Abstract: An object of the present invention is to calculate a more accurate beam-hardening correction coefficient. A phantom having an oblong section or a phantom having an annular (sector) section and a uniform thickness is positioned in an X-ray CT system, and scanned from plural directions in order to acquire a plurality of views. The results of the scan are used to calculate a correction coefficient that is used to correct projection information to be acquired from a subject.

Abstract: For the purpose of providing a beam hardening post-processing method that can improve the accuracy of channel-by-channel correction on a BH effect easily and yet taking a non-linear effect into account, phantoms of different diameters are disposed at a position offset from an imaging center to acquire projection information having a transmission length of an X-ray beam varying from view to view (Step S501), hence, acquire projection information having a projection information value varying from view to view, for each channel, correction factors are determined (Step S506), and a corrective function containing even a non-linear effect is determined by higher-order function fitting from the correction factors (Step S508); and therefore, correction with high accuracy can be achieved in the channel-by-channel correction on the projection information values conducted after BH correction, and moreover, correction with high accuracy can be achieved using a smaller amount of phantom projection information, thus reduci

Abstract: For the purpose of determining an offset of the position of an X-ray tube from a prespecified position, and correcting axially projected data D1 and pixel projection data D2 based on the determined offset, proper axially projected data D1 can be obtained by an X-ray focal spot 2102 and a detector 2103 by determining axially projected data D1 at a point 2104 using projection data D0 obtained by a channel that detects an X-ray emitted from the X-ray focal spot 2102 and passing through the point 2104, and shifting the determined axially projected data D1 by a distance DIS1 in the (+)-direction of the x-axis. On the other hand, taking an example of y=Ye/2 (y=r1−r2), and when determining proper pixel projection data D2 at y=r1−r2 by the X-ray focal spot 2102 and the detector 2103, offset correction processing which shifts pixel projection data D2 at a point 2106 in the (+)-direction of the x-axis by a distance DIS2 between points 2106 an 2107 (i.e.

Abstract: In order to control a collimator so that an X-ray impingement position on an X-ray detector is kept constant, an error of the impingement position of a fan-shaped beam (400) in the direction of side-by-side arrangement of a plurality of detector element rows in a detector element array (24) is detected (101), and the collimator is controlled (103) based on the detected error so that the impingement position of the fan-shaped beam is kept at a constant position.

Abstract: In order to eliminate the adverse effect of the partial volume in producing an addition tomographic image by adding a plurality of tomographic images having different slice thicknesses, an offset correction and a sensitivity correction are applied to row data Ij (j=1-J) from which respective tomographic images Gj can be reconstructed; addition data K is generated by performing a weighted addition on the row data Ij with a weight Tj/&Sgr;Tj corresponding to the slice thickness Tj; logarithm processing is applied to the addition data K; and then the addition data is subjected to reconstruction to produce an addition tomographic image G.

Abstract: In order to detect whether the center position of a subject is offset from a scan center and notify a human operator of the result of the detection, the subject center position is detected based on a projection profile of a parallel view at a view angle of 90° (S5). If the distance between the subject center position and the scan center exceeds a predefined range (e.g., 50 cm) (S6), a warning is displayed on a CRT to prompt the operator to adjust the position of the subject and repeat imaging (S7).

Abstract: For the purpose of reconstructing a plurality of X-ray tomographic images having a plurality of practical slice thicknesses while reducing the number of X-ray detector arrays and simplifying configuration, X-rays generated by an X-ray tube 4 are emitted via a slit 15 of a collimator 6 toward a detector 8 disposed opposite to the X-ray tube 4; the length (width) of the collimator 6's slit 15 in the D1 direction and the position of the collimator 6 in the D1 direction are adjustable; the detector 8 is comprised of four X-ray detector arrays; and the widths of the two outer X-ray detector arrays in the D1 direction are larger than the widths of the two center X-ray detector arrays.

Abstract: In order to control a collimator so that an X-ray impingement position on an X-ray detector is kept constant, an error of the impingement position of a fan-shaped beam (400) in the direction of side-by-side arrangement of a plurality of detector element rows in a detector element array (24) is detected (101), and the collimator is controlled (103) based on the detected error so that the impingement position of the fan-shaped beam is kept at a constant position.

Abstract: In order to eliminate the adverse effect of the partial volume in producing an addition tomographic image by adding a plurality of tomographic images having different slice thicknesses, an offset correction and a sensitivity correction are applied to row data Ij (j=1−J) from which respective tomographic images Gj can be reconstructed; addition data K is generated by performing a weighted addition on the row data Ij with a weight Tj/&Sgr;Tj corresponding to the slice thickness Tj; logarithm processing is applied to the addition data K; and then the addition data is subjected to reconstruction to produce an addition tomographic image G.

Abstract: In order to allow slice thicknesses to be set for a twin asymmetric scan in which a scan is performed with a first slice thickness in a first detector row of a multi detector and with a second slice thickness different than the first slice thickness in a second detector row, first, a position of an X-ray beam is moved and a scan is performed while keeping the width of the X-ray beam fixed at twice the first slice thickness to move the position of the X-ray beam to a position at which count values for the first and second detector rows match (ST2-ST5). The count value for the detector row at this time is stored (ST6). Next, the position of the X-ray beam is moved and a scan is performed while keeping the width of the X-ray beam fixed at the sum of the first and second slice thicknesses to move the position of the X-ray beam to a position at which the count value for the first detector row matches the stored count value (ST7-ST9).

Abstract: In order to make an X-ray impinging position coincide with a fixed position from the beginning of a scan, in scanning a subject to be examined by an X-ray emitting/detecting apparatus, an X-ray focus position is predicted based on the temperature of an X-ray tube 20 prior to beginning the scan and scan conditions intended to be currently used, and the position of a collimator 22 or an X-ray detector 24 is adjusted so that the X-ray impinges upon a fixed position on the X-ray detector 24.

Abstract: In order to detect whether the center position of a subject is offset from a scan center and notify a human operator of the result of the detection, the subject center position is detected based on a projection profile of a parallel view at a view angle of 90° (S5). If the distance between the subject center position and the scan center exceeds a predefined range (e.g., 50 cm) (S6), a warning is displayed on a CRT to prompt the operator to adjust the position of the subject and repeat imaging (S7).

Abstract: For the purpose of reconstructing a plurality of X-ray tomographic images having a plurality of practical slice thicknesses while reducing the number of X-ray detector arrays and simplifying configuration, X-rays generated by an X-ray tube 4 are emitted via a slit 15 of a collimator 6 toward a detector 8 disposed opposite to the X-ray tube 4; the length (width) of the collimator 6's slit 15 in the D1 direction and the position of the collimator 6 in the D1 direction are adjustable; the detector 8 is comprised of four X-ray detector arrays; and the widths of the two outer X-ray detector arrays in the D1 direction are larger than the widths of the two center X-ray detector arrays.