GB2441551A

GB2441551A - Method and apparatus for security inspection of liquid articles using radiation

Info

Publication number: GB2441551A
Application number: GB0624581A
Authority: GB
Inventors: Halfeng Hu; Yuanjing Li; Kejun Kang; Zhiqiang Chen; Yinong Liu; Yulan Li; Li Zhang; Wanlong Wu; Ziran Zhao; Xilei Luo; Bin Sang
Original assignee: Tsinghua University; Nuctech Co Ltd
Current assignee: Tsinghua University; Nuctech Co Ltd
Priority date: 2006-09-05
Filing date: 2006-12-08
Publication date: 2008-03-12
Anticipated expiration: 2026-12-08
Also published as: GB0624581D0; GB2441551B

Abstract

Method and apparatus for security inspection of liquid articles using radiation in which a radiation source 10, such as an X-ray or gamma ray source, is arranged to emit radiation for transmission through liquid articles 20 to be inspected, the transmitted radiation being detected by a detector 40. The article to be inspected is rotated relative to the source and detector to allow transmission of radiation through the article and detection of transmitted radiation at a plurality of angles. Environmental information relating to the article, such as the size or material of the package of the article, is also detected by the detector in response to the emitted radiation. A radiation absorption coefficient of the article is calculated from the detected radiation based on the environmental information and the uniformity of the liquid article. The radiation absorption coefficient is compared with preset data to provide information on the composition of the liquid article.

Description

METHOD AND DEVICE FOR SECURITY-INSPECTION OF

LIQUID ARTICLES USING RADIATION

Field of the Invention

The present invention relates to the field of radiation inspection, and particularly, to the method and device for quick security-inspection of liquid articles using radiation.

Background of the Invention

Since 9 * 11 in U.S., security-inspection of aviation is becoming more and more emphasized. Besides traditional security- inspection of packs, security-inspection of the liquid articles carried by passengers is added. Accordingly, means and methods of a quick security-inspection of the liquid articles in packs are in dire need.

Nowadays, there are four types of inspection methods used in security-inspection of liquid articles, including the chemical method, the electromagnetic method, the neutron inspection method and the radiation inspection method, as follows: 1) The chemical method can be subdivided into the odor identification method, the ion scanning explosive inspection method and the substance analysis. The odor identification in practical applications often fails to implement inspection because of sealed and packaged conditions of liquid articles. The ion scanning explosive inspection method is known for its high sensitivity but with high false alarm rate, it suffers from the affection of background environment. The substance analysis is of high precision and high accuracy, but this method needs a certain period of time to analyze the sample, which cannot meet the demands of on-site quick inspection.

2) The electromagnetic method works in an active measurement manner. It distinguishes liquid articles from each other according to their dielectric constants in the electromagnetic field. The electromagnetic method is easily subjected to severe affection of metal packages or other thick material packages. As a result, the electromagnetic method is limited in case of complex package materials.

3) The use of the neutron inspection method will leave residual radiation remaining in the inspected liquid due to the effect of "neutron activation". Furthermore, the radiation shielding is complicate due to neutrons' strong perforation, and the apparatus has to take a large area, so the method is not suitable for application in the security-inspection systems of civil aviation.

4) Currently, most of the security-inspection apparatuses of civil aviation are radiation apparatuses. In these apparatuses, the X-ray 2D imaging technology and the three-dimensional CT technology are mostly adopted. These technologies, which are mainly used for securityinspection of packs, fail to accomplish the security-inspection of liquid articles in packs.

The X-ray 2D imaging technology acquires two-dimensional projection images by integrating three-dimensional infonnation of articles to be inspected along X-ray's direction. These images show difference in the form of grayscale or pseudo-color, to give the operator a vivid display.

However, the X-ray 2D imaging technology is in defect of one-dimensional information of objects, so the inspection of liquid articles suffers from severe affection of shapes and sizes of the liquid articles.

The three-dimensional CT technology is the extension and application of CT technology. The CT technology was applied in the diagnostics first, which was implemented by conducting a multi-angle projection of respective slices of an article. By using a computer to reconstruct the multi-angle projection data of respective slices, reconstructed images were obtained. The information of the different attenuation coefcients in the reconstructed images was displayed in the form of different grayscales, by which the inner differences of the articles were displayed. With the development of the CT technology, the industrial CT for the nondestructive inspection and the package CT for the security-inspection were put into use, with the goal remaining to be acquiring the slice images of the inner difference of articles. Therefore, with the traditional X-ray 3D imaging technology for the liquid articles, only the slice images with no differences can be seen, Thus, it is difficult for the security-inspection devices of the CT type to gain popularity, for their high cost and builciness, as a result of the wide range of the articles that can be inspected by them.

