A computed tomography (CT) scan uses X-rays and digital geometry processing to produce cross-sectional images of the inside of the body. During a CT scan, an X-ray tube rotates around the body and takes pictures from different angles, which are processed by a computer to generate 2D and 3D images of tissues and organs. CT scans can identify problems like traumatic injuries, tumors, and infections by creating detailed images of internal structures like the head, chest, abdomen, arms, and legs. Contrast material may sometimes be used to better visualize certain areas.

1. Computed Tomography
Presenter : Khizra Samad

2. • Computed tomography, also known as computed tomography (CT
scan)
• It is a medical imaging procedure that uses computer-processed Xrays to produce tomographic images or 'slices' of specific areas of
the body.
• The CT scanner uses digital geometry processing to generate a 3dimensional (3-D) image of the inside of an object. The 3-D image is
made after many 2-dimensional (2-D) X-ray images are taken
around a single axis of rotation - in other words, many pictures of
the same area are taken from many angles and then placed
together to produce a 3-D image.

3. Cont..
• CAT scans take the idea of conventional X-ray imaging to a
new level. Instead of finding the outline of bones and organs,
a CAT scan machine forms a full three-dimensional computer
model of a patient's insides. Doctors can even examine the
body one narrow slice at a time to pinpoint specific areas.
• CT scans are performed to analyze the internal structures of
various parts of the body. This includes the head, where
traumatic injuries, (such as blood clots or skull fractures),
tumors, and infections can be identified

4. Image of the abdomen
Image of conventional chest

5. Working
• During the test, you 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.
• Inside the CT scanner there is an X-ray detector which can see
hundreds of different levels of density. It can see tissues inside a
solid organ. This data is transmitted to a computer, which builds up
a 3-D cross-sectional picture of the part of the body and displays it
on the screen.
• 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.
For some types of CT scans you drink the dye. The dye makes
structures and organs easier to see on the CT pictures.

7. Uses:
CT scans are used to study areas of the body and the arms or legs.
• Chest (thorax): A CT scan of the chest can look for problems with the
lungs, heart, esophagus, the major blood vessel (aorta), or the tissues
in the center of the chest. It also can be used to see if cancer has
spread into the chest from another area of the body.
• Abdomen. A CT scan of the abdomen can find cysts, abscesses,
infection, tumors, an aneurysm, enlarged lymph nodes, foreign
objects, bleeding in the belly, diverticulitis, inflammatory bowel
disease, and appendicitis.
• Urinary tract. A CT scan of the kidneys, ureters, and bladder is called a
CT KUB or CT urogram. This type of scan can find kidney stones,
bladder stones, or blockage of the urinary tract.

8. Cont..
• Gallbladder and bile ducts : A CT scan can be used to
check for blockage ofther bile ducts. Gallstones occasionally show up on
a CT scan. But other tests, such as ultrasound, usually are used to find
problems with the gallbladder and bile ducts
• Adrenal glands. A CT scan can find tumors or enlarged adrenal
glands.
• Arm or leg. A CT scan can look for problems of the arms or legs,
including the shoulder, elbow, wrist, hand, hip, knee, ankle, or foot.
• A CT scan may be used to make sure a procedure is done correctly.
For example, the doctor may use CT to guide a needle during a tissue
biopsy or to guide the proper placement of a needle to drain an
abscess.

9. Risks
Risks of CT scans include:
• Allergic reaction to contrast dye
• Being exposed to radiation

10. Reference
• http://en.wikipedia.org/wiki/X-ray_computed_tomography
• http://www.nlm.nih.gov/medlineplus/ency/article/003330.ht
m
• http://www.fda.gov/RadiationEmittingProducts/RadiationEmittingProductsandProcedures/
MedicalImaging/MedicalX-Rays/ucm115317.htm
• http://www.cancer.gov/cancertopics/factsheet/detection/CT