If your doctor ordered a CT scan, you may wonder why and what the scan does. A CT scan is a non-invasive imaging test that uses many X-ray images taken from different angles to create a detailed picture of the inside of your body. Doctors often use CT scans to find the cause of symptoms such as abdominal pain, chest pain, head injuries or unexplained swelling when other tests don’t give clear answers.
In this guide, you’ll learn more about how a CT scan works and the most common reasons for CTs. Understanding why you need a scan can help you feel more prepared and confident about your care.
Why Do Doctors Order a CT Scan?
Doctors order CT scans when symptoms, injuries, or abnormal test results call for a clearer look inside the body. Common reasons include:
- Suspected fractures
- Tumors
- Blood clots
- Signs of heart disease
- Spinal problems
- Lung disease
A CT scan, short for “computed tomography,” combines X-rays with computer technology to create detailed cross-sectional images of your body from many different angles. A computer then pieces those images together to give your doctor a much more complete picture of your health.
Sometimes your doctor may order a CT scan with contrast dye. Contrast is a special liquid given by mouth or injected into a vein through an IV. The dye highlights certain organs, blood vessels or tissues and makes them show up more clearly on the images.
What Are the Most Common Reasons for an Abdominal CT Scan?
An abdominal CT scan creates detailed images of your stomach area, including organs like the liver, kidneys, intestines, pancreas and major blood vessels. You may need an abdominal CT scan if you have:
- Severe or unexplained abdominal pain
- A mass or lump that you or your doctor can feel in the belly
- Unexplained weight loss
- Internal injuries after trauma
Doctors may order a scan of your abdomen to check for:
- Infections such as appendicitis, which is inflammation of a small pouch connected to the large intestine
- An intestinal obstruction, which means something is blocking the normal flow through your digestive tract
- Inflammatory bowel conditions like Crohn’s disease, which cause ongoing inflammation in the lining of the digestive tract
- Kidney stones, to check their size and location
- Evaluation of known or suspected cancer in the abdominal area
Because so many organs sit close together in the abdomen, your symptoms don’t always point to one clear cause. An abdominal CT can help show which organ the problem is coming from and why.
What Are the Most Common Reasons for a Head or Brain CT?
A head CT creates cross-sectional images of your brain, skull and sinuses. It’s a fast, precise imaging option that can help identify what’s behind persistent or concerning symptoms, so you can get answers without the wait or cost of an emergency room visit.
Your doctor may order a CT scan of your head if you experience any of the following:
- Fainting
- Sudden severe headaches
- Changes in thinking or behavior
- Vision problems
- Muscle weakness
- Trouble swallowing
Doctors use head and brain CTs to evaluate:
- Traumatic injury to the brain, head or face after an accident or fall
- Stroke, which happens when blood flow to a part of the brain is cut off
- Bleeding inside or around the brain
- Brain infections or abscesses, which are pockets of infection
- Brain tumors or growths
- Hydrocephalus, a buildup of fluid inside the skull that can increase pressure on the brain
- Birth defects of the head or brain
Because CT can show bleeding, swelling and structural changes in a single scan, it’s often used to narrow down what’s causing neurological symptoms when both time and clarity matter.
What Are the Most Common Reasons for a Chest CT Scan?
A chest CT scan provides a highly detailed view of your lungs, heart, chest and upper abdomen, making it one of the best tools available for examining soft tissue in the chest.
Your doctor may order a chest CT if you have symptoms such as:
- Chest pain
- Shortness of breath
- A persistent cough
- Fever
- A chest injury from an accident or fall
- A suspected tumor, nodule or abnormal mass spotted on a chest X-ray
- Blood clots in the lungs
- Signs of infection or inflammation, such as pneumonia
- Fluid around the lungs
- Lung scarring or diseases like emphysema, which is a condition where the air sacs in the lungs become damaged and make it hard to breathe
- Enlarged lymph nodes in the chest
A chest CT can help sort out symptoms that often look alike at first. For example, chest pain or shortness of breath could be caused by a blood clot, pneumonia, fluid around the lungs or a lung mass. The scan gives your doctor a closer look at the lungs, pleura and nearby structures so they can better tell these problems apart.
What Is Low‑Dose CT Lung Screening?
Low-dose CT lung screening, also called LDCT, is a specialized CT scan used to look for early signs of lung cancer in people at higher risk. LDCT uses a much smaller amount of radiation than a standard chest CT. The scan creates detailed images of your lungs quickly and painlessly.
Lung cancer often causes no symptoms in its early stages. That’s why screening is so important for people at higher risk. Finding it early, before symptoms appear, can make treatment more effective.
