The Common Vein Copyright 2009

Main risk is contrast allergy – usually mild – rash itchiness and hives

Ionizing radiation. More radiation than a standard X-ray

Typical values for the effective dose for patients undergoing chest CT examinations are about 5 mSv.

Patient doses may be lower if high-resolution CT is performed using thin sections, or higher if both unenhanced and contrast-enhanced images are generated. 

Cost.