X-ray inspection using wavelength-shifting fiber-coupled scintillation detectors.

(54) Title: X-RAY INSPECTION USING SCINTILATION DETECTORS COUPLED WITH WAVE LENGTH DISPLACEMENT FIBERS.

(54) Title: X-RAY INSPECTION USING WAVELENGTH-SHIFTING FIBER-COUPLED SCINTILLATION DETECTORS.

(57) Summary

A detector and methods for inspecting material on the basis of the scintillator coupled by means of a wavelength shift optical fiber to one or more photodetectors, with a temporal integration of the photodetector signal; a non-pixelated volume of scintillation medium converts the incident penetrating radiation energy into scintillation light that is extracted from a scintillation light extraction region by means of a plurality of optical waveguides; This geometry provides efficient and compact detectors that so far allow unavailable geometries for return scatter detection and for incident radiation energy discrimination; Additional power resolution transmission settings are allowed, such as mismatch and mismatch compensation.

(57) Abstract

A detector and methods for inspecting material on the basis of scintillator coupled by wavelength-shifting optical fiber to one or more photo-detectors, with a temporal integration of the photo-detector signal. An unpixelated volume of scintillation medium converts energy of incident penetrating radiation into scintillation light which is extracted from a scintillation light extraction region by a plurality of optical waveguides. This geometry provides for efficient and compact detectors, enabling hitherto unattainable geometries for backscatter detection and for energy discrimination of incident radiation. Additional energy-resolving transmission configurations are enabled as are skew- and misalignment compensation.

Institute

Mexican Property

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PATENT TITLE NO. 337476

Owner (s): AMERICAN SCIENCE AND ENGINEERING, INC.

Address: 829 Middlesex Turnpike, Billerica, Massachusetts, 01821, USA

Name: X-RAY INSPECTION USING SCINTILATION DETECTORS COUPLED WITH WAVE LENGTH DISPLACEMENT FIBERS.

Classification: lnt.CI.8: G01T1 / 20

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ANATOLI ARODZERO; JOSEPH CALLERAME; DAN-CRISTIAN DINCA; RAJEN ií «

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US

US

February US from February 14 to March 6, 2012

61/598,521

61/598,576

61/607,066

Validity: Twenty years Date of Sale: 4 of f &lt;

The reference patent grants ct ntation of the

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title it || ace based on the provisions 3 Industrial officer.

pleasurable, the entities I fundamentale l °?

In accordance with article 23 of&gt; i Law of the Pi counted from the date of prior rights.

twenty years impi 'a to maintain

6th fractions III and 7 'bis 2 of

Who subscribes the presei

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26/01/2004,

25/01/2006, 06.

ey of the / 05/1999, fraction V subsection a), 4th and 12th fractions I and III of the Regulation of the Mexican Institute of Industrial Property (DOF 14/12/1999, amended on 07/01/2002, 15 / 07/2004, 07/28/2004 and 09/07/2007); articles 1, 3, 4, 5, section V inclsoa); l6 sections I and III and 30 of the Organic Statute of the Mexican Institute of Industrial Property (DOF 12/27/1999, amended; 10/10/2002, 07/29/2004, 08/04/2004 and 09/13/2007); 1, 3 and 5 subsection a) of the Agreement that delegates powers to the Deputy Directors General, Coordinator, Divisional Directors, Holders of the Regional Offices, Divisional Deputy Directors, Departmental Coordinators and other subordinates of the Mexican Institute of Industrial Property. (DOF 12/15/1999, amended on 02/04/2000, 07/29/2004, 08/04/2004 and 09/09/2007).

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Issue Date: March 4, 2016

THE DIVISIONAL DIRECTOR OF PATENTS

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•TO'

NAHANNY CANAL REYES

Arenal No. 550, Floor i,: I heard. Pueblo Santa María Tepepan,

Xochimilco, CP 16020,

Mexico City 55) 53 34 07 00 www.imni.gob.mx

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MX / 2016/18345 _______

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X-RAY INSPECTION USING DETE * Z * · Urt «nvt'icuiv

MOVS1RJAL

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SCINTILATION COUPLED WITH FIBERS OF DISPLACEMENT OF

WAVELENGTH

This application claims priority of the Applications for

US Provisional Patent, Serial Nos. 61 / 598,521 and 61 / 598,576, both filed on February 14, 2012, and US Provisional Patent Applications, Serial No. 61 / 607,066 filed on March 6, 2012, all applications are incorporated herein by reference. .

FIELD OF THE INVENTION

The present invention relates to fiber-coupled scintillation detectors and methods for their manufacture, and to x-ray inspection systems and methods employing fiber-coupled scintillation detectors for efficient detection of x-rays.

BACKGROUND OF THE INVENTION

Radiation fiber and particle coupled scintillation detectors have been used for the past 30 years. In some cases, the scintillator is pixelated, consisting of discrete scintillator elements, and in other cases, other stratagems are used (such

IΜ ΡI rNSTnvro mezjcwo Oí tA * K0 «£ G. \ O lAZDUSTiilMi (orthogonally crossed coupling fibers) in order to provide spatial resolution. Examples of fiber coupled scintillation detectors are provided in US Patent Nos. 6,078,052 (for DiFilippo) and 7,326,9933 (for Katagiri et al.), Both of which are incorporated herein by reference. The detectors both described by DiFilippo and Katagiri et al. employ Wavelength Displacement Fibers (WSF) so that light that is re-emitted by the fiber core material can be conducted, with low attenuation, to photo-detectors that are placed in a convenient location, often distant from your own scintillator. Spatial resolution is of particular value in applications such as neutron imaging. Spatial resolution is also paramount in the Fermi Large Area Space Telescope (formerly known as GLAST) where a highly efficient segmented scintillation detector employs WSF reading for detection of high energy cosmic rays, as described in Moiseev , ef al, High efficiency plastic scintillator detector with wavelenght-shiñing fiber readout for the GLAST Large Area Telescope, Nucí, Instr. Meth. Phys. Res A, vol, 583 pp. 372-81 (2007), which is incorporated herein by reference.

Due to the contexts where fiber coupled scintillator detectors have been employed to date, all known fiber coupled scintillator detectors have counted pulses produced by individual particle interactions (photons or massive particles) with

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OF THE INDUSTRIAL ROYALTY

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the scintillator, thus allowing the energy of the incident particle to be determined based on the cumulative flow of light that the scintillator re-emits.

