161 results about "Conical beam" patented technology

A radiation therapy system that includes a radiation source that moves about a path and directs a beam of radiation towards an object and a cone-beam computer tomography system. The cone-beam computer tomography system includes an x-ray source that emits an x-ray beam in a cone-beam form towards an object to be imaged and an amorphous silicon flat-panel imager receiving x-rays after they pass through the object, the imager providing an image of the object. A computer is connected to the radiation source and the cone beam computerized tomography system, wherein the computer receives the image of the object and based on the image sends a signal to the radiation source that controls the path of the radiation source.

Described herein are improved methods for correcting cone beam computed tomography signals to reduce scatter contamination contained therein. Generally, the improved methods involve generating a plurality of two-dimensional projection images of a subject from a three-dimensional multi-detector computed tomography image of the subject. This is followed by subtracting the plurality of two-dimensional projection images from a plurality of two-dimensional cone beam projection images of the subject to produce a plurality of two-dimensional estimated error projections that comprise an estimated error in the plurality of two-dimensional cone beam projection images. The plurality of two-dimensional estimated error projection images are subtracted from the plurality of two-dimensional cone beam projection images to generate a plurality of two-dimensional corrected cone beam projection images. A three-dimensional corrected cone beam computed tomography image of the subject is then constructed from the plurality of two-dimensional corrected cone beam projection images.

A medical accelerator system consisting of coplanar and non-coplanar beams, on line magnetic resonance anatomic and functional imaging and cone beam computed tomographic imaging for single session image guided all field simultaneous radiation therapy and radiosurgery is provided. This system enables single session simulation, field-shaping block making, treatment planning, dose calculations and treatment of tumors. The radiation exposure time to the tumor and the normal tissue is reduced to a few seconds to less than a minute. In filed intensity modulated radiation is rendered by combined divergent and pencil beam, multiple smaller fields within a larger field, selectively varying beam's energy, dose rate and beam weight. Since all the treatment fields are treated simultaneously the dose rate at the tumor site is the sum of each of the converging beam's dose rate at depth. This super-high biological dose rate impairs the lethal and sublethal damage repair.

Systems and methods are provided for reconstructing projection data that is mathematically complete or sufficient acquired using a computed tomography (CT) system. In one embodiment, a set of projection data representative of a sampled portion of a cylindrical surface is provided. The set of projection data is reconstructed using a suitable cone-beam reconstruction algorithm. In another embodiment, two or more sets of spatially interleaved helical projection data are processed using helical interpolation. The helically interpolated set of projection data is reconstructed using a two-dimensional axial reconstruction algorithm or a three-dimensional reconstruction algorithm.

A CT imaging system includes a two-dimensional detector array and an x-ray source that both revolve around the subject during a scan. The x-ray source produces a cone beam of x-rays and the focal point of this cone beam is electrically moved to different locations along the z-axis to increase the z-axis extent of the ROI that can be imaged without patient table movement. Different focal point scan patterns are described for a variety of different clinical applications.

A system includes acquisition of a three-dimensional cone beam image, and determination of a dose to be delivered based on the three-dimensional image and on parameters of a treatment beam to deliver the dose. Some systems may include modification of a three-dimensional cone beam image to correct for scatter radiation, and determination of a dose based on the modified three-dimensional cone beam image.

A dual-energy x-ray source located a distance of one half of the maximum width of the subject from the subject emits a cone beam to a horizontal slit in an x-ray-blocking sheet, producing a fan beam that is chopped into a pencil beam by a rotating disk with radial slots. The pencil beam sweeps a subject, producing backscatter read by a plastic scintillator detector situated very close to and curved around the sides of the subject. The entire assembly translates vertically to produce a complete image of the subject. Pencil beam area is increased farther from the center by increasing the width of the slit toward both ends and increasing the width of the slots toward the outer end. High and low peak x-ray energies of 50 KeV or more and 30 KeV or less, respectively, enable differentiation between innocent and contraband materials that both contain low Z materials.

Disclosed are methods for reconstructing a three-dimensional image of an object's volume of interest using computed tomography that employs conical-beam, intensity-modulated projections of this object. In one embodiment, a plurality of collimating devices serves to modulate the aperture of the radiation source thereby acting to modulate the intensity of the source upon the object. Also provided are image processing devices, examination apparatus, as well as a computer-readable medium and a program element adapted and configured to perform aspects of the methods disclosed herein.

An X-ray CT system is equipped with a gantry, couch and control cabinet and configured to scan a cone-beam X-ray toward an object along a given orbit to acquire cone-beam data in which a three-dimensional distribution of an X-ray absorption coefficient within the object is reflected. The control cabinet decides a degree of reliability for the cone-beam data according to an acquisition time of the cone-beam data, and then decides a weight for three-dimensional Radon data from the cone-beam data on the basis of the degree of reliability. Using this weight, the control cabinet reconstructs the three-dimensional Radon data based on a three-dimensional reconstruction algorithm. Thus, when the three-dimensional reconstruction algorithm for cone-beam CT is applied to medical CT, artifacts attributable to object's motion can be suppressed and temporal resolution can be improved.

