X-ray backscatter detector

Abstract

The present invention discloses an x-ray backscatter detector, and specifically discloses a scintillator used in an x-ray backscatter system. The scintillator includes an inorganic scintillator portion, which is made of an inorganic scintillating material and includes one or more inorganic material elements. Each inorganic material element in the one or more inorganic material elements includes an outer surface and an inner surface opposite to the outer surface. The outer surface is configured to be close to an object to be scanned so that the outer surface is configured to receive x-ray photons scattered by the object. The scintillator also includes an organic scintillator portion, which is made of an organic scintillating material and includes a front surface. At least a portion of the front surface is adjacent to the inner surface of at least one inorganic material element in the one or more inorganic material elements.

Description

Technical Field

[0001] The present disclosure relates generally to detection of scattered x-rays in an x-ray backscatter system, and more particularly to detection of scattered x-rays using a scintillator including an inorganic scintillating material and an organic scintillating material. Background Art

[0002] X-ray backscatter systems can be used to perform non-destructive inspection of objects (subjects), including detecting non-line-of-site features of the object. A conventional x-ray backscatter system includes an x-ray tube and a detector. The detector includes a photomultiplier tube (PMT) and a scintillator. The x-ray tube emits x-rays toward the object. When the x-rays collide with components of the object, the x-rays are diffracted, and some of the x-ray photons travel toward the detector. When the x-ray photons hit the outer surface of the scintillator, some of the x-rays are reflected from the outer surface, while some of the x-rays penetrate the outer surface. Of the x-rays that penetrate the outer surface, some of the x-rays hit the back surface of the scintillator and are reflected back inside the scintillator, while other x-rays penetrate the back surface and leave the scintillator.

[0003] The PMT detects the photoemission that occurs when electrons of atoms of the scintillator absorb energy from x-rays, exciting the electrons to a higher energy state (the electrons then fall back to their original state, causing photoemission). The PMT can detect the amount of photoemission within the scintillator. Alternatively, the PMT can detect the brightness of the total effect of the photoemission within the scintillator.

[0004] Some deficiencies of conventional x-ray backscatter systems involve the inability to absorb energy from x-rays traveling toward the detector. For example, when x-rays reflect off the outer surface of the scintillator or penetrate the back surface and exit the scintillator, the opportunity to absorb energy from x-rays is lost. These deficiencies may be caused by excessive distribution of energies of the various x-rays diffracted from the components of the object. For example, a scintillator calibrated for x-rays with a median expected energy (e.g., by a selected thickness of the material) may result in relatively low-energy x-rays reflecting off the outer surface and / or relatively high-energy x-rays penetrating through the back surface.

[0005] To compensate for some of these deficiencies, some x-ray backscatter systems use relatively high x-ray power supplies to generate a sufficient amount of x-rays for which the scintillator is calibrated. In this way, even though the scintillator may not absorb energy from low-energy and high-energy x-rays, the scintillator can still detect enough x-rays to provide information for imaging an object. However, these high-power x-ray backscatter systems are expensive to produce and operate, and have poor portability.

[0006] Therefore, a need exists for an x-ray backscatter system having a scintillator configured to absorb energy from x-rays having a relatively wide energy range. Summary of the invention

[0007] The subject matter of the present application provides exemplary scintillators that overcome the above-mentioned shortcomings of the prior art, x-ray backscatter systems that implement such scintillators, methods of using scintillators, and methods of manufacturing scintillators. The subject matter of the present application was developed in response to the prior art, and in particular in response to the shortcomings of conventional scintillators and conventional methods and systems for producing scintillators and operating x-ray backscatter systems to detect x-rays.

[0008] A scintillator is disclosed herein, which includes an inorganic scintillator portion made of an inorganic scintillator material and an organic scintillator portion made of an organic scintillator material. The inorganic scintillator portion includes one or more inorganic material elements. Each of the inorganic material elements includes an outer surface and an inner surface opposite to the outer surface. The outer surface is configured to be close to an object (subject) to be scanned with an x-ray backscatter system, so that the outer surface is configured to receive x-ray photons scattered by the object. The organic scintillator portion includes a front surface, wherein at least a portion of the front surface is adjacent to the inner surface of at least one of the one or more inorganic material elements. The foregoing subject of this paragraph characterizes Example 1 of the present disclosure.

[0009] The inorganic scintillator portion further includes a plurality of inorganic material elements spaced apart from each other. The plurality of inorganic material elements are disposed on correspondingly spaced apart first portions of the front surface of the organic scintillator portion. The second portion of the front surface of the organic scintillator portion is free of inorganic material elements. The foregoing subject matter of this paragraph characterizes Example 2 of the present disclosure, wherein Example 2 also includes subject matter according to Example 1 above.

[0010] A plurality of spaced-apart first sections of the front surface of the organic scintillator portion are recessed relative to a second section of the front surface of the organic scintillator portion that is free of inorganic scintillating material. The foregoing subject matter of this paragraph characterizes Example 3 of the present disclosure, wherein Example 3 also includes subject matter according to Example 2 above.

[0011] The inorganic scintillator portion includes an inorganic material element disposed on substantially all of the front surface of the organic scintillator portion.The foregoing subject matter of this paragraph characterizes Example 4 of the present disclosure, wherein Example 4 also includes subject matter according to Example 1 above.

[0012] The inorganic scintillating material has an index of refraction different from an index of refraction of the organic scintillating material.The foregoing subject matter of this paragraph characterizes Example 5 of the present disclosure, wherein Example 5 also includes subject matter according to any one of Examples 1 to 4 above.

[0013] The scintillator further includes a second inorganic scintillator portion made of a second inorganic scintillator material. The organic scintillator portion further includes a rear surface opposite to the front surface. The second inorganic scintillator portion is disposed on the rear surface of the organic scintillator portion. The aforementioned subject matter of this paragraph characterizes Example 6 of the present disclosure, wherein Example 6 also includes subject matter according to any one of Examples 1 to 5 above.

[0014] The inorganic scintillating material and the second inorganic scintillating material are the same.The foregoing subject matter of this paragraph characterizes Example 7 of the present disclosure, wherein Example 7 also includes subject matter according to Example 6 above.

