Asymmetric scatter fitting for optimizing panel readout in cone beam computed tomography

Abstract

An x-ray imaging apparatus and associated method are provided for receiving measured projection data in a primary region and measured scatter data in an asymmetric shadow region, and determining an estimated scatter in the primary region based on the measured scatter data in the shadow region. The asymmetric shadow region can be controlled by adjusting the position of the beam aperture center on the readout region of the detector. The half-shadow data can also be used to estimate the scatter in the primary region.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims the benefit of the following eleven U.S. provisional patent applications, including: U.S. provisional patent application serial number 62 / 773,712, filed November 30, 2018 (attorney docket number 38935 / 04001); U.S. provisional patent application serial number 62 / 773,700, filed November 30, 2018 (attorney docket number 38935 / 04002); U.S. provisional patent application serial number 62 / 796,831, filed January 25, 2019 (attorney docket number 38935 / 04004); U.S. provisional patent application serial number 62 / 800,287, filed February 1, 2019 (attorney docket number 38935 / 04003); U.S. provisional patent application serial number 62 / 801,260, filed February 5, 2019 (attorney docket number 38935 / 04006); U.S. provisional patent application serial number 62 / 813,335, filed March 4, 2019 (attorney docket number 38935 / 04007); U.S. provisional patent application serial number 62 / 821,116, filed March 20, 2019 (attorney docket number 38935 / 04009); U.S. provisional patent application serial number 62 / 836,357, filed April 19, 2019 (attorney docket number 38935 / 04016); U.S. provisional patent application serial number 62 / 836,352, filed April 19, 2019 (attorney docket number 38935 / 04017); U.S. provisional patent application serial number 62 / 843,796, filed May 6, 2019 (attorney docket number 38935 / 04005); and U.S. provisional patent application serial number 62 / 878,364, filed July 25, 2019 (attorney docket number 38935 / 04008). This application is also related to ten non-provisional U.S. patent applications filed on the same day, including: non-provisional U.S. patent application entitled “MULTIMODAL RADIATION APPARATUS AND METHODS,” attorney docket number 38935 / 04019; non-provisional U.S. patent application entitled “APPARATUS AND METHODS FOR SCALABLE FIELD OF VIEW IMAGING USING A MULTI-SOURCE SYSTEM,” attorney docket number 38935 / 04020;U.S. Non-Provisional Patent Application entitled "INTEGRATED HELICAL FAN-BEAM COMPUTED TOMOGRAPHY IN IMAGE-GUIDED RADIATION TREATMENT DEVICE" having Attorney Docket No. 38935 / 04011; U.S. Non-Provisional Patent Application entitled "COMPUTED TOMOGRAPHY SYSTEM AND METHOD FOR IMAGE IMPROVEMENT USING PRIOR IMAGE" having Attorney Docket No. 38935 / 04010; U.S. Non-Provisional Patent Application entitled "OPTIMIZED SCANNING METHODS AND TOMOGRAPHY SYSTEM USING REGION OF INTEREST DATA" having Attorney Docket No. 38935 / 04013; U.S. Non-Provisional Patent Application entitled "HELICAL CONE-BEAM COMPUTED TOMOGRAPHY IMAGING WITH AN OFF-CENTERED DETECTOR" having Attorney Docket No. 38935 / 04015; U.S. Non-Provisional Patent Application entitled "MULTI-PASS COMPUTED TOMOGRAPHY SCANS FOR IMPROVED WORKFLOW AND PERFORMANCE" having Attorney Docket No. 38935 / 04021; U.S. Non-Provisional Patent Application entitled "METHOD AND APPARATUS FOR SCATTER ESTIMATION IN CONE-BEAM COMPUTED TOMOGRAPHY" having Attorney Docket No. 38935 / 04012; U.S. Non-Provisional Patent Application entitled "METHOD AND APPARATUS FOR IMPROVING SCATTER ESTIMATION AND CORRECTION IN IMAGING" having Attorney Docket No. 38935 / 04018;and non-provisional U.S. Patent Application entitled "METHOD AND APPARATUS FOR IMAGE RECONSTRUCTION AND CORRECTION USING INTER-FRACTIONAL INFORMATION," having Attorney Docket No. 38935 / 04022. The contents of all of the above-mentioned patent applications and patents are hereby incorporated by reference in their entirety. TECHNICAL FIELD

[0003] Aspects of the disclosed technology relate to estimating scatter in projection data, and more particularly, to estimating scatter in primary region projection data with shadow region data (including asymmetric shadow region / data) from detector readouts, including during cone-beam computed tomography (CT) scans. BACKGROUND

[0004] When no anti-scatter grid is used in a wide collimation opening, scatter in cone-beam CT can account for a significant portion of the detected photons. Scatter can negatively impact image quality, including contrast and quantitative accuracy. Therefore, scatter measurement, estimation, and correction are applicable to cone-beam CT data processing and image reconstruction, including in the context of image-guided radiation therapy (IGRT). IGRT can utilize medical imaging techniques (e.g., CT) to collect images of a patient before, during, and / or after treatment.

[0005] Fitting data in collimator shadows to predict scatter in an opening is an effective scatter estimation method for cone-beam CT (CBCT). Conventionally, this method requires a large amount of data in collimator shadows from both sides of a primary region to achieve a reliable scatter fit. In addition, it can be desirable to reduce the readout range of a detector (panel) to reduce readout time, allowing for scanning at a higher frame rate. SUMMARY

[0006] In one embodiment, estimating scatter in an x-ray image includes receiving measured projection data from a primary region of an x-ray detector, wherein the primary region of the x-ray detector is directly exposed to a beam from a radiation source during at least one scan, receiving measured scatter data from at least one shadow region of the x-ray detector, wherein the at least one shadow region of the x-ray detector is directly blocked from the beam, and determining estimated scatter in the measured projection data based on the measured scatter data in the at least one shadow region, wherein a center of an aperture of the primary region is offset from a center of a readout range during the at least one scan.

[0007] Features described and / or illustrated with respect to one embodiment can be used in the same manner or in an analogous manner in one or more other embodiments and / or in combination with or in place of features of other embodiments.

[0008] The description of the application does not limit the scope of the claims or the scope of the application described in the claims in any way. The word comprising has its plain ordinary meaning. BRIEF DESCRIPTION OF DRAWINGS

[0009] In the drawings, embodiments of the application are illustrated, which are incorporated in and constitute a part of the specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application. It is to be understood that the boundaries of the elements shown in the figures are intended to be only illustrative of one embodiment of the application and that in some embodiments one element can be designed as multiple elements or that multiple elements can be designed as one element. In some embodiments an element shown as an internal component of another element can be implemented as an external component and vice versa. Furthermore, elements can not be drawn to scale.

[0010] Figure 1 is a perspective view of an exemplary x-ray imaging device according to an aspect of the disclosed technology.

[0011] Figure 2 is a schematic view of an x-ray imaging device integrated into an exemplary radiotherapy device according to an aspect of the disclosed technology.

[0012] Figure 3 is a schematic view of an exemplary collimated projection on an x-ray detector.

[0013] Figure 4 is an illustration of an exemplary beam and detector configuration with symmetric shadow read regions.

[0014] Figure 5 is an illustration of an exemplary beam and detector configuration with asymmetric shadow read regions.

[0015] Figure 6 is an illustration of another exemplary beam and detector configuration with asymmetric shadow read regions.

[0016] Figure 7 is an illustration of another exemplary beam and detector configuration with asymmetric shadow read regions.

[0017] Figure 8 is an illustration of an exemplary lung phantom projected onto a detector using exemplary collimator openings.

[0018] Figure 9 is a diagram of an imaging design with a symmetric shadow read region showing a data profile across an exemplary lung phantom. Figure 8 is a data profile of the exemplary lung phantom shown.

[0019] Figure 10 is a diagram of an imaging design with a non-symmetric shadow read region showing a data profile across an exemplary lung phantom. Figure 8 is a data profile of the exemplary lung phantom shown.

[0020] Figure 11 is a diagram of an exemplary lung phantom projected onto a detector using an exemplary collimator opening.

[0021] Figure 12 is a data plot of an exemplary lung phantom with a symmetric shadow read region. Figure 11 shown.

[0022] Figure 13 is a data plot of an exemplary lung phantom with a non-symmetric shadow read region. Figure 11 shown.

[0023] Figure 14 is a diagram of an imaging design showing a data profile across an exemplary lung phantom in a first scan of a dual scan. Figure 8 shown.

[0024] Figure 15 is a diagram of an imaging design showing a data profile across an exemplary lung phantom in a second scan of a dual scan. Figure 8 shown.

[0025] Figure 16 is a flowchart depicting an exemplary method of scatter correction.

[0026] Figure 17 is a flowchart depicting another exemplary method of scatter correction.

[0027] Figure 18 is a flowchart depicting an exemplary method of optimizing a non-symmetric scan design.

[0028] Figure 19 is a flowchart depicting an exemplary method of IGRT using a radiotherapy device.

[0029] Figure 20 is a block diagram depicting exemplary pre-delivery image-based steps.

[0030] Figure 21 is a block diagram depicting exemplary data sources that can be used during imaging or pre-delivery image-based steps. DETAILED DESCRIPTION

[0031] The following includes definitions of example terms that can be used throughout the disclosure. Both singular and plural forms of terms fall within each meaning.

[0032] As used herein, a "component" can be defined as a portion of hardware, a portion of software, or a combination thereof. A portion of hardware can include at least a portion of a processor and a memory including instructions to be executed. A component can be associated with an apparatus.

[0033] As used herein, "logic" synonymous with "circuitry" includes, but is not limited to, hardware, firmware, software, and / or combinations of each to perform a function or action. For example, based on a desired application or need, the logic can include a software controlled microprocessor, discrete logic such as an application specific integrated circuit (ASIC), or other programmed logic device and / or controller. Logic can also be fully embodied as software.

[0034] As used herein, a "processor" includes, but is not limited to, one or more of virtually any number of processor systems or individual processors, such as microprocessors, microcontrollers, central processing units (CPUs), and digital signal processors (DSPs), in any combination. A processor can be associated with various other circuits that support the operation of the processor, such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), a clock, decoders, memory controllers, or interrupt controllers, among others. These support circuits can be internal or external to the processor or its associated electronic package. The support circuits are in operable communication with the processor. The support circuits need not be shown separately in block diagrams or other drawings.

