Patent ID: 8054936

Claim:
A xenon CT apparatus comprising: a gas supply device for supplying xenon gas to a subject; an X-ray CT apparatus main body for acquiring CT image data of a test region, for thereby obtaining a xenon concentration (hereinafter, referred to as a test region xenon concentration) C(t) (where t is a time variable) of the test region of the subject; and a data processor for determining the test region xenon concentration C(t) based on the CT image data, together with determining a blood flow f of the test region based on the test region xenon concentration C(t), wherein, in a case where a rate constant (hereinafter referred to as arterial blood rate constant) Ka of the xenon concentration of blood flowing within an artery of the subject (hereinafter referred to as arterial xenon concentration) Ca(t) is determined from a time-course change in the test region xenon concentration C(t), the data processor comprises: a parameter determining means for determining a rate constant (hereinafter referred to as a test region rate constant) K, the arterial blood rate constant Ka, and a xenon partition coefficient λ of the test region xenon concentration C(t) when an average (hereinafter referred to as an error mean square) EMS of the square d 2 of an error d is minimized, the error d being defined as the difference between a change (hereinafter referred to as a ΔCT value) in the CT value of the CT image data corresponding to a time-course change in the test region xenon concentration C(t) and an approximate curve of the ΔCT values; and a blood flow calculating means for determining a blood flow f of the test region using the test region rate constant K and the xenon partition coefficient λ as determined by the parameter determining means.