The computer is included in the mod

The computer is included in the model in (gambar) as part of the operator’s console; various scanners may have a separate cabinet for the computer. As each scan is completed, the data acquisition system (DAS) converts the signal from the detectors into digital data and relays it to the computer. The computer is able to integrate the information from the DAS and reconstruct images almost instatntaneously. Early CT computers could do only one process at a time, which resulted in image reconstruction times from as short as 15 seconds to as long as several minutes, depending on the level of software installed. Advanced CT computers are able to scan the patient, collect the data, reconstruct the image, archive the image, and begin the next scan in about 2 to 5 seconds. The computer’s main disk drive can provide only short-term storage for image; eventually the finished examinations must be archived, or copied, to a long-term storage device so that the patient’s scan be retrieved if necessary.
The computer can also accept a wide variety of software programs, such as three-dimensional (3D) and multiplanar reconstruction, which create different views of patient anatomy from axial image data; bone density of bone in a patient, usually the spine; thea cardiac scanning. Which provides axial images of the heart while intravenous (IV) contrast is being injected. Several CT options are discussed later in the chapter
The types of storage devices most commonly used are magnetic tape, cassette tape, and optical disk. Magnetic tape is a common storage device, but each tape holds a limited number of images. Retrieving images from tape can be a time consuming process and with some CT systems it is not possible to scan patient when images are being retrieved. Images stored on a magnetic tape are typically stored in a 256 matrix to save space and to put as many images as possible on each device. The total number of images stored per tape varies by manufacturer, but an average would be abaout 250 images. Cassette tapes are much faster than magnetic tapes and are capable of archiving up to 2000 images in a 256 matrix, which preserves original image quality. They are relatively inexpensive and their small size makes them easy to store. Optical disk technology has been adapted for CT image archival. The optical disk also archived images data in a 256 matrix and requires very little space for storage, but it is somewhat more expensive. Optical disk can archived up to 9000 images in a 256 matrix, which substantially reduces the number of storage device so that patient examinations can be retrieved when necessary. If the storage devices can be reused, images will be kept for about 1 year before new images are copied over the old ones.