System and method for inspecting cargo using multiple energy level radiation

Abstract

The present invention relates to a system (100) and method for inspecting an object using multiple interleaved radiation energy. The system (100) includes a radiation module (30) configured to generate and capture radiation at multiple energy levels to scan contents of a shipment and convert the captured radiation into multiple images; a controller (50) configured for sending signals to the radiation module (30) to start or stop generating radiation and for controlling the energy level and pulse frequency of the radiation generated by the radiation module (30). The system (100) further includes a processor (61) configured for determining whether the shipment contains any contraband by analyzing the multiple images, classifying the shipment based on material type and substance group, and highlighting areas on the analyzed images of the same substance by delineating a perimeter of the object within a material color image for the material.

Description

Technical Field

[0001] This invention relates to a system and method for inspecting objects using multiple staggered radiation energies. More specifically, this invention relates to a system and method for inspecting cargo using radiation at different energy levels to detect contraband. Background Technology

[0002] Imports and exports play a vital role in a nation's economic development and growth. However, not all goods can be imported or exported; therefore, goods illegally imported or exported are considered contraband. Examples of contraband include, but are not limited to, drugs, duty-free cigarettes, and duty-free alcoholic beverages. Therefore, a system and method are needed for inspecting objects to detect contraband and prevent its entry and exit from national borders.

[0003] Generally, goods are imported or exported via freight. To inspect goods in freight shipments, authorities typically use radiographic techniques to streamline the inspection process. During inspection, radiation such as X-rays and gamma rays is generated and emitted from one side of the machine onto the goods in the freight shipment. As the radiation passes through the goods, the goods absorb some of the energy carried by the radiation. The radiation is then received by a detector on the opposite side of the machine. The energy of the radiation is converted into an image and displayed for authorities to view and analyze.

[0004] While many systems and methods exist for inspecting cargo using radiation, most are limited to a single energy level, thus only displaying the physical form of the cargo in grayscale. Grayscale representation lacks material representation. In further improvements, systems and methods using dual-energy-level radiation have been developed.

[0005] Examples of systems and methods for inspecting cargo using dual-energy-level radiation are disclosed in US Patent No. 7,580,505 B2. This patent relates to a method and apparatus for inspecting an object using multi-energy radiation. The method includes interacting multi-energy radiation with the object under inspection, detecting and recording the detection values ​​after the interaction of the multi-energy radiation with the object, and substituting a portion of the detection values ​​into a predetermined calibration function to obtain information. The information includes primary material properties. Further material properties of the object are determined by applying a set of functions suitable for the energy bands corresponding to the information.

[0006] Another example is disclosed in U.S. Patent No. 10,641,918 B2, which relates to methods, apparatus, and systems for cargo inspection. This system utilizes a technique of extracting two X-ray pulses with lower and higher energies within a single beta accelerator acceleration cycle.

[0007] However, such systems and methods can only classify the materials of goods. For example, they can only detect whether a shipment contains solid or liquid goods, but cannot further classify whether liquid goods are alcohol-based. Therefore, these systems and methods still lack precision and accuracy in identifying substances that are contraband. This can lead to misidentification of contraband in shipments. Therefore, a system and method that addresses these problems is needed. Summary of the Invention

[0008] This invention relates to a system (100) and method for inspecting cargo using multi-energy-level radiation. The system (100) includes a radiation module (30) having a radiation source submodule (31) and a data acquisition submodule (32); and a controller (50) connected to the radiation module (30). The radiation source submodule (31) is configured to generate radiation emitted toward the cargo, and the data acquisition submodule (32) is configured to capture the radiation emitted from the radiation source submodule (31). The controller (50) is configured to trigger the radiation source submodule (31) to start and stop generating radiation and to control the energy level and pulse frequency of the radiation generated by the radiation source submodule (31). The system (100) is characterized in that the radiation source submodule (31) is further configured to sequentially generate radiation at at least three different energy levels; and the data acquisition submodule (32) is further configured to capture radiation at at least three different energy levels, convert the captured radiation into an image for each energy level, wherein each pixel value in each image represents the transmittance of the captured radiation at at least three different energy levels. Furthermore, the radiation module (30) also includes a data storage (33) connected to the radiation source submodule (31). The data storage (33) is configured to store setup data and lookup tables for generating radiation at at least three different energy levels by the radiation source submodule (31), wherein the setup data includes the number of energy levels of the radiation, the value of the energy level of the radiation, and the pulse frequency of the radiation, and wherein the lookup tables contain extended phase timing values. The system (100) also includes a server (60) connected to the radiation module (30), wherein the server (60) has a processor (61) configured to determine whether the cargo contains any contraband by analyzing the image of each energy level.

[0009] Preferably, at least three energy levels of the radiation are in the range of 2.0 MeV to 9.0 MeV, and the pulse frequency is between 300 Hz and 500 Hz.

[0010] Preferably, the system (100) further includes a radioactivity detection module (10) configured to determine whether the cargo contains any radioactive material, and wherein the radioactivity detection module (10) is connected to a server (60) to notify the server (60) whenever radioactive material is detected in the cargo.

[0011] Preferably, the system (100) further includes a weight sensing module (20) configured to determine the presence of a vehicle carrying the freight based on the weight and number of axles of the freight, and wherein the weight sensing module (20) is connected to a server (60) and a controller (50) to trigger the radiation module (30) to start or stop scanning the freight.

[0012] Preferably, the weight sensing module (20) includes at least one pair of strip sensors placed on the surface of the road path to weigh vehicles carrying cargo.

[0013] Preferably, the weight sensing module (20) includes a scale (20m) configured to detect the presence of the freight and measure its weight.

[0014] Preferably, the system (100) further includes a display module (90) connected to the server (60), wherein the display module (90) is configured to display the analyzed image, data from the radioactivity detection module (10) and the weight sensing module (20).

[0015] Preferably, the radioactivity detection module (10), weight sensing module (20), and radiation module (30) are installed along the road path traveled by the freight vehicle.

[0016] The method for inspecting cargo using multi-energy-level radiation includes the following steps: radiation at at least three energy levels is continuously generated by a radiation source submodule (31), the radiation is captured by a data acquisition submodule (32) and the captured radiation is converted into multiple images based on the number of energy levels, the material type of the cargo is determined by a processor (61) through analysis of the multiple images, and the substance type of the cargo is determined by the processor (61).

