Patent Description:
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).

<NPL>" describes improvements in the available flux at neutron sources which make it increasingly feasible to obtain refineable neutron diffraction data from samples smaller than <NUM><NUM>. The signal is typically too weak to introduce any further sample environment in the <NUM>-<NUM> 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.

<CIT> 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.

<CIT> 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.

<CIT> 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.

<CIT> 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.

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.

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 <NUM>.

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:.

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.

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).

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.

With the foregoing discussion in mind, <FIG> illustrates an embodiment of an imaging system <NUM> 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 <NUM> 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 <NUM> includes one or more X-ray sources <NUM>, 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.

In certain implementations, the source <NUM> may be positioned proximate to a collimator <NUM> used to define the size and shape of the one or more X-ray beams <NUM> that pass into a region in which a subject <NUM> (e.g., a patient) or object of interest is positioned. The subject <NUM> attenuates at least a portion of the X-rays. Resulting attenuated X-rays <NUM> impact a detector array <NUM> 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 <NUM>. Electrical signals are acquired and processed to generate one or more scan datasets.

A system controller <NUM> commands operation of the imaging system <NUM> to execute examination and/or calibration protocols and to process the acquired data. With respect to the X-ray source <NUM>, the system controller <NUM> furnishes power, focal spot location, control signals and so forth, for the X-ray examination sequences. The detector <NUM> is coupled to the system controller <NUM>, which commands acquisition of the signals generated by the detector <NUM>. In addition, the system controller <NUM>, via a motor controller <NUM>, may control operation of a linear positioning subsystem <NUM> and/or a rotational subsystem <NUM> used to move components of the imaging system <NUM> and/or the subject <NUM>. The system controller <NUM> 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 <NUM> to operate the imaging system <NUM>, including the X-ray source <NUM>, and to process the data acquired by the detector <NUM> in accordance with the steps and processes discussed herein. In one embodiment, the system controller <NUM> may be implemented as all or part of a processor-based system such as a general purpose or application-specific computer system.

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

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

The computer <NUM> may also be adapted to control features enabled by the system controller <NUM> (i.e., scanning operations and data acquisition), such as in response to commands and scanning parameters provided by an operator via an operator workstation <NUM>. The system <NUM> may also include a display <NUM> coupled to the operator workstation <NUM> that allows the operator to view relevant system data, imaging parameters, raw imaging data, reconstructed data, and so forth. Additionally, the system <NUM> may include a printer <NUM> coupled to the operator workstation <NUM> and configured to print any desired measurement results. The display <NUM> and the printer <NUM> may also be connected to the computer <NUM> directly or via the operator workstation <NUM>. Further, the operator workstation <NUM> may include or be coupled to a picture archiving and communications system (PACS) <NUM>. PACS <NUM> may be coupled to a remote system <NUM>, 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.

<FIG> is a flow chart for an embodiment of a method <NUM> for producing a coated 3D printed part. The method <NUM> includes additively manufacturing or providing an additively manufacturing 3D printed part (block <NUM>). 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 <NUM>). 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.).

The method <NUM> also includes cleaning the printed part (block <NUM>). 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.

The method <NUM> also includes preparing a coating (block <NUM>). 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, <NUM>-part reactive polymers, or <NUM>-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.

The method <NUM> further includes applying the coating to the printed part (block <NUM>). 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.

<FIG> is a schematic cross-sectional view of a portion of a coated 3D printed part. As depicted, <FIG> includes a 3D printed part <NUM> and a coating <NUM> disposed over the surfaces of the 3D printed part <NUM>. As noted above, the 3D printed part <NUM> is a component of an imaging system that includes metal particles. For example, the printed part <NUM> may be any component of an imaging system (e.g., imaging system <NUM>). For example, the printed part <NUM> may be a frame, electronics, collimator, or other component of the imaging system. As depicted in <FIG>, the printed part <NUM> is a two-dimensional (2D) collimator. In the case of the coating <NUM> for the collimator, the coating <NUM> 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 <NUM> (e.g., of a few micrometers) is such that it does not influence the geometry of the printed part <NUM> nor cause the printed part <NUM> to exceed its engineering tolerance.

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

Certain printed parts, such as a collimator are very fragile due to most walls being very thin (e.g., between approximately <NUM> micrometers and <NUM> 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 <NUM> 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 <NUM> millimeters (mm) for the length, <NUM> for the width, and <NUM> for the thickness) under a tensile strength test may have a maximum load (N) of <NUM>. However, the same bar coated in a first epoxy-based coating and a second epoxy-based coating has maximum loads of <NUM> and <NUM>, respectively. Thus, the coating increases the mechanical strength of the printed part (such as a collimator).

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