Front collimator with built-in alignment mechanism

Abstract

This invention provides a precollimator for a CT imaging system. The precollimator includes a collimator housing comprising a plurality of walls, wherein the plurality of walls includes a first wall and second and third walls laterally connected to the first wall, the first wall being configured to face an X-ray source when the precollimator is coupled to the CT imaging system. The precollimator also includes a bowtie filter assembly disposed within the collimator housing and including a bowtie filter. The precollimator further includes an adjustment mechanism configured to laterally move the bowtie filter assembly within the collimator housing between the second and third walls.

Description

Background Technology

[0001] The subject matter disclosed in this article relates to medical imaging systems, and more specifically to precollimators with additively manufactured components.

[0002] In computed tomography (CT), X-ray radiation crosses the subject of interest (such as a human patient), and a portion of the radiation impacts the detectors that collect image data. In digital X-ray systems, photodetectors generate signals representing the amount or intensity of radiation impacting discrete pixel areas on the detector surface. These signals can then be processed to generate images that can be displayed for viewing. From images produced by such systems, it is possible to identify and examine internal structures and organs within the patient's body. In CT systems, as the gantry moves around the patient, a detector array (comprising a series of detector elements or sensors) generates similar signals at various locations, allowing for volumetric reconstruction.

[0003] CT imaging systems may include a precollimator to ensure that the subject of interest receives the expected dose. The collimator blades of the precollimator are adjusted in front of the X-ray source to create the appropriate opening or aperture to deliver the X-rays used for scanning, as set by the operator. Adjustment of the precollimator is critical for obtaining a precisely shaped X-ray beam to achieve high-quality images of the patient. Typically, during system alignment, the X-ray filter (e.g., a bowtie filter) must be adjusted to center it against the X-ray beam. This involves either moving the entire collimator (which is often very heavy) or moving the X-ray filter by removing multiple components of the collimator (e.g., the cover). In some cases, the X-ray filter needs to be removed during system alignment (e.g., during air scanning). This makes the process cumbersome and time-consuming. Summary of the Invention

[0004] The following outlines some embodiments commensurate with the scope of the originally claimed subject matter. These embodiments are not intended to limit the scope of the claimed subject matter, but rather to provide only a brief overview of the possible forms of the subject matter. In reality, the subject matter may include many forms that may be similar to or different from the embodiments described below.

[0005] In one embodiment, a precollimator for a CT imaging system is provided. The precollimator includes a collimator housing comprising a plurality of walls, including a first wall and second and third walls laterally connected to the first wall. The first wall is configured to face an X-ray source when the collimator is coupled to the CT imaging system. The precollimator also includes a bowtie filter assembly disposed within the collimator housing and including a bowtie filter. The precollimator further includes an adjustment mechanism configured to laterally move the bowtie filter assembly within the collimator housing between the second and third walls.

[0006] In another embodiment, a precollimator for a CT imaging system is provided. The precollimator includes a collimator housing. The precollimator also includes a bowtie filter assembly disposed within the collimator housing and including a bowtie filter. The precollimator further includes an adjustment mechanism configured to move the bowtie filter assembly within the collimator housing along a first direction and a second direction, wherein movement of the bowtie filter assembly along the first direction is independent of movement of the bowtie filter assembly along the second direction, and wherein the first and second directions are orthogonal to each other.

[0007] In another embodiment, a method for performing collimator bowtie filter alignment is provided. The method includes obtaining air scan data acquired via air scan using a computed tomography (CT) imaging system at a processor, wherein the bowtie filter is moved outside the field of view of an X-ray beam emitted by an X-ray source of the CT imaging system prior to the air scan to obtain the air scan data, wherein the bowtie filter is disposed within a bowtie filter assembly disposed within a collimator housing, and wherein the bowtie filter assembly is configured to move within the collimator housing along a first direction and a second direction, the first direction being orthogonal to the second direction. The method also includes obtaining alignment data acquired via air scan using the CT imaging system at a processor, wherein the bowtie filter is moved along the second direction into the scan plane prior to the alignment scan to obtain the air scan data. The method further includes calculating, via the processor, an offset distance between the bowtie filter and the beamline path of the X-ray beam. The method also includes comparing, via the processor, the offset distance with an acceptable range for a desired centering position of the bowtie filter within the X-ray beam. The method further includes, when the offset distance is outside an acceptable range, calculating via a processor the distance by which to move the bowtie filter along a second direction to center the bowtie filter within the X-ray beam. The method even includes moving the bowtie filter by that distance along the second direction in response to a control signal from the processor. Attached Figure Description

[0008] These and other features, aspects, and advantages of the invention will be better understood when the following detailed description is read with reference to the accompanying drawings, in which the same reference numerals denote the same parts throughout the drawings, wherein:

[0009] Figure 1 This is a combined drawing view and block diagram of a computed tomography (CT) imaging system as discussed in this article;

[0010] Figure 2 This is a schematic diagram of an X-ray source and a multi-row X-ray detector (e.g., as observed in the XY plane) according to various aspects of this disclosure;

[0011] Figure 3 This is a schematic diagram of an X-ray source and a multi-row X-ray detector (e.g., as observed in the YZ plane) according to various aspects of this disclosure;

[0012] Figure 4 This is a perspective view of an additively manufactured component with a collimator mounted on a printing base according to various aspects of this disclosure;

[0013] Figure 5 It is a cross-sectional view of a portion of the wall of an additively manufactured component of a collimator (e.g., a solid structure) according to various aspects of this disclosure;

[0014] Figure 6 This is a cross-sectional view of a portion of the wall of an additively manufactured component of a collimator (e.g., a grid structure) according to various aspects of this disclosure;

[0015] Figures 7 to 10 These are different perspective views of the collimator housing manufactured by additive manufacturing according to various aspects of this disclosure;

[0016] Figure 11 Based on all aspects of this disclosure Figures 7 to 10 Stress diagram of the collimator housing in the image;

[0017] Figure 12 Based on all aspects of this disclosure Figures 7 to 10 Deformation diagram of the collimator housing in the image;

[0018] Figure 13 This is a perspective view of an additively manufactured perforated carrier plate according to various aspects of this disclosure;

[0019] Figure 14 yes Figure 13 Side view of the additively manufactured perforated carrier plate;

[0020] Figure 15 yes Figure 13 A cross-sectional view of a portion of the additively manufactured perforated carrier plate taken along line AA;

[0021] Figure 16 yes Figure 13 A perspective view of a portion of the mounting bracket for an additively manufactured orifice carrier plate;

[0022] Figure 17 It is according to the various aspects of this disclosure that the actuator is connected. Figure 13 A perspective view of the mounting bracket for the additively manufactured carrier plate;

[0023] Figure 18 It is according to the various aspects of this disclosure that the actuator is connected. Figure 13 A perspective view of another mounting bracket for the additively manufactured carrier plate;

[0024] Figure 19 This is an exploded view of the built-in alignment mechanism for moving the bowtie filter assembly within the collimator housing, according to various aspects of this disclosure.

[0025] Figure 20 This is a perspective view of a collimator housing according to various aspects of the present disclosure, the collimator housing having a bow filter assembly located within and connected to a built-in alignment mechanism;

[0026] Figure 21 This is a front view of the collimator housing, which has a... Figure 20 The bow filter assembly (e.g., a bow filter assembly with a second wall closer to the collimator housing) is located within the built-in alignment mechanism and connected to that mechanism.

