Multi-mode radiation device and method

Abstract

The multi-modal imaging apparatus and method include a rotatable gantry system with multiple radiation sources including different energy levels (e.g., kV and MV). Fast slip ring technology and spiral scanning allow data from multiple radiation sources to be combined or utilized to generate improved images and workflows, including improved images and workflows for IGRT. Features include improving the accuracy of spatial registration between corresponding image sets to allow more accurate radiation therapy irradiation, reducing image artifacts (e.g., scatter, metal and beam hardening, image blur, motion, etc.), and utilizing dual energy imaging (e.g., for material separation and quantitative imaging, patient settings, online adaptive IGRT, etc.).

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of 11 U.S. provisional patent applications, including: U.S. Provisional Patent Application Serial No. 62 / 773,712 filed on November 30, 2018 (Agent Docket No. 38935 / 04001); U.S. Provisional Patent Application Serial No. 62 / 773,700 filed on November 30, 2018 (Agent Docket No. 38935 / 04002); U.S. Provisional Patent Application Serial No. 62 / 773,712 filed on November 30, 2018 (Agent Docket No. 38935 / 04002); U.S. Provisional Patent Application Serial No. 62 / 796,831 (Agent Docket No. 38935 / 04004), filed February 1, 2019; U.S. Provisional Patent Application Serial No. 62 / 800,287 (Agent Docket No. 38935 / 04003), filed February 5, 2019; U.S. Provisional Patent Application Serial No. 62 / 801,260 (Agent Docket No. 38935 / 04006), filed March 4, 2019; U.S. Provisional Patent Application Serial No. 62 / 813,335 filed on March 20, 2019 (Agent Docket No. 38935 / 04007); U.S. Provisional Patent Application Serial No. 62 / 821,116 filed on March 20, 2019 (Agent Docket No. 38935 / 04009); U.S. Provisional Patent Application Serial No. 62 / 836,357 filed on April 19, 2019 (Agent Docket No. 38935 / 04016); U.S. Provisional Patent Application Serial No. 62 / 836,352, filed on April 19, 2019 (Agent Docket No. 38935 / 04017); U.S. Provisional Patent Application Serial No. 62 / 843,796, filed on May 6, 2019 (Agent Docket No. 38935 / 04005); and U.S. Provisional Patent Application Serial No. 62 / 878,364, filed on July 25, 2019 (Agent Docket No. 38935 / 04008). The present application is also related to ten non-provisional U.S. patent applications filed on the same day, including: a non-provisional U.S. patent application with attorney docket number 38935 / 04020 entitled “APPARATUS AND METHODS FOR SCALABLE FIELDOF VIEW IMAGING USING A MULTI-SOURCE SYSTEM”; a non-provisional U.S. patent application with attorney docket number 38935 / 04011 entitled “INTEGRATED HELICAL FAN-BEAM COMPUTED TOMOGRAPHY IN IMAGE-GUIDED RADIATION TREATMENT DEVICE”;Non-Provisional U.S. Patent Applications Attorney Docket No. 38935 / 04010, entitled “COMPUTED TOMOGRAPHY SYSTEM AND METHOD FOR IMAGE IMPROVEMENT USING PRIOR IMAGE”; Non-Provisional U.S. Patent Applications Attorney Docket No. 38935 / 04013, entitled “OPTIMIZED SCANNING METHODS AND TOMOGRAPHY SYSTEM USING REGION OF INTERESTDATA”; Non-Provisional U.S. Patent Applications Attorney Docket No. 38935 / 04015, entitled “HELICAL CONE-BEAM COMPUTED TOMOGRAPHY IMAGING WITH AN OFF-CENTERED and U.S. Patent Application No. 38935 / 04014, entitled “ASYMMETRIC SCATTER FITTING FOR OPTIMAL PANEL READOUT IN CONE-BEAM COMPUTED TOMOGRAPHY”; and U.S. Patent Application No. 38935 / 04021, entitled “MULTI-PASS COMPUTED TOMOGRAPHY SCANS FOR IMPROVED WORKFLOW AND PERFORMANCE”; and U.S. Patent Application No. 38935 / 04012, entitled “METHOD AND APPARATUS FOR SCATTER ESTIMATION IN CONE-BEAM COMPUTED TOMOGRAPHY”; and U.S. Patent Application No. 38935 / 04014, entitled “ASYMMETRIC SCATTER FITTING FOR OPTIMAL PANEL READOUT IN CONE-BEAM COMPUTED TOMOGRAPHY”. TOMOGRAPHY (ASYMMETRIC SCATTER FITTING FOR OPTIMIZING PANEL READING IN CONE BEAM COMPUTED TOMOGRAPHY)”; and attorney docket number 38935 / 04018, entitled “METHOD AND APPARATUS FOR IMPROVING SCATTER ESTIMATION AND CORRECTION INIMAGING”;and non-provisional U.S. patent application with attorney docket number 38935 / 04022, entitled “METHOD AND APPARATUS FOR IMAGE RECONSTRUCTION AND CORRECTION USING INTER-FRACTIONAL INFORMATION.” The contents of all of the above-mentioned patent(s) and patent(s) are incorporated herein by reference in their entirety. ; Technical Field

[0003] Various aspects of the disclosed technology relate to imaging using multi-modal radiation, and more particularly, to combining low energy radiation (e.g., kilovolts (kV)) and high energy radiation (e.g., megavolts (MV)) for improved imaging, including for computed tomography (CT) scanning. Background Art

[0004] Pathological anatomy such as tumors and lesions can be treated by invasive procedures such as surgery, which may be harmful and full of risks for patients. A non-invasive method for treating pathological anatomy (e.g., tumors, lesions, vascular malformations, neurological disorders, etc.) is external beam radiotherapy, which generally uses a therapeutic radiation source such as a linear accelerator (LINAC) to generate a radiation beam (e.g., x-ray). In one type of external beam radiotherapy, a therapeutic radiation source guides a series of x-ray beams to the tumor site from multiple angles with the patient in the field of view of the beam. As the angle of the therapeutic radiation source changes, each beam passes through the tumor site, but passes through different areas of healthy tissue on its way to the tumor and from the tumor. As a result, the cumulative radiation dose at the tumor is high, while the cumulative radiation dose to healthy tissue is relatively low.

[0005] The term "radiosurgery" refers to an operation in which radiation is applied to a target area in a dose sufficient to necrotize the condition in fewer treatment stages or fractions compared to delivery in more treatment stages or fractions with a lower dose per fraction. Unlike radiotherapy, radiosurgery is typically characterized by a relatively high radiation dose per fraction (e.g., 500-2000 centigrays) and large doses in fewer fractions (e.g., 1-5 fractions or treatment days). Radiotherapy is typically characterized by low doses per fraction (e.g., 100-200 centigrays) and hyperfractionated radiotherapy (e.g., 30-45 fractions). For convenience, unless otherwise noted, the terms "radiotherapy" and "radiotherapy" are used interchangeably herein to refer to radiosurgery and / or radiotherapy.

[0006] Image guided radiation therapy (IGRT) systems include gantry-based systems and robotic arm-based systems. In gantry-based systems, the gantry rotates a therapeutic radiation source around an axis passing through the isocenter. Gantry-based systems include C-arm gantry, in which the therapeutic radiation source is mounted in a cantilevered manner on an axis passing through the isocenter and rotates around the axis passing through the isocenter. Gantry-based systems also include annular gantry, which has a generally annular shape, in which the patient's body extends through the hole of the ring / annulus, and the therapeutic radiation source is mounted on the periphery of the ring and rotates around the axis passing through the isocenter. Conventional gantry systems (annular or C-arm) apply therapeutic radiation at a set angle, which is defined by the rotation trajectory of the radiation source. In robotic arm-based systems, the therapeutic radiation source is mounted on an articulated robotic arm that extends above and around the patient, and the robotic arm is configured to provide at least five degrees of freedom. Robotic-based systems provide the ability to deliver therapeutic radiation from multiple out-of-plane directions, ie, non-coplanar delivery is possible.

[0007] Associated with each radiation therapy system is an imaging system that provides in-treatment images used to establish and, in some examples, guide the radiation delivery process and track in-treatment target motion. For setup and in-treatment images, MV imaging systems may place a detector opposite the treatment source to image the patient, while other approaches utilize (one or more) unique and independent image radiation sources and / or (one or more) detectors for patient setup and in-treatment images. Target or target volume tracking during treatment is accomplished by comparing the in-treatment images with previous treatment image information or pre-treatment image information. Pre-treatment image information may include, for example, CT data, cone beam CT (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 imaging modalities (e.g., but not limited to, digitally reconstructed radiographs (DRRs)).

[0008] In a common scenario, the treatment source is a LINAC (which may be, for example, an MV source) that produces therapeutic radiation, and the imaging system includes one or more independent x-ray imaging sources (each of which may be, for example, a kV source) that produce lower energy imaging radiation. The images under treatment may include one or more (preferably, at least two) two-dimensional images (usually x-rays) (e.g., stereoscopic x-ray images) acquired at one or more different viewpoints of view, and may be compared, for example, with two-dimensional DRRs derived from three-dimensional pre-treatment image information. The DRRs are synthetic x-ray images generated by projecting hypothetical x-rays through 3D imaging data, wherein the direction and orientation of the hypothetical x-rays simulate the geometry of the x-ray imaging system under treatment. The resulting DRRs then have nearly the same scale and viewpoint as the x-ray imaging system under treatment, and may be compared with the x-ray images under treatment to determine the location and orientation of the target, which may then be used to guide the administration of radiation to the target.

[0009] In another common scenario, a gantry-mounted therapeutic radiation source or a separate x-ray imaging source (e.g., a kV source) is used to acquire multiple views and reconstruct a volumetric image - a CT image. Views (also called projections) are acquired for at least 180 degrees plus the imaging beam fan angle to provide full mathematical support for reconstructing a 3D volume or individual axial slices. The imaging detector mounted opposite the x-ray source can be a single-row detector for acquiring data for a single slice at a time, or a multi-row detector or a full two-dimensional flat panel detector for acquiring data for multiple slices at a time.

[0010] There are generally two overall goals in radiation therapy: (i) deliver a highly conformal dose distribution to the target volume (by using CT imaging to conform the radiation delivery / dose to the shape of the target; sparing normal tissue as much as possible); and (ii) deliver the radiation beam with high accuracy throughout each treatment fraction. A third goal may be to accomplish both overall goals in as little time per fraction as possible. Administering a more conformal dose distribution may require, for example, the ability to irradiate non-coplanar beams. Administering treatment beams more accurately may require the ability to track the position of the target volume within the treatment fraction. The ability to increase the speed of delivery requires the ability to move the radiation source accurately, precisely, and quickly without striking other objects in the room or the patient and / or violating speed limits imposed by regulatory agencies.

[0011] Ring-gantry based systems exhibit relatively high mechanical stability and can repeatedly and accurately position a radiation source, including at relatively high mechanical drive speeds, thereby avoiding certain limitations exhibited by robotic arm and / or C-arm gantry based systems.

[0012] With respect to imaging during treatment, x-ray tomosynthesis has been proposed as a kV imaging mode during treatment used in conjunction with a radiotherapy system. X-ray tomosynthesis refers to the process of acquiring a corresponding number of two-dimensional x-ray projection images of a target volume using x-rays incident on the target volume at many different angles, and then mathematically processing the two-dimensional x-ray projection images to produce a set of one or more tomosynthesis reconstruction images representing one or more corresponding slices of the target volume, wherein the number of x-ray projection images is less than the number of reconstructed images in the set required for CT image reconstruction, and / or the number or range of incident radiation angles is less than the number or range of angles used in the CT imaging process. Typically, multiple tomosynthesis reconstruction images are generated, each tomosynthesis reconstruction image representing a different slice of the target volume, and thus sometimes the set of tomosynthesis reconstruction images is referred to as a tomosynthesis volume. As used herein, the term tomosynthesis projection image refers to one of the two-dimensional x-ray projection images acquired during the tomosynthesis imaging process.

