| 摘要 |
PURPOSE:To decrease artifacts without lowering spatial resolution by providing a means which increases the number of translation data before and behind a rotational position where translation data is obtained when the translation data has the sudden change part of transmission data. CONSTITUTION:A CT scanner 10 makes a scan at intervals of DELTAtheta deg. while a radiation source 1 and a detector group 12 are put in the same position relation mutually. Transmission data from the detector group 12 are gathered by a data gathering device 13 and a logarithmic converter 14 calculates a logarithmic conversion value P(t,theta) of I/I0 (I: transmission data, I0: X-ray intensity of the radiation source) from a specific expression. This value P(t,theta) is differentiated by a spatial differentiating device 15. A comparator 16 compares a threshold level Pt with a differential coefficient obtained by the device 15. A rotation control mechanism 17 receives the signal from the comparator 16 and gathers the transmission data at a predetermined angle pitch DELTAdelta(DELTAdelta<DELTAtheta). An image reconstitution computing element 18 decreases the weight of the transmission data of a part which is scanned at DELTAdelta to reconstitute an image. |
