Patent Number: 
Section: description

Referring now to the accompanying drawings, there is shown a preferred embodiment of the invention. FIG. 1 is a diagram to show the configuration of a computer tomography apparatus according to an embodiment of the invention. FIG. 1 shows a mechanical configuration of the computer tomography apparatus with a schematic drawing and an electric configuration thereof with a block diagram. The computer tomography apparatus has an X-ray source 1, a two-dimensional X-ray detector 2 and a turn table 3. The X-ray source 1 is placed in a state in which an X-ray optical axis L of the X-ray source is directed in a horizontal direction (x direction). The two-dimensional X-ray detector 2 is placed on the X-ray optical axis L so that it is opposed to the X-ray source 1. The turn table 3 is placed between the X-ray source 1 and the two-dimensional X-ray detector 2. The X-ray source 1 is driven and controlled by a tube voltage and a tube current supplied from an X-ray controller 11, and outputs a cone-like X-ray beam along the horizontal optical axis L. The X-ray controller 11 contains a high-voltage generation circuit and is controlled by a control section 40. The two-dimensional X-ray detector 2 includes an image intensifier 21 and a CCD camera 22. Each pixel data outputted from the CCD camera 22 is input to a data processing section 45. The two-dimensional X-ray detector 2 can be moved in the x direction by driving a detector move mechanism 2a comprising a motor (not shown). That is, the two-dimensional X-ray detector 2 can be moved toward or away from the X-ray source 1. The turn table 3 mounts a target object W to be examined thereon and rotates the target object W. That is, the turn table 3 can be rotated around a rotation axis thereof, namely, along a vertical direction (z direction) by driving an internal motor (not shown). The turn table 3 can be moved in the z direction, namely, a rotation axis direction by driving a z direction move mechanism 3a comprising a motor (not shown). The turn table 3 also can be moved in the x direction by driving an x direction move mechanism 3b comprising a motor (not shown). The motors of the detector move mechanism 2a, the turn table 3, and the z direction move mechanism 3a and the x direction move mechanism 3b of the turn table 3 are driven and controlled by drive signals supplied from a detector move driver 41, a table rotation driver 42, a table z direction move driver 43, and a table x direction move driver 44, respectively. Each of drivers 41, 42, 43, 44 is controlled by the control section 40. Each pixel data outputted from the CCD camera 22 of the two-dimensional X-ray detector 2 is input to the data processing section 45. The data processing section 45 then performs various processing using the pixel data and performs reconstruction calculation of tomogram. The tomogram provided by the reconstruction calculation or the fluoroscopic image of the target object W is displayed on a display 46. An operation section 47 of a keyboard, switches, and the like is connected to the control section 40. The operator can give various commands and enter various settings as described later by operating the operation section 47. FIG. 2 is a flowchart to show a processing procedure according to the embodiment of the invention. To begin with, while seeing the X-ray fluoroscopic image on the display 46, the operator operates the operation section 47 to move the two-dimensional X-ray detector 2 or the turn table 3 in the x direction through the detector move mechanism 2a or the x direction move mechanism 3b for adjusting the SID and the SOD to determine the imaging magnification and adjust X-ray conditions. At this time, if the imaging magnification is high and the field of view FOV (z) in the vertical direction cannot cover a region that provides the three-dimensional information of the target object W as one imaging procedure is conducted, the operator selects continuous cone CT item. When the operator selects the continuous cone CT item, the operator sets an initial position (in the Z direction) of the turn table 3, a view field FOV (z) in the z direction, a direction when the turn table 3 is moved in the z direction from the initial position, the number of imaging times n, and other conditions to provide tomograms and then gives a start command of the continuous cone CT. The CT apparatus calculates the maximum value of the view field FOV (z) in the z direction based on the x direction positions of the two-dimensional X-ray detector 2 and the turn table 3. The maximum view field FOV (z) in the z direction is displayed on the display 47. Thus, to set the view field FOV (z) in the z direction, the operator can use the maximum view field FOV (z) in the z direction which is displayed on the display 47 or set any desired view field FOV (z) with a narrower width in the z direction, considering distortion, etc., of the two-dimensional X-ray detector 2. In this case, the setup view field FOV (z) in the z direction is always set in a state in which a width from the view field center to one side thereof is equal to a width from the view field center to the other side thereof. Only the pixel data in the range of the setup view field FOV (z) are used to reconstruct the tomogram. When the start command of the continuous CT is given, the turn table 3 is rotated with the turn table 3 set to the initial position and X-ray fluoroscopic data are collected. Upon completion of collecting the data, calculation of reconstruction processing of tomogram is performed and the provided data is retained. Next, when the number of imaging (data collection) times does not reach the setup number of imaging times n, the turn table 3 is moved by the setup view field FOV (z) in the z direction along the z direction in the setup direction, and then X-ray fluoroscopic data are collected. Calculation of reconstruction processing of tomogram is performed using the data, and the provided data is retained. When the number of imaging times reaches the setup number of imaging times n, all data retained so far are concatenated and the resultant data is displayed on the display 46 and the processing is terminated. According to the embodiment of the invention described above, if the imaging magnification is raised to collect high space resolution data and thus the view field FOV (z) in the z direction is narrowed and cannot cover the region which can provide the three-dimensional data of the target object W as one imaging is conducted, the operator simply selects the continuous cone CT item and sets required conditions for performing the continuous cone CT. With such a simple operation, while the turn table 3 is automatically moved in the z direction, X-ray fluoroscopic data can be collected. Therefore, three-dimensional data in a wide region can be provided in a high resolution. In the described embodiment, the invention is applied to the CT apparatus with the X-ray optical axis along the horizontal direction, but can also be applied to the CT apparatus with the X-ray optical axis along the vertical direction, of course. The point is that while the turn table is moved in the direction along the rotation axis of the turn table by the setup view field in the rotation axis direction at a time, X-ray fluoroscopic data can be collected. As described above, according to the invention, the operator simply selects continuous cone CT item and sets the view field in the rotation axis direction of the turn table, the direction when the turn table is moved in the rotation axis direction, and the number of imaging times. Therefore, after one data collection is executed, automatically the turn table is moved in the setup direction by the view field in the rotation axis direction at a time and data collection is repeated. As a result, if the imaging magnification is raised to set a high resolution, a continuous tomogram over a wide region can be provided and three-dimensional information of a comparatively large target object can be provided in a high space resolution. Further, as the number of consecutive imaging times is increased, the limit on the field of view in the rotation axis direction of the turn table can be substantially eliminated.