M Part I Flashcards
Three Principles of X-ray Imaging System
- X-ray Tube
- Operating Console
- High Voltage Generator
It is attached to an overhead
Movable assembly
Location: examination room
Radiographic X-ray Tube
Localized under examination table
Fluoroscopic X-ray Tube
It must be transparent to x-rays as much as possible
Examination Table
Composition of examination table
Strong and absorbs a little bit of radiation
Carbon fiber
Fluoroscopic table degree of tilt
[..] to the foot side
[..] to the head side
90 degrees
30 degrees
It is housed in an equipment cabinet positioned against the wall
It is always close to the x-ray tube
High voltage generator
Material familiar to the radiographic table
Used to control the X-ray tube current and voltage applied to x-ray tube
Provides control of line compensation
KVp, mA, exposure time
Operating Console
Number of x-ray
Intensity of the x-ray beams
Units: mR/mAs
Radiation quantity
Penetrability of the x-ray beam
Expressed in kilovolt peak (kvp)
Radiation quality
Inside operating console
Measures the voltage provided to the x-ray imaging system
Ph - 120 V
US - 110 V
Line Compensator
Consists of only one winding of wire
Autotransformer
[function, location] Autotransformer
Supplies the precise voltage circuit controls the kVp
Inside operating console
Autotransformer require [..] to approximately increase twice the input voltage value
Step up voltage
It conducts the input power to the autotransformer
Primary connection
State the AUTOTRANSFORMER LAW/ formula
It states that the voltage receive & provide by the transformer is directly proportional to the no of turns
Vs/Vp = Ns/Np
Adjustment of Kilovoltage Peak (kVp) [adjustment controls]
represent two separate series of connections on the autotransformer.
Major and minor kVp
It determines the quality of the x-ray beam
-kVp
[part, location] It reads voltage (not kVp)
-kVp meter
-location: output terminals of the autotransformer
It allows the voltage to be monitored before an exposure
Prereading kVp Meter
It is measured in milliamperes (mA)
X-ray tube current
It determines the number of electrons emitted by the filament
Filament Temperature
It controls the filament temperature
It is measured in amperes (A)
Filament Current
Filament Current [Range]
3-6 A
It controls x-ray tube current
Filament Circuit
Explain SPACE CHARGE EFFECT
A phenomenon of the space charge that makes it difficult for subsequent electrons to be emitted by the filament because of electrostatic repulsion
Electron cloud near the filament
Space Charge
The release of electrons from a heated filament
Thermionic Emission
It is used to reduce the voltage to a value that corresponds to the selected milliampere
Precision Resistor
Design in which exposure factors are adjusted automatically to the highest mA at the shortest exposure time allowed by the high-voltage generator
Exposure behind at maximum mA and it drops as the anode heats
Falling Load Generator
Result of falling load generator
Minimum exposure time
The product of X-ray tube current (mA) and exposure time (s)
A measure of electrostatic charge
-mAs
It monitors the X-ray tube current
-mA Meter
[location, rationale] mA Meter
It is connected at the center of the secondary winding of the high voltage step up transformer
rationale: ensures electrical safety
Filament Transformer [full name]
Filament Heating Isolation Step-down Transformer
Received the voltage from the mA selector switch
Provides the current to heat the filament
Filament Transformer
Filament transformer step down the voltage to approximately [..]
12 V
Primary Windings
[material]
Current: [..]
Voltage: [..]
Thin copper
0.5-1 A
150 V
Secondary Windings
[material]
Current: [..]
Voltage: [..]
Thick
5-8 A
12 V
It terminates an exposure after a prescribed time (6s)
Guard Timer
It consists of an electronic device
-make and breaks the high voltage across the x-ray tube
-always done on the primary side
Time Circuit