Use of a coating to reduce the release of metal particles from a three-dimensional, additively manufactured component of an imaging system

Description

BACKGROUND

[0001] The subject matter disclosed herein relates to imaging systems, and more particularly, to mitigating metal particle leakage from additive three-dimensional (3D) printed parts of the imaging systems.

[0002] Some components of an imaging system (e.g., computed tomography (CT) imaging system) may be printed or additively manufactured out of one or more materials. Some of these materials may include metal (e.g., metal powder). Loose or weakly attached powder particles (e.g., metal powder particles) may leach out from the 3D printed parts due to the nature of the additive manufacturing process. These leached out metal particles may cause image defects or the malfunction of other imaging components due to the rotating nature of a CT scanner. Typical cleaning techniques (e.g., air blowing, solvent or water rinse, ultrasound cleaning, etc.) may not be effective at completely removing these loose particles even if the cleaning is extensive (or in some cases may further promote this leakage). For example, an imaging system may include one or more collimator modules (e.g., additively manufactured collimator modules). The collimator modules may be utilized under a wide range of loads (e.g., in a high speed spin or slow rotation) and subjected to vibrations (e.g., from scanners) that cause loose particles to move around that can impact clinical images (e.g., due to density of the particles) or cause damage to other imaging components (e.g., by entering within precision ceramic bearings).

[0003] RIDLEY CHRISTOPHER J ET AL, "A novel compact three-dimensional laser-sintered collimator for neutron scattering" describes improvements in the available flux at neutron sources which make it increasingly feasible to obtain refineable neutron diffraction data from samples smaller than 1 mm 3< . The signal is typically too weak to introduce any further sample environment in the 30-50 mm diameter surrounding the sample (such as the walls of a pressure cell) due to the high ratio of background to sample signal, such that even longer count times fail to reveal reflections from the sample. Many neutron instruments incorporate collimators to reduce parasitic scattering from the instrument and from any surrounding material and larger pieces of sample environment, such as cryostats. However, conventional collimation is limited in the volume it can focus on due to difficulties in producing tightly spaced neutron-absorbing foils close to the sample and in integrating this into neutron instruments. The authors present the design of a compact 3D rapid-prototyped (or "printed") collimator which reduces these limitations and is shown to improve the ratio of signal to background, opening up the feasibility of using additional sample environment for neutron diffraction from small sample volumes.

[0004] US6459771B1 describes a method for fabricating precision x-ray collimators including precision focusing x-ray collimators. Fabricating precision x-ray collimators includes the steps of using a substrate that is electrically conductive or coating a substrate with a layer of electrically conductive material, such as a metal. Then the substrate is coated with layer of x-ray resist. An intense radiation source, such as a synchrotron radiation source, is utilized for exposing the layer of x-ray resist with a pattern of x-ray. The pattern delineates a grid of apertures to collimate the x-rays. Exposed parts of the x-ray resist are removed. Regions of the removed x-ray resist are electroplated. Then remaining resist is optionally removed from the substrate. When exposing the layer of x-ray resist with a pattern of x-ray for non-focusing collimators, the substrate is maintained perpendicular to impinging x-rays from the synchrotron radiation source; and the substrate is scanned vertically. For precision focusing x-ray collimators, the substrate is scanned vertically in the z-direction while varying the angle of inclination of the substrate in a controlled way as a function of the position of the z-direction during the scan.

[0005] US4853550A describes a device for irradiating an object, including a source mount, a source disposed on the source mount for generating thermal neutron rays, a moderator surrounding the source, a collimator having a ray inlet side with an inner surface and at least one funnel-shaped collimator duct for the neutron rays opening toward an object, a neutron-permeable wall separating the source mount from the ray inlet side of the collimator defining a space between the wall and the ray inlet side with an inner peripheral surface of the space, and a plastic plating disposed on the inner peripheral surface of the space and on the inner surface of the ray inlet side defining an opening of the at least one collimator duct free of the plastic plating.

