Calibration phantom holder system and method

Abstract

To provide a calibration phantom holder which reduces the number of components required for calibration and an installation area, and also reduces the number of user operations of an engineer who performs calibration.SOLUTION: A calibration phantom holder for an imaging system is provided. In an example, the calibration phantom holder comprises a horizontal member comprising a plurality of parallel slots on a top surface of the horizontal member. Each parallel slot of the plurality of parallel slots is configured to support one or more calibration phantoms. The calibration phantom holder includes a vertical member perpendicularly coupled to the horizontal member. The vertical member is configured to couple to a support system of the imaging system.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] FIELD OF THE INVENTION Embodiments of the subject matter disclosed herein relate to phantoms, and more particularly to holders for one or more phantoms used to calibrate photon-counting CT scanners. [Background technology]

[0002] In a computed tomography (CT) imaging system, a cathode generates an electron beam and directs it toward a target in an x-ray source or tube. The electrons strike the target, producing a fan- or cone-shaped x-ray beam that is then directed toward an object (e.g., a patient). After being attenuated by the object, the x-rays strike an array of x-ray detectors, producing an image. One example of a CT system is a photon-counting CT (PCCT) system, where the x-ray detectors are photon-counting detectors and photons are counted to obtain spectral information. In a PCCT system, a calibration process is periodically performed. The calibration process can include performing a CT imaging procedure on an object, called a phantom, and generating correction factors based on the resulting phantom images. The phantom can be made of stacked slabs of material, and the composition of the layers can be changed between calibration scans. In some examples, the calibration process can include scanning multiple stacks and adding or removing slabs from the stack between calibration scans. Furthermore, the stacked slabs are placed in the path of the X-ray beam during scanning and calibration is performed. Summary of the Invention

[0003] In one embodiment, a calibration phantom holder for an imaging system is provided, the calibration phantom holder including: a horizontal member including a plurality of parallel slots on an upper surface of the horizontal member, each parallel slot of the plurality of parallel slots configured to support one or more calibration phantoms; and a vertical member vertically coupled to the horizontal member, the vertical member configured to couple to a support system of the imaging system.

[0004] These and other advantages and features of the present specification will be readily apparent from the following detailed description alone, or by reading the detailed description in conjunction with the drawings. It should be understood that the foregoing summary is provided to introduce in a simplified form selected concepts that are further described in the detailed description. The foregoing summary is not intended to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims. Moreover, the claimed subject matter is not limited to implementations that solve any shortcomings noted above or anywhere in this disclosure. [Brief explanation of the drawings]

[0005] The various aspects of the present disclosure can be further understood by reading the following detailed description and by reference to the drawings, in which: [Figure 1] 1 shows a diagram of a photon-counting computed tomography (PCT) imaging system in accordance with one or more embodiments of the present disclosure. [Figure 2] 1 shows a schematic block diagram of an exemplary PCCT imaging system in accordance with one or more embodiments of the present disclosure. [Figure 3] 1 shows a front perspective view of a first example of a calibration phantom holder according to an embodiment of the present disclosure. [Figure 4] 4 illustrates a side view of the calibration phantom holder of FIG. 3 in accordance with an embodiment of the present disclosure. [Figure 5]4 illustrates a rear perspective view of the calibration phantom holder of FIG. 3 in accordance with an embodiment of the present disclosure. [Figure 6] 4 illustrates a rear perspective view of the calibration phantom holder of FIG. 3 coupled to a cradle clamp holder according to an embodiment of the present disclosure. [Figure 7] FIG. 10 shows a side view of a second example of a calibration phantom holder with a slab of material bonded thereto, according to an embodiment of the present disclosure. [Figure 8] FIG. 10 shows a rear perspective view of a third example of a calibration phantom holder coupled to a cradle clamp holder, the calibration phantom holder including one or more rods for securing a slab in place, according to an embodiment of the present disclosure. [Figure 9] 9 is a schematic diagram of a slab coupled to a rod (such as one of the rods shown in FIG. 8) according to an embodiment of the present disclosure. [Figure 10] FIG. 1 is a perspective view of a first phantom according to an embodiment of the present disclosure. [Figure 11] FIG. 10 is a perspective view of a second phantom according to an embodiment of the present disclosure. [Figure 12] 10 is a flowchart illustrating a method for preparing a calibration phantom holder for use in calibration, according to an embodiment of the present disclosure. [Figure 13] 1 is a flowchart illustrating a method for calibrating a PCCT device using a phantom assembled in a calibration phantom holder, according to an embodiment of the present disclosure. [Figure 14] FIG. 1 is a perspective view of an exemplary calibration phantom holder positioned for a calibration process in an imaging system, according to an embodiment of the present disclosure. [Figure 15] FIG. 10 is a perspective view of an example of a detent for a calibration phantom holder, according to an embodiment of the present disclosure. [Figure 16] FIG. 10 is a perspective view of an exemplary threaded insert for a calibration phantom holder according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0006] Descriptions and embodiments of the subject matter disclosed herein relate to a phantom holder for calibration scans of an imaging system (such as a photon-counting computed tomography (PCCT) system). An imaging system (such as a PCCT system) may require periodic calibration scans (such as daily or weekly calibration scans) to offset gain drift resulting from hardware such as changes in the focal position of an x-ray tube or radiation degradation of a detector. Furthermore, a PCCT system may obtain spectral information for generating reference material differentiation (BMD) images. Calibration of a PCCT system may thereby require acquisition of calibration projection data that simulates the materials and material thicknesses of a human body. Thus, a phantom for calibrating a PCCT system may include multiple different materials (such as slabs of polyvinyl chloride (PVC) and polyethylene (PE) arranged in a stack). In some examples, multiple stacks may be scanned during the calibration process. Furthermore, slabs may be added or removed from the stack during the calibration process.

[0007] With current methods, stacks of slabs are scanned one at a time, and the stacks are manually loaded by technicians onto a holder from above or directly onto a cradle and moved into the scan path of the PCCT system. Slabs are often large and heavy, and the space available for loading and replacing stacks of slabs is limited, potentially causing injury to technicians and damage to the slabs. Therefore, with a calibration process involving as many as 40 possible slab combinations, calibrating a PCCT system can be physically demanding and time-consuming. Furthermore, current methods are prone to misalignment, which can negatively impact the calibration.

[0008] Therefore, disclosed herein is a calibration phantom holder that reduces the number of components and footprint required for calibration and also reduces the number of user operations required by a technician performing the calibration. The calibration phantom holder includes a horizontal member and a vertical member vertically coupled to the horizontal member. The horizontal member includes a plurality of parallel slots distributed on an upper surface of the horizontal member. Each of the plurality of parallel slots is configured to support one or more calibration phantoms. The vertical member is configured to couple to a support system, such that the phantom holder can be coupled to a cradle (e.g., a cradle of a patient table) of a PCCT scanner and positioned within the scan path. In this manner, the phantom holder is adapted to easily accommodate interchangeable phantoms, allowing phantoms to be attached to or detached from the phantom holder during the calibration process.

[0009] The disclosed calibration phantom holder is designed to support a modular slab phantom, allowing multiple combinations of slabs to be stacked next to each other. The horizontal member has an open-platter design configured to support multiple slabs stacked vertically one on top of another, multiple slabs arranged horizontally side by side, or both. The slots in the disclosed calibration phantom holder allow slabs to be loaded sideways rather than from above. Each of the multiple parallel slots may include a dovetail shape and, in some examples, one or more detents. The calibration phantom supported by the holder includes slotted slabs that can be slid into corresponding slots in the phantom holder from either side of the horizontal member, thereby reducing the user's effort to load the slabs. Another advantage of side-loading is improved maneuverability in the typically space-constrained environment of a CT scanner. Additionally, the vertical member may include one or more openings configured to function as handles. Therefore, the calibration phantom holder can be easily transported from storage to the CT scanner.

[0010] To simplify user operation, the entire holder holding multiple stacks of slabs can be adjusted and placed into the bore of the PCCT system for scanning. The stacks can be scanned in an order that reduces the effort required to remove or add slabs from the top of the stack. Some slab holder embodiments allow for slab removal from the bottom of the stack as well as from the top. In some examples, a calibration phantom, such as a slotted slab, can include an upper slot and a lower tab. The lower tab can be configured to slide into a corresponding one of the slots, and the upper slot can be configured to support a second calibration phantom. Thus, slotted slabs of various densities, dimensions, materials, etc. can be stacked in various combinations and easily added to or removed from the holder.

[0011] Another advantage of the slotted design is reduced misalignment, since the slots act as guides to ensure the calibration phantom's placement is reproducible. Furthermore, in some embodiments, the slotted slabs include openings configured to accept rods that can be inserted vertically into the stack, and in some embodiments, the rods can be coupled to horizontal members. The rods and rod openings can serve as additional guides to ensure the calibration phantom's placement is reproducible. Additionally or alternatively, detents can be used to hold the calibration phantom in place. Furthermore, the calibration phantom holder can be constructed of one substrate (e.g., a non-metallic material) of multiple substrates used in the calibration process. In this way, the calibration phantom holder itself can serve as a substrate for all slab combinations stacked in the calibration phantom holder, allowing the calibration phantom holder to be scanned. By being able to scan multiple slab combinations at once and reducing the number of slabs required for calibration, the disclosed calibration phantom holder and systems and methods for the disclosed calibration holder improve the efficiency of the calibration process.