[0017] Preferably, the step of the radiation source submodule (31) successively generating radiation at at least three energy levels includes obtaining setting data of the radiation energy levels from the data memory (33), wherein the setting data includes the number of radiation energy levels, the pulse frequency of the radiation, the injection current to the acceleration chamber (41), and the magnetic field value provided to the rear magnetic circuit (45) and the extended winding (46), as well as the voltage provided by the radiation source submodule (31) to the high-voltage injection unit (42). In this regard, the radiation source submodule (31) obtains the extended phase timing value corresponding to each energy level from the data memory (33), wherein the extended phase timing value is based on the magnetic flux, the injection current of the extended winding (46), the voltage of the extended winding (46), and the physical orbital radius and geometry of the acceleration chamber (41). Subsequently, the high-voltage injection unit (42) injects pre-accelerated electrons into the acceleration chamber (41). Once the radiation source submodule (31) receives the energy level flag, it determines the value of the energy level to be generated based on the energy level signal contained in the energy level flag. The power supply unit (31a) and the pulse converter unit (31c) supply current pulses to the contraction winding (47) according to the current value obtained from the data memory (33) to generate radiation with a dose rate determined by the setting data from the data memory (33), and supply current pulses to the extension winding (46) according to the current value obtained from the data memory (33) to generate radiation according to the energy level indicated in the energy level signal.

[0018] Preferably, the step of capturing radiation by the data acquisition submodule (32) and converting the captured radiation into multiple images based on the number of energy levels includes receiving energy level signals from the radiation source submodule (31) and the controller (50), such that the first energy level signal includes a low voltage and subsequent energy level signals include a high voltage, capturing radiation with a specific energy level from the radiation source submodule (31) and converting the captured radiation pulse into a scan line for each energy level image, and compiling multiple scan lines with the same energy level to form multiple images.

[0019] Preferably, the step of determining the material type of the cargo by the processor (61) through analysis of multiple images includes performing signal conditioning, selecting a pair of energy levels as a first-level filter for material classification, wherein one energy level is represented as a high energy level and the other as a low energy level. Then, the normalized high-energy-level transmittance for each pixel of the image generated for the high-energy level, the normalized low-energy-level transmittance for each pixel of the image generated for the low-energy level, and the calculation of a function value for each pixel, where the function value is the ratio of the high-energy-level transmittance to the low-energy-level transmittance. The function values ​​of all pixels are plotted on a pre-generated material classification curve, wherein the material classification curve for each material is generated by plotting the function values ​​of a sample material on a graph. The pixel values ​​of the object are classified into material groups based on the proximity of the function values ​​plotted on the pre-generated material classification curve to the trend line of the material.

[0020] Preferably, the step of determining the material type of the object by the processor (61) includes selecting two pairs of energy level combinations as a second energy level filter for material verification, wherein one pair of energy levels is referred to as the first energy level pair and the other pair of energy levels is referred to as the second energy level pair. The function value for each pixel against both the first and second energy level pairs is then calculated and plotted on a plurality of pre-generated material groups, wherein each material group is generated by plotting the function values ​​of the first and second energy level pairs of the sample material on a graph. The pixel values ​​of the object are classified into the corresponding material group based on the proximity of the function values ​​of the first and second energy level pairs to the center of each material group. Attached Figure Description

[0021] The accompanying drawings, which are included in and form part of this specification, illustrate embodiments of the invention and, together with the specification, serve to explain the principles of the invention.

[0022] Figure 1 A block diagram of a system (100) for inspecting cargo using multi-energy level radiation according to an embodiment of the present invention is shown.

[0023] Figure 2(ab) illustrates Figure 1 Perspective and front view of the radiation module (30) of the system (100).

[0024] Figure 3(ae) illustrates Figure 1 Example of the installation setup of the weight sensing module (20) of the system (100).

[0025] Figure 4 An example of the installation setup of the weight sensing module (20) of the system (100) in an alternative embodiment of the present invention is illustrated.

[0026] Figure 5 The diagram shows Figure 1 A block diagram of the radiation source submodule (31) of the radiation module (30) of the system (100).

[0027] Figure 6(ab) illustrates Figure 5 A cross-sectional view of the radiator (40) of the radiation source submodule (31).

[0028] Figure 7 The illustration shows a flowchart of a method for inspecting cargo using multi-energy level radiation according to an embodiment of the present invention.

[0029] Figure 8 The illustration shows a flowchart of the sub-steps for generating radiation at multiple energy levels according to an embodiment of the present invention.

[0030] Figure 9 A flowchart illustrating the sub-steps for determining the type of materials and substances for freight transport according to an embodiment of the present invention is shown. Detailed Implementation

[0031] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. In the following description, well-known functions or structures will not be described in detail because unnecessary details would obscure the description.

[0032] Original Reference Figure 1 The diagram illustrates a block diagram of a system (100) for inspecting freight using multi-energy level radiation according to an embodiment of the present invention. The system (100) is used to scan freight carried by vehicles such as vans and trucks. The system (100) includes a radioactivity detection module (10), a weight sensing module (20), a radiation module (30), a controller (50), a server (60), and a display module (90). The radioactivity detection module (10), the weight sensing module (20), and the radiation module (30) are installed along the road path traversed by the vehicle carrying the freight, which is automatically scanned as it passes through the road path. The area emitting multi-energy level radiation onto the freight is called the detection area.

[0033] The radioactivity detection module (10) is configured to determine whether the cargo contains any radioactive material. The radioactivity detection module (10) is preferably installed at the entrance of the road route. The radioactivity detection module (10) is connected to a server (60) to notify the server (60) whenever radioactive material is detected in the cargo.

[0034] The weight sensing module (20) includes at least one pair of strip sensors placed on the surface of the road path to weigh the vehicle as it travels over the strip sensors, wherein each strip sensor in a pair is placed adjacent to each other. Preferably, the weight sensing module (20) is a dynamic weighing device. The weight sensing module (20) is configured to determine the presence of a vehicle carrying cargo by measuring the weight and detecting the number of axles of the vehicle carrying cargo. If the weight sensing module (20) includes more than one pair of strip sensors, the weight sensing module (20) averages the weight detected by each pair of strip sensors to calculate the total weight of the vehicle carrying cargo. The weight sensing module (20) detects the number of axles of the vehicle carrying cargo by counting the number of times the tires of the vehicle carrying cargo travel over the strip sensors. Typically, different axles of the vehicle carrying cargo have different weights. The weight detection module (20) sums the weights detected for each axle as the total weight of the vehicle carrying cargo. The weight detection module (20) is connected to a server (60), thereby sending the total weight of the vehicle carrying cargo to the server (60) for processing. The detection of weight and number of axles is to prevent objects from being mistaken for vehicles carrying freight or partially freight. As a result, this detection prevention system (100) scans for objects other than the freight or vehicle itself.

