Multimodal Radiation Devices and Methods

Abstract

Multimodal imaging devices and methods include rotatable gantry systems with multiple radiation sources, including those with different energy levels (e.g., kV and MV). Through high-speed slip-ring techniques and helical scanning, data from multiple radiation sources can be combined or utilized to generate improved images and workflows, including those for IGRT. Features include increased spatial registration accuracy between image sets to enable more precise radiation therapy delivery, reduced image artifacts (e.g., scatter, metal and beam hardening, image blur, motion, etc.), and the use of dual-energy imaging (e.g., material separation and quantitative imaging, patient setup, online adaptive IGRT, etc.).

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. Provisional Patent Application No. 62 / 773,712, filed November 30, 2018 (Attorney Docket No. 38935 / 04001); U.S. Provisional Patent Application No. 62 / 773,700, filed November 30, 2018 (Attorney Docket No. 38935 / 04002); U.S. Provisional Patent Application No. 62 / 796,831, filed January 25, 2019 (Attorney Docket No. No. 38935 / 04004; U.S. Provisional Patent Application No. 62 / 800,287 (Attorney Docket No. 38935 / 04003), filed February 1, 2019; U.S. Provisional Patent Application No. 62 / 801,260 (Attorney Docket No. 38935 / 04006), filed February 5, 2019; U.S. Provisional Patent Application No. 62 / 813,335 (Attorney Docket No. 38935 / 04006), filed March 4, 2019 No. 38935 / 04007; U.S. Provisional Patent Application No. 62 / 821,116, filed March 20, 2019 (Attorney Docket No. 38935 / 04009); U.S. Provisional Patent Application No. 62 / 836,357, filed April 19, 2019 (Attorney Docket No. 38935 / 04016); U.S. Provisional Patent Application No. 62 / 836,352, filed April 19, 2019 No. 62 / 878,364, filed on July 25, 2019 (Attorney Docket No. 38935 / 04008); and U.S. Provisional Application No. 62 / 843,796, filed on May 6, 2019 (Attorney Docket No. 38935 / 04017). This application is also filed in attorney docket no. 38935 / 04020, entitled "APPARATUS AND METHODS FOR SCALABLE FIELD OF VIEW IMAGING USING A MULTI-SOURCE SYSTEM"; attorney docket no. 38935 / 04011, entitled "INTEGRATED HELICAL FAN-BEAM COMPUTED TOMOGRAPHY IN IMAGE-GUIDED RADIATION TREATMENT DEVICE"; attorney docket no. 38935 / 04010, entitled "COMPUTED TOMOGRAPHY SYSTEM AND METHOD FOR IMAGE IMPROVEMENT USING PRIOR IMAGE";Attorney Docket No. 38935 / 04013 entitled "OPTIMIZED SCANNING METHODS AND TOMOGRAPHY SYSTEM USING REGION OF INTEREST DATA";Attorney Docket No. 38935 / 04015 entitled "HELICAL CONE-BEAM COMPUTED TOMOGRAPHY IMAGING WITH AN OFF-CENTERED DETECTOR";Attorney Docket No. 38935 / 04021 entitled "MULTI-PASS COMPUTED TOMOGRAPHY SCANS FOR IMPROVED WORKFLOW AND PERFORMANCE";Attorney Docket No. 38935 / 04012 entitled "METHOD AND APPARATUS FOR SCATTER ESTIMATION IN CONE-BEAM COMPUTED TOMOGRAPHY";Attorney Docket No. 38935 / 04013 entitled "ASYMMETRIC SCATTER FITTING FOR OPTIMAL PANEL READOUT IN CONE-BEAM COMPUTED This application relates to ten non-provisional U.S. patent applications filed on the same day, including Attorney Docket No. 38935 / 04014, entitled "METHOD AND APPARATUS FOR IMPROVING SCATTER ESTIMATION AND CORRECTION IN IMAGING," Attorney Docket No. 38935 / 04018, entitled "METHOD AND APPARATUS FOR IMAGE RECONSTRUCTION AND CORRECTION USING INTER-FRACTIONAL INFORMATION," and Attorney Docket No. 38935 / 04022, entitled "METHOD AND APPARATUS FOR IMAGE RECONSTRUCTION AND CORRECTION USING INTER-FRACTIONAL INFORMATION." The contents of all of the above-identified patent application(s) and patent(s) are hereby incorporated by reference in their entirety.

[0002] Aspects of the disclosed techniques relate to utilizing multimodal radiation for imaging, and more particularly, to utilizing a combination of low energy radiation (e.g., kilovoltage (kV)) and high energy radiation (e.g., megavoltage (MV)) to enhance imaging, including computed tomography (CT) scans. [Background technology]

[0003] Pathological anatomical structures such as tumors and lesions can be treated with invasive procedures such as surgery, which can be harmful and risky for the patient. A non-invasive method for treating pathological anatomical structures (e.g., tumors, lesions, vascular malformations, neurological disorders, etc.) is external beam radiation therapy. It typically uses a therapeutic radiation source, such as a linear accelerator (LINAC), to generate radiation beams, such as X-rays. In one type of external beam radiation therapy, the therapeutic radiation source directs a series of X-ray beams at the tumor site from multiple angles, with the patient positioned within the imaging field of the beam. As the angle of the therapeutic radiation source changes, all the beams pass through the tumor site, but pass through different areas of healthy tissue on the way to and from the tumor. As a result, the cumulative radiation dose at the tumor is high and the cumulative radiation dose to the healthy tissue is relatively low.

[0004] The term "surgical irradiation" refers to a procedure in which radiation is applied to a target area at a dose sufficient to necrotize a lesion in fewer treatment sessions or fractions than would be achieved by delivering a low dose per fraction at a mass rate. Surgical irradiation is typically characterized by a relatively high radiation dose per fraction (e.g., 500-2000 centigrays) and hypofractionated radiation (e.g., 1-5 fractions or treatment days) to distinguish it from radiation therapy, which is typically characterized by a low dose per fraction (e.g., 100-200 centigrays) and hyperfractionated radiation (e.g., 30 to 45 fractions). For convenience, the terms "radiation treatment" and "radiation therapy" are used interchangeably herein to mean surgical irradiation and / or radiation therapy, unless otherwise specified.

[0005] Image-guided radiation therapy (IGRT) systems include gantry-based systems and robotic arm-based systems. In a gantry-based system, the gantry rotates the therapeutic radiation source around an axis passing through the isocenter. The gantry-based system includes a C-arm gantry, in which the therapeutic radiation source is mounted on it in a cantilever-like manner and rotates around an axis passing through the isocenter. The gantry-based system further includes a ring gantry, which generally has an annular shape in which the patient's body extends through the bore of the ring / toroid, and the therapeutic radiation source is mounted on the ring circumference and rotates around an axis passing through the isocenter. Conventional gantry systems (ring or C-arm) deliver therapeutic radiation at set angles defined by the rotational trajectory of the radiation source. In a robotic arm-based system, the therapeutic radiation source is mounted on an articulated robotic arm that extends over and around the patient, and the robotic arm is configured to provide at least five degrees of freedom. The robotic arm based system provides the capability of delivering therapeutic radiation from multiple out-of-plane directions, i.e. non-coplanar delivery.

[0006] Each radiation therapy system is associated with an imaging system that provides intra-treatment images used to set up and, in some embodiments, guide the radiation delivery procedure and track the target's movement during treatment. The MV imaging system may place a detector opposite the treatment source to image the patient for set-up and intra-treatment images, while other approaches utilize a separate and independent imaging radiation source or sources and / or detector or detectors for patient set-up and intra-treatment images. Tracking of the target or target volume during treatment is achieved by comparing the intra-treatment images with prior 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 any information derived from these imaging modalities (e.g., but not limited to, digitally reconstructed simulated images (DRR)).

[0007] In one common scenario, the treatment source is a LINAC that generates treatment radiation (which may be, for example, an MV source), and the imaging system comprises one or more independent X-ray imaging sources that generate lower energy imaging radiation (each of which may be, for example, a kV source). The intra-treatment image may include one or more (preferably at least two) two-dimensional images (typically X-rays) acquired at one or more different viewpoints (e.g., a stereoscopic X-ray image). This may be compared, for example, to a two-dimensional DRR derived from the three-dimensional pre-treatment image information. The DRR is a synthetic X-ray image generated by projecting a virtual X-ray through the 3D imaging data. In this case, the direction and orientation of the virtual X-ray simulates the geometry of the intra-treatment X-ray imaging system. The resulting DRR then has approximately the same scale and viewpoint as the intra-treatment X-ray imaging system and can be compared to the intra-treatment X-ray image to determine the location and orientation of the target. This may then be used to guide the delivery of radiation to the target.

[0008] In another common scenario, either a gantry-mounted therapeutic radiation source or a separate x-ray imaging source (e.g., kV source) is used to acquire multiple fields of view and reconstruct volumetric images, i.e., CT images. The views, also called projections, are acquired with the imaging beam fan angle at least 180 degrees to provide full mathematical support for reconstructing a 3D volume or individual axial slices. The imaging detector mounted on the opposite side of the x-ray source can be a single-row detector used to acquire data for a single slice at a time, or a multi-row detector or full 2D panel detector to acquire data for many slices at once.

[0009] Typically, there are two goals in radiation therapy: (i) to deliver a highly conformal dose distribution to the target volume (matching the radiation delivery / dose to the target shape by utilizing CT imaging, sparing healthy tissue as much as possible), and (ii) to deliver the treatment beam with high precision throughout the entire treatment. The third goal is to achieve the two general goals in the least amount of time per portion possible. Delivery of a more conformal dose distribution may require, for example, the ability to deliver a non-coplanar beam. Accurate delivery of the treatment beam requires the ability to track the position of the target volume. The ability to increase the delivery speed requires the ability to move the radiation source accurately, precisely, and quickly without colliding with other objects or the patient in the room and / or violating speed limitations imposed by regulatory agencies.

[0010] Ring gantry-based systems exhibit relatively high mechanical stability and are capable of reproducibly and accurately positioning the radiation source, including at relatively high mechanical drive speeds, thereby avoiding some of the limitations exhibited by robotic and / or C-arm gantry-based systems.

[0011] Regarding intra-treatment imaging, X-ray tomosynthesis has been proposed as an intra-treatment kV imaging diagnostic tool for use in conjunction with a radiation therapy system. X-ray tomosynthesis refers to the process of acquiring a large number of two-dimensional X-ray projection images of a target volume using a relatively large number of X-rays projecting onto the target volume at different angles, followed by mathematical processing of the two-dimensional X-ray projection images to obtain a series of one or more tomosynthesis reconstructed images representing one or more slices of the target volume. The set of X-ray projection images is smaller than that which would be required for CT image reconstruction, and / or the number or range of incident radiation angles is smaller than that which would be used in a CT imaging procedure. In general, multiple tomosynthesis reconstructed images are created, each of which represents a different slice of the target volume. Thus, the series of tomosynthesis reconstructed images may be 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.

[0012] 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 for constructing the tomosynthesis image are taken over an angular range between 1 degree and an angular range value less than that required for a complete projection set for CT imaging (e.g., 180 degrees plus the fan angle). The number of projection images generated in this range is between 2 and 1000. In other preferred embodiments, the x-ray projection images for constructing the tomosynthesis image are taken over an angular range between 5 degrees and 45 degrees. The number of projection images generated in this range is between 5 and 100.

