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

#1,13,19,30,38,39,47,54,69,75,89100, 114

AEC

• Collimation and AEC• Photodiode

– light sensitive– under table, behind cassette

• ion chamber– charge sensitive– above bucky and cassette– #10,16,27,34,81,92,102,113,116

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• parallel circuits• series circuits• Star and wye configurations

– transformer windings in 3-phase circuits– 20,23,26,31,37,45 ,51,52,53,74,78

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 35,64,88,

84,85,96,97

Tomography

• Thinner the cut the _________the angle

• 2, 40, 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• #5,28,29,50,57,61,70,

TUBE LIFE/HEAT LOAD

#6,7,44,,73,99,104,

Mobile radiography

• Capacitors- temporarily stores energy-no battery

• 4,42,62,87

DIGITAL

#3,9,16,56,67

Misc.

• Light absorbing dye in screens reduce diffusion of fluorescent light