[0013] For purposes of the above terminology, for some preferred embodiments, the set of images required for CT image reconstruction is considered to include images (e.g., 300 or more) generated over a range of source angles of at least 180 degrees plus the fan beam angle. For some preferred embodiments, the x-ray projection images used to construct the tomosynthesis image are acquired over an angular range between 1 degree and an angular range value less than the angular range value required for the complete set of projections for CT imaging (e.g., 180 degrees plus the fan angle), wherein the number of projection images generated within this angular range is a value between 2 and 1000. In other preferred embodiments, the x-ray projection images used to construct the tomosynthesis image are acquired over an angular range between 5 degrees and 45 degrees, wherein the number of projection images generated within this range is between 5 and 100.

[0014] U.S. Patent No. 6,778,850, which is incorporated herein by reference, discloses the use of tomosynthesis images as a kV imaging modality in therapy (more specifically, using relatively low-resolution intra-process 3D images of a target region synthesized from multiple two-dimensional diagnostic images acquired at different angles).

[0015] CBCT has also been proposed as an imaging modality in treatment for use in conjunction with a radiation therapy system, in some cases as a kV imaging mode and in other cases as an MV (port) imaging mode. Whereas conventional CT imaging reconstructs 2D slices through a target volume from a 1D projection map and then stacks the 2D slices to form a 3D volumetric image, CBCT imaging constructs a 3D volumetric image directly from the 2D projection map of the target volume. CBCT provides the ability to form a 3D image volume from a single gantry rotation around the target volume (more specifically, at least 180 degrees plus a rotation of the fan beam angle), whereas conventional CT requires more rotations to form the same image volume, including, for example, one rotation per slice (for a single-row detector) or 1 / M rotations per slice (for a quasi-linear multi-row detector with M rows). CBCT also provides more isotropic spatial resolution, whereas conventional CT limits the spatial resolution in the longitudinal direction to the slice thickness. However, since conventional CT systems typically provide much higher collimation near their linear or quasi-linear row detectors than CBCT systems can typically provide near their two-dimensional detectors, scatter noise and artifacts are more problematic for CBCT systems than for conventional CT systems. In addition, a major problem with single-rotation CBCT (besides scatter) is the inadequate sampling on all slices except the central slice (the one containing the rotation).

[0016] Prior to treatment, planning images may be acquired for treatment planning. Subsequently, prior to each treatment fractionation, a CBCT image may be acquired and compared with the pre-treatment planning image, and the results of the comparison are used to modify the treatment plan for that treatment fractionation, for example to compensate for interfraction setup errors and / or interfraction organ motion. Due to the limitation of the allowed C-arm gantry rotation speed (e.g., one rotation per minute), which results in a CBCT acquisition time that is slower than the patient's respiration (or other physiological cycle), a gating scheme synchronized with the patient's respiration (or other physiological cycle) may be used during CBCT acquisition to reduce the deleterious effects of organ motion in the reconstructed image. Moreover, due to the relatively slow CBCT acquisition time, CBCT volume data is typically only useful for patient setup prior to each radiotherapy fractionation, and is not useful for motion correction within the fractionated treatment.

[0017] US Patent No. 9,687,200 (which is incorporated herein by reference) discloses a translatable annular gantry for radiation therapy. An IGRT apparatus is provided, which includes an annular gantry having a central opening and a radiation therapy head coupled to the annular gantry, the radiation therapy head being rotatable about the central opening through an arc of at least 180 degrees.

[0018] One or more problems have been raised with known medical imaging and / or radiation therapy systems, which are at least partially addressed by one or more embodiments further described below, such as improving the accuracy of spatial registration between corresponding image sets to allow more accurate radiation therapy delivery, reducing image artifacts (e.g., scatter, metal and beam hardening, image blur, motion, etc.), and utilizing dual energy imaging (e.g., for material separation and quantitative imaging, patient setup, online adaptive IGRT, etc.). Summary of the invention

[0019] In one embodiment, a multi-modal imaging device includes: a rotatable gantry system positioned to at least partially surround a patient support; a first radiation source coupled to the rotatable gantry system, the first radiation source configured for imaging radiation; a second radiation source coupled to the rotatable gantry system, the second radiation source configured for at least one of imaging radiation or therapeutic radiation, wherein the second radiation source has an energy level exceeding that of the first radiation source; and a first radiation detector coupled to the rotatable gantry system and positioned to receive radiation from at least one of the first radiation source or the second radiation source; wherein first measured projection data from the first radiation source has greater attenuation than second measured projection data from the second radiation source, and wherein a first attenuation estimate associated with the first measured projection data is based on the second measured projection data.

[0020] Features described and / or illustrated with respect to one embodiment may be used in the same manner or in a similar manner in one or more other embodiments and / or in combination with or in place of features of other embodiments.

[0021] The description of the invention does not limit the terms used in the claims or the scope of the claims or the invention in any way. The terms used in the claims have their full ordinary meanings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In the accompanying drawings, embodiments of the present invention are shown, and the accompanying drawings are incorporated into and constitute a part of the specification, and the accompanying drawings are used to illustrate embodiments of the present invention together with the general description of the present invention given above and the detailed description given below. It should be understood that the element boundaries (e.g., boxes, groups of boxes or other shapes) shown in the figures represent an embodiment of the boundaries. In certain embodiments, an element can be designed as a plurality of elements, or a plurality of elements can be designed as an element. In certain embodiments, an element shown as an internal component of another element can be implemented as an external component, and vice versa. In addition, the elements may not be drawn to scale.

[0023] Figure 1 is a perspective view of an exemplary multi-mode radiation therapy apparatus according to one aspect of the disclosed technology.

[0024] Figure 2 is a schematic diagram of an exemplary multi-mode radiation therapy apparatus according to one aspect of the disclosed technology.

[0025] Figure 3 An exemplary radiation therapy environment is shown.

[0026] Figure 4 A diagram of an exemplary multi-mode scanning configuration is shown.

[0027] Figure 5 A diagram of another exemplary multi-mode scanning configuration is shown.

[0028] Figure 6 A diagram showing exemplary modes of a multi-mode scanning configuration is shown in an overlay view.

[0029] Figure 7 Shows Figure 6 Illustration of an enlarged portion of the target shown in .

[0030] Figure 8 is a flow chart depicting an exemplary method of combining scan data from multiple radiation modalities.

[0031] Fig. 9is a flow chart depicting an exemplary method of combining scan data from multiple radiation modes for scatter correction.

[0032] Fig.10 is a flow chart depicting an exemplary method of combining scan data from multiple radiation modalities to reduce metal and beam hardening artifacts.

[0033] Fig.11 is a flow chart depicting an exemplary method of combining scan data from multiple radiation modalities for temporal resolution correction.

[0034] Fig.12 is a flow chart depicting an exemplary method of combining scan data from multiple radiation modalities for motion artifact correction.

[0035] Fig.13 is a flow chart depicting an exemplary method of combining scan data from multiple radiation modalities for material separation and / or quantitative imaging.

[0036] Fig.14 is a flow chart depicting an exemplary method of combining scan data from multiple radiation modalities for patient setup.

[0037] Fig.15 is a flow chart depicting an exemplary method of combining scan data from multiple radiation modalities to perform online adaptive IGRT.

[0038] Fig.16 is a flow chart depicting an exemplary method of IGRT using a radiation therapy device.

[0039] Fig.17 is a block diagram depicting exemplary image-based pre-irradiation steps / options.

[0040] Fig.18 is a block diagram depicting exemplary data sources that may be used during imaging and / or subsequent image-based pre-irradiation steps.

[0041] Fig.19 is a flow chart depicting an exemplary method of using a radiation therapy apparatus including patient setup or alignment.

[0042] Fig. 20 is a flow chart depicting an exemplary method of using a radiation therapy apparatus including adaptive IGRT. DETAILED DESCRIPTION

[0043] The following includes definitions of exemplary terms that may be used throughout the disclosure. All terms in the singular and plural are included within each meaning.

[0044] As used herein, a "component" may be defined as a part of hardware, a part of software, or a combination thereof. A part of hardware may include at least a processor and a part of memory, wherein the memory includes instructions to be executed. A component may be associated with a device.

[0045] As used herein, "logic," which is synonymous with "circuitry," includes, but is not limited to, hardware, firmware, software, and / or a combination of each to perform a function or action. For example, based on the desired application or requirements, logic may include a software-controlled microprocessor, discrete logic such as an application-specific integrated circuit (ASIC), or other programmed logic devices and / or controllers. Logic may also be fully embodied as software.

[0046] As used herein, "processor" includes, but is not limited to, one or more of virtually any number of processor systems or independent processors, for example, a microprocessor, a microcontroller, a central processing unit (CPU), and a digital signal processor (DSP) in any combination. The processor may be associated with various other circuits that support the operation of the processor, such as a random access memory (RAM), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), a clock, a decoder, a memory controller, or an interrupt controller, etc. These support circuits may be inside or outside the processor or its associated electronic package. The support circuits are operatively in communication with the processor. The support circuits need not be shown separately from the processor in a block diagram or other accompanying drawings.

[0047] 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 bit streams, etc.

[0048] 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 behave in a desired manner. Instructions may be embodied in various forms, such as routines, algorithms, modules, or programs, including separate applications or code from dynamically linked sources or libraries.

[0049] Notwithstanding the foregoing exemplary definitions, it is Applicant's intention that these and other terms be accorded the broadest reasonable interpretation consistent with this specification.

[0050] As discussed in more detail below, embodiments of the disclosed technology relate to multi-modal imaging / radiotherapy apparatus and methods. In some embodiments, the radiotherapy irradiation apparatus and method can be used in combination with IGRT or as part of IGRT using an integrated low-energy radiation source for imaging and a high-energy radiation source for imaging and / or treatment. In particular, for example, the radiotherapy irradiation apparatus and method can combine a low-energy collimated radiation source for imaging in a gantry using image acquisition with rotation (e.g., spiral or step-by-step shooting), and a high-energy radiation source for imaging and / or therapeutic treatment. Complementary information and advantages from low-energy radiation sources (e.g., kV) and high-energy radiation sources (e.g., MV) can be utilized. For example, at low energy, the inherent contrast of soft tissue may be higher, while at high energy, there is no shortage of primary photons passing through wide or dense structures. KV and MV imaging data can be used to complement each other to produce higher quality images. High-quality volume imaging may be required for visualization of target objects and organs at risk (OARS), adaptive therapy monitoring, and treatment planning / replanning. In some embodiments, the multi-modal system may also be used for positioning, motion tracking, and / or characterization or correction capabilities.

[0051] The image acquisition method may include or otherwise utilize multiple rotational scans, which may be, for example, a continuous scan (e.g., with a helical source trajectory about a central axis and longitudinal movement of a patient support through a gantry aperture), a non-continuous circular stop-return scan with incremental longitudinal movement of a patient support, a step-and-shoot annular scan, etc.

[0052] According to various embodiments, the multi-mode device uses, for example, a beam shaper (which may include a collimator) to limit the beam to collimate the radiation source, including, for example, into a cone beam or a fan beam. In one embodiment, the collimated beam can be combined with a gantry that continuously rotates while the patient moves, thereby producing a spiral image acquisition.

[0053] In some embodiments, the time associated with increased scanning rotation to complete 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 rpm (rpm refers to revolutions per minute), up to 20 rpm, up to 60 rpm or more), high frame rates and / or sparse data reconstruction techniques to provide CT quality imaging on a radiation therapy delivery platform. Detectors (with various row / slice sizes, configurations, dynamic ranges, etc.), scan spacing and / or dynamic collimation are additional features in various embodiments, including for selectively exposing portions of the detector and selectively defining an effective read zone.

[0054] Multi-mode 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). Moreover, exposing only a primary area of ​​the detector to direct radiation can allow a shadowed area of ​​the detector to receive only scatter. In some embodiments, scatter measurements in the shadowed area of ​​the detector (and in some embodiments, measurements in the penumbra area) can be used to estimate scatter in the primary area of ​​the detector that receives projection data.

[0055] Multi-mode devices and methods can provide selective and variable detector read zones and ranges, including adjusting the detector read range to limit the active area of ​​the detector to increase read speed. For example, less than available shadow area data can be read and used for scatter estimation. Combining selective readout with beamforming allows for various optimizations of scatter fitting techniques.

