Phantom for imaging systems

Abstract

This provides a holding system for phantoms used to calibrate imaging systems. [Solution] The retaining system includes at least one rod holder, the at least one rod holder including at least one opening configured to secure at least one rod of the phantom to the retaining system, and a fastener configured to secure the at least one rod holder to the body of the phantom.

Description

Technical Field

[0001] Embodiments of the subject matter disclosed herein relate to phantoms, and more particularly, to phantoms used for calibration of photon-counting computed tomography (CT) scanners.

Background Art

[0002] In a computed tomography (CT) imaging system, an electron beam generated by a cathode is irradiated toward a target in an X-ray tube. A fan-shaped or conical X-ray beam generated by electrons colliding with the target is irradiated toward a subject (such as a patient). The X-rays collide with an array of X-ray detectors after being attenuated by the subject to generate an image. An example of a CT system is a photon-counting CT (PCCT), in which the X-ray detector is a photon-counting detector that counts photons and provides spectral information. The PCCT system periodically performs a calibration process to acquire projection data of materials simulating various tissue densities of the human body. This calibration process can include performing a CT imaging procedure on an object called a phantom.

Summary of the Invention

[0003] In one example, a holding system for a phantom for calibrating an imaging system includes at least one rod holder, the at least one rod holder including at least one opening configured to secure at least one rod of the phantom to the holding system, and a fastener configured to secure the at least one rod holder to a body portion of the phantom.

[0004] The advantages, other advantages, and other features of this specification will become readily apparent from the embodiments for carrying out the invention described below, or by referring to the embodiments for carrying out the invention together with the drawings. It should be understood that the above summary is provided to introduce in a simplified form some of the concepts further described in the embodiments for carrying out the invention. The above summary is not intended to identify any important or essential features of the subject matter of the claims, and the scope of that subject matter is uniquely defined by the claims. Furthermore, the subject matter identified in the claims is not limited to embodiments that resolve the disadvantages described above or anywhere else in this disclosure. [Brief explanation of the drawing]

[0005] Various aspects of this disclosure can be further understood by reading the following embodiments for carrying out the invention and referring to the drawings. [Figure 1] This is a diagram of a computed tomography (CT) imaging system according to one or more embodiments of the present disclosure. [Figure 2] A schematic block diagram of an exemplary CT imaging system according to one or more embodiments of the present disclosure is shown. [Figure 3] A side view of an exemplary phantom including a rod holding system according to one embodiment of the present disclosure is shown. [Figure 4] Figure 3 shows a front view of an exemplary phantom according to one embodiment of the present disclosure. [Figure 5] Figure 3 shows a front view of the holder of the rod holding system of the phantom according to one embodiment of the present disclosure. [Figure 6] Figure 3 shows a perspective view of the portion of the phantom according to one embodiment of the present invention that is configured to receive the holder. [Figure 7] A rod holder coupled to a phantom, according to a second embodiment of the present invention, is shown. [Figure 8] This is a perspective view of a phantom having an end plate configured to hold a rod, according to one embodiment of the present invention. [Figure 9] A perspective view of a phantom including another rod holding system according to one embodiment of the present invention is shown. [Figure 10] This shows a first view of an exemplary opening used in combination with a loop for attaching the exemplary rod retaining system of Figure 9 to the phantom body, according to one or more embodiments of the present disclosure. [Figure 11] This is a second view of the opening in Figure 10 for attaching the rod retaining system of Figure 9 to the phantom body, according to one or more embodiments of the present disclosure. [Figure 12] Figure 9 shows the first side view of the Phantom. [Figure 13] Figure 9 shows a second side view of the Phantom. [Figure 14] Figure 9 shows a front view of the Phantom. [Figure 15] Figure 9 shows a rear view of the Phantom. [Figure 16] A perspective view of the rod holding system is shown. [Figure 17] An illustrative perspective view of a rod holding system is shown. [Figure 18] A perspective view of a rod holding system for a phantom according to one embodiment of the present disclosure is shown. [Figure 19] A perspective view of a rod holding system for a phantom according to one embodiment of the present disclosure is shown. [Figure 20] A perspective view of a rod holding system for a phantom according to one embodiment of the present disclosure is shown. [Figure 21] A perspective view of a rod holding system for a phantom according to one embodiment of the present disclosure is shown. [Figure 22] A perspective view of a rod holding system for a phantom according to one embodiment of the present disclosure is shown. [Figure 23] A perspective view of a rod holding system for a phantom according to one embodiment of the present disclosure is shown. [Figure 24] A perspective view of a rod holding system for a phantom according to one embodiment of the present disclosure is shown. [Figure 25]A perspective view of one embodiment of an iod rod configured to correspond to one or more phantoms of the present disclosure is shown. [Figure 26] A perspective view of another embodiment of an iod rod, including a rod holder configured for one or more of the multiple phantoms of the present disclosure, is shown. [Modes for carrying out the invention]

[0006] The subject matter and embodiments disclosed herein relate to phantoms for calibration scans of imaging systems (such as photon-counting computed tomography (PCCT) systems). Imaging systems (such as PCCT systems) may require periodic calibration scans, such as daily or weekly calibration scans, to compensate for gain drift caused by hardware (such as changes in X-ray focal position) or radiation degradation of the detector. Furthermore, PCCT systems can acquire spectral information, which can be used to generate biomedium discrimination (BMD) images. Calibrating a PCCT system may require scanning different solutions. Scanning these different solutions is cumbersome and can increase system costs.

[0007] Accordingly, embodiments relating to phantoms for calibrating imaging systems (such as PCCT systems, dual-energy CT (DECT) systems, or other CT systems) are disclosed herein. The phantoms disclosed herein may include a main part of the phantom (e.g., a phantom body) and one or more rods containing an iodine solution in each rod. The rods may be held in the phantom body by a retaining system or attached to the phantom body. In one example, the phantom body is a water phantom. The retaining system may include retaining parts formed in auxiliary parts configured to connect to a portion of the water phantom. Additionally or alternatively, the retaining system may include fastening devices configured to bond to the outside of the phantom body. The material in the rods may include a single element or a hybrid fluid containing several different elements (such as iodine or calcium). The material in the rods bonded to the outside of the phantom body may be different from the material held in the phantom body.

[0008] The surface of the phantom or phantom body of the present disclosure may include grooves or other feature portions that receive projections of a retaining system. Additionally or alternatively, the phantom may include end plates having one or more eyelets extending radially outward. The eyelets of these end plates may be aligned with the longitudinal axis of the phantom so that a rod is held by the eyelets. The exemplary end plates may be attached to the phantom body or formed integrally with the phantom body.

[0009] In another example, the holding system can be configured as a retrofit assembly and can be adapted to couple to an existing phantom configuration. The holding system can be configured to couple to the outside of the phantom or phantom body. The holding system can include a flexible material that allows the holding system and the iodine-containing rod to be easily coupled to the phantom body. Different embodiments of the holding system are described in detail below.

[0010] FIG. 1 shows an exemplary PCCT system 100 (also referred to as a photon-counting X-ray imaging system) configured for CT imaging using a photon-counting detector. Specifically, the PCCT system 100 is configured to image a subject 112 (patient, inanimate object, one or more manufactured parts, and / or foreign objects present in the body (such as dental implants, stents, and / or contrast agents)). The PCCT system 100 includes a gantry 102, and the gantry 102 can further include at least one X-ray source 104 configured to irradiate an X-ray radiation beam 106 (see FIG. 2) used to image the subject 112 placed on the table 114. Specifically, the X-ray source 104 is configured to irradiate the X-ray radiation beam 106 toward a detector array 108 disposed on the opposite side of the gantry 102. Although a single X-ray source 104 is shown in FIG. 1, in some embodiments, multiple X-ray sources and multiple detectors can be used to irradiate multiple X-ray radiation beams and acquire projection data at the same energy level or different energy levels corresponding to the patient. In some embodiments, the X-ray source 104 can perform dual-energy spectral imaging by rapid peak kilovolt (kVp) switching. In the embodiments described herein, the X-ray detector used is a photon-counting detector that can distinguish X-ray photons of different energies.

