Emission CT apparatus

An emission CT apparatus for detecting, in positions around an examinee, radiation from radioactive nuclides introduced into the examinee and having accumulated in a site of concern, in order to acquire density distribution images (sectional images) of the nuclides in sections of the site of concern, said apparatus comprising:

• two-dimensional radiation detecting means for detecting said radiation;
• rotary means for revolving said two-dimensional radiation detecting means stepwise by predetermined angle increments around said examinee, said detection means stopping at each increment to collect image data for a view;
• data storage means for collecting the image data from said two-dimensional radiation detecting means for a plurality of respective time frames defined by dividing a time during which said detection means is stopped at each increment into the respective time frames;
• computing means for determining a center of gravity of the image data in each of said respective time frames, and for determining a center of gravity of simply added image data obtained by simply adding the image data in the plurality of respective time frames belonging to each view;
• adding means for adding said image data in said respective time frames belonging to each view, thereby generating said simply added image data, said adding means also determining a difference between the center of gravity of said image data in each respective time frame belonging to each view and the center of gravity of said simply added image data, correcting a displacement by moving the image data in said each respective time frame by the difference corresponding to the respective time frame, and adding the image data of corrected time frames, thereby generating corrected image data;
• and
• image reconstruct means for reconstructing an image by using, as projection data, said corrected image data obtained for each view, and back projecting said projection data.