[0015] The scintillator includes a third inorganic scintillator portion made of a third inorganic scintillator material. The organic scintillator portion further includes one or more side surfaces extending between the front surface and the rear surface. The third inorganic scintillator portion is disposed on one or more side surfaces of the organic scintillator portion. The aforementioned subject matter of this paragraph characterizes Example 8 of the present disclosure, wherein Example 8 also includes subject matter according to any one of Examples 6 to 7 above.

[0016] The organic scintillating material includes one or more of plastic and polyurethane.The foregoing subject matter of this paragraph characterizes Example 9 of the present disclosure, wherein Example 9 also includes subject matter according to any one of Examples 1 to 8 above.

[0017] The inorganic scintillating material includes one or more of lead iodide (PbI2), calcium tungstate (CaWO4), and cesium iodide (CsI). The foregoing subject matter of this paragraph characterizes Example 10 of the present disclosure, wherein Example 10 also includes subject matter according to any one of Examples 1 to 9 above.

[0018] Each of the one or more inorganic material elements has a thickness defined between an outer surface and an inner surface. The thickness corresponds to the energy of the x-rays emitted by the x-ray backscatter system. The aforementioned subject matter of this paragraph characterizes Example 11 of the present disclosure, wherein Example 11 also includes subject matter according to any one of Examples 1 to 10 above.

[0019] The organic scintillator portion further includes a rear surface opposite to the front surface. The organic scintillator portion is configured with a thickness defined between the front surface and the rear surface. The thickness corresponds to the energy of the x-rays used in the x-ray backscatter system. The foregoing subject matter of this paragraph characterizes Example 12 of the present disclosure, wherein Example 12 also includes subject matter according to any one of Examples 1 to 11 above.

[0020] The organic scintillator portion couples the inorganic scintillator portion 112 with the photomultiplier tube.The foregoing subject matter of this paragraph characterizes Example 13 of the present disclosure, wherein Example 13 also includes subject matter according to any one of Examples 1 to 12 above.

[0021] In addition, a method for producing a scintillator is disclosed herein. The method includes: disposing an organic scintillating material layer on a substrate. The organic scintillating material layer includes a front surface and a rear surface adjacent to the substrate. The organic scintillating material layer defines a plurality of voids at the front surface. The method also includes disposing one or more inorganic material elements in one or more voids of the plurality of voids. The foregoing subject matter of this paragraph characterizes Example 14 of the present disclosure.

[0022] Providing an organic scintillating material layer on the substrate includes: removing a certain amount of organic scintillating material at multiple locations on the front surface. The removed amount of organic scintillating material defines multiple gaps at the front surface. The aforementioned subject matter of this paragraph characterizes Example 15 of the present disclosure, wherein Example 15 also includes subject matter according to Example 14 above.

[0023] The plurality of voids have a thickness between 1 micrometer and 100 micrometers.The foregoing subject matter of this paragraph characterizes Example 16 of the present disclosure, wherein Example 16 also includes subject matter according to any of Examples 14 and 15 above.

[0024] The organic scintillating material layer has a thickness defined between the front surface and the rear surface. The thickness of the organic scintillating material layer is between 0.5 inches and 10 inches. The foregoing subject matter of this paragraph characterizes Example 17 of the present disclosure, wherein Example 17 also includes subject matter according to any one of Examples 14 to 16 above.

[0025] The present invention further discloses a method for operating an x-ray backscatter system. The method includes: sending x-rays toward an object via an x-ray tube of the x-ray backscatter system. The method also includes: detecting one or more x-ray photons scattered by the object via a scintillator of the x-ray backscatter system. The scintillator includes: an inorganic scintillator portion made of an inorganic scintillating material, and an organic scintillator portion made of an organic scintillating material. The inorganic scintillating material includes one or more inorganic material elements. Each of the one or more inorganic material elements includes an inner surface close to the outer surface of the object and opposite to the outer surface. The organic scintillator portion includes a front surface, wherein at least a portion of the front surface is adjacent to the inner surface of at least one of the one or more inorganic material elements. The foregoing subject matter of this paragraph characterizes Example 18 of the present disclosure.

[0026] Detecting one or more x-ray photons scattered by the object includes: receiving at least one of the one or more x-ray photons via an inorganic scintillator portion. Detecting one or more x-ray photons scattered by the object also includes: generating photoelectric emission in the scintillator in response to receiving at least one of the one or more x-ray photons. Detecting one or more x-ray photons scattered by the object further includes detecting the photoelectric emission via a photomultiplier tube of an x-ray backscatter system. The foregoing subject matter of this paragraph characterizes Example 19 of the present disclosure, wherein Example 19 also includes subject matter according to Example 18 above.

[0027] The method further includes: based on transmitting and detecting, providing information that can be used to generate an x-ray image of the object to an imaging device. The foregoing subject matter of this paragraph characterizes Example 20 of the present disclosure, wherein Example 20 also includes subject matter according to any one of Examples 18 to 19 above.

[0028] The described features, structures, advantages and / or characteristics of the subject matter of the present disclosure can be combined in any suitable manner in one or more examples including embodiments and / or implementations. In the following description, many specific details are provided to give a thorough understanding of the examples of the subject matter of the present disclosure. Those skilled in the relevant art will recognize that the subject matter of the present disclosure can be practiced in the absence of one or more of the specific features, details, parts, materials and / or methods of a particular example, embodiment or implementation. In other cases, additional features and advantages that are not present in all examples, embodiments or implementations may be recognized in certain examples, embodiments and / or implementations. In addition, in some instances, well-known structures, materials or operations are not shown or described in detail to avoid blurring the aspects of the subject matter of the present disclosure. The features and advantages of the subject matter of the present disclosure will become more completely apparent according to the following description and the appended claims, or can be known by the practice of the subject matter set forth below. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order that the advantages of the subject matter may be more readily understood, a more particular description of the subject matter briefly described above will be provided by reference to specific examples illustrated in the accompanying drawings. It will be understood that these drawings depict only typical examples of the subject matter and therefore they should not be considered limiting of the scope of the invention. Through the use of the accompanying drawings, the subject matter will be described and explained with additional specificity and detail, in which:

