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Title: Radiographic imaging system for high energy radiation
Claims: What is claimed is: 1. An imaging system comprising: means for detecting high energy radiation emanating from a source of such radiation; means for spatially modulating said radiation, said modulating means having regions which are relatively opaque to said radiation interspersed among regions relatively transparent to said radiation, the depths of said opaque regions being less than the spacing between said opaque regions to permit shadows of said opaque regions cast by rays of radiation emanating from one part of said source to overlap a shadow of said opaque regions cast by rays of radiation emanating from a second part of said source spaced apart from said first part of said source, said modulating means being positioned between said source and said detecting means; means for imparting a relative motion between said detecting means and said modulating means, said detecting means including means for providing an array of data points having data relative to an image of the shadows cast by said modulating means; and means coupled to said detecting means for reconstructing from said array of data points a true image of said source. 2. A system according to claim 1 wherein said motion means comprises means for imparting a translation of said detecting means relative to said modulating means. 3. A system according to claim 1 wherein said motion means includes means for imparting both a translation and a rotation of said detecting means relative to said modulating means. 4. A system according to claim 3 wherein said detecting means detects the positions relative to said detecting means of quanta of radiation incident thereupon and provides signals having data of said positions, and wherein said reconstructing means includes a coordinate converter coupled to said detecting means for converting said position data signals to provide data of said positions relative to a fixed reference frame. 5. An imaging system comprising: means for detecting high energy radiation emanating from a source of such radiation; means for spatially modulating said radiation, said modulating means having regions which are relatively opaque to said radiation interspersed among regions relatively transparent to said radiation, the depths of said opaque regions being less than the spacing between said opaque regions to permit shadows of said opaque regions cast by rays of radiation emanating from one part of said source to overlap a shadow of said opaque regions cast by rays of radiation emanating from a second part of said source spaced apart from said first part of said source, said modulating means being positioned between said source and said detecting means; means for imparting a relative motion between said detecting means and said modulating means, said motion means including means for imparting both a translation and a rotation of said detecting means relative to said modulating means, said detecting means including means for providing an array of data points having data relative to an image of the shadows cast by said modulating means, said detecting means detecting the positions relative to said detecting means of quanta of radiation incident thereupon and providing signals having data of said positions; means coupled to said detecting means for reconstructing from said array of data points a true image of said source, said reconstructing means including a coordinate converter coupled to said detecting means for converting said position data signals to provide data of said positions relative to a fixed reference frame; and wherein said modulating means comprises a mask having an off-axis Fresnel pattern. 6. A system according to claim 5 wherein said modulating means further comprises a second mask spaced apart from said first mask and having a straight zone pattern. 7. A system according to claim 6 wherein said reconstruction means includes means coupled to said coordinate converter means for forming a photographic image of said shadow cast upon said detecting means. 8. A system according to claim 7 wherein said photographic image is formed on a transparency, and wherein said reconstruction means further includes a decoder which comprises: an optical system for transmitting an illuminating beam of light through said transparency; and telescope means for viewing light propagating through said transparency along an axis inclined to an axis of said illuminating beam. 9. A system according to claim 4 wherein said modulating means has a mask having an array of regions arranged in a first direction with monotonically increasing sizes and arranged in a second direction with monotonically increasing sizes. 10. A system according to claim 9 wherein the regions of said mask are relatively opaque to said radiation. 11. A system according to claim 9 wherein said regions are relatively transparent to said radiation. 12. A system according to claim 9 wherein said regions include regions which are relatively opaque to said radiation interspersed among regions which are relatively transparent to said radiation. 13. A system according to claim 12 wherein said reconstructing means comprises: means coupled to said coordinate converter for storing an array of data points obtained therefrom; means for scanning said array of data points of said storing means at a predetermined rate; and means coupled to said scanning means for filtering a signal obtained therefrom, said filtering means having a temporal impulse response inverse to the pattern of said array of regions of said mask to provide said true image. 