[0011] In certain embodiments, the PCCT system 100 further includes an image processor unit 110 configured to reconstruct an image of a target volume of the subject 112 using iterative or analytical image reconstruction methods. For example, the image processor unit 110 can reconstruct an image of a patient's target volume using an analytical image reconstruction technique such as filtered back projection (FBP). As another example, the image processor unit 110 may reconstruct an image of the target volume of the subject 112 using iterative image reconstruction techniques such as advanced statistical iterative reconstruction (ASIR), conjugate gradient (CG), maximum likelihood expectation maximization (MLEM), model-based iterative reconstruction (MBIR), etc. In some examples, the image processor unit 110 may use an analytical image reconstruction technique (such as FBP) in addition to an iterative image reconstruction technique.

[0012] In the configuration of some CT imaging systems, the X-ray source irradiates a conical X-ray radiation beam, which is defined with respect to the X-Y-Z orthogonal coordinate system and is generally referred to as the "imaging volume". 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 element array depends on the amount of attenuation of the X-ray radiation beam by the object. Each detector element of the array generates an individual electrical signal that is a measurement of the attenuation of the X-ray beam at the detector position. The attenuation measurements from all detector elements are acquired separately, and a transmission profile is generated.

[0013] In some CT systems, the X-ray source and the detector array rotate with the gantry within the imaging volume and around the object being imaged, and the angle at which the X-ray beam intersects the object is constantly changing. A group of X-ray radiation attenuation measurements (e.g., projection data) from the detector array at a certain gantry angle is called a "view". A "scan" of an object includes obtaining a set of views at different gantry angles, i.e., view angles, while the X-ray source and the detector make one rotation.

[0014] Figure 2 shows an exemplary imaging system 200 similar to the PCCT system 100 of Figure 1. According to one aspect of this disclosure, the imaging system 200 is configured to perform imaging of a subject 204 (e.g., subject 112 in Figure 1). In a particular scan, the subject may be a phantom. The phantom may be an object configured to be scanned by the PCCT system as part of the calibration process of the PCCT system. In one embodiment, the imaging system 200 includes a detector array 108 (see Figure 1). The detector array 108 further includes a plurality of detector elements 202, which sense an X-ray emission beam 106 (see Figure 2) passing through the subject 204 (e.g., a patient) to acquire corresponding projection data. In some embodiments, the detector array 108 may be manufactured in a multi-slice configuration including a plurality of columns of cells or detector elements 202, with one or more additional columns of detector elements 202 arranged in a parallel configuration to acquire projection data. Detector elements 202 are sometimes referred to as pixels or detector pixels.

[0015] In certain embodiments, the imaging system 200 can move to different angular positions around the subject 204 to acquire desired projection data. Thus, the gantry 102 and the components mounted on the gantry can be configured to rotate around a rotation center 206 to acquire projection data, for example, at different energy levels. Alternatively, in embodiments where the projection angle to the subject 204 changes over time, the mounted components can be configured to move along a general curve rather than along a portion of a circle.

[0016] 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 preprocessed and calibrated so that the data represents the line integral of the attenuation coefficient of the scanned subject 204. The processed data is generally called projection. In some embodiments, individual detectors or detector elements 202 of the detector array 108 may include photon counting detectors that record the interaction of individual photons in one or more energy bins.

[0017] The acquired set of projection data can be used for reference material discrimination (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 agents) or material density images for each reference material. The density maps or density images can be sequentially combined to form a 3D volumetric image of the reference material (e.g., bone, soft tissue, and / or contrast agent) within the acquired volume.

[0018] Upon reconstruction, the reference material image generated by the imaging system 200 reveals the internal features of the subject 204, represented by the densities of the two reference materials. To illustrate these features, the density image can be displayed. Conventional methods of diagnosing medical conditions (such as disease states) and, more generally, medical events, involve radiologists or physicians considering hard copies or displays of density images to identify features of interest. Such features may include lesions, the size and shape of specific anatomical structures or organs, and other features identifiable within the image based on the skills and knowledge of the individual healthcare professional.

[0019] In one embodiment, the imaging system 200 includes a control mechanism 208 that controls the movement of its components (such as the rotation of the gantry 102 and the operation of the X-ray source 104). In a particular embodiment, the control mechanism 208 further includes an X-ray controller 210 configured to supply power and timing signals to the X-ray source 104. Furthermore, the control mechanism 208 includes a gantry motor controller 212 configured to control the rotational speed and / or position of the gantry 102 based on imaging requirements.

[0020] In certain embodiments, the control mechanism 208 further includes a data acquisition system (DAS) 214, which samples analog data received from the detector elements 202 and converts the analog data into digital signals for subsequent processing. The DAS 214 can be further configured to selectively aggregate data from a subset of the detector elements 202 into a so-called macrodetector. The data sampled and digitized by the DAS 214 is transmitted through a slip ring 213 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 can be any type of non-temporary memory and may include, for example, a hard disk drive, a floppy disk drive, a compact disc read / write (CD-R / W) drive, a digital multipurpose disc (DVD) drive, a flash drive, and / or a solid-state storage drive.

[0021] Furthermore, the computing device 216 supplies commands and parameters to one or more of the DAS 214, X-ray controller 210, and gantry motor controller 212 to control system operations (such as data acquisition and / or data processing). In certain embodiments, the computing device 216 controls system operations based on operator input. The computing device 216 receives operator input, 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 touchscreen to allow the operator to specify commands and / or scan parameters.

[0022] Although Figure 2 shows only one operator console 220, multiple operator consoles may be coupled to the imaging system 200 to perform functions such as inputting or outputting system parameters, requesting examinations, plotting data, and / or displaying images. Furthermore, in certain embodiments, the imaging system 200 may be coupled to multiple displays, printers, workstations, and / or similar devices located locally or remotely within a facility or hospital, or in entirely different locations, via one or more configurable wired and / or wireless networks (such as the Internet and / or virtual private networks, wireless telephone networks, wireless local area networks, wired local area networks, wireless wide area networks, and wired wide area networks).

[0023] In one embodiment, for example, the imaging system 200 includes or is coupled to an image archive communication system (PACS) 224. In an exemplary embodiment, the PACS 224 is further coupled to a remote system (such as a radiology information system, a hospital information system, and / or an internal or external network (not shown)) so that operators in different locations can supply commands and parameters and / or access image data.

[0024] The computing device 216 operates the table motor controller 226 using commands and parameters supplied by the operator and / or defined by the system, and the table motor controller 226 controls the table 114. The table 114 can be an electrically operated table. Specifically, the table motor controller 226 can move the table 114 so that the subject 204 is properly positioned within the gantry 102 in order to acquire projection data corresponding to the target volume of the subject 204.

[0025] As described above, the DAS214 samples and digitizes the projection data acquired by the detector element 202. The image reconstructor 230 then performs high-speed reconstruction using the sampled and digitized X-ray data. In Figure 2, the image reconstructor 230 is shown as a separate entity, but in certain embodiments, the image reconstructor 230 may form part of the computing device 216. Alternatively, the image reconstructor 230 may not be present in the imaging system 200, and the computing device 216 may perform one or more functions of the image reconstructor 230. Furthermore, the image reconstructor 230 can be located locally or remotely and operably connected to the imaging system 200 using a wired or wireless network. In particular, in one exemplary embodiment, computing resources of a “cloud” network cluster can be used for the image reconstructor 230.