[0056] refer to Figure 1 and Figure 2 , showing a multi-mode device 10. It should be understood that the multi-mode device 10 can be used with a radiation therapy device (such as Figure 2 ) is associated with and / or integrated into a radiation therapy device, which can be used for a variety of applications, including but not limited to IGRT, such as as an IGRT irradiation system (e.g., Figure 3IGRT delivery system 104 shown in and discussed in detail below). The multi-modal device 10 includes a rotatable gantry system, referred to as a gantry 12, which is supported by or otherwise contained in a support unit or housing 14. A gantry herein refers to a gantry system that includes one or more gantries (e.g., ring or C-arms) that are capable of supporting one or more radiation sources and / or associated detectors as they rotate around a target object. For example, in one embodiment, a first radiation source and its associated detector may be mounted to a first gantry of the gantry system, and a second radiation source and its associated detector may be mounted to a second gantry of the gantry system. In another embodiment, more than one radiation source and associated (one or more) detectors may be mounted to the same gantry of the gantry system, including, for example, where the gantry system consists of only one gantry. Various combinations of gantries, radiation sources, and radiation detectors may 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 a MV radiation source can be mounted on the same or different gantries of a gantry system and selectively used for imaging and / or treatment as part of an IGRT system. If mounted to different gantries, the radiation sources can rotate independently but still be able to image the same (or nearly the same) volume at the same time. As described above, the rotatable annular gantry 12 can be capable of 10 rpm or more. The rotatable gantry 12 defines a gantry aperture 16 into which a patient can be moved and 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 the radiation source and associated (one or more) 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. This configuration allows for continuous spiral computed tomography, including CBCT, even when integrated into an IGRT system. As mentioned above, the main problem of single rotation CBCT is that all slices except the central slice (the slice containing the rotation) are undersampled. This can be overcome by spiral trajectory cone beam imaging.

[0057] The patient support 18 is positioned adjacent to the rotatable gantry 12 and is configured to support the patient in a generally horizontal position for longitudinal movement into and inside 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 the 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 around the longitudinal axis of the patient according to the commanded imaging and / or treatment plan. Once the patient support is located 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, wherein, from the front of the gantry 12, the x-axis is horizontal and points to the right, the y-axis points in 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.

[0058] like Figure 2 As shown, the multi-mode device 10 includes a low energy radiation source (e.g., kV) 30, which is coupled to the rotatable gantry 12 or otherwise supported by the rotatable gantry 12. In this embodiment, the low energy radiation source 30 is a source of imaging radiation and emits a radiation beam (generally indicated as 32) for generating high quality images. In this embodiment, the source of imaging radiation is an x-ray source 30, which is configured as a kilovolt (kV) source (e.g., a clinical x-ray source with an energy level in the range of about 20 kV to about 150 kV). In one embodiment, the low energy radiation source includes a kiloelectron volt 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 x-ray generating sources for CT) or any other means of generating photons with sufficient energy and flux (e.g., a gamma source (e.g., cobalt 57, with an energy peak at 122 keV), an x-ray fluorescence source (e.g., a fluorescence source via Pb k-line, with two peaks at @ about 70 keV and @ about 82 keV), etc.). References herein to x-rays, x-ray imaging, x-ray imaging sources, etc. are exemplary for specific embodiments. In various other embodiments, other imaging transmission sources may be used interchangeably. An x-ray detector 34 (e.g., a two-dimensional flat panel detector or a curved detector) may be coupled to or otherwise supported by the rotatable gantry 12. The x-ray detector 34 is positioned to receive radiation from the x-ray source 30 and may rotate with the x-ray source 30.

[0059] It should be understood that the x-ray detector 34 may take on a variety of configurations without departing from the scope of the disclosed technology. Figure 2As shown, the x-ray detector 34 can be configured as a flat panel detector (e.g., a multi-row flat panel detector). According to another exemplary embodiment, the x-ray detector 34 can be configured as a curved detector. The detector 34 can detect or otherwise measure the amount of unattenuated radiation and thus infer the amount of radiation that is actually attenuated by the patient or associated patient ROI (compared to the amount of radiation originally generated). As the low-energy radiation source 30 rotates around the patient and emits radiation toward the patient, the detector 34 can detect or otherwise collect attenuation data from different angles.

[0060] although Figure 1 and Figure 2 A multi-mode device 10 is depicted with a radiation source 30 mounted to an annular gantry 12, but other embodiments may include other types of rotatable imaging devices, including, for example, C-arm gantry-based systems and robotic arm-based systems. In a gantry-based system, the gantry rotates the imaging radiation source 30 about an axis passing through the isocenter. A gantry-based system includes a C-arm gantry in which the imaging radiation source 30 is mounted in a cantilevered manner above and rotates about an axis passing through the isocenter. A gantry-based system also includes an annular gantry, such as a rotatable gantry 12, which has a generally annular shape in which the patient's body extends through a hole of the annulus / annulus, and the imaging radiation source 30 is mounted on the circumference of the annulus and rotates about an axis passing through the isocenter. In some embodiments, the gantry 12 rotates continuously. In other embodiments, the gantry 12 utilizes a cable-based system that repeatedly rotates and reverses.

[0061] A collimator or beam shaper assembly (generally indicated as 36) is positioned relative to the 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 an area of ​​the active area of ​​the x-ray detector 34. The beam shaper can also control how the radiation beam 32 is positioned on the x-ray 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 rectangles of various sizes). In other embodiments, the beam shaper 36 can have various other dynamically controlled shapes, including, for example, a parallelogram. 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 / or translated.

[0062] The beam shaper 36 can be controlled to dynamically adjust the shape of the radiation beam 32 emitted by the x-ray source 30 according to many geometries, including but not limited to fan beams or cone beams, having a beam thickness (width) as low as one detector row width or including multiple detector rows, which may be only a portion of the active area of ​​the detector. In various embodiments, the thickness of the beam can expose a larger detector active area of ​​several centimeters. For example, 3-4 centimeters (measured in the longitudinal direction in the plane of the detector) of a 5-6 cm detector can be selectively exposed to imaging radiation 32. In this embodiment, 3-4 centimeters of projection image data can be captured at each readout, with approximately 1-2 centimeters of unexposed detector area on one or each side, which can be used to capture scattered data, as described below.

[0063] In other embodiments, more or less of the effective 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 sizes, including using smaller detectors. In other embodiments, the beam thickness can be increased to a range of about 4 centimeters, 5 centimeters, greater than 5 centimeters, or similar sizes, including using larger detectors. In various embodiments, the ratio of exposed-to-active detector area to effective detector area can be 30-90% or 50-75%. In other embodiments, the ratio of exposed-to-active detector area to effective detector area can be 60-70%. However, in other embodiments, various other exposed area sizes and effective area sizes or ratios of exposed detector area to effective detector area may be suitable. The beam and detector can be configured so that the shadow area of ​​the detector (effective but not exposed to direct radiation) is sufficient to capture scattered data outside the penumbra area.

[0064] Various embodiments may include optimization of features that control selective exposure of the detector (e.g., beam size, beam / aperture center, collimation, spacing, detector read range, detector read center, etc.) so that the measured data is adequate for both the primary (exposed) area and the shadow area, but is also optimized for speed and dose control. The shape / position of the beam shaper 36 and the read range of the detector 34 may be controlled so that the radiation beam 32 from the x-ray source 30 covers as much or as little of the x-ray detector 34 as possible based on the specific imaging task and scatter estimation process being performed, for example, including a combination of narrow and wide axial field of view (aFOV) scans. The device 10 has the ability to acquire a single rotation cone beam as well as wide and narrow beam angle images, spiral images, or other images.

[0065] The beam shaper 36 may be configured in a variety of ways to allow it to adjust the shape of the radiation beam 32 emitted by the x-ray source 30. For example, the beam shaper 36 may be configured to include a set of jaws or other suitable components that define and selectively adjust the size of an aperture through which the radiation beam from the x-ray source 30 may pass in a collimated manner. According to one exemplary configuration, the beam shaper 36 may include an upper jaw and a lower jaw, wherein the upper jaw and the lower jaw may be moved 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 adjust the position of the beam 32 relative to the patient to irradiate only the portion of the patient to be imaged, thereby optimizing imaging and minimizing patient dose.

[0066] 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 an exemplary implementation, the blade position and / or aperture width of the beam shaper 36 can be adjusted before or during a scan. For example, according to one embodiment, the beam shaper 36 can be selectively controlled and dynamically adjusted during the rotation of the x-ray source 30 so that the shape of the radiation beam 32 has sufficient primary / shadow areas and is adjusted to include only the object of interest during imaging (e.g., the prostate). The shape of the radiation beam 32 emitted by the x-ray source 30 can be changed during or after a scan based on the desired image acquisition, which can be based on imaging and / or therapy feedback, as discussed in more detail below.

[0067] like Figure 2 As shown, the multi-mode device 10 can be integrated with a radiotherapy device including a high energy radiation source (e.g., MV) 20, which is coupled to the rotatable gantry 12 or otherwise supported by the rotatable gantry 12. According to one embodiment, the high energy radiation source 20 is configured as a source of therapeutic radiation, for example, a high energy radiation source for treating a tumor in a patient's body in a region of interest. In other embodiments, the high energy radiation source 20 is also configured as a source of imaging radiation, or at least utilized as such. It will be understood that the source of therapeutic radiation can be a high energy x-ray beam (e.g., a 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. In one embodiment, the high energy radiation source 20 includes a mega-electron volt peak photon energy (MeV) of 1 MeV or greater. 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. Typically, the high energy radiation source 20 has a higher energy level (peak and / or average, etc.) than the low energy radiation source 30 .

[0068] In one embodiment, the high energy radiation source 20 is a LINAC that produces therapeutic radiation (e.g., MV), and the imaging system includes a separate low energy radiation source 30 that produces relatively low intensity and lower energy imaging radiation (e.g., kV). In other embodiments, the therapeutic radiation source 20 can be a radioisotope, such as cobalt-60, which can generally have an energy greater than 1 MeV. The high energy radiation source 20 can emit one or more radiation beams (generally represented by 22) to a region of interest (ROI) within a patient supported on a patient support 18 according to a treatment plan.

[0069] In various embodiments, the high energy radiation source 20 is utilized as a source of therapeutic radiation and a source of imaging radiation. As discussed in detail below, the radiation sources 20, 30 can be used in conjunction with each other to provide higher quality and better utilized images. References to the therapeutic radiation source 20 herein are intended to distinguish the high energy radiation source 20 from the low energy radiation source 30, which can be used only for imaging. However, references to the therapeutic radiation source 20 include embodiments in which the therapeutic radiation source 20 (high energy radiation source) can be used for treatment and / or imaging. 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 the peak photon energy of the radiation sources 20, 30.

[0070] Detector 24 may be coupled to or otherwise supported by rotatable gantry 12 and positioned to receive radiation 22 from therapeutic radiation source 20. Detector 24 may detect or otherwise measure the amount of unattenuated radiation and therefore infer the amount of radiation that is actually attenuated by the patient or associated patient ROI (as compared to the amount of radiation originally generated). Detector 24 may detect or otherwise collect attenuation data from different angles as therapeutic radiation source 20 rotates around and emits radiation toward the patient.

[0071] It will be further understood that the therapeutic radiation source 20 may include or be otherwise associated with a beam shaper or collimator. The beam shaper associated with the therapeutic radiation source 20 may be configured in a variety of ways, similar to the beam shaper 36 associated with the imaging source 30. For example, the beam shaper may be configured as a multi-leaf collimator (MLC), which may include a plurality of staggered leaves that are operable to move to one or more positions between a minimum open or closed position and a maximum open position. It should be understood that the leaves may 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 achieving sub-millimeter aiming accuracy.

[0072] Therapeutic radiation source 20 may be mounted, configured and / or moved into the same plane or a different plane (offset) as imaging source 30. In some embodiments, scatter caused by simultaneous activation of radiation sources 20, 30 may be reduced by offsetting the radiation planes.

[0073] In other embodiments, scatter can be avoided by staggered activation. For example, in the case of simultaneous multi-modality imaging, acquisitions can be concurrent without concurrent individual pulses. In another embodiment, the use of shadow-based scatter correction can be used to, for example, address the problem of MV scatter on kV detectors.

[0074] When integrated with a radiation therapy device, the multi-modal device 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 setup is accomplished by comparing the current (treatment) image with pre-treatment image information. The pre-treatment image information may include, for example, CT data, cone beam CT data, MRI data, PET data, or 3D rotational angiography (3DRA) data and / or any information obtained from these or other imaging modalities. In some embodiments, the multi-modal device 10 can track the motion of a patient, target object, or ROI during treatment.