[0035] The weight sensing module (20) is also connected to the controller (50) to trigger the radiation module (30) to start or stop scanning the cargo. If any or both strip sensors in the pair are triggered and the weight of the cargo exceeds a threshold weight, the weight sensing module (20) sends a signal to the controller (50) to trigger the radiation module (30). When a strip sensor is not triggered within a predetermined time period, the weight sensing module (20) also sends a signal to the controller (50) to stop the radiation module (30) from scanning the cargo. The predetermined time period is suitably the time period of an electrical relay signal. Thus, the weight sensing module (20) prevents the radiation module (30) from being erroneously activated or deactivated.

[0036] If the weight sensing module (20) includes multiple pairs of strip sensors, the weight sensing module (20) can also be configured to adapt to detection from one pair of strip sensors to send a signal to start scanning freight, and to adapt to detection from another pair of strip sensors to send a signal to stop scanning freight. In this case, at least one pair of strip sensors is installed on the road path before the detection area, while the other pair of strip sensors is installed on the road path after the detection area.

[0037] If more than one pair of strip sensors are installed before the detection area, the weight sensing module (20) sends a signal to begin scanning whenever a vehicle's tires trigger any pair of strip sensors, based on the preferences of the authorities (e.g., customs). In this case, each pair of strip sensors is placed at a certain distance, such that one pair of strip sensors has time to detect the tires of the vehicle carrying cargo and send the detected weight to the server (60) before another pair of strip sensors detects the tires of the vehicle carrying cargo. This distance between one pair of strip sensors and another pair of strip sensors is calculated based on the speed limit for vehicles carrying cargo traveling through the road path.

[0038] Below is an example of the installation setup of the strip sensor of the weight sensing module (20) on a road path. An example of the installation setup is illustrated in Figure 3(ae), where the detection area is indicated by dashed lines.

[0039] Figure 3(a) illustrates a first example of the installation setup of a pair of strip sensors (20a) located before the detection area. In this example, the weight sensing module (20) includes a pair of strip sensors (20a) installed in an alternating configuration. When either of the strip sensors (20a) detects a tire carrying cargo, the weight sensing module (20) sends a signal to the controller (50) to activate the radiation module (30). Whenever neither of the two strip sensors (20a) detects any tire within a predetermined time period, the weight sensing module (20) also sends a signal to the controller (50) to deactivate the radiation module (30).

[0040] Figure 3(b) shows a second example of the installation setup of two pairs of strip sensors (20b, 20c), referred to as the first pair of strip sensors (20b) and the second pair of strip sensors (20c). The first pair of strip sensors (20b) is installed before the detection area, while the second pair of strip sensors (20c) is installed after the detection area. When the first pair of strip sensors (20b) simultaneously detects a tire carrying cargo, the weight sensing module (20) sends a signal to the controller (50) to activate the radiation module (30). After the second pair of strip sensors (20c) stops detecting new tire pairs within a predetermined time period, the weight sensing module (20) sends a signal to the controller (50) to stop the radiation module (30).

[0041] Figure 3(c) shows a third example of the installation setup of two pairs of strip sensors (20d, 20e), wherein the two pairs of strip sensors (20b, 20c) are referred to as the third pair of strip sensors (20d) and the fourth pair of strip sensors (20e). Both pairs of strip sensors (20d, 20e) are installed before the detection area, wherein the fourth pair of strip sensors (20e) is closer to the detection area than the third pair of strip sensors (20d). If the authorities want to inspect the entire freight (including the head of the vehicle carrying the freight), the weight sensing module (20) is configured to send a signal to trigger the radiation module (30) when the third pair of strip sensors (20d) initially detect the tires of the vehicle simultaneously. On the other hand, if the authorities only want to inspect the contents of the freight, the weight sensing module (20) is configured to send a signal to trigger the radiation module (30) whenever the fourth pair of strip sensors (20e) initially detects the tires of the freight simultaneously. However, after the third pair of strip sensors (20d) stops detecting any tires within a predetermined time period, the weight sensing module (20) sends a signal to the controller (50) to stop the radiation module (30).

[0042] Figure 3(d) shows a fourth example of the installation setup of three pairs of strip sensors (20f, 20g, 20h), wherein the three pairs of strip sensors (20f, 20g, 20h) are referred to as the fifth pair of strip sensors (20f), the sixth pair of strip sensors (20g), and the seventh pair of strip sensors (20h). The fifth pair of strip sensors (20f) is installed before the detection area, while the other two pairs of strip sensors (20g, 20h) are installed after the detection area. The sixth pair of strip sensors (20g) is installed closer to the detection area than the seventh pair of strip sensors (20h). When the fifth pair of strip sensors (20f) initially detects the tires of the cargo simultaneously, the weight sensing module (20) sends a signal to trigger the radiation module (30). When the cargo leaves the system (100) and the sixth pair of strip sensors (20g) stops detecting any tires within a predetermined time period, the weight sensing module (20) sends a signal to the controller (50) to stop the radiation module (30).

[0043] Figure 3(e) shows a fifth example of the mounting arrangement of four pairs of strip sensors (20i, 20j, 20k, 20l), which are referred to as the eighth pair (20i), the ninth pair (20j), the tenth pair (20k), and the eleventh pair (20l). The eighth and ninth pairs of strip sensors (20i, 20j) are mounted before the detection area, while the tenth and eleventh pairs (20k, 20l) are mounted after the detection area. Compared to the ninth pair (20j), the eighth pair (20i) is mounted further away from the detection area. On the other hand, compared to the eleventh pair (20l), the tenth pair (20k) is mounted closer to the detection area.

[0044] If the authorities intend to inspect the entire freight shipment, including the head of the vehicle carrying the freight, the weight sensing module (20) sends a signal to trigger the radiation module (30) when the eighth pair of strip sensors (20i) initially detect the tires of the freight shipment simultaneously. Conversely, if the authorities only intend to inspect the contents of the freight shipment, the weight sensing module (20) sends a signal to trigger the radiation module (30) when the ninth pair of strip sensors (20j) initially detect the tires of the freight shipment simultaneously. However, after the tenth pair of strip sensors (20k) stops detecting any tires within a predetermined time period, the weight sensing module (20) sends a signal to the controller (50) to stop the radiation module (30).