[0013] U.S. Patent No. 6,778,850, incorporated herein by reference, discloses the use of X-ray tomosynthesis images as an intra-treatment kV imaging diagnostic tool, and more particularly, the use of intra-treatment 3D images of a target region of relatively low clarity synthesized from multiple 2D diagnostic images acquired at different angles.

[0014] CBCT has also been proposed as an intra-treatment imaging modality for use in conjunction with radiation therapy systems, in some cases as a kV imaging modality and in other cases as a MV (portal) imaging modality. Whereas conventional CT imaging reconstructs 2D slices from 1D projections through the target volume, which are then stacked to form a 3D volumetric image, CBCT imaging constructs a 3D volumetric image directly from 2D projections of the target volume. CBCT offers the ability to form a 3D image volume from a single gantry rotation (more specifically, at least 180 degrees of rotation plus a fan beam angle) around the target volume. Conventional CT, on the other hand, requires additional rotations to form a similar 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 offers a more isotropic spatial resolution. Conventional CT, on the other hand, limits spatial resolution in the longitudinal direction to the slice thickness. However, scatter noise and artifacts are a greater challenge for CBCT systems than for conventional CT systems because conventional CT systems typically offer substantially higher collimation angles near their linear or quasi-linear row detectors than can typically be offered by CBCT systems near their own two-dimensional detectors. Furthermore, a major issue with single rotation CBCT (other than scatter) is inadequate sampling in all slices except the central slice (the slice that contains the rotation).

[0015] Pre-treatment treatment planning images can be acquired for treatment planning. Then, before each treatment session, CBCT images can be acquired and compared to the pre-treatment treatment planning images. The comparison results are used to modify the treatment plan during treatment, for example to correct for set-up errors and / or organ motion between treatments. By limiting the allowable C-arm gantry rotation speed (e.g., 1 revolution per minute), which makes the CBCT acquisition time slow compared to the patient's respiration (or other physiological cycle), a gating scheme synchronized to the patient's respiration (or other physiological cycle) can be used during CBCT acquisition to reduce the deleterious effects of organ motion in the reconstructed images. Also, due to the relatively slow CBCT acquisition time, CBCT volume data is generally only useful for patient set-up before each treatment session, and not for postural correction.

[0016] No. 9,687,200, incorporated herein by reference, discloses the use of a translatable ring gantry for radiation treatment. An IGRT machine is provided that includes a ring gantry having a central opening and a radiation treatment head coupled to the ring gantry that is rotatable about the central opening through an arc of at least 180 degrees.

[0017] One or more problems arise with known medical imaging and / or radiation therapy systems that are at least partially addressed by one or more embodiments further described herein below, such as increasing the accuracy of spatial registration between image sets to enable more precise radiation therapy delivery, reducing image artifacts (e.g., scatter, metal and beam hardening, image blur, motion, etc.), and utilizing dual energy imaging (e.g., material separation and quantitative imaging, patient setup, online adaptive IGRT, etc.). [Prior art documents] [Patent documents]

[0018] [Patent Document 1] U.S. Patent No. 6,778,850 [Patent Document 2] U.S. Patent No. 9,687,200 Summary of the Invention

[0019] In one embodiment, a multi-modal imaging device includes a rotatable gantry system positioned at least partially around a patient support, a first radiation source coupled to the rotatable gantry system and configured for imaging radiation, a second radiation source coupled to the rotatable gantry system and configured for at least one of imaging radiation or therapeutic radiation and having a higher energy level than 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 includes more attenuation than second measured projection data from the second radiation source, and 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 one or more other embodiments in the same or similar manner and / or in combination with or in place of features of the other embodiments.

[0021] The description of the invention is not intended to limit in any way the words used in the claims or the scope of the claims or the invention. Terms used in the claims have all of their full ordinary meanings.

[0022] In the accompanying drawings, which are incorporated in and constitute a part of this specification, embodiments of the present specification are illustrated, and together with the general description of the present invention provided above and the detailed description provided below, they contribute to illustrating embodiments of the present invention. It will be understood that the ranges of elements illustrated in the figures (e.g., boxes, groups of boxes, or other shapes) represent one embodiment of the ranges. In some embodiments, an element may be designed as multiple elements. Or multiple elements may be designed as one element. In some embodiments, an element shown as an internal component of another component may be implemented as an external component, and vice versa. Furthermore, the elements may not be drawn to scale. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a perspective view of an exemplary multi-modal radiation therapy device in accordance with one aspect of the disclosed technique. [Diagram 2] FIG. 1 is a schematic diagram of an exemplary multi-modal radiation therapy device in accordance with one aspect of the disclosed technique. [Diagram 3] 1 illustrates an exemplary radiation treatment environment. [Figure 4] 1 shows an illustration of an exemplary multi-modal scanning configuration. [Diagram 5] 13 shows an illustration of another exemplary multi-modal scanning configuration. [Figure 6] 1 shows an illustration of an exemplary diagnostic procedure of a multi-modal scanning configuration in an overlay view. [Figure 7] 7 illustrates an illustration of a zoomed-in portion of the target shown in FIG. 6. [Figure 8] 1 is a flow chart depicting an exemplary method for combining scan data from multiple radiological diagnostic modalities. [Figure 9] 1 is a flow chart depicting an exemplary method for combining scan data from multiple radiological modalities for scatter correction. [Figure 10]1 is a flow chart depicting an exemplary method for combining scan data from multiple radiological modalities for metal and beam hardening artifact reduction. [Figure 11] 4 is a flow chart depicting an exemplary method for combining scan data from multiple radiological modalities for time resolution correction. [Figure 12] 1 is a flow chart depicting an exemplary method for combining scan data from multiple radiological modalities for motion artifact correction. [Figure 13] 1 is a flow chart depicting an exemplary method for combining scan data from multiple radiological diagnostic modalities for material separation and / or quantitative imaging. [Figure 14] 1 is a flow chart illustrating an exemplary method for combining scan data from multiple radiological diagnostic modalities for patient setup. [Figure 15] 1 is a flow chart depicting an exemplary method for combining scan data from multiple radiological modalities for online adaptive IGRT. [Figure 16] 1 is a flow chart illustrating an exemplary method of IGRT using a radiation therapy device. [Figure 17] FIG. 13 is a block diagram depicting exemplary image-based pre-delivery steps / options. [Figure 18] FIG. 1 is a block diagram representing exemplary data sources that may be utilized during imaging and / or subsequent image-based pre-delivery steps. [Figure 19] 1 is a flow chart illustrating an exemplary method including patient setup or alignment with a radiation therapy device. [Figure 20] 1 is a flow chart illustrating an exemplary method including adaptive IGRT using a radiation therapy device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The following include definitions of exemplary terms that may be used throughout this disclosure: Both the singular and plural forms of all words are within the scope of each meaning.

[0025] As used herein, a "component" may be defined as a portion of hardware, a portion of software, or a combination thereof. A portion of hardware includes at least a processor and a portion of memory, which includes instructions for execution. A component may be associated with an apparatus.

[0026] As used herein, "logic," which is synonymous with "circuitry," includes, but is not limited to, hardware, firmware, software, and / or combinations of each for performing one or more functions or one or more operations. For example, based on a desired application or need, logic may include discrete logic such as a software controlled microprocessor, an application specific integrated circuit (ASIC), or other programmed logic device and / or controller. Logic may also be embodied entirely as software.

[0027] As used herein, a "processor" includes, but is not limited to, one or more of substantially any number of processor systems, such as microprocessors, microcontrollers, central processing units (CPUs), and digital signal processors (DSPs), in any combination, or stand-alone processors. A processor may be associated with various other circuits that support the operation of the processor, such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), clocks, decoders, memory controllers, or interrupt controllers. These support circuits may be internal or external to the processor or its associated electronic package. The support circuits are in operative communication with the processor. The support circuits are not necessarily shown in block diagrams or other diagrams as separate from the processor.

[0028] As used herein, a "signal" includes, but is not limited to, an analog or digital signal, one or more electrical signals containing one or more computer instructions, a bit or bitstream, or the like.

[0029] 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 a function, act, and / or operate in a desired manner. Instructions may be embodied in various forms, such as routines, algorithms, modules, or programs with specific applications, or may be coded from dynamically linked sources or libraries.

[0030] Although exemplary definitions are provided above, it is Applicant's intention that these and other terms be given the broadest reasonable interpretation consistent with this specification.

[0031] As described in more detail below, embodiments of the disclosed approach relate to multimodal imaging / radiation therapy devices and methods. In some embodiments, the radiation therapy delivery devices and methods can utilize an integrated low-energy radiation source for imaging and a high-energy radiation source for therapy and / or imaging in conjunction with or as part of IGRT. In particular, for example, the radiation therapy delivery devices and methods can use rotational (e.g., helical or step-and-shoot) image acquisition in conjunction with a high-energy radiation source for therapy treatment, combined with a low-energy focused radiation source for imaging at the gantry. Complementary information and advantages can be utilized from low-energy radiation sources (e.g., kV) and from high-energy radiation sources (e.g., MV). For example, the inherent contrast of soft tissues can be higher at low energy, whereas at high energy there is no depletion of primary photons through extensive or dense structures. To obtain higher quality images, KV imaging data and MV imaging data can be used to complement each other. High quality volumetric imaging can be required for visualization of targets and organs at risk (OARS) for adaptive therapy monitoring purposes and for treatment planning / treatment replanning purposes. In some embodiments, the multi-modal system may also be used for localization, motion tracking and / or characterization or correction capabilities.

[0032] Image acquisition techniques can include, but are not limited to, multiple rotational scans, which can be, for example, continuous (e.g., having a helical source trajectory about a central axis with longitudinal movement of the patient support through the gantry bore), non-continuous stop-and-reverse circumferential scans with incremental longitudinal movement of the patient support, step-and-shoot circumferential scans, etc.

[0033] In connection with various embodiments, the multimodal device focuses the radiation source, for example using a beamformer (which may include a collimator) to limit the beam, for example into a cone beam or fan beam. In one embodiment, the focused beam is combined with a gantry that rotates continuously while the patient moves, thereby allowing for helical image acquisition.

[0034] In some embodiments, the time associated with increased scan rotations to complete a high quality volumetric image can be reduced by using high gantry rates / speeds (e.g., using high speed slip ring rotation, including, e.g., up to 10 revolutions per minute (rpm), up to 20 rpm, up to 60 rpm, or more rpm), 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 pitch, and / or dynamic collimation are additional features in various embodiments. This includes selectively irradiating portions of the detector and selectively defining the active readout region.

[0035] Multimodal devices and methods can provide selective and variable collimation of a radiation beam emitted by a source of radiation, including adjusting the shape of the radiation beam to irradiate 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). Furthermore, by only exposing the primary region of the detector to direct radiation, the shadow region of the detector can receive only scatter. In some embodiments, scatter measurements in the shadow region of the detector (and in some embodiments, measurements in the peripheral region) can be used to evaluate scatter in the primary region of the detector receiving the projection data.

[0036] The multimodal device and method provide selective and variable detector readout area and range, including adjusting the detector readout range to limit the effective area of ​​the detector for improved readout speed. For example, less data than the available shadow area can be read out and used for scatter evaluation. Combining selective readout with beamforming allows for various optimizations of scatter fitting techniques.

