Manual imaging device using the backward scattered X-radiation

Pattern description

The present application claims priority from the provisional patent application No. US 61/591 360 filed on January 27, 2012, as well as from the provisional patent applications numbers US 61/598 521 and US 61/598 576, both filed on February 14, 2012. ., as well as the provisional patent application US 61/607 066, filed March 6, 2012, all of which are referred to herein.

The present utility model relates to X-ray imaging apparatus, and more specifically, relates to X-ray imaging apparatus using detection of at least diffused X-rays.

Back-scattered X-ray techniques have been used for over 25 years to detect objects located behind the barrier that hides them, without requiring the X-ray detector to be located far from the imaged object (relative to the X-ray source). This turned out to be very beneficial for specific imaging applications, such as one-sided testing (i.e. with a detector and source on the same side of the object) of vehicles, transport containers, suitcases, and even people.

Until today, however, these devices were usually quite large and heavy due to the size and weight of the X-ray sources, due to the beam-forming mechanism that is necessary to produce the spot beam of the scanning device, as well as the detectors detecting backscattered X-rays.

A backward scattering device for detecting the structure hidden behind the wall was suggested in Japanese Publication No. 10-185842 (hereinafter referred to as the "Toshiba '842 document"), made on December 12, 1996, and also referred to herein. The apparatus described in the Toshiba '842 document can provide no more than a momentary image of the area in the scope of scanning, at a given moment, a source held by the operator.

The recent development of compact, lightweight x-ray sources operating at moderate power (typically between 1-20 W) with relatively high x-ray energy (50-120 keV), with small and highly efficient electric motors for rotary beam forming circular chopper, enabled the design and development of lightweight and compact manual imaging systems using backscatter.

In addition, prior art backscattered X-ray systems using X-ray tubes, such as those described in, for example, US Patent 5,763,866 (to Schulte), have always provided means for moving either the object or the imaging system in relative motion in attitude towards each other, along the "scan" direction, which typically means in a direction perpendicular to the plane containing the raster scanning x-ray beam generated by the circular chopper. For example, to examine an object having a vertical surface (such as a wall or piece of luggage, for example), it is scanned with an X-ray beam typically in a vertical plane, with the object being tested moved horizontally. This is typical for systems that scan luggage when the bag moves horizontally on a conveyor belt, or for systems that scan vehicles where the vehicle passes by (or through) the system, or alternatively the system is moved horizontally next to stationary vehicle. For personal scanners that use backscattered X-rays, the beam typically scans in a horizontal plane, with the source assembly displaced next to a stationary person in a vertical direction. In either case, to create a two-dimensional backscatter image, there must be relative displacement of the system and the scanned object, and this requirement typically adds significantly to the weight, size, and complexity of the imaging system.

Also known from document WO0037928 is an imaging apparatus comprising a housing, a source of penetrating radiation, completely contained inside the housing, for generating penetrating radiation, a spatial modulator, for forming penetrating radiation in a beam, for exposing an object and for deflecting the beam, and a first detector, enclosed in a housing , to generate the first signal based on penetrating radiation scattered by the content of the object being tested. However, this apparatus does not provide sufficiently accurate imaging of the defects and flaws of the examined object.

PL 70 150 Y1

The essence of the utility model is that the imaging apparatus comprising a housing having a substantially flat front wall, two side walls, a bottom wall and a top wall; b. a penetrating radiation source, contained entirely within the housing, to generate penetrating radiation; c. spatial modulator, enclosed in a housing, located between the radiation source and the front wall of the housing, for forming penetrating radiation into a beam, for irradiating the object and for deflecting the beam; d. detector, enclosed in a housing, to generate a signal based on penetrating radiation scattered by the content of the object being tested; e. the processor, enclosed in a casing, for receiving signals and generating an image of the content of the examined object based on the received signals, characterized by the fact that it further includes a f. handle, containing a beam protruding above the upper wall of the casing in a direction parallel to the front wall of the casing and away from the wall upper housing.

Preferably, the apparatus further comprises a mechanical encoder, enclosed in a housing, for detecting motion associated with the previous position of the apparatus relative to the object being tested.

Preferably, the apparatus further comprises an accelerometer, enclosed in a housing, for detecting movement associated with the previous position of the apparatus relative to the object being tested.