[0026] In one embodiment, the image reconstructor 230 stores the reconstructed image in a storage device 218. Alternatively, the image reconstructor 230 can transmit the reconstructed image to a computing device 216 to generate patient information useful for diagnosis and evaluation. In certain embodiments, the computing device 216 can transmit the reconstructed image and / or patient information to a display or display device 232 that is communicatively coupled to the computing device 216 and / or the image reconstructor 230. In some embodiments, the reconstructed image can be transmitted from the computing device 216 or the image reconstructor 230 to a storage device 218 for short-term or long-term storage.

[0027] Information can be transmitted between the components present in the gantry 102 and external devices (e.g., computing device 216 and / or image reconstructor 230) via the slip ring 213, thereby facilitating electronic communication of the rotating gantry. In some examples, the gantry and internal components (e.g., control mechanism 208, X-ray source 104, detector array 108) can be defined as a PCCT scanner as a whole, in which case the computing device 216 and image reconstructor 230 can be located outside the scanner.

[0028] Referring to Figures 3, 4, 5, and 6, these figures illustrate a first embodiment of the phantom 300 including an exemplary rod holding system 301. The phantom 300 may also include a body 304 made from a first material 302, the first material 302 may be housed within the body 304. A side view of Figure 3 shows a first rod holder 312 and a second rod holder 314 of the rod holding system 301. A rod 316 may extend from the first rod holder 312 to the second rod holder 314. The rod 316 may extend along the outer surface of the body 304, parallel to the central axis or longitudinal axis of the body.

[0029] The first rod holder 312 and the second rod holder 314 can be identical in shape and size to each other. The first rod holder 312 is connected to the outer surface of the main body 304 at the first end of the phantom 300. The second rod holder 314 can be connected to the outer surface of the main body 304 at the second end of the phantom 300 opposite to the first end. The rod 316 can extend from the rod holder 312 to the rod holder 314, along the length of the main body 304. In one example, the length of the rod 316 is equal to the total length of the main body 304.

[0030] In the examples illustrated herein, the main body 304 of the phantom is visible in areas where the first rod holder 312 and the second rod holder 314 are not attached to the main body. Thus, the first rod holder 312 and the second rod holder 314 can cover the main body 304 only in areas near the ends. In other examples, the phantom (including the main body) can be covered with protective material to prevent damage to the phantom, for example, when a technician is handling it.

[0031] Figure 4 shows a front view of the Phantom 300. As shown, the first rod holder 312 may include at least one surface corresponding to the shape of the main body 304. That is, in the example where the main body 304 is cylindrical, the surface of the rod holder 312 that contacts the main body 304 may include a curved shape that matches the curvature of the main body 304. As described above, the second rod holder 314 has a substantially similar structure to the first rod holder 312. Thus, the first rod holder 312 and the second rod holder 314 overlap tightly with the outer surface of the main body 304. In some examples, the shape of the first rod holder 312 or the second rod holder 314 can be changed depending on the difference in the position in the main body where the corresponding rod holders 312, 314 are joined, so that each rod holder 312, 314 includes at least one surface that contacts the main body and corresponds to the shape of the main body.

[0032] The first rod holder 312 includes an opening 318. The opening 318 may have a circular cross-sectional shape. In other embodiments, the opening may have a different shape (e.g., elliptical, semicircular, square, rectangular, etc.) or a combination of curved and flat surfaces corresponding to the surface of the rod. The rod 316 can be inserted into the opening 318. In one example, the opening 318 is adjacent to the body 304. In this case, the rod 316 is close to the body 304. In one example, the rod 316 may contact the surface of the body 304 when placed in the opening 318. In one example, the opening 318 may form an eyelet of the first rod holder 312, and the eyelet may be configured to receive and hold the rod 316. In one example, the body 304 may include a first material 302, and the rod 316 may include a second material, the second material of which may be different from the first material. In one example, the first material is non-iodine, and the second material is iodine. Therefore, the first material can be iodine-free, while the second material can be iodine-containing.

[0033] Figure 5 shows a front view of the first rod holder 312. The first rod holder 312 includes a projection 320 extending from the opening 318. This projection functions as a fastener (in combination with a notch 322, which will be described in more detail below) for attaching the exemplary first rod holder 312 to the main body 304 of the phantom 300. The exemplary projection 320 may have a circular shape. In some examples, additionally or alternatively, the projection 320 may have other shapes (such as a square, star, trapezoid, or other shape) without departing from the scope of disclosure.

[0034] Figure 6 shows a detailed view of the main body 304 at the position where the first rod holder 312 is coupled to the main body 304. The main body 304 may include a notch 322. The notch 322 may have a circular shape complementary to the projection 320 of the first rod holder 312. Alternatively, the notch 322 may be formed to correspond to another shape of the projection 320. The projection 320 can slide into the notch 322 so that the first rod holder 312 can be coupled to the main body 304.

[0035] The length of the notch 322 can be a value based on the length of the projection 320 of the first rod holder 312. In one example, the length of the notch 322 is equal to the length of the projection 320, so that the first rod holder 312 is flush with the front end of the first end of the phantom 300. In an alternative example, the length of the notch 322 corresponds to the length of the body 304 of the phantom 300, so that the first rod holder 312 and the second rod holder 314 can be connected to the notch at opposite ends of the body and aligned. Furthermore, the notch 322 can be used to fix the first rod holder 312 in place so that it is properly oriented to a desired position. The projection 320 can be inserted into the notch 322. The projection 320 engages with the notch 322 and can hold the first rod holder 312. In some examples, the phantom body 304 may include multiple notches 322, each notch 322 connecting with a projection on a rod holder (such as the first rod holder 312 and / or the second rod holder 314), thereby allowing multiple rods 316 to be attached to the body 304 of the phantom 300.

[0036] In the embodiments shown in Figures 3 to 6, the first rod holder 312 and the second rod holder 314 are configured to hold one rod (such as rod 316). In some examples, additionally or alternatively, the first rod holder 312 and the second rod holder 314 can be configured to hold multiple rods. For example, Figure 7 shows an exemplary rod holder 702 coupled to the body 704 of the phantom 700. The rod holder 702 has three openings 706, 708, and 710 and is shown to be connected to three rods: a first rod 714, a second rod 716, and a third rod 718. Each rod 714, 716, and 718 is positioned to pass through one of the openings 706, 708, and 710. A second rod holder identical to the rod holder 702 can also be coupled to the body 704 and the rods 714, 716, and 718. The rod holder 702 may include one or more projections similar to the projection 320 of the first rod holder 312. The body portion 704 may include one or more notches configured to receive one or more projections of the rod holder 702, and may include the same number of notches as the projections. In one example, the rod holder 702 may have only one projection, thereby allowing the body portion 704 to have the same structure as the body portion 304. As a result, the rod holders 312 and 314 shown in Figures 3 to 5 and the rod holder 702 shown in Figure 7 can be interchanged without modifying the phantom body portions 304 and 704.

[0037] The rods held in the rod holders of any embodiment described herein may include iodine materials. The phantom bodies of any embodiment described herein may include non-iodine materials. Phantoms containing both iodine and non-iodine materials can be used for calibrating imaging devices.

[0038] Referring to Figure 8, another exemplary phantom 800 is shown, which includes an exemplary rod holding system 801. The phantom 800 includes a body 802. In some embodiments, the body 802 has a cylindrical shape. The body 802 is hollow and forms an internal volume of the cylinder into which a material can be contained. In one example, this material can be water. In another example, the material of the body 802 can be a non-iodine material.

[0039] An axial system 899 is shown, containing three axes (i.e., the x-axis, the y-axis perpendicular to the x-axis, and the z-axis perpendicular to both the x and y axes). The z-axis is parallel to the longitudinal length of Phantom 800 and the central axis. The xy-plane is parallel to the radial direction of Phantom 800.

