| 摘要 |
<p>PROBLEM TO BE SOLVED: To fix an S/N ratio in an image at any position by suppressing a change in the S/N ratio which occurs in spiral photographing with an X-ray irradiation amount adjusting function and depends on an image re-constituting position in an X-ray CT apparatus. SOLUTION: An X-ray irradiation control part 59 in a whole control part 13 controls the X-ray irradiation amount of an X-ray tube 15 in response to the form of a subject 16. Spiral projection data of X-rays passing through the subject 16 by an X-ray detector 17 is transmitted to a pre-processing part 21. The obtained spiral projection data is corrected by a contribution rate control means 26 in the pre-processing part 21. The pattern control part 25 of the whole control part 13 makes a timing in the pattern of a change in the X-ray irradiation amount by the X-ray irradiation control part 59 to coincide with a timing in the pattern of the change in the contribution rate of spiral projection data by the spiral projection data contribution rate control means 26.</p> |
