Computed tomography (CT) is a medical imaging method that creates 3D images of the body's internals using a series of X-ray images processed by advanced computer systems. The first CT scanner was developed in 1972, and the technology offers detailed images useful for diagnosing organ injuries and other conditions, albeit with certain risks such as radiation exposure and allergic reactions to contrast dyes. CT scans can be expensive and have limitations on the frequency of use, especially for pregnant women.

1. COMPUTED
TOMOGRAPHY

2. DEFINITION
Computer tomography (CT) is originally
known as “Computed Axial Tomography”, also
known as Body Section Retenography.
It is a medical imaging method employing
tomography where digital geometry processing
is used to generate a three-dimensional image
of the internals of an object from a large series
of two-dimensional X-ray images taken around
a single axis of rotation.

3. ILLUSTRATION OF A CT
SCANNER

4. HISTORY
The first commercially viable CT scanner was
invented in 1972 by Godfrey Newbold Hounsfield
in Hayes, England using X-rays.
The first scan was done in 1973, of the brain.
Physicist Allan Cormack also invented a similar
machine in the United States.
Both Cormack and Hounsfield were awarded
the Nobel Prize in 1979.

6. When X-rays are irradiated on the human body, some
of the rays are absorbed and some pass through the body
to produce an image.
In plain X-ray imaging, the film directly absorbs
penetrated X-rays.
In CAT scanning, an electronic device called a
"detector array" absorbs the penetrated X-rays, measures
the X-ray amount, and transmits the data to a computer
system.
A sophisticated computer system, in turn, calculates
and analyzes data from each detector in each level, and
finally reconstructs multiple, two-dimensional, cross-
sectional images.
HOW DOES IT WORKS?

7. DETECTOR ARRAY

8. CLASSIFICATION
Abdominal
Bone
Head
Vascular
The four classifications of the types
of scans are:

9. Depending on the type of scan, you may not
be allowed to eat/drink a few hours prior to
scan.
Wear comfortable clothing or a gown will be
provided.
All metal and electronic possessions that can
be removed must be removed.
Intravenous contrast (if necessary) is injected
into patient.
Patient is then asked to lay on the machine
platform and aligned.
PROCEDURE
INVOLVED

10. NAME SOURCE OF DATA
NAME SOURCE OF
DATA
Atom probe tomography Atom probe
Confocal tomography Laser
Electrical capacitance
tomography
Electron capacitance
Microwave tomography Microwave
Optical coherence tomography Interferometry
Ocean acoustic tomography Sonar
Zeeman Doppler imaging Zeeman effect
Optical projection tomography Optical microscope
Optical diffusion tomography Absorption of light
TYPES OF TOMOGRAPHY

11. ADVANTAGES
It emits a series of narrow beams through the
human body, producing more detail information
than standard single beam X-rays.
These are able to distinguish tissues inside a solid
organ.
It gives the detailed 3D images of various body
parts.
It is used to illustrate organ tear and organ injury
very quickly.

12. Iodine is the usual contrast dye. Some
patients are allergic to iodine and may
experience a reaction that may include
nausea, breathing difficulty or other
symptoms.
The amount of radiation used during a CT
procedure is considered minimal, therefore
the risk for radiation exposure is very low.
Radiation exposure during pregnancy may
lead to birth defects.
RISKS ASSOCIATED

13. Cost is high.
Restriction on number of exams in a given
period of time.
Women who are pregnant, generally are
discouraged from having a CAT scan performed.
Risk of getting cancer.
Intravenous or oral contrast can be
uncomfortable.
Decrease the time needed for scan/Decrease the
amount of radiation required for scan.
LIMITATIONS