[0040] The retaining system 801 may include a first end plate 812 and a second end plate 814 coupled to the main body 802 of the phantom 800. The first end plate 812 and the second end plate 814 may be positioned at opposite ends of the main body 802. The first end plate 812 may have a substantially circular shape. The first end plate 812 can be physically coupled to the main body 802 by a plurality of fasteners 816. In some examples, the first end plate 812 and the second end plate 814 may be integrally formed with the main body 802. The first end plate 812 may further include a projection 818. The projection 81 may be positioned relative to the plurality of fasteners 816 such that the plurality of fasteners 816 are located between the projection 818 and the periphery of the first end plate 812. However, fasteners may be used in other positions. The exemplary projection 818 allows the phantom 800 to be easily attached to the table or table accessory of the imaging device, and to be scanned for calibration of the imaging device. For this purpose, the projection 818 includes a recess 819, in which a component of the table can be placed to attach the phantom 800 to the table or table accessory.

[0041] In some examples, the second end plate 84 may have the same size and shape as the first end plate 812. That is, the second end plate 814 may have the features of the first end plate 812. Thus, the second end plate 814 may include projections 818. The second end plate 814 may further include a plurality of fasteners that physically connect the second end plate 814 to the main body 802. Additionally or alternatively, the second end plate 814 may not include projections, and the phantom 800 may be held only by projections 818.

[0042] The first end plate 812 and the second end plate 814 may further include a plurality of tabs integrally positioned with these plates. The first end plate 812 may include a first tab 822, a second tab 824, and a third tab 826. Each of the tabs 822, 824, and 826 may be identical in shape and size. The first tab 822, 824, and 826 may extend from the periphery of the first end plate 812. In one example, the first tab 822, 824, and 826 may be spaced apart in the lower half of the first end plate 812. In one example, the arc distance between the first tab 822 and the second tab 824 is equal to the arc distance between the second tab 824 and the third tab 826. The arc distance between the first tab 822 and the third tab 826 can be equal to twice the arc distance between the first tab 822 and the second tab 824.

[0043] The second end plate 814 may include a first tab 832 and a second tab 834. The second end plate 814 may further include a third tab, which is hidden by the main body 802 in Figure 8. The first tab 832 is aligned with the first tab 822 on the z-axis. The second tab 834 is aligned with the second tab 824 on the z-axis. The third tab is aligned with the third tab 826 on the z-axis. The arc distance between the first tab 832 and the second tab 834 is equal to the arc distance between the first tab 822 and the second tab 824. The arc distance between the second tab 834 and the third tab (which is hidden in Figure 8, for example) may be equal to the arc distance between the second tab 824 and the third tab 826.

[0044] Each of the multiple tabs on the first end plate 812 and the second end plate 814 may include a corresponding opening. That is, the first end plate 812 includes a first set of openings, and the second end plate 814 includes a second set of openings. The second set of openings corresponds to the first set of openings. The exemplary openings are configured to receive a rod. In the illustrated example, each end plate of the first end plate 812 and the second end plate 814 includes three tabs and corresponding openings, but the number of tabs and corresponding openings can be any number. For example, the first tab 822 of the first end plate 812 may include a first opening 823. The second tab 824 of the first end plate 812 may include a second opening 825. The third tab 826 of the first end plate 812 may include a third opening 827. The first tab 832 of the second end plate 814 may include a first opening 833. The second tab 834 of the second end plate 814 may include a second opening 835. The third tab of the second end plate 814 may include a third opening (not shown). The first opening 823 aligns with the first opening 833. A rod extends from the first opening 823 to the first opening 833, and the first tabs 822 and 832 can hold the rod so that it is adjacent to the phantom 800. Similarly, the second opening 825 aligns with the second opening 835, and an additional rod extends from the second opening 825 to the second opening 835, and the second tabs 824 and 834 can hold the other rod together with the phantom 800. Similarly, a third rod may extend from the third opening 827 of the first end plate 812 to the third opening of the second end plate 814.

[0045] The projection 818 is positioned on the midline of the first end plate 812 in the region of the first end plate 812. In one example, the midline bisects the first tab 822 and the third tab 826. Therefore, the projection 818 is closer to the outer periphery of the first end plate 812 than the second tab 824.

[0046] Figure 9 shows an alternative exemplary embodiment of the phantom 900, including a rod holding system 901 used with the exemplary phantom body and rods described herein. An axial system 999 is shown, including three axes (i.e., an x-axis, a y-axis perpendicular to the x-axis, and a z-axis perpendicular to each of the x and y axes). The z-axis may be parallel to the longitudinal axis of the phantom 900. The xy-plane may be parallel to the radial direction of the body. The axial system 999 is also shown in Figures 12–26.

[0047] The illustrated phantom 900 is coupled to a first rod holder 910 and a second rod holder 911 of the rod holding system. The first rod holder 910 and the second rod holder 911 can be similar in shape and size to each other. In the illustrated example, the first rod holder 910 and the second rod holder 911 are substantially annular and coupled to opposite ends of the exemplary phantom body 902. The first rod holder 910 and the second rod holder 911 may include one or more loops 1002 and openings 1004, as detailed in Figures 10 and 11. Referring to Figures 10 and 11, a partial view of a portion of the rod holding system 901 according to one embodiment is shown. The partial view shows a loop 1002 including an opening or slot 1004. The loop 1002 may be coupled to the first rod holder and / or the second rod holder, or it may be integrally formed as part of the first rod holder and / or the second rod holder. In one example, the first and second rod holders have peripheries based on the periphery of the phantom body 902, as shown in Figures 9 and 12-15. A strap or other element can be passed through an opening or slot in the loop 1002 and wrapped around the first or second rod holder. The strap can be tightened onto the rod holder, securing the rod holder to the phantom. In this way, the rod holder can be secured to the phantom via the strap. The loop 1002 includes a first arm 1012, a second arm 1014, and a bridge 1016. The opening 1004 can be defined by each of the first arm 1012, the second arm 1014, and the bridge 1016. In one example, the first arm 1012 and the second arm 1014 are substantially identical in shape and size to each other. The first arm 1012 and the second arm 1014 may have a rectangular cross-sectional shape. The bridge 1016 may extend from the first arm 1012 to the second arm 1014.

[0048] In one example, the strap may include an adhesive. Additionally or alternatively, the strap may include interlocking material, hook-and-loop elements, webbing, or other fastening systems for securing the strap to the Phantom. In such an example, the first end of the strap is secured to the rod holder, and the second end of the strap is passed through a loop and folded back, thereby connecting the first end of the strap to the second end of the strap (e.g., via a hook-and-loop fastener) and securing the rod holder to the Phantom body.

[0049] In some examples, the rod holding system 901 may include a ratchet system, a dial system, or other mechanical system to allow the rod holder to be tightened against the outer surface of the phantom. Some additional examples of this are further described herein. Additionally or alternatively, the rod holding system 901 may include holes and projections that engage with the holes to secure the rod holder to the phantom.

[0050] The first rod holder and the second rod holder may further include at least one lip 1008 so as to allow the first rod holder and the second rod holder to be aligned in the phantom body. The lip 1008 is described in detail below.

[0051] The first rod holder 910 and the exemplary holder may include a plurality of projections extending radially from the periphery of the rod holder, the plurality of projections forming an opening in the exemplary first rod holder. For example, each rod holder may include a first projection 912, a second projection 914, and a third projection 916. The first projection 912, the second projection 914, and the fourth projection 916 are similar in size and shape to one another. The first projection 912, the second projection 914, and the third projection 916 are substantially circular in shape. Alternatively, other shapes corresponding to the shape of the rod may be suitable. The arc distance between the first projection 912 and the second projection 914 is equal to the arc distance between the second projection 914 and the third projection 916. The arc distance between the first projection 912 and the third projection 916 is approximately twice the arc distance between the first projection 912 and the second projection 914. The arc distance between the first projection 912 and the first end of the rod holder adjacent to the loop containing the slot is similar to the arc distance between the third projection 916 and the second end of the rod holder opposite the loop. A gap 918 can be provided between the first end of the rod holder where the loop 1002 is located and the second end of the rod holder. The size of the gap 918 can be adjusted based on the tension of the strap or other fastening system coupled to the rod holder. For this reason, the rod holder has an imperfect ring shape and is not a perfect circle.

