Chapter 6 Flashcards
2 types of X-ray units
Diagnostic and Therapeutic
Diagnostic ranges
• 10-1200 milliamperes (mA)
• 0.001-10 seconds
• 25-150 kilovoltage peak (kVp)
Therapeutic radiation uses
Radiation oncology
• Uses electron therapy
Xray table is made from
Radiolucent top of carbon graphite fibers
Different tables for X-rays
Curved
• Flat
• Fixed
• Tilted
• Adjustable heights
• Footboard and shoulder supports
• Compression bands
Most common xray table
Flat surface
Xray table must
• Easy to clean
• Free of crevices that could collect contrast media
Difficult to scratch
Bucky tray
Different xray machines
Overhead suspension system (hospital standard)
• Floor to ceiling suspension
• Floor suspension system
• C-arm
Facts about a upright unit
Supports image receptor in a vertical orientation
• Bucky assembly
• May include AEC
• Vertical travel
• Tilting or non-tilting
6 other DIAGNOSTIC EQUIPMENT
Mammography
• Tomography
• Dental/ panoramic
• Computed tomography (CT)
• Radiation therapy simulators
• Urologic
Inefficient x-ray production generator
Single phase (half wave & full wave)
Most popular and widely
available generator
High frequency
Most efficient type of electrical power generator
High frequency
Least efficient generation to most
Single wave
Three phase
High frequency
2 circuits for X-ray
Main and filament
Circuit that Supplies x-ray tube with
properly modified power to
properly modified power
create an appropriate
to produce x-rays.
Main circuit
What circuit Supplies filament with properly modified power to create an appropriate thermionically emitted electron cloud.
Filament circuit
What circuit Low voltage side of circuit
Filament
What circuit Provides current and voltage to filament
Filament
What circuit Permits selection of milli-amperage (mA)
Filament
What circuit High voltage side of circuit
Main circuit
Which circuit has Exposure switch
Main circuit
Which circuit has Timer circuit
Main circuit
Remote control device that permits current to flow through the circuit.
Exposure switch
Activates the rotating anode of the x-ray tube.
Exposure switch
Must be attached to console so operator cannot be exposed
Exposure switch
1 or 2-step switch
Exposure switch
ALL switches are “dead man” type meaning
x-ray exposure only occurs while the switch is depressed (must have pressure)
Regulates exposure termination
Timer circuit
Most sophisticated timer circuit
Electronic timer
Timer circuits Capable of very short exposure times. How short?
0.001 second
• Terminates exposure based upon a predetermined mAs value
Milliampere-second (mAs) timers
Types of timer circuits
AEC TIMER
mAs Timer
Electronic timer
What timer circuit has Special ionization chambers
AEC
AEC Preset to terminate exposure when
enough x-ray energy is received
AEC has how many chambers
Three chamber position
AEC stands for
Also called Automatic Exposure Device.
“Phototiming” is an antiquated term for
AEC
AEC are located
Located in front of image receptor (IR)
AEC has how thick of parallel plate
5-mm parallel-plate chamber
With the AEC what is critical
Positioning
Collimation
Proper chambers activated
Multiple AEC chambers activation results in “”.
averaging
AEC is m made to be used for
large part radiography.
With AEC Collimation must not “cut off” part of an.
activated ionization chamber
Exposure Charts are still necessary to specify
technical parameters to be used.
Response Reaction Time is the
Minimum amount of time required to terminate exposure in AEC
Modern minimum reaction time:
• 0.001 seconds
BACKUP TIME CIRCUIT
• Used to
protect patient and equipment
Equipment often allows technologist to set backup
• Should be set at
150 percent of anticipated manual technique
Maximum exposure per U.S. Public Law:
• 600 mAs
• Exposures >50 kVp