[0006] CN203422938U describes providing a radial collimator as an optical part of a neutron scattering spectrometer. The collimator comprises absorption separating sheets, an aluminum frame, a steel wedged pad, and an outer frame, the absorption separating sheets are in a sector distribution, and form a group of constraint neutron channels in a sector distribution, namely, the extending lines of absorption slits are gathered at one point. The radial collimator is placed in front of a position sensitive detector, and constrains diffraction neutrons going through a sample.

[0007] US2018230584A1 describes manufactured articles, and methods of manufacturing enhanced surface smoothed components and articles. More particularly, surface smoothed components and articles, such as combustor components of turbine engines, having surface treatment conferring reduced roughness for enhanced performance and reduced wear related reduction in part life are described.BRIEF DESCRIPTION

[0008] Certain embodiments are summarized below. These embodiments are not intended to limit the scope of the claimed subject matter. While various embodiments are described to facilitate understanding, the invention to which this European patent relates is defined by the claims and the scope of protection is defined by these claims.

[0009] In one implementation, a use of a coating for mitigating metal particle leakage from a three-dimensional additively manufactured component of an imaging system is disclosed, as set out in claim 1.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] These and other features and aspects of embodiments of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: FIG. 1 is a block diagram representation of a CT system, in accordance with aspects of the present disclosure; FIG. 2 is a flow chart for an embodiment of a method for producing a coated 3D printed part, in accordance with aspects of the present disclosure; FIG. 3 is a schematic cross-sectional view of an embodiment of a portion of a coated 3D printed part (e.g., coated collimator), in accordance with aspects of the present disclosure; and FIG. 4 is a cross-sectional view of the coated 3D printed part of FIG. 3, taken within line 4-4, in accordance with aspects of the present disclosure. DETAILED DESCRIPTION

[0011] One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0012] When introducing elements of various embodiments of the present invention, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of the elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements. Furthermore, any numerical examples in the following discussion are intended to be nonlimiting, and thus additional numerical values, ranges, and percentages are within the scope of the disclosed embodiments.

[0013] While aspects of the following discussion may be provided in the context of medical imaging, it should be appreciated that the present techniques are not limited to such medical contexts. Indeed, the provision of examples and explanations in such a medical context is only to facilitate explanation by providing instances of real-world implementations and applications. However, the present approaches may also be utilized in other contexts, such as imaging (e.g., in industrial use) in non-destructive inspection of manufactured parts or goods (i.e., quality control or quality review applications), and / or the non-invasive inspection of packages, boxes, luggage, and so forth (i.e., security or screening applications).

[0014] The present disclosure provides for systems and methods for mitigating metal particle leakage from three-dimensional (3D) printed or additively manufactured parts (e.g., of an imaging system). In particular, a coating is applied to the printed part to avoid the leakage of metal particles. In the context of medical imaging, avoiding the leakage of metal particles from the printed part may avoid image defects and / or the malfunction of other imaging components. In certain embodiments, the coating may be fine-tuned (e.g., include one or more materials) to improve or alter a characteristic or function of the printed part (e.g., mechanical strength, thermal conductivity, surface finish, etc.). The coating may mitigate the need for extensive cleaning, thus, reducing the time to finish manufacturing the printed part, while avoiding both producing particle residues and damage to the printed part.

[0015] With the foregoing discussion in mind, FIG. 1 illustrates an embodiment of an imaging system 10 for acquiring and processing image data that may utilize 3D additively manufactured or printed parts in accordance with aspects of the present disclosure. Although the following embodiments are discussed in terms of the computed tomography (CT) imaging system, the embodiments may also be utilized with other imaging systems (e.g., X-ray, PET, CT / PET, SPECT, nuclear CT, etc.). In the illustrated embodiment, system 10 is a computed tomography (CT) system designed to acquire X-ray projection data, to reconstruct the projection data into a tomographic image, and to process the image data for display and analysis. The CT imaging system 10 includes one or more X-ray sources 12, such as one or more X-ray tubes or solid-state emission structures which allow X-ray generation at one or more locations and / or one or more energy spectra during an imaging session.