[0037] With reference to Figures 1 and 2, a multimodal device 10 is shown. The multimodal device 10 may be associated with and / or incorporated into a radiation therapy device (as shown in Figure 2). It will be appreciated that it may be used for a variety of applications including, but not limited to, IGRT, for example, as an IGRT delivery system (e.g., IGRT delivery system 104 shown in Figure 3 and described in detail below). The multimodal device 10 includes a rotatable gantry system, referred to as a gantry 12, supported or otherwise housed by a support unit or housing 14. Gantry herein refers to a gantry system that includes one or more gantries (e.g., rings or C-arms) that may support one or more radiation sources and / or associated detectors as they rotate around a target. 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, multiple radiation sources and one or more associated detectors can be mounted on the same gantry of a gantry system. This includes, for example, when the gantry system consists of only one gantry. Various combinations of gantries, radiation sources, and radiation detectors can be combined into various gantry system configurations for imaging and / or treating the same volume within the same device. For example, kV radiation sources and MV radiation sources can be mounted on the same or different gantry of a gantry system and selectively used to image and / or treat as part of an IGRT system. When mounted on different gantries, the radiation sources can be independently rotatable. However, it is still possible to simultaneously image the same (or nearly the same) volume. The rotatable ring gantry 12 can have a 10 rpm or greater capability as described above. The rotatable gantry 12 defines a gantry bore 16 into and through 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, providing continuous rotation of the radiation source and associated radiation detector(s) while providing sufficient bandwidth for high quality imaging data received by the detector(s). The slip-ring gantry can eliminate gantry rotation in alternating directions for winding and unwinding cables carrying power and signals associated with the device. Such a configuration allows continuous helical tomography, including CBCT, even when incorporated into an IGRT system. As mentioned above, the main problem with single rotation CBCT is insufficient sampling in all slices except the central slice (the slice containing the rotation). This problem can be overcome by cone beam imaging of a helical trajectory.

[0038] The patient support 18 is positioned adjacent to the rotatable gantry 12 and is configured to support a patient for longitudinal movement into and within the rotatable gantry 12, typically in a horizontal position. 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 operatively 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 attached to the rotating gantry for rotation about the patient's longitudinal axis according to a commanded imaging and / or treatment plan. The patient support can also be moved up and down and left and right within a limited range when the patient support is within the bore 16 to adjust the patient position for optimal treatment. As viewed from the front of the gantry 12, axes x, y and z are indicated. The x-axis is horizontal and points to the right, the y-axis points into the gantry plane, and the z-axis is vertical and points up. The x-, y-, and z-axes follow the right-hand rule.

[0039] As shown in FIG. 2, the multimodal device 10 includes a low energy radiation source (e.g., kV) 30 coupled to or otherwise supported by the rotatable gantry 12. In this embodiment, the low energy radiation source 30 is an imaging radiation source that emits a radiation beam (generally shown as 32) for generating high quality images. In this embodiment, the imaging radiation source is an X-ray source 30 that is configured as a kilovoltage (kV) source (e.g., a medical X-ray source having an energy level ranging from about 20 kV to about 150 kV). In one embodiment, the low energy radiation source includes a kiloelectron volt peak photon energy (keV) up to 150 keV. The imaging radiation source can be any type of transmission source suitable for imaging. For example, the imaging radiation source may be, for example, an X-ray source (including those for CT) or other methods that generate photons with sufficient energy and flux (e.g., a gamma ray source (e.g., Cobalt-57, energy peak at 122 keV), an X-ray fluorescence source (e.g., a Pb k-ray passing fluorescence source, two peaks at about 70 keV and about 82 keV), etc.). References herein to X-ray, X-ray imaging, X-ray imaging sources, etc. are exemplary for certain embodiments. Other imaging transmission sources may be used interchangeably in various other embodiments. An X-ray detector 34 (e.g., a two-dimensional flat 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 is rotatable in conjunction with the X-ray source 30.

[0040] It will be appreciated that the X-ray detector 34 may take on numerous configurations without departing from the scope of the disclosed techniques. As illustrated in FIG. 2, the X-ray detector 34 may be configured as a flat panel detector (e.g., a multi-slice flat panel detector). According to another exemplary embodiment, the X-ray detector 34 may be configured as a curved detector. The detector 34 may detect or measure the amount of unattenuated radiation. Thus, it is possible to infer what was actually attenuated by the patient or the associated patient ROI (compared to that originally generated). The detector 34 may detect or otherwise collect attenuation data from different angles as the low energy radiation source 30 rotates around and emits radiation to the patient.

[0041] Although FIGS. 1 and 2 depict a multimodal device 10 having a radiation source 30 mounted on a ring gantry 12, other embodiments may include other types of rotatable imaging devices, including, for example, C-arm gantry and robotic arm based systems. In a gantry based system, the gantry rotates the imaging radiation source 30 around an axis passing through the isocenter. The gantry based system includes a C-arm gantry, in which the imaging radiation source 30 is mounted in a cantilever-like manner and rotates around an axis passing through the isocenter. The gantry based system further includes a ring gantry, for example the rotatable gantry 12, which generally has an annular shape in which the patient's body extends through the bore of the ring / toroid. Also, the imaging radiation source 30 is mounted on the ring circumference and rotates around 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 rotates and counter-rotates repeatedly.

[0042] A collimator or beamformer assembly (generally shown 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 irradiate locations or areas of the active area of ​​the x-ray detector 34. The beamformer can also control how the radiation beam 32 is positioned on the x-ray detector 34. In one embodiment, the beamformer 36 may have a single degree / dimension of motion (e.g., to create thinner or thicker slits). In another embodiment, the beamformer 36 may have two degrees / dimensions of motion (e.g., to create variously sized rectangles). In other embodiments, the beamformer 36 may have the capability of a variety of other dynamically controlled shapes, including, for example, a parallelogram. All of these shapes may be dynamically adjusted during a scan. In some embodiments, blocking portions of the beamformer may be rotated and / or translated.

[0043] The beamformer 36 can be controlled to dynamically adjust the shape of the radiation beam 32 emitted by the x-ray source 30 in many geometries, including but not limited to fan beams or cone beams having low beam thicknesses (widths) as well as those including single row detectors or multi-row detectors (which may only be a fraction of the active area of ​​the detector). In various embodiments, the beam thickness may illuminate several centimeters of the active area of ​​a larger detector. For example, of a 5-6 centimeter detector, 3-4 centimeters (measured in the long direction of the detector face) may be selectively illuminated with imaging radiation 32. In this embodiment, 3-4 centimeters of projection image data may be captured using approximately 1-2 centimeters of non-illuminated detector area on one or each side, which may be used to capture scatter data with respective readings, as described below.

[0044] In other embodiments, a majority of the active detector may be selectively exposed to imaging radiation. For example, in some embodiments, the beam thickness may be reduced to about 2 centimeters, about 1 centimeter, less than 1 centimeter, or a similar size range. This includes smaller detectors. In other embodiments, the beam thickness may be increased to about 4 centimeters, about 5 centimeters, more than 5 centimeters, or a similar size range. This includes larger detectors. In various embodiments, the ratio of illumination to active detector area may be 30-90%, or 50-75%. In other embodiments, the ratio of illumination to active detector area may be 60-70%, although various other illumination area and active area sizes or ratios of illumination to active detector area may be suitable in other embodiments. The beam and detector may be configured such that the shadow area (active but not directly exposed to radiation) of the detector is sufficient to capture scatter data beyond the edge area.

[0045] Various embodiments may include optimizing the features that control the selective illumination of the detector (e.g., beam size, beam / aperture center, collimation, collimation, pitch, detector readout range, detector readout center, etc.) so that measurement data is sufficient for primary (illuminated) and shadow regions, but also optimized for speed and dose control. The shape / position of the beamformer 36 and the readout range of the detector 34 may be controlled so that the radiation beam 32 from the x-ray source 30 ranges a comparable or smaller x-ray detector 34 based on the particular imaging task and scatter evaluation process being performed, including, for example, a combination of narrow and wide axial field of view (aFOV) scans. The instrument 10 has the capability of acquiring both single rotation cone beam images, and wide and narrow beam angle images, helical or otherwise.

[0046] The beamformer 36 may be configured in a variety of ways that allow the beamformer 36 to adjust the shape of the radiation beam 32 emitted by the x-ray source 30. For example, the beamformer 36 may be configured to include a series of jaws or other suitable members that define and selectively adjust the size of an aperture through which the radiation beam from the x-ray source 30 may pass in a focused manner. In accordance with one exemplary configuration, the beamformer 36 may include upper and lower jaws that are movable in different directions (e.g., parallel directions) to adjust the size of the aperture through which the radiation beam from the x-ray source 30 passes, and also adjust the position of the beam 32 relative to the patient to irradiate only a portion of the patient being imaged for optimized imaging and minimized patient dose.

[0047] According to one embodiment, the shape of the radiation beam 32 from the X-ray source 30 may be altered during image acquisition. Stated differently, according to one exemplary embodiment, the leaf position and / or aperture width of the beamformer 36 may be adjusted before or during a scan. For example, according to one embodiment, the beamformer 36 may be selectively controlled and dynamically adjusted during rotation of the X-ray source 30 such that the radiation beam 32 has a shape with sufficient primary / shadow regions and is adjusted to include only the subject of interest (e.g., the prostate) during imaging. The shape of the radiation beam 32 emitted by the X-ray source 30 may be altered during or after a scan depending on the desired image acquisition. This may be based on imaging feedback and / or therapeutic feedback, as described in more detail below.

[0048] As shown in FIG. 2, the multimodal device 10 may be integrated with a radiation therapy device including a high energy radiation source (e.g., MV) 20 coupled to or otherwise supported by the rotatable gantry 12. According to one embodiment, the high energy radiation source 20 is configured as a therapeutic radiation source, such as a high energy radiation source used to treat a tumor inside a patient within a region of interest. In other embodiments, the high energy radiation source 20 is also configured as or at least utilized as an imaging radiation source. It will be understood that the therapeutic radiation source may be a high energy X-ray beam (e.g., MV X-ray beam), and / or a high energy particle beam (e.g., an electron beam, a photon beam, or a beam of heavy ions such as carbon) or another suitable form of high energy radiation. In one embodiment, the high energy radiation source 20 includes a megaelectron 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. Generally, the high energy radiation source 20 has a higher energy level (e.g., peak and / or average) than the low energy radiation source 30.

[0049] In one embodiment, the high energy radiation source 20 is a LINAC that generates therapeutic radiation (e.g., MV), and the imaging system includes a separate low energy radiation source 30 that generates relatively low intensity, low energy imaging radiation (e.g., kV). In other embodiments, the therapeutic radiation source 20 may be a radioisotope, such as Co-60, that may typically have an energy greater than 1 MeV. The high energy radiation source 20 is capable of emitting one or more radiation beams (generally indicated by 22) to a region of interest (ROI) within a patient supported on a patient support 18 according to a treatment plan.

[0050] In various embodiments, the high-energy radiation source 20 is utilized as a therapeutic radiation source and an imaging radiation source. As described in detail below, the radiation sources 20, 30 may be used in conjunction with one another to provide high quality and better utilization images. References herein to the therapeutic radiation source 20 are intended to distinguish between the high-energy radiation source 20 and the low-energy radiation source 30, which may 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) may be utilized for treatment and / or imaging. In other embodiments, at least one additional radiation source may be coupled to the rotatable gantry 12 and operated to acquire projection data at a peak photon energy other than the peak photon energy of the radiation sources 20, 30.