[0035] As used herein, a "signal" includes, but is not limited to, one or more electrical signals (including analog or digital signals), one or more computer instructions, bits or bitstreams, and the like.

[0036] As used herein, "software" includes, but is not limited to, one or more computer readable and / or executable instructions that cause a computer, processor, logic, and / or other electronic device to perform functions, actions, and / or react in a desired manner. The instructions can be embodied in various forms such as routines, algorithms, modules or programs including separate applications or code from dynamically linked source or libraries.

[0037] While the foregoing exemplary definitions have been provided, it is the intention of the Applicant to use the broadest reasonable interpretations consistent with the specification in these and other terms.

[0038] As discussed in more detail below, embodiments of the disclosed technology relate to estimating scatter in imaging projection data, including estimating scatter in primary region projection data using shadow region data during cone-beam CT scanning. In some embodiments, radiation therapy delivery devices and methods can utilize an integrated low-energy radiation source for CT, for use in conjunction with or as part of IGRT. In particular, for example, radiation therapy delivery devices and methods can combine a low-energy collimated radiation source for imaging in a gantry using rotating (e.g., helical or step-and-shoot) image acquisition with a high-energy radiation source for therapeutic treatment.

[0039] Low-energy radiation sources (e.g., kilovolt (kV)) can produce higher quality images compared to imaging with high-energy radiation sources (e.g., megavolt (MV)). Images generated with kV energy generally have better tissue contrast compared to utilizing MV energy. High quality volume imaging can be desirable for visualization of target objects and organs at risk (OARS), adaptive treatment monitoring, and treatment planning / re-planning. In some embodiments, kV imaging systems can also be used for localization, motion tracking, and / or characterization or correction capabilities.

[0040] Image acquisition methods can include or otherwise utilize multiple rotational scans, which can be, for example, continuous scans (e.g., with a helical source trajectory about a central axis and longitudinal movement of the patient support through the gantry aperture), non-continuous circular stop-and-go scans with stepwise longitudinal movement of the patient support, step-and-shoot ring scans, etc.

[0041] According to various embodiments, the imaging device collimates the radiation source into a beam, including, for example, a cone beam or a fan beam, using, for example, a beam shaper. In one embodiment, the collimated beam can be combined with a continuously rotating gantry while the patient is moving, resulting in helical image acquisition.

[0042] In some embodiments, the time associated with increased scan rotation for completing high quality volumetric images can be mitigated by high gantry rates / speeds (e.g., using fast slip ring rotation, including, for example, up to 10 rotations per minute (rpm), 20 rpm, 60 rpm, or higher rpm), high kV frame rates, and / or sparse data reconstruction techniques to provide kV CT imaging on a radiotherapy delivery platform. Detectors (with various row / slice sizes, configurations, dynamic ranges, etc.), scan pitch, and / or dynamic collimation are additional features in various embodiments, including for selectively exposing portions of the detector and selectively limiting the effective read area, as discussed in detail below. In particular, image quality can be improved by using adjustable beam shapers / collimators on the x-ray (low energy) imaging source and / or optimizing the read range of the detector (by estimating scatter, as discussed below).

[0043] Imaging devices and methods can provide selective and variable collimation of a radiation beam emitted by a radiation source, including adjusting the shape of the radiation beam to expose less than the entire active area of an associated radiation detector (e.g., a radiation detector positioned to receive radiation from an x-ray radiation source). For example, a beam shaper of an imaging device can adjust the shape of the radiation beam as the pitch changes during a helical scan. Exposing only a primary area of the detector to direct radiation can cause a shadow area of the detector to receive only scatter. Scatter measurements in the shadow area of the detector (and, in some embodiments, measurements in a penumbra area) can be used to estimate scatter in the primary area of the detector that receives projection data.

[0044] Imaging devices and methods can provide selective and variable detector read areas and ranges, including adjusting the detector read range to limit the active area of the detector to improve read speed. For example, less than the available shadow area data can be read and used for scatter estimation. Combining selective reading with beam shaping allows various optimizations to scatter fitting techniques.

[0045] Reference is made to Figure 1 and Figure 2 , an imaging device 10 (e.g., an x-ray imaging device) is shown. It should be understood that the x-ray imaging device 10 can be associated with a radiotherapy apparatus (like a linear accelerator) or other imaging device (e.g., a CT scanner, an MRI scanner, etc.). The x-ray imaging device 10 includes a radiation source 12 (e.g., an x-ray tube) and a radiation detector 14 (e.g., a flat panel detector). The radiation source 12 and the radiation detector 14 are positioned on a gantry 16. The gantry 16 can be a rotating gantry or a stationary gantry. In some embodiments, the gantry 16 can be a rotating gantry that rotates about a patient 18 positioned on a patient support 20. In some embodiments, the gantry 16 can be a stationary gantry that does not rotate about the patient 18. In some embodiments, the gantry 16 can be a rotating gantry that rotates about the patient 18 and a stationary gantry that does not rotate about the patient 18. Figure 2The illustrated) associated and / or integrated into a radiotherapy device that can be used for a variety of applications, including but not limited to IGRT. The x-ray imaging device 10 includes a rotatable gantry system, referred to as gantry 12, which is supported by or otherwise housed in a support unit or housing 14. Gantry herein refers to a gantry system that includes one or more gantries (e.g., a ring or C-shaped arm) that are capable of supporting one or more radiation sources and / or associated detectors as they rotate around a target subject. For example, in one embodiment, a first radiation source and its associated detector can be mounted to a first gantry of the gantry system, and a second radiation source and its associated detector can be mounted to a second gantry of the gantry system. In another embodiment, more than one radiation source and associated detector can be mounted to the same gantry of the gantry system, including for example the case where the gantry system consists of only one gantry. Various combinations of gantries, radiation sources, and radiation detectors can be combined into various gantry system configurations to image and / or treat the same volume within the same device. For example, a kV radiation source and an MV radiation source can be mounted on the same or different gantries of the gantry system and selectively used for imaging and / or treatment as part of an IGRT system. If mounted to different gantries, the radiation sources are capable of independent rotation, but are still capable of simultaneously imaging the same (or nearly the same) volume. As noted above, the rotatable ring gantry 12 can be capable of 10 rpm or higher. The rotatable gantry 12 defines a gantry bore 16 into and through which a patient can move and be positioned for imaging and / or treatment. According to one embodiment, the rotatable gantry 12 is configured as a slip ring gantry for providing continuous rotation of imaging radiation sources (x-rays) and associated radiation detectors while providing sufficient bandwidth for high quality imaging data received by the detectors. The slip ring gantry can eliminate rotation of the gantry in alternating directions in order to wind and unwind cables carrying power and signals associated with the device. Such a configuration can perform continuous helical computed tomography, including CBCT, even if integrated into an IGRT system.

[0046] The patient support 18 is positioned adjacent to the rotatable gantry 12 and is configured to support a patient generally in a horizontal position for longitudinal movement into and to within the rotatable gantry 12. The patient support 18 can move the patient, for example, in a direction perpendicular to the plane of rotation of the gantry 12 (along or parallel to the axis of rotation of the gantry 12). The patient support 18 can be operably coupled to a patient support controller for controlling movement of the patient and the patient support 18. The patient support controller can be synchronized with the rotatable gantry 12 and the radiation source mounted to the rotating gantry for rotation about the longitudinal axis of the patient in accordance with a commanded imaging and / or treatment plan. Once the patient support is positioned in the bore 16, it can also be moved up and down, left and right within a limited range to adjust the patient position for optimal treatment. Axes x, y and z are shown, where, from the front of the gantry 12, the x-axis is horizontal and points to the right, the y-axis points into the plane of the gantry, and the z-axis is vertical and points to the top. The x, y and z axes follow the right-hand rule.

[0047] It will be appreciated that other variations can be employed without departing from the scope of the disclosed technology. For example, the rotatable gantry 12 and the patient support 18 can be controlled such that as the support is controlled to move relative to the rotatable gantry 12 (at a constant or variable speed), the gantry 12 is rotated in a "back and forth" manner (e.g., alternating clockwise and counterclockwise rotation) about the patient supported on the patient support (as opposed to a continuous manner, as described above). In another embodiment, in the case of a continuous step-and-shoot ring scan, the movement (stepping) of the patient support 18 in the longitudinal direction is alternated (shot) with the scanning rotation of the rotatable gantry 12 until the desired volume is captured. The apparatus 10 is capable of volumetric and planar imaging acquisition. For example, in various embodiments, the apparatus 10 can be used to acquire volumetric and / or planar images and perform the associated processing methods described below.

[0048] Various other types of radiation source and / or patient support movement can be utilized to effect relative motion of the radiation source and patient to generate projection data. Non-continuous motion, continuous but variable / non-constant (including linear and non-linear) linear movement, speed and / or trajectory, etc., of the radiation source and / or patient support, and combinations thereof, can be used, including in connection with the various embodiments of the radiation treatment apparatus 10 described above.

[0049] As Figure 2As shown, the x-ray imaging device 10 includes an imaging radiation source 30 coupled to or otherwise supported by the rotatable gantry 12. The imaging radiation source 30 emits a radiation beam (generally indicated at 32) for generating high quality images. In this embodiment, the imaging radiation source is an x-ray source 30 configured as a kilovolt (kV) source (e.g., a clinical x-ray source with an energy level in the range of approximately 20 kV to approximately 150 kV). In one embodiment, the kV radiation source includes a peak photon energy (keV) of up to 150 keV. The imaging radiation source can be any type of transmission source suitable for imaging. For example, the imaging radiation source can be, for example, an x-ray generating source (including those used for CT) or any other means of producing photons with sufficient energy and flux (e.g., a gamma source (e.g., cobalt 57, with a peak energy at 122 keV), an x-ray fluorescence source (e.g., a fluorescence source through the Pb k-line, with two peaks at approximately 70 keV and approximately 82 keV), etc.). For particular embodiments, references herein to x-rays, x-ray imaging, x-ray imaging sources, etc. are exemplary. In other various embodiments, other imaging transmission sources can be used interchangeably.

