Computerized Tomography (CT Scan)

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[lwptoc] What is a CT scan? A computerized tomography (or CT as it’s shortly known) scan is a scanning technique that uses computers and rotatory X-ray machines to create cross-sectional images of the body. Images from CT scans provide more in-depth information than normal X-ray images. They are able to show the soft tissues, the… Read More

Computerized Tomography (CT Scan)


What is a CT scan?

A computerized tomography (or CT as it’s shortly known) scan is a scanning technique that uses computers and rotatory X-ray machines to create cross-sectional images of the body. Images from CT scans provide more in-depth information than normal X-ray images. They are able to show the soft tissues, the blood vessels, and the bones in various parts of the body. 

CT scan can be used to envision the

  • Head,
  • Shoulders,
  • Spine,
  • Heart,
  • Abdomen,
  • Lungs,
  • Soft tissue,
  • Knee, and
  • Chest.

In the course of a CT scan, patients lie in a tunnel-like part of the machine, while the inside rotates and takes series of X-rays from different angles. These pictures sent to a computer, where they are combined together to produce images of slices or cross-sections of the body. They may also be combined to create 3D images of a particular area of the body.

Why is a CT scan carried out?

CT scan may be recommended for several reasons such as to;

  • Detect disorders of the muscles and bones, such as bone tumors and/or fractures.
  • Pin down the exact location of a tumor, an infection or a blood clot.
  • Serve as a guide in procedures, for instance, surgery, biopsy and radiation therapy.
  • Identify and monitor diseases and conditions such as cancer, lung nodules, heart disease, and liver masses.
  • Monitor the efficiency of certain treatments, for instance, cancer treatment.
  • Discover internal injuries and internal bleeding.
  • Obtain important information about the brain. For instance, to check for bleeding, swelling of the arteries, or a tumor.
  • Detect any swelling or inflammation in nearby internal organs. It can also show any lacerations of the spleen, kidneys, or liver.

Preparation for a CT scan. 

Preparation for a CT scan depends on the part of the body to be scanned. However, in general terms, some of the things you may be required to do are

  • Taking off some or all of your clothing to put on a hospital gown.
  • Removal of metal objects, such as a belt, jewelry, and eyeglasses, as they might interfere with image results.
  • Abstain from eating or drinking for a few hours before the scan.

How does a CT scan work? 

CT scan machines are doughnut-shaped or tunnel-like. The first step is proper positioning. A patient lies on the narrow, motorized table, which slides through the opening into the tunnel. Should the need be, straps and pillows may be used to aid positioning. For head scan, the table may be fitted with a special cradle to help hold the head still. 

After the table moves into the scanner and properly positions it, the detectors and the X-ray tube rotate around the patient to generate several images of thin slices of the body. While this rotation is ongoing you may hear buzzing, clicking, and whirring noises that may be uncomfortable. However, it is very important to stay still, as movement may lead to generating blurry pictures. The patient may also be asked to hold breathing, should it be found necessary to. The entire procedure may last between 20 minutes to one hour.

During the scan, only the patient will be in the room. However, an intercom will be provided to enable two-way communication between the patient and the radiographer.

As soon as the CT scan is over, the images generated are sent to a radiologist (a doctor with a specialty in diagnosing and treating conditions using imaging techniques, like CT scan, MRI etc.) for examination. 

How to read a CT scan?

Images generated from a CT scan are stored as electronic data files and are reviewed via a computer screen. A radiologist studies and interprets these images, and sends a report of his findings to the doctor.

If the findings of the radiologist indicate that there was no presence of any abnormalities in the image, such as tumors, blood clots, fractures, or any other abnormalities at all. 

Should there be detection of abnormalities during the CT scan, further tests or treatments, depending on the type of abnormality found, may be recommended.


What happens after a CT scan procedure? 

There shouldn’t be any after-effects from a CT scan. Patients are usually able to go home soon afterward and return to a normal routines, such as eating, drinking, and driving.

In the case whereby a contrast material was given, special instructions will also be given. In some cases, patients may be delayed asked to wait for a short time to ensure there is proper wellness. It is also likely to be asked to drink lots of fluids to help the kidneys remove the contrast material from the body.

CT Scan vs. MRI 

The major differences between a CT scan and an MRI scan are;

  • CT scan uses X-rays, MRI uses magnetic and radio waves.
  • CT scan, unlike an MRI, does not show tendons and ligaments.
  • MRI is better suited for examining the spinal cord.
  • CT scan is more suitable for cancer, pneumonia, abnormal chest x-rays, and bleeding in the brain.
  • A brain tumor is clearer on MRI.
  • A CT scan is more suitable for trauma cases, as it shows organ tears and injury quicker.
  • Broken bones and vertebrae are more discernible on a CT scan.
  • CT scans generate a better quality of images of the lungs and organs in the chest cavity between the lungs.

Does a CT scan pose any risk? 

Exposure to radiation. However, the effective radiation dose for a CT scan procedure varies and has very low chances of complications. In fact, CT scan radiation has not been shown to cause any long term harm 

Harm to unborn babies. If done for a pregnant woman, it may likely cause harm to the baby.

Allergic reaction to contrast material. However, this extremely rare.

What are CT scan side effects?

  • Though on rare occasions, contrast materials can lead to kidney problems. 
  • It can cause itching, rashes, nausea, wheezing and shortness of breath.
  • It can also cause facial swelling that may last up to one hour.

How long does a CT scan take?

Usually, a CT scan procedure lasts between 20 minutes to 1 hour.

Benefits of a CT scan?

  • A CT scan procedure is painless, non-invasive, and accurate.
  • Ability to image bones, soft tissues and blood vessels, all at the same time.
  • CT scan provides very detailed and informative images.
  • Fast and simple.
  • In emergency cases, CT scan reveals internal injuries and bleeding quicker enough, which helps to save lives.
  • Cost-effective.
  • It’s less sensitive to patient movement when compared to MRI.
  • CT scan provides real-time imaging.
  • No radiation leftover in a patient’s body.

Can breastfeeding mothers undergo a CT scan? 

Yes. However, breastfeeding or lactating mothers requires an iodinated intravenous dye for contrast. Therefore, must avoid breastfeeding for about 24-48 hours, as the contrast may pass into the breast milk.