To sum up, for the quick inspection of the liquid articles, the chemical method, the electromagnetic method and the neutron inspection method are not suitable for quick security-inspection. By using the X-ray 2D imaging technology and the three-dimensional CT technology, grayscale images or pseudo color images with contrast are acquired, but these images cannot work as sufficient evidence for the security inspection of the liquid articles.

Summary of the Invention

In order to overcome the disadvantages in the existing technologies, an object of the invention is to provide a method and a device for security-inspection of liquid article using radiation for conducting quick inspections and getting quantitative information of the liquid articles to be inspected without destroying the packages of the liquid articles.

In one aspect, the invention provides a method for security-inspection of liquid articles using radiation, comprising the steps of acquiring initial environmental information; emitting radiation beams to transmit through the liquid articles; receiving the radiation beams transmitted through the liquid articles to generate multi-angle projection data; based on the initial environmental information and the uniformity of the liquid articles, computing a radiation absorption coefficient of the liquid articles using an inverse operation of the multi-angle projection data; and comparing the radiation absorption coefficient predetermined data to get relevant information of the liquid articles.

According to an embodiment of the invention, the initial environmental information comprises geometry boundary information of io the liquid articles to be inspected.

According to an embodiment of the invention, the geometry boundary information was obtained using radiogram technology or scan imaging technology.

According to an embodiment of the invention, the liquid articles to j5 be inspected exhibit uniformity with respect to radiation.

In another aspect, the present invention provides a device for security-inspection of liquid articles using radiation, which comprises the following parts: a radiation source for emitting radiation beams; a carrier mechanism to carry the liquid articles to be inspected so as to allow the radiation beams to be transmitted through; a detection and collection appliance to acquire both initial environmental information and multi-angle projection data of the liquid articles; and a computer data processor.

The computer data processor comprises means of computing a radiation absorption coefficient of the liquid articles using an inverse operation of the multi-angle projection data, the initial environmental information and uniformity of the liquid articles being limiting conditions, and means for comparing the radiation absorption coefficient with predetermined data to get relevant information of the liquid articles.

According to an embodiment of the invention, the radiation source is an X-ray machine (tube) or an isotope source.

According to an embodiment of the invention, there are one or more radiation sources.

According to an embodiment of the invention, the radiation power of the radiation source is adjustable.

According to an embodiment of the invention, the detection and collection appliance is formed by a combination of a detector and a data collector.

According to an embodiment of the invention, the detector is a solid detector, a liquid detector, a gas detector or a semiconductor detector.

According to an embodiment of the invention, there are one or more detectors.

According to an embodiment of the invention, the detector is in a form of one-dimensional array or two-dimensional array.

According to an embodiment of the invention, the detector has a power switching function.

According to an embodiment of the invention, the detector operates in an (current) integral mode or a pulse (counting) mode.

According to an embodiment of the invention, the multi-angle projection data is obtained by rotating the liquid articles to be inspected or rotating the radiation source and the detection and collection appliance.

According to an embodiment of the invention, the multi-angle projection is obtained by increasing the amount of the projection angles or mounting the detector with an offset of 1/4 size of a detector unit.

According to an embodiment of the invention, the computer data processor conducts the comparison by adopting a predetermined identification algorithm.

According to an embodiment of the invention, the coordination of the radiation source, the detection and collection appliance, the carrier mechanism and the computer data processor is controlled by a scan controller.

The device of the invention has the advantages of occupying small area, high accuracy, high safety and reliability, and easy shielding. The present invention is suitable for security-inspection at aviation fields and other important sites.

S

Brief Descrintion of the Drawin2s The features and advantages of the invention can be more clarified from the following detailed descriptions for the accompanying drawings.

Wherein: FIG! is a schematic diagram of an inspection device according to an embodiment of the invention; FIG2 shows a structure diagram of the computer data processor in the inspection device of FIG!; FIG3 shows a flow chart of the inspection methOd according to an embodiment of the invention; and FIG4 shows a functional block diagram of the computer data processor in the inspection device of FIG!.

Detailed Description of the Preferred Embodiments

The preferred embodiment of the invention will now be described more fully hereinafter with reference to the accompanying drawings. In the drawings the same reference numerals are used for denoting the same or similar components that are shown in different figures. For clarity, the detailed description of the known function and structure incorporated herein will be omitted, which would otherwise weaken the subject of the invention.