[0052] The second rod holder 911 includes a plurality of projections extending radially from the periphery of the rod holder, which may include a plurality of projections forming an opening in the exemplary second rod holder, and the plurality of projections of the second rod holder 911 may be similar to the plurality of projections described with respect to the first rod holder (the first rod holder shown in Figures 12, 13, and 15). Thus, the exemplary first rod holder forms a first set of openings, and the second rod holder forms a second set of openings. The first rod holder and the second rod holder are positioned on the body of the phantom such that the first set of openings and the second set of openings are aligned.

[0053] In one example, the first projection 912 of the first rod holder 910 is aligned with the first projection 920 of the second rod holder 940 in the z-axis. The second projection 914 of the first rod holder 910 is aligned with the second projection 1202 of the second rod holder 911 (shown in Figures 12-15) in the z-axis. The third projection 916 of the first rod holder 910 is aligned with the third projection 922 of the second rod holder 911.

[0054] The first rod 924 can extend from the first projection 912 of the first rod holder 910 to the first projection 920 of the second rod holder 911. The second rod 926 can extend from the second projection 914 of the first rod holder 910 to the second projection 1202 of the second rod holder 911. The third rod 928 can extend from the third projection 916 of the first rod holder 910 to the third projection 922 of the second rod holder 911. The first rod 924, the second rod 926, and the third rod 928 can be substantially identical in size and shape. In one example, each of the rods, the first rod 924, the second rod 926, and the third rod 928, is cylindrical and has a similar material density. In one example, the first rod 924, the second rod 926, and the third rod 928 each contain iodine. In some examples, additionally or alternatively, one or more of the first rod 924, the second rod 926, and the third rod 928 may contain a different iodine concentration than that contained in the other rods. The rods can be interchangeable. The rods can be interchangeable with rods of different sizes and / or different iodine concentrations. In some examples, rods of different shapes may be used with the exemplary rod holders and rod retaining systems described herein. In such examples, the openings are formed to correspond to the shape of the rods.

[0055] The first rod 924, the second rod 926, and the third rod 928 are parallel to each other and can be parallel to the z-axis and the longitudinal direction of the phantom 900. As shown in Figures 12 and 13, the first rod 924, the second rod 926, and the third rod 928 do not extend beyond the outlines of the first projection 920, the second projection 1202, and the third projection 922 of the second rod holder 911 in the z-axis direction. Figures 12 and 13 further show the first rod 924, the second rod 926, and the third rod 928 extending beyond the outlines of the first projection 912, the second projection 914, and the third projection 916 of the first rod holder 910. The extensions of the first rod 924, the second rod 926, and the third rod 928 may extend beyond the overall outline of the first rod holder 910, including the lip 1008. The lip 1008 can contact the end plate of the phantom. The lip 1008 facilitates alignment, allowing the rod holding system 901 to be positioned at a desired location on the phantom.

[0056] The first rod 924, the second rod 926, and the third rod 928 may be made of different materials than the main body 902. For example, the main body 902 may be made of a non-iodine material, while the first rod 924, the second rod 926, and the third rod 928 may be made of an iodine material. The iodine concentrations of each of the first rod 924, the second rod 926, and the third rod 928 may be the same or different, depending on the required calibration process. The first rod 924, the second rod 926, and the third rod 928 may be in surface contact with the main body 902, or they may be separated from the main body 902.

[0057] Figure 14 shows a front view of the first end plate 904 of the Phantom 900. The lip 1008 of the first rod holder may have a similar depth or thickness along each arc between the respective projections 912, 914, and 916 arranged along the periphery of the first rod holder, as shown in Figure 14. The front view further shows how the lip of the first rod holder 910 includes a first portion 1402, a second portion 1404, a third portion 1406, and a fourth portion 1408. In one example, each portion of the first portion 1402, the second portion 1404, the third portion 1406, and the fourth portion 1408 has a similar shape and size. Each portion of the first portion 1402, the second portion 1404, the third portion 1406, and the fourth portion 1408 may have an arc shape. The first portion 1402, the second portion 1404, the third portion 1406, and the fourth portion 1408 can be positioned in separate quadrants of the first rod holder 910. The first portion 1402 can extend from the first end where the loop 1002 is positioned to the first projection 912. The second portion 1404 can extend from the first projection 912 to the second projection 914. The third portion 1406 can extend from the second projection 914 to the third projection 916. The fourth portion 1408 can extend from the third projection 916 to the second end 1410 of the first rod holder 910.

[0058] The first portion 1402, the second portion 1404, the third portion 1406, and the fourth portion 1408 of the lip 1008 can make surface contact with the first end plate 904. The first portion 1402, the second portion 1404, the third portion 1406, and the fourth portion 1408 can prevent the first rod holder 910 from being positioned in the middle portion of the phantom body 902. Additionally or alternatively, the first portion 1402, the second portion 1404, the third portion 1406, and the fourth portion 1408 can easily position the first rod holder 910 in a desired position.

[0059] Figure 15 shows a front view of the second end plate 906 of the Phantom 900. The second end plate 906 can be positioned on the end of the main body 902 of the Phantom 900 opposite to the first end plate 904. The front view further shows how the lip 1008 of the second rod holder 911 includes a first portion 1502, a second portion 1504, a third portion 1506, and a fourth portion 1508. The first portion 1502, the second portion 1504, the third portion 1506, and the fourth portion 1508 of the lip can be positioned in separate quadrants of the second rod holder 911. For example, the lip 908 of the second rod holder shown in Figure 15 may include an additional cutout to allow it to receive the projection 1510 of the Phantom.

[0060] The first portion 1502, the second portion 1504, the third portion 1506, and the fourth portion 1508 can make surface contact with the second end plate 906. The first portion 1502, the second portion 1504, the third portion 1506, and the fourth portion 1508 prevent the second rod holder 911 from being positioned in the middle portion of the phantom body 902. Additionally or alternatively, the first portion 1502, the second portion 1504, the third portion 1506, and the fourth portion 1508 can be used to position the second rod holder 911 in a desired position.

[0061] The first portion 1502 and the fourth portion 1508 can be formed in the same manner as each other. The second portion 1504 and the third portion 1506 can be formed in the same manner as each other, and furthermore, the second portion 1504 and the third portion 1506 can be formed differently from the first portion 1502 and the fourth portion 1508. The first portion 1502 and the fourth portion 1508 can be formed in a shape complementary to the projection 1510 and the plurality of fasteners 1512. In one example, the first portion 1502 and the fourth portion 1508 may include a first notch. The first notch may be curved to correspond to the curvature of the plurality of fasteners 1512. The first portion 1502 and the fourth portion 1508 may further include a second notch. The second notch may include a straight edge corresponding to the shape of the projection 1510. As a result, the second notch can conform to the shape of the projection 1510 without coming into contact with it.

[0062] Figure 16 shows a perspective view of the rod holding system 1600 for the Phantom. The rod holding system 1600 can be coupled to a main body similar to the main body 1102 described above with reference to Figures 11-15. In the example of Figure 16, the rod holding system 1600 includes a first rod holder 1602, a second rod holder 1604, and a plurality of rods 1606. The first rod holder 1602 and the second rod holder 1604 include a plurality of projections 1608 having an opening 1610. In the example shown in Figure 16, each rod of the plurality of rods can be configured to be press-fitted into the opening of the projection. Similar to the Phantom 900, in the example shown in Figure 16, the first rod holding section 1602 and the second rod holding section 1604 are configured to be fixed to the main body of the Phantom via a loop-strap mechanism 1612. However, in other examples, other fastening mechanisms may be suitable.