[0012] The calibration phantom holder can be used with a PCCT system (such as the PCCT system described with respect to FIGS. 1 and 2). FIGS. 3-6 show an exemplary calibration phantom holder capable of holding one or more slabs to form a phantom. As described above, the holder can have a flat base and a vertical back panel perpendicularly coupled to the flat base. FIG. 7 shows an exemplary slab fitted to the flat base of a second embodiment of the calibration phantom holder. FIGS. 8-9 show an example of a slab with an opening, through which the slab can be secured to the holder by a rod inserted into the opening. The slabs can be stacked in a specific order based on the clinical purpose of the PCCT scanner, and slabs can be added to or removed from the stack between scans during the calibration process. Example slab configurations can be seen in FIGS. 10-11. The vertical back panel of the holder can include a mounting for a support system (such as a cradle clamp holder) that allows the phantom holder to be coupled to the cradle of the PCCT system. An example of a calibration phantom holder coupled to a cradle clamp holder is shown in Figure 6. Figures 12-13 illustrate a method of using an example of the disclosed phantom holder to calibrate a PCCT device. An example of the disclosed phantom holder positioned to perform a calibration scan of an exemplary PCCT device is shown in Figure 14. Example detents can be seen in Figure 15.

[0013] FIG. 1 illustrates an exemplary computed tomography system 100 configured for CT imaging. In particular, imaging system 100 is configured to image a subject 112 (such as a patient, an inanimate object, one or more manufactured parts, and / or a foreign object present in a body, such as a dental implant, a stent, and / or a contrast agent). In one embodiment, imaging system 100 includes a gantry 102, which may further include at least one X-ray source 104 configured to emit a beam of X-ray radiation 106 (see FIG. 2 ) for use in imaging a subject residing on a table 114 and / or supported to protrude from the end of table 114. Specifically, X-ray source 104 is configured to emit the beam of X-ray radiation 106 toward a detector array 108 located on the opposite side of gantry 102. While FIG. 1 illustrates a single X-ray source 104, in certain embodiments, multiple X-ray sources 104 may be used. An X-ray source and multiple detectors can be used to emit multiple beams of X-ray radiation and acquire projection data at different energy levels corresponding to the patient. In some embodiments, the X-ray source 104 can achieve dual-energy gemstone spectral imaging (GSI) through rapid kilovolt peak voltage (kVp) switching. In some embodiments, the X-ray detectors used are photon-counting detectors capable of distinguishing between X-ray photons of different energies. In other embodiments, two sets of X-ray sources and detectors are used, one set at low kVp and the other at high kVp, to generate dual-energy projections. Thus, it should be understood that the methods described herein can be implemented with single-energy and dual-energy acquisition techniques.

[0014] In certain embodiments, the imaging system 100 further includes an image processor unit 110 configured to reconstruct an image of the target volume of the subject using an iterative image reconstruction method or an analytical image reconstruction method. For example, the image processor unit 110 may reconstruct an image of the target volume of the patient using an analytical image reconstruction method (such as filtered back projection (FBP)). In another example, the image processor unit 110 may reconstruct an image of the target volume of the subject using an iterative image reconstruction method (such as advanced statistical iterative reconstruction (ASIR), conjugate gradient (CG), maximum likelihood expectation maximization (MLEM), model-based iterative reconstruction (MBIR), etc.). As described further herein, in some embodiments, the image processor unit 110 may use an analytical image reconstruction method (such as FBP) in addition to an iterative image reconstruction method.

[0015] In some CT imaging system configurations, an x-ray source emits a cone-shaped beam of x-ray radiation, which is collimated to lie within the XYZ plane of a Cartesian coordinate system, commonly referred to as the "imaging plane." The x-ray radiation beam passes through the object being imaged (such as a patient or subject). After being attenuated by the object, the x-ray radiation beam impinges on an array of detector elements. The intensity of the attenuated x-ray radiation beam received by the detector array depends on the attenuation of the radiation beam by the object. Each detector element in the array produces a separate electrical signal that is a measurement of the attenuation of the x-ray beam at the detector location. The attenuation measurements from all detector elements are acquired separately to produce a transmission profile.

[0016] In some CT systems, the x-ray source and detector array are rotated by a gantry around the object being imaged within the imaging plane, constantly changing the angle at which the radiation beam intersects the object. A group of x-ray attenuation measurements, e.g., projection data, obtained from the detector array for one gantry angle is called a “view.” A “scan” of an object involves a set of views at different gantry angles, or view angles, obtained during one rotation of the x-ray source and detector. Because the benefits of the methods described herein may be obtained with medical imaging modalities other than CT, the term “view” is not limited to its use herein in reference to projection data from one gantry angle. The term “view” is used to refer to a single data acquisition when multiple data are acquired from different angles, whether by CT, positron emission tomography (PET), single photon emission CT (SPECT), and / or other modalities (including future modalities and, in fused embodiments, a combination of these modalities).

[0017] The projection data is processed to reconstruct an image corresponding to a two-dimensional slice taken through the object, or in some cases where the projection data includes multiple views or scans, to reconstruct a three-dimensional rendering of the object. One method for reconstructing an image from a set of projection data is referred to in the art as filtered backprojection. Transmission and emission tomography reconstruction techniques also include statistical iterative methods (such as maximum likelihood expectation maximization (MLEM) and ordered subset expectation reconstruction) and iterative reconstruction methods. This process converts attenuation measurements from the scan into integers called "CT numbers" or "Hounsfield units." This integer is used to control the brightness of the corresponding pixel on a display device.

[0018] To reduce overall scan time, a "helical" scan can be performed by moving the patient while acquiring data for a given number of slices. In such systems, a cone-beam helical scan generates a spiral. The spiral traced by the cone beam generates projection data from which an image of each given slice can be reconstructed.

[0019] As used herein, the phrase "reconstructing an image" is not intended to exclude embodiments of the invention in which data representing an image is generated but no viewable image is generated. Accordingly, as used herein, the term "image" broadly refers to both a viewable image and data representing a viewable image. However, in many embodiments, at least one viewable image is generated (or configured to be generated).

[0020] The table 114 includes a cradle 120 supported by a base 122. In some embodiments, the base 122 may include wheels configured to move the table 114 into and out of a bore 124 of the gantry 102. The cradle 120 includes a support system 116 configured to support an object to be imaged (e.g., a phantom and / or a patient body). The support system 116 is coupled to a first end 118 of the cradle 120, such that the support system 116 and the object to be imaged supported by the support system 116 can be loaded into the gantry 102 of the imaging system 100. As disclosed herein, the support system 116 can be configured to support a calibration phantom holder that is loaded into the bore 124 of the gantry 102 during a calibration process. An exemplary support system 116 may include a cradle clamp holder configured to couple to the cradle 120 of the imaging system 100 using a clamp attached to a side of the cradle 120. The cradle clamp holder is configured to support (e.g., protrude from first end 118 of cradle 120) a subject to be imaged (such as the disclosed calibration phantom holder supporting multiple slabs) that may be heavier than would be supported by a conventional support system 116. Further details of an example cradle clamp holder are described with respect to Figures 6 and 8.

[0021] FIG. 2 illustrates an exemplary imaging system 200 similar to the imaging system 100 of FIG. 1. The imaging system 200 is configured to image an object 204 in accordance with aspects of the present disclosure. In one embodiment, the imaging system 200 includes a detector array 108 (see FIG. 1). The detector array 108 further includes a plurality of detector elements 202 that sense an x-ray radiation beam 106 (see FIG. 2) passing through the object 204 (e.g., a patient) and acquire corresponding projection data. Thus, in one embodiment, the detector array 108 is fabricated in a multi-slice configuration that includes multiple rows of cells or detector elements 202. In such a configuration, one or more additional rows of detector elements 202 are arranged in a parallel configuration to acquire projection data.

[0022] In certain embodiments, imaging system 200 is configured to move through different angular positions around object 204 to acquire desired projection data. Thus, gantry 102 and the components mounted on gantry 102 may be configured to rotate about center of rotation 206 to acquire projection data at different energy levels, for example. Alternatively, in embodiments where the projection angle relative to object 204 changes as a function of time, the mounted components may be configured to move along a general curve rather than a circular arc.

[0023] As the x-ray source 104 and detector array 108 rotate, the detector array 108 collects data of the attenuated x-ray beam. The data collected by the detector array 108 is pre-processed and calibrated to condition the data to represent the line integrals of the attenuation coefficients of the scanned object 204. The processed data are commonly referred to as projections.

[0024] In some embodiments, the individual detectors or detector elements 202 of the detector array 108 may include photon-counting detectors that record the interactions of individual photons in one or more energy bins. It should be noted that the methods described herein may also be implemented with energy-integrating detectors.

[0025] The acquired set of projection data can be used for reference material decomposition (BMD). During BMD, the measured projections are converted into a set of material density projections. The material density projections can be reconstructed to form a set of material density maps (such as maps of bone, soft tissue, and / or contrast agent) or material density images for each reference material. The density maps or density images can be correlated in order to form a volumetric rendering of the reference materials (e.g., bone, soft tissue, and / or contrast agent) within the imaged volume.

[0026] Once reconstructed, the reference material images produced by the imaging system 200 reveal internal features of the subject 204, represented by the densities of the two reference materials. The density images may be displayed to show these features. In traditional methods of diagnosing medical conditions (such as disease states), and more generally, medical events, a radiologist or physician examines hard copies or displayed density images to identify features of interest. Such features include lesions, the size and shape of particular anatomical structures or organs, and other features discernible from the images based on the skill and knowledge of the individual medical professional.

[0027] In one embodiment, imaging system 200 includes a control mechanism 208 that controls the movement of components, such as the rotation of gantry 102 and the operation of x-ray source 104. In certain embodiments, control mechanism 208 further includes an x-ray controller 210 configured to provide power and timing signals to x-ray source 104. Control mechanism 208 further includes a gantry motor controller 212 configured to control the rotational speed and / or rotational position of gantry 102 based on imaging requirements.

