Transcript EQUIPMENT OPERATION AND MAINTENANCE

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.
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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 viewmagnification
minification gain dimmer image
Larger film format
greater 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
#9,24,30,36,38,40,44,47,54
63, 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 = I P
NP=IS
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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
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Single phase
three phase 6 pulse
three phase 12
pulse
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100%
13%
4 or 3%
?’s
35,64,96,97,99,105,
106
Tomography
• Thinner the cut the _________the
angle
• 43
QUALITY CONTROL TESTS
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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
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Spinning 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 energyno 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