FIG.! is a schematic diagram of the structures of an inspection device according to an embodiment of the invention.

As shown in Fig.!, the inspection device according to the invention comprises a radiation source 10 for emitting radiation for inspection, e.g. a X-ray machine or a isotope (X-ray or y -ray source) source; a carrier mechanism 30, which carries the liquid articles to be inspected 20, can rotate around axis Z thereof, and can ascend or descend to take the liquid articles 20 into the inspection area, thereby the radiation emitted by the radiation source 10 can transmit through the liquid articles 20; a detection and collection appliance 40, an integrated module of a detector and a data collector, which is used to detect the radiation transmitted through the liquid articles 20 to acquire analog signals, and convert the analog signals into digital signals, and hence output the scanning data of the liquid articles 20; a scan controller 50, which controls each component of whole system so that they operate synchronously; and a computer data processor for processing the data collected by the data collector and outputting inspection results.

As shown in FIG.!, the radiation source 10 is placed at one side of the carrier mechanism 30 carrying the liquid articles to be inspected 20, while the detection and collection appliance 40 is placed at the other side of the carrier mechanism 30. The detection and collection appliance 40 comprises a detector and a data collector for acquiring the initial environmental information and the multi-angle projection data of the liquid articles 20. The data collector has a signal amplifying and formation circuit, which operates under (current) integration mode or pulses (counting) mode. The detection and collection appliance 40 has its data output cable connected with the computer data processor 60 to store the collected data into a database.

FIG.2 shows a structure diagram of the computer data processor 60 of FIG.!. As shown in FIG.2, the data collected by the data collector are stored in the memory 61. The configuration data and programs of the io computer data processor are stored in the ROM (Read Only Memory) 62.

The RAM (Random Access Memory) 63 is used for temporarily storing various data during the operating procedure of the processor 66. Besides, computer programs and a pre-created database are also stored in the memory 61 for data processing. The database stores various relevant parameters of known liquid articles, such as radiation absorption coefficient, density and etc, to compare with the radiation absorption coefficients of the liquid articles 20 computed by the processor 66. There is an internal bus 64 that connects the memory 61, the ROM 62, the RAM 63, the input device 65, the processor 66 and the display device 67 together.

After the user inputs operation commands through the input device such as keyboards and mouse, the instruction code of the computer I0 programs will instruct the processor 66 to perform predetermined data processing algorithm. After the processing results are obtained, they will be displayed on the display device 67 such as LCD, or redirected in the form of a hard copy.

FIG.3 shows the flow chart of an inspection method according to an embodiment of the invention. As shown in FIG.3, at step SlO, the liquid articles to be inspected 20 are placed on the carrier mechanism 30. When an operator sends out the command of starting a scan, the scan controller controls the radiation source 10 to emit radiation, and controls the io carrier mechanism 30 to ascend and descend so as to enter the inspection area constituted by the X-ray source 10 and the detector. At the same time, radiation beams are emitted from the radiation source 10 and transmit through the liquid articles to be inspected 20. The scan controller controls the detection and collection appliance 40 to receive the i radiation transmitted through the liquid articles 20, to acquire initial environmental information of the liquid articles, such as the geometry boundary information, etc.. The geometry boundary information can be obtained by the X-ray radiographic technique or by X-ray scan imaging technology. The X-ray scan imaging technology can adopt translating mode, rotating mode or spiral mode.

Besides, in the above procedures, the obtained initial environmental information of the liquid articles to be inspected 20 contains the size of

II

package, the material of package, the volume ratio of package to liquid articles, and so on. These information and radiation absorption coefficients of various liquid articles can be pre.classified by using neural network recognition algorithm to form a database. In the real inspection procedure, the inspection of the liquid articles 20 is implemented by comparing the measured features with the features in the database.

Thereafter, at step S20, the carrier mechanism 30 rotates under the control of the scan controller 50. When the carrier mechanism 30 reaches the first angle, radiation will be emitted from the radiation source 10 to transmit through the liquid articles to be inspected 20. The detection and collection appliance 40 receives the transmitted radiation to obtain the projection data of the first angle, which is denoted as a 1 xN dimensional vector g1 and stored in the memory 61 of the computer data processor 60, wherein N is the number of the detection units of one row in the detector.

is At step S20', the carrier mechanism 30 continues rotating under the control of the scan controller 50. When the canier mechanism 30 reaches the second angle, radiation will be emitted from the radiation source 10 to transmit through the liquid article 20. The detection and collection appliance 40 receives the transmitted radiation to obtain the projection data of the second angle, which is denoted as 1 xN dimensional vector g and stored in the memory 61 of the computer data processor 60.

