| Computerized tomography (CT), is a noninvasive diagnostic form of x-ray that makes cross-sectional images (slices), in different planes, of the interior of the body. Unlike the flat films of conventional radiography, the CT scanner circles the body measuring the transmission of x-rays as they pass through body structures, and taking multiple x-rays as it repeats this measurement (called a projection) in many different directions through the same section or slice of the body. When a sufficient number of projections in different directions are measured, the resulting data can create a single, unique arrangement in two- dimensions of the intervening body structure. Adjacent two-dimensional slices can then be reconstructed to produce three-dimensional structures for visualization of abnormalities, or for surgical planning.
A dye-like material (contrast medium) may be injected intravenously to make blood vessels, organs, or abnormalities show up more clearly. Compared to other diagnostic methods (angiography, ventriculography), CT scanning is simple, quick, and, because it uses an ultra-thin low-dose x-ray beam, it provides less exposure to radiation; it gives highly detailed visualization of the internal organs and soft tissues, providing a view of an entire area of interest with a single exposure. Spiral CT is advantageous for trauma victims because it minimizes time spent performing the scan.
CT scanning is used for the diagnosis and treatment of head injury or body trauma or to detect tumors or other abnormalities. |
Source: Medical Disability Advisor
| CT scans are indicated to detect or confirm the characteristics, size, and involvement of abnormal structural changes. Wherever the location, a tumor can be evaluated before definitive treatment is begun. A head CT can provide direct information about bruises (contusions) or blood clots (hematomas) within or outside (epidural or subdural hematomas) the brain. CT of the spine is indicated in cases of suspected disc herniation, spinal infection, trauma, or intraspinal tumor. A face or neck CT is indicated for inflammation or infection, fractures of the facial structures, or for assessing foreign bodies within the eye socket (orbit). Chest CTs are most commonly used to detect suspected cancers (malignancies) and to determine the extent to which the cancer has spread (metastasis). CT is used to define the presence and extent of the ballooning of a vessel due to weakness of the vessel wall (traumatic aneurysms) and the splitting of an aortic vessel wall (aortic dissections). High-resolution CT can help evaluate lung diseases and, when used with dye (intravenous contrast), can be used to confirm an inflammation of the pancreas (acute pancreatitis).
CT may also be useful in differentiating a kidney tumor from a faintly calcified stone that may not be visible on plain x-ray. It can also help in the classification of kidney injuries by defining the extent of lacerations, hematomas, or urine leaking into the abdominal cavity. In the pelvis, CT can provide information regarding the extent of tumors in the lymphatic system and their relationship to normal structures. While bone fractures are usually evaluated by standard x-ray, CT scan provides more precise information about the presence, location, orientation, and relationship of fracture fragments in complex anatomic regions such as the pelvis, shoulder, foot, and ankle. CT can provide precise locations and help guide the needle to sample of cells withdrawn through a needle for microscopic examination (aspiration biopsies), to withdraw a core of tissue withdrawn through a large-bore needle, for microscopic examination (core biopsy), for through the skin (percutaneous) drainage of abdominal abscesses, or for other fluid collections. CT can also be used to guide the placement of various catheters or surgical instruments. The CT may not be diagnostically helpful for people who cannot lie still (due to some neurological diseases), for the extremely obese, or for those who have a fear of being surrounded by or contained within a machine (this later would be unusual because of the openness of the scanner).
It's important to note that MRI scanning also creates an image of body structures by combining a series of pictures taken at different levels and angles. However, MRI uses a different technology to create the images. MRIs have replaced CT scans for many soft tissue conditions, but CT continues to be the best imaging test in select situations. |
Source: Medical Disability Advisor
| The individual being scanned must lie still on a padded metal couch that is encircled by the CT scanner. The individual is positioned in the scanner so that the correct part of the body is located in the center of the scanner. Scans are painless, and most take between 10 to 30 minutes. If an intravenous contrast medium is required, a temporary catheter or needle is placed into a vein for injection of that medium. There is usually no need for specific pre-procedure preparation, although some abdominal scans may require that the individual fast for a short period of time. Scans that focus on the bladder require the bladder to be full prior to scanning. |
Source: Medical Disability Advisor
| CT scanning provides highly detailed information, as well as a view of an entire area of interest with a single exposure. |
Source: Medical Disability Advisor
| There is minimal risk of complication from radiation. If a contrast medium is used, there is a risk of allergy to the medium. Because some contrast mediums use an iodine base, individuals who are allergic to iodine or shellfish, which also contain high levels of iodine, need to inform their healthcare providers of this allergy. Because x-rays can be harmful to a developing fetus, pregnant women need to inform their healthcare provider of this condition. |
Source: Medical Disability Advisor
| No work restrictions and accommodations are expected with this procedure. |
Source: Medical Disability Advisor
| Profit, Rex E. "Computed Radiography." Merrill's Atlas of Radiographic Positions and Radiologic Procedures. Eds. Philip W. Ballinger and Eugene D. Frank. St. Louis: Mosby, Inc., 1999. 307-322. |
Source: Medical Disability Advisor
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