Patent Number: 
Section: claims

1. An X-ray computed tomography apparatus, comprising: an X-ray generator configured to generate a first X-ray in a pre-scan mode and a second X-ray in an image scan mode;  an X-ray detector configured to detect a first transmission X-ray exposed through a specimen to a first exposure width of the X-ray detector along a body axis of the specimen, resulting from the first X-ray at a first scanning position in the pre-scan mode and to detect a second transmission X-ray exposed through the specimen to a second exposure width of the X-ray detector along the body axis of the specimen, resulting from the second X-ray at a second scanning position in the image scan mode, the first exposure width being narrower than the second exposure width;  a controller configured to control the first scanning position and the second scanning position; and  a display configured to display a first image based on the first transmission X-ray detected by the X-ray detector and a second image based on the second transmission X-ray detected by the X-ray detector. 2. The apparatus according to  claim 1 , further comprising a collimator, provided in between the X-ray generator and the X-ray detector, configured to collimate the first X-ray and the second X-ray, and wherein the controller is further configured to control the collimator to change a collimating width so that the fist transmission X-ray and the second transmission X-ray are exposed to the first exposure width and the second exposure width of the X-ray detector, respectively. claim 1 3. The apparatus according to  claim 1 , wherein the controller is further configured to control the X-ray generator to change a generation angle along the body axis so that the first transmission X-ray and the second transmission X-ray are exposed to the first exposure width and the second exposure width of the X-ray detector, respectively. claim 1 4. The apparatus according to  claim 1 , wherein, when a distance between the X-ray generator and the X-ray detector is variable, the first transmission X-ray is exposed to the first exposure width of the X-ray detector when the distance is a first distance and the second transmission X-ray is exposed to the second exposure width of the X-ray detector when the distance is a second distance longer than the first distance. claim 1 5. The apparatus according to  claim 1 , wherein an intensity of the first X-ray is lower than an intensity of the second X-ray. claim 1 6. The apparatus according to  claim 1 , wherein a number of slices in a single scan in the pre-scan mode is smaller than a number of slices in a single scan in the image scan mode. claim 1 7. The apparatus according to  claim 1 , wherein the X-ray detector comprises a plurality of detecting elements along the body axis; and wherein each scanning slice in the pre-scan mode uses at least two of the plurality of detecting elements. claim 1 8. The apparatus according to  claim 1 , wherein the X-ray detector comprises a plurality of detecting elements along the body axis; and wherein the first exposure width is over a first number of the plurality of detecting elements along the body axis and the second exposure width is over a second number of the plurality of detecting elements along the body axis, the first number being smaller than the second number. claim 1 9. The apparatus according to  claim 8 , further comprising a data acquisition unit, comprising a plurality of data acquisition elements, configured to acquire data output from the X-ray detector; and a switch configured to switch a connection between the plurality of detecting elements and the plurality data acquisition elements, and wherein the connection is kept identical in between the pre-scan mode and the image scan mode. claim 8 10. The apparatus according to  claim 1 , further comprising a data acquisition unit, comprising a plurality of data acquisition elements, configured to acquire data output from the X-ray detector, and wherein a predetermined number of the data acquisition elements are commonly used in both the pre-scan mode and the image scan mode. claim 1 11. The apparatus according to  claim 10 , further comprising a reconstruction unit configured to reconstruct an image based on at least a portion of the data acquired by the data acquisition unit, and wherein a remaining portion of the data acquired by the data acquisition unit is not used for reconstruction by the reconstruction unit in the pre-scan mode. claim 10 12. The apparatus according to  claim 1 , wherein the first scanning position is fixed along the body axis. claim 1 13. The apparatus according to  claim 1 , wherein the second scanning position is movable along the body axis. claim 1 14. The apparatus according to  claim 1 , wherein the second scanning position is achieved by moving at least the X-ray generator and the X-ray detector from the first scanning position relative to the body axis in response to an manual designation by an operator. claim 1 15. The apparatus according to  claim 1 , wherein the second scanning position is achieved by moving at least the X-ray generator and the X-ray detector from the first scanning position relative to the body axis in response to that a CT number of the first image has reached a predetermined reference value. claim 1 16. The apparatus according to  claim 1 , further comprising