摘要:
A device for inspecting contraband in an aviation cargo container includes: a turntable and a scanning system, the scanning system including a radiation source; a detector; a radiation source mounting structure; and a detector mounting structure for mounting the detector. Each of said radiation source mounting structure and said detector mounting structure includes at least one column assembly. The radiation source and the detector are mounted on the column assembly and allowed to synchronously ascend and descend along said column assembly. By combining different movement modes of the turntable and the scanning system, the device of the present invention can scan the object in various scanning modes. The device is stable in structure, convenient in installation, and occupies a small space. The device can inspect aviation containers over two meters long and/or over two meters wide and achieve a relatively high passing rate of the objects.
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:
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:
Disclosed are a method and an apparatus for measuring terahertz time-domain spectrum, which relate to the field of terahertz time-domain spectrum. The method comprises the steps of: generating a first pulse laser beam from a first femtosecond laser device at a preset repetition frequency to generate THz pulses; generating a second pulse laser beam from a second femtosecond laser device at the repetition frequency; measuring electric field intensities of the THz pulses at respective phase differences between the first pulse laser beam and the second pulse laser beam; and obtaining a THz time-domain spectroscopy by performing Fourier transformation of data representative of the electric field intensities. Compared with prior art, THz spectrum measured according to the method and apparatus of present invention has higher spectroscopy resolution and broader detection range, which makes the technology of present invention have stronger capability for discriminating substances.
摘要:
The present invention relates to a radiation inspection system discloses a shielding door device for a radiation inspection system, comprising a door body, two guides located on two opposite sides of the door body, a rack, a gear and a motor. The two guides are fixed on an upper surface of a frame and the door body is movably connected to the two guides via bearings. The rack is fixed on a bottom of the door body and meshed with the gear. The gear is coupled with a shaft of the motor fixed on a lower surface of the frame. With the above configuration, the present invention is advantageous in automatic and complete shielding of the radiation inspection system without interference. In addition the shielding door can be controlled intelligently, so that accidental radiation leakage can be prevented.
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.
摘要:
A CT method and an apparatus for liquid safety-detection with a radiation source relate to a radiation imaging detecting technology field. The invention comprises using a radiation source, a detector and data collector, a computer data processor; and the main steps are: 1) a liquid article to be detected being placed onto a rotary platform which is rotatable; 2) the ray emitted from the radiation source passing through the liquid article, and being received and formed into projection data by the detector and data collector; and 3) the projection data being transmitted to the computer data processor, which processes it to obtain the liquid density of the detected article, compares the result with the densities of dangerous articles in a current database, and then visually displays the detected information of the detected liquid article. Comparing to the prior art, the invention has a small volume, a strong anti-interference, a high accuracy of detection, an easy shielding, and a high use safety and reliability.
摘要:
A boron-coated neutron detector, comprising a cathode tube with a plurality of passages formed therein along its longitudinal direction, the inner wall of each passage being coated with boron material; an electrode wire serving as an anode and arranged longitudinally in each of the passages, the electrode wire adapted to be applied with high voltage; and an insulating end plate to which each end of the cathode tube is fixed, the electrode wire being fixed to the cathode tube via the insulating end plate. Preferably, the cathode tube is formed by jointing a plurality of boron-coated substrates. The boron-coated neutron detector increases the detection efficiency of the neutron detector, which may reach or even exceed the detection efficiency of the 3He neutron detector of the same size, and the cost thereof is much cheaper than the 3He neutron detector.
摘要:
An X-ray imaging system comprising: an X-ray source, a source grating, a fixed grating module and an X-ray detector, which are successively positioned in the propagation direction of X-ray; an object to be detected is positioned between the source grating and the fixed gating module; said source grating can perform stepping movement in a direction perpendicular to the optical path and grating stripes; wherein the system further comprises a computer workstation for controlling said X-ray source, source grating and X-ray detector so as to perform the following processes: the source grating performs stepping movement in at least one period thereof; at each stepping step, the X-ray source emits X-ray to the object to be detected, and the detector receives the X-ray at the same time; wherein after at least one period of stepping and data acquisition, the light intensity of X-ray at each pixel point on the detector is represented as a light intensity curve; the light intensity curve at each pixel point on the detector is compared with a light intensity curve in the absence of the object to be detected, a pixel value of each pixel point is calculated from change in said light intensity curve; an image of the detected object is reconstructed according to the calculated pixel value.
摘要:
A photoneutron conversion target for generating photoneutrons by directing an x-ray beam at the photoneutron conversion target includes an elongated body having a first end and a second end. When the photoneutron conversion target is in use, the x-ray beam enters the body and propagates in a direction from the first end to the second end. The body of the photoneutron conversion target is shaped such that propagation of the x-ray beam is substantially proportionate to an intensity distribution of the x-ray beam, so that the greater an intensity of x-rays of the x-ray beam, the greater the propagation distance of the x-rays within the body of the photoneutron conversion target. The photoneutron conversion target according to the invention can make full use of the x-ray beam so as to increase a yield of photoneutrons.