[0027] Figure 22 This is a front view of the collimator housing, which has a collimator housing located at... Figure 20 The bow filter assembly (e.g., a bow filter assembly with a third wall closer to the collimator housing) is located within the built-in alignment mechanism and connected to that mechanism.

[0028] Figure 23 This is a cross-sectional side view of a collimator housing according to various aspects of the present disclosure, the collimator housing having a bow filter assembly (e.g., having a bow filter assembly in the scanning plane) located within and connected to a built-in alignment mechanism.

[0029] Figure 24 This is a perspective view of the collimator housing, which has a location located at... Figure 23 The bow filter assembly (e.g., having a bow filter assembly in the scanning plane) is built into the alignment mechanism and connected to the mechanism.

[0030] Figure 25 This is a cross-sectional side view of the collimator housing, which has a location located at... Figure 23The bow filter assembly (e.g., having a bow filter assembly outside the scanning plane) is located within the built-in alignment mechanism and connected to that mechanism.

[0031] Figure 26 This is a perspective view of the collimator housing, which has a location located at... Figure 23 The bow filter assembly (e.g., having a bow filter assembly outside the scanning plane) is located within the built-in alignment mechanism and connected to that mechanism.

[0032] Figure 27 This is a perspective view of the assembled front collimator according to various aspects of this disclosure;

[0033] Figure 28 This is an exploded view of another built-in alignment mechanism for moving the bowtie filter assembly within the collimator housing, according to various aspects of this disclosure.

[0034] Figure 29 This is a front perspective view of a collimator housing according to various aspects of this disclosure, the collimator housing having a bow filter assembly located within and connected to a built-in alignment mechanism (e.g., showing lateral movement of the bow filter assembly).

[0035] Figure 30 This is a rear perspective view of a collimator housing according to various aspects of the present disclosure, the collimator housing having a bow filter assembly located within and connected to a built-in alignment mechanism (e.g., showing lateral movement of the bow filter assembly).

[0036] Figure 31 This is a perspective view of the assembled front collimator according to various aspects of this disclosure;

[0037] Figure 32 This is an exploded view of another built-in alignment mechanism for moving the bowtie filter assembly within the collimator housing, according to various aspects of this disclosure.

[0038] Figure 33 It is based on various aspects of this disclosure regarding the operation between the locked and unlocked positions. Figure 32 A schematic diagram of the guide pins of the built-in alignment mechanism;

[0039] Figure 34 This is a perspective view of the assembled front collimator according to various aspects of this disclosure; and

[0040] Figure 35 This is a flowchart of a method for centering a bow filter according to various aspects of this disclosure. Detailed Implementation

[0041] One or more specific implementations will be described below. To provide a concise description of these implementations, not all features of an actual implementation will be described in this specification. It should be understood that in the development of any such actual implementation, as in any engineering or design project, many implementation-specific decisions must be made to achieve the developer's specific objectives, such as complying with system-related and business-related constraints that may differ from implementation to implementation. Furthermore, it should be understood that such development efforts may be complex and time-consuming, but remain routine tasks of design, fabrication, and manufacturing for those skilled in the art who benefit from this disclosure.

[0042] When describing the elements of various embodiments of the subject matter of this invention, the articles “a,” “an,” “the,” and “the” are intended to indicate the presence of one or more of the stated elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that additional elements may be present in addition to the listed elements. Furthermore, any numerical examples in the following discussion are intended to be non-limiting, and therefore the additional numerical values, ranges, and percentages are within the scope of the disclosed embodiments.

[0043] While the aspects discussed below are provided within the context of medical imaging, it should be understood that this technique is not limited to such a medical context. In fact, the examples and explanations provided in this medical context are merely for the purpose of facilitating explanation by providing examples of real-world implementations and applications. However, this method can also be used in other contexts, such as tomographic image reconstruction from industrial computed tomography (CT) used for non-destructive inspection of manufactured parts or finished products (i.e., quality control or quality audit applications) and / or non-invasive inspection of packages, boxes, luggage, etc. (i.e., security screening or screening applications). Generally, this method can be used in any imaging or screening context or image processing field that utilizes collimator control of X-ray beam size.

[0044] This disclosure provides a built-in alignment mechanism disposed within a precollimator (e.g., an additively manufactured precollimator) for precise and easy adjustment of the collimator (e.g., adjusting a bowtie filter integrated with the precollimator) during system alignment. Specifically, the built-in alignment mechanism enables adjustment of the bowtie filter in lateral and transverse directions (e.g., aligning relative to the X-ray beam path to provide excellent image quality) independently of each other. The configuration of the built-in alignment mechanism also enables adjustment of the bowtie filter from outside the collimator housing (e.g., via an actuator mechanism) without having to remove or detach the sub-component (e.g., the bowtie filter) from the collimator during system alignment. Furthermore, the built-in alignment mechanism is configured for use with different types of bowtie filters and is scalable for use with different imaging platforms.

[0045] Taking into account the foregoing and referring to Figure 1 A CT imaging system 10 is illustrated by way of example. The CT imaging system includes a gantry 12. The gantry 12 has an X-ray source 14 that projects a beam of X-rays 16 toward a detector assembly 15 on an opposite side of the gantry 12. The X-ray source 14 projects the beam of X-rays 16 through a pre-collimator or collimator assembly 13, which determines the size of the beam of X-rays 16. The detector assembly 15 includes a collimator assembly 18 (rear collimator assembly), a plurality of detector modules 20 (e.g., detector elements or sensors), and a data acquisition system (DAS) 32. The plurality of detector modules 20 detect the projected X-rays passing through a patient 22, and the DAS 32 converts the data into a digital signal for subsequent processing. Each detector module 20 in a conventional system generates an analog electrical signal representing the intensity of the incident X-ray beam and therefore the intensity of the attenuated beam as the incident X-ray beam passes through the patient 22. During the scan to acquire X-ray projection data, the gantry 12 and the components mounted thereon rotate about a rotation center 25 (e.g., an isocenter) to collect attenuation data from multiple viewpoints relative to the imaging volume.

[0046] The rotation of gantry 12 and the operation of X-ray source 14 are controlled by control mechanism 26 of CT system 10. Control mechanism 26 includes X-ray controller 28, which provides power and timing signals to X-ray source 14; collimator controller 29, which controls the aperture width of front collimator 13 (and therefore the beam size of X-ray 16); and gantry motor controller 30, which controls the rotational speed and position of gantry 12. Image reconstructor 34 receives sampled and digitized X-ray data from DAS 32 and performs high-speed reconstruction. The reconstructed image is applied as input to computer 36, which stores the image in mass storage device 38. Computer 36 also receives commands and scan parameters from operator via console 40. Associated display 42 allows operator to view reconstructed images and other data from computer 36. Computer 36 uses commands and parameters provided by operator to provide control signals and information to DAS 32, X-ray controller 28, collimator controller 29, and gantry motor controller 30. Additionally, computer 36 operates a workbench motor controller 44, which controls an electric workbench 46 to position the patient 22 and the gantry 12. Specifically, the workbench 46 moves various parts of the patient 22 through openings or apertures 48 in the gantry.

