CT Scan (Computed Tomography ) - What is it, Types, Procedure & Result

Have you seen doctors advise their patients to undergo a CT scan when they want to investigate and diagnose a problem thoroughly? Standard X-rays and ultrasounds fall short of providing the detailed images required to diagnose certain conditions. Traditional X-rays are excellent for visualising bones in cases of fractures but lack the depth needed for soft tissues and organs. Likewise, ultrasounds are effective for some applications but are limited in clarity and depth. This need for a precise imaging method led to the invention of a Computed Tomography (CT) or CAT scan, popularly known as a CT scan. 

The CT scan revolutionised the medical industry. Sir Godfrey Hounsfield, a British engineer, and Allan Cormack, a South African physicist developed it in the early 1970s.

In this blog, we will learn more about CT scans and CT scans vs. MRIs and delve deeper into what a CT scan is, its benefits, procedures, and associated risks.

What is a CT Scan?

A CT scan provides a comprehensive view of bones, blood vessels, and soft tissues. It combines X-rays with computer technology and offers detailed cross-sectional images of the body, unlike regular X-rays that provide a flat image. This advanced imaging technology provides a reliable and accurate diagnosis, making it an invaluable tool in modern medicine. It helps doctors see inside the patient’s body with greater clarity and detail, which further helps in diagnosing various health issues. 

Common Medical Conditions Diagnosed with CT Scans

A CT scan can help detect several medical conditions; here is a list of the most common ones:

1. Neurological Conditions: CT scans can also detect conditions affecting the brain. It identifies issues such as brain haemorrhage, strokes, and tumours. It can also assess the severity of neurological conditions or head injuries in an accident.

2. Cancers and Tumours: A tomography scan can help identify the size, shape, and location of tumours and monitor the effectiveness of cancer treatments. It can detect liver, lung, brain, and pancreatic cancers.

3. Injuries: In the event of an accident or trauma, a CT scan can diagnose internal injuries like fractures, bleeding or organ damage. They are helpful, especially for assessing complex bone fractures or spinal or head injuries.

4. Infections: CT scans can identify infections in the human body, such as abscesses in organs like the liver or lungs, and infections in the bones, like osteomyelitis.

5. Lung Conditions: CT scans are also helpful in detecting lung diseases, such as tuberculosis, pneumonia, and blood clots in the lungs, known as pulmonary embolisms. They also monitor chronic lung conditions like chronic obstructive pulmonary disease and screen for lung cancer.

6. Cardiovascular Conditions: A CT scan helps diagnose heart diseases or conditions, such as aneurysms, blood clots, and coronary artery disease. It can also detect blockages, evaluate the aorta, or detect other abnormalities in the blood vessels.

7. Musculoskeletal Disorders: A computed tomography scan can detect problems in the muscles and soft tissues. It also diagnoses diseases and conditions affecting bones and joints, such as bone tumours, arthritis, and complex fractures.

8. Stomach/Abdominal Issues: A stomach CT scan identifies issues in the intestines, pancreas, and other abdominal organs. It is effective in detecting causes of urinary tract bleeding. It can also diagnose abdominal problems like kidney stones, appendicitis, and liver diseases. 

CT Scan vs. MRI and Other Imaging Techniques 

Here’s the comparison between CT scans and other types of imaging techniques in India:

How Does a CT Scan Work?

Here’s a step-by-step explanation of a CT scan procedure:

CT Scan Preparation 

A CT scan is performed by a radiographer, who is a specialist in interpreting medical images and reviewing the scans. Before starting with a body scan, the radiographer may ask the patient to change into a hospital gown and remove any metal object, like jewellery, that could interfere with the imaging. They might use a contrast dye to highlight specific body areas in a few cases. Depending on the target area, the dye may be injected, swallowed, or administered rectally.