[0075] The reconstruction processor 40 may be operably coupled to the detector 24 and / or the detector 34. In one embodiment, the reconstruction processor 40 is configured to generate a patient image based on the radiation received by the detectors 24, 34 from the radiation sources 20, 30. It should be understood that the reconstruction processor 40 may be configured to perform the methods described more fully below. The device 10 may 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 acquired images (e.g., planning images), treatment plans, etc.

[0076] The multi-modal device 10 may include an operator / user interface 48 at which an operator of the device 10 may interact with or otherwise control the device 10 to provide input related to scanning or imaging parameters, etc. The operator interface 48 may include any suitable input device, such as a keyboard, a mouse, a voice-activated controller, etc. The device 10 may also include a display 52 or other human-readable element for providing output to an operator of the device 10. For example, the display 52 may allow the operator to observe reconstructed patient images and other information, such as imaging or scanning parameters related to the operation of the device 10.

[0077] like Figure 2As shown, the multi-mode device 10 includes a controller (generally indicated as 60) that is operably coupled to one or more components of the device 10. The controller 60 controls the overall operation and operation of the device 10, including providing power and timing signals to the x-ray source 30 and / or the therapeutic radiation source 20 and the gantry motor controller that controls the rotation speed and position of the rotatable gantry 12. It should be understood that the controller 60 can include one or more of the following: a patient support controller, a gantry controller, a controller coupled to the therapeutic radiation source 20 and / or the x-ray source 30, a beam shaper controller, a controller coupled to the detector 24 and / or the x-ray detector 34, etc. In one embodiment, the controller 60 is a system controller that can control other components, devices, and / or controllers.

[0078] In various embodiments, the reconstruction processor 40, operator interface 48, display 52, controller 60, and / or other components may be combined into one or more components or devices.

[0079] The device 10 may include various components, logic and software. In one embodiment, the controller 60 includes a processor, memory and software. By way of example and not limitation, the multi-mode device and / or radiotherapy system may include various other devices and components (e.g., gantry, radiation source, collimator, detector, controller, power supply, patient support, etc.), which may implement one or more routines or steps related to imaging and / or IGRT for a specific application, wherein the routine may include imaging, image-based pre-irradiation steps and / or radiotherapy irradiation, including corresponding device settings, configurations and / or positions (e.g., paths / trajectories) that may be stored in memory. In addition, the controller may directly or indirectly control one or more devices and / or components according to one or more routines or processes stored in 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 the communication of position, path, speed, etc. to a patient support controller or other peripheral device. The hierarchy of various controllers that may be associated with a device may be arranged in any suitable manner to communicate appropriate commands and / or information to the desired devices and components.

[0080] In addition, it will be appreciated by those skilled in the art that other computer system configurations may be utilized to implement the system and method. The illustrated aspects of the present invention may be practiced in a distributed computing environment where certain tasks are performed by local or remote processing devices linked via a communications network. For example, in one embodiment, the reconstruction processor 40 may be associated with a separate system. In a distributed computing environment, program modules may be located in local and remote storage devices. For example, a remote database, a local database, a cloud computing platform, a cloud database, or a combination thereof may be used together with the device 10.

[0081] The multi-modal device 10 can implement various aspects of the present invention using an exemplary environment that includes 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 a read-only memory (ROM), a random access memory (RAM), a hard drive, a flash drive, 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.

[0082] The therapeutic radiation source 20 and / or the x-ray source 30 may be operably coupled to a controller 60 configured to control the relative operation of the therapeutic radiation source 20 and the x-ray source 30. For example, the x-ray source 30 may be controlled and may be operated simultaneously with the therapeutic radiation source 20. Additionally or alternatively, depending on the particular treatment and / or imaging plan being implemented, the x-ray source 30 may be controlled and may be operated sequentially with the therapeutic radiation source 20. For example, in various embodiments, the radiation sources 20, 30 may be operated such that the measured projection data from the radiation sources 20, 30 are acquired simultaneously (or substantially / nearly (quasi) simultaneously, e.g., within about 50 milliseconds of each other) or sequentially (e.g., separated by seconds, minutes, etc.).

[0083] It will be appreciated that the radiation sources 20, 30 and detectors 24, 34 may be configured to provide rotation about the patient during imaging and / or therapy scans in a variety of ways. In one embodiment, synchronizing the movement and exposure of the sources 20, 30 with the longitudinal movement of the patient support 18 may provide continuous spiral acquisition or scanning of patient images during surgery. In addition to continuous rotation of the radiation sources 20, 30 and detectors 24, 34 (e.g., the gantry continuously and constantly rotates at a constant patient movement speed), it will be appreciated that other variations may be employed without departing from the scope of the disclosed technology. For example, the rotatable gantry 12 and patient support may be controlled such that the gantry 12 rotates about a patient supported on the patient support in a "back and forth" manner (e.g., alternately rotating clockwise and counterclockwise) when the support is controlled to move (at a constant or variable speed) relative to the rotatable gantry 12 (as opposed to a continuous manner as described above). In another embodiment, in the case of a continuous step-and-shoot annular scan, movement of the patient support 18 in the longitudinal direction (stepping) is alternated with scanning revolutions (shooting) through the rotatable gantry 12 until the desired volume is captured. The multi-modal device 10 is capable of both volume-based and planar-based imaging acquisitions. For example, in various embodiments, the multi-modal device 10 can be used to acquire volumetric images and / or planar images and perform associated processing, including the scatter estimation / correction methods described below.

[0084] Various other types of radiation source and / or patient support movement may be utilized to achieve relative motion of the radiation source and the patient to generate projection data. Discontinuous motion of the radiation source and / or patient support, continuous but variable / non-constant (including linear and non-linear) movement, speed and / or trajectory, etc., and combinations thereof may be used, including in conjunction with various embodiments of the apparatus 10 described above.

[0085] In one embodiment, the rotation speed of the gantry 12, the speed of the patient support 18, the shape of the beam shaper and / or the reading of the detector can all be kept constant during image acquisition. In other embodiments, one or more of these variables can be dynamically changed during image acquisition and / or treatment.

[0086] In other embodiments, these features may be combined with one or more other image-based activities or procedures, including, for example, patient setup, adaptive therapy monitoring, treatment planning, and the like.

[0087] Figure 3 An exemplary radiation therapy environment 300 is shown. The radiation therapy environment 300 includes a reference imaging system 102 and an IGRT system 104. The IGRT system 104 may include, for example, the multi-modality apparatus 10 and its various components and devices as described above.

[0088] In one embodiment, the reference imaging system 102 may include a high-precision volumetric imaging system, such as, for example, a system such as a CT system or an MRI system. Given cost and workflow considerations in many clinical settings, the reference imaging system 102 is typically a general-purpose tool used for a variety of different purposes in a clinic or hospital setting and is not specifically specific to the IGRT system 104 or environment 300. Rather, the reference imaging system 102 may be located in its own separate room or vault and purchased, installed, and / or maintained on a separate and more general basis than the IGRT system 104. Thus, for Figure 3 In some embodiments, the reference imaging system 102 is shown as distinct from the IGRT system 104. In other embodiments, the reference imaging system 102 may be considered an integral component of the IGRT system 104. For example, the multi-modality device 10 has the ability to function as both the reference imaging system 102 and the IGRT system 104.

[0089] In this embodiment, the IGRT system 104 includes a high energy radiotherapy (MV) source 108 that selectively applies high energy x-ray therapeutic radiation to a target volume of a patient P positioned on a patient support or treatment couch TC. The MV source 108 applies therapeutic radiation under the control of a system controller 114 (more specifically, a therapeutic radiation control subsystem 128 in one embodiment). The system controller 114 also includes a processing circuit 120, a detector controller 122, a couch position controller 124, and a kV radiation controller 126, each of which is programmed and configured to implement one or more functions further described herein. One or more imaging (kV) radiation sources 110 selectively emit relatively low energy x-ray imaging radiation under the control of the kV radiation controller 126, which is captured by one or more detectors 112. The one or more detectors 112 can capture high energy x-ray therapeutic radiation from the MV source 108 that has propagated through the target volume.

[0090] Each of the kV radiation source 110 and the MV radiation source 108 has a precisely measurable and / or precisely determinable geometry relative to the (x, y, z) coordinate system of the IGRT system 104 and / or the treatment room because they are dynamically movable.

[0091] The bed positioner 130 can be actuated by the bed position controller 124 to locate the position of the bed TC. In some embodiments, the non-x-ray based position sensing system 134 uses one or more methods that do not involve ionizing radiation (e.g., optical or ultrasound based methods) to sense the position and / or movement of (one or more) external markers strategically attached to the patient, and / or sense the position and / or movement of the patient's skin surface itself. The IGRT system 104 also includes an operator workstation 116 and a treatment planning system 118.

[0092] In typical clinical practice, treatment planning is performed on a pre-acquisition treatment planning image or previous image data 106 generated by a reference imaging system 102. The pre-acquisition treatment planning image 106 is typically a high-resolution three-dimensional CT image that is acquired substantially prior to (e.g., one to two days in advance) one or more radiation therapy fractions that the patient will undergo. Figure 3 As indicated by the illustration of the (i, j, k) coordinate system for the treatment planning image 106 prior to acquisition (which is different from the (x, y, z) treatment room coordinate system shown for the treatment room of the IGRT system 104), there is typically no pre-existing or inherent alignment or registration between the treatment planning image 106 coordinate system and the treatment room coordinate system. During the treatment planning process, the physician typically establishes a coordinate system within the treatment planning image (e.g., i, j, k in the treatment planning image 106), which may also be referred to herein as the planning image coordinate system or planning image reference system. The radiation therapy plan is formulated in the planning image coordinate system, which specifies the various orientations, sizes, durations, etc. of the high energy therapeutic radiation beams applied by the MV source 108 during each treatment fraction. When the entire delivery and tracking system (if present) is calibrated to the treatment room coordinate system, accurately delivering therapeutic radiation to the target requires alignment of the planning image coordinate system with the treatment room coordinate system. It will be appreciated that this alignment need not be exact, and it will also be appreciated that couch adjustments or beam delivery adjustments may be used to account for drift in the alignment between the two coordinate systems.

[0093] In one embodiment, immediately prior to each treatment fractionation, an image-based pre-irradiation step may be performed under image guidance via a kV imaging radiation source 110, including according to one or more embodiments further described below. For example, the patient may be physically positioned or aligned so that the planning image coordinate system (for example and not by way of limitation, defined by the physician while creating the treatment plan on the CT image or planning image) is positioned in an initial alignment with the treatment room coordinate system, hereinafter referred to as the initial treatment alignment or initial treatment position. This alignment is generally referred to as patient setup or patient alignment. Depending on the location of the target volume, the target volume may change in position and orientation and / or experience volume deformation due to movement of the patient and / or physiological cycles such as breathing. As used herein, the term alignment change during treatment or position change during treatment is used to refer to a change in position, orientation, and / or volume shape of the target volume that is different from the initial treatment alignment. With the known relationship between the treatment plan coordinate system and the treatment room coordinate system, the term alignment change during treatment may also be used to refer to a change in position, orientation, or volume shape of the target volume that is different from the current state of the treatment plan coordinate system. More generally, the term initial treatment alignment or initial treatment position refers herein to a particular physical pose or disposition (including position, orientation, and volumetric shape) of a patient's body part in a patient setting at the start of a treatment fraction.

[0094] A non-x-ray based position sensing system 134 may also be provided. The non-x-ray based position sensing system 134 may include, for example, an external marker affixed to the patient's chest in some manner that moves in response to breathing so that the target position can be accurately determined. Other mechanisms for monitoring breathing may also be used. Other non-respiratory position sensing systems 134 may also be used, including, for example, quasi-static positioning, EKG for cardiac gating, and the like. The system 134 may correlate the movement of the external marker with the target movement, such as the target movement determined from, for example, a single x-ray projection or a stereoscopic x-ray projection. Thus, the non-x-ray based position sensing system 134 may allow the system controller 114 to monitor the external marker movement, use the correlation model to accurately predict in real time (e.g., ~60 Hz) where the target will be positioned, and direct the treatment beam to the target. As treatment of the moving target progresses, additional x-ray images may be obtained and used to verify and update the correlation model.