[0063] Figure 17 shows a perspective view of a rod holding system 1700 for a phantom. The rod holding system 1700 can be coupled to a body similar to the body 902 described above, for example, with reference to Figures 11-15. In the example of Figure 17, the rod holding system 1700 includes a first rod holder 1702 and a plurality of rods 1704. The first rod holder 1702 and the other rod holder examples shown in Figures 17-24 are examples of rod holding systems configured to hold at least one rod 1704 on the outer surface of the phantom's body. The first rod holder 1704 includes a plurality of projections 1706, including an opening 1708. In some examples, at least one projection 1706 includes an alignment portion 1710 (e.g., a laser alignment line), which is used in conjunction with a laser alignment tool of an imaging device to align the phantom in a bore or on a table. Furthermore, each projection 1706 includes a detent 1712 corresponding to a groove 1714 of at least one rod. In the figure, one of several rods 1704 containing grooves 1714 is shown with a dashed line to make the detent 1712 visible. The detent 1712 and groove 1714 secure at least one rod 1704 in place within the rod holder 1702. In some examples, the detent 1712 is a spring-loaded button that retracts under pressure and connects to a radial groove 1714 located near the end of each rod 1704. An example of a spring-loaded button is schematically shown as a circle on the inner surface of the opening 1708. Another example of a rod 1704 having a radial groove 1714 is shown in Figure 25. In one example, each of the multiple rods 1704 can be slid longitudinally into the opening 1708 of one of the multiple projections 1706 of the rod holder 1702. When the rod slides into the opening 1708 of the projection 1706, the rod 1704 pushes down the spring-loaded button 17112 until the button and radial groove 1714 are aligned. Once the button and radial groove 1714 are aligned, the pressure is released and the button enters the radial groove. In this way, the rod 1704 is held in the clamp.In some examples, one end of the rod 1704 may include a tapered portion to allow the detent 1712 to be easily pushed down when the rod 1704 is inserted into the opening 1708 of the projection 1706. Furthermore, the first rod holder 1702 includes a fastener 1716 or retainer configured to adjustably hold the first rod holder to the main body. In the illustrated example, the fastener or retainer 1716 may be a screw with a locking lever 1718. That is, the lever 1718 can be rotated manually (e.g., by a technician) to tighten the rod holder 1702 to the periphery of the main body. Then, by moving the lever 1718 to a locked position (e.g., perpendicular to the screw), the screw is prevented from moving further, the fastener is firmly secured, and as a result, the rod holder can be firmly fixed in place. In other examples, screws, nuts, clamps, wing nuts, or other fastening mechanisms may be suitable.

[0064] Figure 18 shows a perspective view of a rod holding system 1800 for a phantom. The rod holding system 1800 can be coupled to a main body similar to the main body 902 described above with reference to Figures 11 to 15. In the example of Figure 18, the rod holding system 1800 includes a first rod holder 1802 and a plurality of rods 1804. The first rod holder 1802 includes a plurality of projections 1806, which can be configured similarly to the plurality of projections described with reference to Figure 17, and each rod of the plurality of rods 1804 can be pushed into the opening 1808 of the projection 1806 by squeeze compression. In some examples, at least one projection 1801 may include a laser alignment line 1810, which can be used with a laser alignment tool to align the phantom. Similar to the rod holding system 1700 shown in Figure 17, the first rod holder 1802 is configured to be adjustablely held in place by a fastener or clamp 1812. However, in other examples, other clamping mechanisms may be more suitable.

[0065] Figure 19 shows a perspective view of a rod holding system 1900 for a Phantom. The rod holding system 1900 can be coupled to a main body similar to the main body 902 described above with reference to Figures 11-15. In the example of Figure 19, the rod holding system 1900 includes a first rod holder 1902, a second rod holder 1904, and a plurality of rods 1906. Each of the plurality of rods 1906 has at least one rod clip 1908, the rod clip 1908 being integrally formed with the rod 1906. Alternatively, the rod clip 1908 can be detachably coupled to the rod 1906 by means of, for example, a press-fit connection, adhesive, magnet, etc. The rod clip 1908 is configured to be detachably attached to the rod holders 1902 and 1904 (e.g., by clipping and unclipping). The exemplary rod clip 1908 is configured to fit into the openings 1910 of the first rod holder 1902 and the second rod holder 1904. For example, the rod clip 1908 may include a projection 1912 (shown in Figure 26) that engages with a slot or aperture 1914 located in the rod holders 1902 and 1904. In some examples, the projection 1912 is formed (e.g., has a different shape) so that the rod 1906 can only be mounted in a specific orientation. In the example in Figure 19, each rod 1906 includes a first rod clip 1908a and a second rod clip 1908b, which are located at the ends of the rod 1906. An example of a rod 1906 equipped with the first rod clip 1908a and the second rod clip 1908b is shown in Figure 26. In other examples, the rod clips may be magnetically attached to the rod holders. Similar to the Phantom 900, in the example shown in Figure 9, the first rod holder 1902 and the second rod holder 1904 are configured to be secured to the main body via a loop-strap mechanism. However, in other examples, other fastening mechanisms may be more suitable.

[0066] Figure 20 shows a perspective view of the rod holding system 2000 for the Phantom. The rod holding system 2000 can be coupled to a main body similar to the main body 902 described above with reference to Figures 11 to 15. In the example of Figure 20, the rod holding system 2000 includes a first rod holder 2002 and a plurality of rods 2004. Similar to the example of Figure 19, each of the plurality of rods 2004 includes a rod clip 2006, the rod clip 2006 being integrally formed with the rod 2004 or otherwise coupled to the rod 2004. The rod clip 2006 is configured to be detachably attached to the rod holder 2002 (e.g., by clipping and unclipping) via a projection 1912 on the rod 2004 (shown in Figure 26) and an aperture 2008 adjacent to the opening 2010 of the rod holder 2002, similar to those described in reference to Figure 19. Similar to the rod holding system 1700 in the example shown in Figure 17, the first rod holder 2002 is configured to be adjustablely held in the main body via a fastener or clamp 2012. However, in other examples, other fastening mechanisms may be suitable.

[0067] Figure 21 shows a perspective view of the rod holding system 2100 for the Phantom. The rod holding system 2100 can be coupled to a main body similar to the main body 902 described above with reference to Figures 11-15. In the example of Figure 21, the rod holding system 2100 includes a first rod holder 2102, a second rod holder 2104, and a plurality of rods 2106. Each holder of the first rod holder 2102 and the second rod holder 2104 includes a hinge 2108, which is configured to rotate about a hinge axis parallel to the longitudinal direction or central axis of the rod holding system 2100. In the example of Figure 21, the hinge 2108 is an external hinge located on the outside of the rod holders 2102 and 2104. For example, the first rod holder 2102 and the second rod holder 2104 can be opened, for example, like a clamshell, by rotating them around the hinge 2108, and the multiple rods 2106, which are arranged on multiple projections similar to the clamp described with reference to Figures 11 to 15, can be press-fitted or secured with rod clips (for example, the rod clip described in Figure 19). With the rods 2106 in place, the rod holders 2102 and 2104 can be closed around the main body of the phantom (such as the main body 902). Similar to the phantom 900, in the example shown in Figure 21, the first rod holder 2102 and the second rod holder 2104 are configured to be secured to the main body via a loop-strap mechanism. However, in other examples, other fastening mechanisms may be suitable.

[0068] Figure 22 shows a perspective view of the rod holding system 2200 for the Phantom. The rod holding system 2200 can be coupled to a main body similar to the main body 902 described above with reference to Figures 11 to 15. In the example of Figure 22, the rod holding system 2200 includes a first rod holder 2202 and a plurality of rods 2204. The first rod holder 2202 includes a hinge 2206 (e.g., an external hinge) similar to the hinge 2108 described with reference to Figure 21. Similar to the rod holding system 1600, in the example shown in Figure 22, the first rod holder 2202 is configured to be adjustablely held to the main body via a fastener or crimp 2208. However, in other examples, other fastening mechanisms may be suitable.