[0050] The x-ray imaging device 10 can also include another radiation source 20 coupled to or otherwise supported by the rotatable gantry 12. According to one embodiment, the radiation source 20 is configured as a therapeutic radiation source, such as a high energy radiation source for treating a tumor in a patient's body in the region of interest. It should be appreciated that the therapeutic radiation source can be a high energy x-ray beam (e.g., a megavolt (MV) x-ray beam) and / or a high energy particle beam (e.g., an electron beam, a proton beam, or a heavy ion (e.g., carbon) beam) or another suitable form of high energy radiation without departing from the scope of the disclosed technology. In one embodiment, the radiation source 20 includes a peak photon energy (MeV) of 1 MeV or more. In one embodiment, the high energy x-ray beam has an average energy greater than 0.8 MeV. In another embodiment, the high energy x-ray beam has an average energy greater than 0.2 MeV. In another embodiment, the high energy x-ray beam has an average energy greater than 150 keV. Generally, the radiation source 20 has a higher energy level (peak and / or average, etc.) than the imaging radiation source 30.

[0051] In one embodiment, the radiation source 20 is a LINAC that produces therapeutic radiation (e.g., MV), and the imaging system includes a separate imaging radiation source 30 that produces relatively low intensity and lower energy imaging radiation (e.g., kV). In other embodiments, the radiation source 20 can be a radioisotope, such as, for example, cobalt-60, which can typically have an energy greater than 1 MeV. The radiation source 20 can emit one or more radiation beams (generally indicated by 22) toward a region of interest (ROI) within a patient supported on the patient support 18 in accordance with a treatment plan.

[0052] In some embodiments, the radiation sources 20, 30 can be used in conjunction with one another to provide higher quality and better utilized images. In other embodiments, at least one additional radiation source can be coupled to the rotatable gantry 12 and operated to acquire projection data at a peak photon energy different from that of the radiation sources 20, 30.

[0053] Although Figure 1 and Figure 2 The x-ray imaging apparatus 10 is depicted with a radiation source 30 mounted to a ring gantry 12, but other embodiments can include other types of rotatable imaging apparatuses, including, for example, C-arm gantry-based systems and mechanical arm-based systems. In gantry-based systems, the gantry causes the imaging radiation source 30 to rotate about an axis through the isocenter. Gantry-based systems include C-arm gantry, in which the imaging radiation source 30 is mounted in a cantilevered fashion above and rotates about an axis through the isocenter. Gantry-based systems also include a ring gantry, such as the rotatable gantry 12, which has a generally ring shape, with the patient’s body extending through a hole of the ring / ring face, and the imaging radiation source 30 mounted on a perimeter of the ring and rotates about an axis through the isocenter. In some embodiments, the gantry 12 rotates continuously. In other embodiments, the gantry 12 utilizes a cable-based system that rotates and reverses repeatedly.

[0054] A detector 34 (e.g., a two-dimensional planar detector or a curved detector) can be coupled to or otherwise supported by the rotatable gantry 12. The detector 34 (e.g., an x-ray detector) is positioned to receive radiation from the x-ray source 30 and can rotate with the x-ray source 30. The detector 34 can detect or otherwise measure the amount of unattenuated radiation and thus infer the amount of radiation that is actually attenuated due to the patient or an associated patient ROI (compared to the amount of radiation originally generated). As the radiation source 30 rotates around and emits radiation toward the patient, the detector 34 can detect or otherwise collect attenuation data from different angles.

[0055] It will be appreciated that the detector 34 can take a variety of configurations without departing from the scope of the disclosed technology. AsFigure 2 As shown, the detector 34 can be configured as a flat panel detector (e.g., a multi-row flat panel detector). According to another exemplary embodiment, the detector 34 can be configured as a curved detector.

[0056] An aligner or beam shaper assembly (generally indicated as 36) is positioned relative to the imaging (x-ray) source 30 to selectively control and adjust the shape of the radiation beam 32 emitted by the x-ray source 30 to selectively expose a portion or segment of the active area of the detector 34. The beam shaper can also control how the radiation beam 32 is positioned on the detector 34. In one embodiment, the beam shaper 36 can have one degree / dimension of motion (e.g., to form a thinner or wider slit). In another embodiment, the beam shaper 36 can have two degrees / dimensions of motion (e.g., to form various sized rectangles). In other embodiments, the beam shaper 36 can have various other dynamically controlled shapes, including, for example, parallelograms. All of these shapes can be dynamically adjusted during a scan. In some embodiments, the blocking portion of the beam shaper can be rotated and translated.

[0057] The beam shaper 36 can be controlled to dynamically adjust the shape of the radiation beam 32 emitted by the x-ray source 30 in a number of geometric shapes, including, but not limited to, a fan beam or a cone beam, with a beam thickness (width) as low as one detector row width or including multiple detector rows that would only be a portion of the active area of that detector. In various embodiments, the thickness of the beam can expose a larger detector active area of several centimeters. For example, 3-4 centimeters of a 5-6 centimeter detector (measured in the longitudinal direction in the detector plane) can be selectively exposed to the imaging radiation 32. In this embodiment, a 3-4 centimeter projection image data can be captured each read, with approximately 1-2 centimeters of unexposed detector area on one or each side that can be used to capture scatter data, as described below.

[0058] In other embodiments, more or less of the active detector can be selectively exposed to imaging radiation. For example, in some embodiments, the beam thickness can be reduced to a range of about two centimeters, one centimeter, less than one centimeter, or similar, including utilizing smaller detectors. In other embodiments, the beam thickness can be increased to a range of about 4 centimeters, 5 centimeters, more than 5 centimeters, or similar, including using larger detectors. In various embodiments, the ratio of exposed detector area to active detector area can be 30-90% or 50-75%. In other embodiments, the ratio of exposed detector area to active detector area can be 60-70%. However, in other embodiments, various other exposed area sizes and active area sizes or ratios of exposed detector area to active detector area can be suitable. The beam and detector can be configured such that the shadow region of the detector (active but not exposed to direct radiation) is sufficient to capture scatter data outside the penumbra region.

[0059] Various embodiments can include optimization of the features that control selective exposure of the detector (e.g., beam size, beam / aperture center, collimation, pitch, detector read range, detector read center, etc.) such that the data measured is sufficient for both the primary (exposed) region and the shadow region, but also optimized for speed and dose control. The shape / position of the beam shaper 36 and the read range of the detector 34 can be controlled such that the radiation beam 32 from the x-ray source 30 covers the x-ray detector 34 as much or as little as possible based on the particular imaging task and scatter estimation process being performed. Generally, the active region of the detector 34 can be configured such that one or both of the asymmetric shadow regions of the x-ray detector 34 can be read along with the primary region.

[0060] The beam shaper can be configured in various ways to allow it to adjust the shape of the radiation beam 32 emitted by the x-ray source 30. For example, the collimator 36 can be configured to include a set of jaws or other suitable members that define and selectively adjust the size of an aperture through which the radiation beam from the x-ray source 30 can pass in a collimated fashion. According to one example configuration, the collimator 36 can include an upper jaw and a lower jaw, where the upper and lower jaws are movable in different directions (e.g., parallel directions) to adjust the size of the aperture through which the radiation beam from the x-ray source 30 passes and also to adjust the beam position relative to the patient to irradiate only the portion of the patient to be imaged, thereby optimizing the imaging and minimizing the patient dose. For example, the collimator can be configured as a multi-leaf collimator (MLC), which can include a plurality of interleaved leaves that are operable to move to one or more positions between a minimally open or closed position and a maximally open position. It will be appreciated that the leaves can be moved to a desired position to achieve a desired shape of the radiation beam emitted by the radiation source. In one embodiment, the MLC is capable of sub-millimeter aiming accuracy.

[0061] According to one embodiment, the shape of the radiation beam 32 from the x-ray source 30 can be changed during image acquisition. In other words, according to one example implementation, the leaf position and / or aperture width of the beam shaper 36 can be adjusted prior to or during a scan. For example, according to one embodiment, the beam shaper 36 can be selectively controlled and dynamically adjusted during rotation of the x-ray source 30 such that the shape of the radiation beam 32 has sufficient primary / penumbral regions and is adjusted to include only the object of interest (e.g., the prostate) during imaging. The shape of the radiation beam 32 emitted by the x-ray source 30 can be changed during or after a scan according to a desired image acquisition, which can be based on imaging and / or therapy feedback, as discussed in more detail below.

[0062] The detector 24 can be coupled to or otherwise supported by the rotatable gantry 12 and positioned to receive radiation 22 from the therapeutic radiation source 20. The detector 24 can detect or otherwise measure the amount of unattenuated radiation and thus infer the amount of radiation that is actually attenuated due to the patient or associated patient ROI (compared to the amount of radiation that was originally generated). As the therapeutic radiation source 20 rotates around the patient and emits radiation toward the patient, the detector 24 can detect or otherwise collect attenuation data from different angles.

[0063] It will be further appreciated that the therapeutic radiation source 20 can include or otherwise be associated with a beam shaper or collimator. The collimator / beam shaper associated with the therapeutic radiation source 20 can be configured in a variety of ways, similar to the collimator / beam shaper 36 associated with the imaging source 30.

[0064] Therapeutic radiation source 20 can be mounted, configured, and / or moved into the same plane or a different plane (offset) from imaging source 30. In some embodiments, scatter caused by simultaneous activation of radiation sources 20, 30 can be reduced by offsetting the radiation planes.

[0065] When integrated with a radiation therapy device, imaging apparatus 10 can provide images that are used to set up (e.g., align and / or register), plan, and / or guide a radiation delivery procedure (treatment). Typical set up is accomplished by comparing a current (in-treatment) image to pre-treatment image information. Pre-treatment image information can include, for example, x-ray, CT data, CBCT data, magnetic resonance imaging (MRI) data, positron emission tomography (PET) data, or 3D rotational angiography (3DRA) data, and / or any information obtained from these or other imaging modalities. In some embodiments, imaging apparatus 10 can track in-treatment patient, target object, or ROI motion.