[0095] As used herein, "registration" of medical images refers to determining a mathematical relationship between corresponding anatomical features or other (e.g., reference) features that appear in those medical images. Registration may include, but is not limited to, determining one or more spatial transformations that, when applied to one or both of the medical images, will cause an overlap of corresponding anatomical features. The spatial transformations may include rigid body transformations and / or deformable transformations, and if the medical images are from different coordinate systems or reference systems, the spatial transformations may take into account differences in those coordinate systems or reference systems. For situations where the medical images are not acquired using the same imaging system and are not acquired simultaneously, the registration process may include, but is not limited to, determining a first transformation that may take into account differences between imaging modes, imaging geometries, and / or reference systems of different imaging systems, and determining a second transformation that takes into account potential anatomical differences that may occur in a body part between acquisition times (e.g., positioning differences, overall movement, relative movement between different structures within a body part, overall deformation, local deformation within a body part, etc.).

[0096] Image registration can be achieved between the reference imaging system 102 and the IGRT delivery system 104 and / or between data and / or images derived from various modes of the multi-mode IGRT delivery system 104, including the low energy source(s) 110 and the high energy source(s) 108 (and their associated detectors 112). In particular, returning to the reference device 10, registration can be achieved between data and / or images derived from the radiation sources 20, 30 and the detectors 24, 34.

[0097] In one embodiment, Figure 4 A diagram of an exemplary multi-mode scanning configuration 400 is shown. Looking at the front of the annular gantry 410, Figure 4A high energy radiation source 420 (e.g., MV) and a low energy radiation source 430 (e.g., kV) are shown mounted to an annular gantry 410. The radiation sources 420, 430 are shown mounted orthogonally to one another, but other embodiments may include other angular relationships and additional radiation sources and / or detectors. The high energy radiation source 420 is shown projecting radiation through a beam shaper 426 to produce a radiation beam 422 projected onto a portion of a detector 424. In this configuration, the high energy radiation source 420 has a trans-axial field of view (FOV) 428. The low energy radiation source 430 is shown projecting radiation through a beam shaper 436 to produce a radiation beam 432 projected onto a portion of a detector 434. In this configuration, the low energy radiation source 430 has a trans-axial field of view (FOV) 438. The detector 434 is shown centered within its range 435. In this manner, the radiation sources 420, 430 will project radiation through overlapping trans-axial FOVs. In this embodiment, the multi-mode scanning configuration 400 shows that the high energy FOV 428 has a larger trans-axis FOV compared to the low energy FOV 438.

[0098] In another embodiment, Figure 5 4 shows another exemplary multi-mode scanning configuration 500. Looking at the front of the annular gantry 410, Figure 5 Also shown are a high energy radiation source 420 and a low energy radiation source 430 mounted orthogonally to the annular gantry 410. The high energy radiation source 420 is shown projecting radiation through a beam shaper 526 to produce a radiation beam 522 projected onto a detector 524. In this configuration, the high energy radiation source 420 has a trans-axial FOV 528. The low energy radiation source 430 is shown projecting radiation through a beam shaper 536 to produce a radiation beam 532 projected onto an offset detector 534. In this configuration, the low energy radiation source 430 has a trans-axial FOV 538 with at least 180 degrees of rotation. In this manner, the radiation sources 420, 430 will also project radiation through overlapping trans-axial FOVs. In this embodiment, the multi-mode scanning configuration 500 shows that the low energy FOV 538 has a larger trans-axial FOV than the high energy FOV 528.

[0099] Various factors, including, for example, beam shaper configuration, radiation source angle, detector position, etc., can be used to control the respective FOVs (e.g., transaxial FOV and axial FOV) of the radiation sources. In some embodiments, the radiation sources 420, 430 can be physically offset in the longitudinal direction (along the y-axis) and can scan the patient at different times (temporal offset).

[0100] In another embodiment, Figure 6An illustration of an exemplary mode of a multi-mode scanning configuration 600 is shown by way of an overlay view. Looking at the side of the annular gantry (not shown), Figure 6 The location of a high energy radiation source 620 (e.g., MV) and a low energy radiation source 630 (e.g., kV) are shown superimposed in the same plane of a target 615. The radiation sources 620, 630 are typically not mounted against each other, but may be mounted to the gantry 90 degrees apart, but in Figure 6 634. The detector 634 is shown as being superimposed in order to illustrate an exemplary overlap of their respective views and features. Other embodiments may include other angular relationships and additional radiation sources. The high energy radiation source 620 is shown as projecting radiation through a beam shaper 626 to produce a radiation beam 622 projected onto a detector 624. In this configuration, the high energy radiation source 620 has an axial FOV 628. The low energy radiation source 630 is shown as projecting radiation through a beam shaper 636 to produce a radiation beam 632 projected onto a portion of a detector 634. In this configuration, the low energy radiation source 630 has an axial FOV 638. The detector 634 is shown as having an active area 634a that receives direct projection and a shadow area 634b that is blocked from direct radiation by the beam shaper 636. In this manner, the radiation sources 620, 630 will project radiation through overlapping axial FOVs. In this embodiment, the multi-mode scanning configuration 600 shows a low energy FOV 638 having a larger axial FOV than the high energy FOV 628 .

[0101] Figure 7 Shows Figure 6 700 of the target 615 shown in FIG. 700. The radiation beams 622, 632 are shown passing through the target 615. The high energy FOV 628 and the low energy FOV 638 provide overlapping imaging data. Here, the low energy FOV 638 provides imaging data beyond the high energy FOV 628, as shown in area 740. However, in other embodiments, as described above, the high energy FOV 628 can provide imaging data beyond the low energy FOV 638. In some embodiments, the FOV 628, FOV 638 can be the same (e.g., the same transaxially and / or axially). In other embodiments, the FOV 628, FOV 638 can be adjacent but not overlapping, can have space between them, can be united so that one FOV is within the other FOV without overlapping, etc., as well as combinations thereof.

[0102] In some embodiments, one or more radiation sources may be used for sparse data, utilizing different resolutions, speeds, trajectories, frequencies, power levels, doses, FOVs, etc. In any case, data from two or more radiation modalities may be used in combination to improve image quality, speed, dose, workflow, treatment accuracy / precision, etc.

[0103] In various embodiments, the exemplary scanning configurations 400 , 500 , 600 may be implemented using the multi-modality device 10 , including via the radiation therapy environment 300 .

[0104] The following flow charts and block diagrams illustrate exemplary configurations and methods associated with the above-described multi-mode radiation system. The exemplary methods may be performed in logic, software, hardware, or a combination thereof. In addition, although the procedures and methods are presented in order, the blocks may be performed in a different order, including serially and / or in parallel. Furthermore, additional steps or fewer steps may be used.

[0105] Figure 8 800 is a flowchart depicting an exemplary method 800 for combining scan data from multiple radiation modes (such as those described above). At step 805, previous image data 805 may be provided. At step 810, method 800 determines a scan configuration, including a scan design for each mode of a multi-mode system. Then, at step 820, a scan is performed, including, for example, a low energy kV scan and a high energy MV scan, as described above. The scan produces low energy scan data 830 and high energy scan data 832. Next, at step 840, method 400 utilizes or combines the low energy scan data 830 and the high energy scan data 832. Then at step 850, the method 800 processes the combined data set, for example, to reconstruct an image. In this manner, in general, the scan configuration and the associated scan design can be configured so that at least one of the scan data 830, 832 complements or supplements another of the scan data 830, 832 from different modes to produce at least one of the improvements discussed herein.

[0106] In some embodiments, the scanning configuration includes a spiral scanning trajectory. The spiral fan-beam MV (high energy) CT (MVCT) acquisition geometry can provide several advantages, including, for example, wide lateral views (e.g., about 40 cm at the isocenter), complete Fourier sampling of the volume of interest, and reduced scatter fraction in the projected image. These features can improve the quality of images reconstructed on clinically advanced cone-beam MVCT. In particular, for example, the source of these advantages is the fan-shaped collimated MV treatment / imaging beam, and the fact that the MV source and detector are mounted on a continuously rotating slip ring system capable of imaging from all directions, as described above. In operation, the system (e.g., device 10) can continuously image over 2π radians, thereby moving the source and detector in a spiral trajectory relative to the patient on a translation couch without stopping to unwind cables or relying on atypical imaging trajectories.

[0107] In various embodiments, in addition to the helical fan beam MVCT system, the kV (low energy) x-ray source and flat panel detector allow the system to acquire kV CT (kVCT) images in the following geometries: helical fan beam; helical narrow cone angle cone beam; and fixed bed, circular trajectory fan beam, etc., as described above. Because the kV imaging hardware is mounted on the same slip ring gantry as the MV imaging / therapy hardware (e.g., as described above), the kV imaging hardware is mounted on the same slip ring gantry as the MV imaging / therapy hardware. Figure 2 and 4 -6), so the kV imaging system can also take advantage of the advantages of the slip ring mounted imaging system, as described above, allowing the kV imaging system to be operated as a diagnostic CT rather than as a positioning CBCT as found in traditional C-arm systems.

[0108] Another unique advantage of a multi-modality (e.g., dual kV / MV) slip ring mounted imaging system (e.g., device 10) is that the systems mounted together (e.g., orthogonally to each other) can be used to acquire image data that is completely synchronized in time and space. Both the MV system and the kV system can image the same anatomical structure at the same time, thereby producing a simultaneous acquisition of the patient's anatomical structure (e.g., as Figure 6-7 ), including 3-D information over time. Although the projection angle may be different for each system, this does not pose a problem for complete CT imaging of the object and the inherent symmetry in CT reconstruction. Combined with the fast imaging speed due to the slip ring mounting, the system can quickly acquire high temporal resolution kV / MV fan beam images over a long axial range.

[0109] In various embodiments, the multi-mode apparatus 10 may include an N-tuple source and detector CT system (where N sources and N or other number of detectors are positioned so that their corresponding projection image data can be acquired simultaneously), wherein the sources provide multiple-energized (e.g., low energy and high energy) projection data. The use of a fan beam imaging geometry (e.g., using a spiral scanning trajectory) in conjunction with simultaneous multiple energized kV / MV imaging devices produces the advantages described herein. As described above, typical prior art systems are limited to cone beam imaging geometries for either kV sources or MV sources alone, which have significant disadvantages compared to fan beam imaging geometries.

[0110] In various embodiments, high energy MV fan beam projections and low energy kV fan beam or cone beam projections can be used in simultaneous CT reconstruction. In some embodiments, MV projections can be used as prior information to correct artifacts of kVCT, or used in dual energy CT reconstruction for quantitative imaging and material separation. In addition, MLC modulated MV projection data is available during treatment and can be utilized in kVCT reconstruction simultaneously with or after radiotherapy administration. KV acquisition can be performed simultaneously with and / or prior to treatment. Electron density images obtained from dual energy reconstruction can be used in both online and offline dosimetry applications.

[0111] One or more embodiments described herein at least partially address several problems that arise in known medical imaging and / or radiation therapy systems, such as improving the accuracy of spatial registration between corresponding image sets to allow more accurate radiation therapy delivery, reducing image artifacts (e.g., scatter, metal and beam hardening, image blur, motion, etc.), and utilizing dual energy imaging (e.g., for material separation and quantitative imaging, patient setup, online adaptive IGRT, etc.).

[0112] I A

[0113] In some embodiments, a multi-mode device can be used for scatter correction. Figure 2 In one embodiment of the multi-mode device 10, the flat panel kV detector 34 and the (e.g., xenon) MV detector 24 are sensitive to both kV and MV energies. Thus, each detector 24, 34 is capable of measuring orthogonal volume scattering during exposure by the other source 20, 30. For example, the MV detector 24 may measure kV scattering with a single but wide row of detectors in the detectors, while the kV detector 34 may measure the object scattering field over an area of, for example, 40 cm by 40 cm. In other embodiments, the MV detector 24 need not be a single row, nor need it be wide.

[0114] In some embodiments, one detector may be used in place of separate detectors 24, 34. For example, kV and MV radiation sources may be positioned adjacent to each other on a circular gantry. Detectors sensitive to both kV and MV radiation may then be located on opposite sides of the gantry. The detector may be actuated to move between at least two positions to receive either kV or MV radiation passing through the isocenter of the system, depending on the position of the detector. Alternatively, a wide detector may be used that is wide enough to simultaneously measure radiation from both the kV and MV beams as a whole. A detector of smaller width may also be used, but may have only a limited field of view from each radiation beam.

