Heavy metals such as cadmium, lead and mercury are common air pollutants. and are emitted (predominantly into the air) as a result of various industrial ac-. tivities. This report reviews the available information on the sources, chemical. properties and spatial distribution of pollution by cadmium, lead and mercury.
Assuming that you are already inside the CT scanner ready to get scanned. CT scan without contrast (head, sinus, orbits, abdomen, pelvis, cervical, thoracic, lumbar and dental scans) take approximately 15 minutes. CT studies with contrast of the chest, pelvis, head or neck take approximately 30 minutes. Whereas, aortic contrast studies may take up to 45 minutes.
If you will receive contrast before your CT scan: 1  You may be asked not to eat anything for 4 hours before your scan.  You may still drink clear liquids (water, clear juices, and coffee or tea without milk) until your scan.