If your doctor has recommended a CT scan, you might be feeling a mix of emotions – curiosity, anxiety, and maybe even a little fear.

What is a CT scan? And what can you expect from the procedure? In this comprehensive guide, we will answer all questions that you may have related to CT scans, and explain the process step by step.

The Science Behind CT Scans

To truly understand CT scans, it is helpful to learn about the science that powers this remarkable imaging technology.

1. X-ray Technology: At the core of CT scanning is X-ray technology. X-rays are a form of electromagnetic radiation, similar to visible light but at a much higher energy level. When X-rays pass through the body, different tissues (like bones, organs, and muscles) absorb varying amounts of radiation, creating a shadow on the detector.
2. Cross-Sectional Imaging: CT scans, unlike regular X-rays, create detailed 3D images of the body’s internal structures by taking cross-sectional images from multiple angles. A rotating X-ray source and detector capture a series of images, which are then processed by a computer to generate the 3D-like images.
3. Contrast Agents: In some cases, a contrast agent, usually iodine-based, is administered to enhance the visibility of certain structures or abnormalities. It is particularly useful for highlighting blood vessels and soft tissues that may otherwise be difficult to discern.
4. Radiation Exposure: It is important to note that CT scans do expose patients to ionising radiation. The dose is typically low and considered safe for most individuals, but it is a factor to be considered, especially for frequent or high-dose scans. Your healthcare team will weigh the benefits of the scan against potential risks, ensuring your safety.

Why are CT Scans Used?

CT scans are an essential tool in modern medicine due to their ability to provide detailed, 3D images of the body’s internal structures. They offer several key advantages:

1. Speed and Precision: CT scans are fast and highly precise, making them ideal for emergencies where quick diagnosis and treatment are critical. They can capture images of the body in a matter of seconds, allowing for rapid evaluation.
2. Detailed Visualisation: CT scans can detect and visualise a wide range of conditions, including bone fractures, tumours, bleeding, and other abnormalities. This level of detail is often crucial for accurate diagnosis and treatment planning.
3. Non-Invasive: Unlike invasive procedures that may require surgery, CT scans are non-invasive, meaning they do not require any incisions or the insertion of instruments into the body. This reduces the risk of complications and shortens recovery times.
4. Versatility: CT scans can be used to examine virtually any part of the body, including the head, chest, abdomen, pelvis, and extremities. This versatility makes them a valuable diagnostic tool in many medical specialties, including radiology, oncology, cardiology, and orthopaedics.
5. Monitoring Changes: CT scans can be used to monitor the progression of diseases or the effectiveness of treatment. Physicians can compare images taken at different times to track changes in a patient’s condition.

The CT Scan Procedure – A Step-by-Step Guide

Now that we’ve delved into the science behind CT scans, let’s explore what to expect when we walk into the imaging department for your procedure.

Preparing for the CT Scan

Before your CT scan, you’ll receive specific instructions from your healthcare provider or the imaging centre. These instructions might include:

• Fasting: For some abdominal scans, you may need to fast for a few hours before the procedure.
• Clothing: Wear comfortable, loose-fitting clothing without metal zippers or buttons. In some cases, you’ll be asked to change into a hospital gown.
• Jewellery and Accessories: Remove any jewellery, glasses, and accessories that could interfere with the X-rays.
• Allergies: Inform the staff if you have any allergies, particularly to contrast agents.
• Medications: If you’re taking any medications, discuss them with your healthcare team to ensure there are no contraindications.

The CT Scanner Room

When you arrive for your CT scan, you’ll be led to the scanner room. This room typically contains a large, doughnut-shaped machine, which is the CT scanner. Depending on the type of scan you’re getting, you might need to lie down on an examination table. The technician will position you carefully to ensure the area of interest is in the scanner’s focus.

Contrast Material

If your scan requires a contrast agent, a nurse or technician may insert an intravenous (IV) line into your arm or hand. The contrast material will be administered through this line, and you may experience a warm sensation as it circulates through your body.

