What is Ytacan used for?

CT scan

A CT scan is a specialized X-ray test. There can be pretty clear pictures of the inside of your body. In particular, there can be good images of soft tissues of the body that are not visible on ordinary x-rays.

Note: The following information is only a general guide. Precautions and the way tests are done may vary between different hospitals. Always follow the directions given by your doctor or local hospital.

CT scan

  • How is a CT scan done?
  • What is a CT scan used for?
  • What preparations do I have to make before a CT scan?
  • Can someone be with me during the scan?
  • What can I expect after the scan?
  • Are there any possible complications?

How is a CT scan done?

CT stands for computed tomography. It is sometimes called a CAT scan. CAT stands for computer-controlled axial tomography. (Sometimes the word "calculated" is used instead of "computerized".)

The CT scanner looks like a huge thick ring. There is an X-ray source in the wall of the scanner. X-ray detectors are located opposite the X-ray source on the other side of the ring. You lie on a couch that slides into the center of the ring until the body to be scanned is inside the ring. The X-ray machine in the ring rotates around your body. As it rotates, the X-ray machine sends thin X-rays through your body, which are detected by the X-ray detectors.

By NithinRao (Own work) Public domain, via Wikimedia Commons.

The detectors measure the strength of the X-ray beam that has passed through your body. The denser the tissue, the less X-rays will be transmitted. The X-ray detectors feed this information into a computer. Different types of fabric with different densities appear as an image on the computer monitor in different colors or shades of gray. In effect, the computer creates an image of a section (cross section) of a thin section of your body.

As the couch slowly moves through the ring, the x-ray beam passes through the next section of your body. Therefore, several cross-sectional images of the examined body part are recorded by the computer. Newer scanners can even generate three-dimensional images from the data that comes from the various layers of the body part to be scanned.

What is a CT scan used for?

A CT scan can be done on any section of the head or body. There can be clear pictures of bones. It also provides clear images of soft tissues that a regular X-ray test cannot show, such as muscles, organs, large blood vessels, the brain, and nerves. The most common CT scan done is the brain - to determine the cause of a stroke or to assess severe head injuries. Other uses of a CT scan include:

  • Abnormalities in the body, such as tumors, abscesses, abnormal blood vessels, etc., if symptoms are suspected or other tests are carried out.
  • To give a surgeon a clear picture of an area of ​​your body prior to certain types of surgery.
  • To determine the exact location of the tumor before radiotherapy.
  • To help doctors find the right place to take tissue samples (biopsies).

What preparations do I have to make before a CT scan?

Usually very little. It depends on which part of your body you want to scan. The CT department will give you instructions so that the scan can be performed. Typically, you need to remove all metal objects such as jewelry, hair clips, etc. from your body. It is best not to wear clothing with metal zippers, rivets, etc. You may be asked not to eat or drink a few hours before the scan, depending on the area of ​​the body to be scanned. If you need a contrast injection as described below, you may need to stop certain medicines before the procedure. This may apply to people taking metformin, a medicine used to treat diabetes. If you are taking this medication, your doctor should give you instructions on what to do.

In some situations, depending on the part of the body that is being scanned, one of the following steps may be required. These aim to block a certain amount of X-rays that go through different tissues. This helps to get a better contrast between different organs and tissues on the scan images.

  • For abdominal and pelvic scans, you can have a special drink before the scan. This helps to show the stomach and intestines better.
  • During pelvic scans, some fluid can get into the back passage (rectum).
  • For pelvic scans, women may be asked to insert a tampon into the vagina.
  • Sometimes a dye (contrast medium) is injected into the bloodstream through a vein in your arm. The dye can make you feel reddened and have a strange taste in your mouth that will soon wear off.

The CT scan itself is painless. You cannot see or feel any x-rays. You are asked to be as calm as possible, otherwise the scanned images will be blurry. Traditional CT scans can take anywhere from 5 to 30 minutes, depending on which part of the body (or parts) is being scanned. More modern CT scans (helical CT scans) take less than a minute and also require less radiation.

Can someone be with me during the scan?

Because the scan uses X-rays, other people should not be in the same room. The operator controls the movement of the bed and the scanner from a screen or in a separate control room. (This protects them from repeated X-rays.) However, you can usually talk to them on an intercom and you will be watched on a monitor at all times.

Some people feel a little anxious or claustrophobic in the scanner room when they are alone. If you are particularly anxious, a mild sedative may be offered.

What can I expect after the scan?

You can return to your normal activities once the scan is complete. However, if you had a sedative for the scan, you will need someone to escort you home. You cannot drive until the sedative has worn off.

The images from the scan are examined by an X-ray doctor (radiologist) who sends a report to the doctor who requested the scan.

Are there any possible complications?

Complications are rare. Some people rarely have an allergic reaction to the dye (contrast agent) that is sometimes used. This can be dealt with immediately. Very rarely, the dye can cause some kidney damage, most common in people who are already known to have kidney problems.

Pregnant woman

If possible, pregnant women should not have a CT scan, as there is a risk of X-rays having a noticeable effect on the unborn child.

Risks of X-rays in CT examinations

CT scans use X-rays, a type of radiation. Exposure to large doses of radiation is related to the development of cancer or leukemia, often many years later.

The dose of x-ray radiation required for a CT scan is much more than for a single x-ray image, but is generally still a relatively low dose. The risk of damage from the radiation dose used in CT scanning is considered to be very low, but it is not entirely harmless. As a rule, the higher the radiation dose, the higher the risk. The larger the body part scanned, the higher the radiation dose. Repeated CT scans over time result in an overall increase in dose. The younger you are when you have a CT scan, the higher your lifetime risk of developing cancer or leukemia.

Various studies aim to assess the risk of developing cancer or leukemia after a CT scan (see 'Further reading' below). In general, the risk is low. In many situations, the benefits of a CT scan outweigh the risk. However, the same study concludes: ... "Although the clinical benefits should outweigh the low absolute risks, radiation doses from CT scans should be kept as low as possible, and alternative procedures that do not require ionizing radiation, should be considered appropriately. "

Because of the low risk, the Committee on Medical Aspects of Radiation in the Environment (COMARE) has recommended that routine full-body CT scans not be offered as part of “health checks” to patients without symptoms. They also provide various other recommendations for using CT scans (see 'Further Reading' below).

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Further literature and references

  • Committee on Medical Aspects of Radiation in the Environment (COMARE)

  • Pearce MS, Salotti JA, Little MP, et al; Radiation exposure from CT scans in childhood and subsequent risk of leukemia and brain tumors: a retrospective cohort study. Lancet. 2012 Jun 7

  • Hendee WR, O'Connor MK; Radiation Risks in Medical Imaging: Separation of Fact and Imagination. Radiology. 2012 Aug264 (2): 312-21. doi: 10.1148 / radiol.12112678.

  • Meer AB, Basu PA, Baker LC, et al; Ionizing Radiation Exposure and Secondary Cancer Estimation in the Age of High-Speed ​​CT Scanning: Medicare Population Projections. J Am Coll Radiol. 2012 Apr 9 (4): 245-50. Thu: 10.1016 / j.jacr.2011.12.007.

  • Konda SR, Goch AM, Haglin J, et al; Ultralow dose CT (REDUCTION protocol) for assessing limb fractures is just as safe and effective as conventional CT: An assessment of quality results. J Orthopedic trauma. 2018 May 32 (5): 216-222. Doi: 10.1097 / BOT.0000000000001137.

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