Equipment Operation and Maintenance. Grid-controlled tube Designed to turn on and off rapidly,...
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Transcript of Equipment Operation and Maintenance. Grid-controlled tube Designed to turn on and off rapidly,...
Equipment Operation and Maintenance
Grid-controlled tube
• Designed to turn on and off rapidly, providing short precise exposures
• Use in fluoro and in capacitor discharged (condenser-discharge) mobile units
• Uses a molybdenum focusing cup
FLUOROSCOPY
• INPUT PHOSPHOR– LARGE DIAMETER– CESIUM IODIDE– X-RAYS LIGHT
• PHOTOCATHODE– LIGHT ELECTRONS
• OUTPUT PHOSPOR– SMALLER DIAMETER– ELECTRONS LIGHT
FLUORO CONT.
• FOCUSSING LENSES• VIDICOM/PLUMBICON• BEAM SPLITTING DEVICE• mA• ABS• AGC or ABC
• FLUX GAIN=# OF OUTPUT LIGHT PHOTONS
# OF INPUT LIGHT PHOTONS• MINIFICATION GAIN = Diameter of input (squared) diameter of output (squared• BRIGHTNESS GAIN:
minification x flux
• Trifield Tubes• 25/17/12
smaller diameter of input phosphor reduces:field of viewmagnificationminification gain dimmer image
Larger film formatgreater the # of films =higher patient
exposure
• Cinefluoroscopy– rapidly obtained photospot image
(35mm film)15,30,60,90 frames per sec.
– cardiac cath
• Spot film– 12 frames per sec– smaller film size
• cassette loaded
FLUORO QUESTIONS
#9,24,30,36,38,40,44,47,5463, 69,70
AEC
• Collimation and AEC• Photodiode
– light sensitive– under table, behind cassette
• ion chamber– charge sensitive– above bucky and cassette– #10,14,25,27,34,81,92,102,113,
CIRCUITS
• Self induction = autotransformer and choke coil
• Mutual induction =High voltage transformer & filament circuit
• V = VS = NS
VP= NP
• I = NS = IP NP=IS
• Rectifiers• Filament circuit• rheostat• filament circuit
• Motor and generators• Rheostat• Star and wye configurations
– transformer windings in 3-phase circuits
– 5,20,23,26,35,45,46 ,51,52,53,74,77
THREE PHASE/SINGLE PHASE
HU • single phase=ma x time x kvp• three phase/ 6 pulse
ma x time x kvp x 1.35• three phase/12 pulse
ma x time x kvp x 1.41
VOLTAGE RIPPLE
• Single phase• three phase 6
pulse• three phase 12
pulse
• 100%• 13%• 4 or 3%• ?’s
35,64,96,97,99,105,106
Tomography
• Thinner the cut the _________the angle
• 43
QUALITY CONTROL TESTS
• SPINNING TOP TIMER• WIRE MESH SCREEN/FILM CONTACT
• PENETROMETER KVP AND CONTRAST
• STAR PATTERN FOCAL SPOT SIZE• CUTIE PIE ROENTGEN DOSIMETER
• WISCONSIN TEST TOOL KVP IN BEAM• GEIGER RADIOACTIVITY
spinning top tests
Spinning top testsSpinning top tests• half wave/single phase = exposure time x 60• Full wave/single phase = exposure time x 120 • Three phase –exposure time =arc size/360• timers and rectifiers• dots and dashes(12 dots of 1/10sec, 24 dots of
1/5 sec, 6 dots for 1/20 sec)• synchronous spinning top• solid arc• #18,28,41,50,57,61,66,65,68,
TUBE LIFE/HEAT LOAD
#6,12,16,33,44,73,77,101,
Mobile radiography, CT, Misc
• Capacitors- temporarily stores energy-no battery
• 2,3,4,22,37,42,55,58,71,78,87,88,120
DIGITAL
Corectec
Misc.
• Light absorbing dye in screens reduce diffusion of fluorescent light