The detection requirements of X-ray return scattering inspection systems, however, are completely different from the requirements addressed by existing fiber-coupled scintillation detectors. Return dispersion x-ray inspection systems have been used for more than 25 years to detect hidden organic materials inside luggage, cargo containers, vehicles and people. Since organic bulk materials preferably scatter x-rays (via Compton scattering) rather than absorb them, these materials appear as brighter objects in return scatter images. While incident x-rays scatter in all directions, sensitivity far exceeds spatial resolution as a requirement, and in most scattering applications, the detector's spatial resolution is of no concern, as the resolution it is governed by the incident beam rather than by detection.

The specialized high-area and high-sensitivity detection requirements presented by x-ray scattering systems are particularly troublesome in the case of conventional scintillation detectors 100 of the type shown in a lateral cross section in Figure 1A and in a section front cross section in figure 1B. An example of such a detector is described in US Patent No. 5,302,817.

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MEXICAN INSTITUTE OF PROPERTY

INDUSTRIAL

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(for Yokota) and is incorporated herein by reference. Typically, a light-tight box 102 is aligned with scintillation screens 103 where Incident x-ray radiation 101 is converted to scintillation light, typically UV, wavelength, visible or longer, portions of the electromagnetic spectrum. (EM, for its acronym in English). Photomultiplier tubes (PMTs) with large photocathode area 105 are coupled to receive scintillation light through holes 108. One problem is that a fraction of the scintillation light originating within the screen is transmitted from the screen in the enclosed volume. The rest of the scintillation light is lost in the screen material. Scintillation screens 103 are designed to maximize the fraction of light emitted, which is equivalent to ensuring a large transmission coefficient T for the interface between screen 103 and the medium (usually air) that fills the volume of the detector. However, in a conventional return scatter detector of the type shown in Figures 1A and 1B, the scintillation displays 103 should also serve as good reflectors because the scintillation light, once emitted in the volume of the box 102 , normally it needs multiple reflections until it reaches a photo-detector 105. In this way, the reflection coefficient R on the screen surface must also be large, however, since the sum of T and R is limited to be unity, both T and R cannot be maximized simultaneously , and a balance must be found. As a result, the light collection efficiency

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of the r.onvfinnional return scatter detector is inherently low, with only a few percent of the scintillation light generated collected on the photodetectors.

For an imaging detector, statistical photon noise is calculated in terms of the photons absorbed by the detector and used to generate the image. Any photons that pass through the detector without being absorbed, or even those that are absorbed without generating image information, are discarded and do not contribute to image noise reduction. Since photons cannot be subdivided, they represent the fundamental quantum level of a system. It is common practice to calculate statistical noise in terms of the smallest number of how many used to represent the image anywhere along the imaging chain. The point along the imaging chain where the lowest quanta are used to represent the image is called a quantum heatsink. The noise level in the quantum heatsink determines the noise limit of the imaging system. Without increasing the number of information carriers (i.e., how many) in the quantum heatsink, you cannot improve the system noise limit. Poor light collection can possibly create a secondary quantum sink, which is said to limit the fraction of incident x-rays that result in the PMT stream. In addition, it will increase the noise of the image. The efficiency of light collection can be improved by increasing the sensitive area of ​​the photodetectors, without

1F1

MEXICAN

INSTITUTO MEXICANO O £ LA FXOPISDAD iNDUSTKJAi However, the road to efficiency is costly.

The structure of the screen employed in prior art x-ray scintillation detectors is now described with reference to Figure 2. A layer of composite scintillator 202 is sandwiched between a backsheet 204 for structural support and a transparent protective film and thin 206 that is made of polyester, for example. The composite scintillator normally consists of micro-sized inorganic crystals in an organic matrix or resin. Crystals are the current scintillation material. Barium fluorochloride (BaFCI or BFC) or gadolinium oxysulfide (Gd202S, or Gadox) doped with rare earth elements are common choices for this. The stopping power of the screen is determined by the thickness of the composite scintillator layer 202, which is normally measured in milligrams of the scintillator glass per unit area. Since inorganic scintillators (such as BFC or Gadox) suffer from high self-absorption, the composite scintillator layer has to be kept quite thin in order to extract a good fraction of the scintillation light. This limits the useful stopping power of the display and makes it suitable only for x-ray detection with energies up to approximately 100 keV.

Therefore, it may be advantageous to have a scintillation detector for x-ray scattering detection applications that provides more efficient scintillation light extraction, collection, and detection.

scintillation normally

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As pmoipium was briefly discussed, —Rip wavelength shift (WSF) fibers have long been used for scintillation detection. The wavelength displacement fibers consist of a relatively high refractive index core, surrounded by one or more lower refractive index coating layers. The core contains wavelength displacement material, also referred to as a dye. Scintillation light entering the fiber is absorbed by the dye, which in turn emits light with a longer wavelength. The longest wavelength light is emitted isotropically in the fiber material. Total internal reflection traps a fraction of that light and drives it over long distances with relatively low loss. This is possible, as described with reference to FIG. 3, because the dye absorption 304 and emission wavelength scales 302 do not effectively overlap so that the displaced wavelength light is not re-absorbed. The captured fraction is determined by the ratio of the refractive indices on the fiber surfaces. An additional advantage of WSF is that the wavelength shift can put scintillation light 306 on the sensitive wavelength scale of the photo-detector (PMT, Silicon Photomultiplier, (SiPM), or Photon Counter Multi Pixel (MPPC), or otherwise).

Scintillator structures have been produced using many manufacturing technologies, including, for example, die casting, injection molding (as described by Yoshimura et al., Plastic scintillator produced by the injection-molding technique, Nucí. Instr. Meth.

Phys. Res. A. vol. 406, pp 435-41 (1998) and extrusion (as described in

US Patent No. 7,067,079, to Bross, et al.,) The references of which are incorporated herein by reference.

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BRIEF DESCRIPTION OF THE INVENTION

In accordance with various embodiments of the present invention, systems and methods are provided that apply fiber-coupled scintillation detectors to problems in transmission X-ray inspection and return scattering.

For annotation convenience, a wavelength shift fiber coupled scintillation detector may be referred to herein as a Sc-WSF detector.