[0047] Considering the previous discussion of the overall imaging system 10, and turning to... Figure 2 and Figure 3 Examples of X-ray source 14 and detector assembly 15 (e.g., X-ray detector with multiple rows 50) are respectively in the XY plane ( Figure 2) and YZ plane ( Figure 3 As shown in the diagram. For ease of explanation, the rotating gantry 12 with the X-ray source 14 is... Figure 1 The position shown is rotated to the top of the frame (+Y direction). As depicted, the pre-collimator 13 is positioned between the X-ray source 14 and the detector assembly 15, and defines the shape of the X-ray beam 52. Specifically, the pre-collimator 13 has an opening or hole 54 between one of the collimator blades 56 (e.g., ...). Figure 3 The depicted X-ray beam 52 is formed. The field of view 24 and beam width 58 corresponding to the size of the X-ray beam 52 intended for patient scanning are also shown. Proper positioning of the collimator blades 56 is important to ensure the patient receives the correct radiation dose and the correct area is scanned. Figure 2 and Figure 3 The image shows the shapes of the blade 56 in different orientations. For example, the blade 56 is typically curved in the XY plane, where the circular leading edge in the YZ plane determines the bundle size. Many other possible shapes of the blade in the XY plane include flat and angled shapes; for example, the leading edge in the YZ plane can also be rectangular or triangular.

[0048] Figure 4 This is a perspective view of the additively manufactured component, the front collimator, mounted on the printing base 60. (See image.) Figure 4 As shown, the additively manufactured components of the collimator include a collimator housing 62, an orifice carrier plate 64, a motor mounting plate 66, and a sensor plate 68. In some embodiments, other components of the collimator (e.g., a bow filter, a plate or cover for housing the bow filter, a cover plate for the collimator housing 62, etc.) can be additively manufactured. The layout of the additively manufactured components on the printing base is an example of an additive manufacturing or 3D printing layout configuration for components of the collimator. Other layout configurations can be utilized. Each additively manufactured component is made of a lead-free material (e.g., to mitigate the occupational hazards posed by the presence of lead). In some embodiments, the components may be formed from a metallic material (e.g., via direct metal laser sintering). In some embodiments, part or all of the additively manufactured component may be made of, for example, Figure 5 The solid structure 70 shown is made of solid material. For example, the entire sensor plate 68 is made of solid material. Solid structures can function in X-ray blocking. In some embodiments, part or all of the additively manufactured component may be made of materials such as... Figure 6 The grid structure 72 shown is made of a grid structure. For example, the entire motor mounting plate 66 is made of a grid structure. The grid structure allows for weight reduction. The grid structure may include a honeycomb structure or other grid structures. As described in more detail below, a portion of the collimator housing 62 and the orifice carrier plate 64 is made of a grid structure, while other portions are made of a solid structure.

[0049] Figures 7 to 10 These are different perspective views of the additively manufactured collimator housing 62. The collimator housing 62 includes a plurality of walls, including: a first wall 74 configured to face an X-ray source when the collimator is attached to a frame; a second wall 76 and a third wall 78 adjacent to the first wall 74; and a fourth wall 80 extending adjacent to the first wall 74 between the second wall 76 and the third wall 78. Each wall 74, 76, 78, 80 includes a structural rib 82 (e.g., integral with the corresponding wall 74, 76, 78, 80) extending along at least one edge 84 of the wall 74, 76, 78, 80. For example, the first wall 74 includes a single structural rib 86 extending along the entire edge 88. The second wall 76 includes a first structural rib 90 extending along the entire first edge 92 (and from the rib 86) and a second structural rib 94 extending along the entire second edge 96 (and from the rib 90). The third wall 86 includes a first structural rib 98 extending along the entire first edge 100 (and from rib 86) and a second structural rib 102 extending along the entire second edge 104 (and from rib 98). The fourth wall 80 includes ribs 94 and 102 extending along portions of edge 106 adjacent to the second wall 76 and the third wall 78. The structural ribs 86 reduce deflection and eliminate stress concentration at the corners of the collimator housing 62. Additionally, the ribs 82 provide mounting surfaces for the cover to be attached to the collimator housing 62.

[0050] Additional structural ribs 108 (e.g., integral with the first wall 74) are disposed on the inner surface of the first wall 74 and extend toward the interior space 110 of the collimator housing 62. The structural ribs 108 extend around the periphery of the opening 112 to receive the X-ray beam from the X-ray source when the collimator is coupled to the frame and the X-ray source. Specifically, the structural ribs 108 extend between structures 114 (e.g., integral with the first wall 74) to allow the collimator housing 62 to be coupled to the X-ray source via fasteners. Structures 114 also extend toward the interior space 110. The structural ribs 108 reduce deflection and stress caused by centrifugal force from the tube (X-ray source). The structural ribs 108 also contribute to the stiffness of the collimator housing 62. The structural ribs 108 are designed to be self-supporting during additive manufacturing.

[0051] The influence of structural ribs 86 and 108 on the deflection and stress on the straightener housing 62 Figure 11 and Figure 12 As shown in the image. Figure 11 and Figure 12 These are stress and deformation diagrams of the collimator housing 62 when it is connected to the frame and subjected to various loads during frame rotation. Ribs 86 and 108 apply a uniform stress distribution across the entire collimator housing 62, with localized stress applied only in small areas, such as... Figure 11As shown. Ribs 86 and 108 also apply a uniform and symmetrical deflection to the collimator housing 62, as... Figure 12 As shown.

[0052] Back Figures 7 to 10 A sac 116 (e.g., integral with the first wall 74) disposed on the inner surface of the first wall 74 has an opening 112 on its side and is configured such that guides for moving the bow filter assembly can extend through them. The sac 116 also extends toward the inner space 110.

[0053] In addition, a reinforcing member 118 (e.g., integral with the fourth wall 80) is disposed on the inner surface of the fourth wall 80. As shown, the reinforcing member 118 forms an X-shaped pattern. The pattern formed by the reinforcing member 118 can be varied. The reinforcing member 118 increases or provides stiffness to the collimator housing 62. Furthermore, the reinforcing member 118 enables the collimator housing 62 to avoid warping and shrinkage during manufacturing and post-processing operations. The reinforcing member 118 extends between structures 120 (e.g., integral with the fourth wall 80) that enable the collimator housing 62 to be coupled to a frame bearing. Some of the structures 120 are also partially disposed on the inner surfaces of the second wall 76 or the third wall 78. The structures 120 also extend toward the interior space 110. An additional structure 122 (e.g., integral with the fourth wall 80) extending toward the interior space 110 on the inner surface of the fourth wall 80 is configured to receive fasteners for coupling the bowtie filter assembly to the collimator housing 62.

[0054] Furthermore, a side structure 124 (e.g., integral with the second wall 76) on the inner surface of the second wall 76 extends toward the interior space 110. The side structure 124 is configured to connect to a track guide (e.g., directly connected to the track guide) and an actuator (e.g., indirectly connected to the actuator via the track guide) for movement of the orifice plate. A side structure 126 (e.g., integral with the third wall 78) on the inner surface of the third wall 78 extends toward the interior space 110. The side structure 126 is also configured to connect to a track guide (e.g., directly connected to the track guide) and an actuator (e.g., indirectly connected to the actuator via the track guide) for movement of the orifice plate.

