometric model of an object produced using computer-aided design (CAD) software. Specifically, a CAD model may include data relating to the three-dimensional spatial extent of an object.

[0055] The term “3D tomography data” as used herein is a broad term, given to those skilled in the art in a normal and customary sense, and is not limited to any special or customized meaning. Specifically, the term may refer, without limitation, to information contained in at least one known projection image and / or at least one known 3D image recorded in a previous computed tomography scan.

[0056] The scouting procedure may include the step of performing a PSS at multiple different field of view, where the PSS may use a scout scan pattern that includes one or more focal positions on at least one target. One or more X-ray focal positions on at least one target may be selected to determine the edges of an object. The scouting procedure may further include the step of constructing a bounding box around the object for each of the multiple different field of view. The known 3D spatial extent of the object may be approximated by using the bounding box.

[0057] The term “scout scan pattern” as used herein is a broad term, given to those skilled in the art in a normal and customary sense, and is not limited to any special or customized meaning. Specifically, the term may, without limitation, refer to a particular arrangement of at least two focal positions for a given field of view. Different X-ray emission cones can be generated by adjusting the focal positions as defined by the scout pattern. Different X-ray emission cones can illuminate different parts of an object. The X-ray cones generated for different focal positions encompass different measurement fields extending from the X-ray emission source to the detector. The different measurement fields define a composite measurement field. With respect to a scout scan pattern selected to determine the edges of an object, the scout scan pattern may be selected in such a way that the composite measurement field encompasses the object so that the edges can be determined.

[0058] The computed tomography system may preferably have a variable geometry such that the distance between the object and the X-ray source and / or the distance between the object and the detector is variable.

[0059] The term “CT apparatus geometry” as used herein is a broad term, given to those skilled in the art in a normal and customary sense, and is not limited to any special or customized meaning. Specifically, the term may refer, without limitation, to the spatial arrangement of components included in a CT apparatus. Components may be, or include, at least one of objects, X-ray sources, and detectors. The geometry of the CT apparatus may be variable, specifically as part of a method for operating the computed tomography apparatus, such that the arrangement of the components can be adjusted. By adjusting the arrangement of the components, the distance between objects and detectors and / or the distance between X-ray sources and detectors and / or the distance between X-ray sources and objects can be adjusted.

[0060] The scouting procedure may further include the step of adjusting the zoom of the computed tomography apparatus. Preferably, the zoom can be adjusted by adjusting the distance between the object and the X-ray source and / or by adjusting the distance between the object and the detector in such a way that the portion of the object covered by the X-ray cone increases. Preferably, the portion of the object covered by the X-ray cone can be increased so that the object can be fully captured in a single projection image, so that only one focal scouting position is required to determine the edges of the object and construct a bounding box.

[0061] Typically, an object is placed between the X-ray source and the detector. As a result, the object may be placed within the measurement field. The “measurement field” can be the volume encompassed by the X-ray radiation, and the detector may be susceptible to the X-ray radiation within that volume. The term “zoom” as used herein is a broad term and is given a common and customary meaning to those skilled in the art, and is not limited to any special or customized meaning. The X-ray cone generated for a particular focal position encompasses the measurement field extending from the X-ray source to the detector.

[0062] Specifically, depending on the size of the object, it may not be fully encompassed by the measurement field described above. Rather, only a portion of the object may be encompassed.

[0063] The variable geometry of a computed tomography (CT) scanner can be adjusted to control the zoom of the scanner. The variable geometry may allow adjustment of the position of at least one of the following: an object, an X-ray source, or a detector within the CT scanner. This allows adjustment of the portion of the object encompassed by the measurement field. The measurement field may be adjusted in such a way that the portion of the object encompassed by the measurement field is increased, preferably contrary to the constraints defined by the geometry of the CT scanner. For example, the variable geometry of the CT scanner may be adjusted so that the measurement field encompasses the volume of the object and / or the entire object being reconstructed. This may minimize the number of projection images that need to be generated in the scouting procedure.

[0064] As already shown, the method may include the step of determining a variable X-ray focal position on at least one target by using the known 3D spatial extent of an object. The X-ray focal position may be an absolute X-ray focal position. The determination may require evaluating the known 3D spatial extent of the object and the relative positions of the X-ray source, the object, and / or the detector.

[0065] The focal pattern can be selected in such a way that the entire volume of the object to be reconstructed is adequately irradiated. In other words, each portion of the volume to be reconstructed can be irradiated by an X-ray cone beam associated with at least one focal point included in the focal pattern. This constraint can define which focal patterns are possible based on the known 3D spatial extent of the object and the relative positions of the X-ray source, the object, and / or the detector.

