Term: Computerized Tomography


Description:

A computerized Tomography or CT Scan, is a medical imaging device that uses x-rays to capture images in slices of selected pieces of your body. Digital geometry processing is used to generate a three dimensional image of the inside of an object from a large series of two-dimensional X-ray images taken around a single axis of rotation. This helps to capture any defects in organs or tissue’s that can not be seen from looking at the organ or tissue from the outside. In this technology usually the imaging device moves around the body to get different views of organ or tissue. This helps people from being exposed to a less amount of radiation compared to a normal x-ray.

After a scan is complete and all images have been taken, the image slices are then put together to form a three dimensional figure. This three dimensional figure allows a doctor to view a organ or tissue from the inside instead of the outside. For example if CT scan was taken of your head, you can view the brain from the center out instead from the outside in. This allows doctors to view organs in much more detail to isolate a problem more quickly and correctly.

A CT scan is used these days to locate and identify tumors. Also when given a CT scan patient's are injected with a chemically colored dye into the blood stream which causes your blood in your circulatory system to glow when images are taken. This helps in isolating blood clots or clogged blood vessels.

Surface Rendering:

A threshold value of radiodensity is set by the operator (e.g., a level that corresponds to bone). From this, a three-dimensional model can be constructed using edge detection image processing algorithms and displayed on screen. Multiple models can be constructed from various different thresholds, allowing different colors to represent each anatomical component such as bone, muscle, and cartilage. However, the interior structure of each element is not visible in this mode of operation.

Volume Rendering:
Surface rendering is limited in that it will display only surfaces that meet a threshold density, and will display only the surface that is closest to the imaginary viewer. In volume rendering, transparency and colors are used to allow a better representation of the volume to be shown in a single image. For example, the bones of the pelvis could be displayed as semi-transparent, so that, even at an oblique angle, one part of the image does not conceal another.

Application:


Used in Hospitals, Cancer treatment

Web Resources/References:


-http://www.umm.edu/radiology/ct.htm
-http://www.cancer.gov/cancertopics/factsheet/Detection/CT
http://en.wikipedia.org/wiki/Computed_tomography

Related Terminology:


CT Scan
Tomography
Tomosynthesis
Electron beam CT
Dynamic volume CT

Graphics:

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