Sir syed university of engineering & technology Karachi

1. BIOMEDICAL ENGINEERING SYSTEM
Title:
COMPONENTS OF CT SCANNER
ENGR KHALEEQUE AHMED
SIR SYED UNIVERSITY OF ENGINEERING &
TECHNOLOGY KARACHI

2. CT Gantry External View
1.gantry aperture (720mm
diameter)
2.microphone
3.sagittal laser alignment light
4.patient guide lights
5.x-ray exposure indicator light
6.emergency stop buttons
7.gantry control panels
8.external laser alignment lights
9.Patient couch
10.ECG gating monitor

3. CT Gantry internal View
1. x-ray tube
2. filters, collimator, and reference
detector
3. internal projector
4. x-ray tube heat exchanger
5. high voltage generator (0-75kV)
6. direct drive gantry motor
7. rotation control unit
8. data acquisition system (DAS)
9. Detectors
10.slip rings
11.detector temperature controller
12.high voltage generator (75-
150kV)
13.power unit (AC to DC)
14.line noise filter

4. GANTRY
 The Gantry includes the
 The X-ray tube
 The Detector Array
 The High-Voltage generator
 The patient Support Couch

5. THE X-RAY TUBE
 CT x-ray tubes are very large.
 They have an anode heat storage capacity
of 8 MHU (million heat unit) or more.
 They have anode-cooling rates of approx
1MHU per minute because the anode disc
has a larger diameter, and it is thicker.

6. THE DETECTOR ARRAY
 CT imaging system have multiple detectors in an
array that numbers up to tens of thousands.
 Previously gas-filled detectors were used, but now,
all are scintillation, solid state detectors.
 Early scintillation detector arrays contained
scintillation crystal-photodiode assemblies
because photodiodes convert the light into an
electronic signal..

7. CONTINUED
 The combination of a scintillation crystals
and the light detector is called a
scintillation detectors.
 The concentration of detectors is an
important characteristic of a CT imaging
system that affects the spatial resolution of
the system.

8. COLLIMATION
This collimator reduces scatter radiation that
reaches the detector array, thereby improving
the image contrast and also determines the
slice thickness.
 In CT imaging, two collimators are used.
 One collimator is mounted on the x-ray tube
housing or adjacent to it.

9. CONTINUED
 This is called Prepatient collimator that
determines patient dose.
 Second collimator is called predetector
collimator.

10. THE HIGH VOLTAGE GENERATOR
 All CT imaging system operate on high
frequency power.
 A high-frequency generator is small
because the high-voltage step-up
transformer is small, so it can be mounted
on the rotating gantry.
 Tube potential (80-140 KV).
 Tube current (20-500 mA).

11. THE PATIENT SUPPORT COUCH
 To support the patient comfortably, the patient
couch must be constructed of low Z-material,
such as carbon fiber.
 It does not interface with x-ray beam
transmission and patient imaging.
 When the patient couch positioning is not exact,
the same tissue can be imaged twice , thus
doubling the dose, or it can be missed altogether.

12. PATIENT TABLE
 The table is a flat or slightly curved platform
that the patient lies on during the scan.
 The table is responsible for positioning the
patient with the gantry.
 Up/down positioning movements are
available as well as the longitudinal
positioning of the patient into the gantry
aperture.

13. POWER DISTRIBUTION UNIT
 The power distribution unit is the power
supply for the x–ray tube, scanning
movement drive motors, table, and the
detectors.

14. OPERATOR CONSOLE
 CT imaging systems can be equipped with
two or three consoles.
 One consoles is used by the CT radiologic
technologist to operate the imagine system.
 Another console may be available for a
technologist to post-process images for
filming and filing.
 A third console may be available for the physician to
view the images and manipulate image contrast,size,
and general visual appearance.

15. Operating Console
Workstation