[0066] The method may further include the step of determining the maximum distance between adjacent X-ray focal points on at least one target in the imaging focal pattern, such that when PSS is performed, the entire volume of the object to be reconstructed can be irradiated by different X-ray emission cones. The maximum distance may be constant between any pair of adjacent X-ray focal points included in the imaging focal pattern. Here, the step of determining the maximum distance may be performed by evaluating the known 3D spatial extent of the object and the relative positions of the X-ray emission source, the object, and / or the detector.

[0067] The portion of the object to be irradiated can be defined by the distance between the object and the X-ray source. The maximum distance between X-ray focal points is: A method for minimizing the overlap between parts of an object irradiated by different X-ray emission cones, and This can be determined by the method by which the entire volume of the object being reconstructed is irradiated. The relative arrangement of X-ray focal positions on targets can be determined by determining the maximum distance between X-ray focal positions on at least one target in the imaging focal pattern.

[0068] The term “maximum distance between adjacent X-ray focal points” as used herein is a broad term, given to those skilled in the art in a normal and customary sense, and not limited to any special or customized meaning. Specifically, the term may, without limitation, refer to at least the spatial relationship between focal points. The maximum distance between adjacent X-ray focal points may refer to the physical distance between two particular focal points such that the portions of an object irradiated by the corresponding X-ray emission cones are in contact with each other and have a direct connection between their geometric centers without any further X-ray emission cones associated with further X-ray focal points in between.

[0069] The method may further include a step of determining the minimum number of X-ray focal positions on at least one target required for the imaging focal pattern so that the entire volume of the object to be reconstructed is irradiated when PSS is performed. Here, the step of determining the minimum number of X-ray focal positions may be performed by evaluating the known 3D spatial extent of the object and the relative positions of the X-ray source, the object, and / or the detector.

[0070] Furthermore, determining the maximum distance between adjacent X-ray focal positions on at least one target in the imaging focus pattern can be used to determine the minimum number of X-ray focal positions on at least one target. Therefore, the relative arrangement of X-ray focal positions on the target can be aligned on the target so that the absolute arrangement of X-ray focal positions on the target is known. This allows for the determination of the absolute focal positions in the imaging focus pattern.

[0071] Alternatively, the minimum number of X-ray focal points may be determined directly, without determining the maximum distance between X-ray focal points, by means of trial and error and / or by implementing a regression algorithm.

[0072] The maximum distance between X-ray focal positions on at least one target in the imaging focus pattern and the minimum number of X-ray focal positions in the imaging focus pattern can be determined for each field of view of the different fields of view of the TSS. As a result, the absolute focal positions in the imaging focus pattern can be determined for each field of view. The absolute focal positions in the imaging focus pattern may differ for each field of view.

[0073] The imaging focus pattern can be changed to a horizontal line pattern when it is only necessary to widen the field of view across the detector's axis. Alternatively, the imaging focus pattern can be changed to a vertical line pattern when it is only necessary to widen the field of view in the detector's axial direction. Overlay may also be possible.

[0074] In a further embodiment, a computed tomography apparatus is disclosed, comprising at least one X-ray source configured to generate an X-ray emission cone for irradiating an object. Furthermore, the computed tomography apparatus comprises at least one detector configured to detect the X-ray emission of the X-ray emission cone as it interacts with the object. The X-ray source comprises at least one electron-optical device configured to variably position at least one electron beam at a plurality of focal positions on at least one target contained in the X-ray source, such that a plurality of different X-ray emission cones emerging from a focal point are generated for imaging different parts of an object. The computed tomography apparatus is configured to carry out methods as disclosed elsewhere in this specification. Any disclosures herein, in particular any definitions, embodiments, and / or further embodiments disclosed elsewhere in this specification can be referenced.

[0075] In further embodiments, a computer program is disclosed. The computer program includes instructions that cause the computed tomography apparatus to perform the method, as disclosed elsewhere in this Specification, once the instructions are executed by the computed tomography apparatus. Any disclosure in this Specification, in particular any definitions, embodiments, and / or further embodiments disclosed elsewhere in this Specification, may be referenced.