[0028] In certain embodiments, the control mechanism 208 further includes a data acquisition system (DAS) 214 that samples analog data received from the detector elements 202 and converts the analog data to a digital signal for subsequent processing. The DAS 214 may be further configured to selectively aggregate analog data from a subset of the detector elements 202 into a so-called macro-detector, as described further herein. The data sampled and digitized by the DAS 214 is transmitted to a computer or computing device 216. In one example, the computing device 216 stores the data in a storage device or mass storage device 218. The storage device 218 may include, for example, a hard disk drive, a floppy disk drive, a compact disk read / write (CD-R / W) drive, a digital versatile disk (DVD) drive, a flash drive, and / or a solid-state storage drive.

[0029] Additionally, the computing device 216 provides commands and parameters to one or more of the DAS 214, the X-ray controller 210, and the gantry motor controller 212 to control system operation (e.g., data acquisition and / or data processing). In certain embodiments, the computing device 216 controls system operation based on operator input. The computing device 216 receives operator input, including, for example, commands and / or scan parameters, through an operator console 220 operably coupled to the computing device 216. The operator console 220 may include a keyboard (not shown) or a touch screen to enable an operator to specify commands and / or scan parameters.

[0030] 2 shows one operator console 220, multiple operator consoles may be coupled to imaging system 200, for example, to input or output system parameters, request examinations, plot data, and / or display images. Additionally, in certain embodiments, imaging system 200 may be coupled to multiple displays, printers, workstations, and / or similar devices located locally, remotely, or at entirely different locations, e.g., within a facility or hospital, through one or more configurable wired and / or wireless networks (e.g., the Internet and / or virtual private networks, wireless telephone networks, wireless local area networks, wired local area networks, wireless wide area networks, wired wide area networks, etc.).

[0031] In one embodiment, for example, imaging system 200 includes or is coupled to a Picture Archiving and Communication System (PACS) 224. In an exemplary implementation, PACS 224 is further coupled to remote systems (such as a radiology information system, a hospital information system, and / or an internal or external network (not shown)) to enable operators at different locations to provide commands and parameters and / or access image data.

[0032] The computing device 216 may use operator-supplied and / or system-defined commands and parameters to operate a table motor controller 226, which in turn may control the table 114. The table 114 may be a motorized table. Specifically, the table motor controller 226 may move the table 114 so that the subject 204 is properly positioned within the gantry 102 to acquire projection data corresponding to a target volume of the subject 204.

[0033] As described above, DAS 214 samples and digitizes the projection data acquired by detector elements 202. Image reconstructor 230 then performs high-speed reconstruction using the sampled and digitized x-ray data. While image reconstructor 230 is shown as a separate entity in FIG. 2 , in certain embodiments, image reconstructor 230 may form part of computing device 216. Alternatively, image reconstructor 230 may not be present in imaging system 200, and computing device 216 may perform one or more functions of image reconstructor 230. Furthermore, image reconstructor 230 may be located locally or remotely and operably connected to imaging system 200 using a wired or wireless network. Notably, in one exemplary embodiment, the computing resources of a “cloud” network cluster may be used for image reconstructor 230.

[0034] In one embodiment, image reconstructor 230 stores the reconstructed image in storage device 218. Alternatively, image reconstructor 230 may transmit the reconstructed image to computing device 216 for generating patient information useful for diagnosis and evaluation. In certain embodiments, computing device 216 may transmit the reconstructed image and / or patient information to a display or presentation device 232 communicatively coupled to computing device 216 and / or image reconstructor 230. In some embodiments, the reconstructed image is transmitted from computing device 216 or image reconstructor 230 to storage device 218 for short-term or long-term storage.

[0035] Although a CT system is described as an example, it should be understood that the present technique can also be used with other imaging modalities, including X-ray imaging systems, magnetic resonance imaging (MRI) systems, nuclear medicine imaging systems, positron emission tomography (PET) imaging systems, single photon emission computed tomography (SPECT) imaging systems, ultrasound imaging systems, and combinations thereof (e.g., multi-modality imaging systems such as PET / CT imaging systems or PET / MR imaging systems). This description of the CT imaging modality is provided merely as an example of suitable imaging modalities.

[0036] FIGS. 3-5 show multiple views of calibration phantom holder 300 and will be collectively described. Some elements of calibration phantom holder 300 may be illustrated in one or more of FIGS. 3-5, may be at least partially obstructed from the viewer's field of view in one or more of FIGS. 3-5, or may be omitted from the viewer's field of view in one or more of FIGS. 3-5. Each of FIGS. 3-5 includes a Cartesian coordinate system 301. In one example, the z-axis of coordinate system 301 may be a vertical axis (e.g., an axis parallel to the axis of gravity), the y-axis of coordinate system 301 may be a longitudinal axis (e.g., a horizontal axis), and / or the x-axis of coordinate system 301 may be a horizontal axis. However, in other examples, these axes may be oriented in other directions. When referring to directions, the directions of the arrows on the x-, y-, and z-axes represent positive, and the opposite directions of the arrows on the x-, y-, and z-axes represent negative. Filled circles represent arrows and axes pointing toward (or in a positive direction relative to) the viewpoint. Unfilled circles can represent arrows and axes pointing away from (or in a negative direction relative to) the viewpoint. Additionally, although Figures 3-5 are drawn to scale, other relative dimensions can be used if desired.

[0037] The calibration phantom holder 300 can be made of a material such as PVC or E. The calibration phantom holder 300 can include a vertical member 304 and a horizontal member 302. The vertical member 304 can be a slab positioned at a right angle to the horizontal member 302. When the calibration phantom holder 300 is installed in the PCCT imaging system 100, the horizontal member 302 can be parallel to the floor.

[0038] The horizontal member 302 can be configured to support the weight of one or more slabs that can be attached to the calibration phantom holder 300 during the calibration process. The horizontal member 302 can include a rectangular top surface 303 that can have a length of 40 cm to 60 cm and a width of 45 cm to 70 cm, in one example. The top surface 303 can include a first top surface 319, a second top surface 318, a third top surface 320, and a fourth top surface 322 that span the x-y plane at a first position in the z-axis. These top surfaces can have the same extent in the y-axis as the horizontal member 302, but different widths in the x-axis. For example, the first top surface 319 can be significantly narrower than the second top surface 318, the third top surface 320, and the fourth top surface 322. In some examples, the second top surface 318, the third top surface 320, and the fourth top surface 322 can have equal widths that can match the width of the calibration phantom. The fourth top surface 322 can include a first threaded insert pocket 324 and a second threaded insert pocket 326, which can be configured to receive threaded inserts. The first threaded insert pocket 324 and the second threaded insert pocket 326 can extend from the top surface 322 in the −z direction, but do not have to extend entirely through the horizontal member 302 along the z axis. In other embodiments of the calibration phantom holder 300, the threaded insert pockets can extend in the +z direction from the bottom surface of the horizontal member 302. FIG. 16 shows an exemplary threaded insert 1602, which can be placed in any of the threaded insert pockets 324, 326. The threaded insert 1602 includes a threaded portion 1604 for receiving a bolt or other threaded fastener for connecting, for example, the horizontal member 302 and the vertical member 304 of the calibration phantom holder 300. The exemplary threaded insert 1602 is shaped to correspond to the shape of the threaded insert pockets 324, 326 into which the threaded insert is disposed.That is, the length dimension 1606, width dimension 1608, and depth dimension 1610 of the threaded insert correspond to the length dimension, width dimension, and depth dimension of the threaded insert pockets 324, 326 such that the threaded insert 1602 can be press-fit into the threaded insert pockets 324, 326. In other examples, the threaded insert pockets and corresponding threaded inserts may have different shapes (circular, hexagonal, etc.).

[0039] The top surface 303 may further include a first slot 312, a second slot 314, and a third slot 316. These slots may be parallel to each other and to the y-axis. The slots are 0.5 to 3 cm deep in the -z direction from the top surface 303. In the example calibration phantom holder 300, the slots have a dovetail shape, but other configurations (e.g., a T-slot shape) are possible. The calibration phantom may have a tab configured to mate with the slot so that the phantom can slide into the slot from a side (e.g., first side 310). In one example, a detent may be provided within the slot, which prevents the calibration phantom from changing its position once inserted. An example of a detent is shown in FIG. 15. The slots are arranged such that a calibration phantom inserted into the first slot 312 is supported by the second upper surface 318, a calibration phantom inserted into the second slot 314 is supported by the third upper surface 320, and a calibration phantom inserted into the third slot 316 is supported by the fourth upper surface 322.

[0040] The fourth upper surface 322 may include a first dovetail entry section 328 and a second dovetail entry section 330. The dovetail entry section may be a three-sided entry section located at an edge 329 of the fourth upper surface 322 closest to the vertical member 304. The dovetail entry section may extend in the z-direction from the top surface 303 a distance less than the height of the horizontal member 302. The first dovetail entry section 328 may include a first joint 332, and the second dovetail entry section 330 may include a second joint 334. These joints may allow the horizontal member 302 to be joined to the vertical member 304 at an orthogonal angle.

[0041] In addition to the top surface 303, the horizontal member 302 can include a front surface 306, a bottom surface 506, a first side surface 310, a second side surface 406, and a back surface 410. In one embodiment, the front surface 306 can be a first front surface. The front surface 306 and the back surface 410 have the same shape and lie in the x-z plane, separated by the extent of the calibration phantom holder 300 in the x-axis direction. The shape of the front surface 306 is shown in FIG. 3. The front surface 306 can be hexagonal, having a front top edge 358, a front bottom edge 360, a first front side edge 362, a second front side edge 364, a third front side edge 366, and a fourth front side edge 368. The front top edge 358 can be a horizontal edge parallel to the y-axis that connects the front surface 306 to the first top surface 319. The front bottom edge 360 ​​can be a horizontal edge parallel to the y-axis that joins the front surface 306 to the bottom surface 506. The front bottom edge 360 ​​can be shorter than the front top edge 358. The first front side edge 362 can be a straight edge along the z-axis that joins the front surface 306 to the first side surface 310. The first front side edge 362 can be joined to the front top edge 358 at a right angle. The first front side edge 362 can be shorter than the distance between the front bottom edge 360 ​​and the front top edge 358. The second front side edge 364 can join the front surface 306 to the second side surface 406. Furthermore, the second front side edge 364 can be joined to the first front side edge 362 and the front bottom edge 360 ​​at an obtuse angle. The obtuse angle can be between 110 degrees and 150 degrees. The third front side 366 can be symmetrical to the first front side 362, and the fourth front side 368 can be symmetrical to the second front side 364. The third front side 366 can be bonded to the same side as the first side 310, and the fourth front side 368 can be bonded to the same side as the second side 406.