Preferably, the apparatus further comprises an optical sensor encased in a housing for detecting movement associated with the previous position of the apparatus. Preferably, the apparatus further comprises a friction reducing element disposed on the front of the housing adapted to provide contact between the apparatus and the object being tested.

Preferably, the friction reducing element is selected from the group consisting of wheels, castors and low friction liners.

Preferably, the apparatus further comprises a backscatter screen coupled to the apparatus by attaching it to the housing.

It is also advantageous that the backscatter screen is adapted to extend outward from the housing.

It is also beneficial that the backscatter screen is flexibly adapted to be compatible with the surface of the object being tested.

In accordance with various variations of the utility model in question, an imaging apparatus is provided. This imaging apparatus has a casing and a penetrating radiation source contained completely inside the casing to generate penetrating radiation. In addition, this apparatus has a spatial modulator for generating penetrating radiation in a beam for irradiating an object and for deflecting the beam, a detector for generating a scatter signal based on penetrating radiation scattered by the content of the examined object, a sensor for detecting camera movement relative to the previous position of the apparatus relative to the examined object . and a processor for receiving the scatter signal and for generating an image of the content of the test object based on at least the scatter signal.

The housing may be adapted to be held by one operator by the operator, and in some embodiments, the sensor may be a mechanical encoder, or also an accelerometer or an optical sensor, in reference to three examples. The processor can be adapted to modulate the intensity of penetrating radiation based on the detected camera movement.

In other variations of the subject utility model, the backward scattering imaging apparatus may also have a friction reducing element adapted to provide contact between the apparatus and the object being tested. This friction reducing element may include wheels, rollers and low friction liners.

In yet other variations, there may be one, two or more handles coupled to the housing. There may be a blockade to deactivate the penetrating radiation source if no object is detected in the specified proximity of the camera.

In alternative variants of the utility model, a permeation detector is also coupled to the apparatus. A backscatter screen can also be used, which is adapted to be folded out from the housing, where the backscatter screen can also be flexibly adapted to adapt to the surface of the object being tested.

The aforementioned features of this utility model will become more easily understood by reference to a further detailed description, developed with reference to the attached figures, in which:

PL 70 150 Y1

Fig. 1 is an exploded view of a hand-held device using backscattered X-rays according to the present utility model.

Fig. 2 schematically illustrates the use of collimation detectors to limit the detection of scattering near a radiation source in accordance with the present utility model.

Fig. 3 shows a hand-held imaging device with a detachable single-channel permeation detector according to the present utility model.

Fig. 4 shows a hand-held imaging device with a detachable multi-channel penetration detector according to the present utility model.

Figures 5A-5C show the operation with both hands of a hand-held device using backscattered X-rays according to the present utility model.

The term "image" as used in this description and in the appended protection claims refers to any multidimensional representation, be it in tangible or perceived differently or otherwise, with each of a number of places corresponding to the dimensional coordinates of the object in physical space, although not necessarily mapped to it one to one, the value of a certain characteristic is assigned. Thus, for example, a graphical display of the spatial distribution of a certain feature, such as an atomic number, in one or more colors is an image. It is also the arrangement of numbers in the computer memory or holographic center. Similarly, the term "imaging" refers to the representation of physical characteristics found in one or more images.

Distribution of penetrating radiation energy can be determined in this document, for convenience of recording, by indicating the final energy emitted (often referred to as "end-point" energy). Thus, for example, an X-ray tube that sends x-ray braking radiation, because of electrons accelerated by a potential of 100 kV, will send x-rays with less than 100 keV energy, and the spectrum of the emitted radiation can be characterized in this document as "100 keV beam", while the image of the detected scattered radiation from this beam can be referred to in this document as the "100 keV scatter image."

The terms "high Z" and "low Z" used in this description and in any attached protection claims will have relative meanings to each other, i.e. "high Z" refers to the material or image line characterizing the effective atomic number Z, which is higher than in for a material or image line referred to in the same context as "low Z".

It will now be described generally with reference to Fig. 1, backscatter imaging apparatus 100 according to the present utility model. A source of penetrating radiation 102, which may be, for example, an X-ray lamp as shown, or may be any other source of penetrating radiation particles (such as gamma rays), transmits penetrating radiation that is formed into a beam 106 by means of a beam-forming structure (or collimation), generally indicated by reference number 108. Such beam forming structures are well known in the art, and all such structures are also within the scope of the present utility model.