[0076] In further embodiments, a computer-readable storage medium is disclosed. Specifically, a non-temporary computer-readable medium is disclosed which, once an instruction is executed by the computed tomography apparatus as disclosed elsewhere in this Specification, includes instructions causing the computed tomography apparatus to perform the method as disclosed elsewhere in this Specification. Any disclosure in this Specification, in particular any definitions, embodiments, and / or further embodiments disclosed elsewhere in this Specification, can be referenced.

[0077] As used herein, the term “computer-readable storage medium” may specifically refer to non-temporary data storage means such as hardware storage media on which computer executable instructions are stored. Specifically, computer-readable storage medium may be, or include, storage media such as random-access memory (RAM) and / or read-only memory (ROM).

[0078] As used below, the terms “have,” “comprise,” or “include,” or any grammatical variations thereof, are used in a non-exclusive manner. Thus, these terms can refer to both situations in which the entity described in relation to the feature introduced by these terms has no further features other than those introduced by these terms, and situations in which one or more further features exist. For example, the expressions “A has B,” “A comprises B,” and “A includes B” can refer to both situations in which A has no other elements other than B (i.e., A consists solely and exclusively of B), and situations in which entity A has one or more further elements other than B, such as element C, elements C and D, or yet another element.

[0079] Furthermore, it should be noted that the terms “at least one,” “one or more,” or similar expressions indicating that a feature or element may exist once or more times, are typically used only once when introducing each feature or element. In most cases below, when referring to each feature or element, the expressions “at least one” or “one or more” will not be repeated, despite the fact that each feature or element may exist once or more times.

[0080] Furthermore, the terms “preferably,” “more preferably,” “particularly,” “more particularly,” “specifically,” “more specifically,” or similar terms, as used below, are used in combination with optional features without limiting the possibility of alternatives. Thus, features introduced by these terms are optional features and are not intended to limit the scope of the claims in any way. The present invention may be carried out by using alternative features, as will be recognized by those skilled in the art. Similarly, features introduced by “in embodiments of the present invention” or similar expressions are intended to be optional features without any limitation on alternative embodiments of the present invention, without any limitation on the scope of the present invention, and without any limitation on the possibility of combining such introduced features with other optional or non-optional features of the present invention.

[0081] The proposed method for operating a computed tomography scanner, the scanner itself, the computer program, and the computer-readable storage medium may offer more advantages than known methods and apparatus.

[0082] Typically, the field of view of a detector is limited by the size of the detector, i.e., the active area. If the field of view is too small to adequately project an object onto the detector, state-of-the-art techniques allow for the movement of the detector or the object, specifically relative to the X-ray source, to achieve different viewpoints on the object and extract additional information from rejected areas not visible in a single field of view. Typically, the detector is moved within the gantry. The detector can be moved by an offset value, leaving overlap between field of view angles, so that the recorded projection images can be stitched together into a common projection image. In fact, as long as the field of view covers the entire 360°, it may be sufficient to completely reconstruct a CT image from even just one of the recorded projection images. Tuy's condition can ensure that every point in the CT image is "viewable" from at least 180°.

[0083] A drawback of this method is that it requires the physical movement of the detector, which can be time-consuming and prone to mechanical inaccuracies. Instead, the method proposed herein positions the X-ray source target such that the focus is created at slightly different locations, resulting in different scanning geometries. These different scanning geometries may enable the collection of relevant data, allowing all information to be gathered as if the detector had been moved. This can be left as part of 3D image reconstruction to ensure that individual projection images are used correctly with respect to the actual scanning geometries.

[0084] This disclosure aims to expand the field of view of an X-ray imaging system by replacing the mechanical movement of the detector with the displacement of the X-ray focal point. X-ray focus adjustment can be achieved by the electron beam optics in the X-ray source, eliminating the need for the slow and potentially inaccurate mechanical movement of the detector. Moving the focal point allows for sampling of different portions of an object volume, which might otherwise not fit a single cone-beam projection onto the detector. The X-ray focus can be moved in steps until the entire volume of the object is covered by multiple cone beams. If the X-ray focus can be moved in 2D, both the radial and axial fields of view can be expanded.

[0085] In contrast to FOV expansion methods that use mechanical movement of the detector, focus shifting methods can result in significant overlap of the X-ray emission cones at different focal positions. This can lead to oversampling of objects compared to systems with stationary X-ray focus and detectors. The additional information from oversampling can be used during the image reconstruction process to improve the signal-to-noise ratio, resolution, and / or overall image quality.