[0069] Figure 23 shows a perspective view of the rod holding system 2300 for the Phantom. The rod holding system 2300 can be coupled to a main body similar to the main body 902 described above with reference to Figures 11-15. In the example of Figure 23, the rod holding system 2300 includes a first rod holder 2302, a second rod holder 2304, and several rods 2306. Each holder of the first rod holder 2302 and the second rod holder 2304 includes a hinge 2308 that functions similarly to the hinges 2108 and 2206 described with reference to Figures 21-22. However, in the example of Figure 23, the hinge 2308 is an internal hinge. In the example shown in Figure 23, similar to the Phantom 900, the first rod holder 2302 and the second rod holder 2304 are configured to be secured to the main body via a loop-strap mechanism. However, in other examples, other fastening mechanisms may be suitable.

[0070] Figure 24 shows a perspective view of the rod holding system 2400 for the Phantom. The rod holding system 2400 can be coupled to a main body similar to the main body 902 described above with reference to Figures 11-15. In the example of Figure 24, the rod holding system 2400 includes a first rod holder 2402 and several rods 2404. The first rod holder 2402 includes a hinge 2406 (e.g., an internal hinge) similar to the hinge 2308 described with reference to Figure 23. In the example shown in Figure 24, similar to the rod holding system 1600, the first rod holder 2402 is configured to be adjustablely held to the main body via a fastener or crimp 2408. However, in other examples, other fastening mechanisms may be suitable. Various types of hinges are shown in Figures 22-24, but it should be understood that the position of the hinges may differ. For example, in Figure 22, the hinge is located on the opposite side of the fastener or clasp (e.g., 180 degrees away from the fastener). Alternatively, the hinge may be located at a different position on the periphery of the rod holder. For example, Figure 23 shows an exemplary hinge located next to the second projection of the rod holder, where the hinge is on the opposite side of the fastener or clasp. Other positions for the hinge may also be suitable.

[0071] Figures 25 and 26 show examples of rods (such as iodine-containing rods). Referring first to Figure 25, a rod 1704 is shown. Rod 1704 is an example of a rod 1704 having a radial groove 1714. A rod 1704 including the radial groove 1714 can be configured to slide onto a projection of a rod holder including a corresponding spring-loaded button, as described in Figure 17. Figure 26 shows a rod 1906. Rod 1906 is an example of a rod having at least one rod clip 1908, the rod clip 1908 being integrally formed with the rod 1906. In this example, the rod 1906 includes a first rod clip 1908a located at the first end and a second rod clip 1908b located at the opposite second end. The rod clip 1908 is configured to be detachably attached to a rod holder (for example, by clipping and unclipping, as described with reference to Figures 19-20). As illustrated, the rod clip 1908 may include a projection 1912 or other projection that engages with a corresponding slot or aperture of the rod holder.

[0072] Thus, the rod holding system configured to hold the iodine-containing rod includes at least a first rod holder. The first rod holder (in some examples, a first rod holder and a second rod holder, or a first rod holder and multiple rod holders) can engage with a feature portion of the phantom's body. Additionally or alternatively, the first and second rod holders are integrally positioned on the first and second end plates of the phantom. Additionally or alternatively, at least the first rod holder (in some examples, the first and second rod holders) may be fixed to the outer surface of the phantom or physically bonded to the outer surface of the phantom without engaging with a feature portion of the phantom. This allows the first rod holder (and, if a second rod holder is included, the first and second rod holders) to be retrofitted to an existing phantom without altering the phantom design.

[0073] At least the first rod holder may include a flexible material and / or a rigid material. In one example, a rod holder (or multiple rod holders) may accept one or more rods from a plurality of iodine-containing rods before being coupled to the phantom. Additionally or alternatively, at least one rod holder may be coupled to the phantom before accepting one or more rods from a plurality of iodine-containing rods. Each rod of the plurality of iodine-containing rods may slide through a corresponding eyelet of at least the first rod holder.

[0074] At least one rod holder may include an eyelet and / or opening for receiving an iodine-containing rod. The eyelet may extend away from the body. This allows the rod to be positioned radially outward relative to the outer surface of the body. In some examples, a gap may be provided between the outer surface of the body and the multiple iodine-containing rods so that the iodine-containing rods do not physically contact the body. In other embodiments, the gap may be eliminated, either additionally or alternatively, allowing the multiple rods to physically contact the body.

[0075] In some examples, the main body can be a basic cylinder, and the rods can be smaller cylinders arranged around the main body. The spacing between the rods can be constant. In some embodiments, the rods can be held within the same quadrant of the phantom. In other embodiments, the rods can be held within the same semicircle of the phantom. In some applications, one or more eyelets of the rod holders may not be used, and the rods may be held by only some of the eyelets, and not by all of them. If multiple iodine-containing rods are not needed, the rod holders can be separated from the phantom. Separation may, in some examples, include sliding at least the first rod holder, unfastening at least the first rod holder, or unfastening at least the first rod holder's strap.

[0076] This disclosure also provides support for a retention system for a phantom for calibrating an imaging system. The retention system includes at least one rod holder, the at least one rod holder including at least one opening configured to secure at least one rod of the phantom to the retention system, and a fastener configured to secure the at least one rod holder to the body of the phantom. In a first embodiment of the system, the at least one rod holder includes a plate coupled to the end of the body of the phantom, the at least one opening being integrally formed with the plate. In a second embodiment of the system, optionally including the first embodiment, the at least one rod holder includes a ring, the ring configured to be coupled to the outer surface of the body of the phantom. In a third embodiment of the system, optionally including one or both embodiments of the first and second embodiments, the fastener of the at least one rod holder includes a detent that engages with a groove in the body of the phantom. In a fourth embodiment of a system comprising one or more embodiments from the first to third embodiments or any selection of each embodiment, the fastener of the at least one rod holder includes a screw. In a fifth embodiment of a system comprising one or more embodiments from the first to fourth embodiments or any selection of each embodiment, the screw includes a locking lever for tightening and locking the screw. In a sixth embodiment of a system comprising one or more embodiments from the first to fifth embodiments or any selection of each embodiment, the fastener includes a slot configured to receive a strap for securing the at least one rod holder to the outer surface of the main body. In a seventh embodiment of a system comprising one or more embodiments from the first to sixth embodiments or any selection of each embodiment, the at least one rod holder includes at least one aperture for receiving at least one detent of a clip coupled to a rod, the clip enabling the rod to be detachably coupled to the at least one rod holder.In an eighth embodiment of a system comprising one or more embodiments from the first to seventh embodiments, or any selection of each embodiment, the at least one rod holder includes a hinge. In a ninth embodiment of a system comprising one or more embodiments from the first to eighth embodiments, or any selection of each embodiment, the at least one rod holder includes at least one detent corresponding to a groove for the at least one rod, the at least one detent and the at least one groove securing the at least one rod in a predetermined position within the rod holder.

[0077] This disclosure also supports phantoms for imaging systems. A phantom for an imaging system includes a body, one or more rods, and a rod holding system coupled to the outer surface of the body of the phantom, wherein the rod holding system includes a plurality of openings, each opening of the plurality of openings configured to receive one of the plurality of rods, and each opening of the plurality of openings includes a central axis parallel to the longitudinal axis of the body. In a first embodiment of the system, the one or more rods include an iodine material, and the body includes a non-iodine fluid. In a second embodiment of the system, which optionally includes an embodiment of the first embodiment, the rod holding system includes fasteners for coupling the rod holding system to the body. In a third embodiment of the system, which optionally includes one or both embodiments of the first and second embodiments, the plurality of openings of the rod holding system include a first set of openings and a second set of openings positioned close to the opposite end of the body, with each opening of the first set of openings aligning with one opening of the second set of openings. In a fourth embodiment of a system comprising one or more embodiments from the first to third embodiments, or any selection of each embodiment, each of the one or more rods includes a first end that passes through one of the first set of openings and a second end that passes through a corresponding opening in the second set of openings.

