How does a CT scan actually work?

How does a CT scan actually work?
The human body is a structure comprising of numerous muscles, tissues, organs and blood vessels, all working together. Just one malfunctioning organ can have massive consequences on the body.
With the advancement of medical technology, CT scans are able to provide detailed images of various organs, providing doctors with an invaluable diagnosis tool to help identify and manage any problem areas.

CT Scans aid the creation of a treatment plan

CT (Computed Tomography) Scan: A Computed Tomography Scan allows an all-inclusive image relevant for clear and comprehensive diagnoses. A CT Scanner assists to detect a variety of diseases with accuracy. It is fast, non-invasive and painless. It can expose internal injuries, breaks and bleed quickly to help manage a wide range of medical conditions.

Using similar principles to X-rays, a CT scan passes X-rays through the body, which are then either absorbed or depleted at distinct levels generating a matrix of different strength, resulting in a more dynamic X-ray. It captures images of the organs at 360 degrees.. In other words, it is a three-dimensional computer model of the body.

What does the machine like?

A CT scanner looks like a big, square, doughnut it is often referred to as a polo mint. The CT scanner has 3 primary systems, each of which is composed of various sub-components.

1) Gantry

The Gantry is the largest of all three systems and consists of equipment related to a patient’s support such as:

  • Positioning couch
  • Mechanical support
  • Scanner house
  • Heart of the scanner- Xray tube.

2) Control console/computer

This is the computer specially designed to manipulate the data of X-rays received from the gantry.

3) Operating console

This is the master control centre of the CT scanner. The operating console is used to input all the factors related to take a scan and consists of multiple monitors. This is where the radiographers set the protocols for the scanning sequence these protocols dictate to the scanner which areas of the body to focus the attention on.

How does a CT scan actually work?

Imagine a CT scanner to be like a large box within a tunnel.

The patient needs to lie on a table that slides in and out of the tunnel.

At the same time, the scanner (X-ray tube) rotates around the patient.

The scanner shoots narrow beams of x-rays through the body.

Cross-sectional images of the body organs are produced.

These images are displayed on computers in a separate room operated by the Radiographer.

The Radiographer in the room can speak with the patient through speakers and microphones.

The digital x-ray detectors are used the opposite to the X-ray source.

As the x-rays pass through the patient’s body and leave the body, the detectors pick them.

The detectors transmit them to the computer, to produce a 2D image “slice”.

A 2D image slice is constructed as the x-ray source completes one rotation.

The image is stored and the bed is then again moved forward slightly into the gantry.

This process is repeated until the desired number of slices are collected.

These images can be displayed individually or can be stacked together by the computer to generate a 3- D image view of the patient. Tissues, bones and organs are clearly visible and abnormalities can be identified by the Radiologist.

To locate the exact position of the abnormality the slices can be viewed in succession to make it easier.

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For more information on CT scans at Pall Mall Medical,

Please contact our Imaging Department on 0330 058 44 55, or email

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