摘要:
It is disclosed a system and a method for reconstructing an image by using a straight-line trajectory scan to avoid image spatial resolution reduction due to interpolations in angular direction and detector direction during data rebinning. This system comprises: a projection data conversion section for converting projection data from straight-line trajectory scan into projection data under quasi-parallel-beam scan; a filtration section for obtaining filtered projection data by convoluting the projection data under quasi-parallel-beam scan with a predetermined convolutional kernel; and a back-projection section for reconstructing an image by back-projecting the filtered projection data with a weighting factor. By using the inventive system and method, the spatial resolution in the reconstructed image is improved, and the influence of data truncation on the reconstructed image is reduced. The present invention applies the filtration and back-projection mode, and thus has general advantages of the filtration and back projection, such as simplicity and efficiency. And it is easy to be parallelized and accelerated.
摘要:
It is disclosed an imaging system comprising: radiation generating means including at least one radiation source for generating radiations; data acquiring means including an detector matrix faced the radiation source for obtaining projection data by receiving radiations penetrated through an object to be inspected; transporting means for making the object to be inspected between the radiation source and the detector matrix linearly moving relative to the radiation source and the detector matrix; and controlling and image processing means for controlling the radiation generating means, the data acquiring means and the transporting means, and for reconstructing an image of the object to be inspected from the projection data. The imaging system according to the present invention achieves a real stereoscopic radiography by using straight-line trajectory scan and reconstructing a tomographic or stereoscopic image through a straight-line filtered back-projection algorithm. The present imaging system has advantages of fast examination speed, no rotation, and out of large cone-angle problem in a circular-orbit cone-beam CT.
摘要:
It is disclosed a system and a method for reconstructing an image by using a straight-line trajectory scan to avoid image spatial resolution reduction due to interpolations in angular direction and detector direction during data rebinning. This system comprises: a projection data conversion section for converting projection data from straight-line trajectory scan into projection data under quasi-parallel-beam scan; a filtration section for obtaining filtered projection data by convoluting the projection data under quasi-parallel-beam scan with a predetermined convolutional kernel; and a back-projection section for reconstructing an image by back-projecting the filtered projection data with a weighting factor. By using the inventive system and method, the spatial resolution in the reconstructed image is improved, and the influence of data truncation on the reconstructed image is reduced. The present invention applies the filtration and back-projection mode, and thus has general advantages of the filtration and back projection, such as simplicity and efficiency. And it is easy to be parallelized and accelerated.
摘要:
It is disclosed an imaging system comprising: radiation generating means including at least one radiation source for generating radiations; data acquiring means including an detector matrix faced the radiation source for obtaining projection data by receiving radiations penetrated through an object to be inspected; transporting means for making the object to be inspected between the radiation source and the detector matrix linearly moving relative to the radiation source and the detector matrix; and controlling and image processing means for controlling the radiation generating means, the data acquiring means and the transporting means, and for reconstructing an image of the object to be inspected from the projection data. The imaging system according to the present invention achieves a real stereoscopic radiography by using straight-line trajectory scan and reconstructing a tomographic or stereoscopic image through a straight-line filtered back-projection algorithm. The present imaging system has advantages of fast examination speed, no rotation, and out of large cone-angle problem in a circular-orbit cone-beam CT.
摘要:
In a linear track scanning imaging system and method, the imaging system may include: a ray generating unit having a plurality of ray sources that emit beams alternately, only one ray source at a time; an actuating arrangement causing an object under examination to move with respect to the linear track scanning imaging system along a linear track, leading the object to pass through a scanning area of the linear track scanning imaging system; a data collecting unit that collects projection data of the object for each ray source; an imaging unit that reconstructs an image of the object under examination based on the projection data collected for each ray source; and a display unit for displaying the reconstructed image.
摘要:
A cargo security inspection system inspecting an object moving through the system, including: a mechanical conveyance unit carrying, conveying, and defining a travel path of the object in the system; a radiation-generating unit generating ray beams for transmitting through the object; and a data collecting unit collecting transmission data about the rays having already transmitted through the object and processing the transmission data; wherein the travel path includes at least two linear sub-paths at an angle relative to each other; the data collecting unit includes at least two detector arrays receiving ray beams, each detector array corresponding to one linear sub-path, a receiving plane of each of the detector arrays disposed parallel to its corresponding linear sub-path; and in use, the radiation-generating and data collecting units remain stationary, and the object travels along its travel path and only translates on the at least two linear sub-paths without any rotation.
摘要:
A cargo security inspection system inspecting an object moving through the system, including: a mechanical conveyance unit carrying, conveying, and defining a travel path of the object in the system; a radiation-generating unit generating ray beams for transmitting through the object; and a data collecting unit collecting transmission data about the rays having already transmitted through the object and processing the transmission data; wherein the travel path includes at least two linear sub-paths at an angle relative to each other; the data collecting unit includes at least two detector arrays receiving ray beams, each detector array corresponding to one linear sub-path, a receiving plane of each of the detector arrays disposed parallel to its corresponding linear sub-path; and in use, the radiation-generating and data collecting units remain stationary, and the object travels along its travel path and only translates on the at least two linear sub-paths without any rotation.
摘要:
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.
摘要:
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.
摘要:
A method of image information enhancement in radiography relates to image information processing techniques in radiography. The method comprising steps of: normalizing an acquired image A(x,y) to form a normalized image B(x,y); filtering the normalized image B(x,y) by a low-pass filter to obtain an filtered image C(x,y); calculating a relative standard deviation for each pixel in the image A(x,y), three times the relative standard deviation being an edge threshold for each pixel; thresholding a difference image obtained by subtracting the filtered image C(x,y) from the normalized image B(x,y) by using the edge threshold for each pixel to form a threshold-processed image D(x,y); enhancing a contrast of the threshold-processed image D(x,y) by using a non-linear function to form a contrast-enhanced image E(x,y); determining a enhancement coefficient a(x,y); obtaining a edge-enhanced image F(x,y) by multiplying the enhancement coefficient a(x,y), the contrast-enhanced image E(x,y) and the filtered image C(x,y); and generating a resulting image by multiplying a sum of the edge-enhanced image F(x,y) and the filtered image C(x,y) with the maximum value Amax As compared with the prior arts, the inventive method has a fast processing speed for image information enhancement and a simple algorithm, images clearly, eliminates noises in the images, and satisfies the requirements of relatively more enhancement to the contrast of the dark regions in the scanned images.