[0045] In an alternative embodiment, the weight sensing module (20) includes a scale (20m) installed along the road path before the detection area, such as Figure 4 As shown. A scale (20m) is used to detect the presence of freight and measure its weight to identify the freight based on its weight. The weight sensing module (20) sends a signal to trigger the radiation module (30) after the scale (20m) detects the presence of freight and determines that the weight of the freight exceeds a threshold weight to prevent erroneous activation of the radiation module (30).

[0046] The radiation module (30) is connected to the controller (50) and the server (60). The radiation module (30) is primarily configured to generate and capture radiation at multiple energy levels to scan the contents of the cargo. The radiation module (30) also includes a radiation source submodule (31), a data acquisition submodule (32), and a data storage device (33).

[0047] The radiation source submodule (31) is configured to successively generate radiation at multiple energy levels to inspect the contents of the cargo. Specifically, the radiation source submodule (31) successively generates radiation at at least three different energy levels. The radiation source submodule (31) can be a beta accelerator, a linear accelerator, an X-ray generator, etc. The radiation source submodule (31) generates X-ray radiation with energy levels between 2.0 MeV and 9.0 MeV. Preferably, the energy level of the radiation is increased by 0.5 MeV. Furthermore, preferably, the radiation has a pulse frequency between 300 Hz and 500 Hz, thus the optimal pulse frequency for each radiation at one energy level is approximately 400 Hz. Therefore, the radiation frequency with four energy levels is 100 Hz.

[0048] refer to Figure 5 The diagram shows a block diagram of a radiation source submodule (31), which includes a radiator (40), a power supply unit (31a), and a pulse converter unit (31c). The radiator (40) is electrically connected to the power supply unit (31a) and the pulse converter unit (31c).

[0049] The radiator (40) is a circulating accelerator in which electrons move along a circular trajectory to gain enough energy to disrupt the eddy field and produce radiation at multiple energy levels. Figure 6(ab) shows a cross-sectional view of the radiator (40). The radiator (40) includes an acceleration chamber (41) with a high-voltage injection unit (42), magnetic poles (43), a main winding (44), a back magnetic circuit (45), an extension winding (46), and a contraction winding (47).

[0050] The radiator (40) is preferably assembled in such a manner that the acceleration chamber (41) is located above the main winding (44), the extension winding (46), and the contraction winding (47). The acceleration chamber (41) is suitably annular in shape. Furthermore, the laminated insert is preferably mounted at the center of the acceleration chamber (41), while the magnetic pole (43) is preferably mounted below the laminated insert. The extension winding (46) surrounds the magnetic pole (43), while the contraction winding (47) surrounds the extension winding (46). The main winding (44) surrounds the contraction winding (47), and then the magnetic circuit (45) forms the outer edge of the radiator (40) and surrounds the acceleration chamber (41) and the main winding (44).

[0051] The high-voltage injection unit (42) includes a thermionic cathode and a terminal anode, wherein the high-voltage injection unit (42) is configured to inject pre-accelerated electrons into the acceleration chamber (41). The thermionic cathode pre-accelerates the electrons to an energy of 40 keV before they are injected into the equilibrium orbit region within the acceleration chamber (41). The high-voltage injection unit (42) is also configured to emit radiation toward the data acquisition submodule (32) via the terminal anode.

[0052] A magnetic pole (43) is mounted below the accelerator chamber (41), wherein the magnetic pole (43) is suitably circular in shape. The magnetic pole (43) generates a magnetic field that provides motion for electrons orbiting a circle near their equilibrium orbit within the accelerator chamber (41). The magnetic pole (43), together with the antimagnetic circuit (45) and the current supplied to the main winding (44) by the power supply unit (31a), generates an eddy current field. The eddy current field, together with the magnetic field, accelerates the electrons. Thus, as the electrons move along the circular orbit of the accelerator chamber (41), their energy increases with each rotation.

[0053] The extension winding (46) is configured to provide electron extension to the internal target. The extension winding (46) is electrically connected to the power supply unit (31a) to receive current pulses supplied by the pulse converter unit (31c) and increase the radius of electron motion in the acceleration chamber (41). Electrons move along the extension spiral and collide with the target placed on the terminal anode of the high-voltage injection unit (42). As the electrons decelerate in the target, their kinetic energy is converted into the energy level of radiation that leaves the terminal anode of the high-voltage injection unit (42) and moves toward the data acquisition submodule (32). Therefore, the energy level of the radiation is controlled based on the current pulses supplied by the pulse converter unit (31c) to the extension winding (46).

[0054] The contraction winding (47) is configured to control the radiation dose rate generated by the radiation source module (31) by controlling the number of electrons captured by the terminal anode. The contraction winding (47) is electrically connected to the power supply unit (31a), whereby the power converter (42) supplies current pulses to the contraction winding (47). When current flows through the contraction winding (47), the contraction winding (47) generates an auxiliary pulsed magnetic field that alters the instantaneous state of the equilibrium orbit of the acceleration chamber (41). The auxiliary pulsed magnetic field also alters the morphology of the magnetic field in the radiator (40). As a result, the radiation dose rate can be changed based on the current pulses supplied by the pulse converter unit (31c).

[0055] The pulse converter unit (31c) is connected to the radiator (40) and the power supply unit (31a). The pulse converter unit (31c) is configured to convert the AC power received from the power supply unit (31a) into DC power, control the voltage supplied to the high voltage injection unit (42), and control the current pulses supplied to the extension winding (46) and the contraction winding (47).

[0056] A power supply unit (31a) is configured to supply power to the radiator (40), wherein the power supply unit (31a) includes multiple capacitor banks (not shown) and an energy storage capacitor filter (not shown). Each capacitor bank is configured to store approximately 860 volts of electrical energy and supply electrical energy to the radiator (40) during the scanning process. The energy storage capacitor filter is configured to store electrical energy from the pulse converter unit (31c) during periods of excess energy and release the stored electrical energy during periods of insufficient energy to provide smooth DC power to the radiator (40).

[0057] Return to reference Figure 1 The data acquisition submodule (32) is configured to capture and measure multi-energy level radiation emitted from the radiation source submodule (31). Furthermore, the data acquisition submodule (32) converts the multi-energy level radiation into multiple images, such that the value of each pixel in each image corresponds to the exact point of the cargo being inspected. The data acquisition submodule (32) generates an image for each energy level, thus generating four images corresponding to the number of radiation energy levels if four radiation energy levels exist. Furthermore, each pixel value in each image represents the transmittance of the multi-energy level radiation. The data acquisition submodule (32) connects to the server (60) to send the images to the server (60) for processing and analysis.