[0042] The bottom surface 506 may be a rectangular plane having a length in the y-axis direction that is shorter than the length of the top surface 303 in the y-axis direction and a width in the x-axis direction that is equal to the width of the horizontal member 302 in the x-axis direction. The first side surface 310 may be a rectangular plane in the xz plane having a width in the x-axis direction that is equal to the length of the horizontal member 302 in the x-axis direction and a height in the z-axis direction that is shorter than the height of the horizontal member 302 in the z-axis direction. The first side surface 310 may connect the front surface 306 to the back surface 410 and connect the top surface 303 to the second side surface 406. The first side surface 310 may further include dovetail sections of the first slot 312, the second slot 314, and the third slot 316. The second side surface 406 may be a rectangular plane connecting the first side surface 310 to the bottom surface 506 and connecting the front surface 306 to the back surface 410. The second side 406 has a length in the x-axis direction equal to the length of the horizontal member 302, and the second side 406 has a width that allows the first side 310 to be joined to the bottom surface 506 at an obtuse angle.

[0043] In one embodiment, the second side 406 can include a first side opening 502 and a third threaded insert pocket 504. The first side opening 502 extends from the second side 406 in the z-direction. The first side opening 502 can be provided in the horizontal member 302 at a depth such that the first side opening 502 does not penetrate the top surface 303. However, the first side opening 502 can be deep enough to allow a person handling the calibration phantom holder 300 to insert a finger into the first side opening 502 to grasp the horizontal member 302. The first side opening 502 can be long enough in the x-axis and y-axis directions to accommodate a person's finger and can have rounded edges so that a person can easily grasp the first side opening 502. The third threaded insert pocket 504 can be provided in the horizontal member 302 at a depth such that the third threaded insert pocket 504 does not penetrate the top surface 303. In some examples, there may be a fourth threaded insert pocket that is symmetrical about the X-axis to the third threaded insert pocket 504. In some examples, the third threaded insert pocket 504 and the fourth threaded insert pocket may be used in place of the first threaded insert pocket 324 and the second threaded insert pocket 326.

[0044] The vertical member 304 can be made of the same material as the horizontal member 302. The vertical member can include a front surface 336, a back surface 402, a top surface 338, a first side surface 344, a second side surface 346, a third side surface 516, and a fourth side surface 518. The vertical member 304 lies in the zy plane, and the width of the vertical member 304 in the x-axis direction is less than the depth of the horizontal member 302 in the z-axis direction. In one embodiment, the front surface 336 can be a second front surface. The length of the top surface 338 of the vertical member 304 in the y-axis direction can be equal to the length of the horizontal member 302 in the y-axis direction. The top surface 338 can be perpendicularly joined to the first side surface 344 by a first rounded corner 342, and the top surface 338 can be perpendicularly joined to the second side surface 346 by a second rounded corner 340. The first side 344 and the second side 346 can be symmetrical. The front surface 336 can be planar in the zy-plane. The front surface 336 can include a first opening 350 and a second opening 352. The first opening 350 and the second opening 352 can be identical and symmetrical about a midline along the z-axis of the vertical member 304. The first opening 350 and the second opening 352 can be rounded openings that extend into the vertical member 304 a distance less than the depth of the vertical member 304 in the x-direction. The front surface 336 can also include a first handle opening 348 and a second handle opening 354. The first handle opening 348 and the second handle opening 354 can be identical and symmetrical about a midline along the z-axis of the vertical member 304. The handle openings can pass completely through the vertical member 304. The handle opening has a length along the z-axis and a width along the y-axis, allowing a person to insert their fingers into the opening to hold the calibration phantom holder 300. The handle opening can have rounded edges to provide an easy grip.

[0045] The vertical member 304 may include a surface 356 recessed relative to the front surface 336, as shown in FIG. 3 . When the vertical member 304 and horizontal member 302 are coupled, the surface 356 may be in surface contact with the back surface 410 of the horizontal member 302, as shown in FIGS. 5-6 . One method of coupling the vertical member 304 to the horizontal member 302 includes sliding the first joint 332 and the second joint 334 of the horizontal member 302 into the first dovetail entry portion 328 and the second dovetail entry portion 330, respectively, as shown in FIG. 3 . FIG. 4 illustrates an uncoupled configuration in which the horizontal member 302 is spaced apart from the vertical member 304. In some embodiments, as shown in FIG. 4 , the vertical member 304 may include a recess 357. The connection between the vertical member 304 and the horizontal member 302 may be secured by inserting a threaded insert into a threaded insert pocket (such as the first threaded insert pocket 324, the second threaded insert pocket 326, the third threaded insert pocket 504, or the fourth threaded insert pocket (not shown)) in the horizontal member 302. A bolt may be coupled to the threaded insert to couple the vertical member 304 to the horizontal member 302. As shown in FIGS. 5 and 6 , the bolt may be used to bring the vertical member 304 into contact with the horizontal member 302. The back surface 402 of the vertical member 304 may include a convex portion 520 and a flat portion 522. The flat convex portion 520 may include a portion of the back surface 402 that protrudes further in the +x direction than the flat portion 522. The convex portion may be formed from a first rectangular portion 524 surrounding the first handle opening 348 and a second rectangular portion 526 surrounding the second handle opening 354. The first rectangular portion 524 may be connected to the second rectangular portion 526 by a third rectangular portion 528. The third rectangular portion 528 may be parallel to the top surface 338. The back surface 410 may further include a first joint cover 530 and a second joint cover 532. The joint covers may include convex portions of the back surface 410 that protrude in the +x-axis. The first joint cover 530 may surround the location of the second joint 334, and the second joint cover 532 may surround the location of the first joint 332.The back surface 402 can further include a plurality of coupling openings, including a first coupling opening 508, a second coupling opening 510, a third coupling opening 512, and a fourth coupling opening 514. These coupling openings can be circular openings that extend from the back surface 402 to the front surface 336 of the vertical member 304. The coupling openings can have a diameter sized to accommodate a screw or other fastener for securing the vertical member 304 to the horizontal member 302. In some embodiments, the coupling openings can be internally threaded so that the vertical member 304 can be coupled to the screw. The back surface 402 can further include a set of three openings (a first opening 540, a second opening 542, and a third opening 544). In some embodiments, the vertical member 304 can include a hanger 404, as shown in FIG. 4 . The hanger 404 can include a hook extending from the back surface in the +x direction and extending in the −z direction. A hanger 404 can be used to connect the vertical member 304 to the mounting plate of the table interface.

[0046] FIG. 6 shows the calibration phantom holder 300 coupled to a cradle clamp holder 600. Some components of the calibration phantom holder 300 introduced in FIGS. 3-5 may not be labeled and / or shown again in FIG. 6 for the sake of brevity. The cradle clamp holder 600 is an example of the support system 116 described above with reference to FIG. 1. The cradle clamp holder 600 includes a flat body portion 602. The flat body portion 602 may have an elongated rectangular shape. The flat body portion 602 is a single continuous body. The flat body portion 602 may be formed from a combination of metal, plastic, and / or rigid material. The flat body portion 602 may include one or more cutouts 612 extending through the thickness of the flat body portion 602. The one or more cutouts 612 may be provided to reduce the weight of the cradle clamp holder 600 while maintaining the structural integrity of the flat body portion 602. The planar body portion 602 further includes one or more through-holes 616 that extend through the thickness of the planar body portion 602. The one or more through-holes 616 are located near the second end 696 of the cradle clamp holder 600 (and therefore of the planar body portion 602). Further, the through-holes 616 are located near the first end 692 of the cradle clamp holder 600. Each through-hole 616 can be used to position a leveling portion of the planar body portion 602 (such as a level sensor or level line configured to identify the position of the cradle clamp holder 600 in space).

[0047] The cradle clamp holder 600 includes a first leveling foot 622a and a second leveling foot 622b, each of which includes a rod 624 passing through a hole 616 that extends through the thickness of the planar body 602 perpendicular to the plane of the planar body 602. Each of the rods 624 and holes 616 is threaded so that the rod can be rotatably coupled to the hole 616. The position of the planar body 602 along the length of each rod 624 of the first leveling foot 622a and the second leveling foot 622b is independently adjustable, as described further herein. The first leveling foot 622a and the second leveling foot 622b have the same configuration, and therefore, a description of the first leveling foot 622a should be understood to also describe the second leveling foot 622b, unless otherwise noted. Each leveling foot can include a rotatable adjustment head.

[0048] Rotating the adjustment head of the first leveling foot 622a can move the flat body portion 602 along the length of the rod 624 of the first leveling foot 622a. For example, rotating the adjustment head in a clockwise direction can move the first leveling foot 622a (e.g., rod 624) downward relative to the flat body portion 602. Moving the first leveling foot 622a downward relative to the flat body portion 602 lengthens the length of the rod 624 at the lower portion of the flat body portion 602 and shortens the length at the upper portion of the flat body portion 602. Increasing the length of the rod 624 at the lower portion of the flat body portion 602 can increase the vertical distance between the flat body portion 602 and the surface on which the flat body portion 602 is placed (e.g., the cradle of an imaging system).