a calculator configured to calculate a CT number in a predetermined region of the first image, and wherein a scan in the pre-scan mode is automatically terminated when the specimen is injected with a contrast agent and the CT number calculated by the calculator has reached a predetermined reference value. claim 1 17. The apparatus according to  claim 16 , wherein the controller is further configured to change the first scanning position to the second scanning position, responsive to termination of the scan in the pre-scan mode; and wherein a scan in the image scan mode is initiated at the second scanning position in a predetermined time after the termination of the scan in the pre-scan mode. claim 16 18. The apparatus according to  claim 1 , wherein the display is further configured to display a CT number in a predetermined region of the first image in the pre-scan mode. claim 1 19. The apparatus according to  claim 1 , wherein the X-ray detector comprises a plurality of detecting elements along the body axis; and wherein first data based on detection by one of the plurality of detecting elements under the first exposure width are stacked with second data based on detection by at least one other of the plurality of the detecting elements under the first exposure width in the pre-scan mode. claim 1 20. The apparatus according to  claim 19 , further comprising a reconstruction unit configured to reconstruct an image based on third data resulting from the stack of the first data and the second data, and wherein the data stacking in the pre-scan mode is performed before the first data and the second data are supplied to the reconstruction unit. claim 19 21. The apparatus according to  claim 1 , further comprising a data acquisition unit, comprising a plurality of data acquisition elements, configured to acquire data output from the X-ray detector, and wherein the X-ray detector comprises a plurality of detecting elements along the body axis; and wherein at least one of the detecting elements to be used, a slice thickness to be used in a single slice, and at least one of the data acquisition elements to be used are common between the pre-scan mode and the image scan mode. claim 1 22. The apparatus according to  claim 1 , wherein a number of slices in a single scan in the pre-scan mode is smaller than a number of slices in a single scan in the image scan mode according to a difference between the first exposure width and the second exposure width. claim 1 23. The apparatus according to  claim 1 , wherein the X-ray detector comprises a plurality of detecting elements along the body axis; and wherein a number of the detecting elements to be used in the pre-scan mode is smaller than another number of the detecting elements to be used in the image scan mode according to a difference between the first exposure width and the second exposure width. claim 1 24. The apparatus according to  claim 1 , further comprising a data acquisition unit, comprising a plurality of data acquisition elements, configured to acquire data output from the X-ray detector, and wherein the X-ray detector comprises a plurality of detecting elements along the body axis; and wherein each of the plurality of data acquisition elements acquires the data output from one or more of the plurality of detecting elements. claim 1 25. The apparatus according to  claim 1 , further comprising a data acquisition unit, comprising a plurality of data acquisition elements configured to acquire data output front the X-ray detector; and a reconstruction unit configured to reconstruct an image based on the data output acquired by the data acquisition unit; wherein the X-ray detector comprises a plurality of detecting elements along the body axis; and wherein information from one or more of the data acquisition elements not corresponding to detecting elements under the first exposure width is not used as the data output for reconstruction of the image by the reconstruction unit in the pre-scan mode. claim 1 26. The apparatus according to  claim 1 , further comprising an input device configured to input information regarding determining an image scan condition for the image scan mode; and wherein the controller is further configured to determine the image scan condition for the image scan mode based on the information and also to automatically determine a pre-scan condition for the pre-scan mode based on the determined image scan condition. claim 1 27. The apparatus according to  claim 26 , wherein, when a plurality of predetermined pre-scan conditions are prepared, each of which corresponding to each of a plurality of parts of the specimen, for the image scan condition, the controller determines one of the plurality of predetermined pre-scan conditions, as a determined pre-scan condition, which corresponds to one of the plurality of parts indicated in the determined image scan condition. claim 26 28. The apparatus according to  claim 1 , further comprising a reconstruction unit configured to reconstruct an image based on data resulting from detection by the X-ray detector, and wherein the reconstruction unit performs reconstruction in a real time reconstruction manner in the pre-scan mode. claim 1 29. An X-ray computed tomography apparatus, comprising; an X-ray source configured to radiate an X-ray to a specimen;  a collimator configured to vary a collimating