[0078] This disclosure also provides support for a rod retention system for a phantom for calibrating an imaging system. The rod retention system includes at least one rod holder configured to be detachably coupled to the phantom body, and at least one rod configured to be detachably coupled to the at least one rod holder, the rod including an integrated locking mechanism. In a first embodiment of the system, the at least one rod holder includes at least one aperture, and the integrated locking mechanism includes at least one detent that enters into the at least one aperture to couple the at least one rod to the rod holder. In a second embodiment of the system, which optionally includes the first embodiment, the at least one detent is located on a clip of the at least one rod. In a third embodiment of the system, which optionally includes one or both embodiments of the first and second embodiments, the at least one rod holder includes at least one detent corresponding to a groove of the at least one rod, and the at least one detent and at least one groove secure the at least one rod in a predetermined position within the rod holder. In a fourth embodiment of a system comprising one or more embodiments from the first to third embodiments, or any selection of each embodiment, the at least one rod holder includes at least one alignment portion.

[0079] Figures 1-26 show examples of configurations of the relative positions of various components. If these elements are shown as being in direct contact with or directly connected to one another, then in at least one example, these elements can be said to be in direct contact or directly connected, respectively. Similarly, if elements are shown as being continuous or adjacent to one another, then in at least one example, they can be said to be continuous or adjacent to one another. For example, components that are in surface contact with one another can be called components in surface contact. For another example, elements that are spaced apart from each other, with only space between them and no other components present, can be said to be such in at least one example. For yet another example, elements shown above and below each other, on opposite sides of each other, or to the left and right of each other can be said to be such relative to one another. Furthermore, as shown in the figures, in at least one example, the highest element or a point on that element can be called the "top" of the component, and the lowest element or a point on that element can be called the "bottom" of the component. In this specification, “upper / lower,” “top / bottom,” and “above / below” are relative to the vertical axis of the figure and can be used to describe the relative positional relationships of the elements in the figure. For example, if one element is shown above another, that element is, as one example, positioned vertically directly above the other element. As yet another example, the shape of an element shown in the figure can be said to have that shape (e.g., circular, straight, planar, curved, rounded, chamfered, angled, etc.). Furthermore, if in at least one example elements are shown intersecting each other, they can be said to be intersecting elements or intersecting each other. Furthermore, if in one example an element is shown within or outside of another element, it can be said to be such an element. Note that one or more components referred to as “substantially similar and / or identical” differ from each other by manufacturing tolerances (e.g., within a 1% to 5% deviation). Figures 3 to 26 are shown at a generally constant scale, but other dimensions may be used as needed.

[0080] Where the elements of various embodiments of this disclosure are introduced, the articles “a,” “an,” and “the” are intended to mean that there is one or more of those elements. Terms such as “first,” “second,” etc., are used to distinguish one element from another, and do not indicate order, quantity, or importance. “comprising, including, having” are intended to be comprehensive and mean that there may be additional elements other than those listed. Where terms such as “connected” and “joined” are used herein, one object (e.g., material, element, structure, member, etc.) may be connected to or joined to another object, whether one object is directly connected to or joined to another object, or whether there is one or more intervening objects between one object and another object. In addition, it should be understood that reference to “one embodiment” or “a certain embodiment” in this disclosure is not intended to be construed as excluding the existence of additional embodiments that similarly incorporate the referred features.

[0081] In addition to the modifications described herein, a person skilled in the art can consider many other modifications and alternative structures without departing from the spirit and scope of this description, and the claims are intended to include such modifications and structures. Therefore, although the above information is described in particular detail with respect to what is currently considered the most practical and preferred embodiment, it will be clear to a person skilled in the art that many modifications are possible in form, function, method of operation and use (but not limited to these) without departing from the principles and concepts described herein. Furthermore, examples and embodiments described herein are meant in all respects to be merely illustrative and should not be construed restrictively in any way. [Explanation of Symbols]

[0082] 81:Protrusion 84: Second end plate 100: PCCT System 102: Gantry 104 :X-ray source 106: X-ray emission beam 108: Detector array 110: Image processor unit 112: Subject 114: Table 200: Imaging System 202: Detector element 204: Subject 206: Center of rotation 208: Control mechanism 210: X-ray controller 212: Gantry Motor Controller 213: Slip ring 216: Computing device 218 :Mass storage device 220: Operator Console 226: Table Motor Controller 230: Image Reconstructor 232:Display device 300: Phantom 301: Rod holding system

Claims

1. A phantom holding system for calibrating an imaging system, wherein the holding system is It includes at least one rod holder, and the at least one rod holder is At least one opening configured to secure at least one rod of the phantom to the holding system, and A fastener configured to secure at least one rod holder to the main body of the phantom. A holding system including

2. The holding system according to claim 1, wherein the at least one rod holder includes a plate coupled to the end of the main body of the phantom, and the at least one opening is integrally formed with the plate.

3. The retaining system according to claim 1, wherein the at least one rod holder includes a ring, the ring being configured to be coupled to the outer surface of the main body of the phantom.

4. The retaining system according to claim 1, wherein the fastener of at least one rod holder includes a detent that engages with a groove in the main body of the phantom.

5. The retaining system according to claim 1, wherein the fastener of at least one rod holder includes a screw.

6. The retaining system according to claim 5, wherein the screw includes a locking lever for tightening and locking the screw.

7. The retaining system according to claim 1, wherein the fastener includes a slot configured to receive a strap for securing the at least one rod holder to the outer surface of the main body.

8. The retaining system according to claim 1, wherein the at least one rod holder includes at least one aperture for receiving at least one detent of a clip coupled to a rod, the clip enabling the rod to be detachably coupled to the at least one rod holder.

9. The holding system according to claim 1, wherein the at least one rod holder includes a hinge.

10. The holding system according to claim 1, wherein the at least one rod holder includes at least one detent corresponding to a groove of the at least one rod, and the at least one detent and the at least one groove fix the at least one rod in a predetermined position within the rod holder.

11. A phantom for imaging systems, Main body, One or more rods, and A rod holding system coupled to the outer surface of the main body of the phantom, wherein the rod holding system includes a plurality of openings, each of the plurality of openings is configured to receive one of the plurality of rods, and each of the plurality of openings includes a central axis parallel to the longitudinal axis of the main body. Phantom, including

12. The phantom according to claim 11, wherein one or more of the rods contain an iodine material, and the main body contains a non-iodine fluid.

13. The phantom according to claim 11, wherein the rod holding system includes fasteners for connecting the rod holding system and the main body.

14. The phantom according to claim 11, wherein the plurality of openings in the rod holding system include a first set of openings and a second set of openings arranged in proximity to the opposite end of the main body, and each opening in the first set of openings aligns with one of the openings in the second set of openings.

15. The phantom according to claim 14, wherein each of the one or more rods includes a first end that passes through one of the openings of the first set of openings and a second end that passes through a corresponding opening of the second set of openings.

16. A rod holding system for a phantom for calibrating an imaging system, wherein the rod holding system is At least one rod holder configured to be detachably attached to the Phantom body, and At least one rod configured to be detachably coupled to the at least one rod holder, the at least one rod including an integrated locking mechanism A rod holding system, including a rod holding system.

17. The rod holding system according to claim 16, wherein the at least one rod holder includes at least one aperture, and the integrated locking mechanism includes at least one detent that enters into the at least one aperture to connect the at least one rod to the rod holder.

18. The rod holding system according to claim 17, wherein the at least one detent is located on a clip of the at least one rod.

19. The rod holding system according to claim 16, wherein the at least one rod holder includes at least one detent corresponding to a groove of the at least one rod, and the at least one detent and the at least one groove secure the at least one rod in a predetermined position within the rod holder.

20. The phantom according to claim 16, wherein the at least one rod holder includes at least one alignment portion.

Images