CN115684225A - Handheld back scattering imager and imaging method thereof - Google Patents

Abstract

The invention provides a hand-held backscatter imager and an imaging method thereof. The hand-held backscatter imager includes: a pencil beam X-ray source, a detector, a static flat panel detector, a display screen and a data acquisition control circuit; the invention has It is small in size, light in weight, portable and can be close to the measured object, and can scan and image the measured object from multiple angles in all directions; the trumpet-shaped shielding structure of the present invention and the nested connection of the fan-shaped pre-collimator can effectively shield X Scattering of rays; the photoelectric converter of the SiPM in the detector of the present invention has the characteristics of small volume and high gain, which is conducive to the miniaturization of the backscatter imager, and can also control the cost accordingly; the detector of the present invention adopts The light guide can greatly improve the collection efficiency of the photoelectric conversion device, thereby improving the imaging resolution of the handheld backscatter imager.

Description

Hand-held backscatter imager and its imaging method

technical field

The invention relates to the technical field of radiation imaging inspection, in particular to a hand-held backscatter imager and an imaging method thereof.

Background technique

Backscatter imaging technology is an imaging technology that detects the intensity of X-ray scattering by different substances to obtain a material image within a certain depth of the surface of the detected target. Backscatter imaging technology has the characteristics of low radiation dose, good safety, sensitivity to light materials, and the radiation source and detector can be arranged on the same side of the measured target. It is not only suitable for imaging inspection of explosives, drugs and other organic substances, It is also suitable for imaging detection of large objects such as large objects and vehicle interlayers. Therefore, backscatter vehicle-mounted and fixed imaging devices are widely equipped by civil aviation, customs, public security and frontier defense.

With the advancement of electric vacuum and detector technology, the miniaturized radiation source and detector technology are changing with each passing day, and the handheld backscatter imager becomes possible. The hand-held backscatter imager is small in size, light in weight, portable and close to the target, and can scan and image the inspection target from multiple angles, which greatly facilitates security personnel and public security border guards, and is favored.

Compared with the traditional X-ray transmission imaging technology, X-ray backscatter imaging technology has the characteristics that the radiation source and the detector are arranged on the same side of the detected object, and the backscatter signal can highlight the organic matter, which is very suitable for explosives, Imaging inspection of organic substances such as drugs and large objects. With the advancement of ray source technology, miniaturized and high-energy (120-160keV) ray tubes are introduced, which makes it possible to make the backscatter imager portable and hand-held. The handheld backscatter imager has the advantages of small size, light weight, portability and in-situ inspection close to the target.

In view of the above, it is necessary to provide a hand-held backscatter imager and its imaging method, which are small in size, light in weight, portable and can be close to the measured object, and can scan and image the measured object from multiple angles in all directions, and In terms of production cost, it can also meet the demand of high cost performance.

Contents of the invention

In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a hand-held backscatter imager and its imaging method, which can achieve small size, light weight, portability, closeness to the measured object, and multi-angle omnidirectional Scanning and imaging the target object to be measured can also meet the cost-effective requirements in terms of production cost.

In order to achieve the above purpose and other related purposes, the present invention provides a handheld backscatter imager. The handheld backscatter imager includes:

Pencil beam X-ray source, detector, static flat panel detector, display screen and data acquisition control circuit;

The pencil beam X-ray source includes an X-ray generator, an X-ray fan collimator and a chopping mechanism;

The X-ray generator is used to emit X-ray beams;

The X-ray fan-shaped collimator is located on the front side of the X-ray generator, and includes a fan-shaped pre-collimator and a bell-mouth shielding structure, and the bell-mouth-shaped shielding structure is nested and connected to the fan-shaped pre-collimator, The fan-shaped pre-collimator is provided with a collimator slit for collimating the X-ray beam emitted by the X-ray generator into a narrow beam, and the horn-mouth shielding structure is used for shielding the scattered X-ray beam. beam of rays;

The chopper mechanism is located between the detector and the bell mouth shielding structure, and includes a chopper flywheel and a driver, and the chopper flywheel is provided with chopping slits at equal angles; the driver is used to drive the chopping slits intersect alternately with the collimator slits, so that the X-ray beam emitted by the X-ray generator forms periodically reciprocating pencil beam X-rays;

The detector is located at the forefront of the hand-held backscatter imager, including a photoelectric converter of SiPM and an optical system of a light guide, and the detector is used to receive the scattering signal data of the surface of the measured target;

The static flat panel detector is a wireless detector, used as a backscatter expansion detector of the handheld backscatter imager, used to improve the signal-to-noise ratio of the backscatter image, or as a transmission of the handheld backscatter imager a detector for simultaneously acquiring a backscatter image and a transmission image during scanning;

The display screen is located directly above the handheld backscatter imager, and is used to provide a human-computer interaction interface and receive and display a stereoscopic image of the surface of the measured object;

The data acquisition control circuit is used to control and execute the data communication, data preprocessing and image reconstruction of the handheld backscatter imager.

Optionally, the hand-held backscatter imager is also provided with auxiliary peripherals, the auxiliary peripherals include a gyroscope, a SLAM camera, and a laser marker light; Inside the scatter imager, it is used to obtain the trajectory information of the scanning plane coordinates, and combined with the shooting guidance presented on the display screen, prompts the operator to correct the backscatter scanning attitude; the SLAM camera is located at the front end of the detector and is used for visible light Evidence collection, video recording of the shooting process, and backscatter image correction through the video image; the two laser position marker lights are arranged in parallel, located at the front end of the detector, and are used to assist the operator to grasp the backscatter imaging scanning process in real time The imaging area that can be covered by the middle ray, and the operator's holding angle of the handheld backscatter imager can be corrected in time by observing the angles of the two columns of laser beams emitted by the two in-line laser position lights.

