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