The above steps are repeated in this manner. In step S20", the carrier mechanism 30 continues rotating under the control of the scan controller 50. When the carrier mechanism 30 reaches the Mth angle, the projection data for Mth angle is obtained, which is denoted as 1 xN dimensional vector g and stored in the memory 61 of the computer data processor 60. After the above scan procedure, the multi-angle projection data of the liquid articles 20 is obtained, which is denoted as an MxN dimensional vector g. Thereby, the mu1tiang1e projection data of the liquid article to be inspected 20 can be sequentially acquired for one slice.

Herein, in order to increase multi-angle projection data, the amount of angle projection can be increased during the scanning, or the detector is mounted with an oflet of 1/4 size of one detection unit of the detector.

Suppose that the linear attenuating coefficient (the absorption coefficient) of the liquid article to be inspected 20 is expressed as an I-dimensional vector f, wherein I is the dimension of discrete pixels of the liquid article. Based on the interaction between X-ray and substance, according to the Bill's Law, we can get: g1 = exp(-H1f) = exp(-H21) = exp(-HMI) (1) Wherein the 11M each represents an Nx! system matrix, whose element H reflects the contribution of the discrete pixel j in the object image under the corresponding angle, to the signal collected by the nth detector. Es... HM each is a single sparse matrix, which is determined by practical design of the scanning system. For example, these matrices can be determined by pre-computing and then being stored in the memory 61, or through a real time computation according to the temporal system parameters. Thus, the linear attenuating coefficient information of the liquid articles can be obtained through the inverse operation with regard tothefonnula(1).

The inverse operation is an inverse process of normal operation. The process of normal operation is that the original signal emitted by radiation source attenuates when transmitting through the liquid articles 20 and the detector receives the attenuated radiation signal. Accordingly, an inverse operation is to compute the information of radiation attenuation by the liquid articles on the basis of the signal received by the detector.

However, during the inspection procedure of liquid articles, because the inverse operation is an ill-conditioned problem, other information needs to be incorporated, e.g. the geometry boundary information of the liquid articles to be inspected 20, which is obtained at the former step SI 0, so as to improve the validity and stability of the solution.

At step S30, the boundary condition and uniformity condition for the inverse operation are set on the basis of the initial environmental information obtained in step Si 0, which contains the geometry boundary information of the liquid article 20. The space shape of the liquid articles 20 can be expressed as a bounded function. The geometry boundary information of the liquid articles 20 can be determined by the above Xray radiographic technology or X-ray scan imaging technology, thereby the valid active region 0 can be defined, which is f1 =0, for i 0. The introduction of the boundary condition can speed up the solution, and to io some extent ameliorate its ill-condition. Secondly, as the target object of the inspection system is the liquid part, the scanned object can be divided into two parts, i.e. the liquid region and the non-liquid region Q. For the uniformity of the liquid part, f1 = smooth function, for i CZ, will be obtained. The smooth function is characterized by that both the whole i5 variance in the liquid region Q and the local fluctuation in the non-liquid region Q, are limited. The use of the liquid articles' uniformity greatly optlma7es the extraction of the liquid article information, and improves the mbustness of the system.

It is to be noted that the liquid articles having uniformity denotes those solutions, suspending liquids or emulsions that absorb the radiation uniformly. For example, in the above sense, the milk and the pomdge etc are also liquid articles of uniformity, namely, the uniformity of these liquid articles will be exhibited when they absorb the radiation.

Therefore, at step S40, with the geometry boundary condition of the liquid articles 20 being the boundary condition and the uniformity of the liquid articles being the condition of convergence, using the above formula (1), the computer data processor 60 computes to get the radiation absorption coefficient of the liquid article 20. The valid radiation absorption coefficient of the liquid articles then can be worked out on the basis of the obtained statistical characteristics of the pixels within the region.

Thereafter, at step S50, the computer data processor 60 outputs the relevant information of the liquid article to be inspected 20, by comparing the computed radiation absorption coefficient with those of the known liquids in the database. For example, the radiation absorption coefficient of alcohol is -280, if the inspected result for an unknown liquid article falls into the range of -270 to -290, this unknown liquid article in all probability is alcohol. Afterwards, the identification information of the inspected liquid article will be shown on the display device 67 or directly printed out.

