What Is A CT Scan?

A CT scan is a radiological examination that uses X-ray. The examination is performed in a CT examination room with the patient placed and positioned on the examination couch in order to acquire images of the area under examination. Contrast media will be used in most CT examinations to visualise the structures better [1].

How Can I Get This Examination Done And Where?

  • The doctor you are seeing will decide if you need the examination.
  • If necessary, the doctor will make a request for examination using Request Form For Radiological Examination.
  • This examination is available in selected Ministry of Health hospitals.

CT Scanner

  • A CT Scanner produces cross-sectional images.
  • Using advanced computer technology, images taken can be processed to visualise the organs, tissue or bone clearly.
  • The word ‘computerised’ is used because the process of image acquisition is performed by using advanced computer technology, while the word tomography refers to cross-sectional images acquired during the scan. [1]

How Does A CT Scanner Look Like?

Main Components of the scanner are:

Examination room

  • Gantry (Picture 1)

– Contains the X-ray tube.

– Contains a detector.

  • Examination couch (Picture 1)

– A place to position the patient for the examination.

– Will be moved in and out by the radiographer.

  • Accessories

– injector (for injection of contrast medium).

– monitor (acquired images can be viewed from inside of the examination room).

Control room (Picture 2)

  • Used by the radiographer during the examination.
  • Where images are processed.
  • Where images are displayed.
ct_scan_1 ct_scan_2
Picture 1: CT scanner Picture 2: CT control room


Types Of CT Examinations

  • Some of the examinations that can be performed are:
  • Skull and brain.
  • Thorax (chest area).
  • Abdomen and pelvis.
  • Spines (Vertebral column).
  • Upper and lower extremities.

What Is The Preparation For A CT Examination?

  • At the time of making an appointment you will be given a preparation slip and an explanation on how to prepare for the examination. These include:
  • Nil by mouth for 4 – 6 hours prior to the examination.
  • Only plain water is allowed.
  • Taking steroid medication (if given).
  • Inform the doctor or radiographer if you have previous history of:

– Asthma;

– allergy to certain food or medication (itchiness, rashes and swelling).

  • please consult your doctor if you are on any medication.
  • Inform the doctor and/ or radiographer if you are or may be pregnant.

On the day

  • Present yourself at the registration counter.
  • Before the examination
  • You will need to change into a hospital gown which will be provided.
  • Valuables and personal items are your own responsibility. (You are advised not to bring any valuables with you on the examination day).
  • Inform the doctor and/ or radiographer if you are pregnant or may be pregnant.
  • Referring to the preparation slip given to you when making the appointment, you will be asked if you are prepared for the examination.

What are the reasons that might cause your CT examination be postponed?

  • Not fasting.
  • Not taking the steroid as required.
  • You are pregnant or may be pregnant.

During the examination

  • You will be asked to lie down on the examination couch.
  • The radiographer will position you according to the area to be examined.
  • Please cooperate by following the instructions given by the radiographer.
  • The examination couch will move and it will be slight noisy during the scan. Do not worry and do not move.
  • You will be alone in the examination room during scanning.
  • You can talk to the radiographer through the intercom.
  • The scanning process will take between 30 – 60 minutes depending on the part to be scanned.

After the examination

  • You will be taken out of the examination room.
  • You will be asked to change back into your clothing.
  • Injection needle will be taken out (if any).
  • Make sure you are well before leaving the department.
  • If you are have any problem, please inform the doctor or radiographer on duty.
  • You may have your normal food after the examination.

Use Of Contrast Media

For certain examinations a contrast media will be introduced into your body through:

  • Injection.
  • Ingestion (oral).
  • Rectal (through the anus).

Contrast media is used to visualise the organs better and may cause you to feel:

  • Warm.
  • Nausea.
  • Dizzy.

– However, this is usually temporary. If it persists please inform the radiographer on duty.

– You need not worry because our doctor is present throughout the examination.


Images acquired during the examination will be viewed by the radiologist who will then report the examination.


  1. Computed Tomography (CT) Scans and Cancer, 2013, National Cancer Institute, US, http://www.cancer.gov/cancertopics/factsheet/detection/CT



Last Reviewed : 2 June 2016
Translator : Daud bin Ismail
Accreditor : Jasintha S. Sangarapillai