Radiological tests

People who are seriously ill and admitted into the intensive care unit (ICU) will have a wide variety of radiological tests done. These tests help to diagnose medical problems or to see how well their treatment is working.

Some of the common radiological tests that may be done while a person is in the ICU may include:

Chest x-ray

A chest x-ray takes a picture of your chest cavity by using a small burst of radiation that passes through your body. The picture is recorded on film or a digital recording device.

Why is it done?

A chest x-ray is a very useful tool for picking up possible problems, and is used as a way to check the progress of a patient. It is common for a person in ICU to have frequent chest x-rays. A chest x-ray will also be done to check that lines, tubes and catheters inserted are in the right place.

What can a chest x-ray find?

A chest x-ray can pick up:

  • changes in the size and shape of the heart
  • problems in the major blood vessels of the body
  • fluid build up in the air sacs of the lungs
  • lung problems, including collapse of the lung, pneumonia, tumours and air build up around the lungs (pneumothorax)
  • the position of the lines and tubes used in the ICU.

How is a chest x-ray done?

A person in the ICU will usually have their chest x-ray taken in their bed. The x-ray technician uses a portable machine and takes the x-ray with the ICU nurse supervising. The person is sat as upright as possible, and the x-ray plate is placed behind them. Those who are conscious (not sedated or in a coma) will be asked to hold their breath. When taking a chest x-ray for a person who is ventilated (has assisted breathing), the technician will take the x-ray in time with the ventilator.

What are the risks of a chest x-ray?

There are very low risks of having a chest x-ray, because only a small amount of radiation is used. During the x-ray, the person may be uncomfortable for a few minutes. You may hear the x-ray technician say “x-ray” while doing the procedure. This is to alert the staff in the ICU that an x-ray is being taken.

How long before the x-ray results are back?

The intensive care doctors are able to view the chest x-ray within minutes of it being taken, and will be able to pick up most problems. Most ICUs have a special viewing room, where all x-rays are kept or a digital image can be seen. A radiologist, a specialist in reading x-rays, will examine the image and give a proper report. If there are any serious problems, the results will be discussed with you.

Computed tomography (CT)

CT scans are a special kind of x-ray that are able to show more detail than regular x-ray. Common areas that CT scans are helpful for include the brain, chest and abdomen. A contrast dye may be used used.

The intensive care patient will be taken to the x-ray department for the scan accompanied by an ICU doctor and nurse. The CT scanner looks like a large square donut with a narrow table in the middle.

Magnetic resonance imaging (MRI)

MRI, or magnetic resonance imaging, uses a powerful, constant magnetic field to create very clear pictures of internal body structures. MRI is a very safe test. However, because magnetic fields are used, it is important that you let the ICU doctors and nurses know about any metallic objects that may be inside the ICU patient’s body. You will be asked to help staff to complete a comprehensive checklist to identify these objects.

Positron emission topography (PET) scans

The PET scan detects which areas in the body have cells that are highly active. The doctor uses this information to help diagnose and manage the medical condition of a person admitted to the ICU. The scan can give more information after the person has had x-rays, a CT scan, MRI, nuclear medicine or laboratory procedures. With PET scans, the person is exposed to a small amount of radiation, though this level is not a threat to health.

To have the test, the person will be taken to the x-ray department, and will be accompanied by an ICU nurse and doctor.


Ultrasound scanning, also called sonography, uses sound waves to produce images of structures inside the body. There are no known risks for sonography and the scan can be done safely at the bedside in the ICU.

Any questions?

If you have any questions or concerns, please discuss them with the ICU nurses and doctors.

Publication details

Version 1.1. First published 2015. Next review 2023.


The information on this page is general in nature and cannot reflect individual patient variation. It reflects Australian intensive care practice, which may differ from that in other countries. It is intended as a supplement to the more specific information provided by the doctors and nurses caring for your loved one. ICNSW attests to the accuracy of the information contained here but takes no responsibility for how it may apply to an individual patient. Please refer to the full disclaimer.