At the above step S40, the Bayesian method can be adopted to compute the radiation absorption coefficient of the liquid article 20 with the geometry boundary information and the uniformity as conditions.

Also the non-statistical method can be adopted, wherein first solve the above formula (1) to obtain a preliminary radiation absorption coefficient, then after optimizing using the boundary condition and uniformity, estimate the linear attenuation coefficient of the liquid article 20 on the basis of distribution off1, for i E, to improve the validity and the stability of the computation. The computation of the radiation absorption coefficient with the Bayesian method and the non-statistical method will be described below as examples.

An example of computation of the linear absorption coefficient of liquid article with the Bayesian method: 1. Determine the target function: cb(f) =1,(g;f)+LP(f) (2) Wherein,(g;f)iS a likelihood function determined by the noise characteristics of the collected data P(f) is the metric of the uniformity fort E Q, e.g. P(f) = -v&iance(f)1, is a regulation parameter preset empirically 2. Solve j = [q)(f)] using the numerical optimization method.

During the process of solution, keep f = 0, and i (2; 3. Calculate the probability distribution of f E to get the linear absorption coefficient of the liquid article, e.g. = mean(f)1, = arg An example of computation of the linear absorption coefficient of liquid article with the non-statistic method: 1. Acquire a preliminary estimate of the radiation absorption coefficient f by an analytic method, e.g. filter-back-projection reconstructing method or ART method; 2. Compute the uniformity of f, c =, a) If the preset uniformity demand is satisfied, say, the local variance is lower than a certain threshold, then acquire the absorption coefficient of the liquid article on the basis of the statistical characteristics off such as p meon(f)Ij.

b) If the uniformity demand is not satisfied, then conduct a boundary condition processing and a smoothing processing with regard to the radiation absorption coefficient f to acquire f'. Compare the orthographic projection of the processed I' with the collected data g, analyze the difference between again to reconstruct and modify f, and then return step 2.

During the implementation of the non-statistical method, the operational speed and precision can be adjusted by setting different uniformity demands. In some extreme cases, the absorption coefficient of liquid article can be obtained just by one step, without iteration.

Besides, at the above step S 10, if the liquid article 20 is of a sandwiched structure or layered e.g. it has two layers. The geometry boundary information of these two layers can be obtained using the above method, respectively, then conduct the same subsequent procedures with regard to the liquid article of the respective layers, and finally output the identification information of the two types of liquid articles, which serves as the ultimate identification information of the inspected liquid article 20.

For example, in the case of a two-layer liquid article, the liquid article region comprises the first liquid article region (1i and the second liquid article region D. The linear attenuation coefficient of the first liquid article region O is denoted as fA, the linear attenuation coefficient of the second liquid article region fln is denoted as fB. Then fA=smooth function 1, for AEA, f5=smooth function 2, for BEflIB.

Thus, the above-described step S1C-S5O are conducted with regard to the first liquid article region ii and the second liquid article region 0, respectively.

As mentioned above, based on the information such as the size of package, the material of package, the size ratio of the package to the liquid article, making use of the recognition algorithms such as the ANM (Artificial Neural Network), SVM (Support Vector Machine), BNN (Bayesian Neural Network), a classification table for the known various liquid articles can be established and stored into a database. As stated above, at steps SlO and S40, after acquiring the initial environmental information as well as the radiation absorption coefficient of the liquid article 20, the classification of the liquid article 20 in the database can hence be determined with the same neural network recognition algorithm, thereby the identification information of the liquid article 20 can be obtained.

In this embodiment of the invention, the scanning is implemented by rotating the inspected liquid article 20. By means of scanning, both the volume and the cost of the device are reduced. However, another manner of scanning, that the inspected liquid article 20 stays still while the radiation source 10 with the detection and collection appliance 40 rotates, can also be adopted.

Besides, the radiation source 10 may comprise one or more X-ray machines, as well as one or more isotope sources, and the radiation energy of the X-ray machines is adjustable. In the case that the radiation source 10 comprises a plurality of X-ray machines or isotope sources, there may be the same number of detectors as the X-ray machines or isotope sources, and these X-ray machines or isotope sources are set correspondingly. Herein, the detectors may be gas detectors, liquid detectors, solid detectors or semiconductor detectors, and may have an energy switching function. Besides, the detectors can work under the mode of one-dimensional array or two-dimensional arrays, i.e. the line array detector or the area array detector.