[0030] Figure 1 is a schematic perspective view of an x-ray backscatter system for inspecting a part according to one or more examples of the present disclosure;

[0031] Figure 2a to Figure 2h yes Figure 1 Side views of various examples of scintillators for x-ray backscatter systems;

[0032] Figure 3a to Figure 3d yes Figure 1 A top view of various examples of scintillators for an x-ray backscatter system;

[0033] Figure 4 is a schematic flow chart of a process of manufacturing a scintillator shown from a side view of the scintillator according to one or more examples of the present disclosure;

[0034] Figure 5 is a flow chart of a method of manufacturing a scintillator according to one or more examples of the present disclosure; and

[0035] Figure 6 is a flow chart of a method of operating an x-ray backscatter system according to one or more examples of the present disclosure. DETAILED DESCRIPTION

[0036] Throughout this specification, references to "one example," "example," or similar language mean that a specific feature, structure, or characteristic described in conjunction with the example is included in at least one example of the present disclosure. Throughout this specification, appearances of the phrases "in one example," "in an example," and similar language may, but need not, all refer to the same example. Similarly, use of the term "implementation" means an implementation having a specific feature, structure, or characteristic described in conjunction with one or more examples of the present disclosure, however, an implementation may be associated with one or more examples if no explicit correlation is indicated.

[0037] Disclosed herein are scintillators each having an organic scintillator portion and an inorganic scintillator portion. The inorganic scintillator portion includes an inorganic scintillator material disposed on all or a portion of the front surface of the organic scintillator portion. In addition, in some examples, the inorganic scintillator portion is also disposed on the rear surface and / or side surface of the organic scintillator portion.

[0038] The inorganic scintillating material may be embedded into the front surface of the organic scintillating material. For example, the process of manufacturing the scintillator may include disposing an organic scintillating material layer on a substrate, wherein the organic scintillating material layer defines a plurality of voids at its front surface. The process then includes arranging one or more inorganic material elements within the plurality of voids, thereby embedding the inorganic material elements into the front surface of the organic scintillating material layer.

[0039] When compared to a conventional x-ray backscatter system operating with the same power supply, an x-ray backscatter system having one or more scintillators as described herein can detect an increased amount of photoemission based on the absorption of additional energy from scattered x-rays having relatively high and / or relatively low energy. This can be used to produce x-ray images with improved resolution. In addition, when compared to a conventional x-ray backscatter system producing x-ray images with similar resolution, the x-ray backscatter system described herein can consume less power, have a lower manufacturing cost, and / or have better portability based on system size and weight.

[0040] Reference Figure 1 According to some examples, a nondestructive inspection system 100 is disclosed herein, wherein an x-ray backscatter system 102 may be implemented according to one or more examples of the present disclosure. The x-ray backscatter system 102 includes an x-ray source, such as an x-ray tube 104. The x-ray tube 104 may include an x-ray emitter 106 and an aperture 108 through which the emitted x-rays may exit the x-ray tube 104 toward an object for scanning.

[0041] The x-ray backscatter system 102 also includes one or more scintillators 110. The one or more scintillators 110 include an inorganic scintillator portion 112 made of an inorganic scintillating material, such as one or more of lead iodide (PbI2), calcium tungstate (CaWO4), and cesium iodide (CsI). The one or more scintillators 110 also include an organic scintillator portion 114 made of an organic scintillating material, such as plastic, polyurethane, or other carbon-based materials.

[0042] In some embodiments, the inorganic scintillating material has a refractive index that is different from the refractive index of the organic scintillating material. This may cause the x-ray photon 122 to change its vector when striking the interface between the inorganic scintillator portion 112 and the organic scintillator portion 114. For example, one or more x-ray photons 122 may be reflected back within the inorganic scintillator portion 112. Additionally or alternatively, one or more x-ray photons 122 may penetrate the organic scintillator portion 114 and may change their trajectory upon penetration. The change in vector may cause the scintillator 110 to absorb energy from the x-ray photon 122 and cause photoemission to be detected by the PMT 116, as described below.

[0043] The x-ray backscatter system 102 also includes a photomultiplier tube (PMT) 116 coupled to the scintillator 110. For example, the PMT 116 may be coupled to an organic scintillator portion 114 that couples the inorganic scintillator portion 112 with the PMT 116. The scintillator 110 and the PMT 116 may be collectively defined as a detector.

[0044] In an example operation of the x-ray backscatter system 102, the x-ray emitter 106 draws power from a power source to emit x-rays 118 through the aperture 108 toward an object 120. The object 120 is a part (e.g., component, device, assembly, etc.) before or after use. In addition, the object 120 may be removed from a larger assembly for inspection, or the object 120 may be inspected in situ on or in a larger assembly. When the x-rays 118 collide with components of the object 120, the x-rays 118 are diffracted to cause some of the diffracted x-ray photons 122 to travel toward one or more scintillators 110.

[0045] When the diffracted x-ray photons 122 strike the outer surface of the scintillator 110, at least some of the diffracted x-ray photons 122 enter the inorganic scintillator portion 112 before striking the organic scintillator portion 114. A group of the diffracted x-ray photons 122 that enter the inorganic scintillator material 112 transfer energy to particles of one or both of the organic scintillator portion 114 and the inorganic scintillator portion 112, which in turn release photoemissions that are detected by the PMT 116. This process can be described as the scintillator 110 absorbing energy from the diffracted x-ray photons 122. Because the scintillator 110 includes the inorganic scintillator portion 112 and the organic scintillator portion 114, the scintillator 110 is more likely to absorb energy from diffracted x-ray photons 122 having relatively high energy and / or relatively low energy.

[0046] The PMT 116 may then provide information to an imaging device 124 of the nondestructive inspection system 100 based on the detection of the photoemissions. The imaging device 124 may be used to generate an x-ray image 126 of the object 120. The information may include a count of the detected photoemissions, or an indication of the brightness based on the detection of the photoemissions. The count or brightness may also be associated with the location of the object 120. For example, the count or brightness may be associated with the location to which the x-rays 118 of the object 120 are directed. The information may further include a plurality of counts or brightnesses, each of which is associated with a respective one of a plurality of locations to which the x-rays 118 of the object 120 are directed. The association may be determined based on the time at which the PMT 116 detects the photoemissions and an indication of the location to which the x-rays 118 of the object 120 are directed at the detected time.