[0115] These scatter measurements (possibly with the addition of training data from known objects) can be used to improve scatter correction in the corresponding images. For example, although MV scatter is low enough to be ignored in the MVCT image chain, non-negligible CT inaccuracies and inhomogeneities in MVCT images may be attributed to uncorrected scatter signals. kVCT, especially kV cone-beam CT, may be affected by the larger scatter signal in the measured projections. Measurements of MV detectors of orthogonal kV scatter can be used to better estimate and distinguish the scatter contribution from objects in the bore, thereby improving uniformity and low contrast resolution in kVCT images.

[0116] For example, Fig. 9 900 is a flowchart depicting an exemplary method 900 for combining scan data from multiple radiation modes for scatter correction. Training data 905 from known objects, models, etc. may be provided to improve the process. In some embodiments, a scan configuration (including a scan design for each mode of a multi-mode system) may be determined, and a scan is performed according to method steps 810 and 820 of method 800 to generate scan data 930, 932. The low energy scan data 930 may, for example, be from a low energy kV scan and have a relatively high scatter ratio. The high energy scan data 932 may, for example, be from a high energy wide field MV fan beam scan and have a relatively low scatter ratio. Both projections are in the same transverse plane (s) of the same object scene. At step 940, the method 900 utilizes or combines the low energy scan data 930 and the high energy scan data 932 by estimating the scatter in the low energy kV scan data 930 based on the corresponding high energy MV scan data 932. In other embodiments, the MV detector may also provide a "blank" projection or scan in which the kV scatter signal is measured in the absence of MV x-rays. Then at step 950 , method 900 uses the scatter estimate to reconstruct a low energy kV image.

[0117] In some embodiments, the MV and kV projections are acquired simultaneously or within a short interval (e.g., less than 50 ms). In some embodiments, the MV beam 22 that forms the MV image has a relatively low probability of scattering interactions. In some embodiments, the kV beam 32 that forms the kV image has a relatively high probability of scattering interactions. The relative probabilities can be associated with the scattering mechanisms that fundamentally distinguish low energy radiation from high energy radiation (e.g., photoelectric + Compton vs. Compton only). Compton only can be applicable to high energy radiation sources (e.g., MV). Low energy radiation sources (e.g., kV) may also be subject to photoelectric interactions.

[0118] IB

[0119] In some embodiments, multi-mode devices can be used to reduce metal and beam hardening artifacts. Figure 2 In one embodiment, under kV exposure from a kV source 30, rays from a beam 32 that pass through metal (e.g., such as dental or other surgical implants) or other highly attenuating objects (e.g., such as dense bone or calcifications) may block all or nearly all signals from reaching a detector 34 along rays that pass through the highly attenuating material (preferentially attenuating lower energy photons relative to higher energy photons). This may result in undefined, highly uncertain, or otherwise artificial measurements of attenuation along those rays by the detector 34, resulting in streak artifacts through the object. These artifacts are energy dependent, such that they are less noticeable when imaged by, for example, higher energy photons from the MV source 20. For example, a highly attenuating object may block approximately 70% of a kV signal but only approximately 7% of a MV signal, a difference of approximately ten times. However, higher energy photons (from the MV source 20) produce less intrinsic attenuation contrast in biological tissue than lower energy photons (from the kV source 30). To correct these artifacts while maintaining soft tissue contrast, sparse projection data or reconstructed images from the MVCT system (including MV source 20 and detector 24) can be used to fill in the missing information and reduce artifacts in the kVCT system (including kV source 30 and detector 34).

[0120] For example, Fig.101000 is a flow chart depicting an exemplary method 1000 of combining scan data from multiple radiation modes to reduce metal and beam hardening artifacts. Training data 1005 from known objects, models, etc. can be provided to improve the process. In some embodiments, a scan configuration (including a scan design for each mode of a multi-mode system) can be determined and a scan is performed according to method steps 810 and 820 of method 800 to generate scan data 1030, 1032. The low energy scan data 1030 can be, for example, from a low energy kV scan and have a relatively high attenuation, such as dominated by photoelectric absorption. The high energy scan data 1032 can be, for example, from a high energy wide field MV fan beam scan and have a relatively low known attenuation dominated by a different physical mechanism (Compton scattering). Both projections are in the same transverse plane(s) of the same object scene. At step 1040, method 1000 utilizes or combines low energy scan data 1030 and high energy scan data 1032 by estimating attenuation of kV projections through dense structures dominated by photoelectric absorption in low energy kV scan data 1030 based on corresponding high energy MV scan data 1032. Then at step 1050, method 1000 reconstructs a low energy kV image using the attenuation estimate.

[0121] In some embodiments, the MV and kV projections are acquired simultaneously or within a short interval (e.g., less than 50 ms). In some embodiments, the MV beam 22 forming the MV image has a peak energy of about 3 MeV and an average energy of about 1 MeV. In some embodiments, the kV beam 32 forming the kV image has a peak energy less than or equal to 150 keV.

[0122] IC

[0123] In some embodiments, the multi-mode device can be used for temporal resolution correction (eg, image blur correction). Figure 2In the multi-modal device 10, in one embodiment, the MV projections from the MV source 20 are sharply resolved in time (e.g., about 5 μs) compared to the kV projections from the kV source 30 (e.g., about 10 ms), and are therefore sharply resolved at the gantry angle. In addition, the achievable pulse rate of the MV beam 22 is higher (e.g., up to 300 Hz) compared to the typical pulse rate of the kV beam 32 of the kV-CBCT system (e.g., about 15 Hz). Whether it is continuous or pulsed exposure, the blur in the kV projection increases with the exposure time and the gantry rate. In one embodiment, based on the geometry and kV operation, the degree of blur on the detector 34 can be, for example, about 10 pixels, and 2D correction or 3D modeling may be required. For example, in a model-based 3D scheme, the MV projections can provide time-resolved information to improve the consistency of the model-based reconstruction, or to regularize the 2D deblurring operator.

[0124] For example, Fig.11 1 is a flow chart depicting an exemplary method 1100 for combining scan data from multiple radiation modes for temporal resolution correction (e.g., image blur correction for lung or heart imaging). Training data 1105 from known objects, models, etc. may be provided to improve the process. In some embodiments, a scan configuration (including a scan design for each mode of a multi-mode system) may be determined, and a scan is performed according to method steps 810 and 820 of method 800 to generate scan data 1130, 1132. Low energy scan data 1130 may, for example, be from a low energy kV scan and have a relatively low pulse rate (e.g., slow integration). For example, a typical kV integration time may be 5-20 ms. However, since the pulse rate is 1 / cycle period (the cycle period includes the readout time of the detector), it may have a range of 10-100 ms. High energy scan data 1132 may, for example, be from a high energy MV scan and have a relatively high pulse rate (e.g., fast integration). For example, a typical MV integration time may be 1-10 us. The cycle time of the MV system is not limited by the integration time. In one embodiment, rates up to 300 Hz are used with a cycle time of 3.3 ms. At step 1140, the method 1100 utilizes or combines the low energy scan data 1130 and the high energy scan data 1132 by using the MV scan data 1132 with higher temporal discrimination to assist in the interpolation of the kV scan data 1130 with better spatial images with fewer time point estimates for image blur correction. The method 1100 then reconstructs the low energy kV image using image blur correction at step 1150, e.g., for a sharp temporal resolution motion deblurred image.

[0125] In some embodiments, the high energy scan is MV fan beam CT and the low energy scan is kV narrow beam CT. In some embodiments, the high energy scan is MV fan beam CT and the low energy scan is kV cone beam CT.

[0126] ID

[0127] In some embodiments, the multi-mode device can be used for motion artifact correction. Figure 2 In one embodiment of the multi-mode device 10, as described above, the MV projections from the MV source 20 are more sharply temporally resolved than the kV projections from the kV source 30.

[0128] For example, Fig.1212 is a flow chart depicting an exemplary method 1200 for combining scan data from multiple radiation modes for motion artifact correction. Training data 1205 from known subjects, models, etc. may be provided to improve the process. In some embodiments, a scan configuration (including a scan design for each mode of a multi-mode system) may be determined, and a scan is performed according to method steps 810 and 820 of method 800 to generate scan data 1230, 1232. The low energy scan data 1230 may, for example, be from a low energy kV scan and have less sharp temporal resolution (e.g., low frequency). The high energy scan data 1232 may, for example, be from a high energy MV scan and have sharper temporal resolution (e.g., high frequency). At step 1240, the method 1200 utilizes or combines the low energy scan data 1230 and the high energy scan data 1232 by using the MV scan data 1232 with sharper temporal resolution projections to estimate motion in motion correction for the kV scan data 1230 with motion artifacts. For example, in one embodiment of step 1240, the method 1200 combines the low-frequency kV scan data 1230 and the high-frequency MV scan data 1232 to establish a correlation model between the high-frequency MV scan data 1232 and the combined image data, and then uses the high-frequency MV scan data 1232 to interpolate the high-frequency motion included in the low-frequency kV projection data 1230 based on the correlation model 1240. Then at step 1250, the method 1200 uses motion correction to reconstruct the low-energy kV image. In another embodiment, step 1250 can otherwise include reconstructing the high-frequency motion trajectory. In other embodiments, in addition to having different projection frequencies for the low-energy scan data 1230 and the high-energy scan data 1232, the projection integration time can be different. For example, the low-energy scan data 1230 (e.g., kV projection) can have a longer integration time (e.g., 5-30ms), while the high-energy scan data 1232 (e.g., MV projection) can have a shorter integration time (e.g., ~0.001ms). In these embodiments, the high energy scan data 1232 may be used to remove rotational or motion blur inherent in the low energy scan data 1230 .

[0129] In various embodiments, the high energy scan is an MV scan (e.g., MV fan beam CT) and the low energy scan is a kV scan (e.g., kV narrow beam CT or kV cone beam CT). In various embodiments, the viewing angles between the high energy source 20 and the low energy source 30 are orthogonal. In one embodiment, motion correction is based on motion estimation (which is based on 3D reconstruction) and is applied to the second radiation source as a real-time adjustment (e.g., orientation, collimation, and / or gating for uncontrolled motion, etc.) when the second radiation source is used simultaneously to deliver therapeutic radiation.

[0130] II.A.

[0131] In some embodiments, multi-modal devices can be used for material separation and / or quantitative imaging. Figure 2 In the multi-mode device 10, in various embodiments, MV projections from the MV source 20 and kV projections from the kV source 30 can be acquired in a simultaneous, interleaved, or serial manner. Images derived from different energy spectra (e.g., high energy source 20 and low energy source 30) provide linearly independent measurements of material properties. In general, more accurate mass / electron density estimates can be obtained from MV images than from kV images, but kV-kV registration may be more accurate than kV / MV registration. In various embodiments, these differences can be used to decompose projection maps and voxels into linear combinations of two basis materials (e.g., "soft tissue" and "bone"). By changing the contribution of the basis material, one material can be suppressed while enhancing another material, thereby improving image quality.

[0132] For example, Fig.13 13 is a flow chart depicting an exemplary method 1300 for combining scan data from multiple radiation modes for material separation and / or quantitative imaging. Training data 1305 from known objects, models, etc. may be provided to improve the process. In some embodiments, a scan configuration (including a scan design for each mode of a multi-mode system) may be determined, and a scan is performed according to method steps 810 and 820 of method 800 to generate scan data 1330, 1332. The low energy scan data 1330 may be from a low energy kV scan, for example. The high energy scan data 1332 may be from a high energy MV scan, for example, wherein the MV scan data 1332 and the low energy scan data 1330 provide linearly independent measurements of at least one material property of the object. At step 1340, the method 1300 changes the contribution of at least one basis material according to at least one of the scan data 1330, 1332. Then at step 1350, the method 1300 reconstructs an image using the changed contribution of the at least one basis material.

[0133] In one embodiment, varying the contribution of at least one base material from at least one of the scan data 1330, 1332 provides a quantitative image of the electron density. In some embodiments, the low energy scan data 1330 includes projection data associated with at least two spectrally separated keV energies.

[0134] II.B.