The beam 106 is temporarily interrupted by a wheel chopper 110, driven by the motor 109, although in practice any other means for breaking the beam 106 may be used in practice within the scope of the utility model. The mechanism used for shaping the beam 106 and for temporary interruption as well as spatial scanning , beam 106, may be referred to in this document as a spatial modulator. The beam 106 strikes the surface 120 of the test object 121 outside the apparatus 100. The penetrating radiation 124 scattered by the inside content 118, or the content behind the surface 120, is detected by one or more backscattering detectors 122, each of which is connected to a processor 130 to generate a backscatter image for the object 121. The detectors 122 can use a wavelength optical cable that uses scintillation, and thus thin-profile detectors can be used outside of the configuration in the assembly, with respect to the housing 142. The imaged object 121 can be an internal building wall, lined with stone, or a cage or a crate, while the numeral 120 indicates the surface of such a wall, cage or crate.

According to the present utility model, the imaging apparatus 100 scans an X-ray beam 106 on a single linear path 125 (e.g., along a horizontal line) using well-known scanning techniques based on rotating

PL 70 150 Y1 slots relative to the defined gap etc. It should be understood that the linear scan path may be arcuate or otherwise curvilinear within the scope of the subject utility model. Meanwhile, the operator moves the system in the "scan" direction 127, substantially perpendicular to this plane. (In the example illustrated in Fig. 1, the scanning direction is a vertical direction.) This means that this system does not have to include mechanisms to ensure relative movement, which makes this system simpler, lighter and much more compact.

To ensure stability when this system is used, one or more friction-reducing elements 123 may be built into the front of the device, which allows the system to be pushed to the surface 120 of the object 121 that is imaged. The friction reducing element 123 may include, for example, a set of wheels, rollers or low friction inserts.

Referring still to Fig. 1, a miniature X-ray tube (with an emission of approximately 10 W, with an anode potential of approximately 70 kV) can serve as a source of penetrating radiation 102. As shown, circular chopper 110, driven by motor 109, generates a spot x-ray beam 106 of the scanning device. In the embodiment shown, a housing 142 with two handles 140 and 141 is used, so that the operation of the device 100 with one hand or two hands is facilitated, depending on which is easier for the operator.

According to a preferred embodiment of the utility model, the center of mass of the imaging device 100 is configured such that the front surface 126 of the device remains in full contact with the surface 120 of the object being scanned, even if the device is held only by the upper handle. This reduces the torsional forces acting on the operator's arm and wrist, reduces fatigue and facilitates the use of the device.

One of the limitations associated with relying on the operator to provide relative movement in the "scan" direction is the variation in scan speed and direction that will occur due to the operator's lack of experience or fatigue, or due to surface irregularities. According to one embodiment of the utility model, the variability of the scanning speed can be compensated by the use of one or more sensors 145 or position encoders that allow to deduce the current position relative to the previous position in such a way that the aspect ratio can be dynamically corrected sequentially for each scan line. For example, if an operator slows relative movement during a portion of the scan, the encoder or sensor informs the software executed by the processor 130 that this has occurred, and the imaging software can then average several lines together so that no distortion appears in the image displayed to the operator . Therefore, if the operator speeds up the movement during the scanning part, the software can interpolate additional lines to the image in such a way that no image distortion is noticeable. In addition, encoders can be used to correct for variations in scanning direction, improving the image, for example if adjacent image bands are not completely parallel to each other. Encoders or position sensors may include, but are not limited to, an optical or mechanical mouse, encoders coupled to wheels or rollers, or accelerometers that monitor changes in scanning speed.

According to an additional embodiment of the utility model, it is possible to dynamically change the anode current of the X-ray tube 102, depending on the instantaneous scanning speed of the device. For example, if the scanning speed is reduced by a factor or two, the anode current can be reduced by a factor or two. This means that even if the scan would require twice as long, the total radiation per scan and acting on the operator and the environment remains the same, which increases the security of the device.

The use of position sensors or accelerometers 145 also makes it possible to "stitch" together images from a smaller scan area to create a larger image with a substantially larger format. For example, the operator can first scan a 12-inch wide vertical wall strip, and then move to an adjacent vertical strip. Due to the fact that the system knows the location (at least relative to the starting point, but not necessarily the absolute position) of the X-ray beam at any given time, images corresponding to each belt can be combined with each other by a computer or system controller 130 to create one image containing several belts. Stitching algorithms

PL 70 150 Y1 various images are known in the art, for example in Szelinski's "Image Alignment and Stitching: A Tutorial", Technical Report MSR-TR-2004-92, Microsoft Corporation, in the document Paragios (ed.) " Handbook of Mathematical Models in Computer Vision ', pages 273-92 (2005).