Optionally, the handheld backscatter imager is also provided with a transmission module to facilitate uploading and interaction of images.

Optionally, the collimator slit collimates the outgoing X-ray beam into a fan-shaped narrow beam with an angle range of 60°*1.5°, and the collimator slit width ranges from 0.1 mm to 0.5 mm; The bell-mouth-shaped shielding structure includes a first slit close to the fan-shaped pre-collimator and a second slit away from the fan-shaped pre-collimator, and the angle range of the bell-mouth-shaped shielding structure is 61° *2°～65°*2°, the width of the first slit is greater than the width of the collimator slit; The slits are on the same axis of symmetry.

Optionally, the drive mode for the driver to drive the chopper flywheel is direct drive by a motor or indirect drive synchronously driven by gears; the width of the chopper slit on the chopper flywheel ranges from 0.15 mm to 0.65 mm.

Optionally, a shielding mechanism is also provided between the chopper flywheel and the detector, located above the chopper flywheel, to prevent the X-ray beam from exciting the chopper flywheel to generate characteristic X-rays, causing the Detector signal response and radiation leakage rate exceeded the standard.

Optionally, the detector also includes: a front cover plate of the detector, a detector box, a scintillator, and a readout amplification circuit matched with the photoelectric converter; the scintillator is located at the front end of the detector, The photoelectric sensor and the supporting readout amplification circuit are located behind the scintillator, and the detector front cover and the detector box amplify the scintillator, the photoelectric sensor and the supporting readout The circuit is wrapped in it; the scintillator is used to absorb X-rays and convert the absorbed X-ray energy into visible light signals, and the scintillator is a crystal scintillator or a thin film scintillator; the matching readout amplifier circuit is used The voltage signal output by the photoelectric converter is shaped, filtered and amplified.

Optionally, the detector further includes: a reflective layer, which is used to reduce the absorption of scintillator fluorescence by materials inside the detector, so as to improve the collection effect of the photoelectric sensor on the light signal of the scintillator. The layer is located in the inner cavity of the detection box and is evenly arranged, and the material is one of MgO, Al ₂ O ₃ , Tyvek, aluminum foil and PTFE film.

The present invention also provides an imaging method of a hand-held backscatter imager, the imaging method comprising:

S1: start the hand-held backscatter imager, whether the self-check of the hand-held backscatter imager is normal, if not, the cause of the fault and the guidance plan to solve the fault will be displayed on the display screen, and enter the self-test completion interface according to the guidance, If so, directly enter the self-inspection completion interface, and set the scanning parameters on the self-inspection completion interface;

S2: The handheld backscatter imager includes three modes when scanning the target; one is the backscatter mode, aiming the handheld backscatter imager at the target and starting the handheld backscatter imager The scan button is used to shoot the pencil beam X-rays on the measured object for scanning; the second is the backscatter enhancement mode, where the static flat panel detector and the hand-held backscatter imager are placed on the same side without overlapping and connected to the The static flat panel detector and the handheld backscatter imager start the scanning button of the handheld backscatter imager to start the backscatter imaging scan, and the detector and the static flat panel detector simultaneously receive information from the measured target the scattering signal of the object; the third is the backscattering+transmission mode, the static flat panel detector is placed on the rear side of the measured object, and is in the whole scanning field of view of the handheld backscattering imager, connected to the Static flat panel detector and the handheld backscatter imager, start the scan button of the handheld backscatter imager to start backscatter and transmission imaging scanning;

S3: Perform data preprocessing on the scattered signals received by scanning, and perform image rearrangement, and finally display the image information of the measured object on the display screen.

Optionally, the imaging method of the hand-held backscatter imager also includes image correction with auxiliary peripherals of a gyroscope, a SLAM camera and a laser marker light: 2 said laser markers arranged in parallel The parallel laser beam emitted by the profile lamp and the pencil beam X-rays hit the target at the same time, and the width of the two parallel columns of the laser beams shows the width range that the pencil beam X-rays can cover. The parallelism of the laser beam shows whether the plane of the detector is parallel to the plane of the measured object, which is used to instruct the operator to adjust the scanning posture and imaging scanning range; the gyroscope can display the current shooting posture or the measured object The plane coordinate information of the target object guides the operator to scan in a straight line to avoid image bending; the SLAM camera actively takes pictures of the measured target object, and also takes pictures during the scanning process to obtain the three-dimensional coordinate information of the measured target object, The acquired three-dimensional coordinate information of the measured object can correct the image distortion caused by the scanning path through the difference value and the coordinate translation.

As mentioned above, the hand-held backscatter imager and its imaging method of the present invention have the following beneficial effects: the present invention is small in size, light in weight, portable and can be close to the measured object, and can monitor the measured object from multiple angles and all directions. The target object is scanned and imaged; the horn-mouth-shaped shielding structure of the present invention is nestedly connected with the fan-shaped pre-collimator to effectively shield the scattering of X-rays; the photoelectric converter of the SiPM in the detector of the present invention has a small size and high gain feature, which is beneficial to the miniaturization of the backscatter imager, and can also control the cost accordingly; the detector of the present invention uses a light guide, which can greatly improve the collection efficiency of the photoelectric conversion device, thereby improving the performance of the hand-held backscatter imager. Imaging resolution.

Description of drawings

FIG. 1 is a schematic diagram of the overall structure of the handheld backscatter imager of the present invention.

Fig. 2 is a schematic front view of the detector of the present invention.

FIG. 3 is a schematic cross-sectional view of FIG. 2 .

Fig. 4 is a schematic structural diagram of the pencil beam X-ray source of the present invention.