[0058] The data acquisition submodule (32) is connected to the radiation source submodule (31) and the controller (50). The data acquisition submodule (32) receives signals from the radiation source submodule (31) and the controller (50). The data acquisition submodule (32) compares the signals received from the radiation source submodule (31) and the server (50) to synchronize the radiation source submodule (31) with the data acquisition submodule (32).

[0059] The data acquisition submodule (32) includes multiple detectors capable of capturing bremsstrahlung radiation at different energy levels. As shown in Figure 2(ab), the multiple detectors are preferably positioned within the gate, along the top and one side of the gate and on the opposite side of the gate opposite the radiation source submodule (31). The multiple detectors are aligned to capture radiation emitted from the radiation source submodule (31) at different angles. As the freight is driven through the gate, the multiple detectors are able to capture radiation passing through the freight at different angles to cover each area of ​​the freight.

[0060] The data storage (33) is configured to store setup data for multi-energy-level radiation, including but not limited to the number of energy levels of radiation, the value of the energy level of radiation, the injection current setting, and the pulse frequency of radiation. The data storage (33) also stores a lookup table containing extended phase timing values. The extended phase timing values ​​are calculated based on the magnetic flux, the injection current of the extended winding (46), the voltage of the extended winding (46), and the physical orbital radius and geometry of the acceleration chamber (41).

[0061] The controller (50) is connected to the weight sensing module (20), the radiation source submodule (31), and the data acquisition submodule (32). The controller (50) is configured to trigger the radiation source submodule (31) to start and stop generating radiation and to control the energy level and pulse frequency of the radiation generated by the radiation source submodule (31). The controller (50) triggers the radiation source submodule (31) to start and stop generating radiation based on the signal received from the weight sensing module (20).

[0062] The controller (50) is configured to send energy level flags to the radiation source submodule (31), wherein each energy level flag includes a trigger signal and an energy level signal. The trigger signal is used to initiate or stop the radiation generation of the radiation source submodule (31). The energy level signal is used to indicate the energy level of the radiation. The controller (50) sends a first energy level flag to the radiation source submodule (31) to indicate that the radiation source submodule (31) generates radiation with the highest energy level, thus different from other energy level flags; the first energy level flag includes a low voltage energy level signal. On the other hand, subsequent energy level flags include a high voltage energy level signal. The controller (50) sends subsequent energy level flags to the radiation source submodule (31) to indicate that the radiation source submodule generates radiation with subsequent energy levels. The controller (50) sends the same energy level signal to the data acquisition submodule (32) so that the data acquisition submodule (32) can be synchronized with the radiation source submodule (31).

[0063] The server (60) is connected to the radioactivity detection module (10), the weight sensing module (20), the data acquisition submodule (32), and the display module (90), wherein the connection can be wired or wireless. The server (60) receives data from the radioactivity detection module (10) and the weight sensing module (20) and forwards the data to the display module (90). The server (60) also sends analyzed images to the display module (90) for display.

[0064] The server (60) includes a processor (61) configured to analyze data received by the server (60). The processor (61) is also configured to classify cargo based on the type of material. Examples of material types are organic matter, intermediate mixtures of organic and inorganic matter, inorganic matter, and heavy metals. Each material type is represented by a different color in the image. The processor (61) is also configured to further classify cargo into its material group to determine whether the cargo is contraband. The processor (61) highlights areas of the same material in the image by defining the perimeter of the object within the pseudo-color image for the material.

[0065] The display module (90) includes at least one screen, preferably installed in a control room at a remote location. The display module (90) is configured to display data from the radioactivity detection module (10) and the weight sensing module (20) and to display analyzed images. Based on the analyzed images, authorities can conduct further inspections of the cargo.

[0066] Now for reference Figure 7 The diagram illustrates a flowchart of a method for inspecting cargo using multi-energy level radiation according to an embodiment of the present invention. Initially, as in step 1100, a weight sensing module (20) detects the presence of the cargo. The weight sensing module (20) confirms the presence of the cargo before sending a signal to the controller (50). The weight sensing module (20) confirms the presence of the cargo when a pair of strip sensors detect the tires of the cargo. The weight sensing module (20) then further confirms the presence of the cargo by comparing the weight detected by the weight sensing module (20) with a threshold weight of the cargo. If the weight of the cargo exceeds the threshold weight, the weight sensing module (20) sends a signal to the controller (50). If the weight detected by the weight sensing module (20) does not exceed the threshold weight, the weight sensing module (20) considers it a false detection and discards the detection.

[0067] Regarding this, as in step 1200, the weight sensing module (20) detects the total weight of the cargo and the number of axles of the cargo. Whenever a pair of new tires encounters a pair of belt sensors, the weight sensing module (20) treats it as an axle and detects the pressure exerted by the tires on the belt sensors. The weight sensing module (20) sums the pressures exerted by all the tires of the cargo and calculates the total weight of the cargo. If the weight sensing module (20) includes more than one pair of belt sensors, the weight sensing module (20) averages all the weights detected by the belt sensors to obtain the total weight of the cargo.

[0068] As in step 1300, the radioactivity detection module (10) determines whether the cargo shipment contains any radioactive material. The radioactivity detection module (10) sends the detection results to the server (50) for forwarding to the display module (90). As in step 1900, if the radioactivity detection module (10) identifies that the cargo shipment contains radioactive material, the server (50) sends a notification to the display module (90) for the authorities' attention.

[0069] In step 1400, the controller (50) sends an energy level flag to the radiation source submodule (31) for the radiation source submodule (31) to begin sequentially generating radiation at multiple alternating energy levels. Preferably, the radiation source submodule (31) generates X-ray radiation at at least three energy levels with alternating stepped pulse radiation. Preferably, the radiation source submodule (31) generates radiation with an energy level between 2.0 MeV and 9.0 MeV, whereby the energy level of the radiation increases by 0.5 MeV and has a pulse frequency between 300 Hz and 500 Hz. (The remaining text appears to be unrelated and possibly a separate paragraph.) Figure 8 Further explanation of the sub-steps used to generate radiation at multiple energy levels.

[0070] In step 1500, the data acquisition submodule (32) captures radiation and converts the captured radiation into multiple images based on the number of energy levels. The value of each pixel in each image corresponds to the exact point of the cargo being inspected. Furthermore, each pixel value in each image represents the transmittance of the multi-energy-level radiation.

