What Is A CT Scan?

A computerized tomography (CT) scan is a diagnostic imaging technique used to produce detailed pictures of the bones, organs, and other tissues. A computed tomography scan can be performed on any part of the body and does not cause pain or discomfort. CT scans provide more detailed pictures of the structures inside of a patient's body than a standard x-ray would. Computerized tomography scans do not produce as much detail as MRI scans, but they are less expensive to perform and used more often than MRI scans. A CT scan uses a large doughnut-shaped machine the patient slides into on a special table. The computerized tomography machine has a much larger opening and is not as deep as an MRI machine, making sedation less necessary for some patients.

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How The Scan Works

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Computerized tomography scans make two-dimensional pictures of a section of a patient's body. This scan uses numerous narrow beams of radiation that are sent through a patient's body in an arc shape. This allows for a collection of x-rays of the body to be taken from different angles. The x-ray apparatus inside of a CT scanner can see hundreds of degrees of tissue density, giving it the ability to form details specific to certain tissues within an organ. The cross-sectional x-rays are compiled and built into a two or three-dimensional representation of the body that is then projected onto a monitor. Computerized tomography scans have improved significantly since their debut in the 1970s. CT scanners can be found in outpatient facilities as well as hospitals. A CT scan can help clarify an abnormality in a patient's body another test has picked up, such as an ultrasound or an x-ray.

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When CT Scans Are Used

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Computerized tomography scans are used to create images of organs and structures inside of a patient's body that most commonly include the pelvis, soft tissues, brain, lungs, bones, abdomen, and blood vessels. These scans are highly preferred to make a clinical diagnosis of several types of cancers, such as lung cancer, liver cancer, and pancreatic cancer. A CT scan can tell a patient's doctor the exact size of a tumor, where it is located concerning other structures, and the extent of which it has affected neighboring tissues. This type of scan can tell a doctor if a patient has any bleeding, tumors, or swollen arteries in their brain. CT scans can be useful when evaluating the condition of a patient's bones, identifying signs of bone disease, state of their spine, and changes in bone density. In some cases, computed tomography scans can be used as a guide for a patient's doctor when they need to do a biopsy or take a tissue sample.

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Preparing For A CT Scan

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The preparation needed for a CT scan can differ depending on what part of an individual's body is being scanned. While metal objects like jewelry, hair clips, zippers, studs, button snaps, and underwires do not pose a safety hazard during a CT scan, they can compromise the quality of the results. Some medications may need to be stopped before the scan because they can interfere with the contrast agent being used. When an individual has a CT scan on their abdomen or pelvis, they may need to consume a contrast drink before the scan so their digestive tract shows up clearly. Someone having a CT scan on their pelvic region may need to have an enema with a contrast substance to help highlight their bowels on the scan. They may be asked to empty their bladder before the scan. A contrast agent may need to be injected into a patient's bloodstream before the scan,

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CT Scans With Contrast

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A contrast medium may be needed in some patients who have a CT scan. A barium based or water-based liquid contrast medium may need to be consumed orally before a patient has a pelvic or abdominal CT scan. If the scan is to be focused on the patient's small intestine, they may need to arrive at least an hour ahead of their scheduled scan. This time is required so the contrast medium has time to reach their small intestine before the CT scan is taken. Some patients need to have an intravenous contrast medium for their CT scan to help highlight the flow of blood through the suspected structure or organ in the body. Intravenous contrast medium is injected into a vein in the patient's arm so it enters into their circulation. The intravenous contrast medium may make patients feel flushed or unusually warm. Some patients may get an upset stomach from the intravenous contrast medium after it is injected.

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Risks Of A CT Scan

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A computerized tomography scan is generally known to be a safe procedure for most individuals. While ionizing radiation is used during a CT scan, the exposure to the patient is minimal and should not have any long term effects. Even though the dose of radiation is low, it can harm an unborn baby, so a pregnant woman or on who thinks they may be pregnant should not have one. Additionally, a patient can have an allergic reaction to the contrast agent used for their computerized tomography scan. Individuals who have a known allergy or sensitivity to iodine, contrast dye, or shellfish should speak to their physician before having a CT scan with contrast. Any patient who has or has previously had problems with their kidney function should notify their doctor before they have a CT scan with contrast, as the contrast medium can induce acute kidney failure.

Whitney Alexandra