X-RAY DETERMINATION OF AN OBJECT’S LOCATION WITHIN A BODY

Abstract

Digital tomosynthesis (DT) gives better diagnostic information than 2D X-ray, rivalling CT. However, tomosynthesis reconstruction requires sophisticated algorithms and a powerful computer, and can take several minutes to complete. The present invention takes a single x-ray image of a body 50 using multiple sources. In normal tomography and tomosynthesis imaging, such overlapping cones would lead to un-reconstructable data as significant overlap, in general, can’t be deconvolved and is not soluble. However, here, for the detection and localization of dense, compact objects 40, a location of an object 40 may be determined in three spatial dimensions from a single two-dimensional image. That is, processor-intensive reconstruction of a three-dimensional volume may be avoided.

Claims

1. A method of determining a location of an object within a body, the method comprising the steps of: providing an x-ray detector panel; providing a first x-ray emitter at a first location relative to the x-ray detector panel, the first x-ray emitter configured to emit a first cone of x-rays therefrom such that the first cone of x-rays impinges the x-ray detector panel; providing a second x-ray emitter at a second location relative to the x-ray detector panel, the second location spaced from the first location, the second x-ray emitter configured to emit a second cone of x-rays therefrom such that the second cone of x-rays impinges the x-ray detector panel; activating the first x-ray emitter and the second x-ray emitter concurrently to produce a single two-dimensional image at the detector panel indicative of absorption of the first and second cones of x-rays by a body placed therebetween; determining in the single two-dimensional image respective first and second positions of an object projected by the first and second cones of x-rays respectively; and establishing a site of the object relative to the x-ray detector panel from the first location, second location, first position and second position, wherein the site of the object is determined in three spatial dimensions from the single two-dimensional image.

2. The method of determining a location of an object within a body of claim 1, the method further comprising the steps of: providing a third x-ray emitter at a third location relative to the x-ray detector panel, the third location spaced from the first and second locations and non-co-linear with the first and second locations, the third x-ray emitter configured to emit a third cone of x-rays therefrom such that the third cone of x-rays impinges the x-ray detector panel; activating the third x-ray emitter concurrently with the first x-ray emitter and the second x-ray emitter to produce the single two-dimensional image at the detector panel indicative of absorption of the first, second and third cones of x-rays by a body placed therebetween; determining in the single two-dimensional image a third position of the object projected by the third cone of x-rays; and establishing a site of the object relative to the x-ray detector panel from the first location, second location, third location, first position, second position and third position.

3. A system for determining a location of an object within a body, the system comprising: an x-ray detector panel; a first x-ray emitter at a first location relative to the x-ray detector panel, the first x-ray emitter configured to emit a first cone of x-rays therefrom such that the first cone of x-rays impinges the x-ray detector panel; a second x-ray emitter at a second location relative to the x-ray detector panel, the second location spaced from the first location, the second x-ray emitter configured to emit a second cone of x-rays therefrom such that the second cone of x-rays impinges the x-ray detector panel; a control device configured to activate the first x-ray emitter and the second x-ray emitter concurrently to produce a single two-dimensional image at the detector panel indicative of absorption of the first and second cones of x-rays by a body placed therebetween; an image analyzer configured to determine in the single two-dimensional image respective first and second positions of an object projected by the first and second cones of x-rays respectively; and a processor configured to establish a site of the object relative to the x-ray detector panel from the first location, second location, first position and second position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. This description is given for the sake of example only, without limiting the scope of the invention. The reference figures quoted below refer to the attached drawings.

[0051] FIG. 1 shows a simplified view of a physical arrangement of components and a resultant image due to three emitters.

[0052] FIG. 2 shows a resultant image due to nine emitters.

[0053] FIG. 3 shows a simplified representation of the location of shrapnel in a patient.

[0054] FIG. 4 shows one possible geometry.

DETAILED DESCRIPTION

[0055] The present invention will be described with respect to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. Each drawing may not include all of the features of the invention and therefore should not necessarily be considered to be an embodiment of the invention. In the drawings, the size of some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

[0056] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that operation is capable in other sequences than described or illustrated herein. Likewise, method steps described or claimed in a particular sequence may be understood to operate in a different sequence.

[0057] Moreover, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that operation is capable in other orientations than described or illustrated herein.

[0058] It is to be noticed that the term “comprising”, used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression “a device comprising means A and B” should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

[0059] Similarly, it is to be noticed that the term “connected”, used in the description, should not be interpreted as being restricted to direct connections only. Thus, the scope of the expression “a device A connected to a device B” should not be limited to devices or systems wherein an output of device A is directly connected to an input of device B. It means that there exists a path between an output of A and an input of B which may be a path including other devices or means. “Connected” may mean that two or more elements are either in direct physical or electrical contact, or that two or more elements are not in direct contact with each other but yet still co-operate or interact with each other. For instance, wireless connectivity is contemplated.