[0066] Reconstruction processor 40 can be operably coupled to detector 24 and / or x-ray detector 34. In one embodiment, reconstruction processor 40 is configured to generate patient images based on radiation received by detectors 24, 34 from radiation sources 20, 30. It will be appreciated that reconstruction processor 40 can be configured to perform the methods described more fully below. Apparatus 10 can also include a memory 44 suitable for storing information including, but not limited to, processing and reconstruction algorithms and software, imaging parameters, image data from previous or otherwise previously obtained images (e.g., planning images), treatment plans, and the like.

[0067] Imaging apparatus 10 can include an operator / user interface 48 at which an operator of imaging apparatus 10 can interact with or otherwise control imaging apparatus 10 to provide input relating to scan or imaging parameters, and the like. Operator interface 48 can include any suitable input device, such as a keyboard, mouse, voice-controlled controller, and the like. Imaging apparatus 10 can also include a display 52 or other human-readable element for providing output to an operator of imaging apparatus 10. For example, display 52 can allow an operator to view reconstructed patient images and other information, such as imaging or scan parameters related to operation of imaging apparatus 10.

[0068] As Figure 2As shown, the imaging device 10 includes a controller (generally designated 60) that is operably coupled to one or more components of the device 10. The controller 60 controls the overall functioning and operation of the device 10, including providing power and timing signals to the imaging source 30 and / or the therapeutic radiation source 20, as well as a gantry motor controller that controls the rotational speed and position of the rotatable gantry 12. It will be appreciated that the controller 60 can encompass one or more of a patient support controller, a gantry controller, a controller coupled to the therapeutic radiation source 20 and / or the imaging source 30, a beam shaper 36 controller, a controller coupled to the detector 24 and / or the detector 34, etc. In one embodiment, the controller 60 is a system controller that can control other components, devices, and / or controllers.

[0069] In various embodiments, the reconstruction processor 40, the operator interface 48, the display 52, the controller 60, and / or other components can be combined into one or more components or devices.

[0070] The device 10 can include various components, logic, and software. In one embodiment, the controller 60 includes a processor, a memory, and software. By way of example and not limitation, the x-ray imaging device and / or radiation therapy system can include various other devices and components (e.g., gantry, radiation source, collimator, detector, controller, power supply, patient support, etc.) that can implement one or more routines or steps related to imaging and / or IGRT for a particular application, where the routines can include imaging, pre-treatment image-based steps, and / or radiation treatment delivery, including respective device settings, configurations, and / or positions (e.g., paths / tracks) that can be stored in the memory. Further, the controller can control one or more devices and / or components directly or indirectly in accordance with one or more routines or processes stored in the memory. An example of direct control is the setting of various radiation source or collimator parameters (power, speed, position, timing, modulation, etc.) associated with imaging or treatment. An example of indirect control is communicating positions, paths, speeds, etc. to a patient support controller or other peripheral devices. The hierarchy of various controllers that can be associated with the imaging device can be arranged in any suitable manner to communicate appropriate commands and / or information to the desired devices and components.

[0071] Further, those skilled in the art will appreciate that other computer system configurations can be used with the present system and method. The illustrated aspects of the application can be practiced in distributed computing environments where certain tasks are performed by local or remote processing devices that are linked through a communications network. In one embodiment, for example, the reconstruction processor 40 can be associated with a separate system. In a distributed computing environment, program modules can be located in both local and remote memory storage devices. For example, remote databases, local databases, cloud computing platforms, cloud databases, or combinations thereof can be used with the imaging device 10.

[0072] The imaging device 10 can utilize an exemplary environment to implement various aspects of the present application, including a computer, wherein the computer includes a controller 60 (e.g., including a processor and a memory (which can be the memory 44)) and a system bus. The system bus can couple system components including, but not limited to, the memory to the processor and can communicate with other systems, controllers, components, devices, and processors. The memory can include read-only memory (ROM), random access memory (RAM), hard drives, flash drives, and any other form of computer-readable media. The memory can store various software and data, including routines and parameters, which can include, for example, a treatment plan.

[0073] The therapeutic radiation source 20 and / or the imaging source 30 can be operably coupled to the controller 60, which is configured to control the relative operation of the therapeutic radiation source 20 and the imaging source 30. For example, the imaging source 30 can be controlled and can operate simultaneously with the therapeutic radiation source 20. Additionally or alternatively, depending on the particular treatment and / or imaging plan being implemented, the imaging source 30 can be controlled and can operate sequentially with the therapeutic radiation source 20.

[0074] It will be appreciated that the imaging source 30 and detector 34 can be configured to provide rotation about the patient in a variety of ways during an imaging scan. In one embodiment, synchronizing the motion and exposure of the imaging source 30 with the longitudinal motion of the patient support 18 can provide for continuous helical acquisition of images of the patient during a procedure. In addition to continuous rotation of the radiation source 20, 30 and detector 24, 34 (e.g., gantry continuously and constantly rotates at a constant patient motion speed), it will be appreciated that other variations can be employed without departing from the scope of the disclosed technology. For example, the rotatable gantry 12 and patient support can be controlled such that, as the support is controlled to move (at a constant or variable speed) relative to the rotatable gantry 12, the gantry 12 rotates in a "back and forth" manner (e.g., alternately clockwise and counterclockwise) about a patient supported on the patient support (as opposed to continuously, as described above). In another embodiment, in the case of a continuous step-and-shoot ring scan, movement (stepping) of the patient support 18 in the longitudinal direction is alternated with scanning rotation (shooting) of the rotatable gantry 12 until the desired volume is captured. The imaging device 10 is capable of volumetric and planar imaging acquisition. For example, in various embodiments, the imaging device 10 can be used to acquire volumetric and / or planar images (e.g., by using the imaging source 30 and detector 34) and perform associated processing, including the scatter estimation / correction methods described below.

[0075] Various other types of radiation source and / or patient support movement can be utilized to effect relative motion of the radiation source and patient to generate projection data. Non-continuous motion, continuous but variable / non-constant (including linear and non-linear) movement, speed, and / or trajectory, etc., of the radiation source and / or patient support, as well as combinations thereof, can be used, including in connection with the various embodiments of the radiation therapy device 10 described above.

[0076] In one embodiment, the rotational speed of the gantry 12, the speed of the patient support 18, the shape of the beam shaper 36, and / or the readout of the detector 34 can all remain constant during image acquisition. In other embodiments, one or more of these variables can be dynamically changed during image acquisition. The rotational speed of the gantry 12, the speed of the patient support 18, the shape of the beam shaper 36, and / or the readout of the detector 34 can be changed to balance different factors, including, for example, image quality and image acquisition time.

[0077] In other embodiments, these features can be combined with one or more other image-based activities or procedures, including, for example, patient setup, adaptive therapy monitoring, therapy planning, etc.

[0078] There are many determinants of image quality (e.g., imaging source focal spot size, detector dynamic range, etc.). A limiting factor of kV CBCT image quality is scatter. Various methods can be used to reduce scatter. One method is to use an anti-scatter grid (which collimates scatter). However, implementing a scatter grid on a kV imaging system can be problematic, including for motion tracking and correction. To improve the quality of the image data, it is desirable to accurately estimate scatter in the projection data. In various embodiments, scatter in the projection data acquired in the main region of the detector 34 can be estimated based on data measured in the shadow regions (and penumbra regions) of the detector 34.

[0079] Figure 3 is a schematic diagram of an exemplary collimated projection 300 on an x-ray detector 302. A rotating x-ray source 306 is shown emitting a beam 308 that exposes a main or central (C) region 310 of the detector 302, thereby directing the radiation from the x-ray source 306 (e.g., through a subject object) as the x-ray source rotates about the y-axis. Motion of a patient support (not shown) can be in an axial (longitudinal) direction along the y-axis, including as part of the scan described above. The detector 302 also has a back (B) shadow region 312 and a front (F) shadow region 314 that are blocked from direct exposure to the beam 308 by a beam shaper / collimator 320. The beam shaper / collimator 320 is configured to adjust the shape and / or position of the beam 308 emitted by the x-ray source 306 onto the detector 302. The shadow regions 312, 314 will only receive scattered radiation.

[0080] The collimator 320 is configured such that the back (B) end 312 and the front (F) end 314 of the detector 302 are not illuminated by direct radiation 308 in the axial or longitudinal direction (along the patient table direction or y-axis). These back (B) shadow regions 312 (in the negative longitudinal direction along the rotating y-axis) and front (F) shadow regions 314 (in the positive longitudinal direction along the rotating y-axis) can be used for scatter measurements, as they do not receive direct radiation. For example, the read range of the detector 302 can be configured to read all or part of the data in one or more of the shadow regions 312, 314 and use that data for scatter estimation in the main region 310. The main or central (C) region 310 receives both direct projections and scatter.

[0081] The data processing system (e.g., processor 40) can be configured to receive the measured projection data in the primary region 310 and the measured scatter data in the at least one shadow region 312, 314, and then determine an estimated scatter in the primary region 310 based on the measured scatter data in the at least one shadow region 312, 314. In some embodiments, determining the estimated scatter in the primary region 310 during a current rotation can be based on the measured scatter data in the at least one shadow region 312, 314 during an adjacent (preceding and / or subsequent) rotation. In other embodiments, data measured from the penumbra regions (bordering the primary region and the shadow regions) can also be used for scatter estimation.

[0082] Some embodiments of the collimator shadow fitting method can use a large amount of data from both sides of the collimator shadow regions 312, 314 for scatter fitting. Measuring a large amount of scatter data in the shadow regions 312, 314 can consume a large amount of processing time, but this is not always needed for reliable scatter fitting (estimation). For example, during a CBCT scan, it can be desirable to reduce the readout range of the detector (including the primary region and the shadow regions that are read out) to reduce the readout time, allowing the scan to be performed at a higher frame rate. However, when using a reduced detector readout range and applying scatter estimation fitting using collimator shadow data, some readout range is still needed to be allocated for reading out data in the collimator shadow regions 312, 314. Therefore, in these embodiments, to reduce the readout time, the effective detector area used for patient data acquisition in the primary region 310 is typically reduced, resulting in a reduction of the effective scan field of view. Therefore, when a large axial range of the patient needs to be scanned, additional circular or helical scan rotations will be needed. The total scan time will increase, and the treatment workflow and throughput will be adversely affected.