In a first embodiment of the present invention, a penetrating radiation detector is provided having a non-pixelated volume of scintillation medium to convert incident penetrating radiation energy to scintillation light. The detector has multiple optical waveguides, aligned substantially parallel to each other over a scintillation light extraction region that is contiguous with the non-pixelated volume of the scintillation medium. Optical waveguides guide light derived from scintillation light to a photo-detector to detect photons

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guided by waveguides and to generate a signalTTtnl iklmitor _____

In other embodiments of the present invention, the detector may also have an integration circuit to integrate the detector signal for a specified amount of time.

In an alternative embodiment of the invention, a penetrating radiation detector is provided having a scintillation medium volume to convert the energy of the incident penetrating radiation into scintillation light and a plurality of optical waveguides, aligned substantially parallel to each other. yes on a scintillation light extraction region contiguous with the volume of the scintillation medium. Optical waveguides guide light derived from scintillation light to a photo-detector that generates a signal from the detector. Finally, an integration circuit to integrate the detector signal for a specified period of time.

In additional embodiments of the invention, the optical waveguides in the above detectors can be adapted for scintillation light wavelength shift and, more particularly, can be wavelength shift optical fibers. The scintillation medium may include a lanthanide-doped barium halide such as barium fluorochloride. The photodetector may include a photomultiplier.

In even further embodiments of the invention, the square of the thickness of any of the above detectors, divided by the area of ​​the detector, may be less than 0.001. At least one of the plurality of

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Mexican INSTITUTE OF THE PXOflEDAO INOUSTKIAL

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Waveguides may be devoid of coatings and the medium du eiscinliluiuiúQ ^ s ^ may be characterized by a refractive index of the value lower than a refractive index characterizing the waveguide. The optical waveguides can be placed in multiple parallel planes, each of the parallel planes containing a subset of the plurality of optical waveguides.

In other embodiments of the invention, the detector may have a plurality of scanning medium layers encountered successively by an incident beam, and the layers may be characterized by spectral sensitivities other than the incident beam. Alternate binder layers may include Li⁶F: ZnS (Ag) alternating with at least one of fiber-coupled BaFCI (Eu) and fiber-coupled BaFI (Eu). A first of the plurality of layers of the scanning medium may be a detector coupled with wavelength displacement fibers preferably sensitive to lower energy X-rays and a last of the plurality of layers of the scanning medium may be a plastic scanner.

The segments of the scanning medium can be placed in a plane transverse to the propagation direction of an incident beam, and can be coupled differently to photodetectors by means of optical fibers.

In accordance with another aspect of the present invention, a method of making a scintillation detector, the method comprises extruding a cover of scintillation material around a guide wire.

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MEXICAN INSTITUTE OR £ LA FKOFI AGE

INDUSTRIAL

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optical wave, and, in a particular embodiment, the rfe guide optical wave or one wavelength shift optical fiber.

In an alternative embodiment, a method of detecting scattered X-ray radiation has the steps of;

to. providing a detector characterized by a plurality of individual read segments; and

b. adding a signal from a subset of the individual read segments, where the subset is selected on a relative signal-to-noise basis.

In another aspect of the invention, a method is provided for detecting scattered x-ray radiation. The method has the steps of:

to. providing a detector characterized by a plurality of individual read segments; and

b. summing a signal from a subset of the individual read segments, where the subset is selected based on a known position of a primary light beam.

A mobile x-ray inspection system is provided in accordance with another embodiment. The inspection system has an x-ray radiation source that is placed in a transport that has a platform and members that contact the ground, and a fiber-coupled scintillation detector deployed outside the transport during the inspection operation to detect x-rays that have interacted with the inspected object.

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MEXICAN INSTITUTE ÜE THE PROPERTY

INDUSTRIAL

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The mobile x-ray inspection system may also have a fiber-coupled scintillation canopy detector deployed above the inspected object during the course of the inspection, and the canopy detector can slide out of a transport ceiling prior to Inspection operation. There may also be a skirt detector deployed below the transport platform, and a ceiling detector for detection of spaces above the transport, as well as segments of the substantially horizontally and substantially vertically coupled fiber-coupled scintillator detector. The segments of the substantially horizontally and substantially vertically vertical fiber-coupled scintillator detector can be formed into an Integral structure.

In accordance with another aspect of the present invention, an apparatus for detecting incident radiation in the apparatus is provided, the apparatus comprising:

to. a plurality of substantially parallel active collimation vanes comprising scintillation detectors coupled with radiation sensitive wavelength displacement fibers to generate at least a first detection signal;

b. a rear wide area detector for detecting radiation passing between the substantially parallel active collimation blades of the plurality of active collimation blades and generating a second detection signal; and

c. a processor to receive and process the first and

MEXICAN INSTITUTE OF PROPERTY

INDUSTRIAL second detection signals. --According to an alternative embodiment of the Invention, a top-down imaging system is provided to inspect an object that is placed on an underlying surface.

The top-down imaging inspection system has a substantially downwardly directed x-ray source and a linear detector arrangement that is positioned within a ledge above the underlying surface. The linear detector arrangement may include scintillation detectors coupled with wavelength displacement fibers.

In accordance with another aspect of the invention, an x-ray inspection system is provided to inspect a underside of a vehicle. The x-ray inspection system has a substantially upward-directed x-ray source coupled to a chassis and a scintillator detector coupled with wavelength displacement fibers that is placed on the chassis to detect x-rays scattered throughout the vehicle. and for objects hidden under or inside the vehicle. The chassis can be adapted to be maneuvered under the vehicle by at least one engine and one manual control.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features of the invention will be more readily understood by reference to the following detailed description, which is taken

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ENDUSTITAL

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with reference to the attached drawings, where:

Figures 1A and 1B show front and side cross-sectional views, respectively, of a prior art box-type scintillation detector.

Fig. 2 is a schematic view of a screen of the prior art scintillator.

Figure 3 shows spectral relationships between scintillation light and typical absorption and emission spectra of wavelength displacement fibers.

Figure 4 is a schematic perspective view of an arrangement of the wavelength displacement fibers sandwiched between the scintillator material, in accordance with one embodiment of the present invention.

Figure 5 is a schematic cross-sectional view of an arrangement of wavelength displacement fibers embedded within a matrix of scintillator material, in accordance with one embodiment of the present invention.

Figure 6A is a perspective view of a cylindrical scintillator extruded around a WSF, in accordance with an embodiment of the present invention.

Figure 6B is a schematic drawing of a system for extruding a cylindrical scintillator around a WSF, in accordance with an embodiment of the present invention.

