Multi energy spectrum static CT + AI to create intelligent security inspection to make security insp

2022-04-14



Multi energy spectrum static CT + AI to create intelligent security inspection to make security inspection more intelligent

 

However, the existing CT devices usually use slip ring rotation in the process of data acquisition, which not only has limited scanning speed and huge volume, but also requires high machining accuracy and high cost, which limits its wide application in practice. In recent years, carbon nanotube X-ray tube technology has entered the practical field. Different from the traditional light source, it does not need to use high temperature to generate rays, but according to the discharge principle of carbon nanotube tip to generate cathode rays, target to generate x-rays. The utility model has the advantages of quick opening and closing, and smaller volume. This kind of X-ray source can be arranged into a ring to irradiate the object at different angles, and then it can be made into a "static CT" without rotation, which greatly improves the imaging speed. At the same time, because the structure of the slip ring is omitted, the cost is saved, and it is of great significance for the safety inspection and other fields.

 

According to "home of security inspection", there is no report on the comprehensive application of static CT technology and multi energy spectrum analysis technology in radiation imaging system. The existing static CT systems are all single energy systems, which can only reconstruct the linear attenuation coefficient of the tested substance, which greatly limits its recognition ability. However, if multi-spectrum technology is adopted, the static CT system of multi-spectrum will face some practical difficulties. On the one hand, in order to realize the multi energy spectrum analysis, the existing CT device usually uses a single energy X-ray source plus a multi energy detector. The detector that detects different energy X-rays is placed in front and back. The ray enters the detector that detects the lower energy X-ray first, and enters the detector that detects the higher energy X-ray after the energy spectrum shaping. Figure 1 shows the energy spectrum analysis method of slip ring CT using a single energy X-ray source 110 plus dual energy detectors 120 and 130 placed before and after. The light source and detector can rotate with the slip ring, and the detector does not need to cover a large angle. The low energy detector 120 and high energy detector 130 that any ray passes through are one-to-one correspondence, which is easy to conduct accurate multi energy spectrum analysis. While the static CT cancels the use of distributed light source 210 for slip ring structure, and detectors 220 and 230 need to cover a large angle range or even arrange in the form of a ring, as shown in Figure 2. In this way, if the multi-energy detectors 220 and 230 placed before and after are used, the problem of ray squint will be caused, and the degree of ray squint will be different in different angles. Squint not only brings the difficulty of high and low energy data registration, but also intensifies the crosstalk between adjacent detectors, resulting in the degradation of the resolution of the reconstructed image.

 

Full set intelligence adds machine learning algorithm to the security system. After a large number of image data recognition, artificial intelligence recognition model is established. The first step is to let the machine learn to distinguish the types of objects. When the data is accumulated to a certain extent, the identification of contraband can be realized. At present, the intelligent security inspection machine has been able to identify drugs, explosives and other prohibited dangerous goods.

It solves the problems of imaging and machine recognition, and also uploads the data to the "cloud". Data sharing can facilitate us to collect more materials, so as to improve our machine learning model. At the same time, in some specific scenarios, users can also analyze the data to draw the required conclusions. For example, when the security system is used in the logistics center, the package can be initially classified (based on Artificial Intelligence) in the background after security check and elimination of contraband. In this process, it not only saves the labor cost in the screening stage, but also makes statistics on the types, materials, quality and other data of parcels, so that the logistics organization can adjust the operation plan according to the data.

On the other hand, another method is often used to realize multi energy spectrum analysis of CT, that is, multi energy X-ray plus single energy detector is used to obtain scanning under different energy by high-speed switching of X-ray between multiple energies during the rotation of slip ring. However, there are some shortcomings in this method. The slip ring rotates at a high speed when the X-ray source switches between multiple energies, resulting in the deviation of projection angle between the high and low energy data. When the frequency of the X-ray source energy switching is high, the deviation is generally small and can be ignored. If this method is applied to the static CT, it is necessary to set the adjacent X-ray source in the multi-point source as Due to different energy, the number of X-ray sources can not be very large due to cost, process and other factors, so the projection angle deviation between high and low energy data can not be ignored, which affects the accuracy of multi energy spectrum analysis.

 

The transmission mechanism carries the linear movement of the inspected object; the distributed ray source includes a plurality of ray source points arranged on a plane perpendicular to the movement direction of the inspected object, at least partially surrounds the inspected object, and emits X-rays towards the inspected object The detection device includes a first row of detectors and a second row of detectors adjacent to the first row of detectors in the direction of motion of the inspected object. The first row of detectors includes a plurality of detection units with the first energy response, which are arranged on a first plane parallel to the plane of the distributed radiation source to receive an X penetrating the inspected object Ray, the second row detector includes a plurality of detection units with a second energy response, which are arranged on the second plane parallel to the plane of the distributed ray source to receive the X-ray penetrating the inspected object; the acquisition device is connected with the detection device to detect the X-ray detected by the first row detector The ray is converted into a first digital signal, and the X-ray detected by the second row of detectors is converted into a second digital signal; the processing device is connected with the acquisition device, and the CT image of the inspected object is reconstructed based on the first digital signal and the second digital signal.

The current work of Wuhan Aiwei Technology Co., Ltd. is mainly to improve hardware products, debug machine learning model and build cloud platform. The overall equipment is expected to be put into the bank, customs, subway station, logistics warehouse and other scenarios for testing before the end of the year.


 



For more information, please contact Wuhan Aiwei Technology Co., Ltd.

http://www.iwildt.com/




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