The Scan

The CT scan itself is a painless and quick procedure. You will be asked to remain as still as possible during the scan, which can take anywhere from a few seconds to a few minutes, depending on the type of scan and the area being examined. The scanner may produce buzzing or clicking noises, but don’t worry, as this is completely normal. These sounds are generated by the machine’s internal components and do not indicate any issues or problems. The technologist operating the scanner will ensure that you are comfortable and provide earplugs or headphones to help minimise any discomfort caused by the noise.

During the CT Scan

Understanding what happens during a CT scan can help ease any anxiety you may have about the procedure. Here’s a step-by-step overview of what to expect:

1. Check-In: When you arrive at the imaging centre or hospital, you’ll need to check in with the receptionist or nurse. You may be asked to fill out some paperwork and answer questions about your medical history.
2. Changing into a Gown: In some cases, you may be asked to change into a hospital gown to ensure that no clothing interferes with the scan. You’ll also need to remove any metal objects, such as jewellery, eyeglasses, or hairpins.
3. Positioning: Depending on the part of your body that needs to be scanned, you’ll be positioned on the CT scanner table. The technologist will make sure you are in the correct position and may use cushions or restraints to help you stay still during the scan.
4. Contrast Material: If your scan requires contrast material, it will be administered as discussed with your healthcare provider. Contrast material may be given orally, intravenously, or rectally, depending on the type of CT scan being performed.
5. Breathing Instructions: For certain scans, like chest or abdominal scans, you may be given specific breathing instructions. It is essential to follow these instructions to ensure the images are as clear as possible.
6. Scanner Operation: The CT scanner is operated by a radiologic technologist, who will monitor you from an adjacent room. They will communicate with you through an intercom and observe you on a monitor to ensure your comfort and safety.
7. Table Movement: During the scan, the CT table will move slowly through the scanner’s gantry, which houses the X-ray tube and detectors. You may hear clicking or buzzing sounds as the machine operates.
8. Staying Still: It is essential to remain as still as possible during the scan to avoid blurring the images. The technologist will let you know when it’s safe to breathe and when you should hold your breath.
9. Duration: The duration of the CT scan can vary, but most scans are relatively quick, typically taking just a few minutes. More complex or detailed scans may take a bit longer.
10. Post-Scan Observation: After the scan is complete, you may be asked to wait for a short period while the technologist reviews the images to ensure they are of high quality. If further images are needed, they will be obtained at this time.

After the CT Scan

Once the CT scan is complete, you’ll be able to return to your normal activities. If you received contrast material, you may be asked to drink extra fluids to help your body eliminate it. The technologist or healthcare provider will provide specific instructions. In some people, the contrast material can lead to allergic reactions such as hives, difficulty breathing, or swelling. If you experience any of these, seek medical attention immediately. Severe reactions are rare but not impossible.

The images obtained during the CT scan will be analysed by a radiologist, who will provide a report to your referring physician. Your doctor will discuss the results with you during a follow-up appointment. In most cases, you can resume your regular activities immediately after the CT scan. There are usually no restrictions on eating, drinking, or taking medications post-scan.

CT scans involve a small amount of radiation, which is carefully controlled to minimise risks. The radiation exposure from a single CT scan is generally considered safe. However, it is essential to inform your healthcare provider about any recent CT scans or other radiology procedures to avoid unnecessary radiation exposure.

Potential Risks and Considerations

While CT scans are generally safe and widely used, it is essential to be aware of the potential risks and considerations associated with the procedure.

Sources:

• https://www.mayoclinic.org/tests-procedures/ct-scan/about/
• https://my.clevelandclinic.org/health/diagnostics/4808-ct-computed-tomography-scan
• https://www.healthline.com/health/ct-scan
• https://www.nhsinform.scot/tests-and-treatments/scans-and-x-rays/ct-scan
• https://www.cancer.gov/about-cancer/diagnosis-staging/ct-scans-fact-sheet