[0051] The detector 24 may be coupled to or otherwise supported by the rotatable gantry 12 and positioned to receive radiation 22 from the therapeutic radiation source 20. The detector 24 may detect or measure the amount of unattenuated radiation. Thus, it is possible to infer what was actually attenuated by the patient or the associated patient ROI (compared to that originally generated). The detector 24 may detect or otherwise collect attenuation data from different angles as the therapeutic radiation source 20 rotates around and emits radiation to the patient.

[0052] It will be understood that the therapeutic radiation source 20 may include or otherwise be associated with a beamformer or collimator. The beamformer associated with the therapeutic radiation source 20 may be configured in many ways, similar to the beamformer 36 for the imaging source 30. For example, the beamformer may be configured as a multi-leaf collimator (MLC). This may include a plurality of interdigitated leaves operable to move to one or more positions between a minimally open or closed position and a maximally open position. It will be understood that the leaves may be moved to desired positions to obtain a desired shape of the radiation beam emitted by the radiation source. In one embodiment, the MLC allows for sub-millimeter targeting accuracy.

[0053] The therapeutic radiation source 20 may be mounted, configured, and / or moved in the same plane as the imaging source 30 or in a different plane (offset). In some embodiments, scattering caused by simultaneous activation of the radiation sources 20, 30 may be reduced by offsetting the emission planes.

[0054] In other embodiments, scattering can be avoided by inserting activation. For example, for simultaneous multimodal imaging, the acquisition can be simultaneous and do not have simultaneous individual pulses. In another embodiment, the use of shadow-based scattering correction can be used to address issues such as MV scattering in kV detectors.

[0055] When integrated with a radiation therapy machine, the multimodal device 10 can provide images that are used to set up (e.g., align and / or register), plan and / or manage the radiation delivery procedure (treatment). A typical set up is accomplished by comparing the current (in-treatment) image with pre-treatment image information. 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 the devices mentioned above or other imaging diagnostic modalities. In some embodiments, the multimodal device 10 may track the movement of the patient, target or ROI during treatment.

[0056] The reconstruction processor 40 may be operatively coupled to the detector 24 and / or the detector 34. In one embodiment, the reconstruction processor 40 is configured to generate patient images based on radiation from the radiation sources 20, 30 received by the detectors 24, 34. It will be understood that the reconstruction processor 40 may be configured to be used to perform methods described more fully below. The apparatus 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 (e.g., planning images) from prior or otherwise pre-acquired images, treatment plans, and the like.

[0057] The multimodal device 10 may include an operator / user interface 48, in which an operator of the device 10 may interact with or otherwise control the device 10, provide input related to a scan or imaging parameters, and the like. The operator interface 48 may include any suitable input device, such as a keyboard, mouse, voice-activated controller, and the like. The device 10 may also include a display 52 or other human readable element to provide output to an operator of the device 10. For example, the display 52 may enable the operator to observe reconstructed patient images and other information related to the operation of the device 10, such as imaging or scan parameters.

[0058] As shown in FIG. 2, the multimodal device 10 includes a controller (generally shown as 60) operatively coupled to one or more components of the device 10. The controller 60 controls the overall function and operation of the device 10, including providing power and timing signals to the x-ray source 30 and / or therapeutic radiation source 20, as well as a gantry motor controller that controls the rotational speed and position of the rotatable gantry 12. It will be appreciated that the controller 60 can encompass one or more of a patient support controller, a gantry controller, a controller coupled to the therapeutic radiation source 20 and / or x-ray source 30, a beamformer controller, a controller coupled to the detector 24 and / or x-ray detector 34, etc. In one embodiment, the controller 60 is a system controller capable of controlling other components, devices and / or controllers.

[0059] In various embodiments, the reconstruction processor 40, the operator interface 48, the display 52, the controller 60, and / or other components may be combined into one or more components or devices.

[0060] 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 multimodal device and / or radiation therapy system may include various other devices and components (e.g., gantry, radiation source, collimator, detector, controller, power supply, patient support, among others) capable of performing one or more routines or steps related to imaging and / or IGRT for a particular application. Routines may include imaging, image-based pre-delivery steps, and / or treatment delivery including settings, configurations, and / or positions (e.g., paths / trajectories) of individual devices, which may be stored in memory. Furthermore, one or more controllers may directly or indirectly control one or more devices and / or components according to one or more routines or processes stored in the memory. An example of direct control is the setting of various radiation source or collimator parameters (power, speed, position, timing, adjustment, etc.) related to imaging or treatment. An example of indirect control is the communication of positions, paths, speeds, etc. to a controller of a patient support or other peripheral devices. The hierarchy of the various controllers that may be associated with the device may be arranged in any suitable manner to convey appropriate commands and / or information to the desired devices and components.

[0061] In addition, those skilled in the art will appreciate that the system and method may be implemented in other computer system configurations. 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 connected through 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 both local and remote memory storage devices. For example, a remote database, a local database, a cloud computing platform, a cloud database, or a combination thereof may be utilized with the device 10.

[0062] The multimodal device 10 can utilize an exemplary environment for implementing various aspects of the present invention, including a computer. The computer includes a controller 60 (including a processor and memory, which may be memory 44, for example) and a system bus. The system bus can couple to system components, including but not limited to memory to the processor, and can communicate with other systems, controllers, components, devices, and processors. The memory can include read-only memory (ROM), random access memory (RAM), hard drives, flash drives, and other forms of computer-readable media. The memory can store various software, including routines and parameters, and data, which may include, for example, a treatment plan.

[0063] 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 by and operated simultaneously with the therapeutic radiation source 20. Additionally or alternatively, the X-ray source 30 may be controlled by and operated sequentially with the therapeutic radiation source 20 depending on the particular treatment and / or imaging plan being performed. For example, in various embodiments, the radiation sources 20, 30 may be operated such that measured projection data from the radiation sources 20, 30 are acquired simultaneously (or essentially / nearly (to some degree) simultaneously, e.g., within about 50 ms of each other) or sequentially (e.g., separated by seconds, minutes, etc.).

[0064] It will be appreciated that the radiation source 20, 30 and the one or more detectors 24, 34 may be configured to provide rotation around the patient during imaging and / or treatment scanning in many ways. In one embodiment, the movement and irradiation of the radiation source 20, 30 may be synchronized with the longitudinal movement of the patient support 18 to provide continuous helical acquisition or scanning of patient images during treatment. In addition to continuous rotation of the radiation source 20, 30 and the one or more detectors 24, 34 (e.g., continuous and constant rotation of the gantry with a continuous patient motion speed), it will be appreciated that other variations may be used without departing from the scope of the disclosed techniques. For example, the rotatable gantry 12 and patient support may be controlled such that the gantry 12 rotates around a patient supported on the patient support in a "reciprocating" manner (e.g., alternating clockwise and counterclockwise rotations) as 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, continuous step-and-shoot circumferential scanning is used, where movement of the patient support 18 in the longitudinal direction (step) is alternated with scanning rotation by the rotatable gantry 12 (shoot) until the desired volume is captured. The multi-modal device 10 has the capability of performing volumetric and planar based image acquisition. For example, in various embodiments, the multi-modal device 10 can be used to acquire volumetric and / or planar images and perform associated processing, including the scatter assessment / scatter correction methods described below.

[0065] Various other types of radiation source and / or patient support movements may be used to obtain relative motion of the radiation source and the patient for generation of projection data. Non-continuous motion of the radiation source and / or patient support, continuous but variable / non-constant (including linear and non-linear) movements, velocities, and / or trajectories, etc., and combinations thereof, may be used, including in combination with various embodiments of the apparatus 10 described above.

[0066] In one embodiment, the rotational speed of the gantry 12, the speed of the patient support 18, the beamformer geometry and / or the detector readings may all be constant during image acquisition, while in other embodiments, one or more of these variables may change dynamically during image acquisition and / or treatment.

[0067] In other embodiments, these features are combined with one or more other image-based actions or procedures, including, for example, patient setup, adaptive therapy monitoring, therapy planning, and the like.

[0068] 3 illustrates an exemplary radiation treatment environment 300. The radiation treatment environment 300 includes a reference imaging system 102 and an IGRT system 104. The IGRT system 104 may include, for example, the multimodal device 10 and its various components and devices described above.

[0069] In one embodiment, the reference imaging system 102 may include a high-precision volumetric imaging system, such as a CT system or an MRI system. In terms of cost and workflow considerations in many clinical environments, the reference imaging system 102 is a general purpose vehicle used for a variety of different purposes in a clinical or hospital environment, and is not specialized to the IGRT system 104 or environment 300. Rather, the reference imaging system 102 may be located in its own individual room or archway and is purchased, installed and / or maintained on a separate, more generalized basis from the IGRT system 104. Thus, in the embodiment of FIG. 3, the reference imaging system 102 is illustrated as being 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 multimodal device 10 has the capability to function as the reference imaging system 102 and the IGRT system 104.

[0070] In this embodiment, the IGRT system 104 comprises a high-energy radiation therapy (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 the therapeutic radiation under the control of a system controller 114, and more particularly, in one embodiment, a therapeutic radiation control subsystem 128. The system controller 114 further comprises processing circuitry 120, a detector controller 122, a couch position controller 124, and a kV radiation controller 126, each programmed and configured to achieve 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 the high-energy X-ray therapeutic radiation from the MV source 108 propagated through the target volume.

[0071] Each kV radiation source 110 and MV radiation source 108 is dynamically movable and therefore has a precisely measurable and / or precisely determinable geometry relative to the (x, y, z) coordinate system of the IGRT system 104 and / or treatment room.

[0072] The couch positioner 130 can be actuated by the couch position controller 124 to position the couch TC. In some embodiments, the non-X-ray based position sensing system 134 detects the position and / or movement of one or more external markers strategically attached to the patient and / or the position and / or movement of the patient's skin surface itself using one or more methods that do not involve ionizing radiation, such as optical-based or ultrasound-based methods. The IGRT system 104 further includes an operator workstation 116 and a treatment planning system 118.

[0073] In typical clinical practice, treatment planning is performed on pre-acquired treatment planning images or pre-image data 106 generated by a reference imaging system 102. The pre-acquired treatment planning images 106 are often high-resolution three-dimensional CT images acquired substantially in advance (e.g., 1-2 days prior) of one or more radiation treatments that the patient will receive. In contrast to the (x, y, z) treatment room coordinate system illustrated for the treatment room of the IGRT system 104, there is generally no pre-existing or inherent alignment or registration between the treatment planning image 106 coordinate system and the treatment room coordinate system, as shown in FIG. 3 by illustrating the (i, j, k) coordinate system of the pre-acquired treatment planning image 106. During the treatment planning process, the physician typically establishes a coordinate system in the treatment planning image (e.g., i, j, k in the treatment planning image 106). This may also be referred to herein as the planning image coordinate system or planning image reference frame. The radiation treatment plan is developed in a planning image coordinate system which determines the various orientations, sizes, durations, etc. of the high energy therapeutic radiation beams applied by the MV source 108 during each treatment session. Accurate delivery of the therapeutic radiation to the target requires alignment of the treatment room coordinate system with the planning image coordinate system, since the entire delivery and tracking system (if present) is calibrated to the treatment room coordinate system. It will be appreciated that this alignment does not need to be precise and couch adjustments or beam delivery adjustments can be used to account for offsets in the alignment between the two coordinate systems.

