초록 ▼

In one embodiment, a scanning unit for inspecting cargo conveyances uses a partial radiation beam and a detector of reduced length. In another embodiment, a scanning unit for inspecting objects comprises a detector with gaps along its expanse. In both cases, the cost of the scanning system may be re

In one embodiment, a scanning unit for inspecting cargo conveyances uses a partial radiation beam and a detector of reduced length. In another embodiment, a scanning unit for inspecting objects comprises a detector with gaps along its expanse. In both cases, the cost of the scanning system may be reduced. The object, the source, and or the detector may be moved to enable generation of computed tomographic images. Methods are disclosed, as well.

대표청구항 ▼

What is claimed is: 1. A scanning unit for inspecting cargo conveyances, the scanning unit comprising: a radiation source to emit a beam of radiation; a rotatable platform configured to support a cargo conveyance for inspection by the beam of radiation, the rotatable platform being rotatable about

What is claimed is: 1. A scanning unit for inspecting cargo conveyances, the scanning unit comprising: a radiation source to emit a beam of radiation; a rotatable platform configured to support a cargo conveyance for inspection by the beam of radiation, the rotatable platform being rotatable about an axis; and a detector positioned to collect at least certain of the radiation transmitted through the cargo conveyance, the detector comprising a plurality of modules separated by at least one gap; wherein: at least one of the platform, the source, or the detector is movable along a direction of the axis; and the plurality of detector modules are positioned with respect to a ray from the source through a center of rotation of the object during rotation by the platform such that a mirror image of first detector modules on one side of the ray, projected onto the other side of the ray, at least coincides with the at least one gap between second detector modules on the other side of the array, to collect a sufficient data set of radiation to reconstruct computed tomographic images. 2. The radiation scanning system of claim 1, wherein: the projection of the mirror image of the first detector modules coincides with the at least one gap and overlaps portions of the second modules; and the system further comprises a processor configured to: apply at least one first weighting value to data collected by overlapping portions of the detector modules; and apply at least one second weighting value to data collected from detector elements in non-overlapping portions of the detector modules; wherein the first weighting value is less than the second weighting value. 3. The scanning unit of claim 1, further comprising a processor coupled to the detector to reconstruct computed tomography images from data received from the detector. 4. The scanning unit of claim 1, wherein: the beam is a cone beam or a fan beam. 5. The scanning unit of claim 4, wherein: the beam is a cone beam and the detector comprises a detector array comprising a plurality of two dimensional detectors. 6. The scanning unit of claim 1, wherein: the source and the detector are stationary; and the platform is movable along the axis. 7. A scanning unit for inspecting objects, the scanning unit comprising: a radiation source to emit a beam of radiation; a rotatable platform to support an object for inspection by the beam of radiation, the rotatable platform being rotatable about an axis; and a detector array positioned to receive radiation transmitted through the object, the detector array comprising a first plurality of modules separated by a second plurality of gaps; wherein: the plurality of modules are positioned with respect to a ray from the source through a center of rotation of the object during rotation by the platform such that a mirror image of first detector modules on one side of the ray, projected onto the other side of the ray, at least coincides with the gaps between second detector modules on the other side of the array; and at least one of the radiation source, the platform and or the detector is movable along a direction of the axis. 8. The scanning unit of claim 7, wherein: the radiation beam is a fan beam. 9. The scanning unit of claim 7, wherein: the radiation beam is a cone beam; and the detector array comprises a plurality of rows and columns of detector modules separated by respective first gaps between detector modules in adjacent rows and by respective second gaps between detector modules in adjacent columns; wherein: the rows of detector modules are positioned so that a first projection of the detector modules on one side of a first axis perpendicular to the first ray and perpendicular to a direction of the rows, onto the other side of the first axis, at least coincides with the plurality of gaps on the other side; and the columns are positioned so that a projection of the detector modules on one side of a second axis perpendicular to the first ray and perpendicular to a direction of the columns onto the other side of the axis at least coincides with the plurality of gaps on the other side. 10. The scanning unit of claim 7, wherein: the source and the detector are stationary; and the platform is movable along the axis. 11. The scanning unit of claim 7, further comprising: a processor programmed to reconstruct computed tomographic images based, at least in part, on radiation collected by the detector array. 