1
Q
2 separate rooms for CT:
A
- Scanner Room
- Controller Room
2
Q
MAIN COMPONENTS OF CT:
A
- THE GANTRY
- THE PATIENT COUCH OR PATIENT’S TABLE
- THE DATA ACQUISITION SYSTEM
- OPERATING / CONTROL CONSOLE
3
Q
The donut like or ring shaped part of the CT scanner.
A
GANTRY
4
Q
It houses many of the components necessary to produce and detect X-rays.
A
GANTRY
5
Q
Since transmission profiles have to be recorded under different angles, these components are mounted
on a?
A
rotating scan frame
6
Q
have to be recorded under different angles
A
transmission profiles
7
Q
The largest component the CT installation.
A
GANTRY
8
Q
Allow the patients to be positioned within the X-ray field by the table assembly.
A
circular aperture
9
Q
The range size of aperture:
A
70 to 90 cm
10
Q
Gantry may be tilted to an angle of?
A
30degs
10
Q
Control panels allow the technologist to control the:
A
- alignment lights
- gantry tilt
- movement of the table
11
Q
Features of the Display panel:
A
Displays the:
- gantry tilt
- table height,
- position of the landmarks
- scannable and tilt range
12
Q
Most scanners, may also be controlled via the?
A
operator’s console
13
Q
Installed in the gantry to allow communication between the patient and the technologist throughout the scanning procedure.
A
Microphone
14
Q
Used to position the patient within the scanner.
A
Laser Light
15
Q
Etra External components of the gantry:
A
- Control panels
- Display panel
- Emergency stop button
- microphone
16
Q
CT Gantry Internal Components:
A
1.X-ray tube, filters & collimators
2.Detector assembly
3.Tube controller
4.High freq. generator
5.Onboard computer
6.Stationary computer
17
Q
CT scan tube must be designed to handle a very large amount of?
A
Stress
18
Q
_ produce the X-ray photons that create the CT image.
A
X-ray tubes
19
Q
X-ray tubes produce the _ that create the CT image.
A
x-ray photons
20
Q
X-ray tubes produce the X-ray photons that create the _.
A
CT image
20
Q
X-ray tube design is a modification of?
A
standard rotating anode tube
20
Q
Often used for the anode target material because it produces a higher intensity.
A
Tungsten
20
Q
Tungsten atomic number
A
74
21
Anode heating capacity of an x-ray tube:
500k HU(5MHU)
22
used to shape the X-ray beam
Compensating filters
22
Power requirements:
120kV at 200-500mA
22
anode cooling rates:
1MHU/min and can be energized up to 60s
23
Compensating filters are used to?
shape the X-ray beam
24
Reduce the radiation dose to the patient and help to minimize image artifact.
Compensating filters
25
Compensating filters reduce the _ to the patient and help to minimize _.
reduce radiation dose; minimize image artifact
26
Radiation emitted by CT scan X-ray tube is _.
Polychromatic
27
Filtering the X-ray beam helps to reduce the range of X ray energies that reach the patient by removing the?
long wavelength or soft X-rays
28
Are readily absorbed by the patient, therefore they do not contribute to the CT image but do contribute to the radiation dose to the patient.
long-wavelength X-rays
29
Improves the CT image by reducing
artifacts that result from beam hardening.
uniform beam intensity
30
In addition, creating a more uniform beam intensity improves the CT image by reducing artifacts that result from _.
Beam hardening
31
Restrict the X-ray beam to a specific area, as a result it helps reduce scatter radiation.
Collimation
32
Reduces image quality and increase the radiation dose to the patient.
Scatter radiation
33
What happen if you decrease scatter radiation:
- improves contrast resolution
- reduce patient dose
34
Control the slice thickness by narrowing or widening
the X-ray beam.
Collimator
35
The source collimator is located where?
Near the X-ray source
35
In MDCT systems, slice thickness is also influenced by the?
detector element configuration
35
Pre-patient collimators are made out of?
thick metal plates
36
Pre-patient collimators are located where?
outside the x-ray tube
36
Scanner vary in the choices of slice thickness available. Choices range from:
0.5 to 10 mm
37
Define beam width and restrict the shape of the x-ray beam before it ever reaches the patient.