[0049] The cradle clamp holder 600 further includes a coupling clamp 640 at a first end 692 of the cradle clamp holder 600. The coupling clamp 640 includes a handle 656 that can be used to hold, carry, adjust, and position the cradle clamp holder 600. The coupling clamp 640 is formed of a support beam 644 having a first clamp 642 a and a second clamp 642 b. The support beam 644 is disposed perpendicular to the length of the planar body portion 602, with the first clamp 642 a and the second clamp 642 b located on opposite sides of the planar body portion 602. The first clamp 642 a and the second clamp 642 b are coupled to the support beam 644 at a pivot joint 646. The first clamp 642 a and the second clamp 642 b are adjustable between a first position and a second position. The first clamp 642a and the second clamp 642b can be used to secure the cradle clamp holder 600 to a surface (such as a cradle of the imaging system 100) by adjusting between a first position and a second position. The first clamp 642a and the second clamp 642b have the same configuration, and therefore, a description of the first clamp 642a should be understood to also describe the second clamp 642b, unless otherwise specified.

[0050] The coupling clamp 640 is coupled to the planar body portion 602 at a first end 692 of the planar body portion 602 via a swivel joint 660. The swivel joint 660 can selectively couple the coupling clamp 640 to the planar body portion 602. The swivel joint 660 allows the planar body portion 602 to rotate about a central axis relative to the coupling clamp 640. In other words, the coupling clamp 640 is stationary (e.g., does not move relative to the central axis), and the planar body portion 602 can tilt left and right relative to the central axis. The swivel joint 660, in cooperation with adjustments of the first leveling foot 622a and the second leveling foot 622b, can level the cradle clamp holder 600.

[0051] An attachment plate 630 configured to support a subject to be imaged is coupled directly or indirectly to the planar body portion 602 at a second end 696 opposite the first end 692 of the planar body portion 602. For example, the attachment plate 630 may be directly coupled to the planar body portion 602 by welding, brazing, or other bonding method, which may result in the attachment plate 630 and the planar body portion 602 being a single, continuous part. In another embodiment, the attachment plate 630 is indirectly coupled to the planar body portion 602, for example, via one or more adjustable rods. The one or more adjustable rods may be removably attached to the planar body portion 602 at a first end of the rod and to the attachment plate 630 at a second end of the rod. For example, one or more adjustable rods can be attached to the planar body portion 602 and the attachment plate 630 via a snap fit, a threaded attachment, and / or other removable attachment mechanism. The one or more rods can be interchangeable and therefore adjustable. The attachment plate 630 can have a variety of configurations that enable the cradle clamp holder 600 to support a subject to be imaged via the attachment plate 630 and / or via mounting attachments selectively coupled to the attachment plate 630. In the exemplary cradle clamp holder 600 shown in FIG. 6 , the attachment plate 630 includes a plurality of cutouts 632 and through-holes 634 that can be included to reduce the weight of the cradle clamp holder 600 while maintaining the structural integrity of the attachment plate 630. The cutouts 612 and through-holes 616 provide features through which a mounting attachment can be coupled to the attachment plate 630. In one embodiment, fasteners can be inserted through the through-holes 634 or cutouts 632, and the fasteners can couple to mating holes in the vertical member 304 to couple the attachment plate 630 to the back surface 402 of the vertical member 304.In some embodiments, the attachment plate 630 can be coupled to the back surface 402 of the vertical member 304 by a hook (such as the hanger 404 shown in FIG. 4).

[0052] Because the attachment plate 630 is coupled to the vertical member 304, movement of the planar body portion 602 translates into movement of the vertical member 304 and, therefore, into movement of the calibration phantom holder 300. Adjusting the vertical position of the planar body portion 602, for example, by adjusting one or more of the first leveling foot 622a and the second leveling foot 622b, also adjusts the vertical position of the vertical member 304.

[0053] Coupling clamp 640 is configured to engage an imaging system cradle to center cradle clamp holder 600 relative to the cradle and fix the position of flat body portion 602 relative to the cradle. First leveling foot 622a, second leveling foot 622b, and swivel joint 660 are configured to adjust the leveling of cradle clamp holder 600 when cradle clamp holder 600 is placed in the cradle.

[0054] Figure 7 is a schematic diagram showing a calibration phantom holder 700 supporting a phantom 702. Calibration phantom holder 700 may be a holder similar to calibration phantom holder 300 of Figures 3-6. Components in calibration phantom holder 700 that are common to calibration phantom holder 300 are numbered the same and, for the sake of brevity, will not be described again in Figure 7.

[0055] The phantom 702 may be rectangular and have a front surface 704 extending in the x-z plane, a back surface identical to the front surface 704, a top surface 710 and a bottom surface 712 extending in the x-y plane, and a first side surface 714 and a second side surface 716 extending in the y-z plane. The first side surface 714 and the second side surface 716 are rectangular and may have a length in the y-axis direction that is equal to or less than the length of the top surface 303 in the y-axis direction. The first side surface 714 and the second side surface 716 have a height in the z-axis direction. The height of the phantom 702 may be within a range (e.g., a height ranging from 1 cm to 10 cm), allowing an engineer to stack one or more phantom combinations during the calibration process. The length of the top surface 710 and the bottom surface 712 in the y-axis direction may be equal to the length of the first side surface 714 and the second side surface 716 in the y-axis direction. The width of the top surface 710 and the bottom surface 712 in the x-axis direction may be equal to the width of the fourth top surface 322. The bottom surface 712 may be in surface contact with the fourth top surface 322.

[0056] The bottom surface 712 may include a tab 708. The tab 708 may extend from the bottom surface 712 in the negative z-direction and may be located a short distance from the second side surface 716 in the positive x-direction. A portion of the bottom surface 712 of the phantom 702 on the negative x-direction side from the tab 708 may be in surface contact with the third top surface 320. The tab 708 may extend the length of the phantom 702 in the y-axis direction, and may have a shape, width in the x-axis direction, and height in the z-axis direction that allow the tab 708 to couple with the third slot 316. In the example shown in FIG. 7 , the tab 708 has a rectangular outline that is identical to the rectangular outline of the third slot 316. However, in other embodiments, the third slot 316 may have a dovetail-shaped outline, and the tab 708 may have a dovetail-shaped outline that matches the outline of the third slot 316.

[0057] In the example shown in FIG. 7 , phantom 702 is coupled to third slot 316. However, first slot 312, second slot 314, and third slot 316 can be identical in shape and size, allowing a phantom (such as phantom 702) to be inserted into any of the slots. Top surface 710 includes top surface slot 706, which is identical in shape and size to third slot 316. A second phantom similar to phantom 702, including a tab (such as tab 708), can be stacked on top surface 710, and the second phantom can be secured by inserting the tab of the second phantom into top surface slot 706 of phantom 702. In this manner, a stack of one or more phantoms can be formed on fourth top surface 322. The phantoms in the stack can be made of different materials, and in some examples, the phantoms can have different heights in the z-axis direction. However, each phantom includes a tab (such as tab 708) and a top slot (such as top slot 706), allowing multiple phantoms to be stacked in any order. Figure 7 includes an alternative example of a connection between vertical member 304 and horizontal member 302. In this example, vertical member 304 is stacked on top of horizontal member 302, and vertical member 304 can be connected to horizontal member 302 by a fastening method such as mating slots and tabs or by fasteners such as bolts or screws.

[0058] Figure 8 illustrates an exemplary calibration phantom holder 800 that includes guide portions to allow the calibration phantom to be placed in a repeatable position. Calibration phantom holder 800 can be similar to calibration phantom holder 300 of Figures 3-6. Components in calibration phantom holder 800 that are common to calibration phantom holder 300 are numbered the same and, for the sake of brevity, will not be described again in Figure 8.

[0059] The calibration phantom holder 800 includes a plurality of rods 810. The rods 810 may include a first rod 802, a second rod 804, a third rod 806, and a fourth rod 808. The first rod 802 and the second rod 804 may be coupled to the second upper surface 318. The first rod 802 and the second rod 804 may be positioned at the center of the second upper surface 318 relative to the width of the second upper surface 318 in the x-axis direction, and the first rod 802 and the second rod 804 may be positioned equally spaced from the center of the second upper surface 318 relative to the length of the second upper surface 318. The third rod 806 and the fourth rod 808 can be positioned at the center of the third top surface 320 relative to the width of the third top surface 320 in the x-axis direction, and the third rod 806 and the fourth rod 808 can be positioned equally spaced from the center of the third top surface 320 relative to the length of the third top surface 320 in the y-axis direction. In some embodiments, rods can be positioned in a similar manner on the fourth top surface 322. The height of the rod 810 in the z-axis direction can be equal to or greater than the height of the stack of phantoms placed on the top surface 303. The rod 810 can be cylindrical or a rectangular prism of other shapes. The rod 810 can have a width smaller than its height. The rod can be configured to couple to mating holes in one or more phantoms. The rod can be inserted into the holes of one or more phantoms stacked on the top surface 303 of the calibration phantom holder 300 to stabilize the stack. In some cases, the rod may be made of acrylic, PVC, or PE.

[0060] FIG. 9 shows a schematic diagram 900 of a cross-sectional view of an exemplary set of rods inserted into an exemplary phantom 912. The phantom 912 can be composed of three segments. There is a first segment 904 separated from a second segment 902 by a first opening 914, and a third segment 906 separated from the second segment 902 by a second opening 916. There is a first rod 908 inserted into the first opening 914, and there is a second rod 910 inserted into the second opening 916. The height of the rod is greater than the height of the phantom 912, and when the rod is inserted into the opening, it penetrates the top and / or bottom surfaces of the phantom 912. The openings can be sized to accommodate the size and shape of the rods to allow for tolerances that allow for easy insertion and removal of the rods. When rods are inserted into one or more phantoms, the rods prevent the phantom from moving during scanning, which can improve the clarity of the resulting images and calibrations.