[0083] However, in various embodiments described herein, the use of asymmetric data fitting for scatter estimation can be used to mitigate the need for reducing the field of view (FOV). For example, some embodiments use a large amount of data from one side of the collimator shadow and use a minimal amount of data from the other side of the collimator shadow, such that the total detector readout range used to read out data for scatter fitting is reduced, effectively increasing the scan FOV when using a limited detector readout range (or maintaining the scan FOV when compared to a non-reduced detector readout range). This can be referred to as asymmetric scatter fitting.

[0084] Figures 4-7A schematic diagram of an exemplary detector in a scanning design with various shaded regions and detector readout ranges is shown. The exemplary detector is positioned to receive radiation from an X-ray source (not shown) emitting a radiation beam, wherein the detector includes a readout range. A beamformer (not shown) is configured to adjust the shape (e.g., width) and position (e.g., center) of the radiation beam emitted by the X-ray source such that the main area of ​​the X-ray detector is directly exposed to the radiation beam, and at least one shaded region of the X-ray detector is blocked by the beamformer so as not to be directly exposed to the radiation beam (e.g., as shown). Figure 3 (As shown).

[0085] For convenience, in these figures, the beam region and detector region are identified using the following symbols along the axial direction (y-axis) of the X-ray imaging device: Let L D For having detector center C D The axial length of the detector; let L A For having an aperture center C A The axial length of the aperture created by the beam shaper; and let L R For having a reading center C R The detector reads the axial length of the (effective) range. Projecting the beam onto the detector creates a range with a length equal to L. A axial length L C The main region, with an axial length L SB The rear shadow area and having an axial length L SF The foreground shadow area. It has an axial length L. PB The posterior hemisphere and having an axial length L PF The anterior penumbra region lies between the principal region and the shadow region. In this way, the beamformer can be configured to project a radiation beam onto the detector, such that L... D =L SB +L PB +L A +L PF +L SF Furthermore, the effective readout area of ​​the detector can be controlled / configured so that only a portion of the shaded area is read (effective), where the axial length of the shaded area after effectiveness is L. B The axial length of the effective foreshadowing region is L. F .

[0086] Figure 4 This is an illustration of an exemplary beam and detector configuration 400 with symmetrically shaded readout regions. In this configuration, detector 402 is shown, with its aperture center C... A and Reading Center C R With detector center C D Alignment. Here, the effective back shadow area LB and effective foreshadowing area L F The lengths are equal and symmetrical on detector 402.

[0087] As described above, in order to optimize readout time, scan speed, dose, etc., various embodiments can utilize asymmetric shaded regions and their associated measurement results, wherein the readout range L R Reading Center C R Deviation from the main region L C (L A The aperture center C A This deviation can be created by changing the shape (size / position) of the beam on the detector and / or by changing the size / position of the detector's read (effective) area. This is to accommodate an optimized or reduced read range L. R , Figures 5-7 The reading range L is shown. R Reading Center C R Deviation from the main region L C Aperture center C A An exemplary embodiment of the present invention enables the effective (reading) of the shadow region L. F L B They are not equal, but sufficient for scattering fitting and estimation.

[0088] In one embodiment, Figure 5 This is an illustration of an exemplary beam and detector configuration 500 with an asymmetric shadow readout region. In this embodiment, the readout range L can be reduced. R However, the reading center C R With detector center C of detector 502 D Alignment. In this embodiment, the beam shaper can adjust the shape of the radiation beam incident on detector 502, so that the main region L... C Aperture center C A Off-center reading C R The deviation is expressed in terms of axial length L. O As shown. In this configuration, the effective back shadow area L B and effective foreshadowing area L F It becomes asymmetrical. Here, the effective backshading area L is shown. B The axial length is greater than the effective foreshadowing region L F The axial length. In other embodiments, the aperture center C A You can be in L F Greater than L B Offset in the opposite direction has a similar effect. Shadow reading area L F L B One or two of them can be used for scatter fitting.

[0089] In another embodiment, Figure 6 is a diagram of another example beam and detector configuration 600 with asymmetric shadowed read regions. In this embodiment, the read range L R may be reduced, where the read center C R is offset from the detector center C D of the detector 602. In this embodiment, the primary region L C has an aperture center C A that is aligned with the detector center C D . The amount of offset is shown as an axial length L O . In this configuration, the effective post-shadow region L B and the effective pre-shadow region L F become asymmetric. Here, the axial length of the effective post-shadow region L B is shown to be greater than the axial length of the effective pre-shadow region L F . In other embodiments, the read center C R may be offset in the opposite direction with L F greater than L B , with similar effects. One or both of the shadowed read regions L F , L B may be used for scatter fitting.

[0090] In another embodiment, Figure 7 is a diagram of another example beam and detector configuration 700 with asymmetric shadowed read regions. In this embodiment, the read range L R may be reduced, where both the read center C R and the aperture center C A are offset from the detector center C D of the detector 702. The net amount of offset between the read center C R and the aperture center C A is shown as an axial length L O . In this configuration, the effective post-shadow region L B and the effective pre-shadow region L F become asymmetric. Here, the axial length of the effective post-shadow region L B is shown to be greater than the axial length of the effective pre-shadow region L F . In other embodiments, the read center C R and the aperture center C A may be offset in the opposite direction with L F greater than L B or have opposite respective offsets, with similar effects. One or both of the shadowed read regions L F , L B may be used for scatter fitting.

[0091] In any of these embodiments, the x-ray imaging device (e.g., imaging device 10) can include a data processing system (e.g., processor 40) configured to receive measured projection data in the primary region L C and measured scatter data in at least one shadow region L F , L B and determine estimated scatter in the primary region L F based on the measured scatter data in the at least one shadow region L B , L C In some embodiments, the data processing system can be configured to receive measured penumbra data in at least one penumbra region L PF , L PB and determine estimated scatter in the primary region L PF based on the measured penumbra data in the at least one penumbra region L PB , L C

[0092] The imaging design can include optimization of the size of the primary region L C and the size of at least one shadow region L F , L B within the read range L R along with optimization of various other imaging considerations (including, for example, read speed, scan speed, scatter estimation algorithms / protocols, machine limitations, etc.), resulting in an asymmetric shadow region configuration. As noted above, in various embodiments, the desired dimensions of regions L C , L F and / or L B may be achieved using a collimator (e.g., beam shaper 36) having the ability to produce variable beam widths on the detector, for example, by means that can be translated and / or rotated to adjust the aperture center C R relative to the detector (e.g., x-ray detector 34) read center C A In some embodiments, the desired dimensions of regions L C , L F and / or L B may be achieved using detector read control (e.g., control size and positioning), via hardware and / or software, separately or in conjunction with the collimator.

[0093] For example, Figure 8 ​is an illustration 800 of an exemplary lung phantom 804 projected onto a detector 802 using an exemplary narrow collimator opening. The central region is the lung phantom 804 exposed to the radiation beam, and the black regions to the left and right are collimator shadows 806. The black dot 808 is a lead bead just in front of the phantom 804. In this configuration, the detector 802 is shown to have an aperture center C A . Projecting the beam aperture onto the detector creates a primary region of axial length L A , a back shadow region of axial length L SB , and a front shadow region of axial length L SF .

[0094] Figure 9 and Figure 10 shows imaging designs 900, 1000 in which the data profiles are along line A-A of an exemplary lung phantom 804 in the detector 802 plane shown in Figure 8 . The horizontal axis of the data profiles is the pixel position on the detector 802 plane. The vertical axis of the data profiles represents the plot of data measured for each pixel along line A-A. The back shadow L SB range on the left of the figure shows the range of data available for scatter estimation (fitting) in the left collimator shadow region. The front shadow L SF range on the right of the figure shows the range of data available for scatter estimation in the right collimator shadow region. The potential read range L R of the detector 802 is shown to have a read center C R . Data outside the read range L R of the detector 802 will not be read and thus is not available. With a limited detector read range, if the collimator opening remains the same, the data available for scatter fitting must be reduced.

[0095] Figure 9 is an illustration of the imaging design 900 with symmetric shadow read regions in which the data profiles are along line A-A of an exemplary lung phantom 804 in the detector 802 plane shown in Figure 8 . In this configuration, the detector 802 is shown to have an aperture center C R aligned with the read center C A . Here, the read range L R of the detector 802 is shown to have a primary region of axial length L C . The effective back shadow region L B and the effective front shadow region L F are equal in length and symmetric on the detector 802. In this embodiment, L B and L FThis represents the typical shaded area size required for a sufficient scattering estimate.

[0096] However, as mentioned above, for example, in order to reduce read time, various embodiments include a reduced read range L for detector 802. R Furthermore, asymmetric shaded regions can be utilized, where the reading range L R Reading Center C R Deviation from the main region L C (L A The aperture center C A .For example, Figure 10 This is an illustration of an imaging design 1000 with an asymmetric shadow reading region, where the data contour is along the span Figure 8 Line AA of the exemplary lung phantom 804 in the plane of detector 802 shown. Here, relative to Figure 9 The reading range L shown R The reading range L of detector 802 R 'Decreases, but the axial length L of the main region' C (FOV) is maintained. Effective post-shading area L B The axial length is also preserved for scattering estimation. This is to accommodate the reduced readout range L. R 'and the same main area L C ,and Figure 9 Effective foreshadowing area L F In comparison, the effective foreshadowing area L F 'Decrease.' Therefore, read center C R 'With aperture center C A (and Figure 9 Reading Center C R ) deviating from L O In this embodiment, the effective back shadow area L B and effective foreshadowing area L F The lengths of the ' are not equal (asymmetric), but are sufficient for scatter fitting and estimation.

[0097] In various embodiments, as described above, the shape (size / position) of the beam on the detector can be changed (e.g., by adjusting the aperture center C of the beam on the detector). A (Shift) and / or by changing the detector read (valid) area L R Size / position to generate aperture center C A With Reading Center C R Deviation between L O .

[0098] In another example, Figure 11This is illustration 1100 of an exemplary lung phantom 1104 projected onto detector 1102 using an exemplary collimator opening. The central region is the lung phantom 1104 exposed to the radiation beam, and the black areas on the left and right sides are collimator shadows 1106. The black dot 1108 is a guide bead positioned directly in front of phantom 1104. In this configuration, detector 1102 is shown with an aperture center C. A Projecting the beam aperture onto the detector creates an axial length of L. A The main area, with an axial length of L SB The back shadow area and the axial length of L SF The foreground shadow area. The background shadow L. SB Range and foreshadow L SF The range shows the range of data that can be used for scatter estimation in collimator shadows.

