CT scan working

Inside the CT scanner is a rotating gantry that has an x-ray tube mounted on one side and an arc-shaped detector mounted on the opposite side. An x-ray beam is emitted in a fan shape as the rotating frame spins the x-ray tube and detector around the patient. Each time the x-ray tube and detector make a 360-degree rotation and the x-ray passes through the patient's body, the image of a thin section is acquired. During each rotation the detector records about 1,000 images (profiles) of the expanded x-ray beam. A dedicated computer into a two-dimensional image of the section that was scanned then reconstructs each profile. Multiple computers are typically used to control the entire CT system.
When computer reassembles the image slices, the result is a very detailed, multidimensional view of the body's interior.
A relatively new technique, spiral (helical) CT has improved the accuracy of CT for many diseases. A new vascular imaging technique, called spiral CT-Angiography is non-invasive and less expensive than conventional angiography and allows doctors to see blood vessels without the need for more invasive procedures.
The term "spiral CT" comes from the shape of the path taken by the x-ray beam during scanning. The examination table advances at a constant rate through the scanner gantry while the x-ray tube rotates continuously around the patient, tracing a spiral path through the patient. This spiral path gathers continuous data with no gaps between images.With spiral CT, refinements in detector technology support faster, higher-quality image acquisition with less radiation exposure. The current spiral CT scans are called multidetector CT and are most commonly four- or 16-slice systems. CT scanners with 64 detectors are now available. These instruments should provide either faster scanning or higher resolution images. Using 16-slice scanner systems the radiologist can acquire 32 image slices per second. A spiral scan can usually be obtained during a single breath hold. This allows scanning of the chest or abdomen in 10 seconds or less. Such speed is beneficial in all patients but especially in elderly, pediatric or critically ill patients, populations in whom the length of scanning was often problematic. The multidetector CT also allows applications like CT angiography to be more successful

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