79 results about "Effective atomic number" patented technology

A method of obtaining a computed tomography image of an object includes determining linear terms and non-linear beam hardening terms in a pair of line integral equations for dual-energy projection data from inserting average and difference from average attenuation terms, obtaining an initial solution of the line integral equation by setting the non-linear beam hardening terms to zero, and iteratively solving the line integral equations to obtain one line integral equations for each basis material. Attenuation by the first basis material corresponds to a photoelectric attenuation process, and attenuation by the second basis material corresponds to a Compton attenuation process. The line integral equations can be inverted by an inverse Radon procedure such as filtered backprojection to give images of each basis material. The images of each basis material can then be optionally combined to give monochromatic images, density and effective atomic number images, or photoelectric and Compton processes images.

The invention discloses an explosive substance testing system apparatus and testing method thereof. The apparatus includes an X-ray light path subsystem, a detecting subsystem, a servo subsystem and a computer subsystem, wherein the light path subsystem includes a 75Kev and a 150Kev energy segment white light sources; the light path subsystem and the detecting subsystem are totally mounted on a multiple shaft mechanical platform, at different angle positions at the same side relative to the object, so as to configure a Compton backscattering geometric light path. The testing method includes a computer software control method and a data processing method, including: adopting a control method integrating the scanning detecting and tracking detecting, acquiring the density information and Compton scattering energy difference pair information data of the object by a solid state detector to execute data-handling and characteristic matching, obtaining the density and effective atomic number information of the object, and determining whether the object is the explosive substance and the affiliated species by the pattern recognition, thereby implementing the quick, safe and nondestructive testing, which is suitable for flow ability test of case or human body carrying explosive substance.

A method and a device are proposed for determining the type of fluid in a fluid mass in an object. X-ray attenuation data is supplied from one or a plurality of X-ray recordings of an object area including the fluid mass in the object, which were acquired with at least two different X-ray spectra or detector weightings. The X-ray attenuation data is used to determine values for effective atomic number and density for the fluid mass and average these to obtain a mean value for effective atomic number and density for the fluid mass. Comparison data is also supplied, which indicates fluctuation ranges for combinations of effective atomic number and density for different types of fluid. The mean values for effective atomic number and density of the fluid mass are compared with the comparison data to determine the fluctuation range and thereby the type of fluid, into which the two mean values fall. The method and associated device can be used to determine the type of fluid in a fluid mass in an object in a reliable and unambiguous manner.

A system and method of density and effective atomic number imaging include a computer programmed to acquire projection data from the detector of an unknown material at the time of projection data acquisition. The computer is also programmed to generate a density image for the unknown material based on a calibration of two or more known basis materials and to generate an effective atomic number (Z) for the unknown material based on the calibration of two or more known basis materials and based on a function arctan of a ratio of atomic numbers of the two or more known basis materials. The density and effective atomic number images are stored to a computer readable storage medium.

A method for estimating effective atomic number and bulk density of objects, such as rock samples or well cores, using X-ray computed tomographic imaging techniques is provided. The method effectively compensates for errors in the interpretation of CT scan data and produces bulk densities which have lower residual error compared to actual bulk densities and produces bulk density—effective atomic number trends which are consistent with physical observations.

The invention discloses a safety check system applying an X-ray multi-effect detection fusion technology which comprises an X-ray source, a collimator, a chopped-wave device, a dual-energy transmission detector, a forward scattering detector, a backward scattering detector, a signal processor, a computer system, a monitor and a conveying system, wherein the forward and the backward scattering detectors are positioned at two sides of the X-ray beam at a flying spot; the dual-energy transmission detector is positioned opposite the X-ray source; the forward scattering detector is positioned at one side of the dual-energy transmission detector; the backward scattering detector is positioned at one side of the X-ray source; and the dual-energy transmission detector, the forward scattering detector and the backward scattering detector are all connected with the signal processor which is connected with the computer system. The special algorithm can accurately and automatically identify target materials according to two characteristic quantities of effective atomic number Zeff and density of compositions of an obtained object to be checked, and give a red mark on an image, thus improving the detectivity and reducing the rate of false alarm.