[0086] In summary, without prejudice to further possible embodiments, the following embodiments may be envisioned:

[0087] Embodiment 1: A method for operating a computed tomography apparatus, wherein the computed tomography apparatus comprises at least one X-ray emission source configured to generate an X-ray emission cone for irradiating an object, the computed tomography apparatus comprises at least one detector configured to detect the X-ray emission of the X-ray emission cone interacting with the object, the X-ray emission source comprises at least one electron-optical device configured to variably position at least one electron beam at a plurality of focal positions on at least one target contained in the X-ray emission source, such that a plurality of different X-ray emission cones emerging from the focal point are generated to image different parts of the object, and the method is as follows: A step of performing a projection image scanning sequence (PSS) by using an imaging focus pattern to generate multiple projection images, wherein the imaging focus pattern includes multiple X-ray focal positions on at least one target such that the volume of the object to be reconstructed is irradiated by X-ray emission cones of different volumes; The process involves performing a tomographic scanning sequence (TSS) by performing a projection image scanning sequence (PSS) at different field of view angles, The process includes the step of performing an image reconstruction algorithm using a projected image to reconstruct a 3D image of an object.

[0088] Embodiment 2: The method according to Embodiment 1, wherein the imaging focus pattern is varied in such a way that the X-ray focal position on at least one target is variable.

[0089] Embodiment 3: The method according to Embodiment 2, comprising the step of determining a variable X-ray focal position on at least one target by using a known 3D spatial extent of an object, preferably the known 3D spatial extent is approximated by using a bounding box surrounding the object, and the variable X-ray focal position is determined in order to expand the field of view of the detector to cover the entire volume of the object to be reconstructed.

[0090] Embodiment 4: Steps for carrying out the scouting procedure, A process of receiving user input related to the known 3D spatial extent of an object. A step of determining the known 3D spatial extent of an object by at least one of the steps of receiving data related to the 3D spatial extent of an object, wherein the data related to the 3D spatial extent of an object is Data of object models, such as CAD models of objects. The method according to Embodiment 3, further comprising the step of selecting from at least one of existing 3D tomography data or data representing the 3D volume of an object, such as volumetric data.

[0091] Embodiment 5: The method according to Embodiment 4, wherein the known 3D spatial extent of the determined object is the approximate 3D spatial extent of the object, and in particular, the approximate 3D spatial extent of the object includes at least one simplified geometric object, such as a cube, cylinder, sphere, or cone.

[0092] Embodiment 6: The scouting procedure is The method according to Embodiment 5, comprising the step of performing PSS at multiple different field angles, wherein the PSS uses a scout scan pattern that includes one or more focal positions on at least one target, and the one or more X-ray focal positions on at least one target are selected to determine the edges of an object.

[0093] Embodiment 7: The scouting procedure is, The method according to Embodiment 6, further comprising the step of constructing a bounding box around an object for each of several different field of view angles, wherein the known 3D spatial extent of the object is approximated by using the bounding box.

[0094] Embodiment 8: The computed tomography apparatus preferably has variable geometry such that the distance between the object and the X-ray source and / or the distance between the object and the detector is variable, and the scouting procedure is The method according to Embodiment 7, preferably further comprising the step of adjusting the zoom of the computed tomography apparatus by adjusting the distance between the object and the X-ray source and / or the distance between the object and the detector, in such a way that the portion of the object covered by the X-ray cone increases so that only one focal scouting position is required to determine the edges of the object and construct a bounding box, thereby capturing the object completely in a single projection image.

[0095] Embodiment 9: The method according to any one of Embodiments 4 to 8, wherein when PSS is performed, a step is to determine the maximum distance between X-ray focal positions on at least one target in an imaging focal pattern such that the entire volume of the object to be reconstructed is irradiated by different X-ray emission cones, the step of determining the maximum distance is further performed by evaluating the known 3D spatial extent of the object and the relative positions of the X-ray emission source, the object, and the detector.

[0096] Embodiment 10: The method according to any one of Embodiments 4 to 9, comprising the step of determining the minimum number of X-ray focal positions on at least one target required in the imaging focus pattern so that the entire volume of the object to be reconstructed is irradiated when PSS is performed, further comprising the step of determining the minimum number of X-ray focal positions by evaluating the known 3D spatial extent of the object and the relative positions of the X-ray source, the object, and the detector.

[0097] Embodiment 11: The method according to any one of Embodiments 1 to 10, wherein the maximum distance between X-ray focal positions on at least one target in the imaging focus pattern and the minimum number of X-ray focal positions in the imaging focus pattern are determined for each field of view of different fields of view of the TSS.

