摘要:
A method and apparatus compress projection data and store the compressed projection data in a rotatable part that is mounted for rotation within a stationary part. The data acquisition source, compressor and storage device are connected to the rotatable part. The compressor compresses projection data samples provided by the data acquisition source to form compressed packets. The compressed packets are stored in the storage device, for example one or more solid state drives mounted on the rotatable part. A data access array contains information related to the location of the stored compressed packets. Compressed packets are retrieved and transferred across the interface to the stationary part. A decompressor at the stationary part decompresses the received compressed packets to form decompressed samples of the corresponding projection data. This abstract does not limit the scope of the invention as described in the claims.
摘要:
A method and apparatus compress projection data and store the compressed projection data in a rotatable part that is mounted for rotation within a stationary part. The data acquisition source, compressor and storage device are connected to the rotatable part. The compressor compresses projection data samples provided by the data acquisition source to form compressed packets. The compressed packets are stored in the storage device, for example one or more solid state drives mounted on the rotatable part. A data access array contains information related to the location of the stored compressed packets. Compressed packets are retrieved and transferred across the interface to the stationary part. A decompressor at the stationary part decompresses the received compressed packets to form decompressed samples of the corresponding projection data. This abstract does not limit the scope of the invention as described in the claims.
摘要:
A computed tomography system has a stationary part, a rotatable part mounted for rotation around an object to be examined and an interface between the stationary part and the rotatable part. The rotatable part includes an x-ray source, a sensor array for detecting x-rays passing through the object to produce projection data samples, a compressor that compresses the projection data samples and a storage device that stores the compressed samples. The storage device on the rotatable part can include one or more solid state drives. For image reconstruction, the compressed samples are retrieved from the storage device, transferred across the interface to the stationary part. A decompressor at the stationary part decompresses the received compressed samples and provides decompressed samples to the image reconstruction processor. This abstract does not limit the scope of the invention as described in the claims.
摘要:
A computed tomography system has a stationary part, a rotatable part mounted for rotation around an object to be examined and an interface between the stationary part and the rotatable part. The rotatable part includes an x-ray source, a sensor array for detecting x-rays passing through the object to produce projection data samples, a compressor that compresses the projection data samples and a storage device that stores the compressed samples. The storage device on the rotatable part can include one or more solid state drives. For image reconstruction, the compressed samples are retrieved from the storage device, transferred across the interface to the stationary part. A decompressor at the stationary part decompresses the received compressed samples and provides decompressed samples to the image reconstruction processor. This abstract does not limit the scope of the invention as described in the claims.
摘要:
A method of and a system for identifying objects using local distribution features from multi-energy CT images are provided. The multi-energy CT images include a CT image, which approximates density measurements of scanned objects, and a Z image, which approximates effective atomic number measurements of scanned objects. The local distribution features are first and second order statistics of the local distributions of the density and atomic number measurements of different portions of a segmented object. The local distributions are the magnitude images of the first order derivative of the CT image and the Z image. Each segmented object is also divided into different portions to provide geometrical information for discrimination. The method comprises preprocessing the CT and Z images, segmenting images into objects, computing local distributions of the CT and Z images, computing local distribution histograms, computing local distribution features from the said local distribution histograms, classifying objects based on the local distribution features.
摘要:
A method of and a system for destreaking the photoelectric image in multi-energy computed tomography are provided, wherein the photoelectric projections are generated from the projection data acquired using at least two x-ray spectra for scanned objects; wherein a neighboring scheme is provided; the method comprises computing the statistics including mean and standard deviation using the neighboring scheme; calculating an upper limit and a lower limit from the computed statistics; detecting outliers in the photoelectric projections using the upper and lower limits; and replacing values of outliers using the upper or lower limit.
摘要:
A method of and a system for automatic object display of volumetric CT data for fast on-screen threat resolution are disclosed, wherein the CT data includes a CT image in a single energy CT scanner, or a CT image and a Z image in a multi-energy CT scanner, and a label image defining each object as a plurality of voxels of the volumetric CT data. The method comprises generating volumetric CT image data corresponding to a scanned bag; performing automatic threat detection to generate a label image; processing the volumetric CT data and the label image to obtain visualization parameters for each object; automatically generating display images for each object using corresponding visualization parameters; and displaying the generated display images for on-screen threat resolution.
摘要:
A method of decomposition of projection data is provided, wherein such projection data includes input projection data acquired using at least two x-ray spectra for a scanned object, including low energy projection data (PL) and high energy projection data (PH); the method comprises solving the projections PL and PH to determine a photoelectric line integral (Ap) component of attenuation and a Compton line integral (Ac) component of attenuation of the scanned object using a multi-step fitting procedure and constructing a Compton image Ic and a photoelectric image Ip from the Compton line integral and photoelectric line integral.
摘要翻译:提供了投影数据的分解方法,其中这种投影数据包括使用扫描对象的至少两个X射线光谱获取的输入投影数据,包括低能量投影数据(P L L L L)和高 能量投影数据(P< H>); 该方法包括求解投影P L L和P H H以确定衰减的光电线路积分(A> P)分量和康普顿线积分 使用多步骤拟合程序对扫描对象的衰减的分量进行分析,并且构建康普顿图像I C和光电图像I< P< SUB>从康普顿线积分和光电线路积分。
摘要:
A method of and a system for stabilizing High Voltage Power Supply (HVPS) DC and AC voltages in multi-energy X-ray computed tomography scanners are provided. The method comprises generating filter ratios, computing DC and AC voltages, and feeding back the computed DC and AC voltages to the commanded voltages. The filtered ratios including an air ratio and a copper ratio are modeled as nonlinear functions of the DC and AC voltages. Computing DC and AC voltages include computing an m-ratio and an n-ratio. The parameters of the nonlinear model comprise an exponent parameter and a set of polynomial coefficients. The parameters are determined by a calibration procedure, which performs scanning at different combination of DC and AC voltages. The optimal parameters are obtained through a nonlinear least square minimization, which is solved through a brute force search over the exponent parameter and a closed form solution of the polynomial coefficients. Feeding back the computed DC and AC voltages include comparing the computed voltages with commanded voltages, integrating the difference between the computed voltages and commanded voltages, and adding the integrated voltage differences to the commanded voltages.
摘要:
A method and apparatus for performing CT scans of baggage being carried or loaded onto commercial aircraft are described. The CT baggage scanner of the invention includes numerous features which provide the system with high baggage throughput on the order of seven hundred bags per hour as well as improved image quality and accurate target detection. In one aspect, the scanner includes an adaptive image reconstruction window which identifies data collected from the field of view that are not related to the baggage being scanned. These unrelated data are excluded from the image reconstruction process, resulting in greatly reduced reconstruction time and increased baggage throughput. The invention also includes the capability of performing calibration “air scans” with objects such as the system conveyor in the field of view. Data gathered during the calibration scan are applied to a threshold, and data exceeding the threshold are assumed to be from X-rays that are unobstructed by objects in the field of view and are therefore used to perform the air calibration. The baggage scanner can also analyze scan data to identify shapes of objects, particularly, objects formed in the shape of a sheet. This greatly improves the ability of the system to detect sheet explosives. The system also compensates for detector dark currents and provides dark current offsets which can be dependent upon detector temperature.