Pre-patient collimators
38
In single-slice CT scanning, pre-patient collimators define the _ of the cross sectional slice.
thickness
39
In single-slice CT scanning, what define the thickness of the cross sectional slice?
Pre-patient collimators
40
What defines the thickness of the x-ray beam in multi-slice CT scanning?
Pre-patient collimators
41
Post-patient collimator are positioned where?
above the detector array
42
In multidetector CT scanning, what determines the slice thickness?
image reconstruction
43
Post-patient collimation also works in conjunction with pre-patient collimation to?
Help define slice-thickness
43
Results in lower resolution, but it provides better volume coverage speed.
Wider collimation
43
Results in better resolution, but it takes longer to scan a particular area of anatomy.
Thin collimation
43
If post-patient collimation is reduced, the slice thickness _.
decreases
44
A component of CT scan machine which collect information regarding the degree to which each anatomic structure attenuated the beam.
detector
45
Refers to a single element or a single type of detector used in a CT system.
Detector
46
This term is used to describe the entire collection of detectors included in a CT scan system.
Detector array
47
The detector array comprises detector elements situated in an?
arc/ring
47
Help to calibrate data and reduce artifacts.
reference detectors
48
Optimal Characteristics of a Detector:
- High detector efficiency
- Low or no Afterglow
- High Scatter Suppression
- High Stability
48
Is a brief, persistent flash of scintillation that must be taken into account and subtracted before image reconstruction.
Low or no Afterglow
48
It is the ability of detector to capture transmitted photons and change them to electronic signals.
High detector efficiency
48
Allow a system to be used without the interruption of frequent calibration.
High Stability
49
TYPES OF DETECTORS:
- Xenon Gas Detectors
- Solid State Crystal Detector
50
Xenon Gas Detectors absorbs how many percent of photons that reach them?
60% to 87%
50
Xenon gas is used because of its ability to remain _ under pressure.
stable
50
Main disadvantage of xenon gas:
It must be kept under pressure in a certain extent
51
A xenon detector channel consists of how many tungsten plates?
3 tungsten plates
52
Disadvantages of xenon gas:
- It must be kept under pressure in a certain extent
- Loss of X-ray photons in the casing window
- Space taken up by the plates
53
Types of scintillation crystals:
- Sodium Iodide (NaI)
- Bismuth Germanate(BGO) and then Cesium Iodide(CsI)
- Cadmium tungstate(CdWO4) + Si Photodiode
53
Sodium Iodide (NaI) was used by what generation CT?
Earliest generation
53
Sodium Iodide (NaI) was replaced by?
Bismuth Germanate(BGO) and Cesium Iodide(CsI)
53
Bismuth Germanate(BGO) and then Cesium Iodide(CsI) are replaced by?
Cadmium tungstate(CdWO4) + Si Photodiode
54
Cadmium tungstate(CdWO4) + Si Photodiode are used by what generation of CT?
3rd and 4th gen
55
Solid state detectors are also called?
scintillation detectors
56
Attached to the crystal and transforms the light energy into electrical (analog) energy.
photodiode
57
The individual detector elements are affixed to a?
Circuit Board
58
Solid state crystal detectors material (ceramic rare earth compounds):
- gadolinium
- yttrium
59
Solid state detectors have higher _ than gases.
higher absorption coefficients
60
A material property indicating how effectively a substance absorbs electromagnetic radiation (like light) or sound waves of a specific wavelength or frequency.
absorption coefficient
61
Solid state crystal detectors absorb how many percent of the photons that reach them?
100%
62
The electronic system that manages the power supply to the X-ray tube in a CT scanner.
Tube Controller
63
Functions of a tube controller:
- Regulates Tube Voltage (kVp)
- Controls Tube Current (mA)
- Timing and Exposure Control
- Monitors Tube Load & Heat
- Supports Modulation Techniques
64
Ensures the selected kVp remains constant to produce consistent X-ray photon energy.
Regulates Tube Voltage (kVp)
65
Important for image contrast and penetration.