14. A system according to claim 13 further comprising means coupled to said filtering means of said reconstructing means for displaying said true image, said display means being synchronized with said scanning means of said reconstructing means. 15. A system according to claim 12 wherein said modulating means has a second mask adjacent said first mask, said second mask having an array of relatively opaque and relatively transparent regions arranged substantially in a checkerboard pattern. 16. A system according to claim 4 wherein said modulating means has an array of circular zone shaped regions relatively opaque to said radiation spaced apart from each other and arranged such that the circular zones of said array of successively larger radii have successively larger widths as measured between the inner and outer radii of each zone. 17. A system according to claim 16 wherein said reconstructing means includes means for forming a photographic image of said shadow cast upon said detecting means. 18. A system according to claim 17 wherein said photographic image is a transparency, and wherein said reconstructing means has a decoder which comprises: an optical system for illuminating said transparency, said optical system including a lens positioned adjacent said transparency for focussing light which propagates through said transparency to a focal point behind said lens; and a prism in the shape of a right circular cone positioned with its axis coaxial to the beam of light illuminating said transparency, said prism being positioned at said focus with the base of the prism facing said lens, said lens and said prism providing an inverse transformation of said shadow cast upon said detecting means to provide said true image. 19. A system according to claim 1 wherein said modulating means comprises a mask having said opaque and said transparent regions, and said motion means comprises means for translating said mask relative to said detecting means in a first direction and for translating said mask and said detecting means relative to said source in a second direction. 20. A system according to claim 19 wherein said first direction is perpendicular to said second direction. 21. A system according to claim 20 wherein said modulating means comprises a second mask positioned adjacent said first mask, and within the path of propagation of said radiation from said source through said first mask, said second mask having an array of relatively opaque regions and relatively transparent regions, said regions of said first mask being arranged such that the widths of at least some of the regions are monotonically increasing in size. 22. A system according to claim 21 wherein said first mask moves relative to said second mask, said relative motion imparting a modulation to the rate at which quanta of radiation from said source impinge upon said detecting means, said reconstructing means comprising means coupled to said detecting means for measuring the rate of occurrence of quanta of said radiation impinging upon said detecting means, and means coupled to said rate measuring means for providing an envelope function of said rate measurements. 23. A system according to claim 22 wherein said reconstructing means comprises means coupled to said envelope detecting means for performing an inverse Fourier transformation of said envelope function to provide said true image. 24. A system according to claim 23 further comprising at least one other of said detecting means and at least one other of said reconstructing means to form a plurality of said true images of which individual ones of said true images correspond to data of respective ones of said detectors; and a display system including means coupled to the transformation means in respective ones of said reconstructing means for shifting the relative positions of said true images in accordance with a preselectable program, and means for combining said shifted true images to provide a composite image of a particular plane within said source. 25. A system according to claim 24 wherein a collimator is placed between one of said masks in said detecting means, said collimator having an array of converging slots directed towards a focal line within said source, and wherein said shifting means comprises a memory for storing each of said true images, a generator for providing addresses for each of the data points for each of said stored true images, and means coupled to said address generator for altering the addresses in a preselectable manner to provide a shifting in said memory of the address locations of said data points, said display system being coupled to said memory for reading out of said memory said stored true images in shifted positions corresponding to the shifting of said addresses. 26. In combination: means for detecting high energy radiation, said detecting means providing signals in response to quanta of radiation incident thereupon; means positioned between said detecting means and a source of said radiation for spatially modulating said radiation, said modulating means comprising regions which are relatively opaque to said radiation and having an array of apertures therein which are relatively transparent to said radiation; and means coupled to said modulating means for varying the sizes of said apertures to provide said detector signals with data suitable for forming an image of said source. 27. A combination according to claim 26 wherein the apertures in one part of said array differ in size from the apertures in the other part of said array at one instant of time, rays of said radiation passing through a plurality of said apertures while propagating from said source to said detecting means. 