[0071] To ensure that the data acquisition submodule (32) converts the captured radiation into an accurate image for a specific energy level, the data acquisition submodule (32) must be synchronized with the radiation source submodule (31). Therefore, the radiation source submodule (31) forwards the energy level signal from the energy level flag to the data acquisition submodule (32). The controller (50) also sends the same energy level signal to the data acquisition submodule (32).

[0072] Once the data acquisition submodule (32) receives energy level signals from the radiation source submodule (31) and the controller (50), it determines the energy level of the radiation to be received. After capturing radiation, the data acquisition submodule (32) converts the captured radiation pulse into a scan line for an image at a specific energy level. In this regard, the data acquisition submodule (32) determines whether any new energy level indications have been received from the radiation source submodule (31). The data acquisition submodule (32) repeats the process of capturing subsequent radiation pulses and converting the radiation into a scan line for an image at each energy level. Subsequently, the data acquisition submodule (32) compiles scan lines with the same energy level to form a cargo image for a specific energy level. The data acquisition submodule (32) repeats the step of compiling scan lines with the same energy level until it forms a cargo image corresponding to each energy level generated by the radiation source module (31). The cargo image for each energy level is transmitted to the server (60) for processing.

[0073] The server (60) receives images from the data acquisition submodule (32). Subsequently, as in step 1600, the processor (61) analyzes the images to determine the type of materials and substances in the shipment. The sub-step of the processor (61) determining the type of materials and substances in the shipment will be discussed later. Figure 9 Further explanation. Based on the analyzed data, the processor (61) determines whether the shipment contains any contraband. As a result of the analysis, the processor (61) generates an image known as the analyzed image, in which the processor (61) highlights object regions with the same material by defining the perimeter of the object within a pseudo-color image for the material.

[0074] Finally, the server (60) sends the analyzed image to the output module (90) for display to the authorities, as in step 1700. The authorities can use the analyzed data displayed by the output module (90) to detect the cargo carried by the vehicle.

[0075] Figure 8 The diagram illustrates the use of in Figure 7 The flowchart of step 1400 of the method for generating radiation at multiple energy levels is as follows: Initially, as in step 1401, the radiation source submodule (31) obtains setting data for a specific energy level of radiation from the data memory (33). The setting data includes, but is not limited to, the number of energy radiation levels, the energy level value of the radiation, the pulse frequency of the radiation, the injection current of the acceleration chamber (41), the magnetic field value supplied to the rear magnetic circuit (45) and the extended winding (46), and the voltage value to be supplied to the high-voltage injection unit (42).

[0076] As in step 1402, the radiation source submodule (31) also obtains the extended phase timing value corresponding to each energy level from the data memory (33). Preferably, the extended phase timing value f(t) is calculated based on the following equation:

[0077]

[0078] in I represents the magnetic flux, V represents the injected current of the extended winding (46), D represents the voltage of the extended winding (46), and D represents the physical orbital radius and geometry of the acceleration chamber (41).

[0079] As in step 1403, based on the voltage value obtained from the data source (33), the high-voltage injection unit (42) then injects pre-accelerated electrons into the acceleration chamber (41). The electrons move along the acceleration chamber (41) based on the motion provided by the magnetic poles (43) near the equilibrium track in the acceleration chamber (41). The electrons are also accelerated by the eddy electric fields generated by the main winding (44) and the rear magnetic circuit (45) and the magnetic field of the magnetic poles (43).

[0080] Regarding this, as in decision 1404, the radiation source submodule (31) waits until it receives an energy level flag from the controller (50). As in step 1405, once the radiation source submodule (31) receives the energy level flag, the radiation source submodule (31) determines the energy level value of the radiation to be generated based on the energy level signal contained in the energy level flag.

[0081] As in step 1406, the power supply unit (31a) and the pulse converter unit (31c) then supply current pulses to the contraction winding (47) according to the current value obtained from the data memory (33) to generate radiation with a dose rate determined by the setting data from the data memory (33). As the current pulses flow through the contraction winding (47), the contraction winding (47) generates an auxiliary pulsed magnetic field. The auxiliary pulsed magnetic field alters the instantaneous state of the equilibrium orbit and morphology of the magnetic field of the radiator (40).

[0082] Subsequently, as in step 1407, the power supply unit (31a) and the pulse converter unit (31c) provide current pulses to the extended winding (46) according to the current value obtained from the data memory (33) to generate radiation according to the energy level indicated in the energy level signal. The extended winding (46) increases the radius of the electron's movement in the acceleration chamber (41). As the electron moves along the unfolding spiral inside the acceleration chamber (41), it decelerates and impacts a target placed on the terminal node of the high-voltage unit (42). The electron's kinetic energy is converted into the energy level of the radiation. The electron then leaves the radiator (40) and heads toward the data acquisition submodule (32), thereby having the energy level indicated in the energy level signal.

[0083] The radiation source submodule (31) sends an energy level signal to the data acquisition submodule (32) to synchronize the data acquisition submodule (32) with the radiation source submodule (31). Regarding this, as in step 1408, the radiation source submodule (31) determines whether the radiator (40) has reached an equilibrium state for emitting the highest radiation dose rate by evaluating the equilibrium trajectory and instantaneous state of the magnetic field and morphology of the radiator (40). Only if the radiator (40) has not reached an equilibrium state for emitting the highest radiation dose rate does the radiation source submodule (31) search for other combinations of injected current values ​​and current pulse values ​​for the contraction winding (47). The new combinations of injected current values ​​and current pulse values ​​for the contraction winding (47) are stored in the data memory (33) for use in the next trigger cycle.

[0084] As in step 1409, the radiation source submodule (31) determines whether it has received any new energy level flag from the controller (50). If the radiation source submodule (31) receives a new energy level flag, steps 1405 to 1408 are repeated until the radiation source submodule (31) has not received any new energy level flag from the controller (50).

[0085] Figure 9 The diagram illustrates the method for passing through Figure 7 The flowchart of the sub-step of step 1600 of the method, in which the processor (61) determines the material and type of substance of the cargo, is shown. The processor (61) performs signal conditioning as in step 1601. Signal conditioning is performed using multi-energy transmittance values ​​of radiation that have not passed through any object and are directly captured by the data acquisition submodule (32).