[0098] Embodiment 12: The method according to any one of Embodiments 1 to 11, wherein when it is necessary to widen only the axial field of view of the detector, the imaging focus pattern deteriorates to a horizontal line pattern, or when it is necessary to widen only the axial field of view of the detector, the imaging focus pattern deteriorates to a vertical line pattern.

[0099] Embodiment 13: The method according to any one of Embodiments 1 to 12, wherein the step of determining a 3D image of an object by using an image reconstruction algorithm includes the steps of evaluating each captured projection image and, for each projection image, using the X-ray focal position on at least one target from which each projection image was captured.

[0100] Embodiment 14: The method according to Embodiment 13, wherein the image reconstruction algorithm is at least one iterative reconstruction algorithm, or includes at least one iterative reconstruction algorithm.

[0101] Embodiment 15: The method according to Embodiment 13 or 14, wherein the image reconstruction algorithm is at least one analytical reconstruction algorithm, or includes at least one analytical reconstruction algorithm.

[0102] Embodiment 16: Computed tomography apparatus comprising: at least one X-ray emission source configured to generate an X-ray emission cone for irradiating an object; at least one detector configured to detect the X-ray emission of the X-ray emission cone interacting with the object; at least one electron-optical device configured to variably position at least one electron beam over a plurality of focal positions on at least one target included in the X-ray emission source, such that a plurality of different X-ray emission cones emerging from a focal point are generated for imaging different parts of an object; and the computed tomography apparatus is configured to carry out the method according to any one of Embodiments 1 to 15.

[0103] Embodiment 17: A computer program which, when an instruction is executed by a computed tomography apparatus in accordance with an embodiment referring to a computed tomography apparatus, includes an instruction causing the computed tomography apparatus to perform the method described in any one of Embodiments 1 to 15 referring to the method.

[0104] Embodiment 18: A computer-readable storage medium, specifically a non-temporary computer-readable medium, which, when an instruction is executed by a computed tomography apparatus in accordance with an embodiment referring to a computed tomography apparatus, includes an instruction causing the computed tomography apparatus to perform the method described in any one of Embodiments 1 to 15 referring to the method.

[0105] Further optional features and embodiments are disclosed in more detail in the following description of embodiments, preferably in conjunction with dependent claims, where each optional feature can be implemented in any feasible combination as well as in an independent manner, as will be understood by those skilled in the art. The scope of the present invention is not limited by preferred embodiments. Embodiments are schematically shown in the drawings. The same reference numerals in these drawings refer to the same or functionally equivalent elements. [Brief explanation of the drawing]

[0106] [Figure 1] An exemplary computed tomography (CT) scanner is shown. [Figure 2] This document illustrates an exemplary method for operating a computed tomography (CT) scanner. [Figure 3] Further illustrative computed tomography (CT) scanners are shown. [Modes for carrying out the invention]

[0107] Figure 1 shows an exemplary computed tomography (CT) scanner 150, which comprises at least one X-ray source 131 configured to generate an X-ray emission cone 132 for irradiating an object 134. Furthermore, the CT scanner comprises at least one detector 136 configured to detect the X-ray emission from the X-ray emission cone 132 as it interacts with the object 134.

[0108] The X-ray emission source 131 includes at least one electron-optical device 138 configured to variably position at least one electron beam 140 over multiple focal point 142 positions on at least one target 144 included in the X-ray emission source 131, such that multiple different X-ray emission cones 136 emerging from a focal point 142 are generated to image different parts of an object 134. The electron beam 140 is typically generated by using an electron gun 146 included in the X-ray emission source 131.

[0109] The computed tomography scanner 150 may include a control unit 152 that can be operably connected to at least one electron-optical device 138 to adjust the focal position of the electron beam 140 on the target 144. Furthermore, the control unit 152 may be operably connected to a detector 136.

[0110] Furthermore, Figure 1 shows two exemplary trajectories of the electron beam 140 in solid and dashed line styles. The two exemplary emerging X-ray emission cones 136 encompass the entire cross-section of object 134, representing a portion of the volume of object 134 to be reconstructed. Object 134 may be approximated by a bounding box 148, but not limited to, as illustrated in Figure 1. Doing so expands the field of view of the detector 136, thereby maintaining the relative arrangement between the detector 136 and the X-ray emission source 131.

[0111] The computed tomography scanner 150 is configured to perform the method 110 for operating the computed tomography scanner 150.