[0055] In some embodiments, some structures extending from the inner surfaces of walls 74, 76, 78, and 100 may be located in different areas or may not be present. Additionally, due to the ribs 82 along the edges and other structures extending from walls 74, 76, 78, and 80 toward the interior space 110, the corresponding thickness 128 of each wall 74, 76, 78, and 80 may vary along its length. Furthermore, for some walls, such as the fourth wall 80, in areas where no structures or ribs are provided, the thickness 128 of the fourth wall is as follows: Figure 10The variations are shown. In addition, the corresponding thickness 128 of each wall 74, 76, 78 and 80 (in areas where no structure or ribs are provided) can be about 3.5 mm (which is about 5% to 35% of the thickness of a typical collimator housing wall).

[0056] In addition, some parts of the collimator housing 62 are made of solid structure (such as...). Figure 5 As shown), and some parts of the collimator housing 62 are made of a grid structure (as shown). Figure 6 (As shown). Regarding the first wall 74, structure 114 and rib 108 are made of solid structure, while rib 88, the housing 116, and the remainder of the first wall are made of grid structure. Regarding the second wall 76, the first portion 130 of the side structure 124 (e.g., directly connected to the track guide) and ribs 90, 94 are made of grid structure. The second portion 132 of the side structure 124 (e.g., closest to the inner surface of the second wall 76) and the remainder of the second wall 76 are made of solid structure. Regarding the third wall 78, ribs 98, 102, side structure 126, and the corner portion 134 of the third wall 78 are made of grid structure. The remainder of the third wall 78 is made of solid structure. Regarding the fourth wall 80, the portions of ribs 94, 102 along edge 106 are made of grid structure. The remainder of the fourth wall 80 (including reinforcement 118, structure 120, and structure 122) is made of solid structure.

[0057] An integrated, gapless X-ray shield is provided in sections 74, 76, 78, and 80 using a solid structure, eliminating the need to attach additional attenuation material to the collimator housing 62. The gapless X-ray shield prevents X-rays from leaving the front collimator, except through the aperture of the aperture carrier plate 64. The use of a grid structure allows for a lighter collimator housing 62 and collimator. For example, the collimator housing 62 can weigh approximately 3.3 kg, which is about 23.5% of the weight of a typical collimator housing. Additionally, the footprint of the collimator housing 62 and collimator is reduced. Due to the reduced footprint and weight of the collimator, it can be operated with one hand and easily rotated when attached to the frame.

[0058] Figure 13 and Figure 14 This is a view of an additively manufactured aperture carrier 64. The aperture carrier 64 includes a plate portion 136 integrated as a single piece and a mounting bracket 138. The plate portion 136 includes a plurality of apertures 140 with different widths 142. The aperture 140 used during X-ray emission determines the size of the X-ray beam emitted from the collimator. The thickness 143 of the plate portion 136 varies along its length. The plate portion 136 is made of a solid structure (for X-ray attenuation), as... Figure 15 As shown. Back Figure 13 and Figure 14Mounting brackets 138 are located on the longitudinal ends 144, 146 of the plate portions 136. Each mounting bracket 138 includes a first portion 148 extending perpendicularly to the plate portion 136 and a second portion 150 extending parallel to the plate portion 136 and toward the other mounting bracket 138. Portions 148, 150 are both made of a grid structure because these areas are not critical for X-ray attenuation. Figure 16 The grid structure in the second part 150 of the mounting bracket 138 is shown.

[0059] The second portion 150 of the mounting bracket 138 is configured to be mounted to an actuator and a track guide that moves the orifice plate 64 into and out of the path of the X-ray beam (e.g., mechanically or electrically). Figure 17 The second part 150 of the mounting bracket 152 is shown as being connected to the actuator 154 (e.g., via a fastener) (see [link]). Figure 13 and Figure 14 The actuator 54 is coupled to the track guide 156. The track guide 156 is coupled to the side structure 124 within the collimator housing 62. The actuator 154 moves along the track guide 56 to move the orifice carrier plate 64. Figure 18 The second part 50 of the mounting bracket 158 ​​is shown, which is connected to the actuator 160 (via fasteners) (see...). Figure 13 and Figure 14 The actuator is coupled to the track guide 162. The track guide 162 is coupled to the side structure 126 within the collimator housing 62. The actuator 160 can be driven by a motor, which in turn drives the two actuators 154, 160 to move along their respective track guides 156, 162, and thus drives the movement of the orifice carrier plate 64.

[0060] Back Figure 13 and Figure 14 The additively manufactured orifice carrier 64 can weigh approximately 0.3 kg, which is about 23% of the weight of the multiple components that form a typical orifice carrier in a typical collimator. The additively manufactured additional carrier 64 eliminates the spacers and pins typically used to mount the orifice carrier within a typical collimator.

[0061] Utilizing additively manufactured components enables significant reductions in mass (e.g., a 70% reduction compared to a typical collimator, such as a lower-cost collimator), assembly time (e.g., a 50% reduction compared to a typical collimator), cost reduction (e.g., a 25% reduction compared to a typical collimator), and increased part counting efficiency (e.g., an 81% reduction in total parts compared to a typical collimator). Furthermore, the mass reduction of collimators using additively manufactured components can reduce the mass of the CT rotating gantry, which translates to less power consumption by the gantry actuators, resulting in a significant reduction in operating costs (e.g., a 17% to 18% reduction compared to a typical collimator).

[0062] In addition to additively manufactured components, the precollimator disclosed herein includes a built-in alignment mechanism for adjusting the positioning of the bow filter assembly. Figure 19 This is an exploded view of the built-in alignment mechanism 164 for moving the bowtie filter assembly 166 within the collimator housing 62. The bowtie filter assembly 166 includes a substrate or filter mounting plate 168, a bowtie filter 170 (e.g., made of polytetrafluoroethylene), and a cover 172 (e.g., a front cover). The substrate 168 supports the bowtie filter 170 and components of the built-in alignment mechanism 164. The substrate 168 and the cover 172 partially enclose the bowtie filter 170 therein. The cover 172 does not extend around the top and bottom portions of the bowtie filter 170. A radiation shielding layer 174 (e.g., made of a tungsten-based polymer) is disposed on the surface of the substrate 168 that directly contacts the bowtie filter 170. A radiation shielding layer 176 is disposed on the surface of the cover 172 that directly contacts the bowtie filter 170. The substrate 168 and the cover 172 are configured to accommodate different types of bowtie filters 170. The bow filter 170 is attached to or mounted to the substrate 168 via fasteners 178 (e.g., screws) passing through corresponding openings on the bow filter 170 and the substrate 168. The cover 172 is attached to or mounted to the substrate 168 to enclose the bow filter 170 via fasteners (not shown, e.g., screws) passing through corresponding openings on the cover 172 and the substrate 168.

[0063] The built-in alignment mechanism 164 includes an adjustment mechanism 180 configured to move the bowtie filter 170 along a first direction 182 (e.g., a lateral direction or X-direction) and a second direction 184 (e.g., a transverse direction or Z-direction, which is the same as the direction of movement of the CT table). Movement along the lateral direction 182 is independent of movement along the transverse direction 184. Movement along the lateral direction 182 occurs between the second wall 76 and the third wall 78 of the collimator housing 62. Movement along the transverse direction 184 occurs toward and away from the fourth wall 80 of the collimator housing 62. The lateral direction 182 is orthogonal to the transverse direction 184.

