97 results about "Dual energy ct" patented technology

Disclosed are a method and a device for security-inspection of liquid articles with dual-energy CT imaging. The method comprises the steps of obtaining one or more CT images including physical attributes of liquid article to be inspected by CT scanning and a dual-energy reconstruction method; acquiring the physical attributes of each liquid article from the CT image; and determining whether there are drugs concealed in the inspected liquid article based on the difference between the acquired physical attributes and reference physical attributes of the inspected liquid article. The CT scanning can be implemented by a normal CT scanning technique, or a spiral CT scanning technique. In the normal CT scanning technique, the scan position can be preset, or set by the operator with a DR image, or set by automatic analysis of the DR image.

A CT system includes a rotatable gantry having an opening for receiving an object to be scanned and an x-ray source coupled to the gantry and configured to project x-rays through the opening. The x-ray source includes a target, a first cathode configured to emit a first beam of electrons toward the target, a first gridding electrode coupled to the first cathode, a second cathode configured to emit a second beam of electrons toward the target, and a second gridding electrode coupled to the second cathode. The system includes a generator configured to energize the first cathode to a first kVp and to energize the second cathode to a second kVp, and a detector attached to the gantry and positioned to receive x-rays that pass through the opening. The system also includes a controller configured to apply a gridding voltage to the first gridding electrode to block emission of the first beam of electrons toward the target, apply the gridding voltage to the second gridding electrode to block emission of the second beam of electrons toward the target, and acquire dual energy imaging data from the detector.

To prevent patients from being overexposed or underexposed, it has been attempted to modulate either voltage or current in conventional single energy CT systems. The voltage modulation causes incompatibility in projection data among the views while the current modulation reduces only noise. To solve these and other problems, dual energy CT is combined with voltage modulation techniques to improve the dosage efficiency. Furthermore, dual energy CT has been combined with both voltage modulation and current modulation to optimize the dosage efficiency in order to minimize radiation to a patient without sacrificing the reconstructed image quality.

An imaging system includes an x-ray source that emits a beam of x-rays toward an object to be imaged, a detector that receives the x-rays attenuated by the object, a spectral notch filter positioned between the x-ray source and the object, a data acquisition system (DAS) operably connected to the detector, and a computer operably connected to the DAS and programmed to acquire a first image dataset at a first kVp, acquire a second image dataset at a second kVp that is greater than the first kVp, and generate an image of the object using the first image dataset and the second image dataset.

A method for calibrating a dual-energy CT system and an image reconstruction method are disclosed to calculate images of atomic number and density of a scanned object as well as its attenuation coefficient images at any energy level. The present invention removes the effect from a cupping artifact due to X-ray beam hardening. The method for calibrating a dual-energy CT system is provided comprising steps of selecting at least two different materials, detecting penetrative rays from dual-energy rays penetrating said at least two different materials under different combinations of thickness to acquire projection values, and creating a lookup table in a form of correspondence between said different combinations of thickness and said projection values. The image reconstruction method is provided comprising steps of scanning an object with dual-energy rays to acquire dual-energy projection values, calculating projection values of base material coefficients corresponding to said dual-energy projection values based on a pre-created lookup table, and reconstructing an image of base material coefficient distribution based on said projection values of base material coefficients. In this way, images of atomic number and density of an object as well as its attenuation coefficient images can be calculated from the images of the distribution of base material coefficients. Compared with the prior art technique, the method proposed in the present invention has advantages of simple calibration procedure, high calculation precision and invulnerability to X-ray beam hardening.

A system and method for dual energy CT spectral imaging that provides for accurate blood vessel stenosis visualization and quantification is disclosed. The CT system includes an x-ray source configured to project x-rays toward a region-of-interest of a patient that includes a blood vessel in a stenosed condition and having a plaque material therein. The CT system also includes an x-ray detector to receive x-rays emitted by the x-ray source and attenuated by the region-of-interest, a data acquisition system (DAS) operably connected to the x-ray detector, and a computer programmed to obtain a first set of CT image data for the region-of-interest at a first chromatic energy level, obtain a second set of CT image data for the region-of-interest at a second chromatic energy level that is higher than the first chromatic energy level, and identify plaque material in the region-of-interest by analyzing the second set of CT image data.

In dual energy CT, through basis material decomposition (BMD), a pair of density images can be reconstructed. The noises in this image pair are negatively correlated due to the BMD process. A technique is presented for obtaining the monochromatic images at desired energy levels with reduced correlation noise. The technique includes obtaining a plurality of optimum attenuation coefficients for an energy level, selecting a desired energy level, obtaining a plurality of desired attenuation coefficients for the desired energy level, computing a scaling factor for a corresponding noise component based on the optimum attenuation coefficients and the desired attenuation coefficients, and generating a monochromatic image based upon the scaling factor.

Three or more materials are advantageously separated from dual energy data by using a material separation technique. To effectively separate material clusters, a density plot is introduced to automatically render cluster separations. Initially, the projection data optionally undergo data-domain dual energy decomposition. Then, the image data is plotted in a vector plot whose axes are the low HU values and the high HU values. For a given data point in the vector plot, a number of data points is counted within in a region of interest surrounding the given data point to generate a density plot where each point now represents a density level surrounding the data point. Thus, clustering of a certain material is visualized by a predetermined color assignment scheme. Furthermore, special image processing methods such as Gaussian decomposition are used to improve the accuracy of material separation. In addition, the HSL color model may be used for better visualization and to bring a new dimension in material separation display.

A CT system includes a rotatable gantry having an opening for receiving an object to be scanned, and a controller configured to obtain kVp projection data at a first kVp, obtain kVp projection data at a second kVp, extract data from the kVp projection data obtained at the second kVp, add the extracted data to the kVp projection data obtained at the first kVp to generate mitigated projection data at the first kVp, and generate an image using the mitigated projection data at the first kVp and using the projection data obtained at the second kVp.