Positioning for the Scan

The patient must take the correct position before starting the computed tomography scan. He will be asked to lie on a motorised table that slides into the circular opening of the CT scan machine. The patient must remain still during the scan to ensure clear images for an accurate diagnosis.

X-ray Emission

The CT scanner has an X-ray tube that rotates around the patient’s body. As it spins, it emits a series of narrow beams of X-rays from different angles. 

Image Capture

X-ray detectors opposite the X-ray tube capture the X-rays that pass through the patient’s body. Each rotation produces numerous cross-sectional images, or slices, of the area being examined for diagnosis.

Image Processing

After the patient’s scan, a powerful computer processes these X-ray beams and converts them into detailed, cross-sectional images of the body. These slices are then stacked together to form a three-dimensional image, providing a comprehensive view of the patient’s body’s internal structure.

Review and Analysis of the Images

Finally, the radiologist reviews and analyses the scans for abnormalities like tumours, fractures, infections, or other medical conditions. After the review, they share a detailed report with the patient’s referring doctor. 

Types of CT Scans

Let’s understand the different types of CT scans:

Contrast vs. Non-contrast CT Scans

Contrast and non-contrast CT scans both have their advantages and specific applications: 

The use and choice between the two depends on the specific medical condition and the patient’s overall health. 

Specialised CT scans: PET-CT Scan for Cancer

It is an advanced imaging technique that combines positron emission tomography (PET) and computed tomography (CT) to provide detailed information about the body’s anatomy and metabolic activities.  It is often used to diagnose and manage cancer. 

PET-CT scans for cancer help detect cancer at an early age by identifying areas of increased metabolic activity. They determine the extent of the cancer and help to plan an appropriate treatment accordingly. PET-CT scans also help track cancer treatment efficacy by comparing visuals over time and identifying cancer recurrence earlier than other methods. PET-CT scans can detect different types of cancer in the body, such as lung, head, neck, breast, thyroid, melanoma, and lymphoma.

A PET-CT scan can also check for:

• Heart attack
• Coronary artery diseases
• Heart problems
• Brain disorders
• Brain tumours
• Epilepsy
• Dementia
• Alzheimer’s disease

Why Do You Need a CT Scan?

A computed tomography scan can image nearly every part of the body. Here are the different body parts that can be scanned by a CT scan, along with common medical conditions and the purpose of the scan:

CT Scan for Chest 

It is helpful in evaluating chronic lung conditions like COPD and identifies lung infections such as pneumonia and tuberculosis. The CT Scan done for chest also detects lung cancer and tumours.It is also used to assess the  pulmonary embolism (blood clots in the lungs) and  examining the heart and major blood vessels for cardiovascular diseases.

CT Scan for the Brain and Head

It is performed for evaluating brain functioning and diagnosing strokes. The CT Scan also detects the brain tumours and any kind of bleeding or swelling in brain, which could lead to further head injuries. 

CT Scan for the Spine

It is always recommended by the doctors if you are planning for spinal surgery. It is performed to diagnose spinal injuries and detect any specific spinal injury, tumours or herniated discs. To avoid any further possibility of degenerative diseases like spinal stenosis. 

CT Scan for the Stomach, Abdomen, and Pelvis

It is suggested by the doctors for diagnosing appendicitis and evaluating the pancreatic conditions. It detects the liver diseases, tumours, kidney stones, and ovarian or uterine conditions in women. It also checks the bowel obstructions caused by inflammation.  

CT Scan for Bones and Joints

It aids in diagnosing osteomyelitis (bone infection) and dentifying fractures and bone injuries. It also detects the bone tumours, cysts and post-surgical complications, which could lead to severe joint problems like arthritis. 

CT Scan for the Neck

It checks the vascular problems in neck arteries and thyroid conditions. Also helps in  assessing neck masses,tumours, and lymph nodes for injections or cancer. 