[0064] The adjustment mechanism 180 includes a frame 186 that is part of and extends from the base plate 168. The single frame 186 allows for independent movement in the lateral direction 182 and the transverse direction 184. The frame 186 extends in a direction 184 parallel to the second wall 76 and the third wall 78. The frame 186 includes a slot 188 and a pair of openings 190, 192. The slot 188 is positioned closer to the fourth wall 80 of the collimator housing 62 than the openings 190, 192.

[0065] The built-in alignment mechanism 164 includes polymer guides 194, 196, and 198 for movement of the bow filter assembly 166 thereal. Respective portions (e.g., threaded portions) of the polymer guides 194 and 196 extend through openings in the substrate 168 and are engaged to the substrate 168 on its back side via fasteners 200 (e.g., nuts). The polymer guides 194 and 196 extend through a receptacle 116 on the first wall 74 (see [link to receptacle]). Figure 8 The polymer guide 198 is attached to the structure on the fourth wall 80 (e.g., Figure 8 (Structure 122 in the diagram). Polymer guide 198 extends through opening 202 in substrate 168. Receptacle 116 and opening 202 define the range of movement of bow filter assembly 166 in the lateral direction 182. Fasteners 204 (e.g., mounting screws) attached to the ends 206 of polymer guides 194, 196 (further away from fourth wall 80) limit the range of movement of bow filter assembly 166 in the lateral direction 184. These fasteners 204 also securely hold bow filter 170 in the scanning plane during operation. In some embodiments, fasteners 204 are loosened before adjustment in the lateral direction 182. In some embodiments, fasteners 204 are removed before adjustment in the lateral direction 184.

[0066] The adjustment mechanism 180 includes an adjustment screw 208 that adjusts the movement of the bowtie filter assembly 166 within the collimator housing 62 in the lateral direction 182. The adjustment screw 208 adjusts the bowtie filter assembly 166 such that the bowtie filter 170 is isocenter to the X-ray beam. A portion of the adjustment screw 208 extends through a nut 210 (e.g., a locking nut) on the outside of the collimator housing 62 and into the internal space 110 of the collimator housing 62 (via an opening in the second wall 76). Within the collimator housing 62, this portion of the adjustment screw 208 extends through a slot 188 and is secured to the frame 186 via a fastener 212 (e.g., a nut). Rotation of the adjustment screw 208 moves the bowtie filter assembly 166 in the lateral direction 182. Each end of the slot 188 serves to limit the movement of the bowtie filter assembly 166 in the lateral direction 184. Once adjustment is complete, the locking nut 210 can be used to secure the position of the bowtie filter assembly 166. The actuation of the adjusting screw 208 can be mechanical. In some embodiments, the actuation of the adjusting screw 208 can be via a motorized actuator 213 coupled to the adjusting screw 208 (in response to a response from...). Figure 1 The control signals of the collimator controller 29's processing circuit are processed automatically. Figure 20 As shown, the rotation of adjusting screw 208 in the circumferential direction 218 toward the fourth wall 80 causes the bow filter assembly 166 to move in the lateral direction 182 (+X direction) toward the second wall 76, as... Figure 21 As shown. Figure 20 As shown, the rotation of adjusting screw 208 in the circumferential direction 220 away from the fourth wall 80 causes the bow filter assembly 166 to move in the lateral direction 182 (-X direction) toward the third wall 78, as... Figure 22 As shown.

[0067] Back Figure 19 The adjustment mechanism 180 also includes a locking pin 214 coupled to a locking pin spring mechanism 216, which adjusts the movement of the bowtie filter assembly 166 within the collimator housing 62 in the lateral direction 184. The locking pin spring mechanism 216 is located on the outside of the collimator housing 62. The locking pin 214 extends from the outside of the collimator housing 62 into the internal space 110 of the collimator housing 62 (via an opening in the second wall 76). A portion of the locking pin 214 extends through one of the openings 190, 192 of the frame 186. When the locking pin 214 is positioned in the opening 190, the bowtie filter assembly 166 is positioned such that the bowtie filter 170 is aligned within the scanning plane 217 (via the opening 112 in the first wall 74), as... Figure 23 and Figure 24As shown. When the locking pin 214 is positioned in the opening 192, the bowtie filter assembly 166 is positioned closer to the fourth wall 80 and outside the scanning plane 217, as... Figure 25 and Figure 26 As shown. Movement of the locking pin mechanism 216 away from the collimator housing 62 withdraws the locking pin 214 from any of the openings 190, 192 where it is disposed, and allows the bowtie filter assembly 166 to move laterally 184 along the polymer guides 194, 196, and 198. Releasing the locking pin mechanism 216 allows the locking pin 214 to extend through the desired opening 190, 192 when aligned with it. Actuation of the locking pin mechanism 216 can be mechanical or automatic via a motorized actuator.

[0068] Figure 27 This is a perspective view of the assembled front collimator 13. The collimator 13 includes the additively manufactured collimator housing 62, the additively manufactured orifice carrier plate 64, and the additively manufactured motor mounting plate 66. Additionally, the collimator 13 includes a built-in alignment mechanism 164, an adjustment mechanism 180, and a motor 222, which is coupled to the motor mounting plate 66 and configured to move the orifice carrier plate 64 (via actuators and track guides).

[0069] Figure 28 This is an exploded view of another built-in alignment mechanism 224 for moving the bowtie filter assembly 166 within the collimator housing 62. The built-in alignment mechanism 224 includes a base plate 226 coupled to the bowtie filter assembly 166. The bowtie filter assembly 166 includes a filter mounting plate 228, a bowtie filter 170 (e.g., made of polytetrafluoroethylene), and a cover 172 (e.g., a front cover). The base plate 168 supports components of the bowtie filter assembly 166 and the built-in alignment mechanism 224. The filter mounting plate 228 and the cover 172 partially enclose the bowtie filter 170 therein. The cover 172 does not extend around the top and bottom portions of the bowtie filter 170. A radiation shielding layer 174 (e.g., made of a tungsten-based polymer) is disposed on the surface of the filter mounting plate 228 that directly contacts the bowtie filter 170. A radiation shielding layer 176 is disposed on the surface of the cover 172 that directly contacts the bowtie filter 170. Filter mounting plate 228 and cover 172 are configured to accommodate different types of bow filters 170. Bow filters 170 are attached to or mounted to filter mounting plate 228 via fasteners 178 (e.g., screws) passing through corresponding openings on bow filters 170 and filter mounting plate 228. Cover 172 is attached to or mounted to filter mounting plate 228 to enclose bow filters 170 via fasteners (not shown, e.g., screws) passing through corresponding openings on cover 172 and filter mounting plate 228.

[0070] The built-in alignment mechanism 224 includes an adjustment mechanism 180 configured to move the bowtie filter assembly 166 along a first direction 182 (e.g., a lateral direction) and a second direction 184 (e.g., a transverse direction). Movement along the lateral direction 182 is independent of movement along the transverse direction 184. Movement along the lateral direction 182 occurs between the second wall 76 and the third wall 78 of the collimator housing 62. Movement along the transverse direction 184 occurs toward and away from the fourth wall 80 of the collimator housing 62. The lateral direction 182 is orthogonal to the transverse direction 184.