IMPI

MEXICAN INSTITUTE Dt LA ERONEDAD

INDUSTRIAL

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Figure 6C is a cross-sectional view of an extruder for co-extruding a cylindrical scintillator with a WSF, in accordance with an embodiment of the present invention.

Figure 7 is a schematic cross section of a multiple row scintillation detector of WSF, in accordance with an embodiment of the present invention.

Figure 8 is a top view of a wavelength shift fiber coupled scintillation detector in accordance with an embodiment of the present invention.

Figure 9 shows roof and skirt return dispersion detectors, stored in accordance with the embodiments of the present invention, while Figure 10 shows the same detectors deployed during the course of inspection operations.

Figure 11 shows an awning detector and a skirt detector for use with a return dispersion inspection system in accordance with the embodiments of the present invention.

FIG. 12 is a schematic cross-sectional view of a stack of scintillator layers for use with a high energy x-ray transmission detector, in accordance with one embodiment of the present invention.

Figures 13A and 13B show a layered transmission detector within a 5.08 cm high speed reducer, in accordance with an embodiment of the present invention, while Figure

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13C shows a cross section of the assembly of hcHeet © wosedad.Q ^ n ,.

the structure of the speed reducer.

Figure 14A shows a perspective view of a segmented x-ray transmission detector for measuring the distribution of detected intensity across the width of an x-ray beam, in accordance with one embodiment of the present invention, while the Figures 14B and 14C show a final cross section and a typical beam profile of the detector of Figure 14A.

Figure 15 is a cross sectional view of a scintillation detector with multiple energy resolution, in accordance with an embodiment of the present invention.

Figure 16 shows a multilayer scintillation detector for detecting both x-rays and thermal neutrons, in accordance with an embodiment of the present invention.

Figure 17 shows a perspective view of a detector with active collimators.

Figures 18A and 18B show perspective and cross-sectional views of a WSF detector used as an active collimator in accordance with an embodiment of the present invention, and Figures 18C and

18D show an arrangement with independent readings separated by a light-tight x-ray absorber to distinguish radiation colliding with each face, in accordance with a further embodiment of the present invention.

IMPI

MEXICAN INSTITUTE OF INDUSTRIAL PROPERTY

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Figures 19A and 19B show multiple detectors folded out of a portable scanner, in stored and deployed conditions, respectively, in accordance with an embodiment of the present invention.

Figures 20A and 20B show a return dispersion unit which, by virtue of the Sc-WSF detectors according to the present invention, can be slid under a vehicle for inspection under the chassis.

Figures 21A and 21B show the. use of a right angle combination of detectors based on Sc-WSF technology in conjunction with a mobile inspection system and in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the embodiments of the present invention, the optical coupling of the scintillator material to the optical waveguides and more particularly to the wavelength displacement fibers, advantageously allows the objectives that include those characteristics specific to the X-ray scattering detection demands.

Definitions:

The term image must refer to any representation ί:

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unidimensional or multidimensional, either in tangio form or in some other perceptible form, or in another way, whereby a value of some characteristics (such as the fractional intensity transmitted through a column of an inspected object crossed by an incident beam, in the X-ray transmission imaging case) relates to each of the plurality of locations (or vectors in a Euclidean space, typically R²) that corresponds to the dimensional coordinates of an object in a physical space, although not necessarily mapped one by one in it. An image may comprise an arrangement of numbers in a computer memory or holographic medium, likewise, the formation of images refers to the representation of a physical characteristic established in terms of one or more images.

The terms of spatial relationship, such as top, bottom, top, bottom, and the like, can be used for ease of description to describe the relationship of one element to another, as shown in the figures. It should be understood that said terms of spatial relationship are intended to encompass the different orientations of the apparatus in use or operation in addition to the orientation described and / or shown in the figures.

Where an element is described as being on, connected to, or coupled to another element, it may be directly on, connected, or coupled to another element, or alternatively, one or more intermediate elements may be present, unless otherwise specified.

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INSTITUTO MEX / C?, NO DE LA PXOHEU *!}

INDUáfRiÁL

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The terminology used herein is intended to describe particular modalities and is not intended to be limiting. The singular forms one, one, and the / are intended to also include the plural forms.

WSF detectors

Referring first to FIG. 4, in one embodiment of the invention, a layer of closely spaced parallel wavelength displacement fibers 400 is sandwiched between the two layers 403 of the composite scintillation screen. The preferred scintillator material is europium doped barium fluorochloride (BaFCI: Eu), although other scintillators, such as BaFLEu or other lanthanide doped barium mixed halides (including, by way of further example, BaBrLEu and BaCskEu), can be use within the scope of the present invention. Since scintillator materials employed for x-ray detection normally exhibit very strong self-absorption of scintillation photons, the modalities according to the present invention advantageously allow unusually large volumes of scintillator 403 to be used while it still efficiently couples to the scintillation signal.

An advantage of using the composite scintillation screen in the present application is that it allows extrusion fabrication of a fiber-coupled scintillation detector.

Composite Scintillator 403 is structurally supported

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by the outer layers 404 of plastic, or some other material, 'piüpól'óioriaridü' mechanical support. The optical contact between the fiber coating 401 and the composite scintillator 403 is established by filling the voids with index compatibility material 405 of a suitable refractive index that is transparent to scintillation light. The refractive index of the filler material is chosen to optimize the collection of primary light photons in the WSF and the capture of wavelength displaced photons in the fiber. Filler material 405 may be optical grease or optical epoxy, for example although any material is within the scope of the present invention.

Upon incidence of x-ray photons, scintillation light emitted by scintillator 403 is coupled by coating 401 to core 407 of the respective fibers, displaced downward in frequency (i.e., redshifted) and propagated to one or more photodetectors 805 (shown in Figure 8, for example). Light from the fiber cores 407 is converted to a current by the 805 photo-detector, and the current is integrated over a time interval, typically on the scale of 1 to 12 ps, to obtain the signal strength for each pixel. Integration of the detector signal can be accomplished by means of an integration circuit (not shown), such as an integration preamplifier, for example.

Referring now to Figure 5, the wavelength displacement fibers 400 are embedded in the scintillation screen matrix

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lNiri FUTO MEXICANO

ÜE Industrial PROPERTY

503. The embedding of the WSF in the scintillation medium creates the optical contact.

In yet another embodiment of the invention, which is now described with reference to FIG. 6A, composite binder material 603 is applied as a coating or cover around a WSF 601 with core 602. This application by itself leads to a extrusion type manufacturing procedure and allows the most effective use of expensive material of the 603 binder. Scratcher material 603 is sealed with a protective layer 604 that also acts as a reflector for the scintillation light. Within the scope of the present invention, the coating can be omitted when the scintillator has a lower refractive index than the fiber and the scintillator-fiber bond has the necessary softness and hardness.