[0099] Figure 12 and Figure 13 Symmetric and asymmetric scattering fits are shown respectively, with experimental data demonstrating the effectiveness of the disclosed asymmetric scattering fit, which was applied along the transverse direction. Figure 11 The data profile of line AA of an exemplary lung phantom 1104 in the plane of detector 1102 is shown. The horizontal axis of the data profile is the pixel position on the plane of detector 1102, and the vertical axis of the data profile represents a graph of the data measured for each pixel along line AA.

[0100] Figure 12 Data figure 1200 is a data area with symmetrical shaded reading regions, which is along the span Figure 11 The line AA of the exemplary lung phantom 1104 in the plane of detector 1102 is shown. Here, the reading range L of detector 1102 is... R It is shown as having an axial length of L C The main area, and the effective back shadow area L within it. B and effective foreshadowing area L F They are of equal length and symmetrical. In this embodiment, L B and L F This represents the typical shaded area size used for a sufficient scattering estimate.

[0101] Figure 13 The data in Figure 1300 has an asymmetric shaded reading area, which is along the span Figure 11 Line AA of the exemplary lung phantom 1104 in the plane of detector 1102 is shown. Here, relative to... Figure 12 The reading range L shown R The reading range L of detector 1102 R 'Decreases, but the axial length L of the main region'C The axial length of the effective posterior shadow region L B is also maintained for scatter estimation. To accommodate the reduced read range L R ‘and the same primary region L C , Figure 12 The effective anterior shadow region L F compared to the effective anterior shadow region L F ‘is reduced.

[0102] The measured data line 1210 is a line profile along the line A-A in the collimator shadow L SB , L SF extending into the lung phantom 1104. The tail at the end of the measured data line 1210 is in the collimator shadow L SB , L SF . The dip in the measured data line 1210 is a small shadow region in which x-rays are blocked by the guiding bead array 1108 just before the phantom 1104.

[0103] The scatter lines 1220, 1320 are scatter fitted (estimated) in L Figure 12 and L 13 , respectively. The overlapping portion of the measured data line 1210 and the scatter lines 1220, 1320 (identified by the box arrows in the figure) indicates the data from the collimator shadow L B and L F , L F ‘that is used for scatter fitting. The measured data 1210 in the guiding bead 1108 shadow is used as a reference for the post-fitting scatter (after being offset by the penetration by the guiding bead 1108). As shown by the experimental data in L Figure 12 and L 13 , both scatter lines 1220, 1320 are in contact with the dip of the guiding bead 1108 shadow in the curves 1200, 1300. This evidence confirms the effectiveness of the asymmetric scatter fitting / estimation 1320 when compared to the symmetric scatter fitting / estimation 1220 applied to the same measured data 1210.

[0104] In various embodiments, as described above, the offset between the aperture center and the read center can be produced by changing the shape (size / position) of the beam on the detector (e.g., by shifting the aperture center of the beam) and / or by changing the size / position of the detector read (effective) region.

[0105] Although not shown in L Figure 10 and L Figure 13 , in various embodiments, a penumbra region (bordering the primary region and the shadow region, e.g., as shown inFigures 4-7 The middle is shown as L PB and L PF In asymmetric implementations, if the collimator has systemically different penumbras on both sides, the side with the larger penumbra width may be more suitable for a reduced shadow area (e.g., as shown in the image). Figure 10 and 13 The L shown F ').

[0106] In an extreme implementation of asymmetric scattering fitting, the collimator shadow is read from only one side, with no detector region available for reading from the other side. Typically, scattering fitting is ineffective when only data from the collimator shadow is available on one side. In this embodiment, the imaging design implements a dual-scan configuration, where during the first scan, the detector's readout cuts off at the penumbra on one side of the collimator, and during the second scan, the detector's readout cuts off at the penumbra on the other side of the collimator. The first scan includes collimator shadow data available from one side, and the second scan includes collimator shadow data available from the other side.

[0107] For example, in one embodiment, the second scan may include shifting the collimator opening relative to the detector readout region to read the collimator shadow on the other side. In these embodiments, sufficient collimator shadow data is obtained by combining collimator shadow data from one side in the first scan and collimator shadow data from the other side in the second scan, and this data can be used for scattering estimation. This design allows the detector readout range to cut off at the penumbra region on the collimated side during each scan, thereby maximizing the useful scan FOV. Combining the available data can provide scattering estimations as reliable as conventional collimator shadow fitting methods.

[0108] For example, Figure 14 and Figure 15 Imaging designs 1400 and 1500 are shown, where the data profile is along the span Figure 8 Line AA of the exemplary lung phantom 804 in the plane of detector 802 shown. As described above, the shading L on the left side of the figure... SB The range shows the range of data available for scattering estimation (fitting) within the shaded area of ​​the left collimator. The foreground shaded area on the right side of the figure is L. SF The range indicates the range of data available for scattering estimation in the shaded region of the right collimator. The reduced readout range L of detector 802. R It is shown as having an aperture center C A Deviating from L O Reading Center C R .

[0109] Figure 14is an illustration of an imaging design 1400 with asymmetric shadow read regions, where the data profile along line A-A across an example lung phantom 804 is used as a first scan of a dual scan. In this design 1400, the read range L R = L B (+L PB )+L C (+L PF ), where L PB and L PF are half shadow regions that can be used in certain embodiments, as described below. In this way, only one shadow region L B is read for scatter estimation data (as well as the main region L R in read range L C ). Figure 15 is an illustration of an imaging design 1500 with asymmetric shadow read regions, where the data profile along line A-A across an example lung phantom 804 is used as a second scan of a dual scan. In this design 1500, the read range L R = (L PB )+L C (+L PF )+L F . In this way, only the opposite shadow region L F is read for scatter estimation data.

[0110] In one embodiment, shifting the collimator aperture center C A relative to the read center C R of the detector read range L R can maximize (optimize) the effective data acquisition area on the detector in a dual scan method. In the first scan (e.g., as shown in Figure 14 ), the left collimator shadow region L B overlaps with the detector read range L R and provides left side data for scatter fitting, but the detector read range L R is aligned with (cuts off at) the right half shadow L PF (which has been contaminated and has less statistical data for at least CT reconstruction). In the second scan (e.g., as shown in Figure 15 ), the collimator (and its aperture center C A ) is adjusted (e.g., shifted) relative to the detector and its read range L R . The detector read range L R is aligned with (cuts off at) the left half shadow L PB and with the right collimator shadow L FOverlapping is used to provide sufficient data for scattering fitting. By combining data from the left and right shaded regions, sufficient scattering data from the left and right sides of the main region can be used for accurate scattering fitting.

[0111] In this dual-design embodiment, if the first and second scans use different doses (e.g., mA), the collimator shadow data from both scans can be scaled or weighted accordingly before or during the scatter fitting and / or reconstruction process. Furthermore, by using scattering estimated with scaling / weighting associated with the dose of each scan, the projection data measured in the main region can be reconstructed separately for each scan. Moreover, in some embodiments, data from both scans can be jointly reconstructed, for example, by combining data before or during reconstruction, while the estimated scattering is used accordingly for scattering correction.

[0112] In one embodiment, determining the estimated scattering in the measured projection data includes scaling the scattering data measured in at least one shaded region based on differences in doses during the scan. In another embodiment, determining the estimated scattering in the measured projection data includes scaling the projection data measured from a first scan or a second scan based on differences in doses during the scan.

[0113] The penumbra region associated with the collimator (e.g., L) is typically not used in conventional CT or CBCT scans. PB and L PF Typically, the penumbra region on each side of the beam collimator covers the detector range, which is usually approximately the size of the source's focal point multiplied by the magnification. To make the scattering estimation more accurate, the penumbra region of the collimator / beamformer can be excluded. In one embodiment, this can be achieved by automatically detecting the axial profile of each projection and then excluding multiple predetermined pixels in the axial direction. Another approach is to experiment in advance for different window and scanning configurations and predefine the rear and front regions for scattering measurements based on the penumbra region.

[0114] However, in some embodiments, asymmetric scattering estimation techniques can estimate the penumbra region (e.g., L...). PB and / or L PF The scattering in the collimator aperture L is then used to determine the scattering. A Corresponding main area L C Scattering estimation in [the context]. These embodiments reduce the collimator shadow region (e.g., L [the area of ​​the collimator]). B and / or L F The required data for accurate scattering fitting / modeling in the detector, and therefore for a given detector readout range L R It can improve the effective scanning FOV (L)C ). In one embodiment, the collimator side with the smaller shadow region read is the side with the larger penumbra.

[0115] In this way, scatter measured in the penumbra region (e.g., L PB and / or L PF ) can be modeled and used as data for scatter estimation in the primary region (e.g., L C ) corresponding to the collimator opening. This can reduce the amount of data needed for scatter fitting in the collimator shadow region (beyond the penumbra region), allowing more of the detector read range L R to be used for the primary region L C (FOV of the patient scan data).

[0116] For example, if the penumbra in air (P map ) can be accurately measured and mapped, then scatter in the penumbra can be estimated. In one embodiment, a first reconstruction of the image is performed without scatter correction. The estimated projection to the penumbra region (Pp) is computed, and the estimated projection to the opening (Po) is also computed for the pixels next to the penumbra. The measured projection data to the opening (PoM) is scaled and modulated by the penumbra map (PM) to estimate the value that is the modulated primary portion in the penumbra (P_primary) and the scatter in PoM (Po_scatter), where:

[0117]

[0118] Here, denotes the modulation, which for example can be a simple pixel-wise multiplication. The measured value in the penumbra is:

[0119]

[0120] Assuming that the scatter in the penumbra region is the same as the pixels next to the penumbra entering the opening, then there is the following relationship between the scatter in the penumbra and the measured penumbra value and the value of the pixels next to the penumbra entering the collimator opening:

[0121]

[0122] If a simple pixel-wise multiplication is used for the penumbra modulation, then the scatter in the penumbra is:

[0123]

[0124] In one embodiment, an iterative approach can be applied to improve the accuracy of the above techniques. For example, the above process can be performed using the scatter measured from the collimator shadow and the fitted scatter from the penumbra estimation after the first scatter correction. This can result in a more accurate estimation of the scatter in the penumbra, which in turn enables a more accurate scatter estimation.