[0086] The processor (61) suppresses the effects of hardware layout and dose fluctuations by adjusting and scaling the multi-energy transmittance values ​​based on the radiation values ​​that do not pass through any object, through the calibration scan lines. The multi-energy transmittance values ​​are then normalized by dividing the intensity value of each detected pixel by the highest possible intensity value. In this regard, the processor (61) further denoises the multi-energy transmittance values ​​by grouping adjacent pixels using a preset window size. Based on this, a grayscale representation image of the scanned object is generated.

[0087] Then, as in step 1610, the processor (61) selects a pair of energy levels as the first-stage filter for material classification. This pair of energy levels is selected from any possible combination of multi-energy level radiation. One of the energy levels is designated as a high energy level, while the other is designated as a low energy level.

[0088] As in step 1620, the processor (61) then calculates the normalized high-energy-level transmittance for each pixel of the image generated at the high-energy level by dividing the intensity value of the pixel for the high-energy-level image by the highest possible intensity value. As in step 1630, the processor (61) also calculates the normalized low-energy transmittance for each pixel of the image generated at the low-energy level. The normalized low-energy transmittance is calculated by dividing the intensity value of the pixel for the low-energy-level image by the highest possible intensity value.

[0089] Regarding this, as in step 1640, the processor (61) calculates a function value for each pixel, where the function value is the ratio of high-energy-level transmittance to low-energy-level transmittance. The function value is calculated based on the following equation:

[0090]

[0091] The function values ​​of all pixels are plotted on pre-generated material classification curves. The material classification curve for each material is generated by plotting the function values ​​of the sample material on a graph, where the y-axis represents the function value and the x-axis represents the normalized high-energy-level transmittance. A logarithmic curve fitting method is used to fit the function values ​​of the sample material to generate a trend line for the material.

[0092] As in step 1650, the processor (61) classifies each pixel into its corresponding material type based on the proximity of the function value plotted on the pre-generated material classification curve to the material's trend line. Examples of material types are organics, intermediate mixtures of organics and inorganics, inorganics, and heavy metals. In the analyzed image, each type of material is represented by a different color. If there are overlapping areas of material curves during classification, one material is prioritized over others based on the distance between the function value and the material's trend line.

[0093] Subsequently, as in step 1660, the processor (61) selects two additional pairs of energy levels as a second filter for material verification. The additional two pairs of energy levels are selected from any possible combination of multi-energy level radiation. One pair of energy levels is referred to as the first energy level pair, and the other pair is referred to as the second energy level pair.

[0094] As in step 1670, the processor (61) calculates the function value of the first and second energy level pairs for each pixel. The steps for calculating the function value of the first and second energy levels are similar to those in steps 1630 and 1640. For each energy level pair, the normalized high-energy-level transmittance and normalized low-energy-level transmittance for each pixel of the image generated for the high-energy-level and low-energy-levels are calculated. In this regard, the processor (61) calculates the function value of the first and second energy level pairs for each pixel based on the above equation (1).

[0095] The function values ​​of the first and second energy level pairs for each pixel were plotted on multiple pre-generated material groups. Each material group was generated by plotting the function values ​​of the first and second energy level pairs of the sample material on the graph, so that the y-axis was represented by the function values ​​of the first energy level pair and the x-axis by the function values ​​of the second energy level pair. The center of the material group was determined using the K-means clustering algorithm.

[0096] As in step 1680, the processor (61) then further classifies each pixel of the object into its corresponding substance group. Pixels are classified based on the proximity of the function values ​​of the first and second energy level pairs to the center of each substance group. After a pixel is classified into its substance group, the processor (61) highlights the region of the same substance in the analyzed image by defining the perimeter of the object for the substance within the pseudo-color image.

[0097] Although the system described above includes a radioactivity detection module (10), a weight sensing module (20), a radiation module (30), a controller (50), a server (60), and a display module (90), it will be apparent to those skilled in the art that the system and method can be modified and adapted to primarily include the radiation module (30) and the controller (50). Such modifications and adaptations can still be used to perform the inspection of cargo using multi-energy level radiation.

[0098] Although embodiments of the invention have been described and illustrated, these embodiments are not intended to illustrate and describe all possible forms of the invention. Rather, the language used in this specification is descriptive rather than restrictive, and various changes may be made without departing from the scope of the invention.

Claims

1. A system (100) for inspecting cargo using multi-energy level radiation, comprising: a) A radiation module (30) having a radiation source submodule (31) and a data acquisition submodule (32), wherein the radiation source submodule (31) is configured to generate radiation emitted to the cargo, and wherein the data acquisition submodule (32) is configured to capture the radiation emitted from the radiation source submodule (31), and b) A controller (50) configured to trigger the radiation source submodule (31) to start and stop generating the radiation and to control the energy level and pulse frequency of the radiation generated by the radiation source submodule (31), wherein the controller (50) is connected to the radiation module (30). Its features are: c) The radiation source submodule (31) is also configured to successively generate radiation pulses at at least three different energy levels; d) The data acquisition submodule (32) is further configured to capture the radiation at at least three different energy levels, and convert the captured radiation into an image for each energy level, wherein each pixel value in each image represents the transmittance of the captured radiation at at least three different energy levels; e) The radiation module (30) further includes a data storage (33) connected to the radiation source submodule (31), wherein the data storage (33) is configured to store setting data and a lookup table for generating radiation at at least three different energy levels by the radiation source submodule (31), wherein the setting data includes the number of energy levels of the radiation, the energy level value of the radiation, the injection current setting, and the pulse frequency of the radiation, and wherein the lookup table contains extended phase timing values; f) The system (100) further includes a server (60) connected to the radiation module (30), wherein the server (60) has a processor (61) configured to determine whether the cargo contains any contraband by analyzing the images at each energy level; and g) The radiation module is also configured to evaluate the instantaneous state of the equilibrium orbit and morphology of the magnetic field of the radiator (40) of the radiation source submodule.

2. The system (100) as claimed in claim 1, wherein, The at least three energy levels of the radiation are in the range of 2.0 MeV to 9.0 MeV, and the pulse frequency is in the range of 300 Hz to 500 Hz.

3. The system (100) as claimed in claim 1, wherein, The system (100) further includes a radioactivity detection module (10) configured to determine whether the cargo contains any radioactive material, and wherein the radioactivity detection module (10) is connected to the server (60) to notify the server (60) whenever radioactive material is detected in the cargo.

4. The system (100) as claimed in claim 1, wherein, The system (100) further includes a weight sensing module (20) configured to determine the presence of a vehicle carrying the freight based on the weight and number of axles of the freight, and wherein the weight sensing module (20) is connected to the server (60) and the controller (50) to trigger the radiation module (30) to start or stop scanning the freight.