[0047] Figure 2a to Figure 2h A side view of an example of a scintillator similar to scintillator 110 is shown, where like reference numerals refer to like elements. Figure 2a to Figure 2h The various scintillators shown help illustrate some of the various examples of the inorganic scintillator portion 112 and the organic scintillator portion 114 .

[0048] Reference Figure 2aAccording to one example, the inorganic scintillator portion 112 of the scintillator 110a includes an inorganic material element 202. The inorganic material element 202 includes an outer surface 204 and an inner surface 206, the inner surface 206 being opposite to the outer surface 204. The outer surface 204 is configured to be close to an object 120 to be scanned using the x-ray backscatter system 102, so that the outer surface 204 is configured to receive x-ray photons 122 scattered by the object 120. The inorganic material element 202 has a thickness T1 defined between the outer surface 204 and the inner surface 206. The thickness T1 can be selected to correspond to the energy of the x-ray to be emitted by the x-ray backscatter system 102. In some embodiments, the thickness T1 is between 1 micron and 100 microns. In particular, the thickness T1 can be approximately 10 microns.

[0049] The organic scintillator portion 114 of the scintillator 110a includes a front surface 208 and a rear surface 210, the rear surface 210 being opposite the front surface 208. At least a portion of the front surface 208 abuts the inner surface 206 of the inorganic material element 202. The organic scintillator portion 114 has a thickness T2 defined between the front surface 208 and the rear surface 210. The thickness T2 can be selected to correspond to the energy of the x-rays 118 to be emitted by the x-ray backscatter system 102. In some embodiments, the thickness T2 is between 0.5 inches and 100 inches. In particular, the thickness T1 can be approximately 1 inch.

[0050] Reference Figure 2b Another example of the scintillator 110 b includes a plurality of inorganic scintillator portions provided on a plurality of surfaces of the organic scintillator portion 114 .

[0051] In addition to the inorganic scintillator portion 202 disposed on the front surface 208 of the organic scintillator portion 114, the scintillator 110b may further include a second inorganic scintillator portion 212 made of a second inorganic scintillating material disposed on the rear surface 210 of the organic scintillator portion 114. Additionally or alternatively, the scintillator 110b may include a third inorganic scintillator portion 214 made of a third inorganic scintillating material disposed on one or more side surfaces 216 of the organic scintillator portion 114. The side surface 216 may include any or all surfaces extending between the front surface 208 and the rear surface 210.

[0052] The first inorganic scintillating material and the second inorganic scintillating material may be the same. Additionally or alternatively, the first inorganic scintillating material and the third inorganic scintillating material may be the same, the second inorganic scintillating material and the third inorganic scintillating material may be the same, or each of the scintillating materials may be the same. In other embodiments, each of the inorganic scintillating materials may be different.

[0053] exist Figure 2a and Figure 2bIn the first example of the scintillator 110a and the second example of the scintillator 110b shown in FIG, the inorganic scintillator portion 112 includes an inorganic material element 202 disposed on substantially all of the front surface of the front surface 208 of the organic scintillator portion 114. However, in the embodiments discussed below, the inorganic scintillator portion 112 includes a plurality of inorganic material elements 202, and only a portion of the front surface 208 is adjacent to the inner surfaces 206 of the plurality of inorganic material elements 202.

[0054] Reference Figure 2c to Figure 2h , the inorganic scintillator portion 112 of the scintillator 110b to the scintillator 110h includes a plurality of inorganic material elements 202. Each of the inorganic material elements 202 includes: an outer surface 204 configured to be close to the object 120, and an inner surface 206 opposite to the outer surface. As shown in the figure, each of the inorganic material elements 202 is spaced apart from each other. The inorganic material elements 202 have respective diameters (D), which may be common to all or some of the inorganic material elements 202.

[0055] The front surface 208 of the organic scintillator portion 114 includes one or more spaced-apart first portions 218 and one or more second portions 220, which may be connected or spaced apart. The inorganic material elements 202 are disposed on the corresponding spaced-apart first portions 218 of the front surface 208 of the organic scintillator portion 114. The second portions 220 of the front surface 208 of the organic scintillator portion 114 are free of the inorganic material elements 202.

[0056] Reference Figure 2c According to another example, the scintillator 110c includes a plurality of inorganic scintillator elements 202 embedded in the organic scintillator portion 114. One or more spaced-apart first portions 218 of the front surface 208 are recessed relative to one or more second portions 220 of the front surface 208. In other words, a thickness T2 between the rear surface and the one or more second portions 220 is greater than a thickness between the rear surface and the one or more spaced-apart first portions 218. In addition, an outer surface 204 of the one or more inorganic scintillator elements 202 may be substantially coplanar with the one or more second portions 220 of the front surface 208. In some alternative examples, as shown by the dashed lines, an additional set of inorganic scintillator elements 202 are embedded in the rear surface 210 of the organic scintillator portion 114.

[0057] The inorganic scintillator elements 202 of the scintillator 110 c may be, for example, pillar-shaped or rectangular prism-shaped.

[0058] Reference Figure 2dAccording to another example, the scintillator 110d includes a plurality of inorganic scintillator elements 202 disposed on a generally planar portion of a front surface 208. One or more spaced-apart first portions 218 of the front surface 208 are generally coplanar with one or more second portions 220 of the front surface 208 between the one or more spaced-apart first portions.

[0059] Reference Figure 2e According to yet another example, the scintillator 110e includes a plurality of inorganic scintillator elements 202 partially embedded in the organic scintillator portion 114. One or more spaced-apart first portions 218 of the front surface 208 are recessed relative to one or more second portions 220 of the front surface 208. However, in contrast to the scintillator 110c, the outer surface 204 of the inorganic scintillator element 202 extends outward relative to the one or more second portions 220 (i.e., the one or more second portions 220 are recessed relative to the outer surface 204).

