Overview


Computed tomography (CT) scan is an imaging approach that is used to take a series of x-rays from many angles to create cross-sections of the body. The difference in view from a CT scan is comparable to that of looking at slices of a bread loaf, instead of the loaf itself. CT scans are generally noninvasive and may be used for a variety reasons: diagnostics, treatment planning, intervention and many more. It is generally performed on a outpatient basis. The settings in which this procedure is carried out may have an effect on the cost. It usually costs less when it is done on outpatient basis than when it is done in the hospital settings. This allows the CT scan site to specialize in these kinds of services to offer them at a cheaper cost to patients. CT is a very important and useful tool that helps physicians to discover abnormalities, such as tumors and others. It also helps them to evaluate the effectiveness of therapy. For instance, in the case of a cancer that is being treated, it helps providers to look at before and after images of the area where the cancer was developed.

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A CT Scan machine with its cover removed

Applications:
When the CT scan produces its cross-sections, the medical personnel can view these sections individually to examine particular parts of the body, or they can be processed together to create additional 3D visualizations for use in more broad examinations or specific perspectives. A doctor could use the specific cross-section to examine the fibers of a tendon, or he could use the combined generated visualization to observe how moving a muscle on that limb affects that particular tendon. A CT scan could also be scheduled to diagnose muscle/bone conditions (tumors, fractures, etc.), or to pinpoint exactly where one of them might be found. CT scans also guide procedures like surgery, biopsy, and radiation therapy, based on information found in the CT scan before these procedures were started. Use of the scan can also be applied to tracking growth and movement of conditions and diseases, such as cancer, heart disease, and liver masses. Internal injuries that couldn't otherwise be observed can include internal bleeding and others.

How is the test performed?
The CT Scan machine is a big instrument that multiple parts. It has moving table on which the client is asked to lie down still which the different X-rays beams are going through the body, usually in a spiral manner. Lying down is really important because similarly to picture that we everyday with our phones, cameras and other devices, those picture with machine can be blurred with movements. Positing may vary depending of the body parts that is being examined and the type of equipment being used. Image data obtained during the scan are sent to and saved on a computer. Healthcare professionals take advantage of computers' ability to identify significantly more shades of gray than the human eyes. Printed on a monitor, the computer identify areas where there are unexpected shades on the scan. After the technician is done placing the patient correctly on the machine, he or she leaves the room to operate the machine from another room. This is done to reduce the technician exposure to radiations.


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Image of client about to undergo a CT Scan

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How to prepare for the test?
Depending on the part of the body being examined, a contrast (dye) may be used for certain areas of body are seen better with the use of a contrast. This is true for many of the internal organs. The route of administration of the contrast depends on the body parts to be scanned. It may be administered intravenously, rectally, and orally. It is important the client let the physician know if he or she has had any allergic reaction to contrast in the past. Also, if he or she is allergic to shellfish. Patients on metformin may be asked to stop taking the medication before the procedure, for the use of a dye may alter with the body mechanism of clearing metformin out of one's system. Also, the patient may be asked to increase their fluids intake to flush the dye out of the body. It's also important that the patient remove all jewelry, for the machine uses magnets. A hospital gown may be worn during the test. It is suggested to stop eating hours before the scan to reduce the chance that digestion will distort the imaging process. If the recipient of the scan is an infant or toddler, it's recommended to use a sedative to keep them calm and still.


Benefits and Risks
Similar to that of any other procedure or treatment, CT Scan comes with many benefits as well as risks. With the appropriate use of this procedure, the benefits outweigh the risks. CT Scan can help avoid the need for certain surgeries performed for diagnostic purposes. As mentioned above, the use CT Scan can help discover many diseases in their early stage, and also help monitor the efficacy of certain treatments, such as cancer treatment for example. However, there are many risks associated with the use of this procedure. Use of a contrast material as suggested by your doctor can sometimes cause medical problems and allergic reactions. In most cases they are mild and result in rashes, however some severe cases have been reported as life-threatening, including a response called anaphylaxis. The most common contrast contains Iodine. If you're allergic to Iodine, you may experience nausea, vomiting, sneezing, itching, or hives. If you're allergic and still must take the contrast, use of an antihistamine can mitigate the effects of your allergy if taken before the procedure. Also consuming liquids frequently will help to filter the Iodine out of your kidneys, especially if you suffer from diabetes or kidney disease. Exposure to the increased radiation associated with CT scans as compared to normal X-rays carries an increased risk of developing cancer. This marginal difference in radiation between CT scans and X-rays is very small, although it is still worth noting due to the sensitive nature of radiation and cancer. If the patient is pregnant, another type of exam such as an ultrasound or MRI is suggested to avoid the risk of exposing the fetus to radiation. The physician should weigh the benefits and risks before ordering the procedure.



Video:
https://www.youtube.com/watch?v=raeZulSQC5g

Related Terms:
CAT Scan
Computed axial tomography scan
Abdominal CT Scan
Cranial CT Scan
Orbit CT Scan
Lumbosacral Spine CT Scan
Thoracic CT Scan

Web Resources:
http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/MedicalImaging/MedicalX-Rays/ucm115317.htm
http://www.webmd.com/a-to-z-guides/computed-tomography-ct-scan-of-the-body
References:
http://www.nlm.nih.gov/medlineplus/ency/article/003330.htm
http://www.mayoclinic.org/tests-procedures/ct-scan/basics/definition/prc-20014610