[0125] In another embodiment, the scatter fit using the scatter obtained in the penumbra can have different weights for the data from the collimator shadow and the data from the penumbra.

[0126] Various techniques and methods can utilize different scan geometries, detector positioning, and / or beam shaper window shapes. In some embodiments, the detector can also be offset in the lateral direction.

[0127] The following flowcharts and block diagrams illustrate exemplary configurations and methods associated with scatter estimation according to the above-described systems. The exemplary methods can be performed in logic, software, hardware, or combinations thereof. In addition, although the procedures and methods are presented in a particular order, the blocks can be performed in different orders, including serially and / or in parallel. Thus, although shown sequentially, the following steps (including imaging, pre-delivery image-based steps, and radiotherapy delivery) can be performed concurrently, including in real-time. Moreover, additional steps or fewer steps can be used.

[0128] Figure 16 is a flowchart describing an exemplary method 1600 of scatter estimation and correction using an asymmetric scan design (e.g., those described above). The input can include any optional prior data and / or scan design. In this embodiment, step 1610 includes data acquisition. For example, during a rotation of a radiation source projecting a collimated radiation beam toward a target object and a radiation detector, the method measures projection data (primary + scatter) in a central (primary) region of the radiation detector and measures scatter using a pre-shadow peripheral region and / or a post-shadow peripheral region of the detector. In these embodiments, the aperture center of the primary region is offset from the read center of the read range during the scan such that the pre- and post-shadow regions are asymmetric (including the case where only one shadow region is used), in accordance with any of the embodiments described above.

[0129] The data acquisition in step 1610 can also include adjusting the shape / position of the radiation beam by the beam shaper prior to and / or during the scan. Adjusting the radiation beam by the beam shaper can include rotating and translating the height x-ray attenuating material of the beam shaper to block radiation from directly exposing the shadow region during the scan. Step 1610 can also include adjusting the read range (including shifting the active area). Adjusting the radiation beam and / or read range can be used to create an asymmetric shadow region by shifting the aperture center of the primary region and the read center of the x-ray detector.

[0130] Next, step 1620 includes scatter estimation. For example, according to any of the embodiments described above, the method uses scatter measurements from the shadow region and / or penumbra region to estimate scatter in the projection data from the central (primary) region. Then, step 1630 includes scatter correction. For example, the scatter estimated from step 1620 is subtracted from the projection data to obtain scatter corrected projection data. The output includes the scatter corrected projection data suitable for imaging. Various embodiments can utilize different scan geometries, detector positioning / active area, beam shaper positioning / window shape, etc.

[0131] Figure 17 is a flowchart depicting an exemplary method 1700 of scatter estimation and correction using an asymmetric scan design with a first scan and a second scan (e.g., those described above). The input can include any optional prior data and / or scan design. In this embodiment, step 1710 includes data acquisition during the first scan, where the method measures projection data in the central (primary) region of the radiation detector and measures scatter in a first shadow region of the detector. Next, at step 1720, the method adjusts the position of the radiation beam between the first scan and the second scan. For example, step 1720 can adjust the beam so that the first shadow region overlaps a first side of the detector read range during the first scan and a second shadow region overlaps a second side of the read range during the second scan. Then, step 1730 includes data acquisition during the second scan, where the method measures projection data in the central (primary) region of the radiation detector and measures scatter in a second shadow region of the detector. Then, at step 1740, the method can combine the scatter data measured from the first shadow region and the second shadow region, including by using various model fitting techniques. In some embodiments, step 1740 can be skipped or combined with step 1750.

[0132] Next, step 1750 includes scatter estimation, in which the method uses scatter measurements from the first and second shadow regions to estimate scatter in the projection data from the central (main) region. Then, step 1760 includes scatter correction, in which the method subtracts the estimated scatter from the projection data to obtain scatter-corrected projection data. The output includes the scatter-corrected projection data suitable for imaging. Like the steps of method 1600, the steps of method 1700 can be implemented according to any of the above-described embodiments.

[0133] One or more optimization processes can also be applied to all of the above-described embodiments to determine beam positioning, determine read ranges, estimate scatter, etc. For example, in one embodiment, Figure 18 is a flowchart depicting an exemplary method 1800 of optimizing an asymmetric scan design, such as those described above. One constraint and / or objective during optimization can be a target object or reduced read time. As described above, reducing the read range of the detector (including the main shadow region and the read shadow region) can reduce read time, allowing for scanning at a higher frame rate. However, when using a reduced detector read range and applying scatter estimation using collimator shadow data fitting, it can be desirable to allocate a minimum or target read range to read data in the collimator shadow regions. Total scan time, treatment workflow, and / or throughput can be additional factors. Step 1810 includes determining beam positioning. Step 1820 includes determining detector read range. In some embodiments, steps 1810 or 1820 can be optional, limiting optimization to the other variable. In other embodiments, steps 1810 and 1820 can be performed in a particular order, simultaneously, and / or iteratively. For example, one step can be performed to reach an initially optimized design, and then another step can be performed in view of the other step, or vice versa, including iteratively, to optimize the design. Then at step 1830, the scan design can be implemented as described above.

[0134] Figure 19is a flowchart depicting an exemplary method 1900 of IGRT using a radiation treatment device, including, for example, imaging apparatus 10. Prior image data 1905 of the patient can be available, which can be a previously acquired planning image, including a prior CT image. Prior data 1905 can also include a treatment plan, phantom information, models, a priori information, etc. In some embodiments, prior image data 1905 is generated by the same radiation treatment device but at an earlier time. At step 1910, imaging of the patient is performed using a low energy radiation source (e.g., kV radiation from x-ray source 30). In one embodiment, the imaging includes a helical scan with fan-beam or cone-beam geometry. Step 1910 can produce high quality (HQ) images or imaging data 1915 using the scatter estimation and correction techniques described above. In some embodiments, the image quality can be adjusted to optimize a balance between image quality / resolution and dose. In other words, not all images need to have the highest quality, or the image quality can be adjusted to optimize or trade off a balance between image quality / resolution and image acquisition time. Imaging step 1910 can also include image processing for generating patient images based on the imaging data (e.g., according to the methods described above). Although image processing step 1920 is shown as part of imaging step 1910, in some embodiments, image processing step 1920 is a separate step, including performing image processing by a separate device.

[0135] Next, at step 1930, one or more pre-delivery image-based steps discussed below are performed based at least in part on imaging data 1915 from step 1910. As discussed in more detail below, step 1930 can include determining various parameters associated with the treatment and (subsequent) imaging plan. In some embodiments, the pre-delivery image-based steps (1930) can require more imaging (1910) prior to the radiation delivery (1940). Step 1930 can include adjusting the treatment plan based on imaging data 1915 as part of an adaptive radiation treatment routine. In some embodiments, the pre-delivery image-based steps 1930 can include real-time treatment planning. Embodiments can also include simultaneous, overlapping, and / or alternating activation of the imaging and therapeutic radiation sources. Real-time treatment planning can involve any or all of these types of imaging and therapeutic radiation activation techniques (simultaneous, overlapping, and / or alternating).

[0136] Next, at step 1940, a therapeutic treatment delivery is performed using a high energy radiation source (e.g., MV radiation from therapeutic radiation source 20). Step 1940 administers a therapeutic dose 1945 to the patient according to the treatment plan. In some embodiments, IGRT method 1900 can include returning to step 1910, such that additional imaging is performed at various intervals, followed by image-based pre-delivery steps (1930) and / or radiation delivery (1940) as needed. In this way, high quality imaging data 1915 can be generated and utilized using one device 10 capable of adaptive therapy during IGRT. As described above, steps 1910, 1920, 1930, and / or 1940 can be performed simultaneously, overlapping, and / or alternating.

[0137] IGRT can include at least two overall goals: (i) deliver a highly conformal dose distribution to a target volume; (ii) deliver the radiation therapy beam with high accuracy throughout the course of each treatment fraction. A third goal can be to accomplish both overall goals in as little time per fraction as possible. Accurate delivery of the radiation therapy beam requires the ability to identify and / or track the location of the target volume within the fraction through high quality images. The ability to increase the speed of delivery requires the ability to move the radiation source accurately, precisely, and quickly according to the treatment plan.

[0138] Figure 20 is a block diagram 2000 depicting example pre-delivery image-based steps / options that can be associated with above step 1930. It will be understood that the above imaging device 10 (e.g., as part of a radiation therapy apparatus) can generate kV images that can be used in a variety of ways, including for pre-delivery image-based steps (1930), without departing from the scope of the present application. For example, images 1915 generated by the radiation therapy apparatus can be used to align the patient prior to treatment (2010). Patient alignment can include correlating or registering current imaging data 1915 with imaging data associated with earlier pre-treatment scans and / or plans, including the treatment plan. Patient alignment can also include feedback regarding the physical location of the patient relative to the radiation source to verify that the patient is within range of the delivery system. If necessary, the patient can be adjusted accordingly. In some embodiments, patient alignment imaging can be purposefully of lower quality to minimize dose but provide sufficient alignment information.

[0139] The images generated by imaging device 10 can also be used for treatment planning or re-planning (2020). In various embodiments, step 2020 can include confirming a treatment plan, modifying a treatment plan, generating a new treatment plan, and / or selecting a treatment plan (sometimes referred to as a“daily plan”) from a set of treatment plans. For example, if the imaging data 1915 indicates that the target volume or ROI is the same as when the treatment plan was made, the treatment plan can be confirmed. However, if the target volume or ROI is different, the treatment can need to be re-planned. In the case of re-planning, because of the high quality of the imaging data 1915 (generated by x-ray imaging device 10 at step 1910), the imaging data 1915 can be used for treatment planning or re-planning (e.g., generating a new or modified treatment plan). In this way, pre-treatment CT imaging via a different device is not needed. In some embodiments, confirmation and / or re-planning can be ongoing procedures before and / or after various treatments.

