it describe, what is computer tomography , different component of the machine used and how the image is created using x- rays.

1. COMPUTER TOMOGRAPHY
BY -: Lovnish Thakur (IBT -1ST Semester)
Enrollment N o. -: ASU2014010100099
From -: school of bioscience

2. Computer tomography (CT), originally known as computed
axial tomography (CAT or CT scan) and body section
rentenography.
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.
The word "tomography" is derived from the Greek tomos (slice)
and graphein (to write). CT produces a volume of data which
can be manipulated, through a process known as windowing, in
order to demonstrate various structures based on their ability to
block the X-ray beam.

3. CT: The beginning
 CT founded in 1970 by Sir Godfrey Hounsfield
 first applications were in neuroradiology.

4. CT Scanner
Used to determine
 extent of trauma
 location and type
of tumors
 status of blood
vessels
-pre surgical planning

5. Basic CT scanner components
 Gantry
 X-Ray Tube
 Detector
 Control Console

6. Gantry
. The CT scanner gantry is a moveable frame that
contains the x-ray tube, including: collimators
and filters, detectors, data acquisition system,
rotational components including slip ring systems,
and all associated
electronics such as
CT scanner gantry
angulation motors
& positioning laser
lights.

8. Capture energy that has not been attenuated
by the patient.

12. Digital projection
AP, PA, Lat or Oblique projection
Conventional CT
-Axial
 Volumetric CT
- Helical or spiral CT

13. Digital Projection
X-ray tube and detector
remain stationary
 Patient table moves
continuously
Produces an image
covering a range of
anatomy
 Image used to
determine scan location

14. Axial CT
 X-ray tube and detector rotate 360°
 Patient table is stationary
 Produces one cross-sectional image
 Once this is complete patient is moved to next
position.

15. X-ray tube and detector rotate 360°
Patient table moves continuously
 Produces a helix of image information

16. Attenuation
 X-ray beam passes through patient
 Each structure attenuates X-ray beam differently
 According to individual densities
 Radiation received by detector varies according to
these densities

17. Transferred from detector to CT computer
(A to D converter)
Reconstructed by computer into a cross-sectional image
Displayed on screen
Each pixel displayed on monitor has varying brightness
The greater the attenuation, the brighter the pixel
The less attenuation, the darker the pixel

18. Density information
 Density values correspond to
a range of numbers
 Hounsfield scale

20. Window width
Determines range of CT numbers displayed on an
image
-:Values above this range = white
-:Values below this range = black
Window level
 Sets the center CT number displayed on the
monitor

21. CT image quality
 Spatial resolution
 Ability to resolve small objects in an image.
 Contrast resolution
 Ability to differentiate small density differences in an
image.
 Post Processing Options
• Visualization of vasculature in relation to pathology.
• Show course of vessels.
• Define vascular stricture.

22. CT SCANNER
Thus provide a window into the
body.

23. SOME OF IMAGE FORMED BY CT SCAN

24. THANK YOU