[0071] The built-in alignment mechanism 224 includes surface contact track guides 230 and 232 for moving the bowtie filter assembly 166 and the substrate 226 thereal. The surface contact track guides 230 and 232 are respectively coupled to mounting plates 234 and 236, which are mounted to the fourth wall 80 of the collimator housing 62. The substrate 226 is disposed on the surface contact track guides 230 and 232. The adjustment mechanism 180 includes an actuator screw assembly 238, which includes an actuator screw 240, a knob 242 coupled to the actuator screw 240, and a receiving seat 244 including a threaded portion. The receiving seat 244 is mounted to a receiving portion 246 of the substrate 226, the receiving portion including an opening for the threaded portion of the receiving seat 244. The actuator screw 240 is configured to move into and out of the threaded portion of the housing to move the bowtie filter assembly 166 in the lateral direction 184 (e.g., into and out of the scanning plane) along the surface contact guides 230, 232. Actuation of the actuator screw 240 can be accomplished mechanically or automatically via a motorized actuator. Figure 29 Actuation of the actuator screw 240, indicated by arrow 248 (via knob 242), causes movement of the bowtie filter assembly 166 and substrate 226 in the lateral direction 184. Fasteners 204 (e.g., mounting screws) attached to the ends 206 of the surface contact track guides 230, 232 (further away from the fourth wall 80) limit the range of movement of the bowtie filter assembly 166 in the lateral direction 184. These fasteners 204 also securely hold the bowtie filter 170 in the scanning plane during operation.

[0072] The adjustment mechanism 180 includes a frame 250 that is part of and extends from the filter mounting plate 228. The frame 250 allows the bowtie filter assembly 166 to move in a lateral direction 182, independent of movement in the transverse direction 184. The frame 250 extends in a direction 184 parallel to the second wall 76 and the third wall 78. The frame 250 includes a slot 252.

[0073] The adjustment mechanism 180 includes an adjustment screw 208 that adjusts the movement of the bowtie filter assembly 166 within the collimator housing 62 in the lateral direction 182 (without movement of the substrate 226). The adjustment screw 208 is capable of adjusting the bowtie filter assembly 166 such that the bowtie filter 170 is isocenter of the X-ray beam. A portion of the adjustment screw 208 extends through a nut 210 (e.g., a locking nut) on the outside of the collimator housing 62 and enters the internal space 110 of the collimator housing 62 (via an opening in the second wall 76). Within the collimator housing 62, this portion of the adjustment screw 208 extends through a slot 252 and is secured to the frame 250 via a fastener 212 (e.g., a nut). Rotation of the adjustment screw 208 moves the bowtie filter assembly 166 in the lateral direction 182. Each end of the slot 252 serves as a constraint on the movement of the bowtie filter assembly 166 in the lateral direction 184. Once adjustment is complete, the locking nut 210 can be used to secure the position of the bowtie filter assembly 166. The actuation of the adjusting screw 208 can be mechanical. In some embodiments, the actuation of the adjusting screw 208 can be via a motorized actuator 213 coupled to the adjusting screw 208 (in response to a response from...). Figure 1 The control signals of the collimator controller 29's processing circuit are processed automatically. Figure 30 As shown, rotation of the adjusting screw 208 in the circumferential direction (indicated by arrow 254) toward the fourth wall 80 causes the bowtie filter assembly 166 to move in the lateral direction 182 toward the second wall 76, while rotation of the adjusting screw 208 in the circumferential direction away from the fourth wall 80 causes the bowtie filter assembly 166 to move in the lateral direction 182 toward the third wall 78.

[0074] Figure 31 This is a perspective view of the assembled front collimator 13. The collimator 13 includes the additively manufactured collimator housing 62, the additively manufactured orifice carrier plate 64, and the additively manufactured motor mounting plate 66 described above, with some modifications. For example, the orifice carrier plate 64 does not include a mounting bracket. The plate portion 136 of the orifice carrier plate 64 is connected (e.g., indirectly connected via a track guide and actuator) to the integral side structures 256, 258 of the collimator housing 62. Figures 7 to 10 Compared to similar side structures in the collimator housing 62, side structures 256, 258 are positioned further away from the first wall 74. Additionally, the collimator 13 includes a built-in alignment mechanism 224, an adjustment mechanism 180, and a motor 222, which is coupled to a motor mounting plate 66 and configured (via an actuator and a track guide) to move the orifice carrier plate 64.

[0075] Figure 32This is an exploded view of another built-in alignment mechanism 260 for moving the bowtie filter assembly 166 within the collimator housing. The bowtie filter assembly 166 includes a substrate or filter mounting plate 262, a bowtie filter 170 (e.g., made of polytetrafluoroethylene), and a cover 172 (e.g., a front cover). The filter mounting plate 262 and the cover 172 partially enclose the bowtie filter 170 therein. The cover 172 does not extend around the top and bottom portions of the bowtie filter 170. In some embodiments, a radiation shielding layer (e.g., made of a tungsten-based polymer) is disposed on the surface of the filter mounting plate 262 that directly interacts with the bowtie filter 170. In some embodiments, a radiation shielding layer is disposed on the surface of the cover 172 that directly interacts with the bowtie filter 170. The filter mounting plate 262 and the cover 172 are configured to accommodate different types of bowtie filters 170. The bow filter 170 is attached to or mounted to the filter mounting plate 262 via fasteners 178 (e.g., screws) passing through corresponding openings on the bow filter 170 and the filter mounting plate 228. The cover 172 is attached to or mounted to the filter mounting plate 262 to enclose the bow filter 170 via fasteners (not shown, e.g., screws) passing through corresponding openings on the cover 172 and the filter mounting plate 262.

[0076] The built-in alignment mechanism 260 includes an adjustment mechanism 180 configured to move the bowtie filter assembly 166 along a first direction 182 (e.g., a lateral direction) and a second direction 184 (e.g., a transverse direction). Movement along the lateral direction 182 is independent of movement along the transverse direction 184. Movement along the lateral direction 182... Figures 7 to 10 The movement occurs between the second wall 76 and the third wall 78 of the collimator housing 62. The movement is directed towards and away from the collimator housing 62 in the lateral direction 184. Figures 7 to 10 The collimator housing 62 is constructed on the fourth wall 80. The lateral direction 182 is orthogonal to the transverse direction 184.

[0077] The built-in alignment mechanism 260 includes guides 264, 266 for moving the bow filter assembly 166 thereal. Guides 264, 266 are coupled to extensions 268, 270, which are part of the filter mounting plate 262 and extend in a lateral direction 184 (e.g., away from). Figures 7 to 10 The fourth wall 80). Guides 264 and 266 support the bow filter assembly 166. Guides 264 and 266 extend through Figures 7 to 10 The housing 116 on the first wall 74 of the collimator housing 62.