[0061] 10 and 11 are diagrams of an exemplary phantom. The exemplary phantom can be used to calibrate a PCCT system, where the exemplary phantom is supported by a disclosed calibration phantom holder (such as the calibration phantom holder 300 shown in FIGS. 3-6 or the holder shown in FIGS. 7-8) and placed in the bore of the PCCT system. The exemplary phantom shown in FIGS. 10 and 11 is configured to mate with the channel of the horizontal member 302 of the calibration phantom holder 300 and can be slid in from the side in an insertion manner similar to the insertion of the phantom 702 described with respect to FIG. 7.

[0062] FIG. 10 is a diagram of a first example phantom 1000. FIG. 10 illustrates a Cartesian coordinate system 1001. In one embodiment, the z-axis of the coordinate system 1001 may be a vertical axis (e.g., parallel to the gravity axis), the y-axis of the coordinate system 1001 may be a longitudinal axis (e.g., horizontal axis), and / or the x-axis of the coordinate system 1001 may be a horizontal axis. However, the axes may be axes of other directions in other examples. Regarding direction, the direction of the arrows on the x-axis, y-axis, and z-axis may represent positive, and the opposite direction of the arrows on the x-axis, y-axis, and z-axis may represent negative. Filled circles represent arrows and axes pointing toward the viewpoint (or in a positive direction relative to the viewpoint). Unfilled circles may represent arrows and axes pointing away from the viewpoint (or in a negative direction relative to the viewpoint). Furthermore, while FIG. 10 is drawn to scale, other relative dimensions may be used as desired.

[0063] The first example phantom 1000 can have a base 1004. The base 1004 can be a trapezoidal cylinder with a bottom surface 1006 parallel to a top surface 1008. The length of the bottom surface 1006 in the y-axis direction can be shorter than the length of the top surface 1008. There are first and second angled sides 1010 and 1012 connecting the bottom surface 1006 to the top surface 1008. The base 1004 can have a trapezoidal flat front surface 1014. The base 1004 can have a width 1016 in the x-axis direction.

[0064] A first rectangular parallelepiped 1002 may be coupled to the top surface 1008 of the base 1004. The first rectangular parallelepiped may have the same width 1016 in the x-axis direction as the base 1004. The length of the first rectangular parallelepiped 1002 in the y-axis direction may be longer than the length of the base 1004 in the y-axis direction to form a protruding portion. A second rectangular parallelepiped 1018 may be coupled to the top surface of the first rectangular parallelepiped 1002. The second rectangular parallelepiped may have a length in the y-axis direction slightly longer than the first rectangular parallelepiped 1002 and the same width as the first rectangular parallelepiped 1002. A third rectangular parallelepiped 1020 is coupled to the top surface of the second rectangular parallelepiped 1018. The width of the third rectangular parallelepiped in the x-axis direction may be wider than the width of the second rectangular parallelepiped 1018 and the length in the y-axis direction may be wider than the width of the second rectangular parallelepiped 1018 in the y-axis direction. In one example, each layer (e.g., base 1004, first cuboid 1002, second cuboid 1018, etc.) of exemplary phantom 1000 may comprise a slab (e.g., one of the slotted slabs described with reference to FIG. 7). For example, one or more layers (e.g., slabs) may be added or removed during the calibration process based on the calibration method implemented by the technician.

[0065] FIG. 11 is a diagram of a second example phantom 1100. FIG. 11 illustrates a Cartesian coordinate system 1101. In one example, the z-axis of coordinate system 1101 may be a vertical axis (e.g., parallel to the gravity axis), the y-axis of coordinate system 1101 may be a longitudinal axis (e.g., horizontal axis), and / or the x-axis of coordinate system 1101 may be a horizontal axis. However, in other examples, the axes may be axes with other directions. Regarding direction, the direction of the arrows on the x-, y-, and z-axes may represent positive, and the opposite direction of the arrows on the x-, y-, and z-axes may represent negative. Filled circles represent arrows and axes pointing toward (or in a positive direction relative to) the viewpoint. Unfilled circles may represent arrows and axes pointing away from (or in a negative direction relative to) the viewpoint. Furthermore, while FIG. 10 is drawn to scale, other relative dimensions may be used as desired.

[0066] The second exemplary phantom 1100 can have a base 1102. The base 1102 can be a rectangular parallelepiped having a length in the y-axis direction, a width in the x-axis direction, and a height in the z-axis direction. A rectangular parallelepiped 1104 can be coupled to the top surface of the base 1102. The rectangular parallelepiped 1104 can be taller than the base 1102 in the z-axis direction, longer than the base 1102 in the y-axis direction, and wider than the base 1102 in the x-axis direction. In one example, the rectangular parallelepiped 1104 is composed of multiple layers, and each layer can be a slab having a different thickness, density, or other clinically relevant parameter.

[0067] A trapezoidal prism 1106 can be coupled to the top surface of the rectangular parallelepiped 1104. The trapezoidal prism can have a bottom surface 1110, and the length of the bottom surface 1110 in the y-axis direction is shorter than the length of the top surface 1108 in the y-axis direction. There are a first angled surface 1112 and a second angled surface 1114 that couple the top surface 1108 to the bottom surface 1110.

[0068] 12 and 13 are flow charts illustrating methods 1200 and 1300, respectively, for performing calibration of a PCCT system using a calibration phantom holder. Methods 1200 and 1300 are described with respect to calibration phantom holder 300 of Figures 3-6. The PCCT system is imaging system 100 or imaging system 200, which are described with reference to Figures 1-2, respectively.

[0069] In step 1202, the method 1200 includes attaching a calibration phantom holder to a support system of an imaging system. In one example, the calibration phantom holder can be coupled to a cradle clamp holder (such as cradle clamp holder 600). The cradle clamp holder allows the calibration phantom holder to be coupled to a cradle of a patient table of a PCCT system.

[0070] In step 1204, method 1200 may include preparing one or more calibration phantoms. To prepare the one or more calibration phantoms, in step 1206, method 1200 may include selecting a plurality of slotted slabs and inserting one or more of the plurality of slotted slabs into one or more parallel slots in a horizontal member of a calibration phantom holder. The plurality of slotted slabs may be made of different materials and may have different dimensions. A combination of slotted slabs may be selected and ordered to create a stack that reflects the clinical goals of the PCCT system and the corresponding characteristics of the stack used to calibrate the PCCT system. The method may further include arranging one or more slotted slabs of the plurality of slotted slabs in one or more horizontal sections and stacking one or more slotted slabs of the plurality of slotted slabs in the one or more horizontal sections into a vertical stack. Slabs may be slid into slots included in the top surfaces of other slabs to form the vertical stack. In some examples, rods can be inserted into openings in the slabs to provide stability to the vertical stack, such as in the example of calibration phantom holder 800 in Figure 8. The vertical stack of calibration phantoms can be formed on one or more of the top surfaces included in the top surface of the horizontal member of the calibration phantom holder.

[0071] In one example, one or more calibration phantoms can be prepared based on a calibration process. A controller (e.g., a computer or computing device 216) of the PCCT system automatically outputs the calibration process in response to a user selection. The calibration process can include user instructions displayed on a display device (e.g., display 232). For example, the user instructions can include the number of slotted slabs, slab dimensions, slab material, stacking order of the slabs, location on the horizontal member, etc. A human operator (e.g., a technician) can prepare one or more calibration phantoms according to the user instructions.

[0072] In step 1208, the method 1200 can include placing a calibration phantom holder into a bore of the imaging system. The calibration phantom holder can be coupled to a cradle of a patient table by a cradle clamp holder. The position of the patient table can be adjusted to move the calibration phantom holder into the bore of the imaging system. In step 1210, the method 1200 can include performing a calibration process according to the method described with respect to FIG. 13 .

[0073] Referring to FIG. 13 , a method 1300 is described in which calibration can be performed on a phantom assembled in a calibration phantom holder. In step 1302, method 1300 can include obtaining instructions for the calibration process. As described above, in response to a user selection, the controller of the PCCT system can automatically output the calibration process and display the calibration process on a display device of the PCCT system. In one example, the calibration process includes a scanning order of a vertical stack of the calibration phantom holder, which can be performed automatically. The calibration phantom holder includes multiple stacks, each of which can include multiple slotted slabs. The contents of each stack can be changed by removing one or more slabs between scans. The displayed calibration process can include instructions to be given to the technician during the scan, such as a plan for when and how to adjust the vertical stacks between scans (e.g., removing or adding slabs) and a plan for how many scans will be performed for each stack.

[0074] In step 1304, the method may include placing a calibration phantom (e.g., a vertical stack) in the path of the x-ray beam. This may include adjusting the position of the patient table so that one stack assembled in the calibration phantom holder is positioned in the path of the x-ray beam. In some examples, the patient table may be moved according to a predetermined method that takes into account the position of each stack relative to the patient table and automatically centers the selected stack according to the instructions obtained in step 1302.

[0075] In step 1306, the method can include scanning the vertical stack, which can include the PCCT system directing an x-ray beam toward the vertical stack. The x-ray beam is attenuated by a calibration phantom, and the attenuated x-ray beam is measured by a detector array. The measured response of the detector array to the attenuated x-ray beam is stored, and the data can be used to obtain one or more images of the calibration phantom. The obtained images can be analyzed and used to adjust settings of the PCCT system so that the PCCT system is calibrated.

[0076] In step 1308, method 1300 may include determining whether all slabs specified for removal in the instructions obtained in step 1302 have been removed. In some examples, the instructions obtained in step 1302 may include instructions to scan the entire stack of slabs, remove one or more slabs, and scan again. The instructions may further include incrementally removing slabs and scanning the stack. In step 1308, the method may include verifying that all phantoms have been removed from the stack, indicating that the calibration process performed on the stack is complete. In one example, a human operator may visually inspect the calibration phantom holder to determine whether all phantoms have been scanned according to the instructions obtained in step 1302 and provide feedback to a computing system that can control the scanning process. In another example, a computer or operating system connected to the PCCT system may determine whether all scans of the vertical stack have been completed. If, in step 1308, all of the specified calibration phantoms have not yet been removed, method 1300 may include step 1314. In step 1314, method 1300 may include a human operator removing one or more calibration phantoms from the stack according to the instructions obtained in step 1302. The instructions 1302 may be displayed to the operator via a monitor or other display, allowing the operator to adjust the composition of each stack according to the instructions between scans.