[0016] In certain implementations, the source 12 may be positioned proximate to a collimator 22 used to define the size and shape of the one or more X-ray beams 20 that pass into a region in which a subject 24 (e.g., a patient) or object of interest is positioned. The subject 24 attenuates at least a portion of the X-rays. Resulting attenuated X-rays 26 impact a detector array 28 formed by a plurality of detector elements. Each detector element produces an electrical signal that represents the intensity of the X-ray beam incident at the position of the detector element when the beam strikes the detector 28. Electrical signals are acquired and processed to generate one or more scan datasets.

[0017] A system controller 30 commands operation of the imaging system 10 to execute examination and / or calibration protocols and to process the acquired data. With respect to the X-ray source 12, the system controller 30 furnishes power, focal spot location, control signals and so forth, for the X-ray examination sequences. The detector 28 is coupled to the system controller 30, which commands acquisition of the signals generated by the detector 28. In addition, the system controller 30, via a motor controller 36, may control operation of a linear positioning subsystem 32 and / or a rotational subsystem 34 used to move components of the imaging system 10 and / or the subject 24. The system controller 30 may include signal processing circuitry and associated memory circuitry. In such embodiments, the memory circuitry may store programs, routines, and / or encoded algorithms executed by the system controller 30 to operate the imaging system 10, including the X-ray source 12, and to process the data acquired by the detector 28 in accordance with the steps and processes discussed herein. In one embodiment, the system controller 30 may be implemented as all or part of a processor-based system such as a general purpose or application-specific computer system.

[0018] The source 12 may be controlled by an X-ray controller 38 contained within the system controller 30. The X-ray controller 38 may be configured to provide power and timing signals to the source 12. In addition, in some embodiments the X-ray controller 38 may be configured to selectively activate the source 12 such that tubes or emitters at different locations within the system 10 may be operated in synchrony with one another or independent of one another.

[0019] The system controller 30 may include a data acquisition system (DAS) 40. The DAS 40 receives data collected by readout electronics of the detector 28, such as sampled analog signals from the detector 28. The DAS 40 may then convert the data to digital signals for subsequent processing by a processor-based system, such as a computer 42. In other embodiments, the detector 28 may convert the sampled analog signals to digital signals prior to transmission to the data acquisition system 40. The computer may include processing circuitry 44 (e.g., image processing circuitry). The computer 42 may include or communicate with one or more non-transitory memory devices 46 that can store data processed by the computer 42, data to be processed by the computer 42, or instructions to be executed by a processor (e.g., processing circuitry 44) of the computer 42. For example, the processing circuitry 44 of the computer 42 may execute one or more sets of instructions stored on the memory 46, which may be a memory of the computer 42, a memory of the processor, firmware, or a similar instantiation.

[0020] The computer 42 may also be adapted to control features enabled by the system controller 30 (i.e., scanning operations and data acquisition), such as in response to commands and scanning parameters provided by an operator via an operator workstation 48. The system 10 may also include a display 50 coupled to the operator workstation 48 that allows the operator to view relevant system data, imaging parameters, raw imaging data, reconstructed data, and so forth. Additionally, the system 10 may include a printer 52 coupled to the operator workstation 48 and configured to print any desired measurement results. The display 50 and the printer 52 may also be connected to the computer 42 directly or via the operator workstation 48. Further, the operator workstation 48 may include or be coupled to a picture archiving and communications system (PACS) 54. PACS 54 may be coupled to a remote system 56, radiology department information system (RIS), hospital information system (HIS) or to an internal or external network, so that others at different locations can gain access to the image data.

[0021] FIG. 2 is a flow chart for an embodiment of a method 58 for producing a coated 3D printed part. The method 58 includes additively manufacturing or providing an additively manufacturing 3D printed part (block 60). The printed part is made of one or more materials comprising a metal. These materials may include one or more different metals (e.g., metal powders) depending on the part. According to the invention to which this European patent relates, the part is an additively manufactured component of an imaging system (e.g., imaging system 10). For example, the part may be a frame, circuitry, a collimator, or any other component that can be additively manufactured. The printed part may be additively manufactured via any additive manufacturing technique (e.g., laser powder bed fusion, photopolymerization, material jetting, binder jetting, material extrusion, sheet lamination, direct energy deposition, etc.).