A wavelength shift polymer optical fiber can be manufactured, in accordance with an embodiment of the invention which is now described with reference to the schematic system shown in Figure 6B. The sources of the WSF 606 polymer melt, low refractive index 608 polymer melt, and the 610 phosphor-embedded optically transparent polymer melt, all under pressure, are fed into a co-extrusion die 612 inside from extrusion zone 614, and co-extrude. Dry gas 611, such as dry air or nitrogen, for example, is sprayed onto the extruded fiber for cooling. The polymer melt with a light reflective pigment (such as T1O2, for example) 616 is fed under pressure into an extrusion die 618 for a

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INIílVliTO MEXICANO DE CA EKOPiF.UAD («DUJTSiAL light reflecting jacket on the coated WSF of the esctntliadOI 613. The WSF loaded with the resulting scintillator 620 is wound for storage by means of a winder 622. Figure 6C shows a cross-sectional view of a co-extrusion system, for use in accordance with the embodiments of the present invention, for the manufacture of a scintillator coated WSF. The WSF 606 polymer melt is injected, along with the low refractive index polymer melt 608 and the optically clear phosphor-encrusted polymer melt 610, into a co-extrusion die 612. The polymer melt with light reflecting pigment 616 is fed under pressure into an extrusion die 618. The completed fiber has a WSF core 602, a low index coating 601, a scintillator charged coating 603 and a reflective coating 604.

For all modalities of a scintillation detector according to the present invention, it is advantageous that the thickness of the scintillator material is optimized for the radiation energy to be detected. The design must ensure sufficient light collection to avoid secondary quantum dissipation. In particular, the embodiments of the invention described herein provide detectors of extraordinary lightness with respect to their area.

Definitions: For purposes of the present description, and in any of the appended claims, the term thickness, as applied to the scintillation detector, must represent the mean extension of the

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MEXICAN INSTITUTE OF The FRüi'j EüaD industrial detector in one dimension along, or parallel to, a centroid of the detector's mink field. The term area, as applied to a detector, or, equivalently, the term active area should refer to the size of the detector measured in a plane transverse to the centroid of all radiation propagation vectors within the detector's field of view.

The embodiments of the present invention, even those with up to 8 WSF layers, have ratios of the square of the detector thickness to the active detector area that are less than 0.001. For example, an 8-layer detector with an area of ​​121.92 cm X 30.48 cm, has a thickness not greater than 1.27 cm, so that the ratio of the square of the thickness to the area of ​​the detector is 0.0005. This thickness-square-to-area ratio is usually an order of magnitude or more, less than the comparable ratio for return scattering detectors where the light from the blaster is directly detected by a photo-detector.

According to a further embodiment of the Invention shown in Figure 7, the useful stopping power of the detector can be Increased by combining multiple layers 701, 702 of WSF 400 (or other optical waveguides thus increasing the depth of the material of breaker 403 along the path of Incident radiation.

An embodiment of a wavelength displacement breaker detector in accordance with the present invention is shown in FIG. 8. Wavelength displacement fibers 801 are embedded within the breaker material 803, coupling light and moving toward

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down in frequency for detection by tube-photomultipliers—

805.

In accordance with several of the modalities described so far, the ends of the WSF are grouped together and optically coupled to at least one photo-detector. Examples of suitable photodetectors include PMTs and silicon photomultipliers (SiPMs).

The advantages of the detector, the invention of which is described herein, include detection efficiency and low geometric implementation profile. This allows greater freedom in the design of the detection system and makes new and space-restricted applications fully possible. The mechanical flexibility of the detector structure allows the detector surface to be shaped to conform to the application, such as an implementation where an object represented by an image is surrounded by the volume of the detector. The low profile also makes it relatively easy to orient and protect the detector area in ways to minimize detection of unwanted scattering radiation (interference) from a nearby x-ray imaging system.

Extracting scintillation light over a large region of the scintillator allows detectors a large width to depth aspect ratio. In particular, detectors that subtend spatial angles of 0.1 sr or more are provided by the embodiments of the present invention.

In an x-ray imaging system of

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MEXICAN INSTITUTE OF PROPERTY

INDUSTRIAL

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Typical return scattering, a filiform x-ray beam scans a target represented by an image in linear motion, while elongated radiation detectors are placed on either side of an exit opening of an x-ray source. As the filiform beam moves, the area of ​​the detector closest to the beam will normally receive the strongest signal and the area of ​​the detector away from the beam, the least. If the detector area is segmented into individual reading sections, the detection system's signal-to-noise ratio can be improved by just reading the segments with a good signal-to-noise ratio and leaving the segments that could predominantly contribute noise to the summed signal. Selection to contribute to the detector segments can be made based on the currently detected signal or based on the known position of the filiform beam.

Advantages of extrusion scintillator manufacturing

The automated extrusion or coating process, described above with reference to Figures 6A to 6C, is in complete contrast to typical methods of established polycrystalline scintillation material, such as BaFCI (Eu) on a flat backing. The extrusion method of making the coated individual wave displacement fibers with a uniform scintillator thickness, as taught above, produces fibers that can be profiled so that the constraints on the shape of a Sc-WSF detector are primarily governed at the request of a ί

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complete capture in the fiber by means of a total internal reflection. The concept of uniformly coated coupling fibers gives greater freedom to the design of Return Dispersion Detectors (BX), especially detectors mounted on robots and laptops, where space is valuable.

Deployable detectors to increase the geometric efficiency of scattered x-rays

Some of the mobile x-ray systems, such as those described, for example, in US Patent Nos. 5,764,683 to Swift, et al., And 7,099,434, to Chalmers et al., Both of which are incorporated into the Present by reference, they use the return scattered x-ray (BX) method to inspect cars or trucks from one side. The former uses detectors deployed outside of a transport during operation, so the latter uses a fully contained area of ​​the detector within a confinement, primarily the lining of a transport. Both use large area detectors to maximize efficiency in detecting scattered x-rays. The coverage of the area return dispersion detector in the case of a product in accordance with the teachings of the Chalmers' 434 patent covers the order of 1.84 square meters of the interior surface of a target-oriented confinement. This hidden detector area has a relatively poor geometric efficiency for collecting scattered radiation from low or high targets.

