The CT medical abbreviation most often means computed tomography, an imaging test that uses X-rays and a computer to build thin cross section pictures of the body. Many people still call it a CAT scan, from the older name computed axial tomography.
CT is short enough that other specialties use it too. On a surgical floor it can mean chest tube, in a sexual health clinic it can mean the infection Chlamydia trachomatis, and in hospital team names it often means cardiothoracic. Surrounding words almost always make the meaning plain. This page starts with the scan, then turns to the other meanings and the clues that separate them.
At a glance
Stands for
Computed tomography (most common)Other meanings
Chest tube; Chlamydia trachomatis; cardiothoracic (surgery)Also called
CAT scan, computed axial tomographyWritten as
CT, CT scan, CT w/ contrast, CT w/o contrastDo not confuse with
Where you see it
Radiology orders and reports, emergency notes, surgical and clinic notes
What the CT medical abbreviation computed tomography means
During a CT scan you lie on a table that slides through a large ring. Inside the ring, an X-ray tube spins around you while detectors on the other side record how much of the beam passes through. A computer turns those readings into slices, like the pages of a book, that can be stacked and viewed from any angle. The name says as much: tomo comes from the Greek for slice, and graphy means recording.
Compared with a single X-ray, a CT shows soft tissue, organs, bleeding and bone in far more detail. It is fast, often finished in minutes, which is why emergency departments rely on it for head injuries, strokes, belly pain and trauma.
Reading a CT scan order
A CT order names the body part, whether contrast dye is used, and the reason for the test. Here is a typical line taken apart.
| Part | Meaning |
|---|---|
| CT | Computed tomography |
| abdomen/pelvis | The area to be scanned, belly and pelvis together |
| with IV contrast | Iodine dye given through a vein to make vessels and organs stand out |
| r/o appendicitis | The reason: check whether the appendix is inflamed |
Contrast can also be swallowed for bowel studies. When no dye is used, the order says without contrast, or w/o. A head CT is so common that it has its own shorthand, CTH, and a scan focused on blood vessels is a CTA.
Other meanings of CT and how to spot them
| Meaning | Where you see it | Clue in the note |
|---|---|---|
| Computed tomography | Radiology, emergency, almost every specialty | Body part, contrast, scan, findings |
| Chest tube | Surgery, ICU, trauma | Output in mL, suction, water seal, side |
| Chlamydia trachomatis | Sexual health, primary care, OB | GC/CT, NAAT, swab, urine test |
| Cardiothoracic | Surgery team names | CT surgery, CT ICU, CT surgeon |
An ICU flowsheet note: "L CT to -20 suction, 150 mL serosanguineous over shift, no air leak." Here CT is a chest tube on the left side, and the nurse is recording drainage.
A clinic result line: "GC/CT NAAT negative." This reads as a negative swab or urine test for gonorrhea and chlamydia, not a scan.
Radiation, contrast and safety
Compared with a single plain film, CT gives a larger radiation dose, though the dose depends on the body part and the machine. Imaging teams try to use the lowest dose that still answers the question, and they take special care with children and pregnancy. If you might be pregnant, tell the staff before the scan.
Iodine contrast is safe for most people, but the team will ask about past reactions to dye, kidney problems, and certain diabetes medicines such as metformin, which some centers pause around a contrast scan. Kidney function is often checked first with a GFR result. Follow the instructions your imaging center gives you.
CT scan medical abbreviation versus MRI and X-ray
Patients often ask why one test was chosen over another. A plain X-ray, such as a CXR, is quick and low dose but flat. CT gives cross sections with strong detail of bone, lungs and bleeding, and it is fast. MRI uses a magnet and radio waves instead of X-rays, takes longer, and is often better for the brain, spinal cord, joints and some soft tissues. Ultrasound uses sound waves and is common for the gallbladder, pregnancy and blood vessels in the legs.
For more scan and lab shorthand, browse the tests and scans hub.
What to ask before a CT
- Will I get contrast, and do I need to stop eating beforehand?
- Should I take my usual medicines that day?
- How long will the scan take, and when will results be ready?
- Who will explain the report to me?
A CT report uses technical language meant for the ordering clinician, so let the doctor or advanced practice provider who ordered it put the findings in context.
Frequently asked questions
What does CT stand for in medical terms?
Most often it stands for computed tomography, the cross section imaging test. In other settings it can mean chest tube, Chlamydia trachomatis or cardiothoracic. The surrounding words usually make the meaning clear.
Is a CT scan the same as a CAT scan?
Yes. CAT stands for computed axial tomography, the older name. Today most staff just say CT.
What does CT with contrast mean?
It means a dye is used to make blood vessels and organs show up more clearly. The dye is usually given through an IV, and sometimes it is swallowed.
What does GC/CT mean on a lab result?
GC stands for gonorrhea and CT stands for Chlamydia trachomatis. The line reports a test for those two infections, usually from a urine sample or swab.
Does a CT scan hurt?
The scan itself is painless. You lie still for a short time, and the only discomfort is usually the IV needle if contrast is used.