A diagnostic method that obtains cross-sectional images of the body within seconds using X-rays and computer technology. It provides rapid information in emergencies, hemorrhage, trauma and organ disease.
Indication
- Emergency assessment in head trauma, brain hemorrhage or suspected stroke
- Examination of lungs and great vessels in chest pain, shortness of breath or hemoptysis (including pulmonary embolism)
- Suspicion of acute appendicitis, kidney stone, intestinal obstruction in abdominal pain
- Comprehensive evaluation in multi-region trauma such as traffic accidents and falls
- Cross-sectional imaging in cancer diagnosis, staging and treatment response follow-up
- Preoperative planning and guidance for interventional procedures (CT-guided biopsy)
- Assessment of vascular stenosis and dilation (aneurysm, dissection) with CT angiography
Preparation
- For abdominal CT, fasting for 4-6 hours before the scan and drinking oral contrast in the last 1-2 hours is generally recommended
- If contrast material is to be administered, kidney function (creatinine/eGFR) is checked and iodine allergy is questioned
- In diabetic patients taking metformin-containing medications, a 48-hour pause may be required after contrast
- Pregnancy and breastfeeding status must be reported; if possible, alternatives without ionizing radiation are considered
- Metal items, jewelry and bras are removed from the scan area
How it's performed
- The patient lies on the table; depending on the area, head, arms or legs are positioned accordingly
- The table moves through the ring-shaped device (gantry); since the device is open and short, claustrophobia is rare
- In some scans, breath-holding instructions are given (especially in lung and abdominal exams)
- If needed, iodinated contrast material is administered through a vein; a sensation of warmth and a temporary metallic taste may occur
- The actual scan is generally completed within seconds to a few minutes
- Images are evaluated in multiple planes and reported by a radiologist
Post-procedure
- There are no special restrictions after the scan; daily life can resume immediately
- If contrast was given, drinking plenty of water is recommended to facilitate excretion
- Observation for 1-2 hours may be required in case of delayed allergic reactions
- Results are usually ready the same day or within 1-2 business days
- Additional imaging, biopsy or treatment plan is arranged when findings require it
Risks
- CT involves ionizing X-rays; the dose is kept as low as reasonably achievable, and unjustified repetitions are avoided
- It is not preferred during pregnancy unless there is a clear indication, due to the radiation effect on the fetus
- Iodinated contrast may rarely cause allergic reactions and may damage the kidneys in advanced renal failure
- There may be a risk of lactic acidosis in patients with advanced renal failure who take metformin; physician advice should be followed
- The cumulative radiation dose is considered in children and in cases requiring frequent repetition
FAQ
Should I have a CT or an MRI?
The decision depends on the physician's assessment. CT provides quick results in emergencies, hemorrhage and bone examination. MRI is superior in soft tissue detail and does not use radiation. The two methods are not interchangeable but answer different clinical questions.
Is the radiation in CT harmful?
The X-ray dose used in CT is kept as low as possible in modern devices. When medically justified, the benefit outweighs the risk. In children and pregnant women, alternative methods are considered when possible.
What will I feel when contrast is given?
When contrast is administered intravenously, a sensation of warmth in the body, metallic taste in the mouth, or feeling of needing to urinate may occur; these are temporary. Severe allergic reactions are rare; a history of allergies is always questioned beforehand.
I am pregnant, can I have a CT?
During pregnancy, CT is performed only when vitally necessary, with the abdominal area shielded as much as possible. When possible, methods without radiation such as ultrasound or MRI are preferred.
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