Fig. 5 is a schematic flow chart of the imaging method of the handheld backscatter imager of the present invention.

Component designation description

10 Pencil beam X-ray source

11 X-ray generator

121 sector pre-collimator

122 bell mouth shielding structure

131 chopper flywheel

132 Chopping Slit

133 shielding mechanism

20 detectors

21 Detector front cover

22 detector box

23 scintillators

24 photoelectric converter

25 matching sense amplifier circuit

26 reflective layer

27 Optical system

30 Data Acquisition Control Circuit

40 Display

50 battery pack

60 SLAM cameras

70 word laser marker lights

80 complete case

Detailed ways

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention.

For example, when describing the embodiments of the present invention in detail, for the convenience of explanation, the cross-sectional view showing the device structure will not be partially enlarged according to the general scale, and the schematic diagram is only an example, which should not limit the protection scope of the present invention.

For the convenience of description, spatial relation words such as "below", "below", "below", "below", "above", "on" etc. may be used herein to describe a structure or structure shown in the drawings. The relationship of a feature to other structures or features. It will be understood that these spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. In addition, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. As used herein, "between" means that both endpoints are inclusive.

In the context of this application, structures described as having a first feature "on top of" a second feature may include embodiments where the first and second features are formed in direct contact, as well as additional features formed between the first and second features. Embodiments between the second feature such that the first and second features may not be in direct contact.

See Figures 1 through 5. It should be noted that the diagrams provided in this embodiment are only schematically illustrating the basic idea of the present invention, so that only the components related to the present invention are shown in the diagrams rather than the number, shape and Dimensional drawing, the type, quantity and proportion of each component can be changed arbitrarily during actual implementation, and the component layout type may also be more complicated.

Embodiment one

As shown in Figures 1 to 4, this embodiment provides a handheld backscatter imager, which includes:

Pencil beam X-ray source 10, detector 20, static flat panel detector, display screen 40 and data acquisition control circuit 30;

The pencil beam X-ray source includes an X-ray generator 11, an X-ray fan collimator and a chopping mechanism;

The X-ray generator 11 is used to emit X-ray beams;

As shown in Figure 4, the X-ray fan-shaped collimator is located at the front side of the X-ray generator 11, and includes a fan-shaped pre-collimator 121 and a bell-mouth shielding structure 122, and the bell-mouth-shaped shielding structure 122 is connected to the The fan-shaped pre-collimator 121 is nested and connected, and the fan-shaped pre-collimator 121 is provided with a collimator slit for collimating the X-ray beam emitted by the X-ray generator 11 into a narrow beam , the horn mouth shielding structure 122 is used to shield the scattered X-ray beam;

As shown in Figures 1 and 4, the chopper mechanism is located between the detector 20 and the bell mouth shielding structure 122, including a chopper flywheel 131 and a driver, and the chopper flywheel 131 is provided with The chopping slit 132; the driver is used to drive the chopping slit 132 to alternately intersect with the collimator slit, so that the X-ray beam emitted by the X-ray generator 11 forms a periodically reciprocating pencil-shaped beam X-rays;

As shown in Figure 3, the detector 20 is located at the forefront of the hand-held backscatter imager, including a photoelectric converter 24 of SiPM, and the detector 20 is used to receive the scattering signal data of the surface of the measured object ;

The static flat panel detector is a wireless detector, which can be used as a backscatter expansion detector of the handheld backscatter imager to improve the signal-to-noise ratio of the backscatter image, and can also be used as the handheld backscatter imager A transmission detector for simultaneous acquisition of backscattered images and transmission images during scanning;

The display screen 40 is located directly above the handheld backscatter imager, and is used to provide a human-computer interaction interface and receive and display a stereoscopic image of the surface of the measured object;

The data acquisition control circuit 30 is located below the display screen 40 and is used to control and execute the data communication, data preprocessing and image reconstruction of the handheld backscatter imager.

The working principle of the handheld backscatter imager is as follows: the X-ray generator 11 emits a large-angle conical X-ray beam, and the fan-shaped pre-collimator 121 collimates the large-angle conical X-ray beam into a predetermined shape. A sheet-shaped fan-shaped narrow beam with an angle is set, and the X-ray beam of the narrow beam passes through the horn mouth shielding structure 122 to shield the scattered X-rays from entering the chopper mechanism, and the chopper on the rotating chopper flywheel 131 The slit 132 forms a narrow beam of X-rays into periodically reciprocating pencil beam X-rays; the periodically moving pencil beam X-rays combine with the operator of the handheld backscatter imager in a direction orthogonal to the movement of the pencil beam X-rays The implementation of the uniform movement to complete the imaging detection of the detected target, specifically the pencil beam X-rays hitting the measured target and the extranuclear electrons inside the measured target produce back Compton scattering Effect, so that the direction of movement of photons is deflected by more than 90° from the original incident direction, and the deflected X-rays receive scattered signal data through the detector 20 to generate optical signals, and convert the optical signals into current signals, and Zooming in; performing corresponding data preprocessing and image reconstruction to finally present the image of the measured object on the display screen 40 . At the same time, with the help of a static flat panel detector, it can be placed in different positions to expand the backscatter imaging range or obtain backscatter images and transmission images.

It should be noted here that, for the sake of X-ray scattering shielding, the fan-shaped pre-collimator 121 and the bell mouth shielding structure 122 need to use high-density materials. The material of the device 121 is preferably metal tungsten, and the material of the bell mouth shielding structure 122 is preferably metal copper.

