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• X ray images – shadow pictures are formed when an object is placed between the x ray and photographic film. The dense part like bones absorb the rays whereas soft parts like tissue let rays pass through.
• Digital subtraction angiography – contrast media matches with x ray energy. Increases absorption ability of x ray. When inserted into blood vessels, this shows the blood vessels clearly on the xray due to it absorbing the rays.
• DSA - Normal x ray picture is taken. Another x ray picture with the media is taken. One picture with the anatomy is digitally subtracted from the other to just reveal the blood vessels.
• CT (computerized tomography) – object structure reconstructed by collecting all the x ray images taken from around the object.
• CT formation - Computer forms a 3D array. Each array is related to a specific part of the body. Each array has a number that shows the amount of X ray absorption. This is then collected by the computer. Each number has color assigned to it and an image is constructed.
• Choice of colour is important for image quality.
• CT projections – modern CT machine can form multiple 2D images to combine it and form a detailed 3D image. During a CT scan the x ray source and detectors move around the patient in a circular pattern or the patient moves in a spiral motion.

  Outside CT the CT settings are controlled.
• In computer assisted surgery CT forms 3D images using fast microprocessors.