[0060] Reference Figure 2f According to a further example, the scintillator 110f includes a plurality of inorganic scintillator elements 202 embedded in an organic scintillator portion 114. Individual ones of the inorganic scintillator elements 202 have a diameter D that decreases from an outer surface 204 to an inner surface 206. In other words, the inorganic scintillator elements 202 have angled side surfaces that are not orthogonal to one or both of the outer surface 204 and the inner surface 206. These angled side surfaces can increase the likelihood that an x-ray photon 122 passing through the inorganic scintillator element 202 strikes the organic scintillator portion 114 at a surface that is not orthogonal to the path of the x-ray photon 122. This can increase the likelihood that the x-ray photon 122 travels a longer distance through the scintillator 114, and likewise increase the likelihood that the scintillator 110 absorbs energy from the x-ray photon 122 and produces detectable photoemission.

[0061] The inorganic scintillator elements 202 of the scintillator 110f may be, for example, frustoconical or trapezoidal prisms.

[0062] Reference Figure 2g In another example, the scintillator 110g includes a plurality of inorganic scintillator elements 202 embedded in the organic scintillator portion 114. Similar to the inorganic scintillator elements 202 of the scintillator 110f, each of the inorganic scintillator elements 202 in the scintillator 110g has a diameter D that decreases from an outer surface 204 to an inner surface 206. However, in contrast, the inner surface 206 of the scintillator 110g is an edge or point rather than a surface that is generally parallel to the outer surface 204.

[0063] The inorganic scintillator elements 202 of the scintillator 110g may be, for example, pyramidal or triangular prisms.

[0064] Reference Figure 2h According to another example, the scintillator 110h includes a plurality of inorganic scintillator elements 202 partially embedded in the organic scintillator portion 114. Similar to the inorganic scintillator elements 202 of the scintillator 110f, each of the inorganic scintillator elements 202 in the scintillator 110g has a diameter D that decreases from the outer surface 204 to the inner surface 206. However, in contrast, the inorganic scintillator element 202 includes a portion having a substantially uniform diameter. The portion having a substantially uniform diameter may be: a portion of the inorganic scintillator element 202 that is not embedded in the organic scintillator portion 114 (i.e., a portion outwardly of the second portion 220 relative to the front surface 208 of the organic scintillator portion 114).

[0065] Figure 3a to Figure 3d A top view of non-limiting examples of various scintillators 110i-110l that may be scintillators of the x-ray backscatter system 102 is shown. Aspects of one or more of scintillators 110i-110l may be combined with aspects of one or more of scintillators 110a-110h.

[0066] Reference Figure 3a According to another example, the scintillator 110i includes an inorganic material element 202 having an outer surface 204 disposed on a front surface 208 (at the front of the organic scintillator portion 114) Figure 2a to Figure 2h The outer surface 204 of the inorganic material element 202 has a diameter D and a width W1.

[0067] Reference Figure 3b According to another example, the scintillator 110j includes an inorganic material element 202 having an outer surface 204 disposed on a front surface 208 (at the front of the organic scintillator portion 114) Figure 2a to Figure 2h As in the scintillator 110i, the outer surface 204 of the inorganic material element 202 has a diameter D and a width W1.

[0068] In addition to the front surface 208 (such as Figure 2a to Figure 2h In addition to the inorganic scintillator portion 202 on the front surface 208 and the rear surface 210, the scintillator 110j includes a third inorganic scintillator portion 214 made of a third inorganic scintillating material and disposed on one or more side surfaces 216 of the organic scintillator portion 114. The side surface 216 may include any or all surfaces extending between the front surface 208 and the rear surface 210.

[0069] Reference Figure 3cAccording to another example, the scintillator 110k includes a plurality of inorganic material elements 202 having an outer surface 204 disposed on a first portion 218 ( Figures 2a to 2h The second portion 220 of the front surface 208 is free of the inorganic material element 202.

[0070] The inorganic material element 202 has a diameter D and a width W1, which may be the same for all inorganic material elements 202. Alternatively, one or more of the diameter D and the width W1 may be different for respective ones or groups of inorganic material elements in the inorganic material element 202. The organic scintillator portion 114 has a width W2, which may be greater than the width W1 of the inorganic material element 202.

[0071] The inorganic material element 202 of the scintillator 110 k may be, for example, columnar or pyramidal. Additionally or alternatively, the inorganic material element 202 may be embedded or partially embedded in the organic scintillator portion 114 .

[0072] The inorganic material elements 202 may be distributed uniformly, randomly, or at different predetermined densities across the front surface 208 of the organic scintillator portion 114. For example, the inorganic material elements 202 may be distributed at a relatively high density at a location of the scintillator 110k closest to the x-ray source, and at a relatively low density at a location of the scintillator 110k farthest from the x-ray source.

[0073] Reference Figure 3d According to another example, the scintillator 1101 includes a plurality of inorganic material elements 202 having an outer surface 204 disposed on a first portion 218 ( Figures 2a to 2h The second portion 220 of the front surface 208 is free of the inorganic material element 202.

[0074] Similar to the inorganic material elements 202 of the scintillator 110k, the inorganic material elements 202 of the scintillator 110l have a diameter D and a width W1, which may be the same for all inorganic material elements 202. Alternatively, one or more of the diameter D and the width W1 may be different for respective ones or groups of inorganic material elements in the inorganic material elements 202. The organic scintillator portion 114 has a width W2, which may be greater than the width W1 of the inorganic material elements 202.

[0075] The inorganic material elements 202 of the scintillator 110k can be, for example, rectangular or trapezoidal prisms. Additionally or alternatively, the inorganic material elements 202 can be embedded or partially embedded in the organic scintillator portion 114. Furthermore, the inorganic material elements 202 can be distributed across the front surface 208 of the organic scintillator portion 114 uniformly, randomly, or at different predetermined densities.

[0076] Now refer to Figure 4 , according to some examples, a process 400 for producing a scintillator 110 is illustrated. The process 400 can be used to produce any one or more of the examples of the scintillator 110 disclosed herein. The process 400 optionally includes providing an organic scintillating material layer 402 on a substrate 404. The layer 402 has a thickness (T2) defined between a front surface 406 and a rear surface 408, which is generally uniform. In some implementations, the thickness T2 of the organic scintillating material layer 402 is between 0.5 inches and 10 inches. In particular, the thickness T2 can be about 1 inch.