[0074] In one embodiment, immediately prior to each treatment time, an image-based pre-delivery step may be performed under image guidance by the kV imaging radiation source 110, including according to one or more embodiments further described herein below. For example, the patient may be physically positioned or aligned such that the planning image coordinate system (defined by the physician during treatment planning, for example but not limited to, on a CT image or planning image) is positioned in initial alignment with the treatment room coordinate system, referred to herein as initial treatment alignment or initial treatment position. This alignment is commonly referred to as patient setup or patient alignment. Depending on the location of the target volume, the target volume may change position and orientation and / or undergo volume deformation due to patient movement and / or physiological cycles such as breathing. As used herein, the terms variation in alignment during treatment or variation in position during treatment are used to refer to variations in position, orientation and / or volume shape where the current state of the target volume differs from the initial treatment position alignment. Due to the known relationship between the treatment planning coordinate system and the treatment room coordinate system, the term variation in registration during treatment can also be used to refer to variations in position, orientation, or volume shape where the current state of the target volume differs from that of the treatment planning coordinate system. More generally, the term initial treatment registration or initial treatment position, as used herein, refers to a particular physical posture or arrangement (including position, orientation, and volume shape) of a patient's body parts during patient setup, at the start of treatment.

[0075] A non-X-ray based position sensing system 134 may also be provided. This may include, for example, an external marker affixed in some manner to the patient's chest that moves in response to breathing. This may precisely determine the target location. 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 position positioning, EKG for cardiac gating, etc. The system 134 may correlate the movement of the external marker with the movement of the target, as determined, for example, by monocular or stereoscopic X-ray projection. The non-X-ray based position sensing system 134 thus allows the system controller 114 to monitor the movement of the external marker and use a correlation model to precisely predict in real time (e.g., ∼60 Hz) where the target will be located and direct the treatment beam to the target. As treatment of the moving target progresses, additional X-ray images may be acquired and used to validate and update the correlation model.

[0076] As used herein, "registration" of medical images refers to the determination of mathematical relationships of corresponding anatomical or other (e.g., fiducial) features occurring in those medical images. Registration can include, but is not limited to, the determination of one or more spatial transformations that, when applied to one or both of the medical images, cause overlay of corresponding anatomical features. The spatial transformations can include rigid and / or deformable transformations. Also, differences in the coordinate systems or reference frames can be taken into account if the medical images are from different coordinate systems or reference frames. If the medical images are not acquired using the same imaging system and are not acquired simultaneously, the registration process can include, but is not limited to, both the determination of a first transformation that takes into account differences between the imaging modalities, imaging geometries, and / or reference frames of the different imaging systems, and the determination of a second transformation that takes into account underlying anatomical differences in the body part that occurred between acquisition times (e.g., positioning differences, global translation, relative motion between different structures within the body part, global deformation, local deformation within the body part, etc.).

[0077] Image registration may be performed between the reference imaging system 102 and the IGRT delivery system 104, and / or between data and / or images derived from various diagnostic modalities of the multi-modal IGRT delivery system 104, including one or more low-energy radiation sources 110 and high-energy radiation sources 108 (and their associated detectors 112). In particular, referring back to the apparatus 10, registration may be performed between data and / or images derived from the radiation sources 20, 30 and the detectors 24, 34.

[0078] In one embodiment, FIG. 4 shows a diagram of an exemplary multi-modal scanning configuration 400. Looking at the front of the ring gantry 410, FIG. 4 shows a high-energy radiation source 420 (e.g., MV) and a low-energy radiation source 430 (e.g., kV) mounted on the ring gantry 410. Although the radiation sources 420, 430 are shown mounted orthogonal to each other, other embodiments may include other angular relationships as well as additional radiation sources and / or detectors. The high-energy radiation source 420 is shown projecting radiation by a beamformer 426 to generate a radiation beam 422 that projects onto a portion of the detector 424. In this configuration, the high-energy radiation source 420 has a transaxial field of view (FOV) 428. The low-energy radiation source 430 is shown projecting radiation by a beamformer 436 to generate a radiation beam 432 that projects onto a portion of the detector 434. In this configuration, the low-energy radiation source 430 has a transaxial FOV 438. Detector 434 is shown centered within its range 435. In this manner, radiation sources 420, 430 project radiation through overlapping transaxial FOVs. In this embodiment, multi-modal scanning configuration 400 exhibits a high-energy FOV 428 having a larger transaxial FOV than a low-energy FOV 438.

[0079] In another embodiment, FIG. 5 shows an illustration of an exemplary multimodal scanning configuration 500. Looking at the front of the ring gantry 410, FIG. 5 also shows a high-energy radiation source 420 and a low-energy radiation source 430 mounted orthogonally to the ring gantry 410. The high-energy radiation source 420 is shown projecting radiation by a beamformer 526 to generate a radiation beam 522 that projects to a detector 524. In this configuration, the high-energy radiation source 420 has a transaxial FOV 528. The low-energy radiation source 430 is shown projecting radiation by a beamformer 536 to generate a radiation beam 532 that projects to an offset detector 534. In this configuration, the low-energy radiation source 430 has a transaxial FOV 538 with at least 180 degrees of rotation. In this manner, the radiation sources 420, 430 also project radiation through overlapping transaxial FOVs. In this embodiment, the multi-modal scanning configuration 500 exhibits a low-energy FOV 538 that has a larger transaxial FOV than the high-energy FOV 528 .

[0080] For example, various factors can be used to control the FOV (e.g., transaxial and axial) of each of the radiation sources including beamformer configuration, radiation source angle, detector position, etc. In some embodiments, the radiation sources 420, 430 may be physically offset longitudinally (along the y-axis) and may scan the patient at different times (offset in time).

[0081] In another embodiment, FIG. 6 shows an illustration of an exemplary diagnostic procedure of a multimodal scanning configuration 600 with superimposed views. Looking at the side of a ring gantry (not shown), FIG. 6 shows the positions of a high-energy radiation source 620 (e.g., MV) and a low-energy radiation source 630 (e.g., kV) superimposed onto the same plane of a target 615. The radiation sources 620, 630 are typically not mounted relative to each other and may be mounted on the gantry 90 degrees apart, but are shown superimposed in FIG. 6 to show an exemplary overlap of their respective views and features. Other embodiments can include other angular relationships as well as additional radiation sources. The high-energy radiation source 620 is shown to project radiation by a beamformer 626 to generate a radiation beam 622 that projects onto a detector 624. In this configuration, the high-energy radiation source 620 has a body axis FOV 628. The low-energy radiation source 630 is shown to project radiation by a beamformer 636 to generate a radiation beam 632 that projects onto a portion of the detector 634. In this configuration, the low-energy radiation source 630 has a body axial FOV 638. The detector 634 receives the direct projections and is shown having an active area 634a and a shadow area 634b blocked from the direct radiation by the beamformer 636. In this manner, the radiation sources 620, 630 project radiation through overlapping body axial FOVs. In this embodiment, the multi-modal scanning configuration 600 exhibits a low-energy FOV 638 that has a larger body axial FOV than the high-energy FOV 628.

[0082] FIG. 7 illustrates a zoomed-in portion 700 of the target 615 shown in FIG. 6. 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, where the low-energy FOV 638 provides imaging data beyond the high-energy FOV 628, shown as region 740. However, in other embodiments, the high-energy FOV 628 can provide imaging data beyond the low-energy FOV 638, as described above. In some embodiments, the FOVs 628, 638 can be the same (e.g., transaxial and / or axial). Additionally, in further embodiments, the FOVs 628, 638 can be adjacent but non-overlapping, have a space between them, be grouped such that one FOV is within the other without overlapping, or a combination thereof.

[0083] In some embodiments, one or more radiation sources may be used for sparse data and may utilize different resolutions, speeds, trajectories, frequencies, power levels, doses, FOVs, etc. In any case, data from two or more radiological modalities may be used in combination to improve image quality, speed, dose, workflow, treatment accuracy / precision, etc.

[0084] In various embodiments, the exemplary scanning configurations 400 , 500 , 600 described above may be implemented using the multi-modal device 10 , including via the radiation treatment environment 300 .

[0085] The following flow charts and block diagrams illustrate example configurations and methodologies associated with the multimodal radiation system described above. The example methodologies may be implemented in logic, software, hardware, or combinations thereof. Additionally, although the procedures and methods are depicted in sequence, the blocks may be executed in different orders, including serial and / or parallel. Furthermore, additional or fewer steps may be used.

[0086] FIG. 8 is a flow chart depicting an exemplary method 800 of combining scan data from multiple radiological diagnostic modalities, such as those described above. In step 805, pre-image data 805 may be provided. In step 810, the method 800 determines a scan configuration, including a scan design for each diagnostic modality of the multimodal system. Then, in 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 generates low-energy scan data 830 and high-energy scan data 832. Then, in step 840, the method 400 utilizes or combines the low-energy scan data 830 and the high-energy scan data 832. Then, in 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 associated scan design may be configured such that at least one of the scan data 830, 832 complements or supplements another of the scan data 830, 832 from the different diagnostic modalities, resulting in at least one of the improvements described herein.

[0087] In some embodiments, the scan configuration includes a helical scan trajectory. The geometry of helical fan-beam MV (high energy) CT (MVCT) acquisition can provide multiple advantages, including, for example, a wide transverse image (e.g., about 40 cm at isocenter), complete Fourier sampling of the volume of interest, and reduced scattering in the projection images. These features can improve the quality of the reconstructed image over the clinical state-of-the-art cone-beam MVCT. In particular, for example, these advantages are due to the fan-squeezed MV treatment / imaging beam and the fact that the MV source and detector are mounted on a continuously rotating slip-ring system that allows imaging from all directions, as described above. In operation, the system (e.g., instrument 10) can image continuously over more than 2π radians and move the source and detector in a helical trajectory with respect to the patient on the couch translating without stopping to unwind the cables or use an irregular imaging trajectory.

[0088] In various embodiments, in addition to the helical fan beam MVCT system, a kV (low energy) x-ray source and flat panel detector allows the system to acquire kVCT images with geometries such as helical fan beam, helical narrow cone angle cone beam, and stationary couch, circular orbit fan beam, etc., as described above. Because the kV imaging hardware is mounted to the same slip ring gantry as the MV imaging / treatment hardware (e.g., as shown in Figures 2 and 4-6), the kV imaging system can also utilize a slip ring mounted imaging system as described above, allowing the kV imaging system to operate as a diagnostic CT rather than a positioning CBCT, as found in conventional C-arm systems.

[0089] A further unique advantage of a multimodal (e.g., dual kV / MV) slip-ring mounted imaging system (e.g., instrument 10) is that the systems, mounted together (e.g., orthogonal to one another), can be used to acquire image data that is precisely synchronized in time and space. Both the MV and kV systems can image the same anatomy at the same time to generate a simultaneous acquisition of the patient's anatomy (e.g., as shown in Figures 6-7). This includes 3D information as it changes over time. Although the projection angles of each system may be different, this does not present issues with full CT imaging, such as the symmetry inherent in the object and CT reconstruction. Combined with the high speed imaging speed resulting from the slip-ring mounting, the system can rapidly acquire high temporal resolution kV / MV fan beam images over long axial extents.

[0090] In various embodiments, the multimodal device 10 can include an N-tuple source and detector CT system (where N sources and N or another number of detectors are positioned such that each projection image data can be acquired simultaneously) having a source providing multi-energy (e.g., low-energy and high-energy) projection data. The use of a fan-beam imaging geometry (e.g., using a helical scan trajectory) in combination with a simultaneous multi-energy kV / MV imaging device provides the advantages described herein. Typical existing systems are limited to cone-beam imaging geometries of either kV or MV sources individually. This has significant disadvantages over fan-beam imaging geometries, as discussed above.

