97 results about "Dual energy ct" patented technology

A system and method for creating a combined or mixed-energy image using both low- and high-energy CT data sets acquired using a dual-energy CT system. The low- and high-energy datasets are mixed using desired weighting factors to mimic a “single-energy” image. The low-energy dataset provides data with improved contrast enhancement, but with increased noise level. The high-energy dataset provides data with lower contrast enhancement, but with better noise properties. By combining the low- and high-energy datasets in accordance with the present method, the resulting mixed-energy images utilize the information of full dose of radiation used in the dual-energy scan. A plurality of weighting metrics can be selected, including patient size, dose partitioning, or image quality, to determine the desired weighting factors based on the weighting metrics. By selecting the proper weight factors, image noise can be reduced and / or the contrast to noise ratio can be increased in the mixed-energy image.

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.

A CT system includes a gantry, an x-ray source, a generator configured to energize the x-ray source to a first kVp and to a second kVp, a detector, and a controller. The controller is configured energize the x-ray source to the first kVp for a first time period, subsequently energize the x-ray source to the second kVp for a second time period, integrate data for a first integration period that includes a portion of a steady-state period of the x-ray source at the first kVp, integrate data for a second integration period that includes a portion of a steady-state period of the x-ray source at the second kVp, compare a signal-to-noise ratio (SNR) during the first integration period (SNRH) and the second integration period (SNRL), adjust an operating parameter of the CT system to optimize an SNRH with SNRL, and generate an image using the integrated data.

The present technique provides for the generation of density maps using one or more basis material decomposition tables or functions. The basis material decomposition tables or functions are generated by simulating the system response to various lengths of basis materials using component characteristics of the CT system as well as the attenuation coefficient for the desired basis material. Measured projection data may be processed using the basis material decomposition tables or functions to provide a set of density line-integral projections that may be reconstructed to form a density map or image.

Two x-ray CT images are acquired of arterial plaque using x-rays at two different energy levels. The reconstructed images are normalized by adjusting pixel brightness until pixels depicting a region containing calcium have substantially the same brightness. The normalized images are subtracted to produce an image that depicts iron in the arterial plaque.

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.

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.

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.

A CT system includes a rotatable gantry having an opening for receiving an object to be scanned, an x-ray source coupled to the gantry and configured to project x-rays through the opening, a generator configured to energize the x-ray source to a first kVp and to a second kVp to generate the x-rays, and a detector having pixels therein, the detector attached to the gantry and positioned to receive the x-rays. The system includes a computer programmed to acquire a first view dataset and a second view dataset with the x-ray source energized to the first kVp, interpolate the first and second view datasets to generate interpolated pixels in an interpolated view dataset at the first kVp, using at least two pixels from each of the first and second view datasets to generate each interpolated pixel in the interpolated view dataset, and generate an image of the object using the interpolated view dataset.

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.

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.

According to certain embodiments of the invention, computer hardware and software can perform single or dual-energy decomposition calculations and predict CT values for either single-energy or dual energy CT from basis material decomposition estimates derived using theoretical models. Using that information, the computer hardware and software can (among other things) present one dimensional information from a CT scanner, such as representative pixel value, in two dimensions, such as a line in two dimensional basis material space.

A method and system for dual-energy X-ray CT are disclosed. In the method, two effects which are predominant, such as the Compton effect and the pair effect, are maintained, and influences of other effects such as the photoelectric effect are eliminated, thus increasing the material decomposition precision. The method and the system are advantageous in that errors caused by direct selection of two effect equations for atomic number Z calculation in material decomposition processes in present dual-energy CT (regardless of keV low energy or MeV high energy) methods can be effectively eliminated, thus greatly improving material decomposition and recognition accuracy of dual-energy CT; and the method and the system are of great significance for applications in clinical medicine, safety inspection, industrial nondestructive testing, and other fields.

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.

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 the inspected liquid article is dangerous based on the physical attributes. 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.

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.