[0112] Figure 2 shows an exemplary method 110 for operating the computed tomography scanner 150. This method is A step of performing a projection image scanning sequence (PSS) by using an imaging focus pattern to generate multiple projection images, wherein the imaging focus pattern includes multiple X-ray focal positions on at least one target 144 (indicated by reference no. 112) such that the volume of the object 134 to be reconstructed is irradiated by X-ray emission cones 132 with different volumes, The process involves performing a tomographic scanning sequence (TSS) by performing a projection image scanning sequence (PSS) at different field of view angles (as shown in reference number 114), The process includes the step of performing an image reconstruction algorithm using a projected image to reconstruct a 3D image of an object (as shown in reference number 116). Steps 112 and 114 may be repeated to increase the number of projected images so that the resolution of the 3D image increases as a result of providing additional projected images of the object.

[0113] The imaging focus pattern can be varied in such a way that the X-ray focal position on at least one target is variable.

[0114] The method may further include the step of determining a variable X-ray focal position on at least one target 144 by using a known 3D spatial extent of an object (indicated by reference no. 130). Preferably, the known 3D spatial extent can be approximated by using a bounding box 148 surrounding the object 134, and the variable X-ray focal position can be determined in order to expand the field of view of the detector 136 to cover the entire volume of the object 134 to be reconstructed.

[0115] This method is The process of carrying out scouting procedures, A process of receiving user input related to the known 3D spatial extent of an object. A step of determining the known 3D spatial extent of an object by at least one of the steps of receiving data relating to the 3D spatial extent of an object (indicated by reference no. 118), wherein the data relating to the 3D spatial extent of an object is Data of object models, such as the CAD model of object 134. The process may further include selecting from at least one of existing 3D tomography data or data representing the 3D volume of an object, such as volumetric data.

[0116] The known 3D spatial extent of the determined object may be the approximate 3D spatial extent of the object. In particular, the approximate 3D spatial extent of the object may include at least one simplified geometric object, such as a cube, cylinder, sphere, or cone.

[0117] The scouting procedure may include the step of performing a PSS at multiple different field of view angles (indicated by reference no. 120), where the PSS may use a scout scan pattern that includes one or more focal positions on at least one target 144. One or more X-ray focal positions on at least one target 144 may be selected to determine the edges of object 134.

[0118] The scouting procedure may further include the step of constructing a bounding box around object 134 for each of several different field of view angles (indicated by reference no. 122). The known 3D spatial extent of the object can be approximated by using the bounding box.

[0119] Preferably, the computed tomography apparatus 150 may have variable geometry such that the distance between the object 134 and the X-ray emission source 131 and / or the distance between the object 134 and the detector 136 is variable.

[0120] The scouting procedure may further include the step of adjusting the zoom of the computed tomography apparatus 150 (indicated by reference no. 124). Preferably, the zoom can be adjusted by adjusting the distance between the object 134 and the X-ray source 131 and / or by adjusting the distance between the object 134 and the detector 136, such that the portion of the object 134 covered by the X-ray cone 132 increases. Preferably, the portion of the object 134 covered by the X-ray cone 132 can be increased so that the object 134 can be fully captured in a single projection image, such that only one focal scouting position is required to determine the edges of the object 134 and construct the bounding box 148.

[0121] The method may further include a step of determining the maximum distance between X-ray focal positions on at least one target 144 in the imaging focal pattern (indicated by reference no. 126) so that when PSS is performed, the entire volume of the object 134 to be reconstructed can be irradiated by different X-ray emission cones 132. Here, the step of determining the maximum distance may be performed by evaluating the known 3D spatial extent of the object and the relative positions of the X-ray emission source 131, the object 134, and the detector 136. In order to determine variable X-ray focal positions (indicated by reference no. 130), the step of determining the maximum distance between X-ray focal positions (indicated by reference no. 126) may be performed. Consequently, the step of determining variable X-ray focal positions (indicated by reference no. 130) may include the step of determining the maximum distance between X-ray focal positions (indicated by reference no. 126).

[0122] The step of determining the maximum distance between X-ray focal points 142 (indicated by reference no. 126) is illustrated in Figure 3. Figure 3 shows an object 134 that is again approximated by a bounding box 148. In this illustrative case, the object 134 cannot be completely covered by two X-ray emission cones 132. As a result, more than two X-ray emission cones 132 are required. In such cases, an imaging focal pattern can be determined that minimizes the number of X-ray emission cones 132 required to adequately illuminate the object 134 or its approximate bounding box 148. This may require determining the maximum distance between X-ray focal points 142.