The photoelectric converter of the detector 20 is used to convert optical signals into electrical signals. In the prior art, a photomultiplier tube (Photomultiplier Tube, PMT) is mostly used as the photoelectric converter of the detector. poor, which limits the further miniaturization of the hand-held backscatter imager, and it is difficult to meet the application requirements of harsh detection environments. In this embodiment, silicon photomultiplier (Silicon Photomultiplier, SiPM) is used as the photoelectric converter of the detector. SiPM has a volume Small size and high gain, and the SiPMs in this embodiment are arranged in the form of an area array, which further reduces the cost.

The static flat panel detector expands the handheld backscatter imager through its placement position, and the static flat panel detector and the handheld backscatter imager are placed on the same side without overlapping, which can be used as the handheld backscatter imager The backscattering extended detector of the backscattering imager is used to improve the signal-to-noise ratio of the backscattering image; the static flat panel detector is placed on the back side of the measured target and is in the full field of view of the handheld backscattering imager Within the range, it can be used as the transmission detector of the handheld backscatter imager, which is used to simultaneously acquire backscattered images and transmission images during the scanning process; at this time, the static flat panel detector can only receive the measured target The scattered signal of the object, but it cannot be imaged. The signal needs to be transmitted to the handheld backscatter imager for signal superposition with the signal received by the detector 20 , and then the image is displayed on the display 40 .

In addition, as shown in Figure 1, the handheld backscatter imager also includes a battery pack 50 and a complete machine housing 80, the battery pack is used to provide the energy required for the operation of the entire device, and lithium is preferably used in this embodiment. As for the battery pack, the whole machine casing 80 is used to assemble various devices of the whole device, and the whole machine casing 80 is made of ABS or other plastic materials to meet the requirements of light weight and high strength of the whole device. The X-ray sector collimator 11 is a miniature bipolar X-ray sector collimator, which is suitable for small hand-held backscatter imagers. The chopper mechanism also includes a fixing bracket for fixedly connecting other components of the chopper mechanism.

As shown in Figures 1 to 2, as an example, the handheld backscatter imager is also provided with auxiliary peripherals, and the auxiliary peripherals include gyroscopes, simultaneous positioning and map building (Simultaneous Localization And Mapping, SLAM ) camera 60, supplementary light and a word laser position marker light 70; the gyroscope is located inside the hand-held backscatter imager, and is used to obtain the track information of the scanning plane coordinates, and combined with the display screen 40 presented The shooting guide prompts the operator to correct the backscatter scanning posture; as shown in Figure 2, the SLAM camera 60 is located at the front end of the detector 20, which can be used for visible light evidence collection on the one hand, and video recording of the shooting process on the other hand. The backscattered image is corrected for the video image; the supplementary light is located on the side of the SLAM camera 60, and is used to supplement the light for the shooting of the SLAM camera 60 under weak light or dark detection conditions; the one-character laser outline There are two lights 70 arranged in parallel, which are located at the front end of the detector 20 and respectively located on both sides of the SLAM camera 60, and are used to assist the operator in real-time grasping the imaging area that the rays can cover during the backscatter imaging scanning process, and can pass through Observing the angles of the two rows of laser beams emitted by the two straight-line laser position marker lights 70 corrects the operator's holding angle of the handheld backscatter imager in time.

As an example, the handheld backscatter imager is also provided with a transmission module, such as WiFi and Bluetooth, to facilitate uploading and interaction of images.

When the static flat panel detector is used to extend the handheld backscatter imager, the detector 20 can be connected via Bluetooth and WiFi, and the received signals can be transmitted.

As shown in Figure 4, as an example, the collimator slit collimates the outgoing X-ray beam into a narrow beam with an angle range of 60°*1.5°, and the collimator slit width range is 0.1mm ~0.5mm; the bell-mouth-shaped shielding structure includes a first slit close to the fan-shaped pre-collimator and a second slit away from the fan-shaped pre-collimator, and the bell-mouth-shaped shielding structure 122 The angle range is 61°*2°～65°*2°, the width of the first slit is larger than the width of the collimator slit; when nested installation, the collimator slit and the first The slit and the second slit are on the same axis of symmetry.

It should be noted here that the narrow beam is in the shape of a sheet fan, and the X-ray beams are all thick line beams. In order to shield the scattering of the X-ray beam and not block the narrow beam, the first slit is set The width of the collimator slit is greater than the width of the collimator slit, and when it is nested, the collimator slit is on the same axis of symmetry as the first slit and the second slit, so that the narrow beam Can shoot completely.

As shown in Figure 4, the drive mode of the driver to drive the rotation of the chopper flywheel 131 is the direct drive of the motor or the indirect drive driven synchronously by the gears; the width range of the chopping slit 132 on the chopper flywheel 131 is 0.15mm ~0.65mm.

The type and driving mode of the driver can be selected according to actual needs, as long as the driver can drive the chopper flywheel 131 to rotate; The X-ray fan-shaped collimator cooperates to form the X-ray beam emitted by the X-ray generator 11 into periodically reciprocating pencil beam X-rays, and the chopping slit 132 also has a corresponding shape, which is trapezoidal or Circular, set at equal angles on the chopper flywheel 131; when the chopper slit 132 is trapezoidal, it is in the shape of a long trapezoid, the minimum length of the upper base is 0.15mm, and the maximum length of the lower base is 0.65 mm; when the chopping slit 132 is circular, the minimum diameter of the circle is 0.15 mm, and the maximum is 0.65 mm.

As an example, a shielding mechanism 133 is also provided between the chopper flywheel 131 and the detector 20, located above the chopper flywheel 131, for preventing the X-ray beam from exciting the chopper flywheel 131 to generate characteristic X-rays. , causing the signal response and radiation leakage rate of the detector 20 to exceed the standard.