CT Scan for Heart and Blood vessels

If you are planning for cardiovascular surgeries, it is necessary to evaluate the coronary artery disease through CT Scan for heart and blood vessels. It also detects aneurysms to assess blood vessel blockages or malformations.  

CT Scan for Arms and Legs (extremities)

It is beneficial to diagnose tumours or infections in extreme cases like fractures, bone injuries, and vascular conditions in limbs. It is also effective in detecting soft tissue injuries like muscle tears. 

How to Prepare for a CT Scan?

To yield accurate results and make the scanning process smooth, here’s a quick guide on how to prepare for a body scan:

• Proper Clothing: Wear comfortable, loose clothing. Leave all accessories at home before the CT Scan. 
• Allergy: If you have any allergic reaction to any contrast media, you should inform the person performing the CT Scan. 
• Be Punctual: Arrive early at the diagnostic centre and follow the instructions given by the practitioner.
• Medication: Always inform about the medical conditions or reactions priorly. You can continue with prescribed drugs unless advised otherwise.

What Should I Expect During the CT Scan Procedure?

CT Scans are usually performed on an outpatient basis. The procedure might depend on the medical condition and the doctor's recommendation. Here’s what you can expect during a CT scan procedure:

• You might be asked to change into the patient gown. All your piercings and jewellery will be removed so that they do not interfere with the CT Scan. 
• If your scan is performed with contrast, an IV line will be started in the hand or arm for injection of the contrast media. In the case of oral contrast, you will be given a liquid contrast preparation to swallow.
• You will be asked to lie down on a scan table that slides into a large, circular opening of the scanning machine.
• The practitioner performing the scan would be in another room. But would be in constant contact with you through speakers and a call button. 
• As the scanner starts to rotate, the X-rays pass through the body with a clicking sound from the CT Scan machine. Keep still and hold your breath as directed.
• When the procedure is complete, you will be removed from the scanner. Drink plenty of water to get rid of the contrast agent.
• While the CT procedure itself causes no pain, but if you experience any discomfort, you should inform the doctor. 

What are the Side Effects of a CT Scan? 

CT scans are non-invasive and safe, but there are certain risks and side effects to be aware of:

• Contrast Dye Reaction: In some rare cases, the contrast dye used in the CT Scan might cause some allergic reactions like mild itching and anaphylaxis. Patients may experience a warm sensation when contrasts spread through the body.
• Radiation exposure: The ionising radiation might increase the cancer risk. This risk is higher in pregnant women and children. 
• Discomfort: A type of metallic taste is common with IV contrast agents. There is also a possibility of nausea after receiving a contrast agent. Physical discomfort can also be felt due to mobility issues.

How Do You Minimise CT Scan Risks?

Minimise the risks and side effects of the CT scan of the CT scan by following these steps:

• Inform the doctor about allergies and past medical conditions.
• Stay hydrated before and after body scans.
• Follow the pre-scan and post-scan instructions properly. 

Medical Conditions to Consider Before a CT Scan

Before undergoing a CT scan, it’s highly recommended that you consider the following medical conditions:

• Chronic or acute kidney problems
• Pregnancy
• Allergies, especially to contrast material
• Thyroid disorders
• Heart conditions
• Asthma
• Diabetes, particularly if taking metformin
• Dehydration

Inform your healthcare provider about these conditions, as this will help plan the scan safely and effectively.

Wrapping Up!

A CT scan is the most common test for diagnosing underlying medical conditions. It is a vital tool for modern medicine that provides detailed, high-resolution imaging that surpasses regular X-rays. It is versatile and accurately diagnoses most conditions, from tumours to cancers. For any treatment diagnosis, a body scan is essential; if you have health insurance coverage, your expenses can be mitigated. 

 >> Also Read: Migraine Headaches - Causes, Symptoms, and Treatments

Disclaimer: The above information is for reference purposes only. Kindly consult your general physician for verified medical advice. The health insurance benefits are subject to policy terms and conditions. Refer to your policy documents for more information.