The computation procedure of the radiation absorption coefficient and the acquiring procedure of the identification information of the inspected liquid article 20 are described above in the form that the computer data processor 60 nins the programs containing the predetermined data processing algorithm. However, the computer data processor 60 may be embodied in other forms. FIG4 is a functional block diagram of the computer data processor 60 of the inspection device of FIG!.

As shown in FIG.4, as another example of the computer data processor, this computer data processor 60' comprises the following: a data memory 71, which stores the initial environmental information and the multi-angle projection data and etc, such as the system matrices H HMtO describe the system property; the database 74, which stores the absorption coefficients of various liquid articles or other characteristic information, as well asa database of the classification table of various liquid articles to be used for the comparison of the checking procedure; an absorption coefficient calculation unit 72, which calculates the radiation absorption coefficient of the inspected liquid article 20 based on formula (1), under the condition of uniformity of the liquid article, on the basis of the initial environmental information stored in the data memory 7! such as the geometry boundary information of liquid article, and the multi-angle projection data; a comparison unit 73, which compares the radiation coefficient of the liquid article 20 computed by the absorption coefficient computing unit 72 with those stored beforehand to determine the useful identification information of the liquid article 20; a output unit 75 such as a display or other output device, for presenting the identification infonnation acquired by the comparison unit 73 to the operator.

Although exemplary embodiments of the present invention have been described hereinabove, it should be clear to those skilled in the field that any variations and/or modifications of the basic inventive concepts will still fall within the scope of the present invention, as defined in the appended claimR.

Claims

CLAIMS: I. A method for security-inspection of liquid articles using

radiation comprising the steps of: acquiring initial environmental information; emitting radiation beams to transmit through the liquid articles; receiving the radiation beams transmitted through the liquid articles to form multi-angle projection data; computing a radiation absorption coefficient of the liquid articles using inverse operation of the multi-angle projection data, based on the initial environmental information and the uniformity of the liquid articles; and comparing the radiation absorption coefficient with predetermined data to get relevant information of the liquid articles inspected.
2. The method of claim!, wherein the initial environmental information comprises geometry boundary information of the liquid articles to be inspected.
3. The method of claim 2, wherein the geometry boundary information is obtained by radiographic technology or scan imaging technology.
4. The method of claim 2, wherein the liquid articles to be inspected exhibit uniformity with regard to radiation.
5. A device for security-inspection of liquid articles using radiation comprising: a radiation source (10) for emitting radiation beams; a carrier mechanism (30) for carrying the liquid articles so as to allow the radiation beams to be transmitted through; a detection and collection appliance (40) for acquiring initial environmental information and multi-angle projection data of the liquid articles to be inspected; and a computer data processor (60,60'), wherein the computer data processor (60, 60') comprises: means for computing a radiation absorption coefficient of the liquid articles to be inspected by inverse operation of the multi-angle projection data, the initial environmental information and uniformity of the liquid articles being limiting conditions; and means for comparing the radiation absorption coefficient with predetermined data to get relevant information about the liquid articles inspected.
6. The device of claim 5, wherein the radiation source (10) is an X-ray machine or an isotope source.
7. The device of claim 6, wherein the radiation source (10) is of one ormore.
8. The device of claim 6, wherein the radiation power of the radiation source (10) is adjustable.
9. The device of claim 5, wherein the detection and collection appliance is formed by a combination of a detector and a data collector.
10. The device of claim 9, wherein the detector is a solid detector, a liquid detector, a gas detector or a semiconductor detector.
11. The device of claim 9, wherein the detector is of one or more.
12. The device of claim 9, wherein the detector is in the form of one-dimensional array or two-dimensional array.
13. The device of claim 9, wherein the detector has a power switching function.
14. The device of claim 9, wherein the detector operates under an integration mode or a pulse mode.
15. The device of claim 9, wherein the multi-angle projection data is obtained by rotating the liquid articles to be inspected or rotating the radiation source and the detection and collection appliance.
16. The device of claim 9, wherein the multi-angle projection data is obtained by increasing the number of projection angles or mounting the detector with an offset of 1/4 size of a detector unit.
17. The device of claim 5, wherein the computer data processor conducts the comparison by adopting predetemüned identification algorithm.
18. The device of claim 5, wherein the coordination of the radiation source (10), the detection and collection appliance (40), the carrier mechanism (30) and the computer data processor (60,60') is controlled by a scan controller (50).