Computed tomography or CT scan: how does it work? (2023)

A computed tomography (CT) scan, or computed axial tomography (CAT), combines data from multiple X-rays to create a detailed picture of structures within the body.

CT scans produce two-dimensional images of a "slice" or section of the body, but the data can also be usedbuildThree-dimensional images. A CT scan can be compared to looking at a slice of bread in a whole loaf.

CT scans are used in hospitals around the world.

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A CT scanner sends a series of narrow beams through the human body as it moves through an arc.

This differs from an X-ray machine, which emits only one beam. Computed tomography produces a final image that is more detailed than an X-ray.

The CT scanner's X-ray detector can detect hundreds of different density levels. He can see tissue inside a solid organ.

This data is transmitted to a computer, which creates a 3D cross-sectional image of the body part and displays it on the screen.

Sometimes a contrast agent is used because it can help show certain structures more clearly.

For example, if a 3D abdominal scan is required, the patient may need to have a barium meal. Barium appears white on the scan as it travels through the digestive system.

When below body images are required, e.g. B. the rectum, the patient may be given a barium enema. If blood vessel imaging is the goal, a contrast medium is injected into the veins.

The accuracy and speed of CT scans can be improved using spiral CT, a relatively new technology. The beam spirals as it scans, capturing continuous data with no gaps between images.

CT is a useful tool to aid diagnosis in medicine, but it is a source of ionizing radiation and can potentially cause harm.Krebs.

National Cancer Instituteto advisePatients discuss the risks and benefits of CT scans with their doctors.

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It is useful to get images from:

  • soft fabrics
  • to kiss
  • blood vessels
  • Thrust
  • Brain
  • Abdomen
  • Osso

CT is often the preferred method for diagnosing many types of cancer, such as liver, lung andpancreas cancer.

Imaging allows a clinician to confirm the presence and location of aTumor, its size and how much it affected adjacent tissues.

A head scan can provide important information about the brain, such as whether there is bleeding, swollen arteries, or a tumor.

A CT scan can reveal a tumor in the abdomen and any swelling or swellinginflammationin nearby internal organs. May show spleen, kidney or liver damage.

Because CT scan detects abnormal tissue, it is useful for planning areasradiotherapyand biopsies, and can provide valuable data on blood flow and other vascular disorders.

It can help the doctor to assess the patient's bone disease, bone density and spinal condition.

It can also provide important data about injuries to a patient's hands, feet, and other skeletal structures. Even small bones are clearly visible, as are the surrounding tissues.

CT versus MRT

The main differences between CT andMRTit is:

  • A CT scan uses X-rays, but an MRI uses magnets and radio waves.
  • Unlike an MRI, a CT scan does not show tendons and ligaments.
  • MRI is best suited for examining the spinal cord.
  • A CT scan is best suited for cancer,pulmonary infection, abnormal chest x-rays, bleeding in the brain, especially after an injury.
  • A brain tumor is more clearly visible on MRI.
  • A CT scan will show organ tears and organ damage more quickly, so it may be better suited for trauma cases.
  • Broken bones and vertebrae are more visible on a CT scan.
  • A CT scan provides a better picture of the lungs and the organs in the chest cavity between the lungs.

The patient may need to abstain from food and possibly alcohol for a period of time before the test.

In day

In most places, the patient is obliged to undress, usually down to his underpants, and put on an apron provided by the health centre. Avoid wearing jewelry.

If the hospital does not provide an apron, the patient should wear loose clothing without metal buttons and zippers.

Some patients may need to drink a contrast medium, or the contrast medium may be given as an enema or injected. This improves the image of some blood vessels or tissues.

Any patient who has an allergy to the contrast medium should inform the doctor in advance. Some medications can reduce allergic reactions to contrast media.

As metal interferes with the operation of the scanner, the patient must remove all metal jewelry and accessories.

during scanning

The patient has to lie down on a motorized examination table that slides into a ring-shaped CT scanner.

In most cases, the patient lies on his back. But sometimes they may need to lie on their stomach or side.

After an X-ray, the sofa moves slightly, and then the machine takes another picture, and so on. For best results, the patient must be very still.

During the exam, everyone except the patient leaves the room. An intercom system allows two-way communication between the X-ray technician and the patient.

If the patient is a child, a parent or adult can stand or sit nearby, but must wear a lead apron to avoid radiation exposure.

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A CT scan involves a small targeted dose of radiation.

Such radiation exposure has not been shown to be harmful, even in people who have had multiple scans.

The chance of developing cancer as a result of a CT scan is thought to be lowless than 1 in 2000.

The amount of radiation involved is estimated to be approximately the same as what a person would be exposed to during a period of several months to several years of natural exposure to the environment.

A scan is only performed if there is a clear medical reason for doing so. The results could lead to the treatment of conditions that could otherwise be serious. When the decision is made to perform a test, doctors ensure that the benefit outweighs any risk.

Problems that can arise from radiation exposure include cancer and thyroid problems.

This is extremely unlikely in adults as well as children. However, they are more susceptible to the effects of radiation. This does not mean that it will lead to health problems, but all CT scans should be noted in the child's medical record.

In some cases, only a CT scanyou can showthe required results. For some conditions, aultrasonicor MRI may be possible.

Can I have a CT scan if I am pregnant?

Any woman who suspects that she is pregnant should inform her doctor in advance, as there is a risk that the X-rays could harm the fetus.

Quoting the American College of Radiography, the American Pregnancy Association (APA) advises that "no single diagnostic radiograph has a radiation dose significant enough to cause adverse effects in a developing embryo or fetus."

However, the APA notes that CT scans are not recommended for pregnant women "unless the benefit clearly outweighs the risk."

tomography and breastfeeding

If a nursing mother needs an intravenous iodinated dye as a contrast agent, she should avoid breastfeedingabout 24 hourshow can it pass into breast milk.

I have claustrophobia: can I have a CT scan?

A patient who hasclaustrophobia Should sayyour doctor or radiologist in advance. The patient may be given an injection or pill before the exam to calm him down.

Your doctor can usually recommend a suitable facility for a scan. You can verify if a radiologist is accredited by searching the websitewebsiteof the American College of Radiology.

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