Computed Tomography (CT), developed by Sir Godfrey Hounsfield in 1970, is a medical imaging technique that creates 3D images from 2D X-ray images using digital geometry processing. The components of a CT scanner include a gantry, X-ray tube, detector, and control console, utilizing various scanning techniques such as axial and volumetric CT. CT imaging provides critical insights into internal body structures, aiding in medical assessments for trauma, tumors, and vascular status.

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