Computed tomography (CT scan) is a medical imaging procedure that utilizes computer-processed X-rays to create cross-sectional pictures of the body. These cross-sectional images are used for diagnostic and therapeutic purposes in various medical disciplines.
It is painless and non-invasive technique.
X-ray slice data is generated using an X-ray source that rotates around the object; X-ray sensors are positioned on the opposite side of the circle from the X-ray source.
The main reason why X-rays is used in diagnosis is because all substances and tissues differ in their ability to absorb X-rays. Some substances are more permeable to X-rays while some others impermeable. Owing to this difference, different tissues seem different when the X-ray film is developed.
CT produces a volume of data that can be manipulated, through a process known as "windowing", in order to demonstrate various bodily structures based on their ability to block the X-ray beam.
Dense tissues such as the bones appear white on a CT film while the soft tissues such as the brain or kidney appear gray. The cavities filled with air such as the lungs appear black.
Computed tomography (CT) scans help doctors detect everything from cancer to kidney stones.
A computed tomography (CT) scan uses X- rays to make detailed pictures of structures inside of the body.
During the test, patient will lie on a table that is attached to the CT scanner, which is a large doughnut-shaped machine. The CT scanner sends X-rays through the body area being studied. Each rotation of the scanner provides a picture of a thin slice of the organ or area. All of the pictures are saved as a group on a computer. They also can be printed.
In some cases, a dye called contrast material may be used. It may be put in a vein in your arm, or it may be placed into other parts of your body (such as the rectum or a joint) to see those areas better.
The dye makes structures and organs easier to see on the CT pictures.
A CT scan can be used to study all parts of your body, such as the chest, belly, pelvis, or an arm or leg. It can take pictures of body organs, such as the liver, pancreas , intestines , kidneys, bladder, adrenal glands , lungs , and heart . It also can study blood vessels, bones, and the spinal cord.
The CT scanner consists of an X-ray tube that rotates around your body. Patient will usually be moved continuously through this rotating beam. The rays will be analysed by a detector on the opposite side of your body.
The images produced by a CT scan are called tomograms and are more detailed than standard X-rays. A CT scan can produce images of structures inside the body including the internal organs, blood vessels, bones and tumours.
The scan is painless and will usually take 10 to 30 minutes, depending on the part of your body being scanned.
When CT scans are used
CT scans can be used to diagnose and monitor a variety of different health conditions including brain tumours, certain bone conditons and injuries to internal organs such as the kidneys, liver or spleen.
They are also often used to look inside the body before another procedure takes place, such as radiotherapy treatment or a biopsy (where a small tissue sample is taken so that it can be examined under a microscope).
Safety
CT scans are safe procedures and, in most cases, the benefits of having a scan outweigh any potential risks.
A CT scan does expose you to radiation. The amount is small and will not cause you any harm. However, CT scans are not recommended for pregnant women because there is a small risk that the X-rays that are used could harm the unborn baby.
Children are also more at risk than adults are from developing a build-up of radiation.
Since its introduction in the 1970s, CT has become an important tool in medical imaging to supplement X-rays and medical ultrasonography. It has more recently been used for preventive medicine or screening for disease.
Post by : Swadesh Baidya.
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