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MEXICAN INSTITUTE OF PROPERTY

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The intrinsically deep geometric profile of these detectors, rieceóáflü "" "for direct capture of scintillation light by means of photomultipliers, is adverse for deployment outside the truck.

Definitions: As used herein, and in any of the appended claims, the term "large area detector" refers to any single detector, or any detector module, that subtends an opening angle of at least 30 ° at each one of the two orthogonal transverse directions as viewed from a point on an object under inspection, equivalently, characterized by a spatial angle of at least π steradians.

A transport can be any device characterized by a platform that originates from the members that make contact with the ground such as wheels, tracks, treads, skates, etc. that are used to transport equipment from one location to another.

A Sc-WSF detector, in accordance with the embodiments of the present invention, makes it practical to discretely store large area detectors that can be quickly deployed outside of the truck in positions that substantially improve detection efficiency.

Referring now to Figure 9, the Sc-WSF large area canopy detector 1101 is shown in a docked position, stored on the roof of a return dispersion inspection van 1103, and a thin skirt detector 1105 shown in a lashing position by

MEXICAN INSTITUTE OF PROPERTY .INDUSTRIAL above a wheel of the return dispersion inspection van. In Figure 10, both the roof and skirt detectors are shown deployed to increase the solid angle to detect higher and lower targets, respectively; the awning detector is deployed above an inspected object during the course of the inspection, while the apron detector is deployed, at least in part, below the transport platform. In another embodiment of the invention, which is described with reference to Figure 11, an awning detector 1301 can be deployed for close and low targets, such as for contraband detection on a truck or on the opposite edge of a car 1303. The awning detector 1301 can be slid off a transport roof prior to the inspection operation. Figure 11 also shows the deployment of the Sc-WSF 1105 skirt detectors used to efficiently examine tires, wheel wells and the interior of closed vehicles.

Dual-energy or multi-energy detectors for scanning transmission of filiform x-ray beams

Filiform x-ray beam scanning not only reveals interior objects by analyzing scattered radiation in return, but in some applications, you can obtain additional information through simultaneous analysis of transmission (TX) and scattered radiation forward (FX) . The TX and FX detectors do not need to be segmented since the area

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I οπ MEXICAN INSTITUTE zy OF PROPERTY

INDUSTRIAL in cross section of the filiform beam, together with the integration time''3e ““ “*” ​​'“^mthe signal defines the pixel size. Also, the TX and FX detectors need only be full power detectors, since in most applications the TX or FX x-ray flux is too high for pulse counting. Scintillation screens are the traditional detectors for such scanning beam applications. Sc-WSF detectors substantially extend the scale of applications of the present TX and FX scintillation detectors, as clarified by the following examples.

TX for x-ray beams up to at least 250 keV

The absorption efficiency of traditional scintillation screens, made for example from BaFCI (Eu) or Gadox, falls below 50% for x-ray energies above ~ 80 keV. The 50% point for two layers is approximately 100 keV. By means of distinction, the Sc-WSF detector can be made with more than two layers of scintillators without substantially increasing the profile of the detector. A cost-effective, 4-layer Sc-WSF detector can be used for TX with scanning x-ray beams generated by a standard 140 keV x-ray tube. A multi-layer detector such as a 9-layer detector, as shown in Figure 12, and generally designated 1400, can be highly effective in detecting 1402 x-rays emitted by a standard 255 keV x-ray tube ( not shown), such as the one '¹ ^ a.'LAWJ of the? ROi'¡ro&gt; G INDUSTRIAL

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used in x-ray inspection of vehicles through show 1404 layers of scintillator material and WSF 1406 fibers that couple to 1408 photodetectors.

Transportable TX detector for top-down imager on three-sided input inspection

The slim profile of the Multilayer Transmission (TX) Detector makes a Transmission Detector (TX) practical at the beginning of the road. Figures 13A and 13B show such a detector within a 5.08 cm 1131 high speed bump strong enough to support a fully loaded tractor trailer, and requiring no digging of the ground for deployment. Penetrating radiation source 1132 emits fan beam 1134 incident on an assembly of linear detector 1135 within frame 1136 of speed reducer 1131 or a similar protrusion above an underlying surface. The detector 1135 assembly includes segments of scintillator material 1137 separated by blades 1138 of a high atomic number. As described above, for example with reference to Figure 4, scintillation light is coupled to the photodetectors by means of wavelength shift optical fibers 1139.

Segmented TX detector to determine the intensity profile of the scanning beam

Referring now to Figures 14A and 14B, a

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MEXICAN INSTITUTE OF THE PROWfDAO

INDUSTRIAL

<img file="MX337476B_D0047.tif" />

Segmented transmission, usually designated 1141, is shown to measure an incident X-ray scan beam intensity profile 1143. An alignment of the Sc-WSF 1141 detector (used for transmission) with the A filiform scanning beam plane presents a significant challenge when the TX detector is deployed for a mobile security system. Figure 14B shows a cross section of a vertical Sc-WSF detector 1141 (otherwise mentioned herein, as appropriate, as a transmission detector or TX detector) with independent reading of the 1145 fibers of the WSFs, which provides the means to simultaneously measure both the transmitted intensity of each pixel and the linear distribution across the beam width to determine its centroid position. Fibers 1145 are routed in groups 1147 to individual photo detectors 1149 such as PMTs. The intensity distribution can be extended outside to obtain the forward scattered intensity, which contains useful information for the scattering material, and gives a measure of the inward scattered radiation that is counted as Transmission intensity.

The relative position of the detector plane and the scanning x-ray plane can be controlled automatically. The detector for this concept is shown schematically in Figure 14A. A reflective surface 1148 can be provided at the end of detector 1141 distal to photodetectors 1149.