5. The system (100) as claimed in claim 4, wherein, The weight sensing module (20) includes at least a pair of strip sensors placed on the surface of the road path to weigh the vehicle carrying the freight.

6. The system (100) as claimed in claim 4, wherein, The weight sensing module (20) includes a scale (20m) configured to detect the presence of the freight and measure the weight of the freight.

7. The system (100) as claimed in claim 1, wherein, The system (100) also includes a display module (90) connected to the server (60), wherein the display module (90) is configured to display the analyzed image, data from the radioactivity detection module (10), and weight information from the weight sensing module (20).

8. The system (100) as described in claim 1 further includes a radioactivity detection module (10) and a weight sensing module (20), wherein, The radioactivity detection module (10), the weight sensing module (20), and the radiation module (30) are installed along the road path traveled by the vehicle carrying the freight.

9. A method for inspecting cargo using multi-energy level radiation, comprising the following steps: a) Continuously generate radiation at at least three energy levels; b) Capture the radiation and convert the captured radiation into multiple images or each energy level; c) Determining the type of material in the freight based on the plurality of images, wherein determining the type of material in the freight includes: i) Perform signal conditioning; ii) Select a pair of energy levels as the first-level filter for material classification, wherein one of the energy levels is represented as a high energy level and the other energy level is represented as a low energy level; iii) Calculate the normalized high-energy-level transmittance for each pixel of the image produced for the high-energy level; iv) Calculate the normalized low-energy-level transmittance for each pixel of the image produced for the low-energy level; v) Calculate a function value for each pixel, where the function value is the ratio of the high-energy-level transmittance to the low-energy-level transmittance; and vi) Classify each pixel into a corresponding material type based on the proximity of the function value on multiple pre-generated material classification curves to the material's trend line, wherein each pre-generated material classification curve corresponds to a material type; and d) Determine the type of material in the freight shipment.

10. The method of claim 9, wherein, The steps of subsequently generating said radiation at at least three energy levels include: a) Obtain setting data for the energy level of the radiation, wherein the setting data includes the number of energy levels of the radiation, the pulse frequency of the radiation, the injection current to the acceleration chamber (41) and the magnetic field value supplied to the antimagnetic circuit (45) and the extended winding (46), and the voltage value to be supplied to the high-voltage injection unit (42). b) The radiation source submodule obtains the extended phase timing value corresponding to each energy level from the data memory (33); c) Pre-accelerated electrons are injected into the acceleration chamber (41) by the high-voltage injection unit (42); d) Determine the value of the energy level to be generated based on the energy level signal; e) Supplying current pulses to the contraction winding (47) to generate radiation with a dose rate determined by the setting data; and f) Supply current pulses to the extended winding (46) to generate radiation according to the energy level indicated in the energy level signal.

11. The method of claim 10, wherein, The subsequent generation of radiation at at least three energy levels also includes the following steps: a) Determine whether the radiator (40) has reached an equilibrium state for emitting the highest radiation dose rate by evaluating the instantaneous state of the equilibrium orbit and morphology of the magnetic field of the radiator (40) of the radiation source submodule; and If the radiator does not reach the equilibrium state, another combination of injected current value and current pulse value for the contraction winding (47) is searched and stored.

12. The method of claim 9, wherein, The steps of capturing the radiation and converting the captured radiation into multiple images or per energy level include: a) Receive energy level signals from the radiation source submodule (31) and the controller (50), wherein the first energy level signal includes a low voltage and the subsequent energy level signal includes a high voltage; b) Capture radiation with specific energy levels from the radiation source submodule (31) and convert the captured radiation pulses into a scan line for each energy level of the image; and c) Compile multiple scan lines with the same energy level to form multiple images.

13. The method of claim 9, wherein, Execution signal conditioning includes: a) By adjusting and scaling the values ​​of multi-energy transmittance based on radiation values ​​that do not pass through any object, the effects of hardware layout and dose fluctuations can be suppressed by calibrating multiple scan lines; b) Normalize the multi-energy level transmittance values ​​by dividing the detected intensity value of each pixel by the highest possible intensity value; and c) The multi-energy level transmittance values ​​are denoised by grouping adjacent pixels using a preset window size.

14. The method of claim 9, wherein, The normalized high-energy-level transmittance for each pixel of the image generated for the high-energy level is calculated by dividing the intensity value of that pixel of the image generated for the high-energy level by the highest possible intensity value.

15. The method of claim 9, wherein, The normalized low-energy-level transmittance for each pixel of the image generated for the low-energy level is calculated by dividing the intensity value of that pixel of the image generated for the low-energy level by the highest possible intensity value.

16. The method of claim 9, wherein, Calculate the function value for each pixel. f(x, y) It is based on the following equation: 。 17. The method of claim 9, wherein, Determining the type of substance in the freight shipment includes the following steps: a) Select two pairs of energy level combinations as the second-level filter for material verification, where one pair of energy levels is called the first energy level pair and the other pair of energy levels is called the second energy level pair; b) Calculate the function value for the first and second energy level pairs for each pixel; c) Plotting the function values ​​of the first and second energy level pairs for each pixel on multiple pre-generated material groups, wherein each material group is generated by plotting the function values ​​of the first and second energy level pairs of the sample material in the graph; and d) Each pixel is classified into the corresponding material group based on the proximity of the function values ​​of the first and second energy level pairs to the center of each material group.

18. The method of claim 17, wherein, The steps for calculating the function values ​​for the first and second energy level pairs for each pixel include: a) Calculate the normalized high-energy-level transmittance for each pixel of the image produced at the high-energy level for the first and second energy level pairs; b) Calculate the normalized low-energy-level transmittance for each pixel of the image produced at the low-energy level, for both the first and second energy level pairs; and c) Calculate the function value for each pixel for the first and second energy level pairs, wherein the function value for each pixel... f(x,y) It is calculated based on the following equation: 。 19. The method of claim 9, wherein, The steps preceding the generation of radiation at at least three energy levels include: a) The presence of the cargo is detected by the weight sensing module (20) based on tire detection and the weight of the cargo; b) Calculate the total weight of the freight and the number of axles of the freight using the weight sensing module (20) based on tire detection; c) Determine whether the cargo shipment includes any radioactive material using the radioactivity detection module (10); and d) If the shipment includes radioactive material, a notification is sent to the output module (90).

Images