[0091] 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, the MV projections can be used as a priori information to correct kVCT artifacts, or can be used in dual-energy CT reconstruction for quantitative imaging and material separation. Furthermore, MLC-modulated MV projection data can be available during treatment to affect kVCT reconstructions concurrent with or after treatment delivery. kV acquisition can occur concurrently with and / or prior to treatment. Electron density images obtained from dual-energy reconstructions can be used in both online and offline dosimetry applications.

[0092] Several problems that arise in known medical imaging and / or radiation therapy systems are at least partially addressed by one or more embodiments described herein, such as increasing the accuracy of spatial registration between image sets to enable more precise radiation therapy delivery, reducing image artifacts (e.g., scatter, metal and beam hardening, image blur, motion, etc.), and utilizing dual energy imaging (e.g., material separation and quantitative imaging, patient setup, online adaptive IGRT, etc.).

[0093] IA

[0094] In some embodiments, a multimodal instrument can be utilized for scatter correction. Referring to the multimodal instrument 10 of FIG. 2, in one embodiment, the flat panel kV detector 34 and the (e.g., xenon gas) MV detector 24 are sensitive to both kV and MV energies. Thus, each detector 24, 34 can measure orthogonal body scatter during irradiation by the other source 20, 30. For example, the MV detector 24 can measure kV scatter over a single but wide detector row. Meanwhile, the kV detector 34 can measure the object's scatter field over an area of, for example, 40 cm×40 cm. In other embodiments, the MV detector 24 need not be single row or wide.

[0095] In some embodiments, a single detector may be used instead of the separate detectors 24, 34. For example, the kV radiation source and the MV radiation source may be placed adjacent to each other on the ring gantry. A detector sensitive to both kV radiation and MV radiation may then be placed on the opposite side of the gantry. The detector may be actuated to move between at least two positions to receive either kV radiation or MV radiation passing through the isocenter of the system, which varies depending on the position of the detector. Alternatively, a wide detector may be used that is wide enough to simultaneously measure radiation from the entirety of both the kV beam and the MV beam. Narrower detectors may also be used, but may only have a limited imaging area from each radiation beam.

[0096] These scatter measurements, potentially with the addition of training data from known objects, can be used to improve scatter correction in the corresponding images. For example, MV scatter is low enough to be ignored in the MVCT image chain, but non-negligible CT inaccuracies and non-uniformities in the MVCT images can be attributed to uncorrected scatter signals. kVCT and especially kV cone beam CT can be affected by much larger scatter signals in the measured projections. MV detector measurements of orthogonal kV scatter can be utilized to better assess and differentiate the scatter contribution from objects in the bore, resulting in improved uniformity and low contrast resolution in the kVCT images.

[0097] For example, FIG. 9 is a flow chart depicting an exemplary method 900 of combining scan data from multiple radiological modalities for scatter correction. Training data 905 from known objects, models, etc. may be provided to refine the process. In some embodiments, a scan configuration (including a scan design for each modality of a multimodal system) may be determined and a scan may be performed according to method steps 810 and 820 of method 800 to generate scan data 930, 932. The low-energy scan data 930 may be, for example, from a low-energy kV scan and may have a relatively high scatter ratio. The high-energy scan data 932 may be, for example, from a high-energy wide-field MV fan beam scan and may have a relatively low scatter ratio. Both projections are within the same transverse plane or planes of the same object scene. In step 940, method 900 utilizes or combines the low-energy scan data 930 and the high-energy scan data 932 by evaluating 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 also provides a "blank" projection or scan in which the kV scatter signal is measured in the absence of MV x-rays. Then, in step 950, the method 900 reconstructs a low-energy kV image using the scatter estimate.

[0098] In some embodiments, the MV projections and the 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 relatively low probability of scattering interactions. In some embodiments, the kV beam 32 forming the kV image has a relatively high probability of scattering interactions. The relative probability can be related to the scattering mechanism (photoelectric effect + Compton vs. Compton only) that fundamentally distinguishes low-energy radiation from high-energy radiation. Only Compton can be applied to high-energy radiation sources (e.g., MV). Low-energy radiation sources (e.g., kV) can also be subject to interactions such as the photoelectric effect.

[0099] IB

[0100] In some embodiments, the multimodal instrument may be utilized for reduction of metal artifacts and beam hardening artifacts. With reference to the multimodal instrument 10 of FIG. 2, in one embodiment, under kV irradiation from the kV source 30, rays from the beam 32 passing through metal (e.g., dental implants or other surgical implants, etc.) or otherwise highly attenuating objects (e.g., dense bone or calcification) may block all or nearly all of the signal from the detector 34 (which preferably attenuates lower energy photons more than higher energy photons) that arrives along the rays passing through the highly attenuating material. This may lead to undefined, highly undefined, and otherwise artifactual measurements by the detector 34 along those rays, which leads to streaking artifacts through the object. Such artifacts are energy dependent such that they are not evident when imaging with higher energy photons from, for example, the MV source 20. For example, a highly attenuated object may block approximately 70% of the kV signal but only about 7% of the MV signal, a difference of approximately 10 times. However, higher energy photons (from MV source 20) have lower intrinsic attenuation contrast in biological tissue than lower energy photons (from kV source 30). To correct for these artifacts while still 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).

[0101] For example, FIG. 10 is a flow chart depicting an exemplary method 1000 of combining scan data from multiple radiological diagnostic modalities for metal and beam hardening artifact reduction. Training data 1005 from known objects, models, etc. may be provided to improve the process. In some embodiments, a scan configuration (including a scan design for each diagnostic modality of the multimodal system) may be determined and a scan may be performed according to method steps 810 and 820 of method 800 to generate scan data 1030, 1032. The low energy scan data 1030 may be, for example, from a low energy kV scan and may have relatively high attenuation dominated by, for example, photoelectric absorption, as described above. The high energy scan data 1032 may be, for example, from a high energy wide field MV fan beam scan and may have relatively low known attenuation dominated by Compton scattering, a different physical mechanism. Both projections are within one or more of the same cross sections of the same object scene. In step 1040, method 1000 utilizes or combines the low energy scan data 1030 and the high energy scan data 1032 by estimating the attenuation of kV projections in the low energy kV scan 1030 through dense structures dominated by photoelectric absorption based on the corresponding high energy MV scan data 1032. Then, in step 1050, method 1000 reconstructs a low energy kV image using the attenuation estimate.

[0102] In some embodiments, the MV projections and the 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 of 150 keV or less.

[0103] I C

[0104] In some embodiments, the multimodal instrument can be utilized for time resolution correction (e.g., image blur correction). With reference to the multimodal instrument 10 of FIG. 2, in one embodiment, the MV projections from the MV source 20 are rapidly resolved in time (e.g., about 5 μs) and therefore in gantry angle compared to the kV projections from the kV source 30 (e.g., about 10 ms). Furthermore, the obtainable pulse rate is higher for the MV beam 22 (e.g., up to 300 Hz) than the typical pulse rate for the kV beam 32 of a kV-CBCT system (e.g., about 15 Hz). Blurring in the kV projections increases the exposure time and gantry rate, whether continuous or pulsed exposure. In one embodiment, the degree of blurring at the detector 34 can be, for example, about 10 pixels based on the geometry and kV operation. Again, this may require 2D correction or 3D modeling. For example, in model-based 3D solutions, MV projections can provide time-resolved information to improve the consistency of model-based reconstructions or to refine 2D deblurring operators.

[0105] For example, FIG. 11 is a flow chart depicting an exemplary method 1100 of combining scan data from multiple radiological modalities for time resolution correction (e.g., image blur correction for lung or cardiac imaging). Training data 1105 from known objects, models, etc. may be provided to refine the process. In some embodiments, a scan configuration (including a scan design for each modality of the multimodal system) may be determined and a scan may be performed according to method steps 810 and 820 of method 800 to generate scan data 1130, 1132. The low-energy scan data 1130 may be, for example, from a low-energy kV scan and may have a relatively low pulse rate (e.g., slow integration). For example, a typical kV integration time may be 5-20 ms. However, the pulse rate may range from 10-100 ms since the pulse rate is 1 / cycle period including the detector readout time. The high-energy scan data 1132 may be, for example, from a high-energy MV scan and may 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 for the MV system is not limited by the integration time. In one embodiment, a rate of up to 300 Hz is used with a cycle time of 3.3 ms. In 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 aid in the interpolation of the kV scan data 1130 with a better spatial image with fewer time point evaluations for image blur correction. Then, in step 1150, the method 1100 reconstructs a low energy kV image using image blur correction, for example for a motion blurred image with a fast temporal resolution.

[0106] In some embodiments, the high-energy scan is a MV fan beam CT and the low-energy scan is a kV narrow beam CT, In some embodiments, the high-energy scan is a MV fan beam CT and the low-energy scan is a kV cone beam CT. ID

[0107] In some embodiments, a multimodal instrument can be utilized for motion artifact correction. Referring to the multimodal instrument 10 of Figure 2, in one embodiment, as described above, the MV projections from the MV source 20 are resolved in time much more rapidly than the kV projections from the kV source 30.

[0108] For example, FIG. 12 is a flow chart depicting an exemplary method 1200 of combining scan data from multiple radiological modalities for motion artifact correction. Training data 1205 from known objects, models, etc. may be provided to refine the process. In some embodiments, a scan configuration (including a scan design for each modality of the multimodal system) may be determined and a scan may be performed according to method steps 810 and 820 of method 800 to generate scan data 1230, 1232. The low-energy scan data 1230 may be, for example, from a low-energy kV scan and is less rapidly time resolved (e.g., low frequency). The high-energy scan data 1232 may be, for example, from a high-energy MV scan and is more rapidly time resolved (e.g., high frequency). In 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 the more rapidly time-resolved projections to estimate motion for use in motion correction of 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 build a correlation model between the high-frequency MV scan data 1232 and the combined image data. The high-frequency MV scan data 1232 is then used to interpolate the high-frequency motion contained in the low-frequency kV projection data 1230 based on the correlation model 1240. Then, in step 1250, the method 1200 reconstructs a low-energy kV image using the motion correction. In another embodiment, step 1250 includes reconstructing a trajectory of otherwise high-frequency motion. 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 times may be different.For example, the low energy scan data 1230 (e.g., kV projections) may have a longer integration time (e.g., 5-30 ms), while the high energy scan data 1232 (e.g., MV projections) may have a shorter integration time (e.g., 0.001 ms). 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.

[0109] In various embodiments, the high-energy scan is a 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 radiation source 20 and the low-energy radiation source 30 are orthogonal. In one embodiment, the motion correction is based on motion estimation (based on 3D reconstruction) and applies motion correction as real-time adjustments to the second radiation source (e.g., orientation, collimation, and / or gating for uncontrolled motion) while simultaneously delivering therapeutic radiation using the second radiation source.

[0110] II.A.

[0111] In some embodiments, the multimodal instrument may be utilized for material separation and / or quantitative imaging. Referring to the multimodal instrument 10 of FIG. 2, in various embodiments, MV projections from the MV source 20 and kV projections from the kV source 30 may be acquired simultaneously, in an interleaved manner, or in a sequential 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 achieved by: can be obtained from MV images rather than kV images.However, kV-kV registration can be more accurate than kV / MV registration. In various embodiments, these differences can be used to decompose projections and voxels into a linear combination of two component materials (e.g., "soft tissue" and "bone"). By varying the contributions of the component materials, one material can be suppressed while the other is enhanced, improving image quality.