[0022] The method 58 also includes cleaning the printed part (block 62). Typically, in the absence of a coating, printed parts undergo extensive cleaning repeatedly that is both time consuming and leaves particle residues (even after multiple days of cleaning). In addition, the extensive cleaning may physically damage the printed part. Extensive cleaning may include compressed air cleaning and blowing, solvent- or water-based cleaning, ultrasonic cleaning, or the addition of filtration units. With the coating, less cleaning of the printed parts may be needed compared to printed parts without the coating. For example, passive cleaning may be utilized before the application of the coating. Passive cleaning may include mechanical vibration or de-powdering.

[0023] The method 58 also includes preparing a coating (block 64). Preparing the coating may be as simple as getting it ready (e.g., mixing, if needed) for application depending on the composition of the coating. For example, the coating may include a mixture of materials. According to the invention to which this European patent relates, the coating comprises a polymer. The coating may be made of organic polymers or polymer composites. In certain embodiments, the coating may be made of non-reactive polymers, 1-part reactive polymers, or 2-part reactive polymers. In certain embodiments, the coating may be made of thermosetting polymers or thermoplastic polymers. In certain embodiments, the coating may be made of one or more of epoxies, polyurethanes, polyacrylics, cyanoacrylates, silicones, polyolefins, polyvinyl alcohol, rubbers, polyvinyl chloride, phenol formaldehyde, nylon, and polyacrylonitrile. In certain embodiments, the coating may be made of pure polymers or polymer blends. In certain embodiments, the coating may be made of a polymer composite that may include inorganic fillers, ceramic precursors, or fine metal particles. In certain embodiments, the coating may be fined tuned (e.g., include one or more materials) to improve or alter a characteristic or function of the printed part (e.g., mechanical strength, thermal conductivity, surface finish, etc.) depending on the application. For example, the coating may include a heavy metal powder (e.g., tungsten) configured to increase radiation shielding.

[0024] The method 58 further includes applying the coating to the printed part (block 66). For example, applying the coating may include immersing the printed part within the coating, spraying the coating on the printed part, brush coating the coating, or another technique. In certain embodiments, a coating with monomers or oligomers with crosslinkers may be coated to the surfaces of the printed part and then chemical crosslinking performed. In certain embodiments, the surfaces of the printed part may be coated with a polymer solution and then the polymer solution may be solidified via evaporation or cooling down of melted polymers. Typically, the coating may be a liquid that penetrates through the surfaces of the printed part to anywhere that the metal particles have the potential to leak out to and prevent the movement of the particles after curing or solidification. The coating may be applied separately to individual printed parts or applied to multiple printed parts at the same time.

[0025] FIG. 3 is a schematic cross-sectional view of a portion of a coated 3D printed part. As depicted, FIG. 3 includes a 3D printed part 68 and a coating 70 disposed over the surfaces of the 3D printed part 68. As noted above, the 3D printed part 68 is a component of an imaging system that includes metal particles. For example, the printed part 68 may be any component of an imaging system (e.g., imaging system 10). For example, the printed part 68 may be a frame, electronics, collimator, or other component of the imaging system. As depicted in FIG. 3, the printed part 68 is a two-dimensional (2D) collimator. In the case of the coating 70 for the collimator, the coating 70 is almost transparent to radiation (i.e., the coating does not affect the functionality of the collimator with regard to collimation. A thickness of the coating 70 (e.g., of a few micrometers) is such that it does not influence the geometry of the printed part 68 nor cause the printed part 68 to exceed its engineering tolerance.

