CT (Computed Tomography) scan is a diagnostic test involving use of X-rays to detect any abnormalities which have taken place within the human body. This test is more advanced than the ordinary X-ray test.
While a plain X-ray film will show only bones clearly, CT scan helps in visualizing soft tissues, blood vessels, solid organs like lungs, liver, brain with great clarity. CT scan shows cross sectional images of the person’s internal organs.
Types of CT Scan:
Depending on the organs which are to be studied, CT Scan can be of the following types:
- CT Scan Brain: The brain along with all its parts is studied in great detail in this procedure. X-rays are focused on the brain to study the tissue well. Brain, medulla, cerebellum, cranial blood vessels, skull bones can be studied in great detail during this procedure. Cerebral aneurysm, cerebral hemorrhage, brain cancer, cavernous sinus thrombosis, hydrocephalus, are some of the indications for which CT scan brain may be required. The procedure is also known as CT scan head/ CT scan skull.
- CT Scan Neck: Many important structures like spinal cord, thyroid gland, esophagus, larynx lie in the neck. CT scan of neck can be done if any of these structures is to be studied for abnormal changes. Esophageal varices, trachea stenosis, thyroid nodules are some conditions which can be assessed via CT scan of the neck.
- CT Scan Chest: Chest cavity houses the most important organs in the human body viz., lungs and heart. CT scan of the chest helps in studying these organs in great detail. Health conditions like T.B., pulmonary embolism, pulmonary edema, lung cancer, mediastinal cancer, cardiomegaly, can be diagnosed using this procedure. CT scan in women may be helpful in diagnosing breast disorders.
- CT Scan of Spine: Spinal cord is a very important organ connecting brain to the rest of the body. It is enclosed and protected within the vertebral column. CT scan of spine helps in studying any abnormal changes in the vertebral column or spine. Inter vertebral disc herniation, spinal tumors, inter vertebral cartilage degeneration are some of the health conditions which can be diagnosed via CT scan spine.
- CT Scan Abdomen: Abdominal cavity encloses almost all organs which form the digestive system. CT of the abdomen helps in visualizing and diagnosing disorders of various abdominal organs like liver, intestines, pancreas, spleen etc. It also helps in diagnosing a condition known as peritonitis.
- CT Scan Pelvis: Pelvic cavity lies below the abdominal cavity. Reproductive organs in men as well as women are located in pelvic cavity. Pelvic CT scan helps in visualizing reproductive as well as other pelvic organs. In women, this investigations helps in diagnosing disorders of uterus, vagina, cervix, ovaries. Men having prostate troubles are advised to undergo CT scan of pelvis. Urinary disorders like cystitis, bladder cancer, urethritis can also be detected by doing a pelvic scan.
- CT Scan Limbs: CT scan of arms and legs is done in those patients who have suffered from trauma to their limbs. Swelling, infection, pain of unknown origin affecting the arms or legs can be assessed using CT scan.
- CT Angiography: This is the study of arteries and veins using CT scan. It is useful in health conditions like deep vein thrombosis, pulmonary embolism, aneurysm, varicose veins etc.
- Whole body CT scan: Whole body CT scan can be done when patients present with multi-systemic disorders. When a number of organs or systems in the body need to be studied, this investigation provides extremely good results.
Depending on the usage of contrast dye, CT scan could be of 2 types:
- CT Scan with contrast: At times, CT scan requires the patient to be injected with a dye. A contrast liquid dye is injected into the person’s veins from where it circulates through blood stream to all body parts. It provides better clarity during CT scan and may be used when minute changes in body tissue or very small tissues are to be studied.
- CT Scan without contrast: Contrast dye is not always mandatory to perform CT Scan. Sometimes the doctor may proceed to perform the scan without using a dye. For CT angiography, contrast is mandatory, as images cannot be visualized clearly without the dye.
CT Scan Machine:
CT scan machine or a CT scanner is a large rectangular box like structure fitted with a wide ring. The box carries the electronic panel of the machine, whereas the X-ray beams are emitted out of the ring. A sliding bed is attached to the machine. Once the patient lies on the bed, the bed slides within the ring. The speed at which the machine slides can be adjusted depending on the doctor’s analysis.
The ring like structure carries X-ray tube and X-ray detector. Rays emitting from the tube can be focused on that part of patient’s body which is to be studied. The machine scans the patient’s internal organs and creates images that can be visualized on a computer screen. A computer panel located in another room controls the functioning of the CT scanner machine.
Images generated by the machine can be printed on a special paper and used by the doctor to study the patient’s health condition.
When can CT Scan be done?
Health conditions like cancer, swellings, tumors and growth, traumatic deformities advocate the necessity of CT scan. It is indicated in the following cases:
- Primary Investigation: CT scan may be a first line investigation in many cases of complicated health disorders. Cancers, hemorrhages, tumors, traumatic impact, aneurysms can be detected by making patients undergo CT scan.
- Secondary Investigation: Patients having known health conditions may be advised to undergo CT scan if primary investigations like X-ray, USG, blood tests do not yield accurate diagnosis.
- Follow up: To assess progress of patients during medical treatment of their health condition, diagnostic investigations need to be done. CT scan can be utilized as a follow up investigation in such patients to see whether they are benefiting from the treatment they receive and to what extent.
- Guidance tool: Other investigative or therapeutic procedures like tissue biopsy and other minimally invasive methods may be performed using CT scan as a guidance method. This helps the doctor to see internal organs clearly while performing the particular procedure.
Contra-indications of CT Scan:
CT scan machine emits X-rays of varying intensity which helps in creating images of patient’s internal organs. Because of long term side effects due to chronic exposure to X-rays, certain group of patients are not suitable candidates for CT scan. The same may not be applicable to plain X-rays as the intensity of radiation is not as strong as what is used in CT scan.
Following are the factors which are contraindications for CT scan:
- Pediatric Patients: Children continue to grow physically till the age of 18 years. Exposure to strong X-ray beams may be a retarding factor for their growth. Therefore it is not advisable for children to be exposed to CT scanner.
- Pregnant ladies: Exposure to X-ray beams can lead to harmful effects on the growing fetus. Hence, pregnant ladies are not advised to undergo CT scan as far as possible.
- Cancer patients: Cancer cells are known to multiply significantly under constant effect of X-ray radiation. Hence, recurrent CT scans are inadvisable for cancer patients. If they are required, special precautions need to be taken before and after the procedure.
- Allergy to contrast dye: Patients with kidney disorders, liver disorders, hypertension could develop allergic reaction to the contrast dye used for CT scan. In such patients, immense care has to be taken while administering the dye. Or the scan could be performed without contrast dye.
Cost of CT Scan:
Cost of CT scan procedure at diagnostic centers all across India ranges from INR 2,000 to INR 12,000. Cost of CT scan in India depends upon the type of scan, patient’s health conditions, usage of contrast dye etc.
CT scan is an advanced diagnostic feature involving use of radiation beams. The contraindications of CT scan have been discussed in the article. Patients are advised not to undergo the scan without a doctor’s advise and prescription. All instructions provided to patients regarding the procedure should be followed well for a successful procedure and accurate results.