[0112] For example, FIG. 13 is a flow chart depicting an exemplary method 1300 of combining scan data from multiple radiological diagnostic modalities 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 diagnostic modality of the multimodal system) may be determined and a scan may be 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, if 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. In step 1340, the method 1300 modifies at least one component material contribution from at least one of the scan data 1330, 1332. Next, in step 1350, the method 1300 reconstructs an image using the modified contribution of the at least one component material.

[0113] In one embodiment, a quantitative image of electron density is provided by modifying the contribution of at least one component material from at least one of the scan data 1330, 1332. In some embodiments, the low energy scan data 1330 includes projection data associated with at least two spectrally separated keV energies. II.B.

[0114] In some embodiments, a multimodal instrument can be utilized for patient setup. With reference to the multimodal instrument 10 of FIG. 2, in one embodiment, 2D dual energy images (e.g., from high energy source 20 and low energy source 30) can be used in a 2D image registration workflow, switching off bone or soft tissue, for example. In one embodiment, the registration scan can be a low dose, two angle, two energy scout scan with a return scan at a gantry shift of 90 degrees, such that pairs of MV and kV projections 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 acquires only non-complementary fan data from the opposing side of the gantry 12.

[0115] For example, FIG. 14 is a flow chart depicting an exemplary method 1400 of combining scan data from multiple radiological modalities for patient setup. The prior data 1405 is from known prior images, objects, models, etc. In some embodiments, a scan configuration (including scan designs for each modality of a multimodal system) may be determined and scans may be 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 and low-energy scans are concurrent, and the high-energy source 20 and the low-energy source 30 are orthogonal as part of a scout scan workflow. In 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. Next, in step 1450, the method 1400 performs a step of: Register the patient .

[0116] In some embodiments, the scout scan is bidirectional to acquire dual-energy projections from the same gantry angle, hi some embodiments, the geometrically coincident dual-energy projections are used for material separation in the registration workflow.

[0117] II.C.

[0118] In some embodiments, the multimodal device may be utilized for online adaptive IGRT as well as offline adaptive IGRT and delivery quality assurance. Referring to the multimodal device 10 of FIG. 2, in one embodiment, online 3D kVCT uses the kV subsystem (e.g., including the low energy source 30, beamformer 36, and detector 34) for online 3D motion adaptation. This embodiment also includes using the projection data of the MV treatment beam 22 to both enhance image quality in the treatment planning target volume (PTV) and use it as a suppression in quantitative electron density images. Here, the MV exit detector 24 data is utilized in dual energy iterative reconstruction by forward projecting the MLC apertures in the MVCT geometry and enforcing projection data consistency. For example, there may be 51 MLC apertures per rotation and the high energy MV source 20 may be pulsed at 300 Hz. This results in a large number of detector counts with image information focused on the treatment structure. Using this data, a low noise quantitative image of the treatment region can be obtained. The low-noise representation allows deformable PTV tracking in addition to rigid body motion tracking so that the treatment plan can be adapted online to the PTV shape and position.

[0119] For example, FIG. 15 is a flow chart depicting an exemplary method 1500 of combining scan data from multiple radiological modalities for online adaptive IGRT. The prior data 1505 may be from known prior images, treatment plans, objects, models, etc. In some embodiments, a scan configuration (including a scan design for each modality of a multimodal 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. In step 1540, the method 1500 utilizes or combines the low-energy scan data 1530 and the high-energy scan data 1532 to complement and / or suppress the other scan data 1530, 1532. Then, in step 1550, the method 1500 adapts a treatment plan based on the complemented and / or suppressed other scan data.

[0120] In some embodiments, fluence field modulation imaging involves complementing missing MV view information with orthogonal kV projections. In some embodiments involving online 3D kV imaging, the MV treatment projections are used as suppression in quantitative electron density images. 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.

[0121] In some embodiments, the methods described above can be performed simultaneously or in an interleaved manner based on a preferred workflow, for example, a multi-modal scan can be performed and the resulting scan data can be utilized for two or more of the various features and advantages described above.

[0122] When using the above apparatus and methods in the projection domain, scatter correction can be applied to each projection viewpoint when each projection viewpoint is a planar image. Various embodiments can utilize different scan geometries, detector positioning (including offset detectors), and / or beamformer window shapes.

[0123] As noted above, aspects of the disclosed techniques are intended for use in conjunction with or as part of radiation therapy devices and IGRT, and may be utilized in methods utilizing multi-modal radiation sources, including integrated low-energy (e.g., kV) and high-energy (e.g., MV) sources. According to one embodiment, the image acquisition methodology may include or otherwise utilize helical source trajectory (e.g., continuous source rotation about a central axis accompanied by longitudinal translation of a patient support through a gantry bore) accompanied by high speed slip ring rotation, or full-circle scanning, for example, to provide kV CT imaging in a radiation therapy delivery platform.

[0124] It will be appreciated that in some embodiments, any potential scan time increase associated with multiple beam rotations to complete a volumetric image may be mitigated or otherwise offset by a high kV frame rate, high gantry rate, and / or sparse data reconstruction approach. It will be further appreciated that providing a selectively controllable collimator / beamformer as described above allows the system to allow the user to trade off or otherwise vary image acquisition time against image quality depending on the particular application and / or medical need. It will also be appreciated that the radiation therapy delivery device can be controlled to provide half-rotation or single-rotation cone beam CT scans (with the potential for reduced image quality due to scattering) with fast image acquisition times (e.g., for motion tracking), and full-circle or continuous helical acquisitions with narrow / slit fan beams with longer acquisition times but increased image quality due to reduced scattering. One or more optimization processes are also applicable to all of the above embodiments to determine scan design, determine beam positioning, determine readout range, evaluate scatter, etc.

[0125] FIG. 16 is a flow chart depicting an exemplary method 1600 of IGRT using a radiation therapy device (e.g., including the multimodal device 10). The prior data 1605 can include patient images (e.g., prior images, which may be pre-acquired planning images, including the prior CT images described above), treatment plans, phantom information, models, a priori information, etc. In some embodiments, the prior data 1605 is created by a similar radiation therapy device, but at an earlier time. In step 1610, imaging of the patient is performed using a radiation source (e.g., kV radiation from source 30 and / or MV radiation from source 20 of the multimodal device 10). In various embodiments, imaging includes a helical or circumferential scan with fan beam or cone beam geometry. Step 1610 generates one or more images or imaging / scan data 1615 of high quality (HQ) using the techniques described above. 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 image quality may be adjusted to optimize or trade off image quality / resolution versus image acquisition time. Imaging step 1610 also includes image processing 1620 to generate a patient image based on imaging / scan data 1615 (e.g., according to the methods described above). Image processing step 1620 is shown as part of imaging step 1610. In some embodiments, image processing step 1620 is a separate step, including where image processing is performed by a separate device.

[0126] Next, in step 1630, one or more image-based pre-delivery steps described below are performed based at least in part on the imaging / scan data 1615 from step 1610. As described in more detail below, step 1630 may include determining various parameters related to the treatment procedure and (subsequent) imaging planning. In some embodiments, the image-based pre-delivery step (1630) may require more imaging (1610) before treatment delivery (1640). Step 1630 may include adapting the treatment plan based on the imaging data 1615 as part of an adaptive radiation treatment routine. In some embodiments, the image-based pre-delivery step 1630 may include real-time treatment planning. Embodiments may also include simultaneous, overlapping and / or alternating activation of imaging and therapeutic radiation sources, as described above. Real-time treatment planning may involve any or all of these types of imaging and therapeutic radiation activation techniques (simultaneous, overlapping and / or alternating).

[0127] Next, in step 1640, delivery of the therapeutic treatment is performed using a source of high energy radiation (e.g., MV radiation from the therapeutic radiation source 20). Step 1640 delivers a therapeutic dose 1645 to the patient according to the treatment plan. In some embodiments, the IGRT method 1600 may include returning to step 1610 for additional imaging at various intervals (e.g., between fractions), followed by image-based pre-delivery steps (1630) and / or treatment delivery (1640) as needed. In this manner, high quality imaging data 1615 may be generated and utilized during IGRT using an adaptive therapy capable device 10. As described above, steps 1610, 1630 and / or 1640 may be performed simultaneously, overlapping, and / or alternating.

[0128] As discussed above, IGRT may include at least two general goals: (i) to deliver a highly conformal dose distribution to the target volume, and (ii) to deliver the treatment beam with high precision throughout the entire treatment. A third goal may be to achieve the two general goals in the least amount of time per portion possible. Accurate delivery of the treatment beam requires the ability to identify and / or track the position of the target volume using high quality images. The ability to increase delivery rate requires the ability to move the radiation source accurately, precisely, and rapidly according to the treatment plan.

[0129] FIG. 17 is a block diagram 1700 depicting an exemplary image-based pre-delivery step / option that may be related to step 1630 above. It will be understood that the multimodal device 10 (e.g., as part of a radiation therapy device) described above can generate low-energy and high-energy images that can be used in a variety of ways, including for the purpose of the image-based pre-delivery step (1630), without departing from the scope of the present invention. For example, images 1615 generated by the radiation therapy device can be used to set up or align the patient prior to treatment (1710). Aligning the patient can include correlating or registering the current imaging data 1615 with imaging data related to the plan, including earlier pre-treatment scans and / or the treatment plan. Aligning the patient can 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 delivery system. If necessary, the patient can be adjusted accordingly. In some embodiments, patient alignment imaging may be intentionally lower quality to minimize dose but provide proper alignment information. An exemplary patient alignment process is described below.

[0130] The images generated by the multimodal device 10 may also be used for treatment planning or treatment re-planning (1720). In various embodiments, step 1720 may include confirming the treatment plan, modifying the treatment plan, creating a new treatment plan, and / or selecting a treatment plan from a set of treatment plans (sometimes referred to as a "daily plan"). For example, the imaging data 1615 indicates that the target volume or ROI is similar to that of the developed treatment plan. The treatment plan may then be confirmed. However, if the target volume or ROI is not the same, re-planning of the treatment procedure may be required. In the case of re-planning, since the imaging data 1615 (generated by the multimodal device 10 in step 1610) is of high quality, the imaging data 1615 may be used for treatment planning or treatment re-planning (e.g., creating a new or revised treatment plan). In this way, pre-treatment CT imaging with a different device is not required. In some embodiments, confirmation and / or treatment re-planning may be an ongoing procedure before and / or after various treatments.

[0131] According to another exemplary use case, images generated by the multimodal device 10 can be used to calculate an imaging dose (1730), which may be used to determine an overall dose to the patient on-the-fly and / or for subsequent imaging planning. The quality of the subsequent imaging may also be determined as part of the treatment planning, e.g., to balance quality and dose. According to another exemplary use case, images generated by the multimodal device 10 can be used to calculate a treatment dose (1740), which may be used to determine an overall dose to the patient on-the-fly and / or may be included as part of the treatment planning or treatment re-planning.

[0132] According to other exemplary use cases, images generated by the multimodal device 10 may be used in connection with planning or adjusting other imaging (1750) and / or other treatment (1760) parameters or plans, such as included as part of creating an adaptive treatment and / or treatment plan. According to another exemplary use case, images generated by the multimodal device 10 may be used in connection with adaptive treatment monitoring (1770), which may include monitoring and adapting, including replanning, treatment delivery as needed.