The invention discloses a device for measuring an effective atomic number of a substance, which comprises an X ray source which emits X rays with different energy to a measured object, a Cerenkov detector which receives the X rays passing through the measured object and generates a first electrical signal, an energy depositing detector which receives the X rays passing through the measured object and generates a second electrical signal, and a processor which is used for acquiring the effective atomic number of the measured object according to the first electrical signal and the second electrical signal. The invention also discloses a method for measuring the effective atomic number of the substance. The method for measuring the effective atomic number of the substance by combining the Cerenkov detector and the energy depositing detector ensures that X-ray photons with high energy are more easy to form large signals during the detection of the Cerenkov detector compared with the X-ray photons with low energy, so the resolution effect of the acquired effective atomic number of the substance is enhanced.

Based on counts detected by a photon counting detector, a characteristic of X-ray attenuation amounts μt is acquired for each X-ray energy bin. This characteristic is defined by a plurality of mutually different known thicknesses t and linear attenuation coefficients in the X-ray transmission direction. This substance is composed of a material which is included in an object and which is the same in type as the object or which can be regarded as being similar to the object in terms of the effective atomic number. Correcting data for replacing the characteristic of the X-ray attenuation amounts μt by a linear target characteristic are calculated. The linear target characteristic is set to pass through the origin of a two-dimensional coordinate having a lateral axis assigned to thicknesses t and a longitudinal axis assigned to the X-ray attenuation amounts μt. The correcting data are calculated for each X-ray energy bin.

A method of and a system for identifying objects using histogram segment 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 method comprises: computing a density histogram for each potential threat object; smoothing the density histogram using a low-pass filter; identifying peaks in the smoothed density histogram; assigning a segment to each peak; computing histogram segment features for each segment; classifying each potential threat object into a threat or a non-threat using computed features.

A method of and a system for spectral correction in multi-energy computed tomography are provided to correct reconstructed images, including high-energy CT images and Z (effective atomic number) images, for spectral variations, which include time variations on a scanner due to HVPS drift and scanner to scanner variations due to the beamline component differences. The method uses a copper filter mounted on the detector array for tracking the spectral changes. The method comprises: generating copper ratios; computing working air tables; calculating scales and offsets; and correcting high-energy CT images and Z images using calculated scales and offsets. The method further includes an off-line calibration procedure to generate necessary parameters for the online correction.

[Problems to be Solved] A phoswich radiation detector, which can easily discriminate between detection signals on gamma rays and thermal neutrons, and which can selectively acquire signals on thermal neutrons, is provided.

[Means to Solve the Problems] In a phoswich radiation detector having two scintillators and discriminating between thermal neutrons and gamma rays, the detector comprises a scintillator for detecting thermal neutrons, such as LiCaAlF₆:Eu, which has a light yield of more than 1500 photons/neutron, and a scintillator for detecting gamma rays, which has a permeable end on a shorter wavelength than the light emission wavelength of the thermal neutron scintillator. The scintillator for detecting gamma rays is characterized by being either an organic solid scintillator, such as a plastic scintillator, which does not contain a total amount of 10 mol % or more of elements selected from ⁶Li, ¹⁰B and Gd, or an inorganic single crystal scintillator, such as lithium glass (containing ⁶Li and Ce) or BGO, which has an effective atomic number Z_eff of 30 or larger and which does not contain a total amount of 10 mol % or more of elements selected from ⁶Li, ¹⁰B and Gd.

A method for determining a type of substance is described. The method includes determining an effective atomic number of the substance based on a measured ratio of numbers of detected x-ray scatter photons in a diffraction profile.

A system and methods for characterizing regions within, or on, an inspected object, wherein a lower-Z scattering material and a higher-Z material may both lie along a common line of sight. The inspected object is scanned with penetrating radiation characterized by an energy distribution, and penetrating radiation scattered by the inspected object is detected in a manner that generates two detector signals that distinguish between materials of higher and lower effective atomic number under distinct sets of conditions with respect to the energy distribution of the penetrating radiation. An image is generated, based on a function of the two detector signals, as is a differential image, so as to allow distinction of higher-Z and lower-Z materials.