[0078] The adjustment mechanism 180 includes three guide pins 272 that extend through corresponding receptacles 274 of the filter mounting plate 262 and into corresponding quarter-circle bushings 276 (e.g., made of abrasion-resistant material) disposed within a support pad 278. The support pad 278 is coupled to a fastener 280. Figures 7 to 10 The fourth wall 80 of the collimator housing 62. The housing 274 allows the bowtie filter assembly 166 to move in the lateral direction 182 and the transverse direction 184. (As...) Figure 33 As shown, guide pin 272 is configured to rotate a quarter turn in either direction indicated by arrow 280 between locked position 284 and unlocked position 286. Each guide pin 272 includes a first set of protrusions 288 and a second set of protrusions 290 at different axial positions along the respective guide pin 272. The first set of protrusions 288 and the second set of protrusions 290 form two different axial positions for moving the bowtie filter assembly 166 in the lateral direction 184 (one position of the bowtie filter 170 in the scanning plane and one position of the bowtie filter 172 outside the scanning plane). In the unlocked position, the first set of protrusions 288 and / or the second set of protrusions 290 pass through the housing 274, allowing the bowtie filter assembly 166 to move in the lateral direction 184. In the locked position, the first set of protrusions 288 or the second set of protrusions 290 engages with the wall defining the housing 274 to prevent movement of the bowtie filter assembly 166 in the lateral direction 184.

[0079] The adjustment mechanism 180 includes a frame 292 that is part of and extends from the filter mounting plate 262. The frame 292 allows the bowtie filter assembly 166 to move in a lateral direction 182, independent of movement in the transverse direction 184. The frame 292 moves parallel to... Figures 7 to 10 The second wall 76 and the third wall 78 of the collimator housing 162 extend in the direction 184. The frame 292 includes a slot 294.

[0080] The adjustment mechanism 180 includes an adjustment screw 208, which adjusts the bowtie filter assembly 166 in... Figures 7 to 10The adjustment screw 208 allows for lateral movement 182 within the collimator housing 62. The adjustment screw 208 adjusts the bowtie filter assembly 166 so that the bowtie filter 170 is isocenter of the X-ray beam. A portion of the adjustment screw 208 extends through a nut 210 (e.g., a locking nut) on the outside of the collimator housing 62 and enters the internal space 110 of the collimator housing 62 (via an opening in the second wall 76). Within the collimator housing 62, this portion of the adjustment screw 208 extends through a slot 294 and is secured to the frame 292 via a fastener 212 (e.g., a nut). Rotation of the adjustment screw 208 moves the bowtie filter assembly 166 laterally 182. Each end of the slot 294 serves as a constraint on the lateral movement 184 of the bowtie filter assembly 166. Once adjustment is complete, the locking nut 210 can be used to secure the position of the bowtie filter assembly 166. Actuation of the adjustment screw 208 can be mechanical. In some embodiments, actuation of the adjusting screw 208 may be achieved via a motorized actuator coupled to the adjusting screw 208 (in response to a signal from...). Figure 1 The control signal of the collimator controller 29's processing circuit is automatically processed. The rotation of the adjusting screw 208 circumferentially toward the fourth wall 80 causes the bow filter assembly 166 to rotate laterally toward the fourth wall 80. Figures 7 to 10 The movement of the second wall 76 of the collimator housing 62, while the rotation of the adjusting screw 208 away from the fourth wall 80 in the circumferential direction, causes the bow filter assembly 166 to move toward the third wall 78 in the lateral direction 182.

[0081] Figure 34 This is a perspective view of the assembled front collimator 13. The collimator 13 includes the additively manufactured collimator housing 62, the additively manufactured orifice carrier plate 64, and the additively manufactured motor mounting plate 66. Additionally, the collimator 13 includes a built-in alignment mechanism 260, an adjustment mechanism 180, and a motor 222, which is coupled to the motor mounting plate 66 and configured to move the orifice carrier plate 64 (via actuators and track guides).

[0082] Figure 35 This is a flowchart of method 296 for centering a bowtie filter relative to the center of an X-ray beam. Method 296 can utilize... Figure 1The method is performed by one or more components of the CT system 10 (e.g., computer 36, collimator controller 29, etc.). Method 296 includes obtaining air scan data with a bow filter (e.g., as part of a bow filter assembly) that is moved out of the field of view or out of the scan plane before air scanning within the pre-collimator (box 298). The bow filter may be moved out of the scan plane using one of the adjustment mechanisms described above for moving the bow filter assembly in the lateral direction. The bow filter is not removed from the collimator during box 298. Method 296 also includes obtaining alignment scan data (e.g., via a centrosome filter scan) after the bow filter has been moved into the scan plane in the lateral direction (via the same adjustment mechanism) (box 300). Method 296 also includes calculating or determining (e.g., via processing circuitry) an offset value or distance from the center of the beamline path based on the air scan data and the alignment scan data (box 302). Method 296 also includes comparing the offset value with an acceptable or desired range of the center position of the bow filter (e.g., where the center of the bow filter coincides with isocentric alignment) (box 304). If the offset value is outside the acceptable range, method 296 includes calculating (e.g., via processing circuitry) a value or distance (box 306) to move the bowtie filter laterally to achieve the desired center position (e.g., within the acceptable range). Method 296 also includes moving the bowtie filter laterally by the calculated value or distance (e.g., a fraction of a millimeter) using one of the adjustment mechanisms described above (e.g., adjustment screw 208) (box 308). The lateral adjustment of the bowtie filter can be performed automatically based on a control signal (e.g., from collimator controller 29) sent to an actuator coupled to the adjustment mechanism (e.g., adjustment screw 208) to move the bowtie filter laterally. Method 296 then repeats boxes 298-304. If the offset value is within the acceptable range, method 296 ends (box 310).

[0083] The technical advantages of the embodiments disclosed in this invention include providing a built-in alignment mechanism disposed within the front collimator for precise and easy adjustment of the collimator during system alignment. Specifically, the built-in alignment mechanism enables adjustment of the bowtie filter in both lateral and transverse directions (e.g., for alignment relative to the X-ray beam path to provide excellent image quality). The configuration of the built-in alignment mechanism also allows adjustment of the bowtie filter from outside the collimator housing (e.g., via an actuator mechanism) without having to remove or detach the sub-component (e.g., the bowtie filter) from the collimator during system alignment. Furthermore, the built-in alignment mechanism is configured for use with different types of bowtie filters and can be extended for use with different imaging platforms.

[0084] Referring to the technology presented herein and protected by the claims, and applying it to physical objects and concrete examples of practical nature, which explicitly improves the present art, it is therefore not abstract, intangible, or purely theoretical. Furthermore, if any claim appended to the end of this specification contains one or more elements designated as “means for [performing]…” or “steps for [performing]…”, such elements are intended to be interpreted pursuant to Section 35, Section 112(f) of the USC. However, for any claim containing elements designated in any other manner, such elements are not intended to be interpreted pursuant to Section 35, Section 112(f) of the USC.

[0085] This written description uses examples to disclose the subject matter, including best practices, and also enables those skilled in the art to practice the subject matter, including making and using any apparatus or system and performing any included methods. The patent scope of this subject matter is defined by the claims and may include other examples that would occur to those skilled in the art. Such other examples are intended to fall within the scope of the claims if they have structural elements that are not indistinguishable from the literal language of the claims, or if they include equivalent structural elements that have minor differences from the literal language of the claims.