[0140] According to another example use case, the images generated by imaging device 10 can be used to calculate imaging dose (2030), which can be used for ongoing determination of total dose to the patient and / or for subsequent imaging planning. The quality of subsequent imaging can also be determined as part of the treatment planning, e.g., to balance quality and dose. According to another example use case, the images generated by imaging device 10 can be used to calculate treatment dose (2040), which can be used for ongoing determination of total dose to the patient and / or can be included as part of the treatment planning or re-planning.

[0141] According to other example use cases, the images generated by imaging device 10 can be used in conjunction with planning or adjusting other imaging (2050) and / or other treatment (2060) parameters or plans, e.g., including as part of adaptive treatment and / or treatment plan generation. According to another example use case, the images generated by imaging device 10 can be used in conjunction with adaptive treatment monitoring (2070), which can include monitoring of radiation delivery and adaptive adjustment as needed.

[0142] It will be appreciated that the image-based steps prior to delivery (1930) are not mutually exclusive. For example, in various embodiments, calculating treatment dose (2040) can itself be a step and / or can be part of adaptive treatment monitoring (2070) and / or treatment planning (2020). In various embodiments, the image-based steps prior to delivery (1930) can be performed automatically and / or manually with the involvement of a human.

[0143] The above-described apparatus and methods, including adjustable collimation of image radiation and scatter estimation and correction schemes, provide improved scatter estimation, which results in higher quality images for kV generation compared to conventional in-treatment imaging systems, such as CBCT.

[0144] Figure 21 is a block diagram 2100 depicting exemplary data sources that can be used during imaging 1910 and / or subsequent image-based steps prior to delivery 1930. Detector data 2110 represents all data received by the image radiation detector 34. Projection data 2120 is data generated by radiation incident in the collimated beam region (referred to above as the primary or central region). Penumbra data 2130 is data generated by radiation incident in the penumbra region. Scatter data 2140 is data generated by radiation incident in the peripheral region outside the penumbra region (referred to above as the shadow region).

[0145] In one embodiment, the penumbra data 2130 can be used to separate or identify projection and / or scatter data. As described in detail above, the scatter data 2140 can be used to estimate scatter radiation in the projection data 2120. In another embodiment, the scatter data 2140 can be used to determine the residual effects of scatter from the therapeutic radiation source 20 (e.g., MV) when the two sources 20, 30 are operated simultaneously or in an interleaved fashion.

[0146] In this manner, the penumbra data 2130 and / or scatter data 2140 can be used to improve the quality of the images generated by the imaging step 1910. In some embodiments, the penumbra data 2130 and / or scatter data 2140 can be combined with the projection data 2120 and / or can be analyzed in accordance with applicable imaging settings 2150, treatment settings 2160 (e.g., if simultaneous imaging and therapeutic radiation), and any other data 2170 associated with the imaging apparatus 10 at the time the data was collected at the imaging detector 34. In other embodiments, this data can be used in the treatment planning step 1930.

[0147] While the disclosed technology has been illustrated and described in relation to certain aspects, one or more embodiments, it is readily apparent to those of ordinary skill in the art that modifications and adaptations of the disclosed technology can be made without departing from the scope of the present disclosure. In particular, with respect to the various functions performed by the above described elements (components, assemblies, devices, means, compositions, etc.), the terms (including a reference to an "apparatus") used to describe certain disclosed examples are used as terms of approximation and not as terms of limitation, unless otherwise expressly limited by context. For example, the term "apparatus" is used to refer to any element (e.g., a device, a component, an assembly, a means, a composition, etc.) that performs the specified function (i.e., is functionally equivalent) of the described element, unless otherwise explicitly indicated. Additionally, although a particular feature of the disclosed technology can have been described in relation to only one or a few illustrated aspects or embodiments, the feature can be combined with one or more other features of other aspects, embodiments, and modifications in any combination per the desires of the user. For example, an apparatus of one aspect can comprise any of the features of one or more other aspects or embodiments.

[0148] While the embodiments discussed herein have been in relation to the systems and methods discussed above, these embodiments are intended to be exemplary and are not intended to limit the applicability of these embodiments to only those discussions set forth herein. Although the present application has been described in relation to the embodiments thereof, and although the embodiments have been described in some detail, it is not the intention of the applicant to limit or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the application in its broader aspects is not limited to the specific details, representative apparatus, and illustrative examples shown and described. Accordingly, departures can be made from such details without departing from the spirit or scope of applicant's general inventive concept.

Claims

1. An X-ray imaging device, comprising: A rotating X-ray source used to emit a radiation beam; An X-ray detector is positioned to receive radiation from the X-ray source, wherein the detector includes a readout range; A beam shaper is configured to adjust the shape of a radiation beam emitted from the X-ray source such that a major region of the X-ray detector is directly exposed to the radiation beam, and at least one shadowed region of the X-ray detector is blocked by the beam shaper so as not to be directly exposed to the radiation beam. During the entire scan, data is collected from both the main region and the at least one shaded region; Wherein, the aperture center of the main region is offset from the reading center of the reading range; and The X-ray imaging device further includes a data processing system configured as follows: Receive measured projection data in the main region and measured scattering data in the at least one shadow region; and Based on the measured scattering data in the at least one shaded region, the estimated scattering in the main region is determined.

2. The X-ray imaging device according to claim 1, wherein, The data processing system is also configured to: Receive measured penumbra data in at least one penumbra region; and Based on the measured penumbra data in the at least one penumbra region, the estimated scattering in the main region is determined.

3. The X-ray imaging device according to claim 1, wherein, The beam shaper adjusts the position of the radiation beam so that the aperture center of the main region is offset from the detector center of the X-ray detector.

4. The X-ray imaging device according to claim 1, wherein, The reading center of the reading range is offset from the detector center of the x-ray detector.

5. The X-ray imaging device according to claim 1, wherein, The beam shaper adjusts the position of the radiation beam such that the aperture center of the main region is offset from the detector center of the x-ray detector, and wherein the readout center of the readout range is offset from the detector center of the x-ray detector.

6. The X-ray imaging device according to claim 1, wherein, The at least one shadow region of the X-ray detector includes a rear shadow region having a rear axial length and a front shadow region having a front axial length, wherein the rear axial length is not equal to the front axial length.

7. A method for estimating scattering in an X-ray image, comprising: Receive projection data measured from the main region of an X-ray detector, wherein the main region of the X-ray detector is directly exposed to a radiation beam from a radiation source during at least one scan, and the detector includes a readout range; Receive scattering data measured from at least one shadowed region of the x-ray detector, wherein the at least one shadowed region of the x-ray detector is blocked from direct exposure to the radiation beam; and Based on the measured scattering data in the at least one shaded region, determine the estimated scattering in the measured projection data. During the entire scan, data is collected from both the main region and the at least one shaded region; During the at least one scan, the aperture center of the main region deviates from the reading center of the reading range.

8. The method according to claim 7, further comprising: The position of the radiation beam is adjusted so that the aperture center of the main region is offset from the reading center of the X-ray detector.

9. The method according to claim 7, wherein, The at least one scan includes a first scan and a second scan, and wherein the at least one shaded region includes a first shaded region and a second shaded region, the method further includes: The position of the radiation beam is adjusted between the first scan and the second scan such that during the first scan, the first shadow region overlaps with a first side of the readout range, and during the second scan, the second shadow region overlaps with a second side of the readout range; The estimated scattering in the measured projection data is determined based on the measured scattering data in the first shadow region and the second shadow region.

10. The method according to claim 9, wherein, During the first scan, the second side of the reading range is aligned with the first penumbra region, which is opposite to the first shadow region, and during the second scan, the first side of the reading range is aligned with the second penumbra region, which is opposite to the second shadow region.

11. The method according to claim 9, wherein, The first scan includes a first radiation dose, and the second scan includes a second radiation dose that is different from the first radiation dose.

12. The method according to claim 11, wherein, Determining the estimated scattering in the measured projection data includes scaling the measured scattering data in at least one of the first shadow region or the second shadow region based on the difference between the first radiation dose and the second radiation dose.

13. The method according to claim 11, wherein, Determining the estimated scattering in the measured projection data includes scaling the measured projection data from at least one of the first scan or the second scan based on the difference between the first radiation dose and the second radiation dose.

14. The method according to claim 9, wherein, Determining the estimated scattering in the measured projection data includes reconstructing the measured projection data jointly from the first scan and the second scan.

15. The method of claim 7, further comprising: Receive measured penumbra data in at least one penumbra region; as well as Based on the measured penumbra data in the at least one penumbra region, the estimated scattering in the main region is determined.

16. The method according to claim 15, wherein, Determining the estimated scattering in the main region based on the measured penumbra data in the at least one penumbra region includes: determining the estimated scattering in the main region pixels adjacent to the penumbra region pixels.

17. The method according to claim 16, wherein, Determining the estimated scattering in the main region based on the measured penumbra data in the at least one penumbra region includes an iterative process.

18. The method according to claim 15, wherein, Determining the estimated scattering in the primary region includes: applying different weights to the measured penumbra data in the at least one penumbra region and the measured scattering data in the at least one shadow region.

19. A radiotherapy application device, comprising: A rotatable gantry system, positioned at least partially around the patient support; A first radiation source is coupled to the rotatable gantry system, and the first radiation source is configured as a therapeutic radiation source; A second radiation source is coupled to the rotatable gantry system, and the second radiation source is configured as an imaging radiation source with an energy level lower than that of the therapeutic radiation source; A radiation detector is coupled to the rotatable gantry system and positioned to receive radiation from the second radiation source; A beamformer is configured to shape the radiation beam emitted by the second radiation source such that a primary region of the radiation detector is directly exposed to the radiation beam, and at least one shadowed region of the radiation detector is blocked by the beamformer and thus not directly exposed to the radiation beam, wherein data from both the primary region and the at least one shadowed region are collected throughout the scan; and The data processing system is configured as follows: Receive measured projection data in the main region and measured scattering data in the at least one shadow region; and Based on the measured scattering data in the at least one shaded region, an estimated scattering in the main region is determined, wherein the aperture center of the main region is offset from the reading center of the reading range; Based on the estimated scattering, a patient image is reconstructed; and During adaptive image-guided radiotherapy (IGRT), a therapeutic radiation dose is delivered to the patient via the first radiation source based on the patient image.

Images