CT Scan: Purpose, Procedure, Side-Effects and Risks


A CT scan, or Computerized Tomography, comprises a sequence of X-ray imaging taken from various angles and uses a computer system to produce cross-sectional slices (images) of the soft tissues, blood vessels and bones inside your body. Since it provides more accurate and detailed imaging results than X-rays, it is recommended to examine patients who may have succumbed to internal injuries from an injury or other health condition.

It is also known as Computed Axial Tomography (CAT) scan and can be used to examine almost all body parts, including internal organs, tissues and blood vessels. Your doctor may prescribe the procedure to diagnose an internal injury or an underlying disease as well as to recommend surgical or medical treatment. The tomography scan is also used before starting radiation treatment.


A CT examination has several uses; however, it is primarily used to examine the impact of injuries or to diagnose diseases. It can be used for a wide range of purposes such as to:

  • Identify disorders of the bone or muscles, including fractures or bone tumours
  • Diagnose and monitor various health conditions and diseases like cancer, liver masses, lung nodules or heart disease
  • Detect the precise location of a blood clot, infection, excess fluid or tumour
  • Identify and evaluate bleeding or internal injuries that may be caused by an accident or fall
  • Suggest treatment procedures and plans like radiation therapy, biopsy or surgery
  • Identify if a treatment plan is working and what the results are. For instance, scanning a tumour will help understand how it is responding to radiation or chemotherapy

 How is a CT Scan Performed?

Preparing for the Scan

A CT scan does not require much preparation as it is a non-invasive procedure used to thoroughly examine different parts of the body. Your doctor might suggest you not to eat or drink anything for a few hours prior to the procedure. You are also required to change into a hospital gown and remove all metal objects like jewellery, eyeglasses, belt, dentures, etc.

If you have metal inside your body such as a pacemaker, notify the same to the technician who will perform the scan. Metal can interfere with the accuracy and quality of image results.

During the Procedure

A CT scanner is shaped like a doughnut with an opening that leads to a tunnel. The patient is glidedin through this tunnel on a motorised table and pillows and straps are used to ensure you stay in position. If your head is being scanned, the table may have a special mechanism that allows holding your head still in position.

Depending on the part of the body being scanned and the level of imaging accuracy desired, a special dye or contrast material may be administered. The dye inhibits the X-rays and gives the impression of being white on images. This helps emphasise the internal organs, blood vessels, intestines and soft tissues better. The contrast material may be administered to you via injection, orally or inserted in the rectum.

After administering the dye, you will be laid down on the table and moved into the scanner. During this time, the X-ray tube and detectors inside the CT scanner will rotate at various angles and capture numerous images in thin slices of the body part. The process may cause whirring and buzzing noises and you should not feel nervous. The technician will be in another room, communicating with you through the intercom. 

At certain points during the procedure, you may be asked to hold your breath to avoid the images from betting blurred. Depending on the body part being scanned and its complexity, a CT scan may take anywhere from a few minutes to half an hour to complete. It is important to lie still when the images are being taken or otherwise, it can blur the pictures.

 After the Procedure

After the scan, you may return to your daily routine almost immediately. If you were administered contrast material, you may be required to wait for sometime to ensure you feel better after the scan. Your doctor may recommend you drink plenty of fluids to allow the kidneys to remove the dye from your body.

 What are the Risks of CT Scans?

During a CT examination, X-rays are used which can expose your body to a certain level of ionising radiation. Since the procedure gathers more accurate and detailed imaging results, the radiation exposure is relatively higher than a normal X-ray. However, only low doses of radiation are used in the process and have not been identified to cause any long-term harm.

But at higher doses, the ionising radiation may increase your risks of developing cancer at a later stage. This is especially true for patients who are required to undergo a scan frequently. The radiation from the scan is also potentially harmful to unborn babies and children. So, notify the doctor if you are pregnant.

Although rare, the special dye given to you during the CT scan may cause allergic reactions or medical reactions. Consult the doctor immediately in such cases.

 Cost of CT Scan

Depending on the part of the body being scanned, the CT scan price in India may range between INR 1,500 and INR 4,000 per study.

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