[0077] If all designated calibration phantoms have been removed in step 1308, method 1300 may include step 1310. In step 1310, method 1300 may include determining whether all designated stacks have been scanned. In one example, a computer or operating system coupled to the PCCT system may determine whether all designated stacks have been scanned. If all designated stacks have not been scanned in step 1310, method 1300 may include adjusting the position of the calibration phantom holder so that the designated stacks that have not yet been scanned are centered. This may be accomplished by moving the patient table. A preset position associated with the position of the patient table may be stored in the computer system to center each vertical stack within the x-ray beam. If all designated stacks have been scanned in step 1310, method 1300 may include step 1312. In step 1312, method 1300 may include indicating that the calibration scan is complete. The completion indication may be registered by a computer system coupled to the PCCT system and used to indicate that power may be turned off to the detector array or other portions of the PCCT system.

[0078] An exemplary calibration process according to the methods disclosed herein can include preparing a first calibration phantom including a first plurality of slotted slabs arranged in a first vertical stack and preparing a second calibration phantom including a second plurality of slotted slabs arranged in a second vertical stack. The second vertical stack can be positioned adjacent to the first vertical stack (e.g., positioned horizontally adjacent to the first vertical stack). The calibration process can include scanning the first calibration phantom and scanning the second calibration phantom. Thereafter, the calibration process can include preparing a third calibration phantom including a third plurality of slotted slabs arranged in the first vertical stack (the third calibration phantom can be prepared by removing one or more slotted slabs or adding one or more slotted slabs to the first calibration phantom), and scanning the third calibration phantom.

[0079] Figure 14 shows an imaging system 1400 including an example of a cradle 120, a support system 116, and a calibration phantom holder 300 that supports one or more calibration phantoms 1402. Some components of the imaging system 1400 used with respect to Figures 1-6 are not labeled and / or described again in Figure 14 for the sake of brevity.

[0080] In this embodiment, calibration phantom holder 300 is coupled to support system 116, which is itself supported by cradle 120 on table 114. Calibration phantom holder 300 can hold one or more calibration phantoms 1402, each containing one or more slabs. As this embodiment illustrates, calibration phantom holder 300 has an open, dish-like design, allowing multiple vertical stacks of slabs to be arranged horizontally side-by-side. The stacked holder can then be placed into bore 124, and each vertical stack can be scanned. Because the slabs are accessible from both sides of the holder, individual slabs can be easily changed, which can include sliding one or more slabs off and on one or more vertical stacks, as described above. Calibration phantom holder 300 is sturdy and can support the considerable weight required for slab phantom calibration procedures. At the same time, the overall footprint of the calibration phantom holder 300 is small enough to fit within the circumference of the bore.

[0081] FIG. 15 shows an image of an exemplary detent 1502. The detent 1502 can have a threaded body 1504. The threaded body 1504 can be cylindrical and can have raised threads extending around the circumference of the cylindrical body. The threaded body 1504 can be configured to be securely inserted into a channel, such as the first slot 312 described with respect to FIG. 3. The threaded body can have a length 1506 that is parallel to the y-axis when the detent 1502 is inserted into the channel. The detent 1502 can include a rounded cap 1508 coupled to the circular surface of the threaded body 1504. The rounded cap 1508 can be hemispherical and made of metal or plastic. The rounded cap 1508 can be configured to contact a phantom (such as phantom 702) when the phantom is inserted into the channel. The threaded body 1504 can prevent the detent from shifting position within the groove when the phantom is inserted, and therefore can prevent the phantom from being inserted past the position of the rounded cap 1508 within the groove, thereby ensuring that the phantom is inserted in the same position within the channel for each scan.

[0082] Thus, by providing a calibration phantom holder that supports easily interchangeable modular calibration phantoms, the disclosed approach improves the efficiency of PCCT system calibration over existing approaches.

[0083] Although a photon-counting computed tomography (PCCT) system is described by way of example, it should be understood that the present technology is also useful when applied to other x-ray imaging modalities having photon-counting detectors, such as x-ray angiography systems, x-ray tomosynthesis systems, x-ray mammography systems, x-ray fluoroscopy systems, x-ray interventional systems, x-ray C-arm systems, etc. This description of the PCCT imaging modality is provided merely as an example of one suitable imaging modality.

[0084] The present disclosure also provides a support for a calibration phantom holder for an imaging system. The calibration phantom holder includes a horizontal member including a plurality of parallel slots on an upper surface of the horizontal member, each parallel slot configured to support one or more calibration phantoms, and a vertical member vertically coupled to the horizontal member, the vertical member configured to couple to a support system of the imaging system. In a first embodiment of the system, the calibration phantom holder includes a non-metallic material. In a second embodiment of the system, which optionally includes the first embodiment, the one or more calibration phantoms include slotted slabs. In a third embodiment of the system, which optionally includes one or both of the first and second embodiments, the horizontal member is configured to support multiple slotted slabs arranged vertically one above another. In a fourth embodiment of the system, which optionally includes one or more of the first through third embodiments, the horizontal member is configured to support multiple slotted slabs arranged horizontally side by side. In a fifth embodiment of the system, optionally including one or more of the first through fourth embodiments, the horizontal member is configured to support a plurality of slotted slabs arranged horizontally side-by-side and vertically stacked. In a sixth embodiment of the system, optionally including one or more of the first through fifth embodiments, each parallel slot of the plurality of parallel slots includes one or more detents. In a seventh embodiment of the system, optionally including one or more of the first through sixth embodiments, each parallel slot of the plurality of parallel slots has a dovetail shape. In an eighth embodiment of the system, optionally including one or more of the first through seventh embodiments, the vertical member includes one or more openings configured to act as handles and is configured to couple to a cradle clamp holder, and the horizontal member includes one or more openings configured to act as handles.In a ninth embodiment of the system optionally including one or more of the first to eighth embodiments, the horizontal member includes a first front surface and a back surface, the first front surface and the back surface are hexagonal, the vertical member includes a second front surface and a face, the face is recessed relative to the second front surface, and the face of the vertical member is vertically coupled to the back surface of the horizontal member. In a tenth embodiment of the system optionally including one or more of the first to ninth embodiments, the vertical member is vertically coupled to the back surface of the horizontal member by a first dovetail entry portion including a first joint and a second dovetail entry portion including a second joint, the back surface of the horizontal member includes a first joint cover and a second joint cover, the first joint cover is disposed at the first joint, and the second joint cover is disposed at the second joint.

[0085] The present disclosure also discloses a support for an imaging system. The imaging system includes a cradle, a support system, a calibration phantom holder including a horizontal member and a vertical member, the horizontal member having a plurality of parallel slots on an upper surface thereof and a vertical member vertically coupled to the horizontal member, and one or more calibration phantoms configured to be supported by the plurality of parallel slots. In a first embodiment of the system, the one or more calibration phantoms include slotted slabs having an upper slot and a lower tab, the lower tab configured to slide into a corresponding one of the plurality of parallel slots, and the upper slot configured to support a second calibration phantom. In a second embodiment of the system, which optionally includes the first embodiment, the slotted slabs are configured such that one slotted slab is vertically stacked on top of the other slotted slab and / or such that the slotted slabs are horizontally side-by-side. In a third embodiment of the system, which optionally includes one or both of the first and second embodiments, the slotted slab includes an opening configured to receive a rod inserted vertically into the stack, the rod being coupled to the horizontal member.

[0086] The present disclosure also supports a method for a calibration phantom holder for an imaging system. The method includes attaching a vertical member of the calibration phantom holder to a support system of the imaging system, preparing one or more calibration phantoms, placing the calibration phantom holder in a bore of the imaging system, and performing a calibration process using the one or more calibration phantoms. Preparing the one or more calibration phantoms includes selecting a plurality of slotted slabs and inserting one or more slotted slabs of the plurality of slotted slabs into one or more parallel slots of a horizontal member of the calibration phantom holder. In a first embodiment of the method, performing the calibration process includes sequentially scanning the one or more calibration phantoms. In a second embodiment of the method, which optionally includes the first embodiment, further includes placing one or more slotted slabs of the plurality of slotted slabs in one or more horizontal sections and stacking one or more slotted slabs of the plurality of slotted slabs in a vertical stack in the one or more horizontal sections. A third embodiment of the method, which optionally includes one or both of the first and second embodiments, further includes: preparing a first calibration phantom including a first plurality of slotted slabs arranged in a first vertical stack; preparing a second calibration phantom including a second plurality of slotted slabs arranged in a second vertical stack; scanning the first calibration phantom; scanning the second calibration phantom; and preparing a third calibration phantom including a third plurality of slotted slabs arranged in the first vertical stack, wherein the third calibration phantom is prepared by removing one or more slotted slabs from the first calibration phantom or adding one or more slotted slabs to the first calibration phantom; and scanning the third calibration phantom.In a fourth embodiment of the method, optionally including one or more of the first to third embodiments, or each embodiment, the calibration phantom holder comprises a substrate used in the calibration process.

