CT scans (computed tomography)

A CT scan is a powerful diagnostic test that shows bones, organs, blood vessels and soft tissues in fine detail. It is commonly used to:

• Detect or stage cancers and monitor response to treatment
• Investigate unexplained symptoms such as pain, breathlessness, neurological changes or weight loss
• Assess injuries following trauma, including fractures and internal bleeding
• Examine blood vessels (CT angiography) for problems such as aneurysms or narrowing
• Plan and guide treatments such as surgery, radiotherapy or interventional radiology procedures

Your consultant will request the most appropriate CT scan for your needs, which may involve a contrast injection to highlight blood vessels and organs more clearly.

You may be referred for a CT scan at The London Clinic if you:

• Have symptoms that need detailed imaging to identify the cause
• Have a known condition, such as cancer, and your team needs to track how it is responding to treatment
• Have had an accident or injury and your doctors need to check for internal damage
• Are being assessed before surgery or other major treatments and your surgeon needs precise anatomical information

CT scans are suitable for most adults. They are generally not recommended during pregnancy unless there is an urgent clinical need, due to the use of X‑rays. If you are pregnant, might be pregnant, or have kidney problems, diabetes, severe allergies or asthma, it is important to let the team know in advance, especially if contrast dye may be used.

CT imaging offers several advantages compared with standard X‑rays and some other tests:

• Highly detailed images – CT provides clear cross‑sectional and 3D views of internal structures, helping specialists detect abnormalities that may not be visible on plain X‑rays.
• Fast and efficient – scans usually take only a few minutes, which is particularly valuable in emergencies or when decisions need to be made quickly.​
• Versatile – CT can be used to image almost any part of the body, from head and chest to abdomen, pelvis, spine and limbs.​
• Guides treatment planning – precise images help your team choose the most appropriate surgery, radiotherapy field or interventional procedure, and monitor how well treatments are working over time.

For most patients, the diagnostic benefits of a CT scan greatly outweigh the risks. However, it is important to be aware of:

• Radiation exposure – CT uses a small dose of ionising radiation. At The London Clinic, the dose is carefully controlled and kept as low as reasonably possible while still producing high‑quality images.
• Contrast reactions – some scans use an iodine‑based contrast dye injected into a vein. This can occasionally cause a warm feeling, metallic taste, mild flushing or nausea, which usually pass quickly. Rarely, more serious allergic reactions can occur; our staff are fully trained and equipped to manage these.
• Kidney effects – in a small number of people with existing kidney problems, contrast dye can temporarily affect kidney function. This is why we sometimes check blood tests beforehand and encourage good hydration afterwards.
• Contrast extravasation – if contrast leaks from the vein into the surrounding tissue, you may experience stinging, pain and swelling at the injection site; this is usually minor and settles with elevation and cold compresses over a few days.​

Your radiographer and radiologist will review your medical history, allergies and recent blood tests to assess your individual risk and take steps to keep you safe.