Computed Tomography (CT) and Quantitative CT
What is CT and Quantitative CT?
Computed Tomography (CT) combines X-ray measurements taken from several angles with computer processing to produce detailed cross-sectional images of the body. The images can also be reconstructed in other planes to help clinicians examine anatomy more closely.
CT is useful when rapid, detailed assessment of bones, lungs, internal organs or blood vessels is required. Depending on the clinical question, a CT scan may be performed without contrast or with contrast given by injection or another route.
Quantitative CT uses measurements derived from CT images for particular clinical assessments, such as selected bone-density evaluations. Whether a quantitative study is appropriate depends on the referral and available protocol.
What to expect
- Tell staff if you are pregnant or could be pregnant, and report any previous reaction to CT contrast.
- Mention kidney disease, relevant allergies and medicines that may affect preparation for a contrast-enhanced examination.
- Follow the instructions for your particular CT study; some scans require fasting, drinking contrast or recent kidney-function blood tests.
- Remove metal items from the area being scanned if requested and bring relevant previous imaging information.
- You will lie on a table that moves through the circular opening of the CT scanner.
- The radiographer may ask you to hold your breath briefly or remain still while the images are acquired.
- If intravenous contrast is needed, you may notice a temporary warm sensation or unusual taste; tell staff immediately if you feel unwell.
- The scanning portion is often brief, although preparation and contrast administration may take additional time.
- Most people can resume normal activities after a routine CT examination.
- If contrast was given, follow the team's instructions about fluids and any symptoms to watch for.
- If you received medication or had a more complex procedure, the team may provide additional observation or discharge advice.
- The scan will be reviewed and the findings reported to your referring healthcare professional.
Safety and results
- CT uses ionising radiation. The imaging team selects a protocol intended to answer the clinical question while managing radiation exposure.
- Pregnancy or possible pregnancy must be discussed before the examination so the benefits and alternatives can be considered.
- Iodinated contrast may carry additional risks for some patients, including those with prior contrast reactions or certain kidney conditions.
- Inform staff promptly if you develop itching, breathing difficulty or other unexpected symptoms during or after contrast administration.
Please contact our team if you have questions about your examination or preparation instructions.
A radiologist reviews the CT images and prepares a report for the referring healthcare professional. The report may describe the location, size or appearance of a finding and, when relevant, compare it with previous examinations. Quantitative measurements are interpreted in the context of the requested study. Your referring clinician will discuss the results and any next steps with you.
For questions about your findings or treatment, please speak to your referring healthcare professional.
For questions about your findings or treatment, please speak to your referring healthcare professional.