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.
A computed tomography (CT) scan is a noninvasive diagnostic test that uses x-rays and a computer to create images of the body. It allows your doctor to view your spine or brain in slices, as if it were sliced layer-by-layer and a picture taken of each slice.ther detailed cross sections can be taken of the brain, vessels of the brain, neck, shoulders, spine, discs, spinal cord, and vessels of the spine. A CT scan can help your doctor diagnose many conditions including: 1  brain damage after a head injury. 2  brain tumors. 3  ruptured or leaking aneurysms.