Who Should Get Low-Dose CT Lung Screening?
The U.S. Preventive Services Task Force recommends yearly LDCT screening for adults who meet all three of these criteria:
- Between 50 and 80 years old
- Have a 20 pack-year or more smoking history. A “pack-year” means smoking one pack of cigarettes a day for one year. Smoking one pack a day for 20 years equals 20 pack-years.
- Currently smoke or have quit within the last 15 years
If you think you might qualify, talk to your doctor about whether LDCT screening is right for you. American Health Imaging offers low-dose CT lung screening as part of our commitment to helping patients find answers early.
What Are the Most Common Reasons for a Heart CT Scan?
A heart CT scan creates detailed images of your heart and the blood vessels that supply it. There are two main types of tests:
- Coronary Calcium Scan: Looks for calcium deposits in the arteries that feed the heart. These deposits can be an early sign of heart disease.
- CT Angiography: Looks at the arteries in more detail to check for blockages or narrowing.
Your doctor may order a heart CT scan if you have symptoms such as:
- Chest pain
- Shortness of breath
- Pain that spreads to the jaw, neck or arm
- An abnormal stress test
CT scans of the heart are used to evaluate:
- Plaque buildup in the coronary arteries, which are the blood vessels that bring oxygen to your heart muscle
- Heart disease that was present at birth, also known as “congenital heart disease”
- Problems with the heart valves, which are the flaps that control blood flow between the chambers of the heart
- Blockages or narrowing in the arteries supplying the heart
- Tumors or masses near or on the heart
Some heart CT scans, especially calcium scoring, may also be ordered based on your risk factors for heart disease, even if you don’t have symptoms.
What Is a Calcium Score?
A radiologist calculates your calcium score from the scan, and your doctor uses that number to guide your care. If your score is zero, the scan didn’t find calcium in your arteries, which suggests you have a low short-term risk of a heart attack.
Higher calcium scores show more plaque buildup and a greater risk of heart disease. Your doctor can use your score to decide whether you need lifestyle changes or more testing.
What Are the Most Common Reasons for a Spine CT Scan?
A spine CT can be performed on three different sections of the spine:
- The cervical spine (neck)
- The thoracic spine (mid-back)
- The lumbar spine (lower back)
Your doctor may order a spine CT scan if you have symptoms such as:
- Neck or back pain
- Weakness in your arms or legs
- Numbness or tingling
- Pain that spreads into an arm or leg
- Trouble walking or moving normally
Doctors order a scan of the spine to:
- Assess injuries after trauma, such as fractures or dislocations of the vertebrae, which are the small bones that stack together to form your spine
- Detect tumors or cancer that has spread to the bones of the spine
- Detect herniated discs, which occur when the soft cushion between vertebrae slips out of place and presses on nerves
- Check for spinal cord compression, a condition where the spinal cord is being squeezed and may cause pain, weakness or numbness
- Evaluate scar tissue that may have formed after back surgery
A spinal CT scan can be helpful if you cannot safely have an MRI. This may happen if you have certain devices or metal in your body that could affect the scan.
What Are the Most Common Reasons for a CT Scan of Bones or Joints?
A CT scan of the bones gives your doctor more detail about your bone structure than a standard X-ray can provide. You may need a bone or joint CT scan if you have symptoms such as:
- Pain in a bone or joint
- Swelling or bruising after an injury
- Trouble moving the area normally
- Difficulty putting weight on the joint
- A visible change in the shape or position of the bone or joint
Your doctor may recommend a bone or joint CT scan when:
- You get an unclear result from an X-ray or physical exam
- A suspected fracture is hard to see on a regular X-ray, such as a small crack or stress fracture
- A bone lesion or abnormal growth needs a closer look
- Joint damage from an injury needs to be mapped out before treatment or surgery
In some parts of the body, many bones and joints sit close together, which can make it harder to tell exactly where the problem is on a standard X-ray. A CT scan gives your doctor a more detailed view of the area, which can help show which bone or joint is affected and how far the damage extends.
How To Schedule a CT Scan
If your doctor has recommended a CT scan, American Health Imaging offers a range of CT exams to help evaluate pain, injuries, and other symptoms affecting the head, chest, abdomen, spine, bones, and more. Whether your doctor is checking for the cause of ongoing discomfort or looking more closely at an abnormal finding, getting the right scan can help move your care forward.
Your exam will be read by a board-certified, subspecialized radiologist, and we offer same-day and next-day appointments at convenient locations across Georgia, Alabama, Texas, South Carolina, and Florida. Talk to your doctor about imaging and schedule your CT scan with American Health Imaging today.