Raw cone beam tomography projection image data are taken from an object and are denoised by a wavelet domain denoising technique and at least one other denoising technique such as a digital reconstruction filter. The denoised projection image data are then reconstructed into the final tomography image using a cone beam reconstruction algorithm, such as Feldkamp's algorithm.

The invention provides a microphone array device and a beam forming method thereof. The microphone array device can effectively eliminate noise and realize the directive property of a conical beam. Compared with prior art, the invention restrains the noise by controlling the updating of the coefficient of a self-adapting filter with the coefficient a, and the efficiency is pretty high.

A 3D metal artifacts correction technique corrects the streaking artifacts generated by titanium implants or other similar objects. A cone-beam computed tomography system is utilized to provide 3D images. A priori information (such as the shape information and the CT value) of high density sub-objects is acquired and used for later artifacts correction. An optimization process with iterations is applied to minimize the error and result in accurate reconstruction images of the object.

The invention discloses a method for online detecting an electronic element by a translational type micro focus CT (Computerized Tomography) detection device, and the method is realized as follows: when the detection is started, the electronic element is scanned by a conical ray beam generated by a ray generation device; and ray projection data is acquired by a ray detection and data acquisition device, and then is transmitted to a control and image processing system for imaging including digital radiation (DR) imaging and computerized tomography (CT) imaging. When the CT imaging is performed, the CT image can be reconstructed according to incomplete projection data acquired through ray scanning by the translational type conical beam and adopting translational type conical beam CT iterative reconstruction algorithm based on subdomain equalization and total variation minimization, so as to obtain a high quality three-dimensioanl CT image. The method is used for online detecting the electronic element on the production line with high precision, can perform amplification DR image and three-dimensional CT image for internal and external structures of the electronic element; the device has simple structure and high scanning efficiency; and further, material deficiency and assembly deficiency of the electronic element can be detected efficiently.

This invention uses the CT (Computer Tomography) principle to obtain nondestructive image of different x-ray attenuation inside an object. In order to have fast data acquisition and high resolution, a cone beam source and a 2-D detector surface are necessary. However, for good cone beam image reconstruction datasets from 2 orthogonal planes about the object are required (U.S. Pat. No. 5,375,156,) December 1994 of Kuo-Petravic and Hupke), thus making its implementation difficult as well as raising the cost of the scanner. Here, we suggest a practical way of implementing the 2 orthogonal planes theory by replacing the 2 gantry rotations by 2 rotations of only one fixed gantry and one movement of the object position, making it simple and low cost. This method is applied to the nonintrusive inspection of baggage or imaging of mice for pharmaceutical purposes where the object has to remain in a horizontal plane throughout the procedure. This algorithm can also be applied to nondestructive testing of any solid materials, for example: imperfections in semi-conductors, fracture in turbo-engine blades, composition of uranium drums etc.

The invention discloses a method for realizing laser focusing, which utilizes reflection of a reflector and focusing of a focus lens to exchange an inner position and an outer position of a light spot of a laser beam in rings along the radial direction and to focalize. The method is characterized by comprising the following steps: the laser beam is reflected to a turbinate annular beam; the turbinate annular beam is converted into an annular beam; the annular beam is focused, so as to form an annular conical beam, and a hollow conical dark area is formed in the middle of the annular conical beam, thus obtaining a focusing spot of hollow annular light. The method solves the defects of laser focusing in the prior art and obtains a focusing spot with strong light encompassing weak light, almost uniform energy distribution and small gradient, thus improving the processing effect.

A scanning electron beam computed tomographic system eliminates axial offset between target and detector by disposing the target, collimator, and detector such that active portions of the target and detector are always diametrically opposite each other. This result is achieved by providing a helical target, collimator, and detector, or by providing planar target, collimator, and detector components that are inclined relative to the vertical axis such that active portions of the target and detector are always diametrically opposite each other. Either configuration eliminates cone beam error and the necessity to correct for same. Further, the system can provide multi-slice scanning of an object that is in constant motion at a critical velocity, without having to interpolate data. Conventional helical scanning may still be undertaken. Detector elements can be disposed axially to improve signal/noise ratio and to produce a cone beam cancellation effect.

A method using a tow body and sensor array for locating an underwater location beacon is provided. The steps of the method are moving the body and array in a direction of motion; orientating the array orthogonal to the direction of motion; beamforming acoustic conical beams from the array onto a seafloor; detecting a time series of acoustic data channels from the beacon; converting the data channels into spatial beams of acoustic frequency; determining if a signal of the underwater location beacon is present from each spatial beam; calculating likelihood functions for locations of the beacon to represent an area of the seafloor from which the signal of the underwater location beacon is to have originated; accumulating likelihood functions for the location of the underwater location beacon over the course of a search pattern; and producing a grid for a beacon location based on the likelihood functions.