Specific Anatomic RegionColon
ApplicationVirtual colonoscopy
AuthorFishman EK
Reference SourcePersonal Communication
Scanner UsedSiemens Plus4 Volume Zoom
KV / mAs / Time per Rotation (sec)120/165/.5
Detector Collimation (mm)1 or 2.5
Slice Thickness (mm)1.25 or 3
Data Reconstruction Interval (mm)1 or 3
Table Speed (mm per rotation) / Pitch6 /6 or 15 / 6
Oral ContrastN/A (rectal air only)
IV Contrast Volume and TypeN/A or IV contrast
Injection RateN/A or 2-3 cc/sec
Scan Delay (sec)N/A or 30 sec
3D Technique UsedMPR and Volume rendering
  • The optimal protocols have not yet been defined. A lower dose study can be done using 120 / 110 / .5 with a pitch of 6 (12 mm / sec travel). Low dose will be important if virtual colonoscopy becomes a screening tool.
  • We like to use IV contrast as it makes it easier to detect the presence of polyps.
  • Prone and supine images are needed in all cases.