Regulates Tube Voltage (kVp)
66
Adjusts the number of electrons hitting the anode per second, affecting the quantity of X-rays produced.
Controls Tube Current (mA)
67
Can work with automatic exposure control (AEC) to optimize patient dose.
Controls Tube Current (mA)
68
Determines when the tube is energized (exposure on/off) during data acquisition.
Timing and Exposure Control
69
Synchronizes with the gantry rotation and detector readout.
Timing and Exposure Control
70
Prevents overheating by tracking tube heat units.
Monitors Tube Load & Heat
71
Manages cooling intervals if limits are reached.
Monitors Tube Load & Heat
72
Enables tube current modulation (TCM) to reduce radiation dose by adjusting mA based on patient anatomy.
Supports Modulation Techniques
73
Generator that is currently used in CT scanners.
High frequency generator
74
Produce high voltage and transmit it to the X-ray tube.
High frequency generator
75
The power capacity of the generator is listed in?
kilowatts (kW).
76
This determines the range of exposure techniques like kV and mA settings, available on a particular system.
power capacity of the generator
77
CT generator produce high kV generally:
120 – 140 kV
78
Help to reduce the heat load on the X-ray tube.
higher kV setting
79
Helps extend the life of the tube.
Reducing heat load
80
In addition, a higher kV setting will help to reduce the heat load on the X-ray tube by allowing a?
lower mA
81
Technical setting to help reduce heat load of the x-ray tube.
High kVp; lo mA
82
Another form of HVG
Transformer
83
Provides the CT units the necessary power to operate.
Transformer
84
What type of transformer is being used in CT scans?
Step-up type transformer
85
A transformer does not change the?
power levels
86
Regulates the Kv and mA and provides the mechanism for information i/o across the slip ring.
ONBOARD COMPUTER
87
Provides the mechanism for the i/o exchange to and from the operator console.
STATIONARY COMPUTER –
88
Important because many components can be affected by temperature fluctuations.
Cooling System
89
Other gantry features:
- Rotational speed
- Multi-slice helical CT
- Interpolation to transverse -
- Slices-
90
Rotational speed of gantry:
3600-10800rpm
91
Refers to a special CT system equipped with a multiple-row detector array to simultaneously collect data at different slice locations.
multi-slice CT scanner
92
A mathematical process used to smooth, enlarge or average images that are being displayed with more pixels than that for which they were originally reconstructed.
Interpolation
93
Depending on the scanner, patient couch can hold up to?
227kg
94
Refers to the number of rows of detectors in the z-axis of a CT.
Slice
95
This is designed to prevent too large patients to be forced into the scanner.
Weight range/ 227kg
96
The patient couch or patient's table material should be of?
low atomic number
97
THE DATA ACQUISITION SYSTEM:
- X-RAY TUBE DETECTORS
- COLLIMATORS
- FILTERS
98
The DAS is housed inside the?
GANTRY
99
Refers to a method by which the patient is systematically scanned by the X-ray tube and detectors to collect enough information for image reconstruction.
Data Acquisition
100
This is when the raw signals from detectors are converted into digital data which are then processed by special algorithms (mathematical formulas) and the computer reconstructs it into cross-sectional images (slices).
Central Processing
101
The scanning process begins with?
data acquisition
102
The master control center of the CT Scanner.
OPERATING / CONTROL CONSOLE
103
Optional components of CT scans:
- Power Injector
- CCTV
- Dehumidifier
- UVC Lamp
103
OPERATING / CONTROL CONSOLE FUNCTIONS:
* Controls data acquisition
* Image reconstruction/reformation
* Storage of image data
* Image display
103
It is used to input all of the technical factors and data related to taking a scan.
OPERATING / CONTROL CONSOLE
104
Remove excess moisture from the air to protect sensitive electronic components, prevent condensation on the X-ray tube and detectors, and ensure accurate image quality by reducing the risk of artifacts.
dehumidifiers
105
Helps sanitize the air and surfaces, reducing the risk of cross-infection
UVC Lamp
COMPUTED TOMOGRAPHY
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