With an individual data channel for a transmission signal,

<img file="MX337476B_D0048.tif" />

spatial resolution along the traffic direction (transverse to a fan-shaped illumination x-ray beam) is determined by the smaller of the following two dimensions: the width of the sensitive detector area or the beam size through the TX detector. (For heuristic purposes, the subsampling case is not considered in this description). Spatial resolution can be improved, however, by narrowing the area of ​​the sensitive detector, as now described with reference to Figure 14C. In accordance with the embodiments of the present invention, spatial resolution through the traffic direction (along the detector line) is improved by employing multiple detectors of a detector arrangement 1450 related to a plurality of channels (A , B, C in Figure 14C) and interlacing their sensitive areas. The separation of the interlacing pattern depends on the width of the beam across the detector. Ideally, the gap (i.e. the gap between the two detectors 1451 and 1454 related to a single channel A) should be large enough so that the two detector segments of the same detection channel do not receive direct radiation from to beam at the same time. The beam intensity profile is shown by number 1456. For practical purposes the requirement is not as strict as some amount of interference between pixels is acceptable. Multiple resulting images need to be interlaced, using any method, including methods well known in the art, to create a higher resolution image. . It should be noted that the improvement in spatial resolution in the detector is to

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at the expense of the flow and is thus limited by considerations ae iréñaT * 'to noise.

Another configuration within the scope of the present invention includes a combination of the 1141 vertical detector shown in Figure

14A with a horizontal path detector 1135 of FIG. 13B to form an L-shaped detector that is advantageously easily configured and aligned.

In yet another embodiment of the invention, an arrangement of the transmission detector 1450 (despite the geometric orientation, whether it is vertical, horizontal, L-shaped, etc.) is segmented into a plurality of units; such as B, C, and A of Figure 14C. As shown, the beam profile 1456 is symmetric with respect to B and A so that the ratio of the measured intensities is unity. If, for whatever reason, the alignment changes, the relationship changes dramatically. If the alignment is tilted as a filiform beam of x-rays of illumination is scanned up and down, the change in the B / A ratio measures skewness and lateral shift. The collected data can then be corrected for such displacement on a line-by-line basis.

Multi-energy and dual-energy TX detectors for material identification

Separating the signals from the front and back layers of the scintillators allows the front layer to give a measure of the component of

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nr ta panpiFn. \ n low energy of each pixel while the back layer gives an incelrdarTfrr high energy components. Placing a layer of absorbent material between the front and rear scintillators is a standard way to improve the difference between low-energy and high-energy components, and is easily done with a Sc-WSF detector.

The Sc-WSF detector makes practical a dual energy detector consisting of a Sc-WSF layer, such as BaFCI-WSF on top of a plastic scintillator detector; BaFCI is sensitive to low energy x-rays and not high energy x-rays, while the plastic detector is sensitive to high energy x-rays and very insensitive to low energy x-rays.

A potentially more effective alternative material discriminator can be made by using more than two independent ScWSF layers, with separate readings for each layer. A passive absorber, such as an appropriate thickness of copper, can be inserted after the superior Sc-WSF improves the application of dual energy, as practiced with segmented detectors. Alternatively, the middle scintillator can be used as an active absorption layer. Measurement of the three independent parameters allows one to obtain a measure of both the average atomic number of the cross materials as well as the degree of beam hardening. The Sc-WSF can be extended additionally to obtain more than three energy values ​​for each pixel, the limit is the statistical uncertainties, which increase with the number of components.

<img file="MX337476B_D0051.tif" />

MEXICAN INSTITUTE OF PROPERTY

INDUSTRIAL

<img file="MX337476B_D0052.tif" />

Detector 1400 shown in Figure 12 is an extreme example of such a detector.

An important application of dual energy TX is for x-ray personnel scanners at airport terminals. Providing TX images simultaneously with BX has proven useful for inspection. Adding double power to TX images has so far been impractical primarily due to size restrictions imposed by conventional detectors. The Sc-WSF removes those constraints and promises to significantly improve performance, since multiple detectors, with different energy sensitivities, can be stacked, as shown in Figure 15, where a double (or multiple) 1500 energy detector includes a Sc-WSF 1508 detector, sensitive to lower energy component of incident x-ray 1501, They are placed in a front part of a 1502 plastic scintillator block that is sensitive to the highest energy x-rays. The Sc-WSF 1508 detector contains a 1504 scintillator that is made by two layers of WS 1506 fibers.

Compact gamma radiation and neutron radiation detector

The Sc-WSF method makes an inexpensive, lightweight and small 1601 gamma ray and neutron monitor practical.

BaFCI (Eu) -WSF is very sensitive to gamma radiation while it is insensitive to neutrons, whereas Li⁶F: ZnS (Ag) -WSF is light-insensitive

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MEXICAN INSTITUTE OE THE PROPERTY

INDUSTRIAL

<img file="MX337476B_D0054.tif" />

gamma and very sensitive for the detection of télliliUUü neutrons. shows a multi-layer Dagwood sandwich consisting of one or more 1602 BaFCI (Eu) layers, obtained by a single photo-detector (not shown) using 1604 optical fibers, and one or more 1606 layers of

Li⁶F: ZnS (Ag) -WSF, obtained by a second independent forum-detector (not shown) with the active elements occupying a thickness of not more than one or two centimeters. An appropriate layer of 1612 neutron moderator, such as polyethylene, can be placed on either side of Li⁶F: ZnS (Ag) -WSF to improve the efficiency to detect neutrons. Optically reflective sheet 1608 such as aluminum sheet confines scintillation to the respective regions of the detector.

US Patent Application Serial No. 13 / 163,854 (to Rothschild), which is titled Detector with Active Collimators and is incorporated herein by reference, describes a return dispersion detector module 30 that increases inspection depth by distinguishing dispersion from near and far field of inspected objects, as shown in figure 17. The angle of a set of active collimation vanes 31 can be adjusted either once at the factory or can be fixed to any type of electro-mechanical device provided to dynamically adjust them, depending on the type and / or distance of the object being going to scan. Scintillation light from the collimation vanes is detected by one or more photo-detectors (for example, by PMTs 32 located at the top and bottom of the compartment.

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front of the detector). A rear compartment 36 dtrt detector "secatela" - optically from a front compartment 35 by means of a light deflector 34 and the scintillation light of the x-rays detected in the rear compartment 36 are collected by means of a second set of one more photo-detectors (for example, PMTs 37 mounted on the rear face of the detector. The rear compartment may be aligned with the scintillation phosphor screen, for example, or, in other embodiments of the invention, may contain a liquid or plastic scintillator.