width, along a body axis of the specimen, which determines an X-ray width exposed to the specimen;  a detector, comprising a plurality of detecting elements along the body axis, configured to detect a transmission X-ray transmitted from the specimen;  a data acquisition unit, comprising a plurality of data acquisition elements along the body axis, configured to acquire data output from the detector;  is an implementing unit configured to implement a scan around the specimen with the X-ray source and the X-ray detector;  a controller configured to control a scan mode to switch from a pre-scan to an image scan, and to control the collimator to make the collimating width wider in the image scan than in the pre-scan, the pre-scan being for monitoring a CT number in a predetermined region of interest of the specimen, the image scan being for scanning an examining region of the specimen; and  a reconstruction unit configured to reconstruct a tomography of the specimen based on the data output acquired in the pre-scan, and also to reconstruct an image of the specimen based on projection data acquired in the image scan. 30. The apparatus according to  claim 29 , further comprising a switch configured to switch a number of the data acquisition elements to be used; and wherein the controller is further configured to control the switch so that the number of the data acquisition elements to be used is identical in both the pre-scan and the image scan. claim 29 31. The apparatus according to  claim 29 , further comprising: claim 29 a setting unit, when a plurality of slices are obtained in each single rotation of the scanning, configured to set a number of the slices and a slice width common to each of the slices, the slice width being defined as a number of the slices multiplied by a slice thickness common to the each of the slices; and  a switch, provided in between the detector and the data acquisition unit, configured to switch a connection between the detecting elements and the data acquisition elements;  and wherein the controller is further configured to control the switch so as to keep the connection identical in both the pre-scan and the image scan even when the setting unit sets one of the number of the slices and the slice width to be different in between the pre-scan and the image scan. 32. The apparatus according to  claim 31 , wherein the controller is still further configured to control that the data output from at least a predetermined one of the detecting elements to at least one connected data acquisition element are not used in an image reconstruction by the reconstruction unit, the at least predetermined one of the detecting elements being not used in the pre-scan in accordance with the number of the slices and the slice width set by the setting unit. claim 31 33. The apparatus according to  claim 29 , wherein, when a plurality of slices are obtained in each single rotation of the pre-scan and the image scan, the controller is also configured to set a slice thickness common to each of the slices and a condition using the data acquisition elements to be common in both the pre-scan and the image scan, and further configured to set a different number of the detecting elements to be used in between the pre-scan and the image scan. claim 29 34. A method of performing a scan in an X-ray computed tomography apparatus, comprising steps of; generating a first X-ray in a pre-scan mode;  detecting with an X-ray detector a first transmission X-ray exposed through a specimen to a first exposure width of the X-ray detector along a body axis of the specimen, resulting from the first X-ray at a first scanning position in the pre-scan mode;  displaying a first image based on the first transmission X-ray;  generating a second X-ray in an image scan mode;  detecting with the X-ray detector a second transmission X-ray exposed through the specimen to a second exposure width of the X-ray detector along the body axis of the specimen, resulting from the second X-ray at a second scanning position in the image scan mode, the second exposure width being wider than the first exposure width;  displaying a second image based on the second transmission X-ray; and  controlling the first scanning position and the second scanning position. 35. A computer program product on which is stored a computer program for performing a scan in an X-ray computed tomography apparatus, the computer program having instructions, which when executed, perform steps comprising: generating a first X-ray in a pre-scan mode;  detecting with an X-ray detector a first transmission X-ray exposed through a specimen to a first exposure width of the X-ray detector along a body axis of the specimen, resulting from the first X-ray at a first scanning position in the pre-scan mode;  generating a second X-ray in an image scan mode;  displaying a first image based on the first transmission X-ray;  detecting with the X-ray detector a second transmission X-ray exposed through the specimen to a second exposure width of the X-ray detector long the body axis of the specimen, resulting from the second X-ray at a second scanning position in the image scan mode, the second exposure width being wider than the first exposure width;  displaying a second image based on the second transmission X-ray; and  controlling the first scanning position and the second scanning position.