As shown in Figures 2 to 3, as an example, the detector 20 also includes: a detector front cover 21, a detector box 22, a scintillator 23 and a readout amplifier circuit 25 matched with the photoelectric converter; The scintillator 23 is located at the forefront of the detector 20, the photoelectric sensor 24 and the associated readout amplifier circuit 25 are located behind the scintillator 23, the detector front cover 21 is connected to the detector The device box 22 wraps the scintillator 23, the photoelectric sensor 24 and the supporting readout amplifier circuit 25; the scintillator 23 is used to absorb X-rays and convert the absorbed X-ray energy into visible light signals. The scintillator 23 is a crystal scintillator or a thin film scintillator; the matching readout amplifier circuit 25 is used for shaping, filtering and amplifying the voltage signal output by the photoelectric converter 24 .

As shown in FIGS. 2 to 3 , as an example, the detector 20 further includes: a reflective layer 26 for reducing the absorption of the fluorescence of the scintillator 23 by the materials inside the detector 20 to improve the photoelectric sensor 24 to the The collection effect of the optical signal of the scintillator 23; the reflective layer 26 is located in the inner cavity of the detection box 22, and is evenly arranged, and the material is one of MgO, Al ₂ O ₃ , Tyvek, aluminum foil and PTFE film.

The optical system 27 in the detector 20 is a lens or a light guide coupled between the scintillator 23 and the photoelectric sensor 24. In this embodiment, a variable-diameter optical fiber is preferably used to connect the scintillator 23 and the photoelectric converter 24, the junction is bonded with optical glue, and the use of a total reflection variable-diameter light guide can greatly improve the collection efficiency of the photoelectric conversion device 24 for the fluorescence of the scintillator 23, thereby improving the Imaging resolution of a handheld backscatter imager.

In this embodiment, the detector 20 adopts a frame structure, the detector box 22 includes a frame and a back cover, the outer frame is made of ABS or other plastic materials, and the back cover is made of opaque plastic The detector front cover 21 is a high-strength carbon plate, and the detector front cover 21 and the frame are sealed and installed in a light-proof manner with screws and sealing rubber pads. A layer of mirror-surfaced aluminum foil is spread evenly and evenly on the inner periphery of the detector box 22 as the reflective layer of the fluorescence of the scintillator 23 and the shielding layer of the weak photoelectric readout signal circuit. The scintillator 23 having the same size as the inner frame of the detector box 22 is arranged on the upper surface of the reflection layer 26 , and the material of the scintillator 23 may be CsI or CaWO ₄ . In this embodiment, it is preferable to use a variable-diameter optical fiber to connect the scintillator 23 and the photoelectric converter 24. The fluorescence collection efficiency of the scintillator 23 improves the imaging resolution of the handheld backscatter imager.

Embodiment two

This embodiment provides a specific embodiment of a handheld backscatter imager, the handheld backscatter imager includes:

Pencil beam X-ray source 10, detector 20, wireless static flat panel detector, display screen 40, data acquisition control circuit 30, lithium battery pack, RGBD camera, one-character laser position marker light 70 and machine casing 80.

The pencil beam X-ray source 10 includes a miniature bipolar X-ray generator, an X-ray fan-shaped collimator and a chopping mechanism, and the X-ray fan-shaped collimator includes a bell mouth shielding structure 122 nested and connected and a fan-shaped front Set the collimator 121, the material of the fan-shaped pre-collimator 121 is metal tungsten, the material of the bell mouth shielding structure 122 is metal copper, and the fan-shaped pre-collimator 121 is provided with a collimator slit , used to collimate the cone-shaped X-ray beam emitted by the X-ray generator 11 into a fan-shaped narrow beam of 60°*1.5°, wherein the slit width of the collimator slit is 0.8 mm, located at the The bell mouth shielding structure 122 of the fan-shaped pre-collimator 121 is used to reduce the leakage rate of the radiation source when it is working. The front end of the bell mouth shielding structure 122 is the chopping mechanism, and the bell mouth shielding structure 122 is close to The angle of the first slit of the fan-shaped pre-collimator 121 is 61°*2°, and the angle close to the chopper mechanism is 65°*2°, wherein the width of the first slit is larger than the Collimator slit width. Described chopping mechanism comprises chopping flywheel 131, DC motor and fixed support, and the material of described chopping flywheel 131 is metal tungsten, and described chopping flywheel 131 is provided with chopping slit 132 at equal angles, and the slit width is 0.4mm, the DC motor directly drives the chopper flywheel 131 to rotate, and the fixing bracket is used to fix the chopper flywheel 131 and the DC motor. The DC motor drives the chopping slit 132 to alternately intersect with the collimator slit, so that the X-ray beam emitted by the X-ray generator 11 forms a periodically reciprocating pencil beam X-ray.

The front end of the hand-held backscatter imager is a detector 20, that is, the front end of the chopper mechanism is the detector 20, and a shielding mechanism is also arranged between the chopper mechanism and the detector 20 133, used to prevent the fan-shaped X-rays from exciting the chopper flywheel 131 to generate characteristic X-rays, causing the signal response of the detector and the radiation leakage rate to exceed the standard. The detector 20 includes a detector front cover 21, a detector box 22, a scintillator 23, a SiPM and a supporting readout amplifier circuit 25, the scintillator 23 is located at the front end of the detector 20, and the SiPM And the matching readout amplifier circuit 25 is located behind the scintillator 23, the detector front cover 21 and the detector box 22 connect the scintillator 23, SiPM and the matching readout amplifier circuit 25 wrapped in it. The detector 20 adopts a frame structure. In order to meet the purpose of light weight and high strength, the outer frame of the detector box 22 and the outer shell 80 of the whole machine are made of ABS material. The rear of the detector box 22 The cover plate is made of opaque plastic material. The front cover plate 21 of the detector box is a high-strength carbon plate. The front cover plate 21 of the detector and the detector box 22 are sealed to avoid light by means of screws and sealing rubber pads. Install.