12. The radiation scanning system of claim 7, wherein: the projection of the mirror image of the first detector modules coincides with the gaps and overlaps portions of the second modules; and the processor is configured to: apply at least one first weighting value to data collected by overlapping portions of the detector modules; and apply at least one second weighting value to data collected from detector elements in non-overlapping portions of the detector modules; wherein the first weighting value is less than the second weighting value. 13. The scanning unit of claim 7, wherein: each of the plurality of modules comprises detector elements and at least one electronics section; and the scanning unit further comprises a collimator coupled to the source, the collimator defining a plurality of openings, at least some of the openings corresponding to respective modules of the detector array; the openings being configured to allow passage of radiation to irradiate the detector elements of a respective module and not to allow passage of radiation to irradiate the at least one electronics section of the module. 14. A radiation scanning system comprising: a radiation source; a detector comprising an expanse of detector modules and defining at least one gap between adjacent detector modules along the expanse; a movable platform to support the object; and a processor to reconstruct computed tomographic images based, at least in part, on data provided by the detector; wherein: the at least one gap is positioned such that at least some line integrals through the object are measured only once. 15. The radiation scanning system of claim 13, wherein: the at least one gap is positioned such that a mirror image of the expanse of first detector modules on one side of a ray from the source through the object, projected onto the other side of the ray, at least coincides with the at least one gap between second detector modules on the other side of the ray. 16. The radiation scanning system of claim 15, wherein: in the projection, the first detector modules overlap respective portions of the second modules; and the processor is configured to: apply at least one first weighting value to data collected by overlapping portions of the detector modules; and apply at least one second weighting value to data collected from detector elements in non-overlapping portions of the detector modules; wherein the first weighting value is less than the second weighting value. 17. The scanning unit of claim 14, wherein: the radiation source is movable around the object; the detector array is movable with movement of the source; and the detector array extends only partially around the object. 18. The scanning unit of claim 14, wherein: the radiation source is movable around the object; the detector array is stationary; and the detector array extends completely around the object. 19. The radiation scanning system of claim 14, wherein the processor is further programmed to: reconstruct the computed tomographic images by weighting the collected data. 20. The radiation scanning system of claim 14, wherein: a plurality of gaps are defined by spaces between selected adjacent detector modules. 21. A method of examining contents of a cargo conveyance, comprising: rotating the cargo conveyance about an axis of rotation; moving at least one of the cargo conveyance, a source of a beam of radiation, or a detector along the axis; scanning the cargo conveyance with a radiation beam; and measuring at least some line integrals though the cargo conveyance only once by: detecting radiation in at least one first location on one side of the ray passing through the object and not in at least one second other location; detecting radiation in at least one third location on the other side of a ray and not in at least one fourth location; wherein: in a projection of a mirror image of the one side of the ray onto the other side of the ray, the at least one first location on the one side at least coincides with the at least one fourth location on the other side; the method further comprising reconstructing computed tomographic images based on the detected radiation. 22. The method of claim 21, further comprising: rotating the cargo conveyance about an axis; and moving at least one of the cargo conveyance, the source and the detector in a direction of the axis. 23. The method of claim 21, further comprising: moving at least one of the source and the detector around the object; and moving the cargo conveyance through the radiation beam. 24. A method of examining contents of an object, comprising: scanning the object with a radiation beam from a source; detecting radiation in at least one first location on one side of the ray passing through the object and not in at least one second other location; detecting radiation in at least one third location on the other side of a ray and not in at least one fourth location; wherein: in a projection of a mirror image of the one side of the ray onto the other side of the ray, the at least one first location on the one side at least coincides with the at least one fourth location on the other side. 25. The method of claim 24, comprising: detecting radiation interacting with the object by a first plurality of detector modules separated by at least one gap. 26. The method of claim 24, wherein: in the projection, the at least one first location coincides with the at least one fourth location and overlaps a portion of the at least one third location. 