[0123] As already shown, the maximum distance between the X-ray focal points 142 can be determined by evaluating the known 3D spatial extent of object 134, which can be approximated by using the bounding box 148, and the relative positions of the X-ray emission source 131, object 134, and detector 136. As can be derived from Figure 3, the intersection of the two X-ray emission cones 132 emerging from the X-ray focal points 142 should not occur within object 134, but rather outside of object 134 or at its edges.

[0124] The method may further include a step of determining the minimum number of X-ray focal positions on at least one target required for the imaging focal pattern so that the entire volume of the object to be reconstructed is irradiated when PSS is performed (indicated by reference no. 128). Here, the step of determining the minimum number of X-ray focal positions may be performed by evaluating the known 3D spatial extent of the object and the relative positions of the X-ray emission source 131, the object 134, and the detector 136. The step of determining the minimum number of X-ray focal positions (indicated by reference no. 128) may be performed to determine variable X-ray focal positions (indicated by reference no. 130). Consequently, the step of determining variable X-ray focal positions (indicated by reference no. 130) may include the step of determining the minimum number of X-ray focal positions (indicated by reference no. 128).

[0125] The maximum distance between X-ray focal positions on at least one target in the imaging focus pattern and the minimum number of X-ray focal positions in the imaging focus pattern can be determined for each field of view of different fields of view of the TSS.

[0126] The imaging focus pattern can be changed to a horizontal line pattern when it is only necessary to widen the field of view across the detector's axis. Alternatively, the imaging focus pattern can be changed to a vertical line pattern when it is only necessary to widen the field of view across the detector's axis.

[0127] The step of determining a 3D image of object 134 by using an image reconstruction algorithm may include the steps of evaluating each captured projection image and, for each projection image, using the X-ray focal position on at least one target 144 from which each projection image was captured. The image reconstruction algorithm may be at least one iterative reconstruction algorithm or may include at least one iterative reconstruction algorithm. Furthermore, the image reconstruction algorithm may be at least one analytical reconstruction algorithm or may include at least one analytical reconstruction algorithm. [Explanation of symbols]

[0128] 110 Method for operating a computed tomography scanner 112 Process for performing a Projection Image Scanning Sequence (PSS) 114 Process of performing a tomographic scanning sequence (TSS) 116 Process of implementing the image reconstruction algorithm 118 Process for determining the 3D spatial extent of an object 120 Process of performing PSS at multiple viewing angles 122 Process of constructing a bounding box 124. Process for adjusting the zoom of the CT scanner. 126 Process for determining the maximum distance between X-ray focal points 128. Process for determining the minimum number of X-ray focal positions. 130 Steps for determining the variable X-ray focal position 131 X-ray radiation source 132 X-ray emission cone 134 Object 136 detectors 138 Electro-optical device 140 Electron beam 142 Focus 144 Targets 146 Electron gun 148 Boundary Box 150 Computed Tomography Scanning Equipment 152 Control Unit

Claims

1. A method for operating a computed tomography apparatus (150), wherein the computed tomography apparatus (150) comprises at least one X-ray emission source (131) configured to generate an X-ray emission cone (132) for irradiating an object (134), the computed tomography apparatus (150) comprises at least one detector (136) configured to detect the X-ray emission of the X-ray emission cone (132) interacting with the object (134), the X-ray emission source (131) comprises at least one electron-optical apparatus (138) configured to variably position at least one electron beam (140) on a plurality of focal positions on at least one target (144) included in the X-ray emission source (131) in such a manner that a plurality of different X-ray emission cones (132) emerging from a focal point are generated to image different parts of the object (134), and the method is A step of performing a projection image scanning sequence (PSS) by using an imaging focus pattern to generate multiple projection images, wherein the imaging focus pattern includes a plurality of X-ray focal positions on at least one target (144) such that the volume of the object (134) to be reconstructed is irradiated by the different X-ray emission cones (132), A step of performing a tomographic scanning sequence (TSS) by performing the projection image scanning sequence (PSS) at different field of view angles, A method comprising the step of performing an image reconstruction algorithm using the projected image to reconstruct a 3D image of the object (134).

2. The method according to claim 1, wherein the imaging focus pattern is varied in such a way that the X-ray focal position on the at least one target (144) is variable.

3. The method according to claim 2, comprising the step of determining a variable X-ray focal position on the at least one target (144) by using a known three-dimensional spatial extent of the object, preferably the known three-dimensional spatial extent is approximated by using a bounding box (148) surrounding the object (134), and the variable X-ray focal position is determined in order to expand the field of view of the detector (136) to cover the entire volume of the object (136) to be reconstructed.

