Cracking, in petroleum refining, the process by which heavy hydrocarbon molecules are broken up into lighter molecules by means of heat and usually pressure and sometimes catalysts. Cracking is the most important process for the commercial production of gasoline and diesel fuel. 1  Cracking of petroleum yields light oils (corresponding to gasoline), middle-range oils used in diesel fuel, residual heavy oils, a solid carbonaceous product known as coke, and such gases as methane, ethane, ethylene, propane, propylene, and butylene.
Cholangiography is the imaging of the bile duct (also known as the biliary tree) by x-rays. percutaneous transhepatic cholangiography (PTC): Examination of liver and bile ducts by x-rays. This is accomplished by the insertion of a thin needle into the liver carrying a contrast medium to help to see blockage in liver and bile ducts.
CT angiography is a type of medical exam that combines a CT scan with an injection of a contrast media to produce pictures of blood vessels and tissues in a part of your body.The contrast is injected through an intravenous (IV) line started in your arm or hand.o evaluate a tumor that is fed by blood vessels. Information from CT angiography may help prevent a stroke or a heart attack. This type of test may also help your doctor plan cancer treatment or prepare you for a kidney transplant. Your doctor may have other reasons for ordering this test.