Patent ID: 7558365

Claim:
A method of operating an X-ray CT apparatus, said method comprising: performing a scout scan on a subject to obtain scout scan data; selecting a length of an area to be scanned according to the scout scan data; analyzing the length of the area to be scanned to determine a position having a maximum noise index value and a position having a minimum noise index value; substituting a maximum tube current value and a minimum tube current value that can be provided by a present scan of the X-ray CT apparatus into a tube current control model of the X-ray CT apparatus to calculate a first range of noise index corresponding to the position with minimum noise index and a second range of noise index corresponding to the position with the maximum noise index; determining if an intersection exists between the first range of noise index and the second range of noise index; if such an intersection does not exist, ending the present scan of the X-ray CT apparatus; and if such an intersection exists, selecting a combination of a range of tube current value and a third range of noise index within the intersection to perform a subsequent scan.