A scan plan support apparatus for supporting development of a scan plan for a scan sequence including a plurality of scan elements for X-ray computed tomography, comprising: a scan planning unit adapted to generate data of a scan planning window including a timing chart expressing the scan sequence as a temporal change in a dose index, wherein in the timing chart the plurality of scan elements are arranged based on start times of scan elements in a time direction wherein an abscissa of the timing chart represents time, and an ordinate of the timing chart represents the dose index, so that the timing chart represents the dose index of X-ray scan over time for each scan element; and a display unit for displaying the scan planning window on the basis of the generated data, wherein each scan element is expressed by a graphic pattern (G#1-G#5) that represents a scan mode type and a dose index of X-ray scan, wherein the graphic patterns (G#1-G#5) respectively have frames (f1-f5), which respectively have a width from a start time of the respective scan mode type to the time when a total scan time elapses and a height corresponding to the respective dose index values, and wherein the scan plan support apparatus is configured such that a scan condition for each scan element is changeable by pointing and moving the frames (f1-f5) of the graphic patterns (G#1-G#5) with a pointing device to change the scan start times or the order of the scan elements via first tool buttons for prolonging or shortening a scan time by dragging a first tool button to the left or right while pointing a pointer at the first tool button with the pointing device, and to adjust the magnitude of the dose index by dragging a second tool button in a vertical direction while pointing a pointer at the second tool button with the pointing device, whereby the dose index is re-calculated and displayed in real time according to the adjustment of the dose index, and that the scan plan of the scan sequence expressed in the timing window is provided to a system controller of an X-ray computed tomography apparatus through a data/control bus for performing an examination with the scan sequence of the scan sequence plan. a scan planning unit adapted to generate data of a scan planning window including a timing chart expressing the scan sequence as a temporal change in a dose index, wherein in the timing chart the plurality of scan elements are arranged based on start times of scan elements in a time direction wherein an abscissa of the timing chart represents time, and an ordinate of the timing chart represents the dose index, so that the timing chart represents the dose index of X-ray scan over time for each scan element; and a display unit for displaying the scan planning window on the basis of the generated data, wherein each scan element is expressed by a graphic pattern (G#1-G#5) that represents a scan mode type and a dose index of X-ray scan, wherein the graphic patterns (G#1-G#5) respectively have frames (f1-f5), which respectively have a width from a start time of the respective scan mode type to the time when a total scan time elapses and a height corresponding to the respective dose index values, and wherein the scan plan support apparatus is configured such that a scan condition for each scan element is changeable by pointing and moving the frames (f1-f5) of the graphic patterns (G#1-G#5) with a pointing device to change the scan start times or the order of the scan elements via first tool buttons for prolonging or shortening a scan time by dragging a first tool button to the left or right while pointing a pointer at the first tool button with the pointing device, and to adjust the magnitude of the dose index by dragging a second tool button in a vertical direction while pointing a pointer at the second tool button with the pointing device, whereby the dose index is re-calculated and displayed in real time according to the adjustment of the dose index, and that the scan plan of the scan sequence expressed in the timing window is provided to a system controller of an X-ray computed tomography apparatus through a data/control bus for performing an examination with the scan sequence of the scan sequence plan.