[0133] The image-based pre-delivery steps (1630) are not mutually exclusive. For example, in various embodiments, calculated treatment dose (1740) may be a stand-alone step and / or may be part of adaptive treatment monitoring (1770) and / or treatment planning (1720). In various embodiments, the image-based pre-delivery steps (1630) may be performed automatically and / or manually with human intervention.

[0134] FIG. 18 is a block diagram 1800 representing exemplary data sources that may be utilized during imaging (1610) and / or during the subsequent image-based pre-delivery step (1630). Detector data 1810 represents data received by the radiation detector 24, 34. Projection data 1820 is data generated by radiation incident in a narrowed beam region, referred to above as the active region. Penumbra data 1830 is data generated by radiation incident in the penumbra region. Scatter data 1840 is data generated by radiation incident in a peripheral region outside the penumbra region and / or the determined scatter as described above. In another embodiment, the scatter data 1840 can be used to determine residual effects of scatter from the therapeutic radiation source 20 (e.g., MV) when the two sources 20, 30 are operated simultaneously or in an interleaved manner.

[0135] In this manner, the penumbra data 1830 and / or the scatter data 1840 may be utilized to improve the quality of the image generated by the imaging step 1610. In some embodiments, the penumbra data 1830 and / or the scatter data 1840 may be combined with the projection data 1820 and / or analyzed in terms of the applicable imaging settings 1850, treatment settings 1860 (e.g., in the case of simultaneous imaging and / or treatment radiation), and any other data 1870 related to the multimodal device 10 at the time of data collection at the detectors 24, 34. In other embodiments, the data may be used for the treatment planning step 1630.

[0136] 19 and 20 depict exemplary embodiments of imaging 1610, image-based pre-delivery steps 1630, and therapy delivery 1640 use cases, including examples of various forward and feedback sequences associated with on-board imaging using the multimodal device 10 during IGRT, including use of the methods described above.

[0137] FIG. 19 is a flow chart depicting an exemplary method 1900 including patient setup or alignment with a radiation therapy device (e.g., including multimodal device 10). Prior data 1905 can include images of the patient (e.g., prior images including prior CT images as described above, which may be pre-acquired planning images). In some embodiments, prior data 1905 is created with a similar radiation therapy device, but at an earlier time. In step 1910, an initial or preliminary alignment of the patient can be performed. Next, in step 1920, an on-board imaging scan is performed using a low-energy radiation source and / or a high-energy radiation source (e.g., kV radiation from source 30 and / or MV radiation from source 20) of multimodal device 10, including, for example, as described in step 1610 above. In various embodiments, on-board imaging includes a helical scan or a full-circle scan with a fan-beam geometry or a cone-beam geometry. Step 1920 generates online imaging / scan data 1930 using the techniques described above. The imaging step 1920 may also include image processing to generate patient images based on the imaging / scan data 1930 (eg, according to the methods described above), including, for example, those described in block 1620 above.

[0138] Next, step 1940 determines whether alignment correction is needed 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 needed, method 1900 proceeds to step 1950 for alignment correction based at least in part on the online scan data 1930. After alignment correction, the method can then return to step 1920 for additional imaging as a confirmation or further refinement loop. If alignment correction or adjustment is not needed from step 1940, method 1900 proceeds to step 1960 for treatment delivery. After treatment, method 1900 can then return to step 1920 for additional imaging as a confirmation or further refinement loop.

[0139] FIG. 20 is a flow chart depicting an exemplary method 2000 of adaptive IGRT using a radiation therapy device (e.g., including multimodal device 10). Pre-treatment planning data 2005 can include treatment plans and patient images (e.g., pre-images, which may be pre-acquired planning images, including pre-CT images as described above), phantom information, models, a priori information, and the like. In some embodiments, the pre-data 2005 is created by a similar radiation therapy device, but at an earlier time. In step 2010, for example, an initial or preliminary treatment plan can be adopted based on the pre-treatment plan and any additional information. Next, in step 2020, an on-board imaging scan is performed using a low-energy radiation source and / or a high-energy radiation source (e.g., kV radiation from source 30 and / or MV radiation from source 20) of the multimodal device 10, including, for example, as described in step 1610 above. In various embodiments, the on-board imaging includes a helical scan or a full-circle scan with a fan-beam geometry or a cone-beam geometry. Step 2020 uses the techniques described above to generate online imaging / scan data 2030. Imaging step 2020 may also include image processing to generate patient images based on the imaging / scan data 2030 (e.g., according to the methods described above), including, for example, those described in block 1620 above.

[0140] Step 2040 then determines whether the treatment plan needs to be re-planned or adapted based at least in part on the online scan data 2030, including, for example, as described in block 1720 above. If the treatment plan does not need to be adapted or re-planned, method 2000 proceeds to step 2050 for treatment delivery. If the treatment plan needs to be adapted or re-planned, method 2000 proceeds to step 2060 of adapting the treatment plan based at least in part on the online scan data 2030. After adapting the treatment plan, the method can proceed to step 2050 for treatment delivery. After treatment, method 2000 can then return to step 2020 for additional imaging as a confirmation or further refinement loop.

[0141] 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 on-board imaging scan may be performed and utilized as both the 1920 and 2020 scans, and the same data may be used to simultaneously verify treatment and sequential registration. In other embodiments, two or more of the image-based pre-delivery steps 1630 may be performed simultaneously or in an interleaved manner based on a preferred workflow, including when the same imaging data 1615 and / or image processing 1620 are utilized for more than one of the image-based pre-delivery steps 1630.

[0142] Although the disclosed methodology has been shown and described with respect to certain aspects, embodiments or embodiments, it will be apparent that equivalent changes and modifications will occur to those skilled in the art upon reading and understanding this specification and the accompanying drawings. In particular, with respect to the various functions performed by the above-mentioned elements (components, assemblies, devices, members, compositions, etc.), the terms used to describe such elements (including references to "means") are intended to correspond to any element that performs the specified function of the described element (i.e., functionally equivalent), even if it is not structurally equivalent to the disclosed structure that performs that function in the exemplary aspects, embodiments or embodiments of the disclosed technology shown herein, unless otherwise indicated. Moreover, although certain features of the disclosed methodology may be described above with respect to only one or more of some illustrated aspects or embodiments, such features can be combined with one or more other features of other embodiments, as may be desired and advantageous for any given or particular application.

[0143] Although the embodiments described herein relate to the above systems and methods, these embodiments are intended to be exemplary and are not intended to limit the applicability of these embodiments to only the descriptions set forth herein. Although the present invention has been illustrated by the description of its embodiments, and the embodiments have been described in some detail, it is not the intention of the applicant to limit, or in any way limit, the scope of the appended claims to such details. Further advantages and modifications will be readily apparent to those skilled in the art. Thus, the broader aspects of the present invention are not limited to the specific details, exemplary apparatus and methods, and illustrative examples shown and described. Thus, departures may be made from such details without departing from the spirit or scope of the applicant's general inventive concept.

Claims

1. 1. A multimodal imaging device comprising: a rotatable gantry system positioned at least partially about a patient support; a first radiation source coupled to the rotatable gantry system and configured for imaging radiation; and a second radiation source coupled to the rotatable gantry system, configured for at least one of imaging radiation or therapeutic radiation, and having a higher energy level than the first radiation source; 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; first measured projection data generated from the first radiation source includes greater attenuation of radiation than second measured projection data generated from the second radiation source; an attenuation estimate of radiation associated with the first measured projection data is generated by estimating an attenuation of the first measured projection data through a high density structure that is affected by photoelectric absorption based on the second measured projection data, and reconstructing an image from the first measured projection data based thereon; A multimodal imaging device that uses the first measured projection data and material property measurements derived from the second measured projection data to decompose a plurality of component materials into a linear combination and reconstruct an image.

2. 10. The instrument of claim 1, wherein the first radiation source comprises a kiloelectron volt peak photon energy (keV) up to 150 keV and the second radiation source comprises a megaelectron volt peak photon energy (MeV) of 1 MeV or greater.

3. 10. The apparatus of claim 1, wherein the second radiation source comprises a peak energy of 3 MeV and an average energy of about 1 MeV.

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

5. The apparatus of claim 1 , wherein the second measured projection data comprises sparse projection data.

6. The apparatus of claim 1 , wherein the first measured projection data or the second measured projection data is measured during a helical scan.

7. The apparatus of claim 1 , wherein the first measured projection data or the second measured projection data is measured during a full circumference scan.

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

9. The apparatus of claim 1 , wherein at least one of the first radiation source or the second radiation source is configured to generate a fan beam shape.

10. The apparatus of claim 1 , wherein at least one of the first radiation source or the second radiation source is configured to generate a cone beam geometry.

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

12. 2. The apparatus of claim 1, wherein the first measured projection data includes more scattering than the second measured projection data, and a first scattering estimate associated with the first measured projection data is based on the second measured projection data.

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

14. 2. The apparatus of claim 1, wherein the first measured projection data is measured at a first frequency and the second measured projection data is measured at a second frequency, the first frequency being less than the second frequency, and a motion assessment of the first measured projection data is based on the second measured projection data.

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

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

17. 2. The apparatus of claim 1, wherein the first measured projection data is integrated over a first time period and the second measured projection data is integrated over a second time period, the first time period being greater than the second time period, and wherein reconstruction of the first measured projection data is based on the second measured projection data.

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

19. 1. A method for correcting image artifacts using a multimodal 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 at least one of imaging radiation or therapeutic radiation, the second radiation source having a higher energy level than the first radiation source, the first measured projection data including more radiation attenuation than the second measured projection data; determining an attenuation estimate of a first radiation associated with the first measured projection data based on the second measured projection data; an attenuation estimate of radiation associated with the first measured projection data is generated by estimating an attenuation of the first measured projection data through a high density structure that is affected by photoelectric absorption based on the second measured projection data, and reconstructing an image from the first measured projection data based thereon; A method of reconstructing an image by decomposing a plurality of component materials into a linear combination using the first measured projection data and measurements of material properties derived from the second measured projection data.

20. 20. The method of 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. 20. The method of claim 19, further comprising reconstructing an image based on the first radiation attenuation estimate and the first measured projection data.

22. The method of claim 21 , further comprising: during a patient registration workflow, performing patient registration based on the reconstructed image.

23. 22. The method of claim 21, further comprising modifying a treatment plan based on the reconstructed image during an adaptive planning workflow.

24. 22. The method of claim 21, further comprising calculating a treatment dose delivered to a patient based on the reconstructed image.

25. 1. A radiation therapy delivery device comprising: a rotatable gantry system positioned at least partially about a patient support; a first radiation source coupled to the rotatable gantry system and configured for imaging radiation; and a second radiation source coupled to the rotatable gantry system, configured for at least one of imaging radiation or therapeutic radiation, and having a higher energy level than the first radiation source; 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; a first measured projection data from the first radiation source includes more radiation attenuation than a second measured projection data from the second radiation source, and a first radiation attenuation estimate associated with the first measured projection data is based on the second measured projection data; The radiation therapy delivery device further comprises:

1. A data processing system comprising: configured to receive measured projection data from the first radiation source and the second radiation source, wherein a first measured projection data from the first radiation source includes more attenuation of radiation than a second measured projection data from the second radiation source; an attenuation estimate of radiation associated with the first measured projection data is generated by estimating an attenuation of the first measured projection data through a high density structure that is affected by photoelectric absorption based on the second measured projection data, and reconstructing an image from the first measured projection data based thereon; and a data processing system that uses the first measured projection data and material property measurements derived from the second measured projection data to decompose a plurality of component materials into a linear combination and reconstruct an image.

Images