Another important set of considerations associated with the hand-held device 100 is radiation protection. According to the utility model, the operator and other persons in the immediate vicinity can be secured using one or more of the following locking mechanisms:

1. The detected backscatter signal is continuously monitored by the processor 130, and if it falls below a certain predefined threshold, it means that the front surface 126 of the device is not in close proximity to the wall or other object 121, which is an undesirable circumstance;

2. A sensor (mechanical, capacitive, etc.) 128 may turn off x-rays if the front surface of the device is not adjacent to a solid surface;

3. A sensor (optical, acoustic, etc.) can measure the distance of the device from the nearest object, and also deactivate x-rays, if no object is detected at a certain distance; and

4. A motion sensor, such as accelerometer 145, can deactivate x-rays if the device is stationary and not moving.

In addition to blocking, another aspect of the utility model uses fold-out scatter screens 129 that limit the radiation dose to the operator. Screen 129 may be rigid or flexible to allow use of the system in tight corners. Rigid covers can be made of thin lead, tungsten or steel (for example). Flexible shielding materials include the use of flexible plastic, impregnated with lead or tungsten powder.

Referring now to Fig. 2, from the first beam-illuminated object 120, which object will in many cases be a blackout barrier, such as a room wall or door, a plurality of back-scattered X-rays 124 that are detected in the backscatter detectors 122 device. This limits the ability to observe objects 118 behind the barrier because these "near field" X-rays tend to blur the image and limit the contrast of deeper objects. Because near-field scattering originates from a point close to the device, it is preferable that the backscattering detectors are physically collimated in such a way that the radiation from the near-field 202 is blocked before entering the detectors, with detection of near-scattering only. fields 204 as shown in Fig. 2. This results in an improved signal-to-noise ratio (SNR) for imaging deeper objects. Collimation can be performed using one or more thin blades 200 of x-ray absorbing material placed in front of backscatter detectors (e.g. lead, tungsten, brass or steel), positioned and angled so that near field radiation is unable to pass between the blades and into the detector.

In addition to the use of standard collimation techniques, the technique known as "active collimation" in this hand-held device can be used to simultaneously detect diffuse X-ray radiation from both near and far fields. This technique is described in patent application US 13/163 854, filed June 20, 2011, which is referred to in this document.

In addition to performing backscattered x-ray imaging, a hand-held imaging device 100 using backscatter can also be used to generate diffusion images. This requires that the penetration detector be placed behind the object being imaged. Due to the fact that the device uses an x-ray beam 106 of the scanning device (shown in Fig. 1) instead of a cone or fan beam, the detector does not have to be a costly pixel detector, but it can be a single-channel detector that covers enough area to capture all of the x-ray radiation transmitted through the object. This detector may be similar to a backscatter detector, but includes a scintillator that is optimized to detect x-rays in the original beam instead of scattered x-rays. This configuration makes it very compact

PL 70 150 Y1 and a lightweight detector design that improves the device's portability. For example, this device can then be used by a sapper unit to scan suspicious objects (such as an abandoned package) under both backscatter and penetration modalities, which significantly improves the detection capabilities of explosive devices.

In Fig. 3 one embodiment of the device is shown, in a single-channel penetration mode of a one-dimensional penetration detector 300 attached to the device. In this case, the penetration detector 300 is attached to the hand-held device 100 and intercepts the transmitted beam when it passes in a horizontal plane on the distal side of the object being tested. The interference detector 300 may be detachable, as a result of which the device may be used with or without interference imaging. This form of utility model can advantageously be used, for example, for imaging the continuous longitudinal course of the pipe. With the permeation detector attached, the device is suitable for testing objects, such as pipes or wooden beams, for flaws or fatigue defects, with both backscatter and penetration images being generated simultaneously.

According to a last embodiment, enabling the device to perform diffusion imaging, a removable or switchable beam forming mechanism 108 (illustrated in Fig. 1) is used that allows the device to switch from generating a scanning spot beam to generating a fan beam. In this fan beam mode, the imaging device 100 can be connected to a detachable, high resolution, segmented penetration detector beam 400, which has a plurality of small detector elements 402, as shown in Fig. 4. This embodiment of the utility model illustrated in Fig. 4 is particularly advantageous for high resolution imaging of long structures such as pipes or wooden beams.

