Cardiac CT system

A cardiac gated spiral CT scanner comprising:

• a source of penetrating radiation and an examination region having a central axis extending in a z direction, said source emitting a beam of radiation that passes through the examination region as the source follows a spiral path relative to a subject positioned within the examination region;
• radiation detectors arranged to receive radiation emitted from the source after it has traversed the examination region;
• an electrocardiogram monitor which acquires electrocardiogram data from the subject, said electrocardiogram data being used to accurately correlate phases of the subject's heart with data collected by the radiation detectors;
• an image reconstruction processor which reconstructs image representations of the subject based on data received from the radiation detectors and ECG monitor;
• a human viewable display which selectively displays the image representations;
• and,
• a control processor which implements a subject-specific scan protocol in response to measured subject characteristics and scanner characteristics;
• wherein the measured subject characteristics include one or more of those selected from a group consisting of average subject heart rate, subject breath hold time, and range of scan coverage in the z direction based on subject anatomy;
• and,
• wherein the control processor accesses a look up table in response to the measured subject characteristics and scanner characteristics, said look up table containing scan protocols.

A cardiac gated spiral CT scanner comprising:

• a source of penetrating radiation and an examination region having a central axis extending in a z direction, said source emitting a beam of radiation that passes through the examination region as the source follows a spiral path relative to a patient positioned within the examination region;
• radiation detectors arranged to receive radiation emitted from the source after it has traversed the examination region;
• an electrocardiogram monitor which acquires electrocardiogram data from the patient, said electrocardiogram data being used to accurately correlate phases, of the patient's heart with data collected by the radiation detectors;
• an image reconstruction processor which reconstructs image representations of the patient based on data received from the radiation detectors and ECG monitor;
• a human viewable display which selectively displays the image representations;
• and,
• a control processor which implements a patient-specific scan protocol in response to measured patient characteristics and scanner characteristics;
• wherein the measured patient characteristics include one or more of those selected from a group consisting of average patient heart rate, patient breath hold time, and range of scan coverage in the z direction based on patient anatomy;
• and,
• wherein the scan protocol selected sets a pitch for the spiral path followed and sets an image slice thickness, such that (i) the patient's average heart rate, (ii) the patient's breath hold time, and (iii) a range of scan coverage in the z direction are accommodated while ensuring that neighboring image slices are at least contiguous in the z direction.

A method of cardiac gated spiral CT imaging comprising:

• (a) assessing a breath hold time for a patient;
• (b) measuring an average heart rate of the patient;
• (c) determining a range of scan coverage;
• (d) based on results from steps (a) through (c), selecting a patient-specific scan protocol;
• (e) in accordance with the selected scan protocol, performing a spiral CT scan of the patient while collecting electrocardiogram data from the patient;
• (f) using the electrocardiogram data to correlate phases of the patient's heart with x-ray data collected via the spiral CT scan;
• and,
• (g) reconstructing from the x-ray data collected an image representation of a region of interest of the patient at a point in time corresponding to a selected phase of the patient's heart.

In a cardiac gated spiral CT scanner including a stationary gantry portion defining an examination region having a central axis extending in a z direction;

• a rotating gantry portion arranged on the stationary gantry portion for rotation about the examination region;
• a source of penetrating radiation arranged on the rotating gantry portion for rotation therewith, said source emitting a beam of radiation that passes through the examination region as the source rotates;
• a patient support which holds a patient being examined at least partially within the examination region and translates the patient through the examination region in the z direction while the source is rotated such that the source follows a helical path relative to the patient;
• radiation detectors arranged to receive radiation emitted from the source after it has traversed the examination region;
• an electrocardiogram monitor which acquires electrocardiogram data from the patient, said electrocardiogram data being used to accurately correlate phases of the patient's heart with data collected by the radiation detectors;
• an image reconstruction processor which reconstructs image representations of the patient based on data received from the radiation detectors;
• and, a human viewable display which selectively displays the image representations;
• a scan control system comprising:
• a control processor which implements patient-specific scan protocols in response to the patient's average heart rate, scan coverage in the z direction, and the patient's breath hold time.