Claims

1. A precollimator for a computed tomography (CT) imaging system, the precollimator comprising: Collimator housing, the collimator housing including a plurality of walls, wherein the plurality of walls include a first wall, a second wall and a third wall laterally connected to the first wall, and a fourth wall extending between the second wall and the third wall adjacent to the first wall, the first wall being configured to face the X-ray source when the front collimator is coupled to the CT imaging system; A bow filter assembly, wherein the bow filter assembly is disposed within the collimator housing and includes a bow filter; and An adjustment mechanism is configured to move the bowtie filter assembly laterally between the second and third walls within the collimator housing, and to move the bowtie filter assembly laterally toward and away from the fourth wall. The adjustment mechanism includes: a frame disposed within the collimator housing and connected to the bowtie filter assembly; an adjustment screw connected to the frame and configured to adjust movement of the bowtie filter assembly in the lateral direction; and a locking pin connected to the frame and configured to adjust movement of the bowtie filter assembly in the transverse direction. The frame includes: a first opening for receiving the locking pin when the bow filter assembly is moved out of the scanning plane in the lateral direction; and a second opening for receiving the locking pin when the bow filter assembly is moved into the scanning plane in the lateral direction.

2. The precollimator according to claim 1, wherein the movement of the bowtie filter assembly along the lateral direction is independent of the movement of the bowtie filter assembly along the transverse direction.

3. The collimator of claim 1, wherein the frame includes a slot through which the adjusting screw extends, wherein the slot is configured to retain the adjusting screw extending through the slot as the bow filter assembly moves in the lateral direction.

4. The precollimator of claim 1, wherein the adjustment mechanism is configured to be operated from the outside of the collimator housing to move the bowtie filter assembly within the collimator housing in the lateral and transverse directions.

5. The precollimator of claim 1, wherein the precollimator includes a motorized actuator coupled to the adjustment mechanism, and the motorized actuator is configured to actuate the adjustment mechanism in response to a control signal from a processor to move the bowtie filter assembly in the lateral direction, thereby centering the bowtie filter for an X-ray beam emitted by the X-ray source.

6. The precollimator of claim 1, wherein the bowtie filter assembly includes a filter mounting plate and a cover to partially enclose the bowtie filter within the bowtie filter assembly.

7. The front collimator according to claim 6, wherein radiation shielding material is provided on the respective surfaces of both the filter mounting plate and the cover facing the bow filter.

8. The precollimator of claim 6, wherein the filter mounting plate and the cover are configured to partially enclose different types of bow filters within them.

9. A precollimator for a computed tomography (CT) imaging system, the precollimator comprising: Collimator housing; A bow filter assembly, wherein the bow filter assembly is disposed within the collimator housing and includes a bow filter; and An adjustment mechanism is configured to move the bowtie filter assembly within the collimator housing along a first direction and a second direction, wherein the movement of the bowtie filter assembly along the first direction is independent of the movement of the bowtie filter assembly along the second direction, and wherein the first direction and the second direction are orthogonal to each other. The adjustment mechanism includes: a frame disposed within the collimator housing and connected to the bowtie filter assembly; an adjustment screw connected to the frame and configured to adjust movement of the bowtie filter assembly along a first direction; and a locking pin connected to the frame and configured to adjust movement of the bowtie filter assembly along a second direction. The frame includes: a first opening for receiving the locking pin when the bow filter assembly is moved out of the scanning plane along the second direction; and a second opening for receiving the locking pin when the bow filter assembly is moved into the scanning plane along the second direction.

10. The collimator of claim 9, wherein the collimator housing includes a first wall configured to face an X-ray source when the collimator is coupled to the CT imaging system, and wherein the first direction and the second direction are orthogonal to each other along planes parallel within the first wall.

11. The collimator of claim 9, wherein the collimator housing includes a plurality of walls, wherein the plurality of walls includes a first wall and a second and a third wall laterally connected to the first wall, the first wall being configured to face an X-ray source when the collimator is coupled to the CT imaging system, and wherein the adjustment mechanism is configured to move the bowtie filter assembly along the first direction between the second wall and the third wall.

12. The precollimator of claim 11, wherein the plurality of walls includes a fourth wall extending between the second wall and the third wall adjacent to the first wall, and the adjustment mechanism is configured to move the bowtie filter assembly toward and away from the fourth wall along the second direction.

13. The collimator of claim 9, wherein the adjustment mechanism is configured to be operated from the outside of the collimator housing to move the bowtie filter assembly within the collimator housing along the first and second directions.

14. The precollimator of claim 9, wherein the bowtie filter assembly includes a filter mounting plate and a cover to partially enclose the bowtie filter within the bowtie filter assembly.

15. A method for performing collimator bowtie filter alignment, the method comprising: Air scan data acquired via air scan using a computed tomography (CT) imaging system is obtained at the processor, wherein a bowtie filter is moved outside the field of view of the X-ray beam emitted by the X-ray source of the CT imaging system prior to the air scan to obtain the air scan data, wherein the bowtie filter is disposed within a bowtie filter assembly disposed within a collimator housing, and wherein the bowtie filter assembly is configured to move within the collimator housing along a first direction and a second direction via an adjustment mechanism, the first direction being orthogonal to the second direction, and wherein the adjustment mechanism includes a frame, the frame being disposed The system comprises: an adjusting screw connected to the frame and configured to adjust movement of the bowtie filter assembly along the first direction; and a locking pin connected to the frame and configured to adjust movement of the bowtie filter assembly along the second direction, wherein the frame includes: a first opening for receiving the locking pin when the bowtie filter assembly is moved out of the scanning plane along the second direction; and a second opening for receiving the locking pin when the bowtie filter assembly is moved into the scanning plane along the second direction. Alignment data acquired via air scanning using the CT imaging system is obtained at the processor, wherein the bowtie filter is moved into the scanning plane along the second direction prior to the alignment scan to obtain the air scan data; The processor calculates the offset distance between the bow filter and the beamline path of the X-ray beam; The processor compares the offset distance with an acceptable range for the desired center position of the bowtie filter within the X-ray beam; When the offset distance is outside the acceptable range, the processor calculates and uses the adjustment mechanism to move the bowtie filter along the second direction to center the bowtie filter within the X-ray beam; and In response to a control signal from the processor, the bow filter is moved by the distance along the second direction.

16. The method of claim 15, wherein the movement of the bowtie filter assembly along the first direction is independent of the movement of the bowtie filter assembly along the second direction.

17. A computed tomography (CT) imaging system, comprising a precollimator, wherein the precollimator includes: Collimator housing; A bow filter assembly, wherein the bow filter assembly is disposed within the collimator housing and includes a bow filter; and An adjustment mechanism is configured to move the bowtie filter assembly within the collimator housing along a first direction and a second direction, wherein the movement of the bowtie filter assembly along the first direction is independent of the movement of the bowtie filter assembly along the second direction, and wherein the first direction and the second direction are orthogonal to each other. The adjustment mechanism includes: a frame disposed within the collimator housing and connected to the bowtie filter assembly; an adjustment screw connected to the frame and configured to adjust movement of the bowtie filter assembly along a first direction; and a locking pin connected to the frame and configured to adjust movement of the bowtie filter assembly along a second direction. The frame includes: a first opening for receiving the locking pin when the bow filter assembly is moved out of the scanning plane along the second direction; and a second opening for receiving the locking pin when the bow filter assembly is moved into the scanning plane along the second direction.

Images