Many configurations of this utility model utilize various configurations for backscatter detectors to improve performance or provide additional information. Some of them are listed below as an example:

1) Fold-out detectors to provide a larger detection area. This allows for a very compact device in terms of balance and mobility, but also allows for better imaging efficiency. This is especially useful when the distance must be larger due to space constraints or because a large area has to be scanned and scanning from a larger distance is faster. Such fold-out detectors preferably provide additional shielding to the operator against scattering, and also optionally contain additional material to improve their shielding capabilities, such as lead or tungsten impregnated plastic.

2) Asymmetrical detector size or placement to provide information regarding the depth of the object being imaged, and thus to provide some 3D information, as described in US Patent 6,282,260, which is incorporated herein.

3) Additional portable detector modules may be located near the object 121 to be scanned. These modules can be independent in terms of power supply and send their output signals to the data acquisition system wirelessly (including optically) or they can have cables that can be connected to a hand-held device or docking station.

Depending on the objects being scanned, the required scan times or the distance between the device and the object being imaged may be beneficial to be able to dynamically change the imaging resolution of the system. This is most easily achieved by changing the width of the collimator, which determines the size of the beam along the scanning direction (this is the beam dimension perpendicular to the scanning direction and parallel to the scanning direction of the device over the object). If the device is very close to the object being scanned, reducing the collimator width twice will increase the resolution by a factor of two in the scanning direction. This also provides the added benefit of reducing the dose per unit of time for the environment.

For example, for the initial high scan speed of an object, the collimator width can be increased, resulting in a larger beam flux (i.e. faster scanning), but a lower resolution. If something suspicious is detected in the first low-resolution image, you can perform a secondary scan with a higher resolution, with a limited collimator width. The collimator width can be manually adjusted with a mechanical lever, or alternatively, the collimator width can be electrically adjusted using electromechanical actuators or stepper motors.

PL 70 150 Y1

One of the limitations of a hand-held battery-operated device is often the length of time the device can be used before it requires recharging the battery. Due to the fact that the X-ray tube described in this utility model consumes only about 10 W electric current on the anode, the total energy consumption of the device can be quite low, and the operating time using a lithium-ion battery can be quite significant.

However, for applications that require multiple scans or large areas, it may be beneficial to use a larger power source that is not installed in this handheld device. On the operator's belt or in a backpack worn by the operator, or in a separate module placed on the door, for example, a wheeled trolley may be fitted with a battery or other type of power supply device (e.g. fuel cell).

According to another embodiment of this utility model, a portable or non-portable docking station is used in which a hand-held device is placed. This docking station can perform one or more of four main functions:

1) Supports the device and moves it at a controlled speed for high resolution imaging using backscatter and / or diffusion;

2) Provides additional power to extend operating time;

3) Recharges the device's battery; or

4) Provides electrical connections for loading images and / or diagnostic information.

In certain variations of this utility model, illustrated in Figs. 5A-5C, the device housing 142 has a variation in which the device housing has both an upper handle 141 and a lower handle 140, wherein the housing and handles are indicated in Fig. 1. is to hold the device by the lower handle for scanning areas that are high above the ground, and also by the upper handle for scanning areas near the floor. It is also designed so that the system can perform a search in a single continuous displacement from a point as high as the operator can comfortably reach (as illustrated in Fig. 5A) down to the ground (as illustrated in Fig. 5C) , using the following sequence:

1) One hand only on the lower handle (upper part of the scan) as in Fig. 5A;

2) Both hands on both handles simultaneously (middle part of the scan) as in Fig. 5B;

3) One hand only on the upper handle (lower part of the scan) as in Fig. 5C.

The above operating mode can advantageously minimize operator fatigue by distributing the load between two hands, as well as maximizing the scanning area into one vertical search by the device.

Although the forms depicted in this document include specific combinations of system components, it should be understood that these components may be combined in other ways to accomplish the same purpose of x-ray imaging. In addition, individual features of the device may be compatible with the elements separately specified in some claim. The utility model variations described in this document are intended to be illustrative only; changes and modifications will be apparent to those skilled in the art. All such changes and modifications are intended to be included in the scope of the utility model in question, as defined in the attached protection claims.