The detector front cover 21 is also provided with an X-ray beam outlet, which is used to emit the pencil beam X-rays and hit the measured object, and the detector 20 receives the scattering of the measured object. The X-rays generate optical signals through the scintillator 23, and convert the optical signals into electrical signals and amplify them through the SiPM and the associated readout amplifier circuit 25.

The detector 20 also includes a reflective layer of mirror-surface aluminum foil, and the mirror-surface aluminum foil is spread uniformly and evenly around the inner cavity of the detector box 22 to serve as a reflective layer for the fluorescence of the scintillator 23 and a shielding layer for the weak photoelectric readout signal circuit; The scintillator 23 is connected to the SiPM through a variable-diameter optical fiber, and the joint is bonded with optical glue. The use of the above-mentioned variable-diameter light guide of the total reflection type can greatly improve the collection efficiency of the fluorescence of the scintillator 23 by the SiPM. , so as to improve the imaging resolution of the handheld backscatter imager.

The RGBD camera and the one-word laser position marker light 70 are located on the front cover plate 21 of the detector, the RGB-D camera is used for visible light image or video shooting, and the captured image and video can be associated with the backscattered image. The vicinity of the RGB-D camera is also provided with an LED light for supplementary light for taking pictures; the said one-character laser position indicator light 70 is provided with 2, which are respectively arranged above the X-ray beam outlet, and the RGB-D camera The two sides are used to assist the operator to grasp in real time the imaging area that the rays can cover during the backscatter imaging scanning process, and to observe the angles of the two columns of laser beams emitted by the two in-line laser position lights 70 in real time. Correct the angle at which the operator holds the handheld backscatter imager. The handheld backscatter imager is also provided with a gyroscope inside, and the gyroscope can display the current shooting attitude or the plane coordinate information of the measured object, guide the operator to scan in a straight line, and avoid image bending.

In order to improve the imaging detection capability of the handheld backscatter imager, it is also necessary to support the wireless static flat panel detector through WIFI and Bluetooth. When the wireless static flat panel detector and the handheld backscatter imager are placed on the same side without overlapping, it can The backscatter imaging detection area is increased, and the signal-to-noise ratio of the image is improved, and the backscattering and transmission information of the measured target substance can be obtained at the same time when placed on the opposite side, so as to realize the detection of prohibited items with high Z and low atomic number and high electron density.

Embodiment Three

As shown in Figure 5, this embodiment provides its imaging method based on a handheld backscatter imager of Embodiment 1, and the imaging method of the handheld backscatter imager includes:

S1: start the hand-held backscatter imager, whether the self-check of the hand-held backscatter imager is normal, if not, the cause of the fault and the guidance plan to solve the fault will be displayed on the display screen, and enter the self-test completion interface according to the guidance, If so, directly enter the self-inspection completion interface, and set the scanning parameters on the self-inspection completion interface;

S2: The handheld backscatter imager includes three modes when scanning the target; one is the backscatter mode, aiming the handheld backscatter imager at the target and starting the handheld backscatter imager The scan button is used to shoot the pencil beam X-rays on the measured object for scanning; the second is the backscatter enhancement mode, where the static flat panel detector and the hand-held backscatter imager are placed on the same side without overlapping and connected to the The static flat panel detector and the handheld backscatter imager start the scanning button of the handheld backscatter imager to start the backscatter imaging scan, and the detector and the static flat panel detector simultaneously receive information from the measured target the scattering signal of the object; the third is the backscattering+transmission mode, the static flat panel detector is placed on the rear side of the measured object, and is in the whole scanning field of view of the handheld backscattering imager, connected to the Static flat panel detector and the handheld backscatter imager, start the scan button of the handheld backscatter imager to start backscatter and transmission imaging scanning;

S3: Preprocess the scattered signal received by scanning, perform image rearrangement, and finally display the image information of the measured object on the display screen

As an example, the imaging method of the hand-held backscatter imager also includes image correction with auxiliary peripherals of a gyroscope, a SLAM camera and a laser marker light: 2 parallel laser markers The parallel laser beam emitted by the lamp and the pencil beam X-rays hit the target at the same time, and the width of the two columns of parallel laser beams shows the width range that the pencil beam X-rays can cover. The two columns of the laser beams The parallelism of the beam shows whether the plane of the detector is parallel to the plane of the measured object, which is used to instruct the operator to adjust the scanning posture and imaging scanning range; the gyroscope can display the current shooting posture or the measured target The plane coordinate information of the object guides the operator to scan in a straight line to avoid image bending; the SLAM camera actively shoots and images the target object, and also takes pictures during the scanning process to obtain the three-dimensional coordinate information of the measured object. The image distortion caused by the scanning path can be corrected through the difference and coordinate translation of the three-dimensional coordinate information of the measured object.

In the backscatter mode, aim the handheld backscatter imager at the measured object, start the scan button of the handheld backscatter imager, and the two laser position lights emitted Parallel laser beams and pencil beam X-rays hit the measured object, and the width of the two parallel columns of laser beams shows the width range that the pencil beam X-rays can cover, and the parallel width of the two columns of laser beams The degree shows whether the plane of the detector 20 is parallel to the measured object, which is used to indicate the operator’s scanning attitude and imaging scanning range; during scanning, the gyroscope located inside the handheld backscatter imager can also Display the current shooting posture or the plane coordinate information of the measured object, guide the operator to scan in a straight line, and avoid image bending; in addition, during the imaging scanning process, the camera head of the SLAM camera located on the front cover plate 21 of the detector On the one hand, it will actively photograph and image the measured object, and on the other hand, it will also take pictures during the scanning process to obtain the three-dimensional coordinate information of the measured object; the obtained discrete scanning three-dimensional coordinate information can be obtained through difference and coordinate translation. Corrects image distortion caused by the scan path.