The invention relates to the technical fields of medical dual-energy image decomposition and image processing, in particular to a dual-energy CT image decomposition method and particularly provides adual-energy CT image decomposition method based on a CNN (convolutional neural network). The dual-energy CT image decomposition method based on the CNN comprises the following steps: designing a CNN model to serve as a mapping function D (mu H, L; theta) of a dual-energy decomposition model; training the CNN with the CNN model and a training data set, and effectively estimating the CNN parameter theta; efficiently decomposing substrate materials of dual-energy CT images with the trained CNN and the CNN parameter theta obtained in step 2. Through establishment of the dual-input dual-output CNNmodel and cross convolution, reasonable shunt of different substrate materials of high-energy CT images and low-energy CT images is realized, so that quality of decomposition of the substrate materials of the dual-energy CT images is improved effectively.

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.

The present invention discloses a GPU parallel acceleration dual spectrum CT reconstruction method based on a CUDA architecture. Combined with the characteristic of dual energy CT reconstruction, the method of carrying out dual-energy CT rapid analysis reconstruction and obtaining four reconstruction images at the same by using the parallel ability of a GPU based on the CUDA architecture is provided, and the images comprises a post-processing and reconstructed high and low energy line attenuation coefficient image and pre-processing and reconstructed equivalent atomic number and electronic density images. The method has the advantages that the speed is accelerated, the efficiency is promoted, compared with an existing single CT acceleration reconstruction method, according to the dual-energy CT reconstruction method, under the premise of registration, the repeated weight calculation of an original projection and a decomposed projection in a weighting step is avoided, the time of repeatedly calculating the back-projection addresses of the four reconstruction images in a back-projection step is saved, the data access time of a calculation middle process can be reduced. Multiple real parts and imaginary parts can be fully utilized to carry out dual energy synchronization filtering in a filtering step, and when a reconstructed image is increased, no more back-projection time consumption is increased.

Disclosed is an image reconstruction method in a high-energy dual-energy CT system. The method comprises steps of scanning an objection with high-energy dual-energy rays to obtain high-energy dual-energy projection values, calculating projection values of base material coefficients corresponding to the dual-energy projection values on the basis of a pre-created lookup table or by analytically solving a set of equations, and obtaining an image of base material coefficient distribution based on the projection values of base material coefficients. The method provides a solution for reconstruction with high-energy dual energy CT technology and thus a more effective approach for substance identification and contraband inspection, thereby bringing a significant improvement on accuracy and efficiency in security inspection.

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.

The invention relates to a reconstruction and numerical value calibration method for a medical dual-energy computed-tomography (CT) electron density image. Reconstruction and numerical value calibration are carried out on a medical dual-energy-CT (DECT) electron density image according to a basal principle of base-material-decomposition DECT imaging as well as a linear relationship between combination of X-ray linear attenuation coefficients at a high energy level and a low energy level and a theoretical electron density value. When the method provided by the invention is applied to the tumor radiation therapy field for clinical application, the precision of target region positioning and accuracy of exposure dose calculation of a radiation therapy planning system can be improved.

The invention relates to the field of X-ray energy spectrum detection and analysis through a semiconductor detector, and provides an X-ray energy spectrum detection and reconstruction analysis methodfor dual-energy CT imaging. The method can achieve the analysis of the projection information of different energy sections for image reconstruction, can achieve the multi-energy dynamic combination imaging while reducing the radiation dosage, and enlarging the dynamic range of CT system imaging. Therefore, the method comprises the steps: Step1, defining a dynamic dual-energy window for scanning imaging; Step2: carrying out the X-ray exposure and collecting and storing photo-induced charges; Step3: carrying out the grouped accumulation of the information of the photo-induced charges in a semiconductor; Step4: solving a projection result of different types of high-low energy spectrum combinations under the condition that the primary X-ray exposure is achieved, wherein the projection result is used for imaging. The method is mainly used for the X-ray energy spectrum detection occasions.