[0135] In some embodiments, a multi-modal device may be used in a patient setting. Figure 2The multi-modality device 10, in one embodiment, can use 2D dual energy images (e.g., from a high energy source 20 and a low energy source 30) in a 2D image registration workflow, for example, to switch between bone or soft tissue. In one embodiment, the registration scan can be a low dose, two angle, two energy scout scan, where the return scan is at a 90 degree gantry shift so that MV projections and kV projection pairs are available from two angles in each plane. Due to the exemplary fixed 90 degree offset of the MV and kV sources, only one of these angles has a matching ray angle. The second angle will only obtain non-complementary sector data from the opposite side of the gantry 12.

[0136] For example, Fig.14 1 is a flow chart depicting an exemplary method 1400 for combining scan data from multiple radiation modes for patient setup. The prior data 1405 may be from a known prior image, object, model, etc. In some embodiments, a scan configuration (including a scan design for each mode of a multi-mode system) may be determined, and a scan is performed according to method steps 810 and 820 of method 800 to generate scan data 1430, 1432. The low energy scan data 1430 may be from a low energy kV scan, for example. The high energy scan data 1432 may be from a high energy MV scan, for example. In this embodiment, the high energy scan and the low energy scan are performed simultaneously, and the high energy source 20 and the low energy source 30 are orthogonal as part of a scout scan workflow. At step 1440, the method 1400 utilizes or combines the low energy scan data 1430 and the high energy scan data 1432 to generate (one or more) registration images. Then at step 1450, the method 1400 registers the patient based on the low energy and high energy images.

[0137] In some embodiments, the scout scan is bidirectional to acquire dual energy projections from the same gantry angle. In some embodiments, geometrically coincident dual energy projections are used for material separation in a registration workflow.

[0138] II.C

[0139] In some embodiments, the multi-mode device can be used for online adaptive IGRT, as well as offline adaptive IGRT and irradiation quality assurance. Figure 2The multi-modality device 10, in one embodiment, uses a kV subsystem (including, for example, a low energy source 30, a beam former 36, and a detector 34) for online 3D motion adaptation. The embodiment also includes using the projection data of the MV radiotherapy beam 22 to both improve the image quality at the planning target volume (PTV) and use it as a constraint on the quantitative image of the electron density. Here, the data of the MV exit detector 24 is utilized in the dual energy iterative reconstruction by forward projecting the MLC apertures in the MVCT geometry and enforcing the consistency of the projection data. For example, there may be 51 MLC apertures per rotation, and the high energy MV source 20 may be pulsed at 300 Hz, resulting in a large number of detector counts, where the image information is concentrated on the treatment structure. The data can be used to achieve low noise quantitative images of the treatment area. The low noise view enables deformable PTV tracking in addition to rigid motion tracking, so that the plan can be adapted to the shape and position of the PTV online.

[0140] For example, Fig.15 1 is a flow chart depicting an exemplary method 1500 for combining scan data from multiple radiation modes for online adaptive IGRT. Prior data 1505 may be from known prior images, treatment plans, subjects, models, etc. In some embodiments, a scan configuration (including a scan design for each mode of a multi-mode system) may be determined, and a scan may be performed according to method steps 810 and 820 of method 800 to generate scan data 1530, 1532. The low energy scan data 1530 may be from a low energy kV scan, for example. The high energy scan data 1532 may be from a high energy MV scan, for example. At step 1540, the method 1500 utilizes or combines the low energy scan data 1530 and the high energy scan data 1532 to supplement and / or constrain the other scan data 1530, 1532. Then at step 1550, the method 1500 adjusts the treatment plan based on the supplemented and / or constrained other scan data.

[0141] In some embodiments, fluence field modulation imaging includes supplementing lost MV view information by orthogonal kV projections. In some embodiments involving online 3D kV imaging, MV treatment projections are used as constraints on quantitative images of electron density. In one embodiment, the online quantitative images are used for online dose calculations. In another embodiment, the calculated dose is used in an offline adaptive workflow. In another embodiment, the calculated dose is used in a quality assurance workflow.

[0142] In some embodiments, the above methods may be performed simultaneously or in an interleaved manner based on a preferred workflow. For example, multi-mode scanning may be performed and the resulting scan data may be used for two or more of the various features and benefits described above.

[0143] When the above apparatus and methods are used in the projection domain, they may be applied to each projection view, where each projection view is a planar image. Various embodiments may utilize different scanning geometries, detector positioning (including offset detectors), and / or beamformer window shapes.

[0144] As described above, aspects of the disclosed technology can be used in radiation therapy apparatus and methods utilizing a multi-mode radiation source, including an integrated low energy (e.g., kV) source and a high energy (e.g., MV) source for use in conjunction with or as part of IGRT. According to one embodiment, an image acquisition method can include or otherwise utilize a helical source trajectory (e.g., continuous source rotation about a central axis and longitudinal movement of a patient support through a gantry aperture) or circular scanning, and rapid slip ring rotation, for example to provide kV CT imaging on a radiation therapy delivery platform.

[0145] In some embodiments, it will be appreciated that any potential increased scan time associated with multiple beam rotations to complete a volumetric image can be mitigated or otherwise offset by high kV frame rates, high gantry rates, and / or sparse data reconstruction techniques. It will also be appreciated that the selectively controllable collimator / beam shaper provided above allows for a system in which a user can trade off or otherwise alter the relationship between image acquisition time and image quality based on a particular application and / or clinical need. It should also be appreciated that the radiation therapy delivery device can be controlled to provide semi-rotational or single-rotation cone beam CT scans (which may reduce image quality due to scatter) with fast image acquisition times (e.g., for motion tracking), as well as circular or continuous spiral acquisitions with narrow / slit fan beams, which have longer acquisition times but improve image quality due to reduced scatter. One or more optimization processes may also be applied to all of the above embodiments to determine scan design, determine beam positioning, determine read range, estimate scatter, etc.

[0146] Fig.161 is a flowchart depicting an exemplary method 1600 for IGRT using a radiotherapy device (including, for example, the multi-mode device 10). Prior data 1605 may include images of the patient (e.g., prior images, which may be previously acquired planning images, including prior CT images, as described above), treatment plans, phantom information, models, prior information, etc. In some embodiments, the prior data 1605 is generated by the same radiotherapy device but at an earlier time. At step 1610, imaging of the patient is performed using a radiation source (e.g., kV radiation from source 30 of the multi-mode device 10 and / or MV radiation from source 20 of the multi-mode device 10). In various embodiments, the imaging includes a spiral or circular scan with a fan beam or cone beam geometry. Step 1610 may produce (one or more) high quality (HQ) images or imaging / scan data 1615 using the above-described techniques. In some embodiments, the image quality may be adjusted to optimize the balance between image quality / resolution and dose. In other words, not all images need to be of the highest quality, or the image quality may be adjusted to optimize or weigh the balance between image quality / resolution and image acquisition time. The imaging step 1610 also includes image processing 1620 to generate a patient image based on the imaging / scanning data 1615 (e.g., according to the methods described above). Although the image processing step 1620 is shown as part of the imaging step 1610, in some embodiments, the image processing step 1620 is a separate step, including image processing performed by a separate device.

[0147] Next, at step 1630, one or more image-based pre-irradiation steps discussed below are performed based at least in part on the imaging / scanning data 1615 from step 1610. As discussed in more detail below, step 1630 may include determining various parameters associated with the therapeutic treatment and (subsequent) imaging plan. In some embodiments, the image-based pre-irradiation steps (1630) may require more imaging (1610) before the radiation therapy irradiation (1640). Step 1630 may include adapting the treatment plan based on the imaging data 1615 as part of an adaptive radiation therapy routine. In some embodiments, the image-based pre-irradiation steps 1630 may include real-time treatment planning. As described above, embodiments may also include simultaneous, overlapping, and / or alternating activation of imaging and therapeutic radiation sources. Real-time treatment planning may involve any or all of these types of imaging and therapeutic radiation activation techniques (simultaneous, overlapping, and / or alternating).

[0148] Next, at step 1640, therapeutic radiation therapy delivery is performed using a high energy radiation source (e.g., MV radiation from radiation source 20). Step 1640 delivers a radiation therapy dose 1645 to the patient in accordance with the treatment plan. In some embodiments, the IGRT method 1600 may include returning to step 1610 to perform additional imaging at various intervals (e.g., intervals between fractions), followed by image-based pre-delivery steps (1630) and / or radiation therapy delivery (1640) as needed. In this manner, high quality imaging data 1615 may be generated and utilized during IGRT using a device 10 capable of adaptive therapy. As described above, steps 1610, 1630, and / or 1640 may be performed simultaneously, overlapping, and / or alternatingly.

[0149] As described above, IGRT can include at least two overall goals: (i) delivering a highly conformal dose distribution to a target volume; and (ii) delivering the radiation beam with a high degree of accuracy throughout 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 beam requires the ability to identify and / or track the location of the target volume within the treatment fraction through high quality images. The ability to increase the rate of delivery requires the ability to accurately, precisely, and quickly move the radiation source according to the treatment plan.

[0150] Fig.17 1700 is a block diagram depicting exemplary image-based pre-irradiation steps / options that may be associated with step 1630 above. It will be appreciated that, without departing from the scope of the present invention, the multi-modal device 10 described above (e.g., as part of a radiotherapy apparatus) may generate low-energy and high-energy images that may be used in a variety of ways, including images for image-based pre-irradiation steps (1630). For example, the image 1615 generated by the radiotherapy apparatus may be used to set up or align the patient (1710) prior to treatment. Patient alignment may include correlating or registering current imaging data 1615 with imaging data associated with earlier pre-treatment scans and / or plans (including treatment plans). Patient alignment may also include feedback on the patient's physical position relative to the radiation source to verify that the patient is physically within range of the irradiation system. If necessary, the patient may be adjusted accordingly. In some embodiments, patient alignment imaging may be purposefully of lower quality to minimize dose but provide sufficient alignment information. An exemplary patient alignment process is described below.

[0151] The images generated by the multimodal device 10 may also be used for treatment planning or re-planning (1720). In various embodiments, step 1720 may include confirming the treatment plan, modifying the treatment plan, generating a new treatment plan, and / or selecting a treatment plan from a collection of treatment plans (sometimes referred to as a "daily plan"). For example, if the imaging data 1615 indicates that the target volume or ROI is the same as when the treatment plan was developed, the treatment plan can be confirmed. However, if the target volume or ROI is different, the therapeutic treatment may need to be re-planned. In the case of re-planning, due to the high quality of the imaging data 1615 (generated by the multimodal device 10 at step 2010), the imaging data 2015 can be used for treatment planning or re-planning (e.g., generating a new or revised treatment plan). In this way, pre-treatment CT imaging via a different device is not required. In some embodiments, confirmation and / or re-planning can be an ongoing procedure before and / or after various treatments.

[0152] According to another exemplary use case, the images generated by the multi-modality device 10 can be used to calculate an imaging dose (1730), which can be used in an ongoing determination of a total dose to a patient and / or for subsequent imaging planning. The quality of subsequent imaging can also be determined as part of treatment planning, for example to balance quality and dose. According to another exemplary use case, the images generated by the multi-modality device 10 can be used to calculate a radiation therapy dose (1740), which can be used in an ongoing determination of a total dose to a patient and / or can be included as part of treatment planning or re-planning.

[0153] According to other exemplary use cases, images generated by the multimodal device 10 may be used in conjunction with planning or adjusting other imaging (1750) and / or other treatment (1760) parameters or plans, including, for example, as part of adaptive therapy and / or treatment plan generation. According to another exemplary use case, images generated by the multimodal device 10 may be used in conjunction with adaptive therapy monitoring (1770), which may include monitoring radiation therapy delivery and adaptively adjusting, including replanning, as needed.

[0154] It should be understood that the image-based pre-irradiation steps (1630) are not mutually exclusive. For example, in various embodiments, calculating the radiation therapy dose (1740) can itself be a step and / or can be part of adaptive treatment monitoring (1770) and / or treatment planning (1720). In various embodiments, the image-based pre-irradiation steps (1630) can be performed automatically and / or manually with human involvement.

