Abstract: In an X-ray CT apparatus for sequentially performing first and second scans of different control parameters by switching the control parameter of at least one of tube voltage and tube current of an X-ray tube on the same slice in a subject, the time interval between the first and second scans is shortened. A scan controller for performing a control on a whole scan starts transmitting the control parameter corresponding to the second scan to an X-ray controller for controlling the tube voltage and the tube current in an X-ray tube during the first scan without waiting for the end of the first scan (S27).

Abstract: In an X-ray CT apparatus for sequentially performing first and second scans of different control parameters by switching the control parameter of at least one of tube voltage and tube current of an X-ray tube on the same slice in a subject, the time interval between the first and second scans is shortened. A scan controller for performing a control on a whole scan starts transmitting the control parameter corresponding to the second scan to an X-ray controller for controlling the tube voltage and the tube current in an X-ray tube during the first scan without waiting for the end of the first scan (S27).

Abstract: A method for determining the heating time constant of a cathode of an X-ray tube. The value of a boost current applied during a preliminary period must be a function of both a pre-existing heating holding current and a service current to be used subsequently. A model of evolution of cathode temperature produces a minimizing tube current error between a tube current that is expected for the tube and a tube current obtained. The model requires only four parameters that need to be computed.

Abstract: To adjust the emission rate of radiation from an X-ray tube, the value of the current of the X-ray tube is modeled empirically by a second-order polynomial function depending on the heating current and a first-order polynomial function depending on the high voltage. A transfer function gives precision closer than 3% for the adjusting of an expected tube current. This function can also be used to take account of disparities of manufacture and of the aging of the tubes in use.

Abstract: To adjust the emission rate of radiation from an X-ray tube, the value of the current of the X-ray tube is modeled empirically by a second-order polynomial function depending on the heating current and a first-order polynomial function depending on the high voltage. A transfer function gives precision closer than 3% for the adjusting of an expected tube current. This function can also be used to take account of disparities of manufacture and of the aging of the tubes in use.

Abstract: A method for determining the heating time constant of a cathode of an X-ray tube. The value of a boost current applied during a preliminary period must be a function of both a pre-existing heating holding current and a service current to be used subsequently. A model of evolution of cathode temperature produces a minimizing tube current error between a tube current that is expected for the tube and a tube current obtained. The model requires only four parameters that need to be computed.