Slide 1

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

Slide 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

Slide 3

CT scanner

Slide 4

System components of CT scanner scanner room operating room computer room CT unit is divided into three main rooms:

Slide 5

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

Slide 6

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

Slide 7

: Gantry Houses ( 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

Slide 8

Filter preC Patient postC Detector DAS

Slide 9

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

Slide 10

DescriptionFunctionIcon 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

Slide 11

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 DescriptionFunctionIcon 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 Pressing (Home) simultaneously moves the cradle out of the gantry and return the gantry tilt to zero degrees.. Home Control panel

Slide 12

Gantry Display The gantry display provides gantry and table status information

Slide 13

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.

Slide 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.

Slide 15

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

Slide 16

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 workmeasurement and 3D formations before sending to the radiologists. 3 Keyboard/mouse

Slide 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.

Slide 18

1. Emergency Stop - In the event of an emergency situation, pressing emergency stops, stops all table and gantry motions. 2. Exposure Indicator - The (Exposure Indicator) illuminate amber when an actual exposure is taking place. 3. 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. 1. Emergency Stop - In the event of an emergency situation, pressing emergency stops, stops all table and gantry motions. 2. Exposure Indicator - The (Exposure Indicator) illuminate amber when an actual exposure is taking place. 3. 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.. Keyboard and Scan Interface module 2 13 475 7 6

Slide 19

5 4. 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)- 5. Remote Tilt (Prescribed Tilt)- Press (Prescribed Tilt) and hold the button down until the prescribe tilt is achieved. Talk - 6. Talk - Pressing (Talk) and speaking towards the intercom above the button allows you to communicate with the scan room. Volume Control (operator to patient) 7. Volume Control (operator to patient) - This dial controls the volume of the operators voice to the patient.

Slide 20

Slide 21

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. 1.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. Set Up Patient Information

Slide 22

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

Slide 23

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

Slide 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

Slide 25

Slide 26

Image 26 Scout View Axial Image

Slide 27

Slide 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

Slide 29

CT images

Slide 30

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

Slide 31

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

Slide 32

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

Slide 33

COMMUNICATION PACS

Slide 34