X-ray computed tomographic apparatus

1. An X-ray computed tomographic apparatus wherein image data are reconstructed on the basis of a plurality of data segments which extend over a plurality of heart beats extracted from data obtained by scanning a patient with X-rays under helical scan, comprising:

a setting device which is configured to set a helical pitch and a rotational speed concerning the helical scan;

a temporal resolution data generation device which is configured to generate a temporal resolution of the image data that correspond to the set helical pitch, the set rotational speed, and a heart rate of the patient;

a screen building device which is configured to build a scan-plan screen that contains the set helical pitch, the set rotational speed, and the generated temporal resolution; and

a display device which displays the scan plan screen.

2. An X-ray computed tomographic apparatus as defined in claim 1 , wherein the scan plan screen contains a graph which expresses a temporal change of the temporal resolution versus a temporal change of the heart rate of the patient.

3. An X-ray computed tomographic apparatus as defined in claim 1 , wherein the scan plan screen contains a temporal change of the heart rate of the patient.

4. An X-ray computed tomographic apparatus as defined in claim 1 , wherein the scan plan screen contains a button for obtaining the heart rate of the patient.

5. An X-ray computed tomographic apparatus as defined in claim 1 , wherein the scan plan screen contains a box for inputting the heart rate of the patient.

6. An X-ray computed tomographic apparatus as defined in claim 1 , wherein the heart rate is a mean heart rate or a median within a predetermined period.

7. An X-ray computed tomographic apparatus wherein image data are reconstructed on the basis of a plurality of data segments which extend over a plurality of heart beats extracted from data obtained by scanning a patient with X-rays under helical scan, comprising:

a selection device which is configured to select a combination in which a temporal resolution of the image data corresponding to a heart rate of the patient becomes the shortest, from among a plurality of combinations of helical pitches and rotational speeds concerning the helical scan as satisfy an upper limit of a scan time;

a screen building device which is configured to build a scan plan screen that contains the selected combination of the helical pitch and the rotational speed, and the shortest temporal resolution; and

a display device which displays the scan plan screen,

wherein the scan plan screen contains a graph which expresses a temporal change of the temporal resolution versus a temporal chance of the heart rate of the patient.

8. An X-ray computed tomographic apparatus as defined in claim 7 , wherein the scan plan screen contains a temporal change of the heart rate of the patient.

9. An X-ray computed tomographic apparatus as defined in claim 7 , wherein the heart rate is a mean heart rate or a median within a predetermined period.

10. An X-ray computed tomographic apparatus as defined in claim 7 , wherein the selection device selects from among the plurality of combinations, a combination in which a temporal average concerning a temporal change of the temporal resolution corresponding to a temporal change of the heart rate within a scheduled breath-hold time period becomes the shortest.

11. An X-ray computed tomographic apparatus as defined in claim 10 , wherein the temporal average is a simple temporal average.

12. An X-ray computed tomographic apparatus as defined in claim 10 , wherein the temporal average is a weighted temporal average.

13. An X-ray computed tomographic apparatus wherein image data are reconstructed on the basis of a plurality of data segments which extend over a plurality of heart beats extracted from data obtained by scanning a patient with X-rays under helical scan, comprising:

a generation device which is configured to generate on the basis of a heart rate of the patient, a plurality of temporal resolutions which correspond respectively to a plurality of combinations of helical pitches and rotational speeds concerning the helical scan as satisfy an upper limit of a scan time;

a screen building device which is configured to build a scan plan screen that contains the plurality of combinations of the helical pitches and the rotational speeds, and the plurality of generated temporal resolution; and

a display device which displays the scan plan screen.

14. An X-ray computed tomographic apparatus as defined in claim 13 , wherein the scan plan screen contains a graph which expresses a temporal change of the temporal resolution versus a temporal change of the heart rate of the patient.

15. An X-ray computed tomographic apparatus as defined in claim 13 , wherein the scan plan screen contains a temporal change of the heart rate of the patient.

16. An X-ray computed tomographic apparatus as defined in claim 13 , wherein the heart rate is a mean heart rate or a median within a predetermined period.

17. An X-ray computed tomographic apparatus as defined in claim 13 , wherein the generation device generates a temporal average concerning a temporal change of the temporal resolution corresponding to a temporal change of the heart rate within a scheduled breath-hold time period.

18. An X-ray computed tomographic apparatus as defined-in- claim 17 , wherein the temporal average is a simple temporal average.

19. An X-ray computed tomographic apparatus as defined in claim 17 , wherein the temporal average is a weighted temporal average.