摘要:
The present invention is, in one aspect, an imaging system having a detector that has multiple detector cells extending along a z-axis, the detector being configured to collect multiple slices of data; and a scalable data acquisition system configured to convert signals from the detector to digital form, the scalable data acquisition system having a plurality of converter boards each with a plurality of channels, the channels and detector cells having an interweaved coupling to reduce susceptibility to band artifact.
摘要:
The present invention, in one form, is a system which, in one embodiment, adjusts the x-ray source current to reduce image noise to better accommodate different scanning parameters. Specifically, in one embodiment, the x-ray source current is adjusted as a function of image slice thickness, scan rotation time, collimation mode, table speed, scan mode, and filtration mode. Particularly, a function is stored in a CT system computer to determine an x-ray source current adjustment factor so that the appropriate x-ray source current is supplied to the x-ray source for the determined parameters. After adjusting the x-ray source current, an object is scanned.
摘要:
Scalable multislice systems which, in one embodiment, includes a scalable multislice detector, a scalable data acquisition system (SDAS), scalable scan management, control, and image reconstruction processes, and a user interface, are described. More specifically, the user interface is implemented in a host computer for defining the configuration of the imaging system. Particularly, after selection of each scan parameter, the user interface displays the available scan parameter values for the remaining parameters so that the scan objectives are met. More specifically, after selection of each scan parameter, the user interface updates the remaining scan parameters, including prospective and retrospective image thicknesses.
摘要:
A scalable multislice system which, in one embodiment, includes a scalable multi-slice detector, a scalable data acquisition system (SDAS), scalable scan management, control, and image reconstruction processes, and scalable image display and analysis, is described. In the axial multi-slice scan mode, multiple rows of scan data can be processed before image reconstruction, and the data can be used to produce either multiple thin slices or a reduced number of thicker slices with reduced image artifact. In addition, images with thicker slice thicknesses can be later reconstructed retrospectively into thinner slices of images based on clinical diagnosis needs. As a result, the number of unwanted images for viewing, filming, and archiving is reduced. In addition, high z-axis resolution images can be later reconstructed for patient diagnosis. In the helical multi-slice scan mode, multiple combinations of patient table speed and x-ray beam and detector collimations, enable generation of images having different z-axis resolution can be produced. For example, at the table speed of 30 mm/rotation, images of 5-10 mm slices can be generated. Thicker slice (such as 10 mm) images can be generated prospectively, which provides the benefit of a reduced number of images and reduced image reconstruction time. At a later time, thinner slice images can be generated retrospectively using the same data. Such thinner slice images may be necessary depending on the clinical application needs. Such thinner slice images can be generated without rescanning the patient.
摘要:
An iron base alloy having high wear resistance at elevated temperatures with good oxidation resistance contains 1-2.8 wt. % carbon, 3-16 wt. % chromium, 1-8 wt. % vanadium, 0.5-5 wt. % niobium, up to 14 wt. % molybdenum and up to 14 wt. % tungsten, the molybdenum and tungsten combined comprising 6-14 wt. % of the alloy.
摘要:
A unique austenitic iron base alloy for wear and corrosion resistant applications, characterized by its excellent sulfuric acid corrosion resistance and good sliding wear resistance, is useful for valve seat insert applications when corrosion resistance is required. The alloy comprises 0.7-2.4 wt % carbon, 1.5-4 wt % silicon, 3-9 wt % chromium, less than 6 wt % manganese, 5-20 wt % molybdenum and tungsten combined, with the tungsten comprising not more than ⅓ of the total, 0-4 wt % niobium and vanadium combined, 0-1.5 wt % titanium, 0.01-0.5 wt % aluminum, 12-25 wt % nickel, 0-3 wt % copper, and at least 45 wt % iron.
摘要:
A unique iron base alloy for wear resistant applications, characterized in one aspect by its hardening ability when exposed to a certain temperature range, is useful for valve seat insert applications. The alloy also possesses excellent wear resistance, hot hardness and oxidation resistance. The alloy comprises less than 0.1 wt % carbon; about 18 to about 32 wt % molybdenum, about 6 to about 15 wt % chromium, about 1.5 to about 3% silicon, about 8 to about 15 wt % cobalt and at least 40% iron, with less than 0.5 wt % nickel. In another aspect, for lower temperature applications, the cobalt is optional, the nickel content can be up to 14 wt %, but the molybdenum must be in the range of about 29% to about 36%. In one further aspect, for higher temperature applications, the cobalt is optional, but may be used up to 15 wt %, nickel must be used at a level of between about 3 and about 14 wt %, and the molybdenum will be in the range of about 26 to about 36 wt %.
摘要:
A wear resistant alloy is provided having a composition by weight of 1.0-2.5 C, 1.5-4.5 Si, 8.0-20.0 Cr, 9.0-20.0 W and/or Mo, 0.5-2.0 Nb, 20.0-40.0 Fe, and the balance being Ni (>25.0). This alloy provides excellent wear resistance and good hot hardness with relatively low cost compared to prior art nickel base alloys. The alloy has particular use as a valve seat insert materials in diesel fuel internal combustion engines.
摘要:
Methods and apparatus for a multislice graphic Rx display which, in one embodiment, determines a true image location in the Z axis, selects a the correct scan data for image generation, and if a scan is initiated via the GUI or via graphic Rx, determines the affect on the ISO center and DFOV, are described. More particularly, the system determines the offset from the scan plane for each image plane, so that the true image location in Z is displayed. The image offset from the scan plane is a function of the detector row thickness, the number of detector rows, the scan pitch (helical scanning only), the image thickness, and the gantry tilt angle. Further, the image thickness is selected by the user via the GUI, and constrains the image interval which is displayed on the graphic Rx display. Based on image thickness and image interval, the correct scan data is selected so that images are generated at locations exactly matching those shown on the graphic Rx display. Also, if a scan is prescribed either via the GUI or graphic Rx display, the affect on ISO center and DFOV is determined. This information is automatically updated on the graphic Rx display by modifying the cut-line position up/down to show ISO affect and by modifying the cut-line length to show DFOV.