27. The method of claim 24, wherein the at least one first location comprises a plurality of detector modules and the at least one third location comprises a plurality of detector modules, the method comprising reconstructing tomographic images by: applying at least one first weighting value to data collected by overlapping portions of the detector modules; and applying at least one second weighting value to data collected by non-overlapping portions of the detector modules; wherein the at least one first weighting value is less than the at least one second weighting value. 28. The method of claim 24, comprising: moving the source around the object while scanning. 29. The method of claim 28, comprising: detecting the radiation by a stationary detector array extending around the object. 30. The method of claim 28, wherein the detector array extends partially around the source, the method comprising: moving the detector array with movement of the source; and detecting the radiation by the moving detector array. 31. A scanning unit for inspecting cargo conveyances, the scanning unit comprising: a radiation source to emit a beam of radiation; a rotatable platform configured to support a cargo conveyance for inspection by the beam of radiation; a collimator configured to collimate the beam of radiation such that the beam of radiation has a first boundary extending beyond an edge of the cargo conveyance and a second boundary intercepting the cargo conveyance during rotation of the cargo conveyance; a detector positioned to collect at least certain of the radiation transmitted through the cargo conveyance; a processor coupled to the detector, the processor configured to reconstruct computed tomographic images based, at least in part, on the radiation detected by the detector; wherein: at least one of the platform, the source, and or the detector is movable along a direction of the axis; and the detector is configured to collect a sufficient data set of radiation to reconstruct computed tomographic images. 32. The system of claim 31, wherein the processor is configured to: apply at least one first weighting value to line integrals collected by the detector once; and apply at least one second weighting factor to line integrals collected by the detector more than once, the second weighting factor being smaller than the first weighting factor. 33. The scanning unit of claim 31, wherein: the source and the detector are stationary; and the platform is movable along the axis. 34. The system of claim 31, wherein the processor is configured to: apply at least one first weighting value to line integrals collected by the detector once; and apply at least one second weighting factor to line integrals collected by the detector more than once, the second weighting factor being smaller than the first weighting factor. 35. A method of inspecting cargo conveyances, comprising: rotating a cargo conveyance about an axis; collimating a radiation beam to have a first boundary extending beyond an edge of the cargo conveyance and a second boundary intercepting the cargo conveyance during rotation of the cargo conveyance; moving at least one of the cargo conveyance, the source or the detector along a direction of the axis; detecting at least certain of the radiation detected by the detector; and reconstructing computed tomographic images from the detected radiation. 36. The method of claim 35, further comprising: applying at least one first weighting value to line integrals collected by the detector once; and applying at least one second weighting factor to line integrals collected by the detector more than once, the second weighting factor being smaller than the first weighting factor. 37. The method of claim 35, further comprising: moving the rotating platform along the axis. 38. A scanning unit for inspecting cargo conveyances, the scanning unit comprising: an X-ray radiation source to emit a beam of radiation; a rotatable platform configured to support a cargo conveyance for inspection by the beam of radiation, the platform being rotatable about an axis and movable along a direction of the axis, in steps; a collimator configured to collimate the beam of radiation such that the beam of radiation has a first boundary extending beyond an edge of the cargo conveyance and a second boundary intercepting the cargo conveyance during rotation of the cargo conveyance; a detector positioned to collect a sufficient data set of radiation transmitted through the cargo conveyance to reconstruct computed tomographic images; and a processor coupled to the detector, the processor configured to reconstruct computed tomographic images based, at least in part, on the radiation detected by the detector. 39. A method of inspecting cargo conveyances, comprising: rotating a cargo conveyance about an axis; collimating a radiation beam to have a first boundary extending beyond an edge of the cargo conveyance and a second boundary intercepting the cargo conveyance during rotation of the cargo conveyance; moving the cargo conveyance along a direction of the axis, in steps; detecting at least certain of the radiation detected by the detector; and reconstructing computed tomographic images from the detected radiation. 40. The method of claim 39, further comprising: applying at least one first weighting value to line integrals collected by the detector once; and applying at least one second weighting factor to line integrals collected by the detector more than once, the second weighting factor being smaller than the first weighting factor.