4. The process of carrying out scouting procedures, A step of receiving user input related to the known 3D spatial extent of the object, A step of determining the known 3D spatial extent of an object by at least one of the steps of: receiving data relating to the 3D spatial extent of the object, wherein the data relating to the 3D spatial extent of the object is Data of the object (134), such as a CAD model of the object, The method according to claim 3, further comprising the step of selecting from at least one of existing 3D tomography data or volumetric data, or other data representing the 3D volume of the object (134).

5. The method according to claim 4, wherein the known 3D spatial extent of the determined object is an approximate 3D spatial extent of the object, and in particular the approximate 3D spatial extent of the object includes at least one simplified geometric object, such as a cube, cylinder, sphere, or cone.

6. The aforementioned scouting procedure is The method according to claim 5, comprising the step of performing a PSS at a plurality of different field of view, wherein the PSS uses a scout scan pattern that includes one or more focal positions on the at least one target (144), and the one or more X-ray focal positions on the at least one target (144) are selected to determine the edges of the object (136).

7. The aforementioned scouting procedure is The method according to claim 6, further comprising the step of constructing the bounding box (148) around the object (134) for each of the plurality of different field of view angles, wherein the known 3D spatial extent of the object is approximated by using the bounding box (148).

8. Preferably, the computed tomography apparatus (150) has a variable geometry such that the distance between the object (134) and the X-ray emission source (131) and / or the distance between the object (134) and the detector (136) is variable, and the scouting procedure is The method according to claim 7, preferably further comprising the step of adjusting the zoom of the computed tomography apparatus (150) by adjusting the distance between the object (134) and the X-ray source (131) and / or the detector (136), in such a way that the portion of the object (134) covered by the X-ray cone (132) is increased so that the object (134) is completely captured in a single projection image, such that only one focal scouting position is required to determine the edges of the object (134) and construct the bounding box (148).

9. The method according to any one of claims 4 to 8, wherein, when PSS is performed, a step is to determine the maximum distance between X-ray focal positions on at least one target (144) in the imaging focal pattern such that the entire volume of the object (134) to be reconstructed is irradiated by the different X-ray emission cones (132), the step of determining the maximum distance is further performed by evaluating the known 3D spatial extent of the object and the relative positions of the X-ray emission source (131), the object (134), and the detector (136).

10. The method according to any one of claims 4 to 9, further comprising the step of determining the minimum number of X-ray focal positions on the at least one target (144) required in the imaging focus pattern so that the entire volume of the object to be reconstructed is irradiated when PSS is performed, wherein the step of determining the minimum number of X-ray focal positions is performed by evaluating the known 3D spatial extent of the object and the relative positions of the X-ray emission source (131), the object (134), and the detector (136).

11. The method according to any one of claims 1 to 10, wherein the maximum distance between X-ray focal positions on the at least one target (144) in the imaging focal pattern and the minimum number of X-ray focal positions in the imaging focal pattern are determined for each of the different field angles of the TSS.

12. The method according to any one of claims 1 to 11, wherein the step of determining the 3D image of the object by using the image reconstruction algorithm includes the steps of evaluating each captured projection image and using the X-ray focal position on the at least one target (144) from which each projection image was captured.

13. Computed tomography apparatus (150), wherein the computed tomography apparatus (150) comprises at least one X-ray emission source (131) configured to generate an X-ray emission cone (132) for irradiating an object (134); the computed tomography apparatus (150) comprises at least one detector (136) configured to detect X-ray emission from the X-ray emission cone (132) interacting with the object (134); the X-ray emission source (131) comprises at least one electron-optical apparatus (138) configured to variably position at least one electron beam (140) on a plurality of focal positions on at least one target (144) included in the X-ray emission source (131) such that a plurality of different X-ray emission cones (132) emerging from a focal point are generated for imaging different parts of the object (134); and the computed tomography apparatus (150) is configured to carry out the method according to any one of claims 1 to 12.

14. A computer program comprising an instruction that, when executed by the computed tomography apparatus (150) described in claim 13, causes the computed tomography apparatus (150) to perform the method described in any one of claims 1 to 12.

15. A computer-readable storage medium, specifically a non-temporary computer-readable medium, which, when an instruction is executed by the computed tomography apparatus (150) described in claim 13, includes an instruction causing the computed tomography apparatus (150) to perform the method described in any one of claims 1 to 12.

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