What is CT Scan -­ I

CT scanning – sometimes called CAT scanning – is a noninvasive medical test that helps physicians diagnose and treat medical conditions. CT scanning combines special x-ray equipment with sophisticated computers to produce multiple images or pictures of the inside of the body. These cross-sectional images of the area being studied can then be examined on a computer monitor, printed or transferred to a CD.

What is CT Scan ‐ II

CT scans of internal organs, bones, soft tissue and blood vessels provide greater clarity and reveal more details than regular x-ray exams. Using a variety of techniques, including adjusting the radiation dose based on patient size and new software technology, the amount of radiation needed to perform a chest CT scan can be significantly reduced. A low-dose chest CT produces images of sufficient image quality to detect many lung diseases and abnormalities using up to 65 percent less ionizing radiation than a conventional chest CT scan. This is especially true for detecting and following lung cancer.

 Preparation ‐ I

You should wear comfortable, loose-fitting clothing to your exam. You may be given a gown to wear during the procedure. Metal objects including jewelry, eyeglasses, dentures and hairpins may affect the CT images and should be left at home or removed prior to your exam. You may be asked not to eat or drink anything for several hours beforehand, especially if a contrast material will be used in your exam.

Preparation -­ II

You should inform your physician of any medications you are taking and if you have any allergies. If you have a known allergy to contrast material, or ‘dye,’ . Also inform your doctor of any recent illnesses or other medical conditions, and if you have a history of heart disease, asthma, diabetes, kidney disease or thyroid problems. Any of these conditions may increase the risk of an unusual adverse effect. Women should always inform their physician and the CT technologist if there is any possibility that they are pregnant.


The CT scanner is typically a large, box like machine with a hole, or short tunnel, in the center. You will lie on a narrow examination table that slides into and out of this tunnel. Rotating around you, the x-ray tube and electronic x-ray detectors are located opposite each other in a ring, called a gantry. The computer workstation that processes the imaging information is located in a separate room, where the technologist operates the scanner and monitors your examination.

Procedure -­ I

The technologist begins by positioning you on the CT examination table, usually lying flat on your back or possibly on your side or on your stomach. For children who cannot hold still for the examination, sedation may be needed. Motion will degrade the quality of the examination the same way that it affects photographs. If contrast material is used, it will be swallowed, injected through an intravenous line (IV) or administered by enema, depending on the type of examination.

Procedure – ­II

Next, the table will move quickly through the scanner to determine the correct starting position for the scans. Then, the table will move slowly through the machine as the actual CT scanning is performed. You may be asked to hold your breath during the scanning. Any motion, whether breathing or body movements, can lead to artifacts on the images. This is similar to the blurring seen on a photograph taken of a moving object. When the examination is completed, you will be asked to wait until the technologist verifies that the images are of high enough quality for accurate interpretation.

Experience during and after the procedure

CT exams are generally painless, fast and easy. With helical CT, the amount of time that the patient needs to lie still is reduced. If you have a hard time staying still, are claustrophobic or have chronic pain, you may
find a CT exam to be stressful. The technologist or nurse, under the direction of a physician, may offer you a mild sedative to help you tolerate the CT scanning procedure.

Benefits of CT Scan -­ I

CT scanning is painless, noninvasive and accurate. A major advantage of CT is its ability to image bone, soft tissue and blood vessels all at the same time. CT examinations are fast and simple; in emergency cases, they can reveal internal injuries and bleeding quickly enough to help save lives.

Benefits of CT Scan -­ II

CT has been shown to be a cost-effective imaging tool for a wide range of clinical problems. CT is less sensitive to patient movement than MRI. CT can be performed if you have an implanted medical device of any kind, unlike MRI. CT imaging provides real-time imaging, making it a good tool for guiding minimally invasive procedures such as needle biopsies and needle aspirations of many areas of the body, particularly the lungs, abdomen, pelvis and bones.

Benefits of CT Scan -­ III

A diagnosis determined by CT scanning may eliminate the need for exploratory surgery and surgical biopsy. No radiation remains in a patient’s body after a CT examination. X-rays used in CT scans usually have no immediate side effects.

Risks of CT Scan -­ I

The risk of serious allergic reaction to contrast materials that contain iodine is extremely rare. There is always a slight chance of cancer from excessive exposure to radiation. However, the benefit of an accurate diagnosis far outweighs the risk. CT scanning is, in general, not recommended for pregnant women unless medically necessary because of potential risk to the baby.

Risks of CT Scan – ­II

Nursing mothers should wait for 24 hours after contrast material injection before resuming breast-feeding. Because children are more sensitive to radiation, they should have a CT study only if it is essential for making a diagnosis and should not have repeated CT studies unless absolutely necessary.