[0077] Then, process 400 includes forming a plurality of voids 410 within a front surface 406 of an organic scintillating material layer 402. To form the plurality of voids, some of the organic scintillating material may be removed (e.g., via etching) from a plurality of sections of the front surface 406 of the layer 402. Alternatively, additional organic scintillating material may be disposed at a plurality of portions of the front surface 406 of the layer 402 such that voids are created in the remainder of the front surface 406 of the layer 402. The voids 410 have a thickness T3 that is less than a thickness T2 of the organic scintillating material layer 402. In some implementations, each of the voids 410 has substantially the same thickness T3, while in other implementations, the voids have different thicknesses T3. The voids 410 may have a thickness between 1 micrometer and 100 micrometers. More particularly, the voids 410 may have a thickness of approximately 10 micrometers.

[0078] The process 400 includes disposing one or more inorganic material elements 412 having a thickness T1 within one or more voids in the plurality of voids 412. In some implementations, this step includes disposing an inorganic scintillating material layer on the entire front surface 406 of an organic scintillating material layer 402, and then removing a portion of the inorganic scintillating material to leave the spaced-apart inorganic material elements 412 embedded in the organic scintillating material layer 402.

[0079] Figure 5A method 500 for producing a scintillator 110 according to certain examples is shown. The method 500 is performed in any one or more of the examples of producing the scintillator 110 disclosed herein. The method 500 includes (block 502) disposing an organic scintillating material layer 402 on a substrate 404, the layer 402 defining a plurality of voids 410 at a front surface 406 of the layer 402. In some implementations, the organic scintillating material layer 402 includes a rear surface 210, 408 adjacent to the substrate 404 and a front surface 208, 406. The operation (block 502) optionally includes: (block 502a) removing an amount of the organic scintillating material at a plurality of locations of the front surface 208, 406 to provide the plurality of voids 410.

[0080] The method 500 further includes (block 504 ) disposing one or more inorganic scintillator elements 202 , 412 within one or more voids in the plurality of voids 410 .

[0081] Figure 6 A method 600 of operation of an x-ray backscatter system 102 according to certain examples is shown. The method 600 is performed using any one or more of the examples of the scintillator 110 disclosed herein. The method 600 includes (block 602) transmitting an x-ray 118 toward an object 120. For example, the method may include transmitting the x-ray 118 toward the object 120 via an x-ray tube 104 of the x-ray backscatter system 102.

[0082] The method also includes (block 604) detecting, via the scintillator 110 of the x-ray backscatter system 102, one or more x-ray photons 122 scattered by the object 120. The scintillator 110 can be any of the scintillators 110 disclosed herein. For example, the scintillator 110 includes an inorganic scintillator portion 112 made of an inorganic scintillating material and including one or more inorganic material elements 202. Each of the one or more inorganic material elements 202 includes an inner surface 206 proximate to and opposite to an outer surface 204 of the object 120. The scintillator 110 also includes an organic scintillator portion 114 made of an organic scintillating material and including a front surface 208. At least a portion of the front surface 208 is adjacent to the inner surface 206 of at least one of the one or more inorganic material elements 202.

[0083] (Block 604) The detecting may optionally include (Block 604a) receiving at least one of the one or more x-ray photons 122 via the inorganic scintillator portion 112. (Block 604) The detecting may also include generating (604b) photoemission within the scintillator 110 in response to (Block 604) receiving at least one of the one or more x-ray photons 122. (Block 604) The detecting may further include (604c) detecting the photoemission via a photomultiplier tube 116 of the x-ray backscatter system 102.

[0084] The method optionally includes (block 606 ) providing information that can be used to generate an x-ray image ( 126 ) of the object 120 to the imaging device 124 based on the transmitting (block 602 ) and the detecting (block 604 ).

[0085] In the above description, certain terms may be used, such as "upper", "lower", "upper", "lower", "horizontal", "vertical", "left", "right", "above", "below", etc. These terms are used when applicable to provide some clear description when dealing with relative relationships. However, these terms are not intended to imply absolute relationships, positions and / or orientations. For example, with respect to an object, the "upper" surface can become the "lower" surface simply by turning the object over. Nevertheless, it is still the same object. In addition, unless otherwise expressly stated, the terms "include", "comprise", "have" and their variations mean "including but not limited to". Unless otherwise expressly stated, the list of items listed does not imply that any or all of the items in the items are mutually exclusive and / or mutually inclusive. Unless otherwise expressly stated, the terms "one", "an" and "the" also refer to "one or more". In addition, the term "multiple" can be defined as "at least two".

[0086] In addition, examples of an element "connected" to another element in this specification may include direct and indirect connections. Direct connection may be defined as an element connected to another element and forming a certain contact with the other element. Indirect connection may be defined as a connection between two elements that are not in direct contact with each other, but have one or more additional elements between the connected elements. In addition, as used herein, fixing an element to another element may include direct fixing and indirect fixing. In addition, as used herein, "adjacent" does not necessarily mean contact. For example, an element may be adjacent to another element without contacting the element.

[0087] As used herein, the phrase "at least one" when used with a list of items means that different combinations of one or more of the listed items can be used, and only one of the items in the list may be needed. The item can be a specific object, thing, or category. In other words, "at least one" means that any combination of items or the number of items can be used from the list, but not all items in the list may be needed. For example, "at least one of item A, item B, and item C" may mean item A; item A and item B; item B; item A, item B, and item C; or item B and item C. In some cases, "at least one of item A, item B, and item C" may mean (for example, but not limited to) two of item A, one of item B, and ten of item C; four of item B and seven of item C; or other suitable combinations.

[0088] Unless otherwise indicated, the terms "first", "second", etc. are used herein merely as labels and are not intended to impose order, position, or hierarchy requirements on the items to which these terms refer. Furthermore, reference to an item, such as a "second", does not require or preclude the existence of an item, such as a "first" or lower numbered item and / or an item, such as a "third" or higher numbered item.

