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.
Computerised tomography (CT) has been around since the 1970s. There are two ways in which a CT scan can be used for the heart â one is a CT coronary angiogram and the other is a CT calcium score. A CT scan produces multiple images of the heart from different angles, which the doctor can then see on a computer screen.The images are picked up using detectors.omputerised tomography (CT) has been around since the 1970s. There are two ways in which a CT scan can be used for the heart â one is a CT coronary angiogram and the other is a CT calcium score. A CT scan produces multiple images of the heart from different angles, which the doctor can then see on a computer screen.