X-ray scanners having source points with less than a predefined variation in brightness
The present application discloses an X-ray scanner having an X-ray source arranged to emit X-rays from source points through an imaging volume. The scanner may further include an array of X-ray detectors which may be arranged around the imaging volume and may be arranged to output detector signals in response to the detection of X-rays. The scanner may further include a conveyor arranged to convey an object through the imaging volume in a scan direction, and may also include at least one processor arranged to process the detector signals to produce an image data set defining an image of the object. The image may have a resolution in the scan direction that is at least 90% as high as in one direction, and in some cases two directions, orthogonal to the scan direction.
1. An X-ray scanner comprising
an X-ray source arranged to emit X-rays from a plurality of source points through an imaging volume, wherein the plurality of source points have a less than 5% variation in brightness between each of the plurality of source points;
an array of X-ray detectors arranged around the imaging volume and arranged to output detector signals in response to the detection of X-rays;
a conveyor arranged to convey an object through the imaging volume in a scan direction; and
at least one processor arranged to process the detector signals to produce an image data set defining an image of the object.
2. The scanner according to claim 1 wherein the image has a resolution in the scan direction which is substantially equal to a resolution in two orthogonal directions.
3. The scanner according to claim 1 wherein each of the plurality of source points are arranged in a plane perpendicular to the scan direction.
4. The scanner according to claim 1 wherein the X-ray detectors of the array are located in a common plane which is perpendicular to the scan direction.
5. The scanner according to claim 1 wherein the array of X-ray detectors is offset from the plurality of source points in the scan direction.
6. The scanner according to claim 1 wherein the array of X-ray detectors is at least two detectors wide in the scan direction.
7. The scanner according to claim 6 wherein the array of X-ray detectors is arranged in a plurality of rings and wherein the rings are in separate planes.
8. The scanner according to claim 7 wherein the planes are spaced from each other in the scan direction.
9. The scanner according to claim 6 wherein the X-ray detectors have a width in a circumferential direction and each of the X-ray detectors is offset in the circumferential direction from one adjacent to it in the scan direction.
10. The scanner according to claim 9 wherein each of the X-ray detectors has a width in the circumferential direction and the offset is less than the width.
11. The scanner according to claim 1 further comprising a controller arranged to activate each of the plurality of source points in a predetermined sequence once in each of a sequence of scan cycles.
12. The scanner according to claim 11 wherein the controller is arranged to control the frequency of the scan cycles so that it takes an integer number of scan periods for the object to move a distance in the scan direction equal to the spacing of the X-ray detectors in the scan direction.
13. The scanner according to claim 12 wherein the integer is greater than 1.
14. The scanner according to claim 11 wherein the scan cycle has a frequency and wherein the frequency is variable such that a resolution in the scan direction can be adjusted.
15. The scanner according to claim 14 wherein the controller is arranged to adjust the scan frequency so as to provide a constant resolution in the scan direction for a plurality of object speeds.
16. The scanner according to claim 1 wherein the conveyor is arranged to convey the object at a speed of at least 0.1 m/s.
17. The scanner according to claim 16 arranged to generate an image data set having a signal to noise ratio of at least 50.
18. The scanner according to claim 17 wherein the image comprises voxels having a size in the scan direction of 5 mm or less.
19. The scanner according to claim 18 wherein the image voxels have a size in two directions orthogonal to the scan direction which is 5 mm or less.
20. A mobile scanning system comprising a vehicle comprising a body and a scanner housed within the body wherein the scanner comprises the X-ray scanner of claim 1 .