[0060] Reference throughout this specification to “an embodiment” or “an aspect” means that a particular feature, structure or characteristic described in connection with the embodiment or aspect is included in at least one embodiment or aspect of the present invention. Thus, appearances of the phrases “in one embodiment”, “in an embodiment”, or “in an aspect” in various places throughout this specification are not necessarily all referring to the same embodiment or aspect, but may refer to different embodiments or aspects. Furthermore, the particular features, structures or characteristics of any one embodiment or aspect of the invention may be combined in any suitable manner with any other particular feature, structure or characteristic of another embodiment or aspect of the invention, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments or aspects.

[0061] Similarly, it should be appreciated that in the description various features of the invention are sometimes grouped together in a single embodiment,figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Moreover, the description of any individual drawing or aspect should not necessarily be considered to be an embodiment of the invention. Rather, as the following claims reflect, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

[0062] Furthermore, while some embodiments described herein include some features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form yet further embodiments, as will be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0063] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

[0064] In the discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, coupled with an indication that one of said values is more highly preferred than the other, is to be construed as an implied statement that each intermediate value of said parameter, lying between the more preferred and the less preferred of said alternatives, is itself preferred to said less preferred value and also to each value lying between said less preferred value and said intermediate value.

[0065] The use of the term “at least one” may mean only one in certain circumstances. The use of the term “any” may mean “all” and/or “each” in certain circumstances.

[0066] The principles of the invention will now be described by a detailed description of at least one drawing relating to exemplary features. It is clear that other arrangements can be configured according to the knowledge of persons skilled in the art without departing from the underlying concept or technical teaching, the invention being limited only by the terms of the appended claims.

[0067] FIG. 1 shows in the upper portion an emitter array 1, a detector panel 2, and an object 3 disposed therebetween. Three respective cones 11, 12, 13 of x-ray radiation are shown emanating from three respective x-ray emitters (not shown) in the emitter array 1. Three respective images 31, 32, 33 are shown on the detector panel 2, due to the three respective cones 11, 12, 13.

[0068] In the lower portion of FIG. 1, the three respective images 31, 32, 33 are again shown as they would appear on the detector panel 2. The projections of the cones 11, 12 13 onto the detector panel 2 are also indicated.

[0069] FIG. 2 shows a resultant image, similar to that shown in the lower portion of FIG. 1, due to nine emitters of the emitter array 1 being activated to produce nine images of the object 3 on the detector panel 2, with the corresponding cone projections 10. It should be noted that the geometry of FIG. 2 is different to that of FIG. 1, resulting in a different spacing of the images 30 on the detector panel 2 with respect to the cone projections 10.

[0070] It should also be noted that FIGS. 1 and 2 show the resultant image due to a well-defined, spatially small object, compared to the cone projection and/or overlap. Such resultant images show multiple discrete instances of the single object’s projection. However, where the object to be imaged is large compared to the cone projection and/or overlap, the resultant image would not show multiple discrete instances of the object’s projection, but instead the single object’s projections may overlap one another. In circumstances where a relatively large number of emitters are used (e.g. four, five, six or more), in particular, the resultant image of the object may appear indistinct and/or blurred, particularly at the edges. In such cases, the site of the object may still be established by similar trigonometric procedures, for example taking account of an amount of blurring at a periphery of the object’s projection.

[0071] FIG. 3 shows a simplified representation of the location of shrapnel 40 in a patient 50, shown in the coronal plane to the left and in the sagittal plane to the right. A grid 60 is overlaid in each view to show the regions covered by the x-ray cones (not shown), and to help identify accurate locations.

[0072] FIG. 4 shows one possible geometry used between the emitter array 1 and the detector panel 2, shown parallel and spaced apart a distance D. An elongate object 70 is shown therebetween, illuminated by two respective emitters shown at x1 and x3. An image of the elongate object 70 is indicated on the detector panel 2 by Lx.

[0073] To calculate the depth of the elongate object 70 where only two emitters are used, first the angles α and β in FIG. 4 may be calculated:

$\alpha =arcsin\left[\frac{D}{{\left(x_1-x_2\right)}^2+D^2}\right]$

$\beta =arcsin\left[\frac{D}{{\left(x_3-x_4\right)}^2+D^2}\right]$

[0074] This may be repeated for any edge points of the elongate object 70. From these angles the depth, d, of the elongate object 70 at the edge point can be calculated using:

$d=\frac{x}{\frac{1}{tan\left(\alpha \right)}+\frac{1}{tan\left(\beta \right)}}$

[0075] The depth may also be calculated for each edge point on the elongate object 70. The length of the elongate object can be calculated using the depth and the total length of the dark spot on the detector:

$l_x=L_x\frac{D-d}{d}$

[0076] Other triangulation methods are contemplated. For instance, shift and add methods are well known from tomosynthesis.

[0077] The X-ray panel source could also be multi-paneled or curved such that it could be on wheels and rolled over the patient. The geometry would be modified from the original method in this instance and a modified method of triangulation used, as would be well understood by the skilled person.