| 摘要 |
For the purpose of reducing exposure of a subject to unnecessary radiation by controlling the tube current according to the X-ray emitting direction with respect to a region to be examined in the subject, a transmission area S is calculated from a cross-sectional plane (S801) and an ellipticity R is calculated for the cross-sectional plane (S802, S803). An image SD of a region having the transmission area S is then calculated (S804), and a SD ratio of a region having the ellipticity R is calculated (S805). An image SD of a region having the transmission area S and ellipticity R is then calculated using the image SD and the SD ratio (S806). Next, a target SD is specified (S807), and the tube current that controls X-rays emitted in the major-axis direction in the cross-sectional plane of the subject is calculated using the image SD obtained at S806 and the target SD (S808), and the tube current that controls X-rays emitted in the minor-axis direction in the cross-sectional plane of the subject is calculated using the obtained tube current and R (S809).
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