1. Computed Tomography by Ms. Nouf Alzahrani Dr. Saddiq Jastniah
King Abdulaziz University
Faculty of Applied Medical Science
Radiology Department-
2nd year

2. What is a computed tomography Scan
It is a non-invasive medical imaging procedure that combines the use of X-rays and computer processing to generate tomographic (‘slices’) of the area scanned.
A computerized axial tomography scan is more commonly known by its abbreviated name, CAT scan or CT scan
Four classifications of the types of scans: Abdominal-Bone-Head-Vascular

3. CT scanner

4. System components of CT scanner
scanner room
computer room
CT unit is divided into three main rooms:
System components of CT scanner CT unit is divided into three main rooms: the scanner room, operating room and computer room.
operating room

5. Scanner room
GANTRY.
PATIENT COUCH (table).
Automatic Injector

6. GANTRY
This is shaped like a giant donut and it maintains the alignment of the x‐ray tube and detectors

7. :Gantry Houses X‐ray tube Detector arrays (components) from inside :
X‐ray tube: produce the x‐rays (ionizing radiation) with continuous exposure.
Filter: to reduce the low energy x‐rays which are not useful for imaging
Collimators: • Pre‐patient collimator mounted on the tube housing, creates more parallel beam and reduce patient dose. • Post‐patient collimator reduces the scatter radiation on the detector.
Detector arrays: to absorb the x‐ray beam and located at the opposite side of the tube.
X‐ray tube
Detector arrays

8. Filter
pre C
Patient
post C
Detector
DAS

9. components from out side :
Control panel.
Display panel.
Aperture
Emergency button.

10. Control panel When pressed, the table moves in, toward the .Gantry
Description
Function
Icon
When pressed, stops X-ray exposure, turns off the laser alignment lights, halts all gantry and table motions.
Stop Scan
Scan Start
When pressed, the table moves in, toward the
.Gantry
Table In
When pressed, the cradle moves out, away from the
gantry.
Table Out
When pressed, the table moves up and towards the gantry. When the table moves up with the laser alignment lights on, the cradle will adjust horizontally to maintain the anatomic reference point
Table Up
Control panel

11. Control panel Description Function Icon
When pressed, the table moves down and away from the gantry.
Table Down
When pressed in conjunction with Table Up/Down or Cradle In/Out, causes those functions to operate at a faster speed.
Fast Speed
Pressing allows you to view the current gantry tilt range and scannable range, based on table position, on the gantry display panel.
Tilt and
Table
Travel
Limits
Control panel
A toggle when pressed, turns all the laser alignment lights on or off. These are used to help establish landmark locations.
Laser
Alignment
Light
Pressing (Cradle Lock) once unlocks the table, making it "free floating". This means that the cradle can be moved freely with your hands.
Table
Lock/Release
Pressing (Home) simultaneously moves the cradle out of the gantry and return the gantry tilt to zero degrees..
Home

12. The gantry display provides gantry and table status information

13. Table or Couch
The CT table may be either flat or curved and it is used to load a patient for scanning.
It is usually made of carbon fiber material that is strong enough;
the table must be capable of vertical (up‐down) and horizontal (in‐out) movements.

14. Automatic injector
Some examinations require injection of contrast media to highlight specific areas. The injector is used to inject the contrast through vessels automatically and it consists of: 1‐ Two syringes: one for contrast, and the other for saline "water". 2‐ Connecting tube. 3‐ Cannula (needle) with appropriate size. 4‐ Injector control monitor and it is located in the operating console room.

15. Accessories head holder Axial head holder Coronal head holder
U –shaped Foam insert
Cradle extender
Knee cushion
Arm support
Foam wedges

16. Operating Console Room
The operating console will usually have tow TV monitors:
1‐ Scan monitor: this monitor can be mainly used for scanning
patients, adjusting the technical factors, slice thickness, angle of gantry and initiates scan , record patient data(hospital identification, name , patient number, age ,sex ) and to provide identification for each scan.
2‐ Display monitor: used to view the resulting images to manipulate post scan data, post processing work‐measurement and 3D formations before sending to the radiologists.
3‐ Keyboard/mouse

17. Scan monitor
The Scan monitor contains the user interface that controls all aspects of scanning from entering patient information to ending the patient exam.

18. Keyboard and Scan Interface module2 1 7 3 6 4 7 5 .
Emergency Stop - In the event of an emergency situation, pressing emergency stops, stops all table and gantry motions.
Exposure Indicator - The (Exposure Indicator) illuminate amber when an actual exposure is taking place.
Start Scan - The (Start Scan) indicator flashes green once the tube has reached exposure speed. Simply press the button to start the scan. Start Scan will flash for 30
seconds before timing out.

19. cradle. Move to Scan will flash for 180 seconds before timing out.5
Move to Scan - The (Move to Scan) indicator flashes green indicating that the system is ready for you to advance the cradle into the starting position. Simply press the button to advance the
cradle. Move to Scan will flash for 180 seconds before timing out.
Remote Tilt (Prescribed Tilt)- Press (Prescribed Tilt) and hold the button down until the prescribe tilt is achieved.
Talk - Pressing (Talk) and speaking towards the intercom above the button allows you to communicate with the scan room.
Volume Control (operator to patient) - This dial controls the volume of the operator’s voice to the patient.

20. What we do when patient come ??

21. Set Up Patient Information
Use this procedure each time you start a new patient exam. It is best to setup the patient information before you get the patient on the table.
click Patient Schedule,
2. From the scan monitor, click [New Patient].
3. click {add patient}
The Patient Information screen appears automatically displaying the new Exam
Number. Enter the patient information.
Click [Accept] to save changes and add patient information to the schedule list.

22. 1. From the scan monitor, click [New Patient]. 2
1.From the scan monitor, click [New Patient]. 2. Then Set Patient Information

23. Position the Patient
1.Head first
2.Feet first

24. Selecting a Protocol
1. On the left monitor, place the mouse over the area that you want to scan and click on it.
􀂊 A list of all the protocols that you built in this area of the protocol manager appears.
2. From the list, select the protocol that you want to use by clicking on it.
Brain routine

26. Image
Scout View
Axial Image

28. What happens when x-ray passes through the patient?
Attenuated and measured by the detector
X ray tube and detectors are hidden inside the gantry of scanner and rotate around patient during scanning
Detector converts x ray photons into electrical signals (analog), which must be converted into digital (numerical) for input on computer
Computer makes the image reconstruction process
Reconstructing an image is in numerical form and must be converted into electrical signal so it can be displayed on a television monitor for viewing
Image can be stored on magnetic tapes or optical disks and recorded on x-ray film
The heart of the modern CT scanners is a computer, capable of reconstructing the image, If it wasn’t for computer technology the CT wouldn’t have been so useful to radiology

29. CT images

30. Manipulation
transverse axial images can be reformatted into coronal , sagittal , and three dimensional processing

31. Computer room
The computer is designed to solve many equations through controlling data acquisition, processing, displaying, and storage.

32. image storage
Scanners store image data on either floppy disk or magnetic tapes.
HARD COPY
LASER PRINTERS

33. COMMUNICATION
PACS
picture archiving and communication system (PACS)

34. Thanks for Your Attention