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Transcript of Week 1 Review Don’t forget: You can copy- paste this slide into other presentations, and move or...
Week 1 Review
Week 2: Radiographic Equipment
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Game PlanIdentify generic components of the radiographic equipment
Describe various planes of x-ray tube and table movement
Discuss contrast and density Exposure Factors
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Generic Components of Radiographic SystemX-ray Tube
Collimator Assembly
Radiographic Table
Control Console
Tube support
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Radiographic Room
X-ray Tube Housing
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X-RAY Tube Housing
• Lead and steel
• Absorbs stray radiation
• Prevents x-ray photons from leaking from tube
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X-RAY Tube
• Made with Pyrex glass– Withstands HIGH
heat loads
• Gas Evacuated– so electrons won’t
collide with the air molecules in the tube
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Early X-RAY Tube
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The X-RAY Tube
• Lead and steel housing
• Pyrex glass encased in a housing
• Primary components
ANODE (+)
&
CATHODE (-)
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X-RAY Tube
• Most important component
of the radiographic system
• Produces the X-rays
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X-Ray Machine
• Purpose:– provide a specific current (mA) & voltage
(kVp) to the x-ray tube• kVp controls the energy of the x-ray
photons• mA controls the number of x-ray photons
– convert electrical energy to electromagnetic energy (x- ray photons)
TO PRODUCE X-RAYS YOU NEED
A SOURCE OF ELECTRONS
A FORCE TO MOVE THEM QUICKLY
SOMETHING TO STOP THEM SUDDENLY
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Source of Electrons
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Cathode
• Filament– Thoriated
tungsten
• Focusing cup (beam focus)
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Process of x-ray production on Cathode side (-)
• mA (milliamperage) is sent to filament– Via cables
• Filament heats up – electrons “boil off” (thermionic
emission)– focusing cup focuses electron
beam toward anode
• Electrons have negative charge
A force to move them quickly.Something to stop them suddenly
22
Process of x-ray production on Anode side (+)
• Positive voltage (kVp) is applied
• Causes electrons to accelerate towards anode– Laws of attraction
• Electrons “slam into” target of anode – suddenly stopped.
• X-RAY PHOTONS ARE CREATED
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• High voltage to anode attracts electrons from cathode
• Current to stator causes rotation of anode
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Anodes - Target
Cu
W
•Common target (focal track)material is Tungsten
Molybdenum or Graphite base
Rotating Anodes• 2” to 5” disk (focal track)
Rotation speeds Low: 3,000 – 3,600 rpm High: 9,000 – 10,000 rpm
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X-ray Tube Anode
Stator and rotor make up the induction motor
Molybdenum stem connects rotor with anode reduces heat transfer to
rotor and bearings
Focal track area (spreads heat out over larger area than stationary anode configuration)
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Rotating Anode
Molybdenum stem and base usedbecause it is a poor heat conductor
Tungsten can withstand high heat loads
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How Are X-rays Made?
• Source of electrons
move at high speed (KE)
• Collide with target or focal track) on anode
• KE of electrons converted to x rays & heat
– 99% heat
– 1% x-ray photons
Collimator Knobs
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Collimator
• Attaches directly below the x-ray tube
• Serves as a beam limiting device
• Controls size and shape of the x-ray field
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Collimator Knobs
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Cone collimator
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Radiographic Table
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Tables• Tilting tables – diagnostic and
fluoroscopic work– 90 degrees in one
direction – 15 – 30 degrees in
the other direction– ancillary
equipment:• footboard,
shoulder support, handgrips, compression bands
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http://www.youtube.com/user/ARCOMAMED?blend=1&ob=5#p/a/u/2/C9fTjmQrfj8
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TABLE OR UPRIGHT BUCKY TRAY
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The ‘bucky’ is like a drawer
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Image Receptors and Bucky tray
Film
Image ReceptorsCassette Based
1) Film /screen (FS)
2) Computed Radiography (CR)
Cassette-less
1)Digital Radiography (DR)
Indirect CaptureDirect Capture
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Film Screen
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Darkroom for Film Screen Image receptors
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What is in the Darkroom?
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Safe Light
• 7-15 Watts
• Red filter
• Must be 3-6 feet from counter top or feed tray of processor
• Used to be amber or orange filter
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FILM SCREEN PROCESSOR
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CR- PSP plate
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CR Reader for Computed Radiography image receptors
Multiloader
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Digital Radiography: Direct Capture
Amorphous selenium
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Digital Radiography: Indirect Capture
Amorphous silicon
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• The bucky tray can be found:– In the table
or chest board
• Holds the cassettes– CR– Film
Screen
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60Bucky tray
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Bucky Tray
Image receptor is held in bucky
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FLUOROSCOPY: Images in motion
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REMOTE ROOM
Conventional Room
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FLUOROSCOPYmust wear shielding
while x-ray beam is on
Lead apron Lead Curtain
Tube SupportsDesigned to help technologists with various
tube locations for creative imaging.
Tube suspension systems are available in 5 versions
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Floor mounted & Overhead Suspension
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Floor to Wall or Ceiling
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Table Suspension
Telescoping Tube
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Tube Movement
• Longitudinal
• Transverse
• Vertical
• Angling or Rolling
• Rotating
• Telescoping
CONTROL CONSOLEGives the
technologist control of the xray machine
Technique selection
Located OUTSIDE of the Radiographic Room
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kVp & mAs
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The Control Console
• Set technical factors (mAs & kVp)
• Make an exposure
• Only a legally licensed individual is authorized to energize the console
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“Technique”kVp , mAs (mA x s)
• What is set at the control panel
• How the “image” is created on the “film” or Image receptor (digital)
• kVp controls the “ENERGY” of the beam
• The Higher kVp – more penetrating
• Ranges is 50 -110 in Diagnostic x-ray
77
“Technique”kVp , mAs (mA x s)
• mA- is the current in combination with the time – determines HOW LONG the beam will stay on
• Controls the density on the film/image
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Ancillary EquipmentGrids
View boxes and viewing computers
Darkroom
Processors and Readers
Misc Equipment
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Grids• Body parts
10cm & more
• Lead strips parallel to centerline
• Absorbs scatter– Improves
detail
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Scatter adds a “foggy appearance
Makes image more gray
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Other x-ray equipment
• Positioning phantoms • Pixie
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Other x-ray equipement• Positioning sponges• Lead markers
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Positioning sponges
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Lead Shields
Gonad shields
Lead wrap arounds
Lead aprons
Lead Gloves and Glasses
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Are x-ray machines prisoner to one room???
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Mobile X-RAY equipment
• Portables– Take machine to
patient
– Still images
• C-arm– Used in
interventional procedures
– Used in surgery
– Dynamic images
– Fluoroscopy
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PORTABLE UNITS
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Trauma wrist done portable- using positioning devices
Lead apron
sponge
TAPE
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When patients cannot go the Radiology Department
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Review
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X-ray Tube Construction
GF
ED
C
A
B
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X-ray Tube Construction
A. Glass housing (envelope)
B. Molybdenum neck of the anode
C. Stators /Electromagnets
D.Tungsten anode (focal spot)
E. Window or port for beam exit
F. Filament (cathode)
G. Focusing cup
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TUBE HOUSING
What is it made of?
106
Is this rotating or stationary anode?
What is required to produce x-rays?
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What is required to produce x-rays?
Requirements:
– a source of fast moving electrons
– sudden stop of the electrons’ motion (KE)
– kinetic energy (KE) is converted to EMS energies
• Heat
• x-ray photons