[0155] Fig.181600 is a block diagram depicting exemplary data sources that may be used during imaging (1610) and / or subsequent image-based pre-irradiation steps (1630). Detector data 1810 represents data received by the radiation detectors 24, 34. Projection data 1820 is data generated by radiation incident in the collimated beam region (referred to above as the effective region). Penumbra data 1830 is data generated by radiation incident in the penumbra region. Scatter data 1840 is data generated by radiation incident in the peripheral region outside the penumbra region as described above and / or scatter determined as described above. In another embodiment, the scatter data 1740 may be used to determine the residual effect of scatter from the therapeutic radiation source 20 (e.g., MV) when both sources 20, 30 are operated simultaneously or in an interleaved manner.

[0156] In this manner, the penumbra data 1830 and / or scatter data 1840 may be used to improve the quality of the images generated by the imaging step 1610. In some embodiments, the penumbra data 1830 and / or scatter data 1840 may be combined with the projection data 1820 and / or may be analyzed according to applicable imaging settings 1850, treatment settings 1860 (e.g., if simultaneous imaging and therapeutic radiation), and any other data 1870 associated with the multi-modality device 10 when data is collected at the detectors 24, 34. In other embodiments, the data may be used in the treatment planning step 1630.

[0157] Fig.19 and Fig. 20 Exemplary embodiments of imaging 1610, image-based pre-irradiation steps 1630, and radiation therapy administration 1640 use cases are depicted, including examples of various forward and feedback sequences associated with on-board imaging using the multi-modality device 10 during IGRT, including using the above-described methods.

[0158] Fig.191 is a flow chart depicting an exemplary method 1900 including patient setup or alignment using a radiotherapy apparatus (including, for example, a multi-mode device 10). Prior data 1905 may include images of the patient (e.g., prior images, which may be previously acquired planning images, including prior CT images as described above). In some embodiments, the prior data 1905 is generated by the same radiotherapy apparatus but at an earlier time. At step 1910, an initial or preliminary alignment of the patient may be performed. Then, at step 1920, an onboard imaging scan is performed using a low-energy and / or high-energy radiation source (e.g., kV radiation from source 30 and / or MV radiation from source 20) of the multi-mode device 10, including, for example, as described in step 1610 above. In various embodiments, the onboard imaging includes a spiral or circular scan using a fan beam or cone beam geometry. Step 1920 generates online imaging / scan data 1930 using the above-described techniques. The imaging step 1920 may also include image processing to generate patient images based on the imaging / scanning data 1930 (eg, according to the methods described above), including, for example, as described in block 1620 above.

[0159] Next, step 1940 determines whether alignment correction is required based at least in part on the online scan data 1930, including, for example, as described in block 1710 above. If alignment correction or adjustment is required, the method 1900 proceeds to step 1950 to perform alignment correction based at least in part on the online scan data 1930. Then, after alignment correction, the method may return to step 1920 to perform additional imaging as a confirmation or further refinement cycle. If alignment correction or adjustment is not required from step 1940, the method 1900 proceeds to step 1960 to perform radiation therapy delivery. Then, after treatment, the method 1900 may return to step 1920 to perform additional imaging as a confirmation or further refinement cycle.

[0160] Fig. 202000 is a flow chart depicting an exemplary method 2000 for using a radiotherapy apparatus (including, for example, the multi-mode device 10) including adaptive IGRT. A prior treatment plan 2005 may include a treatment plan as well as images of the patient (e.g., prior images, which may be previously acquired planning images, including prior CT images, as discussed above), phantom information, models, prior information, etc. In some embodiments, the prior data 2005 is generated by the same radiotherapy apparatus but at an earlier time. At step 2010, an initial or preliminary treatment plan may be adopted, for example, based on the prior treatment plan and any additional information. Then, at step 2020, an on-board imaging scan is performed using a low-energy and / or high-energy radiation source (e.g., kV radiation from source 30 and / or MV radiation from source 20) of the multi-mode device 10, including, for example, as described in step 1610 above. In various embodiments, the on-board imaging includes a spiral or circular scan with a fan beam or cone beam geometry. Step 2020 generates online imaging / scan data 2030 using the above-described techniques. The imaging step 2020 may also include image processing to generate patient images based on the imaging / scanning data 2030 (eg, according to the methods described above), including, for example, as described in block 1620 above.

[0161] Next, step 2040 determines whether the treatment plan needs to be replanned or adjusted based at least in part on the online scan data 2030, including, for example, as described above in block 1720. If the treatment plan does not need to be adjusted or replanned, the method 2000 proceeds to step 2050 for radiation therapy delivery. If the treatment plan does need to be adjusted or replanned, the method 2000 proceeds to step 2060 for adjusting the treatment plan based at least in part on the online scan data 2030. Then, after adjusting the treatment plan, the method can proceed to step 2050 for radiation therapy delivery. Then, after treatment, the method 2000 can return to step 2020 for additional imaging as a confirmation or further refinement cycle.

[0162] In some embodiments, methods 1900, 2000, and other methods may be performed simultaneously or in an interleaved manner based on a preferred workflow. For example, an onboard imaging scan may be performed and used as both 1920 and 2020 scans to simultaneously confirm treatment and continued alignment using the same data. In other embodiments, two or more image-based pre-irradiation steps 1630 may be performed simultaneously or in an interleaved manner based on a preferred workflow, including situations where the same imaging data 1615 and / or image processing 1620 is used for more than one of the image-based pre-irradiation steps 1630.

[0163] Although the disclosed technology has been shown and described for a certain aspect, one or more embodiments, it is obvious that after reading and understanding this specification and the accompanying drawings, other technicians in the field will think of equivalent variations and modifications. In particular, with respect to the various functions performed by the above-mentioned elements (components, assemblies, devices, components, compositions, etc.), unless otherwise specified, the terms used to describe such elements (including references to "devices") are intended to correspond to any element that performs the specified function of the element (i.e., functionally equivalent), even if the structure is not structurally equivalent to the disclosed structure that performs the function of the exemplary aspects or embodiments of the disclosed technology shown herein. In addition, although the specific features of the disclosed technology may have been described above for only one or more of several illustrated aspects or embodiments, the feature can be combined with one or more other features of other embodiments as needed, and this is advantageous for any given or specific application.

[0164] Although the embodiments discussed herein have been related 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 discussed herein. Although the present invention has been illustrated by the description of its embodiments, and although the embodiments have been described in detail, it is not the applicant's intention to limit or in any way limit the scope of the appended claims to these details. Other advantages and modifications will be apparent to those skilled in the art. Therefore, the present invention in its broader aspects is not limited to the specific details, representative devices and methods, and illustrative examples shown and described. Therefore, these details may be deviated from without departing from the spirit or scope of the applicant's overall inventive concept.

Claims

1. A multi-mode imaging device, comprising: a rotatable gantry system positioned to at least partially surround a patient support; a first radiation source coupled to the rotatable gantry system, the first radiation source configured for imaging radiation; a second radiation source coupled to the rotatable gantry system, the second radiation source configured for both imaging radiation and therapeutic radiation, wherein the second radiation source has an energy level exceeding that of the first radiation source; and a first radiation detector coupled to the rotatable gantry system and positioned to receive radiation from at least one of the first radiation source or the second radiation source; wherein first measured projection data from the first radiation source has greater attenuation than second measured projection data from the second radiation source, and wherein a first attenuation estimate associated with the first measured projection data is based on the second measured projection data; and The radiation attenuation estimate associated with the first measured projection data is generated by estimating the attenuation of the first measured projection data through a dense structure dominated by photoelectric absorption based on the second measured projection data.

2. The device according to claim 1, wherein: The first radiation source comprises a kilo-electron-volt peak photon energy keV up to 150 keV, and the second radiation source comprises a mega-electron-volt peak photon energy MeV of 1 MeV or greater.

3. The device according to claim 1, wherein: The second radiation source includes a peak energy of 3 MeV and an average energy of 1 MeV.

4. The device according to claim 1, wherein: The first measured projection data and the second measured projection data are acquired simultaneously or within 50 ms of each other.

5. The device according to claim 1, wherein: The second measured projection data includes sparse projection data.

6. The device according to claim 1, wherein: The first measured projection data or the second measured projection data is measured during a helical scan.

7. The device according to claim 1, wherein: The first measured projection data or the second measured projection data are measured during a circular scan.

8. The apparatus of claim 1, further comprising at least one beam shaper configured to adjust a shape of a radiation beam emitted by the first radiation source or the second radiation source.

9. The device according to claim 1, wherein: At least one of the first radiation source or the second radiation source is configured to produce a fan beam shape.

10. The device according to claim 1, wherein: At least one of the first radiation source or the second radiation source is configured to produce a cone beam shape.

11. The apparatus of claim 1, further comprising a reconstruction processor configured to generate a reconstructed image based on the first attenuation estimate and the first measured projection data.

12. The device according to claim 1, wherein: The first measured projection data has greater scatter than the second measured projection data, and wherein a first scatter estimate associated with the first measured projection data is based on the second measured projection data.

13. The apparatus according to claim 1, wherein: The first measured projection data is measured at a first frequency, the second measured projection data is measured at a second frequency, the first frequency is less than the second frequency, and wherein the interpolation of the first measured projection data is based on the second measured projection data.

14. The apparatus according to claim 1, wherein: The first measured projection data is measured at a first frequency, the second measured projection data is measured at a second frequency, the first frequency is less than the second frequency, and wherein the motion estimation of the first measured projection data is based on the second measured projection data.

15. The apparatus according to claim 1, wherein: The first radiation source is coupled to a first rotatable gantry of the rotating gantry system, and wherein the second radiation source is coupled to a second rotatable gantry of the rotating gantry system.

16. The apparatus of claim 1, further comprising a second radiation detector, wherein: The first radiation detector is positioned to receive radiation from the first radiation source, and the second radiation detector is positioned to receive radiation from the second radiation source.

17. The apparatus according to claim 1, wherein: The first measured projection data is integrated over a first time, the second measured projection data is integrated over a second time, the first time is longer than the second time, and wherein reconstruction of the first measured projection data is based on the second measured projection data.

18. The apparatus according to claim 1, wherein: The first measured projection data and the second measured projection data are acquired sequentially.

19. A method for correcting image artifacts using a multi-mode imaging device, comprising: receiving first measured projection data from a first radiation source configured for imaging radiation; receiving second measured projection data from a second radiation source configured for both imaging radiation and therapeutic radiation, wherein the second radiation source has an energy level exceeding that of the first radiation source, and wherein the first measured projection data has a greater attenuation than the second measured projection data; and determining a first attenuation estimate associated with the first measured projection data based on the second measured projection data; Wherein the radiation attenuation estimate associated with the first measured projection data is generated by estimating the attenuation of the first measured projection data through a dense structure dominated by photoelectric absorption based on the second measured projection data.

20. The method according to claim 19, wherein: The first measured projection data and the second measured projection data are acquired simultaneously or within 50 ms of each other.

21. The method of claim 19, further comprising: An image is reconstructed based on the first attenuation estimate and the first measured projection data.

22. The method according to claim 21, further comprising: The patient is registered based on the reconstructed images during the patient registration workflow.

23. The method according to claim 21, further comprising: The treatment plan is modified based on the reconstructed images during the adaptive planning workflow.

24. The method of claim 21, further comprising: The therapeutic dose delivered to the patient is calculated based on the reconstructed images.

25. A radiotherapy irradiation device, comprising: a rotatable gantry system positioned to at least partially surround a patient support; a first radiation source coupled to the rotatable gantry system, the first radiation source configured for imaging radiation; a second radiation source coupled to the rotatable gantry system, the second radiation source configured for both imaging radiation and therapeutic radiation, wherein the second radiation source has an energy level exceeding that of the first radiation source; and a first radiation detector coupled to the rotatable gantry system and positioned to receive radiation from at least one of the first radiation source or the second radiation source; wherein first measured projection data from the first radiation source has greater attenuation than second measured projection data from the second radiation source, and wherein a first attenuation estimate associated with the first measured projection data is based on the second measured projection data; and A data processing system configured to: receiving measured projection data from the first radiation source and the second radiation source, wherein first measured projection data from the first radiation source has a greater attenuation than second measured projection data from the second radiation source; determining a first attenuation estimate associated with the first measured projection data based on the second measured projection data; and combining the first measured projection data and the first attenuation estimate to reconstruct an image during IGRT; Wherein the radiation attenuation estimate associated with the first measured projection data is generated by estimating the attenuation of the first measured projection data through a dense structure dominated by photoelectric absorption based on the second measured projection data.

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