In the backscatter enhancement mode, place the static flat panel detector and the handheld backscatter imager on the same side without overlapping, connect the detector 20 via Bluetooth and WiFi, and start the handheld backscatter imager to scan button to start backscatter imaging scanning, the handheld detector and the static flat panel detector simultaneously receive the scattering signal from the measured object, and the detector 20 and the static flat panel are detected via Bluetooth and WiFi transmission The scattering signal received by the detector is superimposed, corrected, etc., and the image information of the measured object is displayed on the display screen. The grayscale and RGB color mode display of the display screen 40 can be adjusted and set by itself.

In the backscatter+transmission mode, the static flat panel detector is placed on the rear side of the object to be measured, and is within the full scanning field of view of the handheld backscatter imager, and connected to the static flat panel detector device and the handheld backscatter imager, start the scan button of the handheld backscatter imager to start the backscatter and transmission imaging scan, through the SLAM camera data correction, the backscatter image and the transmission image are presented on the display screen synchronously 40 on.

In summary, the present invention provides a handheld backscatter imager and an imaging method thereof. The handheld backscatter imager includes: a pencil beam X-ray source, a detector, a static flat panel detector, a display screen and data acquisition Control circuit; the pencil beam X-ray source includes an X-ray generator, an X-ray fan-shaped collimator and a chopping mechanism; the X-ray generator is used to emit X-ray beams; the X-ray fan-shaped collimator is located in the The front side of the X-ray generator includes a fan-shaped pre-collimator and a bell-mouth shielding structure, the bell-shaped shielding structure is nested and connected to the fan-shaped pre-collimator, and the fan-shaped pre-collimator is provided with The collimator slit is used to collimate the X-ray beam emitted by the X-ray generator into a narrow beam, and the horn mouth shielding structure is used to shield the scattered X-ray beam; the chopping mechanism is located at the A chopper flywheel and a driver are included between the detector and the horn-mouth shielding structure, and chopper slits are arranged at equal angles on the chopper flywheel; the driver is used to drive the chopper slit and the quasi- Straightener slits intersect alternately, so that the X-ray beam emitted by the X-ray generator forms a periodically reciprocating pencil beam X-ray; the detector is located at the forefront of the handheld backscatter imager, including a SiPM A photoelectric converter and an optical system that is a light guide, the detector is used to receive the scattering signal data of the surface of the measured object; the static flat panel detector is a wireless detector, which can be used as the backscattering of the handheld backscattering imager The extended detector is used to improve the signal-to-noise ratio of the backscattered image, and can also be used as a transmission detector of the handheld backscattered imager, which is used to simultaneously acquire the backscattered image and the transmitted image during the scanning process; the display screen Located directly above the handheld backscatter imager, it is used to provide a human-computer interaction interface and receive and display a stereoscopic image of the surface of the measured object; the data acquisition control circuit is used to monitor the handheld The data communication, data preprocessing, and image reconstruction of the backscatter imager are controlled and executed. The present invention is small in size, light in weight, portable and can be close to the measured object, and can scan and image the measured object from multiple angles in all directions; the trumpet-shaped shielding structure of the present invention is nested and connected with the fan-shaped pre-collimator It can effectively shield the scattering of X-rays; the photoelectric converter of the SiPM in the detector of the present invention has the characteristics of small volume and high gain, which is conducive to the miniaturization of the backscatter imager and can also control the cost accordingly; The light guide used in the detector can greatly improve the collection efficiency of the photoelectric conversion device, thereby improving the imaging resolution of the handheld backscatter imager. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial application value.

The above-mentioned embodiments only illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present invention should still be covered by the claims of the present invention.

Claims (10)