28. A combination according to claim 27 wherein said detecting means includes means for measuring the rate of occurrence of said quanta of radiant energy which are incident upon said detecting means, a sequence of said detector signals having an envelope representing a transformation of a line scan image of said source. 29. A combination according to claim 28 further comprising means coupled to said detecting means for extracting said envelope. 30. A combination according to claim 29 wherein said envelope extracting means conprises: a memory coupled to said rate measuring means for storing said detector signals; means coupled to said memory means for performing arithmetic calculations with said stored signals for determining the locations of peak values of said envelope; and storage means coupled to said arithmetic means for storing said peak values, each of said peak values being a data point of said envelope. 31. A combination according to claim 30 further comprising transformation means coupled to said envelope extracting means for performing a transformation of said envelope to provide a true image of said source. 32. A combination according to claim 31 wherein said envelope is a Fourier transform of a line scan image of said source, and said transformation means provides an inverse Fourier transform. 33. A method of radiographic imaging comprising the steps of: inserting radiation responsive material from the class of ingestable materials consisting of radio-opaque materials and radiation emissive materials into a subject; positioning a plurality of detectors of said radiation at a position fixed relative to said subject; moving a plurality of barrier elements which impede the propagation of quanta of said radiation between said subject and said plurality of detectors, said detectors providing signals in response to radiation propagating from said subject past said barrier elements to said detectors, said barrier elements spatially modulating said propagation of said radiation; and decoding modulated signals provided by said detectors whereby an image of a radiation pattern emanating from said subject is provided for each of said detectors. 34. a method according to claim 33 further comprising the step of: repositioning the decoded image obtained from one detector relative to the coded image obtained from a second of said detectors for viewing a laminograph of a plane within said subject. 35. A method according to claim 34 comprising the step of: relocating said detectors and said barrier elements relative to said subject to provide an image of another portion of said subject. 36. An imaging system comprising: means for detecting high energy radiation emanating from a source of such radiation; means for spatially modulating said radiation, said modulating means having regions which are relatively opaque to said radiation interspersed among regions relatively transparent to said radiation, the depths of said opaque regions being less than the spacing between said opaque regions to permit shadows of said opaque regions cast by rays of radiation emanating from one part of said source to overlap a shadow of said opaque regions cast by rays of radiation emanating from a second part of said source spaced apart from said first part of said source, said modulating means being positioned between said source and said detecting means; means for imparting a relative motion between said detecting means and said modulating means, said detecting means summing together the signals of the respective shadow patterns, said detecting means including means for providing an array of data points from said summed signals having data relative to an image of the sum of the shadows cast by said modulating means; and means coupled to said detecting means for reconstructing from said array of data points a true image of said source. 37. a system according to claim 36 wherein said reconstructing means include means for forming a transparency of said data points and means for viewing said transparency at an angle to an axis thereof. 38. A system according to claim 36 wherein said reconstructing means includes means for filtering said array of data points, said filtering means having an impulse response complimentary to the pattern of said opaque regions and said transparent regions of said modulating means. 39. In combination: means for detecting high energy radiation, said detecting means providing signals in response to quanta of radiation incident thereupon; means positioned between said detecting means and a source of said radiation for spatially modulating said radiation, said modulating means comprising regions which are relatively opaque to said radiation and having an array of apertures therein which are relatively transparent to said radiation, said detecting means summing together the signals of shadows cast by said modulating means in response to individual ones of said points of radiation incident thereupon; and means coupled to said modulating means for varying the sizes of said apertures to provide said detector signals with data suitable for forming an image of said source. Other info: Inventors: Barrett, Harrison H. (Lexington, MA, US) Application Number: 465940 Filing Date: 1974-05-01 Publication_date: 1976-02-03 Assignee: Raytheon Company (Lexington, MA) Primary Class(es): 250/369 250/366, 250/505.1, 378/2 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Borchelt, Archie R. Assistant Examiner: Attorney: Warren; David M., Pannone; Joseph D., Bartlett; Milton D. |
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