A useful addition to a standard return dispersion unit may be a Venetian blind collimator made from a scintillator. The strips intercept radiation that does not enter directly through the spaces between the strips so that the detectors in the box preferably detect deeper interior objects. Active collimators record the rejected radiation. The light from active collimators is detected by PMTs, whose collection efficiency decreases rapidly as the space between collimators decreases. Replacing PMTs and scintillator blades with blades consisting of Sc-WSF detectors solves the main drawbacks and makes Venetian blind collimators practical. First, the light collection is independent of the width of the space between the blades. Second, the active area of ​​the PMTs or silicon photomultipliers used to collect light from the active collimators is generally much less than the active area of ​​the required PMTs, of / r

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so that the cost of photo-detectors is less. In third place;' Placing the photo-detector at the end of the WSF groups is not critical to the efficiency of light collection. Fourth, the signals from the WSFs from each strip can be processed independently, giving considerable scope to maximize information about the interior of the inspected object. Fifth, the light from the thin scintillator screens at the front and rear of each blade can be collected using Independent WSFs, which can significantly improve depth discrimination.

Figures 18C and 18D show (in perspective and in cross-section, respectively) an active WSF collimator 181 sensitive to x-rays colliding from either side of the scintillator. The scintillation light from both regions of scintillator 182 are coupled to photodetectors by means of wave-shift optical fibers 183. Figures 18A and 18B show (in perspective and in cross-section, respectively) an active WSF collimator 185 with independent readings 187 that are separated by a light-tight x-ray absorber 189 to distinguish the radiation hitting each face. For example, each collimator 185 may consist, in one embodiment, of two layers of the Sc-WSF 182 detectors, each having an area density of 60 mg BaFCkEu per cm2. The light-tight x-ray absorber 189 may consist of a thin layer of tin, which also provides structural support.

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return

The slimness of the Sc-WSF detectors provides unique potential for applications where low weight and power are the drivers. Referring to Figures 19A and 19B, a portable imaging system 193 is an example of such an application. Power requirements, inspection time, and image quality are all affected by the solid angle of detection. A traditional detector with, for example, a cross section of 10 cm x 10 cm (100 cm²), weighs approximately half a kilogram. A 10cm cube of Sc-WSF, which is no more than double the weight, can be made from individual 10cm x 10cm ScWSF detectors, each less than 5mm thick, which can be deployed to present a return dispersion detection area of ​​at least 2,000 cm², a twenty-fold increase in this example. The additional detection coverage can make an order of magnitude improvement in the performance of the portable system.

The slim profile of the Sc-WSF detectors described herein provides profiled detectors with fit in tight spaces. For example, detectors can be adapted for restricted personnel scanners to fit in restricted airport inspection spaces.

Figures 19A and 19B show an example where four detectors 191 fold or slide out of the portable scanner 193

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to substantially increase the efficiency ~ 'Hé' “'3eT6t; Tnórr ^ ·' especially for items hidden deeper in the object to be inspected. Return dispersion detectors 195 position irradiation beam 197 on both sides.

Low-side return dispersion inspection of fixed vehicles

Inspection of the underside of vehicles using a portable x-ray return dispersion system presents special problems. The clear height below the chassis of the cars is not more than 20.32 cm and can be less than 15.24 cm. Fixed inspection systems, such as entrances, can place a detector on the ground or as described above, r can be placed on the ground, using Sc-WSF. However, mobile under-vehicle inspection systems, which are necessary for safety in many areas, have never been developed. Inspectors who rely on passive inspection tools, such as mirrors and cameras, who lose contraband in the gas tank or camouflage themselves to appear harmless.

Sc-WSF detectors make practical an x-ray return scattering system that is no more than 15.24 cm high. An outline of a practical system is now described with reference to Figures 20A and 20B. The x-ray source consists of an electromagnetic scanner 221 of an electron beam through an anode. The electromagnetic scanner

<img file="MX337476B_D0060.tif" />

221 it is powered by the electronic device module 223. The x-rays are collimated by a linear array of apertures 225 spanning, for example

76.2 cm bottom side in one step. Sc-WSF 227 detectors are mounted on each side of the x-ray tube to detect scattered 236 x-rays in return from a 229 vehicle. Power supplies, pulse, and image processors can be properly mounted. Chassis 234 of inspection unit 230 on wheels 232 can be adapted to be maneuvered from underneath a vehicle 229 by means of a motor or manual control.

Mobile transmission inspection with L-shaped detector layout segments

In accordance with another aspect of the present invention, a mobile inspection system, generally designated 240, is now described with reference to Figures 21A and 21B. A penetrating radiation source (not shown, and described herein, without limitation, in terms of x-rays) is transported within a mobile inspection unit 241, which is normally capable of movement under its own power, although it may also be towed or otherwise transported, within the scope of the present invention. A beam 242 of penetrating radiation is emitted from the mobile inspection unit 241, either as a swept threadlike beam or as a fan beam, in any case emitted in the plane designated as the representative beam 242 in FIG. 21A. The

MEXICAN INSTITUTE Dfc THE PROPERTY

INDUSTRIAL

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Inspected object 244, which may be a vehicle as shown, or otherwise (such as a dragged load), crosses beam 242 during the course of the inspection, and, in the course of travel, passes over the detector unit integral L-shaped 245, as now described. Detector unit 245 has a horizontal segment 246 and a vertical segment 247, as indicated in Figure 21B.

Each of the horizontal and vertical segments 246 and 247 of the L-shaped detector unit 245 may be comprised of parallel multiple layers 249 that provide double or more generally multiple x-ray energy resolution detected to provide material identification. , as described above with reference to Figure 12. Additionally, the vertical detector layout segment 247 may have multiple detector segments 248 in a direction transverse to the direction of beam 242 and substantially along the direction of relative movement between inspected object 244 and beam 242 to provide a indication of asymmetry or lateral displacement of the detectors with respect to the beam, as previously described with reference to Figures 14A to 14C. The integral L-shaped detector unit 245 can be transported to an inspection site aboard mobile inspection unit 241 or in a towed trailer or otherwise annex 250 and can be assembled, in part, after deployment to the inspection site. Complementary alignment aids such as alignment laser 251 can be used to establish the proper position and orientation of the

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McXíCANO PROPERTY INSTITUTE

INDUSTRIAL detector unit 245 with respect to mobile inspection unit 241 and eT beam 242.

Where the examples presented herein involve specific combinations of the actions of the methods or elements of the system, it should be understood that those actions and those elements can be combined in other ways to achieve the same objectives of x-ray detection. Additionally, the Individual characteristics of the device can meet the requirements of the separately named elements of a claim. The modalities of the Invention described herein are intended to be merely exemplary; Variations and modifications will be apparent to those skilled in the art. Such variations and modifications are intended to be within the scope of the present invention as defined in any of the appended claims.