[0089] As used herein, a system, device, structure, article, element, component, or hardware that is "configured to" perform a specified function is indeed capable of performing the specified function without any changes, rather than having only the potential to perform the specified function after further modification. In other words, a system, device, structure, article, element, component, or hardware that is "configured to" perform a specified function is specifically selected, created, implemented, utilized, programmed, and / or designed for the purpose of performing the specified function. As used herein, "configured to" represents an existing feature of a system, device, structure, article, element, component, or hardware that enables the system, device, structure, article, element, component, or hardware to perform the specified function without further modification. For the purposes of this disclosure, a system, device, structure, article, element, component, or hardware that is described as "configured to" perform a specific function may be additionally or alternatively described as "suitable for" and / or "operable to" perform the function.

[0090] The schematic flow chart included herein is generally described as a logical flow chart. In this way, the depicted order and the marked steps indicate an example of the proposed method. Other steps and methods that are equivalent to one or more steps or parts thereof of the method shown in function, logic or effect can be envisioned. In addition, the format and symbols adopted are provided to explain the logical steps of the method, and are understood to not limit the scope of the method. Although various arrow types and line types can be adopted in the flow chart, it should be understood that they do not limit the scope of the corresponding method. In fact, some arrows or other connectors can be used to indicate only the logical flow of the method. For example, an arrow can indicate a waiting or monitoring period of unspecified duration between the enumerated steps of the depicted method. In addition, the order in which a particular method occurs may strictly comply with or may not strictly comply with the order of the corresponding steps shown.

[0091] Without departing from the spirit or essential features of the present invention, the subject matter may be implemented in other specific forms. The described examples are considered to be illustrative and non-restrictive in all respects. All changes that fall within the equivalent meaning and scope of the claims should be included in the scope of the claims.

[0092] Furthermore, the present disclosure includes implementations according to the following clauses:

[0093] Clause 1. A scintillator for use in an x-ray backscatter system (102), the scintillator (110) comprising:

[0094] An inorganic scintillator portion (112), the inorganic scintillator portion (112) being made of an inorganic scintillating material and comprising one or more inorganic material elements (202), wherein each of the one or more inorganic material elements (202) comprises:

[0095] an outer surface (204) configured to be proximate to an object (120) to be scanned using the x-ray backscatter system (102), wherein the outer surface (204) is configured to receive

[0096] X-ray photons (122) reflected by the object (120); and

[0097] an inner surface (206), the inner surface (206) being opposite to the outer surface (204); and

[0098] An organic scintillator portion (114), the organic scintillator portion (114) being made of an organic scintillating material and comprising a front surface (208), wherein at least a portion of the front surface (208) is adjacent to the inner surface (206) of at least one of the one or more inorganic material elements (202).

[0099] Clause 2. The scintillator (110) according to clause 1, wherein:

[0100] The inorganic scintillator portion (112) further includes a plurality of inorganic material elements (202) spaced apart from each other; and

[0101] The plurality of inorganic material elements (202) are disposed on correspondingly spaced apart first portions (212) of the front surface (208) of the organic scintillator portion (114), wherein a second portion (214) of the front surface (208) of the organic scintillator portion (114) is free of the inorganic material elements (202).

[0102] Item 3. A scintillator (110) according to Item 2, wherein the spaced-apart first portion (212) of the front surface (208) of the organic scintillator portion (114) is recessed relative to the second portion (214) of the front surface (208) of the organic scintillator portion (114) that is free of the inorganic scintillating material.

[0103] Clause 4. A scintillator (110) according to any one of clauses 1 to 3, wherein the inorganic scintillator portion (114) includes an inorganic material element (202) disposed on substantially all of the front surface of the front surface (208) of the organic scintillator portion (114).

[0104] Clause 5. The scintillator (110) according to any one of clauses 1 to 4, wherein the inorganic scintillating material has a refractive index different from a refractive index of the organic scintillating material.

[0105] Clause 6. The scintillator (110) according to any one of clauses 1 to 5, further comprising a second inorganic scintillator portion (216) made of a second inorganic scintillating material, wherein:

[0106] The organic scintillator portion (114) further includes a rear surface (210) opposite to the front surface (208); and

[0107] The second inorganic scintillator portion (216) is disposed on the rear surface (210) of the organic scintillator portion (114).

[0108] Clause 7. The scintillator (110) of Clause 6, wherein the inorganic scintillating material and the second inorganic scintillating material are the same.

[0109] Clause 8. The scintillator (110) according to any one of clauses 6 to 7, further comprising a third inorganic scintillator portion (218) made of a third inorganic scintillating material, wherein:

[0110] The organic scintillator portion (114) further includes one or more side surfaces (220) extending between the front surface (208) and the rear surface (210); and

[0111] The third inorganic scintillator portion (218) is disposed on the one or more side surfaces (220) of the organic scintillator portion (114).

[0112] Clause 9. The scintillator (110) according to any one of clauses 1 to 8, wherein the organic scintillating material comprises one or more of plastic and polyurethane.

[0113] Clause 10. A scintillator (110) according to any one of clauses 1 to 9, wherein the inorganic scintillating material comprises one or more of lead iodide (PbI2), calcium tungstate (CaWO4) and cesium iodide (CsI).

[0114] Clause 11. The scintillator (110) according to any one of clauses 1 to 10, wherein:

[0115] Each of the one or more inorganic material elements (202) has a thickness (T1) defined between the outer surface (204) and the inner surface (206); and

[0116] The thickness (T1) corresponds to the energy of x-rays emitted by the x-ray backscatter system (102).

[0117] Clause 12. The scintillator (110) according to any one of clauses 1 to 11, wherein:

[0118] The organic scintillator portion (114) further includes a rear surface (210) opposite to the front surface (208);

[0119] The organic scintillator portion (114) is configured with a thickness (T2) defined between the front surface (208) and the rear surface (210); and

[0120] The thickness (T2) corresponds to the energy of x-rays used in the x-ray backscatter system (102).

[0121] Clause 13. The scintillator (110) according to any one of Clauses 1 to 12, wherein the organic scintillating portion (114) couples the inorganic scintillating portion (112) with a photomultiplier tube (116).

