Tuesday, January 03, 2006

I have a CT Scan tomorrow. I have to drink Barium this evening and tomorrow before the test. It's no so bad. My dad told me not to worry. My mom told me to carry an icon in my pocket. I told this to my sister and she laughed. Of course, she said.

from the site Radiology Info

What is CT Scanning of the Body?

CT (computed tomography), sometimes called CAT scan, uses special x-ray equipment to obtain image data from different angles around the body and then uses computer processing of the information to show a cross-section of body tissues and organs.

CT imaging is particularly useful because it can show several types of tissue—lung, bone, soft tissue and blood vessels—with great clarity. Using specialized equipment and expertise to create and interpret CT scans of the body, radiologists can more easily diagnose problems such as cancers, cardiovascular disease, infectious disease, trauma and musculoskeletal disorders.

How does the procedure work?

CAT scan: liver
CT scan showing the liver.

CAT scan: abdominal
CT slice through the mid abdomen showing multiple normal appearing organs which are labeled.

CAT scan: appendix
CT scan of a normal appendix in the right lower abdomen. The appendix normally connects with the right colon and contains air- this appears black on the scan. Air in the appendix excludes appendicitis since this means that the appendix is not obstructed or inflamed.

Appendicitis: The appendix is distended and inflamed. In this patient the appendix has not yet ruptured.

In many ways CT scanning works very much like other x-ray examinations. Very small, controlled amounts of x-ray radiation are passed through the body and different tissues absorb radiation at different rates. With plain radiology, an image of the inside of the body is captured when special film is exposed to the absorbed x-rays. With CT the film is replaced by an array of detectors that measure the x-ray profile.

Inside the CT scanner is a rotating gantry that has an x-ray tube mounted on one side and an arc-shaped detector mounted on the opposite side. An x-ray beam is emitted in a fan shape as the rotating frame spins the x-ray tube and detector around the patient. Each time the x-ray tube and detector make a 360-degree rotation and the x-ray passes through the patient's body, the image of a thin section is acquired. During each rotation the detector records about 1,000 images (profiles) of the expanded x-ray beam. Each profile is then reconstructed by a dedicated computer into a two-dimensional image of the section that was scanned. Multiple computers are typically used to control the entire CT system.

You might think of it as a loaf of bread cut into thin slices. When the image slices are reassembled by computer, the result is a very detailed, multidimensional view of the body's interior.

A relatively new technique, spiral (helical) CT has improved the accuracy of CT for many diseases. A new vascular imaging technique, called spiral CT angiography, is noninvasive and less expensive than conventional angiography and allows doctors to see blood vessels without the need for more invasive procedures.

The term "spiral CT" comes from the shape of the path taken by the x-ray beam during scanning. The examination table advances at a constant rate through the scanner gantry while the x-ray tube rotates continuously around the patient, tracing a spiral path through the patient. This spiral path gathers continuous data with no gaps between images.

With spiral CT, refinements in detector technology support faster, higher-quality image acquisition with less radiation exposure. The current spiral CT scans are called multidetector CT and are most commonly four- or 16-slice systems. CT scanners with 64 detectors are now available. These instruments should provide either faster scanning or higher resolution images. Using 16-slice scanner systems the radiologist can acquire 32 image slices per second. A spiral scan can usually be obtained during a single breath hold. This allows scanning of the chest or abdomen in 10 seconds or less. Such speed is beneficial in all patients but especially in elderly, pediatric or critically ill patients, populations in whom the length of scanning was often problematic. The multidetector CT also allows applications like CT angiography to be more successful.

With conventional CT, small lesions may go undetected when a patient breathes differently on consecutive scans because lesions may be missed by unequal spacing between scans. The speed of spiral scanning and a single breath hold increase the rate of lesion detection.


Blogger zipyflavor said...

Personally, I didnt mind the barium. It wasnt a walk in the park, but I thought it was going to be much worse. Like a really think paste with a hint of gatorade.

Hey, we'll both be in the hospital, although mine is for something totally lame. I'll be thinking of you!

Wednesday, January 04, 2006 9:59:00 AM  

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