1. a handheld backscatter imager, characterized in that the handheld backscatter imager comprises: Pencil beam X-ray source, detector, static flat panel detector, display screen and data acquisition control circuit; The pencil beam X-ray source includes an X-ray generator, an X-ray fan collimator and a chopping mechanism; The X-ray generator is used to emit X-ray beams; The X-ray fan-shaped collimator is located on the front side of the X-ray generator, and includes a fan-shaped pre-collimator and a bell-mouth shielding structure, and the bell-mouth-shaped shielding structure is nested and connected to the fan-shaped pre-collimator, The fan-shaped pre-collimator is provided with a collimator slit for collimating the X-ray beam emitted by the X-ray generator into a narrow beam, and the horn-mouth shielding structure is used for shielding the scattered X-ray beam. beam of rays; The chopper mechanism is located between the detector and the bell mouth shielding structure, and includes a chopper flywheel and a driver, and the chopper flywheel is provided with chopping slits at equal angles; the driver is used to drive the chopping slits intersect alternately with the collimator slits, so that the X-ray beam emitted by the X-ray generator forms periodically reciprocating pencil beam X-rays; The detector is located at the forefront of the hand-held backscatter imager, including a photoelectric converter of SiPM and an optical system of a light guide, and the detector is used to receive the scattering signal data of the surface of the measured target; The static flat panel detector is a wireless detector, used as a backscatter expansion detector of the handheld backscatter imager, used to improve the signal-to-noise ratio of the backscatter image, or as a transmission of the handheld backscatter imager a detector for simultaneously acquiring a backscatter image and a transmission image during scanning; The display screen is located directly above the handheld backscatter imager, and is used to provide a human-computer interaction interface and receive and display a stereoscopic image of the surface of the measured object; The data acquisition control circuit is used to control and execute the data communication, data preprocessing and image reconstruction of the handheld backscatter imager. 2. The handheld backscatter imager according to claim 1, characterized in that: the handheld backscatter imager is also provided with auxiliary peripherals, and the auxiliary peripherals include a gyroscope, a SLAM camera and a word laser position marker lights; the gyroscope is located inside the hand-held backscatter imager and is used to obtain the trajectory information of the scanning plane coordinates, and in combination with the shooting guidance presented on the display screen, prompts the operator to correct the backscatter scanning attitude The SLAM camera is located at the front end of the detector, and is used for visible light forensics and video recording of the shooting process, and corrects the backscattered image through the video image; there are two laser position marker lights arranged in parallel, located on the detector The front end of the device is used to assist the operator to grasp the imaging area covered by the rays during the backscatter imaging scanning process in real time, and to correct the operation in time by observing the angles of the two columns of laser beams emitted by the two said one-character laser position marker lights The angle at which a person holds the handheld backscatter imager. 3. The handheld backscatter imager according to claim 2, characterized in that: the handheld backscatter imager is also provided with a transmission module to facilitate image upload and interaction. 4. The handheld backscatter imager according to claim 1, characterized in that: the collimator slit collimates the outgoing X-ray beam into a fan-shaped narrow beam with an angle range of 60°*1.5°, The collimator slit width ranges from 0.1 mm to 0.5 mm; the bell mouth-shaped shielding structure includes a first slit close to the fan-shaped pre-collimator and a first slit far away from the fan-shaped pre-collimator. Two slits, the angular range of the bell mouth-shaped shielding structure is 61°*2°～65°*2°, the width of the first slit is greater than the width of the collimator slit; The collimator slit is on the same axis of symmetry as the first slit and the second slit. 5. The hand-held backscatter imager according to claim 1, characterized in that: the driver drives the chopper flywheel to rotate in an indirect drive driven directly by a motor or synchronously driven by a gear; The width range of the chopping slits is 0.15mm-0.65mm. 6. The hand-held backscatter imager according to claim 1, characterized in that: a shielding mechanism is also provided between the chopper flywheel and the detector, located above the chopper flywheel, for preventing X The ray beam excites the chopper flywheel to generate characteristic X-rays, causing the detector signal response and ray leakage rate to exceed the standard. 7. The hand-held backscatter imager according to claim 1, wherein the detector further comprises: a detector front cover, a detector box, a scintillator, and a supporting readout for the photoelectric converter Amplifying circuit; the scintillator is located at the front end of the detector, the photoelectric sensor and the supporting readout amplifier circuit are located behind the scintillator, the detector front cover and the detector box The scintillator, the photoelectric sensor and the supporting readout amplification circuit are wrapped in it; the scintillator is used to absorb X-rays and convert the absorbed X-ray energy into a visible light signal, and the scintillator is a crystal scintillator or a thin-film scintillator; the matching readout amplifier circuit is used to shape, filter and amplify the voltage signal output by the photoelectric converter. 8. The hand-held backscatter imager according to claim 7, wherein the detector further comprises: a reflective layer for reducing the absorption of scintillator fluorescence by materials inside the detector to improve the For the collection effect of the photoelectric sensor on the light signal of the scintillator, the reflective layer is located in the inner cavity of the detection box and is evenly arranged, and the material is one of MgO, Al ₂ O ₃ , Tyvek, aluminum foil and PTFE film. 9. An imaging method of a hand-held backscatter imager, characterized in that the imaging method comprises: S1: start the hand-held backscatter imager, whether the self-check of the hand-held backscatter imager is normal, if not, the cause of the fault and the guidance plan to solve the fault will be displayed on the display screen, and enter the self-test completion interface according to the guidance, If so, directly enter the self-inspection completion interface, and set the scanning work parameters on the self-inspection completion interface; S2: The handheld backscatter imager includes three modes when scanning the target; one is the backscatter mode, aiming the handheld backscatter imager at the target and starting the handheld backscatter imager The scan button is used to shoot the pencil beam X-rays on the measured object for scanning; the second is the backscatter enhancement mode, where the static flat panel detector and the hand-held backscatter imager are placed on the same side without overlapping and connected to the The static flat panel detector and the handheld backscatter imager start the scanning button of the handheld backscatter imager to start the backscatter imaging scan, and the detector and the static flat panel detector simultaneously receive information from the measured target the scattering signal of the object; the third is the backscattering+transmission mode, the static flat panel detector is placed on the rear side of the measured object, and is in the whole scanning field of view of the handheld backscattering imager, connected to the Static flat panel detector and the handheld backscatter imager, start the scan button of the handheld backscatter imager to start backscatter and transmission imaging scanning; S3: Perform data preprocessing on the scattered signals received by scanning, and perform image rearrangement, and finally display the image information of the measured object on the display screen. 10. the imaging method of hand-held backscatter imager according to claim 9, is characterized in that, the imaging method of described hand-held backscatter imager also comprises the use of gyroscope, SLAM camera and a word laser position marker light Auxiliary peripherals for image correction: the parallel laser beams emitted by the two in-line laser position lights set in parallel and the pencil beam X-rays hit the target at the same time, and the two columns of parallel laser beams are located The width shows the width range that the pencil beam X-rays can cover, and the parallelism of the two columns of laser beams shows whether the detector plane is parallel to the measured object plane, which is used to instruct the operator to adjust the scanning posture and Imaging scanning range; the gyroscope can display the current shooting attitude or the plane coordinate information of the measured object, and guide the operator to scan in a straight line to avoid image bending; the SLAM camera actively photographs and images the measured object , taking pictures during the scanning process to obtain the three-dimensional coordinate information of the measured object, and the obtained three-dimensional coordinate information of the measured object can correct the image distortion caused by the scanning path through the difference value and coordinate translation.

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