[0122] Clause 14. A method (500) of manufacturing a scintillator, the method comprising:

[0123] An organic scintillating material layer (402) is provided (502) on a substrate (404), wherein:

[0124] The organic scintillating material layer (402) includes a front surface (208) and a rear surface (210) adjacent to the substrate (404); and

[0125] The organic scintillating material layer (402) defines a plurality of voids (406) at the front surface (208); and

[0126] One or more inorganic material elements (408) are disposed (504) within one or more voids in the plurality of voids (406).

[0127] Item 15. A method (500) according to Item 14, wherein providing (502) an organic scintillating material layer (402) on a substrate (404) comprises: removing (502a) an amount of the organic scintillating material at a plurality of locations on the front surface (208), the removed amount of organic scintillating material defining the plurality of gaps (406) at the front surface (208).

[0128] Clause 16. The method (500) of any one of Clauses 14 to 15, wherein the plurality of voids (406) have a thickness (T3) between 1 micrometer and 100 micrometers.

[0129] Clause 17. The method (500) according to any one of clauses 14 to 16, wherein:

[0130] The organic scintillating material layer (402) has a thickness (T2) defined between the front surface (208) and the rear surface (210); and

[0131] The thickness (T2) of the organic scintillating material layer (402) is between 1 inch and 10 inches.

[0132] Clause 18. A method (600) of operating an x-ray backscatter system (102), the method (600) comprising the steps of:

[0133] transmitting (602) x-rays toward an object (120) via an x-ray tube (104) of the x-ray backscatter system (102); and

[0134] detecting (604) one or more x-rays (122) scattered by the object (120) via a scintillator (110) of the x-ray backscatter system (102);

[0135] Wherein, the scintillator (110) comprises:

[0136] An inorganic scintillator portion (112), the inorganic scintillator portion (112) being made of an inorganic scintillating material and comprising one or more inorganic material elements (202), wherein each of the one or more inorganic material elements (202) comprises:

[0137] an outer surface (204) proximate to the object (120) and an inner surface (206) opposite to the outer surface (204); and

[0138] An organic scintillator portion (114), the organic scintillator portion (114) being made of an organic scintillating material and comprising a front surface (208), wherein at least a portion of the front surface (208) is adjacent to the inner surface (206) of at least one of the one or more inorganic material elements (202).

[0139] Clause 19. The method of clause 18, wherein detecting one or more x-rays (122) scattered by the object (120) comprises:

[0140] receiving (604a) at least one x-ray of the one or more x-rays (122) via the inorganic scintillator portion (112);

[0141] generating (604b) photoemission within the scintillator (110) in response to receiving the at least one x-ray of the one or more x-rays (122); and

[0142] The photoemission is detected (604c) via a photomultiplier tube (116) of the x-ray backscatter system (102).

[0143] Clause 20. The method according to any one of clauses 18 to 19, further comprising providing (606) information that can be used to generate an x-ray image (126) of the object (120) to an imaging device (124) based on the sending (602) and the detecting (604).

Claims

1. A scintillator for use in an x-ray backscatter system (102), the scintillator (110) comprising: An inorganic scintillator portion (112), the inorganic scintillator portion (112) being made of an inorganic scintillating material and comprising one or more inorganic material elements (202), wherein each of the one or more inorganic material elements (202) comprises: an outer surface (204) configured to be proximate to an object (120) to be scanned with the x-ray backscatter system (102), wherein the outer surface (204) is configured to receive x-ray photons (122) reflected from the object (120); and an inner surface (206), the inner surface (206) being opposite to the outer surface (204); and an organic scintillator portion (114), the organic scintillator portion (114) being made of an organic scintillating material and comprising a front surface (208), wherein at least a portion of the front surface (208) abuts against the inner surface (206) of at least one of the one or more inorganic material elements (202), in: The inorganic scintillator portion (112) further includes a plurality of inorganic material elements (202) spaced apart from each other; and The plurality of inorganic material elements (202) are disposed on correspondingly spaced apart first portions (212) of the front surface (208) of the organic scintillator portion (114), wherein a second portion (214) of the front surface (208) of the organic scintillator portion (114) is free of the inorganic material elements (202).

2. The scintillator (110) according to claim 1, wherein: The spaced-apart first portion (212) of the front surface (208) of the organic scintillator portion (114) is recessed relative to the second portion (214) of the front surface (208) of the organic scintillator portion (114) that is free of the inorganic scintillating material.

3. The scintillator (110) according to claim 1 or 2, wherein: The inorganic scintillating material has a refractive index different from a refractive index of the organic scintillating material.

4. The scintillator (110) according to claim 1, further comprising a second inorganic scintillator portion (216) made of a second inorganic scintillating material, wherein: The organic scintillator portion (114) further includes a rear surface (210) opposite to the front surface (208); and The second inorganic scintillator portion (216) is disposed on the rear surface (210) of the organic scintillator portion (114).

5. The scintillator (110) according to claim 4, wherein: The inorganic scintillating material and the second inorganic scintillating material are the same.

6. The scintillator (110) according to claim 4 or 5, further comprising a third inorganic scintillator portion (218) made of a third inorganic scintillating material, wherein: The organic scintillator portion (114) further includes one or more side surfaces (220) extending between the front surface (208) and the rear surface (210); and The third inorganic scintillator portion (218) is disposed on the one or more side surfaces (220) of the organic scintillator portion (114).

7. A method (500) for manufacturing the scintillator according to claim 1, the method (500) comprising the following steps: An organic scintillating material layer (402) is provided (502) on a substrate (404), wherein: The organic scintillating material layer (402) includes a front surface (208) and a rear surface (210) adjacent to the substrate (404); and The organic scintillating material layer (402) defines a plurality of voids (406) at the front surface (208); as well as One or more inorganic material elements (408) are disposed (504) within one or more voids in the plurality of voids (406).

8. A method (600) of operating an x-ray backscatter system (102), the method (600) comprising the steps of: transmitting (602) x-rays toward an object (120) via an x-ray tube (104) of the x-ray backscatter system (102); and One or more x-rays (122) scattered by the object (120) are detected (604) via the scintillator (110) of claim 1 of the x-ray backscatter system (102).

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