CT scan

A computed tomography (CT) scan uses x-ray technology to produce computer-generated images of structures inside your body. Like x-rays, CT scans use ionizing radiation to capture the images. Because they are three-dimensional (3D), CT scans provide much more detail than typical x-rays.

CT scans are useful for detecting injuries, cancer, cardiovascular disease, and many other conditions. At Penn Medicine, we are a nationally accredited provider of imaging services, including CT scans. Our skilled team of experts uses advanced imaging technology to diagnose diseases and start planning treatment.

A CT scanner rotates around your body and takes multiple pictures from different angles. The pictures are 2D (flat), cross-sectional images called slices. CT scanners take different numbers of slices, ranging from one to 640. In general, the higher the slice count the faster and more detailed the scan.

A computer takes all the slices and stacks them into a 3D image of the structure or organ being examined, a bit like a 3D printer. A radiologist may evaluate the 2D slices or the 3D images.

We use CT technology to evaluate many types of diseases and injuries in the head, abdomen, chest, pelvis, spine, and blood vessels. It can be combined with other diagnostic techniques for greater detail and accuracy. Surgeons and radiologists also use CT scans to guide and plan procedures and treatments.

Since CT scans use ionizing radiation, bones and other dense structures absorb the radiation well and appear white in images. Less dense structures like your brain, blood vessels, or organs in your digestive tract don’t show up with as much contrast.

In these cases, we often do a CT scan with a contrast agent. A contrast agent is a substance that absorbs ionizing radiation and illuminates organs and tissues. We may give you the contrast agent by mouth or through a vein in your arm.

Common CT scans offered at Penn Medicine include:

• Calcium score test: assesses the coronary artery for risk of having a future heart attack
• Chest CT: diagnoses symptoms such as chest pain or coughing and helps us spot lung nodules or early-stage cancers
• CT angiography: uses contrast material to examine veins and arteries that supply blood to your heart, brain, kidneys, and other organs
• CT biopsy: guides a needle precisely using CT images when taking samples of abnormal tissue from lungs, lymph nodes, and other organs
• CT enterography: is tailored to assess the small bowel
• Heart CT: uses contrast dye to create detailed images of heart valves, chambers, and blood vessels such as the aorta and pulmonary veins
• Virtual colonoscopy (CT colonography): uses x-rays to examine the colon from outside the body instead of inserting a scope into the rectum
• PET/CT: combines CT technology with a PET scan to pinpoint molecular activity in the body, which helps identify diseases

We may recommend a CT scan to diagnose:

• Abdominal pain, intestinal blockages, or digestive diseases
• Benign (noncancerous) tumors and cancer
• Bone fractures and soft tissue injuries
• Head, brain, and spine conditions
• Traumatic injuries and internal bleeding
• Vascular diseases such as aneurysms and blood clots
• Other injuries and diseases in people who can’t have an MRI

Your scan may be done at a hospital, emergency room, or outpatient imaging facility. The test is painless and usually takes 10 to 15 minutes. Follow any instructions from your care team about how to prepare for the exam.

A CT technologist performs the scan, and a doctor who specializes in imaging, called a radiologist, reviews and interprets the images. When you arrive for the test, you’ll change into a hospital gown. If you need a contrast agent, you’ll be given it by mouth or through an IV in your arm. During the test, you’ll lie down on a comfortable table attached to a doughnut-shaped CT scanner.

Your technologist goes into another room and talks to you through an intercom. The table will slowly move inside the CT scanner, and an x-ray tube rotates around you. When the test is complete, the table will move out of the scanner.

Most people don’t need any recovery time after a CT scan. If you had a CT scan with contrast dye, we may monitor you after the scan to make sure you feel well enough to go home. Some people experience mild and temporary side effects from the contrast agent, such as headache, dizziness, nausea, or an allergic reaction.

CT scans use ionizing radiation, which can damage tissue inside your body. Radiation also slightly increases your risk of cancer, particularly if you need repeated scans during your life. However, a CT scan’s potential to detect serious or life-threatening injuries and illnesses far outweighs the risks. Tell your care team before a CT scan if you’re pregnant or think you may be pregnant. If you need a pelvic or abdominal scan, we may recommend a different type of imaging that doesn’t use radiation.

Effective treatment starts with an accurate diagnosis. At Penn Medicine, you’ll find advanced imaging technology and an experienced, highly trained team. Our experts work together to select the right tests and imaging exams for your needs.

We offer:

• Recognized expertise: We are fully accredited in computed tomography by the American College of Radiology. This seal of approval means our staff, equipment, and overall care meet rigorous quality and safety standards.
• State-of-the-art imaging equipment: Our sophisticated CT scanners allow us to tailor scan settings for every patient. This customization improves accuracy and image quality while minimizing radiation doses.
• Comfort and convenience: Our staff helps you feel at ease before, during, and after your exam. In addition, radiation technologists and radiologists work together to get clear scans the first time, which reduces repeat or unnecessary testing.