| 摘要 |
There is provided an X-ray CT apparatus that can control an irradiation X-ray dose in accordance with a displacement of an internal organ due to breathing of an examinee or the like with satisfying both of enhancement of image quality and lessening of exposed dose. In preparation processing before scan is started, an X-ray CT apparatus 1 generates a three-dimensional cross-section model from scanogram projection data of an examinee. An operator is made to input a site of interest, an assumed displacement amount of the site and a desired image quality index value. A scan planning unit 405d calculates an X-ray attenuation index from the three-dimensional cross-section model, and corrects the calculated X-ray attenuation index on the basis of the input site of interest, assumed displacement amount and image quality index value. The scan planning unit 405d further determines a tube current modulating pattern (irradiation X-ray dose modulating pattern) on the basis of the corrected X-ray attenuation index. When scanning is executed, an X-ray tube is controlled according to the determined irradiation X-ray dose modulating pattern, and controlled so as to obtain an optimum X-ray dose.
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