[0026] As mentioned above, the coating 70 may be fine-tuned (e.g., include one or more materials) to improve or alter a characteristic or function of the printed part 68 (e.g., mechanical strength, thermal conductivity, surface finish, etc.) depending on the application. FIG. 4 is a cross-sectional view of the coated 3d printed part 68 of FIG. 3, taken within line 4-4. As depicted, the coating 70 includes inorganic fillers, ceramic precursors, or fine metal particles 72. In certain embodiments, the coating 70 includes a heavy metal powder (e.g., tungsten) to increase radiation shielding when the printed part 68 is a collimator as in FIGS. 3 and 4.

[0027] Certain printed parts, such as a collimator are very fragile due to most walls being very thin (e.g., between approximately 30 micrometers and 300 micrometers). In the case of collimator, it is subject to a wide range of loads (e.g., from a high-speed spin to a slow rotation) that (in the absence of a coating) cause loose metal particles to leak from the collimator. The addition of the coating 70 to the collimator increases the collimator's mechanical strength and toughness. For example, a printed tungsten tensile bar (e.g., having the dimensions of approximately 250 millimeters (mm) for the length, 23.7 mm for the width, and 1.82 mm for the thickness) under a tensile strength test may have a maximum load (N) of 2753. However, the same bar coated in a first epoxy-based coating and a second epoxy-based coating has maximum loads of 3613 and 2954, respectively. Thus, the coating increases the mechanical strength of the printed part (such as a collimator).

[0028] As discussed herein, technical effects of the disclosed subject matter include providing a coating on an additively manufactured or printed 3D component of an imaging system (e.g., a collimator). The coating applied to the printed part minimizes or avoids the leakage of metal particles from the printed part. In the context of medical imaging, avoiding the leakage of metal particles from the printed part may avoid image defects and / or the malfunction of other imaging components. In certain embodiments, the coating may be fine-tuned (e.g., include one or more materials) to improve or alter a characteristic or function of the printed part (e.g., mechanical strength, thermal conductivity, surface finish, etc.). The coating may mitigate the need for extensive cleaning, thus, reducing the time to finish manufacturing the printed part and avoiding both producing particle residues and damage to the printed part during the cleaning.

Claims

1. Use of a coating (70) for mitigating metal particle leakage from a three-dimensional additively manufactured component (68) of an imaging system (10), wherein the component (68) is manufactured from one or more materials, the one or more materials comprising a metal, characterized in that said coating (70) comprises a polymer.

2. The use of claim 1, wherein the additively manufactured component (68) comprises a collimator (22).

3. The use of any preceding claim, wherein the imaging system (10) comprises a computed tomography imaging system.

4. The use of claim 1, wherein the coating (70) comprises a two-part reactive polymer, a one-part reactive polymer, or a non-reactive polymer.

5. The use of claim 1, wherein the coating (70) is applied by coating the coating (70) having monomers or oligomers with crosslinkers on the additively manufactured component (68) and performing chemical crosslinking.

6. The use of claim 1, wherein the coating (70) is applied by coating the coating (70) having a polymer solution on the additively manufactured component (68) and solidifying the polymer solution via evaporation or cooling down of melted polymers.

7. The use of claim 1, wherein the coating (70) comprises thermosetting polymers or thermoplastic polymers.

8. The use of claim 7, wherein the coating (70) comprises one or more of epoxies, polyurethanes, polyacrylics, cyanoacrylates, silicones, polyolefins, polyvinyl alcohol, rubbers, polyvinyl chloride, phenol formaldehyde, nylon, and polyacrylonitrile.

9. The use of claim 1, wherein the coating (70) comprises pure polymers or polymer blends.

10. The use of claim 1, wherein the coating (70) comprises a polymer composite with inorganic fillers, ceramic precursors, or fine metal particles.

11. The use of claim 1, wherein the additively manufactured component (68) having the coating (70) is passively cleaned, wherein the passive cleaning comprises less cleaning than cleaning the additively manufactured component (68) without the coating (70).

12. The use of claim 1, wherein the coating (70) is configured to increase a mechanical strength of the additively manufactured component (68) compared to the additively manufactured component without the coating (70).

13. The use of claim 1, wherein the coating (70) comprises a heavy metal powder configured to increase radiation shielding.