[0087] FIGS. 3 through 11 and 14 through 16 illustrate example configurations with the relative positioning of various components. Where elements are shown as being in direct contact with or directly coupled to one another, they can, in at least one example, be said to be in direct contact with or directly coupled to one another. Similarly, elements shown as being contiguous or adjacent to one another can, in at least one example, be said to be contiguous or adjacent to one another, respectively. As an example, components in surface contact with one another can be said to be surface contacting components. As another example, elements positioned apart from one another, with only space between them and no other components present, can, in at least one example, be said to be such. As yet another example, elements shown above and below one another, opposite one another, or left and right of one another can be said to be such relative to one another. Furthermore, as shown in the figures, in at least one example, a top element or point on that element can be said to be the “top” of a component, and a bottom element or point on that element can be said to be the “bottom” of a component. As used herein, top / bottom, upper / lower, and above / below are relative to the vertical axis of the figure and can be used to describe the placement of elements in the figure relative to one another. For example, if an element is shown above another element, that element is, by way of example, vertically positioned above the other element. As yet another example, the shapes of elements shown in the figures can be referred to as having that shape (e.g., circular, rectilinear, planar, curvilinear, rounded, chamfered, angled, etc.). Furthermore, in at least one example, elements shown to intersect one another can be referred to as intersecting elements or intersecting one another. Furthermore, in one example, elements shown within or outside of another element can be referred to as such elements.

[0088] When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the element. The terms “first,” “second,” and the like do not denote order, quantity, or importance, but are used to distinguish one element from another. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. As used herein, when terms such as “connected,” “coupled,” and the like are used, one object (e.g., a material, element, structure, member, etc.) can be connected to or coupled to another object, regardless of whether the one object is directly connected to or coupled to the other object, or whether there are one or more intervening objects between the one object and the other object. In addition, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the referenced features.

[0089] In addition to the modifications described above, those skilled in the art will be able to devise numerous other variations and alternative structures without departing from the spirit and scope of the present description, and the claims are intended to cover such modifications and structures. Thus, while the above information has been described in particular detail with respect to what are presently considered to be the most practical and preferred embodiments, it will be apparent to those skilled in the art that numerous modifications in form, function, method of operation, and use (including, but not limited to, the present invention) are possible without departing from the principles and concepts described herein. Furthermore, the examples and embodiments herein are meant to be merely illustrative in all respects and should not be construed as limiting in any manner. [Explanation of symbols]

[0090] 102 Gantry 104 X-ray source 106 X-ray radiation beam 108 detector array 110 Image Processor Unit 112 Subject 114 Tables 116 Support System 118 first end 120 Cradle 122 Base 124 bore 200 Imaging System 202 detector elements 204 Subject 206 Center of rotation 208 Control Mechanism 210 X-ray controller 212 Gantry motor controller 214 Data Acquisition System (DAS) 216 Computing Devices 220 Operator Console 226 Table Motor Controller 230 Configurator 300 Calibration Phantom Holder 302 Horizontal Member 303 Top surface 304 Vertical Members 306 Front 310 First Aspect 312 First Slot 314 Second Slot 316 Third Slot 318 second upper surface 319 first upper surface 320 third upper surface 326 Second Threaded Insert Pocket 328 First dovetail inlet 329 Close Edge 330 Second dovetail inlet 332 First Joint 334 Second Joint 336 Front 338 Top surface 340 Corner 342 Corner 344 First Aspect 346 Second Aspect 348 First handle opening 350 First Opening 352 Second Opening 354 Second handle opening 356 sides 357 Recess 358 Front top edge 360 Front bottom 362 First front side 364 Second front side 366 Third front side 368 Fourth Front Side 402 Back 404 Hanger 406 Second Aspect 410 Back 502 first side opening 504 Third Threaded Insert Pocket 506 bottom 508 first coupling opening 510 second coupling opening 512 Third coupling opening 514 Fourth coupling opening 516 The Third Aspect 518 The Fourth Aspect 520 Convex part 522 Flat area 524 First rectangular part 526 Second rectangular section 528 Third Rectangular Section 530 First Joint Cover 532 Second Joint Cover 540 First Opening 542 Second Opening 544 Third Opening 600 Cradle Clamp Holder 602 Flat body part 612 Cutout 622a First Leveling Foot 622b Second Leveling Foot 624 Rod 630 Attachment Plate 632 Cutout 634 Through hole 640 Coupling Clamp 642a First Clamp 642b Second Clamp 644 Support Beam 646 Pivot Joint 656 Handle 660 Swivel Joint 692 First End 696 Second End 700 Calibration Phantom Holder 702 Phantom 704 Front 706 Top Slot 708 tabs 710 Top 712 bottom 714 First Aspect 716 Second Aspect 800 Calibration Phantom Holder 802 First Rod 804 Second Rod 806 Third Rod 808 Fourth Rod 810 Rod 902 Second Segment 904 First Segment 906 Third Segment 908 First Rod 910 Second Rod 912 Phantom 914 First Opening 916 Second Opening 1000 Phantom 1002 First Cuboid 1004 base 1006 bottom 1008 Top surface 1010 First angled side 1012 Second angled side 1014 Front 1016 width 1018 Second rectangular parallelepiped 1020 Third Cuboid 1100 Phantom 1101 Coordinate System 1102 Base 1104 Rectangular prism 1106 Column 1108 Top surface 1110 bottom 1112 First inclined surface 1114 Second Inclined Surface 1200 methods 1202 steps 1204 steps 1206 steps 1208 steps 1210 steps 1300 methods 1304 steps 1306 steps 1308 steps 1310 steps 1312 steps 1314 steps 1400 Imaging System 1402 Calibration Phantom 1502 Stopper 1504 Threaded Body 1506 length 1508 Cap 1602 Threaded Insert 1604 Threaded part 1606 Length dimension 1608 width dimension 1610 depth dimension

Claims

1. 1. A calibration phantom holder for an imaging system, comprising: a horizontal member including a plurality of parallel slots in a top surface of the horizontal member, each parallel slot of the plurality of parallel slots configured to support one or more calibration phantoms; and a vertical member coupled vertically to the horizontal member, the vertical member being configured to couple to a support system of the imaging system; a calibration phantom holder,

2. The calibration phantom holder of claim 1 , wherein the calibration phantom holder comprises a non-metallic material.

3. The calibration phantom holder of claim 1 , wherein the one or more calibration phantoms comprise a slotted slab.

4. 4. The calibration phantom holder of claim 3, wherein the horizontal member is configured to support a plurality of slotted slabs arranged vertically one on top of the other.

5. The calibration phantom holder of claim 3 , wherein the horizontal member is configured to support a plurality of slotted slabs arranged in a horizontal alignment.

6. 4. The calibration phantom holder of claim 3, wherein the horizontal member is configured to support a plurality of slotted slabs arranged horizontally side-by-side and vertically stacked.

7. The calibration phantom holder of claim 1 , wherein each parallel slot of the plurality of parallel slots includes one or more detents.

8. The calibration phantom holder of claim 1 , wherein each parallel slot of the plurality of parallel slots has a dovetail shape.

9. 2. The calibration phantom holder of claim 1, wherein the vertical member includes one or more openings configured to act as handles, the vertical member configured to couple to a cradle clamp holder, and the horizontal member includes one or more openings configured to act as handles.

10. 2. The calibration phantom holder of claim 1, wherein the horizontal member includes a first front surface and a back surface, the first front surface and back surface being hexagonal in shape, and the vertical member includes a second front surface and a face, the face being recessed relative to the second front surface, and the face of the vertical member being perpendicularly coupled to the back surface of the horizontal member.

11. 11. The calibration phantom holder of claim 10, wherein the vertical member is vertically coupled to a rear surface of the horizontal member by a first dovetail entry portion including a first joint and a second dovetail entry portion including a second joint, the rear surface of the horizontal member including a first joint cover and a second joint cover, the first joint cover being positioned at the first joint and the second joint cover being positioned at the second joint.

12. Cradle, Support system, a calibration phantom holder including a horizontal member and a vertical member, the horizontal member having a plurality of parallel slots on an upper surface of the horizontal member, and the vertical member being vertically coupled to the horizontal member; and one or more calibration phantoms configured to be supported by said plurality of parallel slots; an imaging system comprising:

13. 13. The imaging system of claim 12, wherein the one or more calibration phantoms include a slotted slab having an upper slot and a lower tab configured to slide into a corresponding slot of the plurality of parallel slots, and the upper slot configured to support a second calibration phantom.

14. 14. The imaging system of claim 13, wherein the slotted slabs are configured such that one slotted slab is stacked vertically on top of the other slotted slab and / or such that the slotted slabs are positioned horizontally side by side.

15. The imaging system of claim 13 , wherein the slotted slab includes an opening configured to receive a rod inserted vertically into the stack, the rod being coupled to the horizontal member.

16. 1. A method for a calibration phantom holder for an imaging system, comprising: attaching a vertical member of the calibration phantom holder to a support system of the imaging system; providing one or more calibration phantoms; placing the calibration phantom holder in a bore of the imaging system; and Performing a calibration process using one or more calibration phantoms Including, The method, wherein preparing one or more calibration phantoms includes selecting a plurality of slotted slabs and inserting one or more slotted slabs of the plurality of slotted slabs into one or more parallel slots of a horizontal member of the calibration phantom holder.

17. The method of claim 16 , wherein performing the calibration process includes sequentially scanning the one or more calibration phantoms.

18. 17. The method of claim 16, further comprising: arranging one or more slotted slabs of the plurality of slotted slabs in one or more horizontal sections; and stacking one or more slotted slabs of the plurality of slotted slabs in a vertical stack in the one or more horizontal sections.

19. 20. The method of claim 18, further comprising: preparing a first calibration phantom including a first plurality of slotted slabs arranged in a first vertical stack; preparing a second calibration phantom including a second plurality of slotted slabs arranged in a second vertical stack; scanning the first calibration phantom; scanning the second calibration phantom; and preparing a third calibration phantom including a third plurality of slotted slabs arranged in the first vertical stack, wherein the third calibration phantom is prepared by removing one or more slotted slabs from the first calibration phantom or adding one or more slotted slabs to the first calibration phantom.

20. The method of claim 16 , wherein the calibration phantom holder comprises a substrate used in the calibration process.

Images